what is glass transition temperature?

August 21st, 2024

In the PCB manufacturing process, the glass transition temperature is an important performance indicator. During the manufacturing and use of PCB boards, they will undergo multiple heating and cooling processes. If the operating temperature exceeds the glass transition temperature, the board will soften, expand, or even deform, affecting the accuracy and reliability of the circuit. Therefore, choosing the right glass transition temperature is crucial to ensure the dimensional stability and long-term performance of the PCB.

What is the glass transition temperature and Its Significance?

The glass transition temperature (Tg) refers to the temperature corresponding to the transition from the glass state to the high elastic state. The glass transition is an inherent property of amorphous polymer materials and a macroscopic manifestation of the transformation of the polymer motion form. It directly affects the performance and process performance of the material. Therefore, it has long been the main content of polymer physics research.

The glass transition temperature is of great significance to the application of polymers. Above this temperature, polymers show elasticity; below this temperature, polymers show brittleness. This characteristic must be considered when used as plastics, rubber, synthetic fibers, etc.

The glass transition temperature of mainstream FR-4 boards is approximately between 130-140℃. In the PCB manufacturing process, the temperature needs to be strictly controlled to avoid exceeding the glass transition temperature to ensure the quality of the product.

Is higher glass transition temperature better?

In PCB manufacturing, the higher the glass transition temperature (Tg), the better. ‌

The glass transition temperature is an important performance indicator of polymer materials, which determines the changes in the physical and chemical properties of the material at a specific temperature. When the temperature of the polymer is lower than its glass transition temperature, the material exhibits hard and brittle characteristics, similar to the glass state; when the temperature is higher than the glass transition temperature, the material becomes soft and exhibits elasticity similar to rubber or leather. This state change has a direct impact on the performance during PCB manufacturing and use.

1. ‌ Temperature deformation resistance ‌:

The higher the Tg value, the stronger the material’s temperature deformation resistance. This means that in a high temperature environment, such as during SMT welding, the PCB substrate is not easy to deform, thereby maintaining dimensional stability, which is crucial to ensure the reliability and long-term use of the circuit board.

2. ‌ Electrical performance and mechanical strength: ‌

The high or low Tg value directly affects the electrical performance and mechanical strength of the PCB. High Tg materials can maintain good physical and chemical stability at high temperatures, thereby maintaining the electrical properties and mechanical strength of the circuit board, which is crucial to improving the quality and reliability of the product.

3. Safety:

PCB materials with high Tg values are not easy to soften or melt at high temperatures, thereby improving the safety and durability of the circuit board and reducing the risk of short circuits or other damage caused by high temperatures.

In summary, choosing PCB materials with higher Tg values is one of the key factors to ensure that the circuit board maintains stable performance and safety in complex manufacturing and use environments.

What is glass transition temperature vs melting temperature?

In PCB manufacturing, glass transition temperature and melting temperature are two different physical properties that describe the state changes of materials under different conditions. ‌

The glass transition temperature (Tg) mainly involves amorphous materials or amorphous regions in partially crystalline materials. At this temperature, the physical state of the material changes from glass to highly elastic.

The melting temperature (melting point) mainly involves the melting process of crystalline materials. For crystalline polymers, the melting point marks the temperature at which the molecular chain begins to move, that is, the material changes from solid to liquid. The melting point is related to the crystallinity and lattice structure of the material and is a physical property unique to crystalline materials.

In short, the glass transition temperature mainly affects the amorphous region in amorphous or partially crystalline materials, while the melting temperature mainly affects crystalline materials and involves the melting process of the entire crystal. These two temperatures reflect the different physical state changes of different materials when heated.

How do you determine the glass transition temperature?

Expansion method, thermomechanical method, differential scanning calorimetry (DSC), DTA method, dynamic mechanical property analysis (DMA) method, nuclear magnetic resonance method (NMR).

Differential scanning calorimetry (DSC) is the most traditional and commonly used measurement method. It measures the relationship between the power difference (heat flow rate) and temperature between the sample and the reference material, and then obtains the glass transition temperature of the material;

Dynamic mechanical analysis (DMA) is the most sensitive method. It measures the sinusoidal alternating stress of constant amplitude applied to the sample, observes the change of strain with temperature or time, and calculates the mechanical parameters to characterize the elastomer;

Thermomechanical analysis (TMA): Use a probe with good sensitivity to measure the expansion coefficient of the material, and measure the glass transition temperature of the material based on this change.

What is the difference between TM and Tg?

In the PCB industry, TM and Tg are two different parameters, representing two different physical properties.

Tm: melting point; m is the melting point of crystalline polymers, that is, the temperature at which crystalline polymers melt. It is the highest use temperature of crystalline polymers when used in plastics and fibers, and it is also their heat resistance temperature and the lowest temperature for molding processing.

What is the Tg of polyurethane?

The glass transition temperature (Tg) of polyurethane is not a fixed value, but a physical quantity determined by the type of resin.

‌There are many types of polyurethane, including polyether, polyester, polyimide, polyurea, etc. Each type of polyurethane has its own specific glass transition temperature.

Shape memory polyurethane has a small volume expansion rate at temperatures below Tg, but increases at temperatures above Tg, which shows the characteristics of its glass transition temperature. Therefore, to determine the glass transition temperature of a specific polyurethane, its specific chemical structure and application field need to be considered.

What is Tg for epoxy?

The Tg value of PCB epoxy resin is usually between 130℃ and 170℃. ‌

The Tg value (glass transition temperature) of PCB (printed circuit board) epoxy resin is an important performance indicator, which reflects the change in the physical state of the material when heated. According to different application requirements, the Tg value of PCB epoxy resin can be divided into several grades:

‌TG130‌: The temperature resistance of this type of board is about 140℃. Common Tg value boards of this type are Shengyi S1141 and Jiantao KB-6164F.

TG150: A medium Tg board with a temperature range of 150°C to 170°C. Common boards with this type of Tg include Shengyi S1141 150 and Jiantao KB-6165F.

TG170: A high Tg board with a temperature range of over 170°C. Common boards with this type of Tg include Shengyi S1170 and Jiantao KB-6167F.

Selecting the right Tg value is critical to ensuring the performance and reliability of the PCB. Although boards with high Tg values are relatively expensive, their superior temperature resistance is indispensable in applications that require higher temperatures, such as aerospace. In addition to Tg values, other factors should be considered when selecting PCB boards, such as thermal decomposition temperature (Td), which is another important indicator for evaluating the stability of boards at high temperatures.

Conclusion:

High Tg represents high heat resistance. Electronic products represented by computers are developing towards high functionality and high multi-layer, which requires higher heat resistance of PCB substrate materials as an important guarantee. BEST Technology focuses on manufacturing high-performance PCB circuit boards and is far ahead in the industry. It has professional production equipment and 18 years of design experience, and has high quality requirements for products.

Tags: fr4, glass, pcb design, SMT
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Let you know about PCB copper layer thickness

August 16th, 2024

In the printed circuit board industry, the most common way to express the copper layer thickness on a PCB is in ounces (oz). 1oz means 1oz of copper evenly covers an area of 1 square foot, which is about 1.4mil. It uses the weight of the tissue area to express the average thickness of the copper foil. Expressed in terms of formula, 1oz=28.35g/FT2 (FT2 is square feet, 1 square foot = 0.09290304 square meters).

What is the standard thickness of a copper layer on a PCB?

In the manufacture of printed circuit boards (PCBs), the thickness of the copper layer is an important parameter that directly affects the electrical performance and reliability of the circuit board. Depending on the application requirements, the thickness of the copper layer can vary within a certain range. Generally speaking, the conventional copper layer thickness is between 1-35μm, with 35μm being the most commonly used thickness. For some applications with high reliability requirements, the copper layer thickness may reach more than 50μm.

