It’s essential to ensure that solder joints are made correctly in any electronics construction. Poor and dry soldering cause equipment not to work once. Or there is a possibility that the solder joint could fail. In this blog, we will introduce why dry soldering occurs and how to solve it.
What is Meant by Dry Soldering?
Dry soldering refers to a poor solder joint that lacks proper electrical connectivity on a PCB assembly product. This issue occurs when the solder does not properly melt and bond to the components, leading to weak connections. These joints are often brittle and prone to failure, which can result in intermittent or complete loss of electrical connectivity.
Why Dry Solder Joint Causes?
Dry solder joints occur due to several reasons, each impacting the quality of the solder connection. First of all, the solder paste reflow process is only a small area, which is easier to harden than the solder paste in the solder paste can. At this time, the solder paste will not melt, and the flux cannot cover the solder joint, resulting in poor welding of the solder joint. Meanwhile, the solder paste is easier to heat transfer, and the high temperature actually makes the solder paste not easy to melt, so we can slightly adjust the reflow welding temperature curve to solve the problem, or welding in a nitrogen environment is basically a good way to solve this problem.
Secondly, the solder paste does not melt because its own composition contains a very volatile flux, which is also the reason why the solder paste is easy to harden. Among them, the flux with the largest content of solder paste is rosin, rosin contains a lot of rosin acid, rosin acid is easy to lose activity at too high temperature. Therefore, the temperature of the welding process should be controlled to ensure that the temperature is about 200 ° C, which is not suitable for too high or too low. At the same time, the quality of thixotropic agent will also lead to the solder paste is easy to dry, the quality of thixotropic agent is not good will affect the viscosity of the solder paste, the viscosity of the solder paste is easy to dry. Therefore, the choice of high-quality solder paste can fundamentally solve the problem that the solder paste is easy to harden.
In addition, the use of solder paste scene, humidity, temperature and other external factors will also affect the solder paste in the use of hard non-melting phenomenon. So these external factors should be paid attention to. I hope these solutions can solve your problems.
How Do You Fix Dry Solder?
Solder paste is one of the very important materials in the electronics industry, and it has an important impact on the production quality of the entire component. Here are some tips that can help to fix the dry solder paste.
1.Add flux
Usually, if the solder paste is too dry, you can try to add some water to the right amount of flux, stir well and add it to the solder paste. This can play a certain role in alleviating drying and improve the fluidity of the solder paste.
2. Take some measurements during management
a. Keep the ambient temperature moderate during storage;
b. Stir well before use;
c. Cover the solder paste in time after welding to avoid exposure to the air.
3. Replace it with new one
If the solder paste becomes too dry, adding flux is difficult to restore its original properties, it is recommended to replace the solder paste to avoid affecting the quality of the components.
Therefore, we need to regularly maintain and manage the solder paste to ensure that its quality meets the standard requirements.
What Does a Dry Solder Look Like?
Recognizing a dry solder joint is crucial for proper diagnosis and repair. Unlike a good solder joint, which is shiny and smooth, a dry joint looks matte and rough. The joint might have visible cracks or look brittle. It might not be fully bonded to the component lead or the PCB pad. Identifying these visual cues can help in quickly addressing the issue.
How Do You Prevent Dry Solder?
Preventing dry solder joints is key to maintaining the reliability of your electronic projects. You can try to use these tips to prevent your solder paste become dry.
Proper heating
Clean surfaces
Use quality solder
Steady hand
Maintain equipment
Fast usage and storage
If you want to know more about solutions of dry solder paste, you can read our another post, How to Solve Dry Solder Paste.
How to Tell If Solder is Bad?
Bad solder can lead to dry joints and other issues. So, how can we identify if my solder paste is bad? May you can follow these points. If everything matches up, there’s no doubt that your solder paste is broken.
Appearance of solder joints
Bad solder joints often appear dull or matte instead of shiny and smooth. They may also show cracks or a brittle texture, indicating poor bonding or excessive heating. These visual signs suggest that the solder did not properly melt or flow.