The selection of the thickness of the copper layer is a decision-making process that takes into account a variety of factors, including the conductivity, heat dissipation, mechanical strength, cost and manufacturing difficulty of the circuit board. A larger copper thickness can reduce resistance and improve the conductivity and heat dissipation of the circuit board, but it will also increase material costs and production difficulties. Therefore, when designing PCB boards, engineers need to select a suitable copper thickness standard range based on specific application scenarios and design requirements to ensure the performance and reliability of the circuit board.

1oz copper thickness in mm = 0.035mm

0.5 oz copper thickness in mm = 0.0175mm

1.5 oz copper thickness in mils = 0.0525mm

2 oz copper thickness in mils = 0.07mm‌

How thick is PCB copper after plating?

PCB printed circuit boards are usually bonded to glass epoxy substrates with a layer of copper foil, usually 18, 35, 55 and 70 microns thick. The most commonly used copper foil is 35 microns thick.

The copper foil used by PCB manufacturers is generally 35~50 microns thick, and some are thinner than this, such as 10 microns, 18 microns, and thicker such as 70 microns. The thickness of the composite copper foil on a 1~3 mm thick substrate is about 35 microns. The thickness of the composite copper foil on a substrate with a thickness of less than 1MM is about 18 microns, and the thickness of the composite copper foil on a substrate with a thickness of more than 5 mm is about 55 microns.

The copper layer thickness of PCB (printed circuit board) can be adjusted according to different needs and designs. Common copper layer thicknesses include 1oz (35μm), 2oz (70μm), 3oz (105μm), and other thicker options. For most applications, a copper layer thickness of 1oz is sufficient and suitable for general signal transmission. ‌For circuit boards that need to carry large currents, such as switching power supplies, a copper layer thickness of 2oz or higher is usually used. ‌In addition, there are some special cases where manufacturers provide extremely heavy copper up to 20 oz/ft2 (26.8 mils or 0.34 mm) to meet special needs. ‌

When choosing the thickness of the copper layer, factors such as the purpose of the circuit board and the magnitude of the signal voltage and current need to be considered. ‌For example, for circuit boards that require excessive current, a copper thickness of 70μm or 105μm may be used. ‌For thin laminates that require ultra-high density patterns, a copper thickness of 12μm may be used. ‌Therefore, the specific thickness of the PCB after copper plating is determined according to design requirements and specific applications.‌

How thick is 2 oz copper for PCB?

If 1 ounce (28.35 grams) of copper were flattened to evenly cover a surface area of 1 square foot (0.093 square meters), the resulting thickness would be 1.37mils (0.0348mm). A conversion chart for different units of measurement can be found below.

What is the difference between different copper thicknesses in PCB?

‌Copper is an excellent conductive material, and the thickness of the copper layer directly affects the conductive effect of the circuit board. ‌Thicker copper layers can provide lower resistance, reduce signal transmission losses, and are particularly suitable for high-frequency and high-speed digital circuits. ‌

During the operation of electronic equipment, good heat dissipation is a key factor in ensuring the performance and life of components. ‌Thicker copper layers can conduct and dissipate heat more effectively, preventing components from overheating. ‌

In high-power electronic devices, thicker copper layers can carry larger currents, avoiding burnout or performance degradation caused by excessive current.

Below is the conductivity corresponding to different copper thicknesses.

How thick is high current PCB copper?

In PCB design, copper thickness (also called copper thickness) is an important parameter, which directly affects the performance indicators of the circuit board such as current carrying capacity, heat dissipation and reliability. For PCBs that need to withstand high currents, such as high-power LED light strips, power circuit boards, high-power motor control boards or high-power inverter control boards, thicker copper layers are usually used to increase current carrying capacity.

Different uses have different copper foil thicknesses. Common 0.5oz, 1oz, and 2oz are mostly used in consumer and communication products. Thick copper products above 3oz are mostly used for high currents, such as high-voltage products and power boards.

The thickness of copper foil (track width) will affect the current size. Although there is a formula that can directly calculate the maximum current carrying capacity of copper foil, it is not so simple when actually designing the circuit. Therefore, the safety factor should be fully considered during the design.

How thick is the copper in a flex PCB?

The thickness of copper foil in flexible PCB is generally 18μm, 35μm, 55μm and 70μm. These thickness specifications are suitable for different types of circuit board requirements, among which 35μm is the most commonly used copper foil thickness.

For flexible PCB, the choice of copper foil thickness depends on the specific purpose of the circuit board and the size of the signal voltage and current. For example, for PCBs that require excessive current, some parts will use 70μm copper thickness, while for signal transmission, 1oz (35μm) thickness is usually sufficient. In addition, for substrates of different thicknesses, the thickness of copper foil is also different. For example, the thickness of the composite copper foil on a 1mm thick substrate is about 18μm, and on a substrate thicker than 5mm, the thickness of the composite copper foil is about 55μm.

Conclusion:

PCBs for different usage scenarios correspond to different thicknesses of copper, and its thickness directly affects the conductive effect of the circuit board. If the copper layer is too thin, the conductivity may decrease, resulting in signal transmission attenuation or current instability. If the copper layer is too thick, although the conductivity will be very good, it will increase the cost and weight of the circuit board and easily lead to serious glue flow. In PCB manufacturing, it is necessary to select the appropriate copper thickness according to the design requirements and actual applications of the circuit board to achieve the best conductive effect.

BEST Technology is a professional PCB circuit board manufacturer with a large area of site and equipped with useful and experienced production personnel. Corresponding to different thicknesses of copper, we have rich production and processing experience. We can meet the requirements of any circuit board copper layer thickness.‌

Tags: heavy copper pcb, PCB, PCBA, printed circuit board
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What is SMT Process in PCB Manufacturing? – Best Technology

August 14th, 2024

SMT process is one of the most commonly used processes in PCBA or box build assembly products. It also called surface mount process. It is reliable connection between electronic components and printed circuit boards can be realized through the precise mounting and welding technology of the SMT machine.

What is an SMT Process?

The SMT process is a method used to mount electronic components directly onto the surface of a printed circuit board (PCB). Unlike traditional through-hole technology, where components are placed in drilled holes, SMT components are placed on the board’s surface.

SMT enables the creation of smaller devices without compromising performance. By eliminating the need for drilled holes, it also speeds up production, reducing costs and improving efficiency.

What is SMT Process in PCB Manufacturing? - Best Technology

What is the Purpose of SMT?

The primary purpose of SMT is to streamline the manufacturing process while enhancing the functionality and reliability of electronic devices. SMT allows manufacturers to produce smaller, more complex circuits that are essential for today’s technology-driven world. From smartphones to medical devices, SMT plays a critical role in the development of products that we rely on daily.

Moreover, SMT offers flexibility in design, allowing engineers to create intricate circuits that would be impossible with traditional methods. The process also supports higher levels of automation, reducing the risk of human error and ensuring consistent quality across large production runs. In essence, SMT is about improving efficiency, quality, and innovation in electronics manufacturing.

Terms Related to SMT

Solder Paste

A mixture of powdered solder and flux used to bond SMT components to the PCB. It’s applied to the board using a stencil and is essential for creating strong, reliable connections.

Pick and Place Machine

An automated machine that picks up components and places them onto the PCB with high precision. This machine is vital in ensuring that components are positioned accurately before soldering.

Reflow Oven

After the components are placed on the PCB, the board is passed through a reflow oven. The heat melts the solder paste, securing the components in place.

Stencil

A metal or plastic template used to apply solder paste to specific areas of the PCB. The stencil ensures that the paste is only applied where needed, preventing defects.

Flux

A chemical agent that cleans the surfaces of the components and the PCB, ensuring a strong bond during the soldering process.

PCB

The bare board without any components on its surface. The board that serves as the foundation for electronic components. It has conductive pathways that connect the components and allow them to function together.

PCBA

When a PCB is surface-mounted or through-hole-mounted with components, we call this semi-finished product a PCBA. It can further assemble with other PCBAs and an enclosure to become a complete product or box-build we call it.

SMD

Surface mount device, it is an electronic component for SMT manufacturing. Compared with PTH components for PTH assembly, SMDs have a much smaller weight and size about 1/10 of a PTH component of the same function.

How Many Steps are in the SMT Process?

The SMT process involves several detailed steps, each essential for ensuring the quality and reliability of the final electronic product. Below is a comprehensive look at these steps:

Step 1: Components Incoming Inspection

Before the assembly begins, all components undergo an incoming inspection. This step is crucial to ensure that all parts meet the required specifications. It helps in identifying any defects or discrepancies in the components, which could affect the final product’s quality.

Step 2: PCB Quality Control

The next step is to inspect the PCB itself. This involves checking for any manufacturing defects, such as scratches, misalignments, or irregularities in the copper layers. Ensuring the PCB is flawless is vital because any defect can lead to failure in the final assembly.

Step 3: Stencil Preparation

Stencil preparation is critical for the accurate application of solder paste. The stencil must be aligned correctly with the PCB to ensure the solder paste is applied precisely to the pads where components will be placed. This accuracy is key to avoiding soldering defects.

Step 4: Solder Paste Applying

Solder paste is applied to the PCB through the stencil. The paste contains tiny balls of solder mixed with flux, and it’s applied to the areas where components will be soldered. Proper application of the solder paste is essential for creating reliable solder joints.

Step 5: SPI (Solder Paste Inspection)

After applying the solder paste, it’s inspected using SPI (Solder Paste Inspection) equipment. This step checks the volume, height, and position of the solder paste on the PCB. Any deviations from the ideal paste deposit can lead to defects, so this inspection helps ensure consistency and quality.

Step 6: Pick and Place Components

The pick and place machine automatically places components onto the PCB. Misplaced components can lead to electrical failures, so this step is critical for the overall success of the process.

Step 7: Reflow Soldering

Once the components are placed, the PCB is passed through a reflow oven. The heat in the oven melts the solder paste, creating a solid electrical connection between the components and the PCB. The reflow process must be carefully controlled to avoid overheating or insufficient soldering.

Step 8: AOI (Automated Optical Inspection)

After reflow soldering, the board undergoes AOI. This inspection process uses cameras to check for soldering defects, such as bridges, misaligned components, or insufficient solder. AOI helps catch defects early, reducing the chances of failures in the final product.

Step 9: X-RAY (Only for BGA or Fine-Pitch Components)

For boards with Ball Grid Array (BGA) or fine-pitch components, an X-ray inspection is performed. This step allows for the inspection of solder joints that are hidden beneath the components, ensuring that they are properly formed and free of defects.

Step 10: FAI (First Article Inspection)

The first board produced in a batch undergoes FAI, where it is thoroughly inspected to ensure that all processes and setups are correct. This step serves as a final check before full production begins, helping to confirm that everything is in order.

Step 11: Function Testing

The final step in the SMT process is function testing. This involves testing the completed PCB to ensure it functions as intended. Function testing is essential to verify that the board meets the required specifications and operates correctly in its intended application.

SMT Process Flow Chart

A flow chart is a visual representation of the SMT process, showing each step in sequence. This chart is essential for understanding how the process works and identifying potential areas for improvement. Here’s a basic flow chart of the SMT process:

How Do I Prepare for SMT?

Preparing for the SMT process requires careful planning and attention to detail. Here are some tips to help you get ready:

Design for Manufacturability (DFM)
Material selection
Stencil
Equipment calibration
Quality control
Training

Best Technology – Your Turn-key PCB & PCBA Supplier

At Best Technology, we offer a range of value-added services, including IC programming, functional testing, conformal coating, thermal aging, and box-build assembly, ensuring you receive fully assembled and ready-to-use electronic products.

Additionally, you can reduce fabrication costs without compromising on function or quality. If needed, Best Technology can source alternative components with equivalent functions and certifications to replace more expensive parts as well.

Tags: smt process, surface mount process
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TDA7294 Amplifier Board: A Comprehensive Introduction

August 13th, 2024

The TDA7294 amplifier board is a functional and widely used audio amplifier. It is based on the TDA7294 integrated circuit (IC), a high-power, low-distortion audio amplifier IC developed by STMicroelectronics. This IC is designed to deliver high-quality audio output with minimal distortion, making it a popular choice for DIY audio enthusiasts and professionals alike.

What is TDA7294 IC Amplifier Board?

The TDA7294 IC is capable of delivering up to 100 watts of power in a single-ended or bridged configuration, making it suitable for a wide range of audio applications, from home audio systems to professional audio equipment. The amplifier board typically includes the TDA7294 IC along with supporting components such as capacitors, resistors, and heatsinks, all mounted on a printed circuit board (PCB). This board is designed to simplify the process of building a powerful and reliable audio amplifier by providing a pre-configured layout that ensures optimal performance.

TDA7294 Amplifier Board: A Comprehensive Introduction

Features of TDA7294 Amplifier Board

The TDA7294 amplifier board provides several key features that make it a popular choice for high-quality audio amplification.

High Output Power
Low Distortion
Built-in Protection Circuits
Thermal Management
Low Noise and High Signal-to-Noise Ratio (SNR)
Ease of Integration
Flexible Configuration
Improved Reliability
Compact Size

TDA7294 Amplifier Circuit Diagram

The circuit diagram of the TDA7294 amplifier is a crucial element for anyone looking to build or understand this amplifier. The diagram typically includes the TDA7294 IC at the core, surrounded by components that shape the audio signal and manage power delivery. Key components include capacitors for signal coupling and power supply smoothing, resistors for setting gain and biasing, and inductors or filters for noise reduction.

The TDA7294 IC itself has several pins that serve specific functions in the circuit. For instance, the input pin receives the audio signal, while the output pin sends the amplified signal to the speakers. Power supply pins connect to the positive and negative voltage rails, and other pins might be used for muting, standby, or feedback purposes.

When assembling the circuit, careful attention must be paid to the placement of components and routing of traces on the PCB to minimize noise and maximize performance. The layout of the circuit diagram ensures that the amplifier delivers clean, high-fidelity sound with minimal distortion, which is a key selling point for the TDA7294.

TDA7294 Specification

Symbol	Parameter	Test condition	Min. value	Typical value	Max. value	Unit
Vs	Power Supply		±10		±40	V
lq	Current Consumption		20	30	60	mA
Vos	Input Offset Voltage				500	mV
los	Input Offset Current				±100	nA
Po	Continuous Power Output	VS = ± 35V, RL = 8Ω; VS = ± 31V, RL = 6Ω; VS = ± 27V, RL = 4Ω;	60	70		W
d	THD	PO = 5W; f = 1kHz PO = 0.1 to 50W; f = 20Hz to 20kHz		0.005	0.01	%
d	THD	VS = ±27V, RL = 4W: PO = 5W; f = 1kHz PO = 0.1 to 50W; f = 20Hz to 20kHz		0.01	0.01	%
SR	Switching rate		7	10		V/us
Gv	Open Loop Voltage Gain			80		dB
Gv	Closed Loop Voltage Gain		24	30	40	dB
fL, fH	Frequency Response (-3dB)	Po=1W	20Hz to 20kHz
Ri	Input Resistance		100			KΩ

TDA7294 Pinout

The TDA7294 IC comes with a specific pinout configuration that plays a crucial role in its operation. The chip has 15 pins, each with a designated function:

Pin 1 (IN+): Non-inverting input

Pin 2 (SVR): Supply voltage rejection

Pin 3 (IN-): Inverting input

Pin 4 (MUTE): Mute function

Pin 5 (ST-BY): Standby function

Pin 6 (VCC+): Positive supply voltage

Pin 7 (OUT): Output

Pin 8 (GND): Ground

Pin 9 (BOOTSTRAP): Bootstrap capacitor

Pin 10 (NC): Not connected

Pin 11 (VCC-): Negative supply voltage

Pin 12 (DIAG): Diagnostics pin

Pin 13 (BOOTSTRAP): Bootstrap capacitor

Pin 14 (GND): Ground

Pin 15 (OUT): Output

TDA7294 Datasheet

The TDA7294 datasheet is a critical resource for anyone working with this IC. It provides detailed information about the IC’s electrical characteristics, pin configurations, thermal properties, and recommended operating conditions. The datasheet also includes typical application circuits, which can serve as a starting point for designing your own amplifier.

In addition to technical specifications, the datasheet often includes practical advice on PCB layout, component selection, and thermal management. Following these guidelines can help you achieve the best possible performance from your TDA7294 amplifier board.

How Many Watts is a TDA7294 Output?

The TDA7294 IC is capable of delivering up to 100 watts of output power when configured in a single-ended or bridged amplifier circuit. The actual output power depends on several factors, including the supply voltage, load impedance, and heat dissipation. In a typical configuration with a supply voltage of ±35V and an 8-ohm load, the TDA7294 can deliver around 70 watts of continuous power.

For higher power output, the IC can be used in a bridged configuration, where two TDA7294 ICs are combined to drive a single load. In this setup, the output power can reach up to 150 watts, making it suitable for driving larger speakers or subwoofers.

It’s important to note that the power rating of the TDA7294 should be matched to the speakers and other components in your audio system. Overloading the IC by driving it at maximum power for extended periods can lead to overheating and potential damage, so proper thermal management is essential.

What is the Equivalent of TDA7294?

When looking for an equivalent to the TDA7294, there are a few other audio amplifier ICs that offer similar performance characteristics. Some of the commonly considered alternatives include:

LM3886

This is another high-power audio amplifier IC that delivers up to 68 watts of output power. It’s known for its low distortion and high fidelity, making it a popular choice for DIY audio projects.

TDA7293

This IC is very similar to the TDA7294, with slightly different electrical characteristics. It can be used as a drop-in replacement in many circuits, offering similar power output and performance.

TDA2030

While not as powerful as the TDA7294, this IC is a good alternative for lower-power applications. It delivers up to 20 watts of output power and is widely used in small audio amplifier projects.

Each of these alternatives has its strengths and weaknesses, so the best choice depends on the specific requirements of your project. For instance, if you need higher output power, the LM3886 might be a better option, while the TDA2030 is more suitable for compact, low-power designs.

What is the Maximum Voltage for TDA7294 IC?

The maximum supply voltage for the TDA7294 IC is ±50V. However, for optimal performance and reliability, it’s recommended to operate the IC at a lower voltage, typically around ±35V to ±40V. Operating at the maximum voltage can increase the risk of overheating and may require additional cooling measures, such as larger heatsinks or active cooling.

The voltage rating is crucial for ensuring the longevity and performance of the amplifier. Exceeding the maximum voltage can cause the IC to fail, leading to permanent damage. Therefore, it’s important to choose a power supply that matches the recommended voltage range for the TDA7294.

In addition to the supply voltage, the IC’s thermal management is also important. Ensuring adequate cooling through heatsinks or ventilation can prevent overheating and ensure stable operation, especially when driving the amplifier at high power levels.

What is TDA in an Amplifier?

The TDA prefix in TDA7294 refers to the series of audio amplifier ICs developed by STMicroelectronics. These ICs are designed to provide high-quality audio amplification with minimal distortion and noise. The TDA series includes a range of ICs with varying power output capabilities, making them suitable for different audio applications, from small portable speakers to large home audio systems.

In an amplifier, the TDA IC is responsible for amplifying the audio signal from a low-level input to a high-level output that can drive speakers. The IC’s internal circuitry is optimized for audio performance, ensuring that the amplified signal remains clear and distortion-free.

The TDA series is widely regarded for its reliability and performance, making it a popular choice for both commercial and DIY audio projects. Whether you’re building a simple audio amplifier or a more complex audio system, the TDA7294 and its counterparts offer a solid foundation for high-quality sound.

FAQs

1. Can the TDA7294 be used in a car audio system?

Yes, the TDA7294 can be used in car audio systems, but you need to ensure that the power supply provides the correct voltage and current. Car audio systems typically operate at 12V, so a step-up converter might be needed to reach the required supply voltage.

2. How do I connect multiple TDA7294 ICs for higher power output?

You can connect multiple TDA7294 ICs in a bridged configuration to increase the power output. This involves using two ICs to drive a single load, effectively doubling the output power.

3. What is the typical distortion level of the TDA7294?

The TDA7294 has a low distortion level, typically around 0.005% at 1kHz, making it suitable for high-fidelity audio applications.

4. Is the TDA7294 suitable for subwoofers?

Yes, the TDA7294 is suitable for driving subwoofers, especially in a bridged configuration where it can deliver high power output with low distortion.

5. Can I use the TDA7294 with a passive cooling system?

While the TDA7294 can be used with a passive cooling system, it’s important to ensure that the heatsink is large enough to dissipate the heat generated during operation. For higher power levels, active cooling may be necessary to prevent overheating.

Tags: TDA7294, tda7294 amplifier board
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Rigid flex pcb Design & Prototype Right the First Time

August 12th, 2024

rigid-flex printed circuit board ,Rigid flex pcb manufacturer. More than 5 years design team of 10 people. Quick proofing within 1 week. A 3,000-square-meter factory for small batch to mass production and assembly.

What is a rigid flex pcb?

Rigid flex pcb,rigid-flex printed circuit board，Rigid flex circuit are a hybrid construction flex circuit consisting of rigid and flexible substrates which are laminated together into a single structure. Each layer of rigid-flex circuit are electrically interconnected by plated through holes (PTH), which is different from a flexible circuit with FR4/PI stiffener on top or bottom of flex circuit only by the means of presensive or thermal senstive adhesive only, no PTH.

Rigid-flex PCBs can be divided into single-sided boards, double-sided boards and multi-layer boards according to the number of conductive circuit layers. Multi-layer boards usually contain multiple rigid layers and flexible layers, and the circuits are connected and interconnected through interlayer connections.

Is Rigid flex PCB reliable?

Design and manufacturing efficiency: Designers of rigid-flex boards can use a single component to replace a composite printed circuit board connected by multiple connectors, multiple cables and ribbon cables, which not only has stronger performance and higher stability, but also limits the scope of the design to one component, optimizing the available space by bending and folding the lines like a stacked paper swan.
Space and weight optimization: In PCB prototyping for consumer electronics, the use of rigid-flex boards not only maximizes space use and minimizes weight, but also greatly improves reliability, eliminating many needs for solder joints and fragile and fragile wiring that are prone to connection problems. The design of this circuit board allows the size and weight of equipment and systems to be reduced while maintaining functionality.
High stress environment adaptability: Rigid-flex boards also have high impact resistance and can survive in high stress environments, which makes it widely used in military, aviation and medical equipment.
Excellent electrical performance: Rigid-flex boards provide excellent electrical performance, and good thermal conductivity makes components easy to cool. The lower dielectric constant of the flexible part allows for fast transmission of electrical signals, and the PI substrate has a higher glass transition temperature or melting point, which allows the components to operate well at higher temperatures.
Assembly reliability: Rigid-flex boards reduce the hardware required for traditional rigid boards and flexible boards to be connected, such as traditional jumper sockets, etc., and can provide higher assembly reliability.

What is the difference between rigid flex and semi flex?

Definition and structure
Rigid-flexible board: It is a combination of soft board and hard board, that is, a thin layer of flexible bottom layer and rigid bottom layer are combined and laminated into a single component to form a circuit board1. It changes the traditional flat design concept and expands it to a three-dimensional space concept. It has both rigid layer and flexible layer and is a multi-layer printed circuit board.
Semi-flexible board: It is a PCB used in the field of static bending obtained by combining controlled deep milling or rigid-flexible board processing technology (such as milling cover or opening window, etc.) in the standard hard board processing process2. It often uses FR4 material, first processes the PCB according to the normal process, and then mills the middle part that needs to be bent to make it flexible.
Flexibility and application
Rigid-flexible board: It has higher flexibility and can be bent, folded or rounded, and then integrated into various products, such as aerospace equipment, military aircraft, high-end medical equipment, digital cameras, portable cameras and high-quality MP3 players. ‌
Semi-flexible board: Although it can be bent or curved, its flexibility is not as good as that of rigid-flexible board. It is mainly used in situations where static bending is required, such as endoscopes in medical equipment, injection needle tip protection circuit boards, and medical equipment temperature control circuit boards. ‌
Processing and cost
Rigid-flexible board: Due to the mixed use of multiple materials and multiple production steps, its processing time is longer and the production cost is higher. ‌
Semi-flexible board: Although its processing process is also more complicated, its processing cost is lower than that of rigid-flexible board, and it is more suitable in some applications. ‌
Features and advantages
Rigid-flexible board: It has stronger performance and higher stability, can reduce space and weight, and improve the reliability of connection. ‌
Semi-flexible board: It has the advantages of low cost, good dimensional stability, bendable three-dimensional installation to reduce space, and reduce the number of interfaces during assembly to improve reliability.‌

how do they add rigid layers to flex pcb?

Design layout: Before starting the manufacturing process, the PCB design layout is first carried out to determine the location and connection method of the components. ‌
Substrate preparation: Clean the laminate containing the copper layer to prepare for the subsequent manufacturing process. ‌
Pattern generation: The generation of circuit patterns is completed by screen printing or photo imaging. ‌
Etching process: The laminate with the circuit pattern is soaked in an etching tank or sprayed with an etchant solution for etching. ‌
Mechanical drilling: Circuit holes, pads and via patterns are drilled using a precision drilling system or technology, such as laser drilling technology. ‌
Copper plating process: Deposit the required copper in the plated vias to establish electrical interconnections between layers. ‌
Covering layer application and lamination: Apply the covering layer material (such as polyimide film) and adhesive, and laminate under specific temperature, pressure and vacuum limits to ensure proper adhesion of the covering layer. ‌
Apply stiffeners: Apply local additional stiffeners before additional lamination processes as required by the board design. ‌
Flexible board cutting: Cut flexible boards from production panels using hydraulic punching methods or specialized punching knives. ‌
Electrical testing and verification: Conduct electrical testing in accordance with IPC-ET-652 guidelines to confirm that the insulation, connection, quality, and performance of the circuit board meet the requirements of the design specifications.

What are the disadvantages of rigid flex PCB?

Material damage or breakage: The flexible materials used in rigid-flex boards are susceptible to flexure and bending. Long-term use or improper handling may cause damage or breakage of the flexible part, resulting in an open circuit.
Poor welding: The manufacture of rigid-flex boards requires welding processes. If the welding is poor or the solder joints are of poor quality, it may cause loose connections or solder joints to fall off, resulting in an open circuit.
Excessive bending or stretching: Excessive bending or stretching during use may cause the connection wires or wires of the flexible part to be stretched excessively and break, causing an open circuit.
Design defects: If the design of the rigid-flex board is unreasonable or defective, such as insufficient design of the overbending area or too small bending radius, the material of the flexible part may be damaged by excessive stress, resulting in an open circuit.
Environmental factors: Under different environmental conditions, it may be affected by factors such as temperature, humidity, and chemicals. Long-term use in harsh environments may cause material aging or corrosion, resulting in an open circuit. ‌
Damage during assembly: During the assembly process, improper operation or external force may cause damage to the connecting wires or wires of the flexible part, resulting in an open circuit.

Application fields of rigid flex PCB

Automotive electronics: Rigid-flex boards are widely used in automotive electronic systems such as dashboards, navigation systems, and in-car entertainment systems in the automotive industry. Their flexibility and high reliability enable them to adapt to the complex spatial layout and vibration environment inside the car.
Medical equipment: In the field of medical equipment, rigid-flex boards also have important applications, such as medical monitoring equipment, medical imaging equipment, etc. Its flexible part can adapt to different equipment shapes and size requirements, while having stable circuit connection performance.
Aerospace field: Rigid-flex boards are usually used in aircraft dashboards, navigation systems, communication equipment, etc. in the aerospace field. Due to their light, thin and flexible characteristics, rigid-flex boards have become an ideal choice for aerospace equipment.
Smart wearable devices: With the rapid development of smart wearable devices, rigid-flex boards are widely used in products such as smart watches and health monitoring equipment. They can be combined with curved display screens, sensors and other components to achieve a more humanized design.
Industrial control field: In the field of industrial automation control, rigid-flex boards are often used in PLC controllers, robot control systems, sensor interfaces, etc. Its flexibility and reliability ensure the stable operation of the equipment in harsh environments.

Rigid flex pcb manufacturer

rigid flex pcb.rigid-flex printed circuit board，Rigid flex circuit are a hybrid construction flex circuit consisting of rigid and flexible substrates which are laminated together into a single structure. Each layer of rigid-flex circuit are electrically interconnected by plated through holes (PTH), which is different from a flexible circuit with FR4/PI stiffener on top or bottom of flex circuit only by the means of presensive or thermal senstive adhesive only, no PTH.

Multilayer circuitry-from 3 to 14+ layers
Min LW/LS: 4mil/4mil
Adhesive-based and adhesiveless constructions, including thermoplastic and thermoset stiffener attachment.
Polyimide substrates: 1/2mil – 4mil
Copper: 1/3OZ – 2OZ, RA or ED type
Stiffeners include Polyimide (0.075-0.20mm), FR4 (0.15-2.0mm), and punched or formed metal parts (0.075-1.0mm)
Low-cost, conventional fabrication and lamination completed with PTH based plating
Screened inks, photo-imageable soldermasks, or laminated coverlay dielectrics
Surface finishes: ENIG, electroplated nickel/gold, immersion silver, tin,
EMI Shielding

how to design flex rigid pcb?

Rigid-Flex Circuit Design Guidelines

To form a rigid-flex, follow these considerations to ensure the best results.

Considerations When Designing Rigid-Flex Circuits

To produce a rigid-flex PCB with unmatched quality and functionality, you must follow the correct manufacturing specifications. This is the set guidelines and standards that manufacturers must consider when designing and manufacturing flexible circuit boards.

Determine Manufacturing Process and Materials Beforehand

Depending on the flexibility you require, you need to decide beforehand what materials to use and the methods to use. Example; When the board you are designing only needs to be folded during manufacturing and thereafter be in a fixed position without bending, you can decide the following

Copper type and grade
Manufacturing method
Number of layers to be used.

On the other hand, if the board is for an application with frequent movement, vibration, and impact, you must be clear in choosing the following:

Copper Coils
Adhesives and
Number of Layers

Place Copper Traces at Right Angles to Rigid-Flex

Copperworks is a great fit when placed on the right edge of the board. Avoid bending copper traces at corners as it will pull stress and may not create the best bend. For PCB flex that requires bending, use sharp radius bends to avoid smudging copper traces.

Provide adequate pad support for exposed copper

Repetitive stress from frequent bending can cause copper on the circuit to break away from the polyimide substrate. Support exposed copper with pads to prevent separation.

Use hatched polygons

Hatched polygons instead of solidified copper help maintain the flexibility of flexible PCBs.

Leave at least 1/2mm gap between copper ring and adjacent vias

1/2mm helps avoid fatigue caused by frequent bending. Placing vias in fixed areas of the board helps avoid frequent movement and bending, resulting in the best rigid-flex.

Tags: PCB, PCBA
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What Does An Audio Board Do? – Best Technology

August 9th, 2024

An audio board, often referred to as a soundboard or mixer, is a crucial device in the world of sound engineering. Whether you’re working on a live concert, recording in a studio, or simply enhancing audio for a video production, understanding the role of an audio board is essential. This guide will walk you through what an audio board does, its various names, and how to set one up effectively.

What Does an Audio Board Do?

An audio board, or soundboard, manages and controls audio signals. It’s used in many settings, from live concerts to recording studios. The primary function of an audio board is to mix different audio sources, such as microphones and instruments, to create a balanced sound output. This device allows sound engineers to adjust levels, equalize sound frequencies, and add effects to enhance the overall audio experience.

In more technical terms, an audio board receives input signals, processes them, and sends them to an output device. This processing can include adjusting volume levels, panning audio between speakers, and applying effects like reverb or delay. The result is a well-mixed audio output that sounds harmonious and professional.

What is Also Called an Audio Board?

An audio board goes by several names, depending on its use and context. Commonly, it’s known as a soundboard or mixing console. In professional settings, you might hear it referred to as an audio mixer or sound mixer. These terms are often used interchangeably, but they all refer to the same essential device that manages and manipulates audio signals.

Other names include audio mixing board and professional mixing board. These names highlight the device’s role in combining multiple audio inputs into a single or multiple outputs. Whether you’re shopping for an audio board online or looking to upgrade your studio equipment, understanding these terms will help you find the right product for your needs.

What is the Working Principle of Audio Board?

The working principle of audio circuit refers to the process of audio signal transmission and processing in the circuit. In general, the frequency range of audio signals is 20Hz to 20kHz, and they are electrical signals used to transmit sound. The processing of audio signal includes amplification, mixing, filtering and so on.

Amplification refers to increasing the amplitude of the audio signal so that it can drive the speaker to produce a sound. The amplification process is generally achieved using an amplifier, the principle is to use the amplifier tube of the amplifier to amplify the input signal and then output it to the speaker.

Mixing refers to the process of mixing multiple audio signals into one signal. In a mixing circuit, multiple audio signals are mixed together through a mixer to output a composite signal. The mixer is generally composed of an operational amplifier and a mixer. The operational amplifier is responsible for adding multiple input signals, while the mixer is responsible for adjusting the volume ratio of each input signal.

Filtering refers to filtering the audio signal through a filter to remove unwanted frequency components. Filters are generally divided into low-pass filters, high-pass filters and band-pass filters. A low-pass filter only allows low-frequency signals to pass through, a high-pass filter only allows high-frequency signals to pass through, and a bandpass filter only allows signals in a certain frequency range to pass through.

Is a Sound Board the Same as a Mixer?

Yes, a soundboard and a mixer are essentially the same device. Both terms describe equipment used to blend and adjust audio signals. The term “mixer” is often used in professional audio production environments, while “soundboard” is more common in live sound settings.

The confusion between these terms arises from their varied applications. A soundboard is typically associated with live events, where audio engineers manage the sound in real-time. A mixer, on the other hand, might be used more broadly, encompassing both live and studio environments. Regardless of the term, the device’s primary function remains the same: to mix audio signals and produce a balanced sound output.

What is the Function of a Soundboard?

A soundboard, or audio mixer, plays a critical role in sound engineering by managing and manipulating audio signals. Let’s delve deeper into its functions:

Mixing Audio Signals
Equalization (EQ)
Volume Control
Panning
Adding Effects
Routing
Dynamic Processing
Monitoring

How Do You Hook Up a Soundboard?

Hooking up a soundboard needs to proceed several steps. Each step is the key point to make sure all audio sources are correctly connected and configured. Here’s a step-by-step guide:

Prepare all necessary cables, microphones, instruments, and speakers.
Plug your microphones and instruments into the input channels on the soundboard. Each channel corresponds to a specific input source.
Connect the output channels of the soundboard to your speakers or recording devices. This usually involves using XLR or quarter-inch cables.
Turn on the soundboard and all connected equipment.
Adjust the input gain for each channel to ensure the signal is neither too weak nor too strong.
Test each input and output to ensure everything is working correctly. Make necessary adjustments to the levels and EQ settings.
Use headphones or monitor speakers to listen to the audio and make final adjustments.

How to Set Up a Sound Mixing Board?

Setting up a sound mixing board involves more than just connecting cables. Here are detailed steps to set up your sound mixing board effectively:

Plan Your Setup

Determine the layout of your equipment and where each input and output will be connected. This planning stage helps avoid confusion during the actual setup.

Label Everything

Label each input and output cable to know which source they correspond to. This step is crucial in complex setups with many audio sources.

Connect Your Inputs

Plug in microphones, instruments, and any other audio sources into the appropriate input channels on the mixing board.

Connect Your Outputs

Connect the main outputs to your speakers or PA system. Also, connect any auxiliary outputs to additional monitors or recording devices.

Power Everything On

Turn on your mixing board and connected equipment. Make sure to power on any external preamps or processors first if you’re using them.

Adjust Gain Levels

Set the gain for each input channel. Start with the faders at unity (0 dB) and adjust the gain until each input is at a proper level.

Set EQ and Effects

Adjust the EQ settings for each channel to achieve a balanced sound. Add effects as needed to enhance the audio.

Create a Mix

Use the faders to balance the levels of all input sources. Make sure each source is heard clearly without overpowering the others.

Monitor and Adjust

Continuously monitor the sound through headphones or monitor speakers. Make adjustments as necessary to maintain a balanced mix.

Best Technology has rich experience in the audio board manufacturing, we have served more than 2000+ customers and provide excellent turn-key solutions. If you are interested in the audio board pcb assembly, welcome to contact us.

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hs code printed circuit board,pcb boards hs code

August 9th, 2024

The customs code for printed circuit boards is 8534-0000. 8534 is the classification code for this item, and 0000 represents the sub-classification code under this item. In the actual customs declaration process, it is necessary to select the corresponding sub-classification code according to the specific classification standard of printed circuit boards.

hs code printed circuit board：85340000
PCBs made of FR-4 material (i.e. silicon tetrachloride fiberglass board) are classified under HS code 8534.00.00
hs code printed circuits with more than six layers：85340010
hs code printed circuits with four layers or less:85340090
The HS code for PCB (printed circuit board) is 8534001000.
HS code of PCBA is 8543709990

How do you classify printed circuit boards?

According to different classification standards, printed circuit boards can be divided into many types, such as single-sided boards, double-sided boards, multi-layer boards, rigid boards, flexible boards, etc.

The role of HS codes for printed circuit boards

HS codes are a way for customs to classify goods, and are also an important basis for import and export statistics. As an electronic component, printed circuit boards also need to be HS coded so that customs can accurately classify and manage them.

Types of HS codes for printed circuit boards

There are two main HS codes for printed circuit boards: 85340010 and 85340090. Among them, 85340010 is mainly used for printed circuits with more than six layers, while 85340090 is mainly used for printed circuits with four layers or less. The difference between the two codes lies in the number of layers of the printed circuit board, because printed circuits with more than six layers require higher technical requirements and more complex production processes.

How to choose the correct HS code

The specific HS code may vary depending on product specifications, materials and other factors. Therefore, in actual operation, it is recommended to consult relevant departments or professionals according to the specific situation to ensure accuracy. If you are not sure which HS code to choose, you can consult the printed circuit board manufacturer or relevant industry associations for more professional advice.

How do I do a customs declaration?

Declare the code accurately. Select the sub-classification number corresponding to the printed circuit board according to the actual situation to avoid penalties or detention caused by coding errors.
Provide a complete production process. The production process of the printed circuit board needs to be provided in the customs declaration, including the procurement, production, processing, testing and other links of the materials, so as to facilitate the customs inspection of the printed circuit board.
Declare accurate materials and technical parameters. The technical parameters such as the substrate, copper foil thickness, board thickness, drilling diameter, line width, line spacing, etc. used in the printed circuit board need to be accurately declared in the customs declaration.
Re-declaration is required if the dominant production process is changed. If the dominant production process is changed, it is necessary to re-declare to the customs and re-make the customs declaration.
Comply with relevant national quality standards. Printed circuit boards need to meet relevant national quality standards, such as ISO, UL, etc.

hs code electronic,How do I find an HS code?The HS code for PCB (printed circuit board) is 8534001000. PCBs made of FR-4 material (i.e. silicon tetrachloride fiberglass board) are classified under HS code 8534.00.00

Tags: HS CODE
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How to Read Circuit Boards and Schematics?

August 7th, 2024

How to read circuit boards and schematics is a basic skill for anyone interested in electronics. Whether you’re a beginner or a technician, knowing how to read these diagrams is crucial. In this blog, we would like to share the key points and components symbols in the PCB schematics.

How to Understand a PCB Board?

A printed circuit board is a basic of electronic components interconnected via conductive paths printed on a baseboard. We can see it everywhere. They connect and support various components using conductive tracks, pads, and other features. To understand a PCB, start by identifying its main sections: power supply, signal paths, and grounding. Look for the layout patterns, which often follow a logical flow.

Special Types of Circuit Boards

Circuit boards come in various types, each designed for specific applications and processes. Apart from the standard FR4 PCB, metal core PCB, ceramic PCB, rigid-flex PCB, there are some other special PCB uses different process. Here, we’ll explore them based on their unique manufacturing processes, including HDI, busbar, extra thin, IC substrate, high Tg, heavy copper, RF, and impedance control PCBs.

High-Density Interconnect (HDI) PCB

HDI PCBs are designed for compact and complex electronic devices. They feature higher wiring density per unit area compared to traditional PCBs. The process involves microvias, buried vias, and blind vias to create intricate pathways. HDI technology allows for more components on a smaller board, enhancing performance and reducing size. This type of PCB is commonly used in smartphones, tablets, and other high-tech gadgets. The HDI PCBs that Best Technology can make is:

1+N+1
2+N+2
3+N+3

Busbar PCB

Busbar PCBs are specialized boards that handle high current loads efficiently. It belongs to the heavy copper PCB. They use thick copper layers to conduct electricity with minimal resistance. The busbar process involves integrating these thick copper bars within the PCB to distribute power uniformly. They are mainly used in the electric vehicles, power supplies and industrial machinery.

Extra Thin PCB

Extra thin PCBs are designed for applications where space and weight are critical constraints. These boards can be as thin as 0.2mm, allowing them to fit into slim devices like wearables and medical implants. The manufacturing process focuses on using thinner materials and precision etching techniques to achieve the desired thickness without compromising functionality.

IC Substrate PCB

IC substrate PCBs act as the base for integrated circuits (IC). They provide interconnections between the IC and the PCB. These PCBs are crucial in devices like processors, memory modules, and graphic cards, where precision and reliability are paramount.

High Tg PCB

High Tg (glass transition temperature) PCBs are designed to withstand higher temperatures. The Tg value indicates the temperature at which the PCB material transitions from a rigid to a soft state. High Tg PCBs use materials that has over 170 Tg value. So, they are widely used in automotive, aerospace, and industrial applications.

Heavy Copper PCB

Heavy copper PCBs feature significantly thicker copper layers compared to standard PCBs. The process involves plating additional copper to achieve thicknesses of 3oz/ft² or more. These boards handle high currents and thermal cycles, making them ideal for power electronics, motor controllers, and high-power distribution systems.

Radio Frequency (RF) PCB

RF PCBs are designed for high-frequency applications. They use special materials like PTFE (Teflon) to minimize signal loss and interference. This kind of PCB always requires precise control over dielectric thickness and conductor widths to make sure optimal signal integrity. RF PCBs are essential in communication devices, radar systems, and microwave equipment.

What Do the Numbers on a Circuit Boards Mean?

Numbers and letters on a circuit board represent component values, reference designators, and sometimes manufacturing codes. Reference designators (like R for resistors, C for capacitors) help identify each component. The numbers often indicate the order of placement or specific values (e.g., R1, R2 for the first and second resistors).

In addition, some designers prefer to design series number on the PCB board, like 202400001…202400002. For this kind of numbers, they are always aim to easy identification during the assembly or testing.

How to Read Circuit Boards?

Reading a circuit board involves several steps. First, familiarize yourself with the board’s layout and components. Identify key parts such as the microcontroller, resistors, capacitors, and connectors. Trace the pathways or traces to understand the connections. Use the reference designators to match components with their schematic symbols.

Electronic symbols follow standardized guidelines to ensure consistency. The most common standards include IEEE, IEC, and ANSI. These symbols represent various components like resistors, capacitors, diodes, and transistors.

VCC – the positive power supply.
GND – ground or negative power supply.
R – resistor.
C – capacitor.
L – inductor.
Q – transistor or field-effect transistor (FET).
JP – connector or plug/socket.
IC – integrated circuit or chip.
+ / – – input/output terminals of a signal.
NC – no connection or an unused pin.

How Do You Read a Circuit Schematic for Beginners?

Read circuit diagram drawings can be consulted by experienced masters. Generally, the first look when reading a circuit schematic is look at the main loop. And then look at the control loop, the control loop requirements are from top to bottom or from left to right. The circuit diagram mainly consists of four parts: component symbol, connection, node and comment/note.

1. Component Symbols

These represent the actual components in the circuit. Their shapes may not resemble the actual components and can even be completely different. However, they generally indicate the characteristics of the components, and the number of pins matches the actual components.

2. Connections

These represent the wires in the actual circuit. While they appear as lines in the schematic, they are often not lines but various shapes of copper foil blocks on commonly used printed circuit boards (PCBs). For example, many connections in a radio schematic may not be line-shaped on the PCB but rather in specific shapes of copper film.

3. Nodes

These indicate the connections between multiple component pins or wires. All component pins and wires connected to a node are conductive, regardless of the number.

4. Comment/note

These are very important in a schematic. All the text in the schematic can be classified as notes. A close look at the schematics reveals annotations everywhere, used to indicate component models, names, and other information.

Best Technology offer top-quality advanced PCB boards, from prototypes to mass production. Our range includes FR4 PCBs of any Tg, FPC, ceramic PCBs, aluminum PCBs, Teflon PCBs, and copper-base PCBs. Every product and service is traceable and verified with ISO, IATF, RoHS, UL, and REACH certifications. Enjoy free samples for bulk orders, complimentary functional testing, and fast delivery.

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What is Tda7294 amplifier board &tda7294 datasheet

August 7th, 2024

TDA7294 is a class AB monolithic audio amplifier integrated circuit launched by SGS-THOMSON Microelectronics in the 1990s. It swept away the raw, cold and hard sound of previous linear integrated amplifiers and thick film integrated amplifiers, and is widely used in HiFi fields, such as home theaters, active speakers, high-performance TVs and other fields.

TDA7294

The chip adopts a 15-pin dual-row asymmetric plug-in package, the differential input stage is composed of bipolar transistors, and the driver stage and power output stage use DMOS field-effect transistor semiconductor technology. This hybrid semiconductor manufacturing process allows TDA7294 to take into account the advantages of bipolar signal processing circuits and MOS power tubes, and the playback sound is very friendly (it is praised by audiophiles as a “tube-flavored amplifier”); the built-in silent standby function, short-circuit current and overheating protection functions make its performance more perfect. It can be used in HiFi home audio, active audio, high-performance TVs and other fields.

Tda7294 amplifier board

tda7294 amplifier board PCBA

This circuit is an official standard circuit, stable and reliable.
The filter uses a large electrolytic capacitor with a withstand voltage of 50V and a capacity of 2200uf.
Power supply voltage: dual 12-36V ring transformer, dual 32V ring transformer is recommended
Output power: 85W*1 undistorted rated power, peak power 100W
Can easily drive speakers above 100W, speaker impedance: 4-8 ohms
PCB size: 50*50mm

Basic parameters:
Power supply: dual 18-28V AC
Power: 2X80W+160W subwoofer
Circuit board size: 218x98MM
Potentiometer function: low frequency frequency adjustment, subwoofer volume. Left and right channel volume, treble, bass.

Adopting the new laser dark word TDA7294
The power filter uses 6 63V3300UF capacitors, and the rectifier uses a 25A imported rectifier flat bridge.
PCB uses 1.6mm thick double-sided board, 2.0 ounces copper thickness, and full tin spraying process to ensure good passing performance of large and small currents.
Fever component assembly, the subwoofer part consists of two new TDA7294 BTL output,
The low-pass filter is designed according to the frequency adjustable design of home theater style (50-150HZ), with strong power!
The left and right channels are served by two TDA7294 respectively, and the input coupling capacitor uses the German imported WIMA 2.2UF coupling capacitor, which makes the sound sweeter!
The signal-to-noise ratio of the board is also very high, and even if you put your ear close to the speaker, you can’t hear the AC noise! It is the best choice for upgrading 2.1 amplifiers!

TDA7294 datasheet

TDA7294 Main Features

Wide supply voltage range: ±10V ~±40V
High output power: 70W (up to 100W)
Standby and mute functions
Noiseless ON/OFF switch
Low noise and low distortion
Short circuit protection and overheat protection

TDA7294

Pin function
Pin 1 is the standby terminal;
Pin 2 is the inverting input terminal;
Pin 3 is the positive input terminal;
Pin 4 is grounded;
Pins 5, 11, and 12 are empty pins;
Pin 6 is the bootstrap terminal;
Pin 7 is +Vs (signal processing part);
Pin 8 is -Vs (signal processing part);
Pin 9 is the standby pin;
Pin 10 is the mute pin;
Pin 13 is +Vs (final stage);
Pin 14 is the output terminal;
Pin 15 is -Vs (final stage)

DIY Production

1) The first step is to get the PCB. Here you can make the PCB yourself by DIY ironing method. Since the PCB is easy to make, the PCB design is kept single layer only, or you can get ready-made quality PCB from best.or custom tda7294 amplifier board.
2) After the PCB is completed, carefully mount all small components like jumpers, resistors, diodes, etc. to the PCB and trim their terminals, then solder them to the PCB first, because there are many components on this board, so it is better to solder them one by one
3) After installing the small components, install the large components like capacitors, fuse holders, rectifiers to the PCB and solder them. (Don’t install the power filter capacitor, 22000uF capacitor for now. Completed in the following steps)
4) After that, it’s time to mount all 7 ICs to the PCB and solder them.
5) Now properly mount the heat sink on the IC using insulating MICA and insulating plastic shoulder washers. Remember to use good quality thermal paste between the heat sink and IC.
6) After mounting the IC on the heat sink. Check the continuity between the heat sink and the IC back plate using a multimeter. There should not be any continuity between them. Please note the heat sink isolation
7) Now mount the cooling fan to the PCB using cable ties or any other suitable method.
The board assembly is now complete. Clean the track side of the board using IPA (Isopropyl Alcohol) or cleaning flux and then power the board using a 20-0-20 VAC transformer or a 24-0-24 VAC transformer.

Which one has better sound quality, TDA7294 or LM3886? Voltage AC 28v

LM3886 has better bass because its maximum current can reach 10A, which means it can drive a 2-ohm box without any problems. From the parameters alone, LM3886 is worse than 7294. And it is true in practice, especially for bass. If the transformer is OK, it feels very powerful. 7294 is not as good as 3886 in bass. The current is large when it comes to bass. 7294 itself has overcurrent protection. When the current reaches a certain level, it starts to limit the output current. However, 7294 is better in treble.

Tags: PCB, PCBA, SMT
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How to Check PCB with a Multimeter?

August 5th, 2024

Common PCB failures are mainly concentrated on components such as capacitors, resistors, inductors, diodes, transistors, MOSFETs, integrated chips (IC), and crystals. Some obvious damages can be visually detected, while others require the use of tools. Today, let’s learn how to troubleshoot PCB faults using a multimeter.

How Will You Diagnose a Faulty PCB By Visually?

For some printed circuit boards, we can check by our naked eyes. Here are some common ways to follow:

1. Check the condition of components

When you get a faulty PCB, first observe if there are any obvious component damages, such as burnt or swollen electrolytic capacitors, burnt resistors, and damaged power devices.

2. Inspect the soldering of the PCB

Check if the printed circuit board (PCB) is deformed or warped; if there are any loose or poorly soldered joints; if the copper cladding on the PCB is lifted, burnt, or blackened.

3. Examine the component plug-ins

Ensure the correct orientation of integrated circuits, diodes, and the PCB power transformer.

How to Check PCB with a Multimeter?

Before you start testing your PCB, ensure you have the right tools and environment. Here’s a checklist to get you started:

1. Safety First: Wear anti-static gloves and ensure you are working on an anti-static mat to prevent damage to the PCB.

2. Multimeter Selection: Choose a multimeter with the ability to measure voltage, resistance, and continuity. A digital multimeter is preferred for accuracy.

3. Visual Inspection: Examine the PCB for visible signs of damage such as burnt components, broken traces, or solder bridges.

4. Power Off the Board: Always test the PCB with the power off to avoid any electrical hazards and damage to the multimeter.

How Do You Test Individual Components on a PCB?

Testing individual components like resistors, capacitors, and diodes can pinpoint the exact failure. Here’s a general approach:

Diode
Transistor
MOSFET
Electrolytic Capacitors

How to Test Diodes?

1. Set the MF47-type multimeter to measure resistance.

2. Place the red and black probes on the two ends of the diode and read the value.

3. Swap the probes and measure again.

4. Judge based on the two measurements: the forward resistance of small power germanium diodes is 300-500Ω, silicon diodes are about 1kΩ or larger. The reverse resistance of germanium diodes is tens of kilo-ohms, and silicon diodes are above 500kΩ (values are much smaller for high-power diodes). A good diode has low forward resistance and high reverse resistance, and the larger the difference, the better.

5. If both forward and reverse resistances are very low, the diode is short-circuited; if both are very high or infinite, the diode is open-circuited and needs to be discarded.

How to Test Transistors?

1. Set the digital multimeter to the diode mode.

2. Measure the PN junction with the probes. If it conducts forward, the displayed value is the forward voltage drop of the PN junction.

3. Determine the collector and emitter: measure the forward voltage drop of the two PN junctions, the larger drop is the emitter (e), and the smaller drop is the collector (c). If the red probe is connected to the common terminal, the transistor is NPN type, and the common terminal is the base (b); if the black probe is connected to the common terminal, the transistor is PNP type, and the common terminal is the base (b).

4. For in-circuit testing, measure the forward and reverse resistance of the PN junction to determine if the transistor is damaged. If the branch resistance is larger than the forward resistance of the PN junction, there should be a clear difference between the forward and reverse resistances, otherwise, the PN junction is damaged.

The Way to Test MOSFETs?

1. Connect the black probe to the drain (D) and the red probe to the source (S), the resistance should be 500-600.

2. Without moving the black probe, touch the gate (G) with the red probe, then measure the source (S) again; it should conduct.

3. Connect the red probe to the drain (D), touch the gate (G) with the black probe, then measure the source (S); the resistance should be the same as the first measurement, indicating the MOSFET is working normally.

How to Test Electrolytic Capacitors?

1. Select the appropriate range on the MF47-type multimeter based on the capacitor’s capacity. Use R×1K range for capacitors below 47μF, and R×100 range for those above 47μF.

2. Connect the red probe to the negative lead and the black probe to the positive lead of the capacitor.

3. On initial contact, the multimeter needle will deflect right and then gradually return to the left until it stops at a certain position (close to infinity). This value is the capacitor’s forward leakage resistance; the larger the value, the better the capacitor’s performance.

4. Swap the probes and repeat the process. The measured value will be the reverse leakage resistance, slightly smaller than the forward leakage resistance.

5. If no charging phenomenon occurs (the needle doesn’t move), the capacitor is either open or short-circuited internally. If the resistance is very small or zero, the capacitor is leaky or has broken down and cannot be used.

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