Solder flow and coverage
If the solder does not adequately cover the component leads or PCB pads, or if it spreads unevenly, it is likely bad. Proper soldering should result in a well-formed, consistent fillet around the leads, ensuring reliable electrical connections.
Difficulty in melting
Solder that requires unusually high temperatures or takes a long time to melt may be old or contaminated. Proper solder should melt easily at the recommended temperature and flow smoothly to create a solid joint.
Contamination indicators
Oxidized or tarnished solder indicates contamination and can affect its performance. Excessive residue or debris also points to poor quality, affecting how well the solder adheres and flows.
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A zero PCB, also known as a prototype PCB or breadboard, is a type of circuit board used for building and testing prototypes. Unlike traditional PCBs, which have pre-defined paths for electric connections, zero PCBs offer a grid of holes. This grid allows for custom circuit designs using wires and components. Engineers and hobbyists use zero PCBs to experiment and develop new electronic circuits without committing to a specific design.
What is a zero PCB?
Zero PCBs are particularly helpful in testing circuit designs for any shortcomings. They provide a cost-efficient way to evaluate the circuitry before committing to a final solution. The term ‘zero’ in this context signifies a fundamental distinction. It implies that there are no predefined connections, layouts, or functions on the PCB.
Generally, there is no solder mask and silkscreen on the zero board. The primary purpose of a zero PCB is to offer a blank canvas for users to create and test custom circuits. As a result, they are intentionally kept simple in structure to allow for maximum customization. Users are free to design and solder their circuits and components directly onto the board without the constraints of a predefined layout or solder mask.
What is the use of a zero board?
Zero boards serve a variety of purposes in the electronics industry. They are particularly useful for prototyping and testing new circuit designs. Here are some common uses:
Prototyping
Educational purposes
Quick fixes
Small-scale production
Zero PCBs have a layer of copper traces or pads on the substrate. These copper elements provide the conductive pathways for soldering electronic components and forming connections. However, the copper traces on zero PCBs are usually unconnected, meaning there is no predefined circuit layout. You can build a circuit on them by inserting components into the holes and then connecting them with wires.
What is the cost of a zero PCB board?
The cost of zero PCB boards varies based on size, material, and supplier. Generally, they are quite cost-effective, so that both professional engineers and hobbyists can afford it. Prices can range from a few cents for small boards to several dollars for larger or more specialized versions. Bulk purchasing often reduces the cost per unit. Additionally, different materials, such as fiberglass or phenolic, can affect the price.
What size is a zero PCB board?
Zero PCB boards come in various sizes to accommodate different project needs. Common sizes include:
Small: Typically around 5×7 cm, ideal for simple projects.
Medium: Sizes like 10×15 cm offer more space for complex circuits.
Large: Boards as large as 30×30 cm are available for extensive projects.
The grid pattern usually remains consistent, with a standard pitch of 2.54 mm (0.1 inches) between holes, regardless of the board’s overall size.
What is a bare board?
A bare board, also known as a blank PCB, is a printed circuit board that has not yet been populated with any electronic components. It is essentially the foundation of a PCB, consisting only of the substrate material (such as fiberglass) and the copper traces that form the circuit pathways. A bare board typically include base core, prepreg and copper trace layer.
Features of a bare board
Substrate material
The base material of a bare board is usually fiberglass, FR4, or other insulating materials that provide mechanical support.
Copper traces
These are the conductive pathways etched onto the substrate. They form the circuit’s electrical connections but are not yet connected to any components.
Pads and holes
Bare boards include pads (flat areas of copper for soldering components) and drilled holes for through-hole components.
Pre-defined layout
The copper traces and pads are arranged according to a specific design, determined during the PCB design process.
No components
A bare board does not have any electronic components soldered onto it yet. It is essentially a “blank slate” ready to be populated.
Coated solder mask and silkscreen
Most bare boards have a solder mask, a protective layer that prevents solder from bridging between conductive areas, and a silkscreen, which provides component labels and other information.
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In our daily life, the electronics has been gradually infiltrated our lives. Between them, the PCB board plays an important role in it, and we must say, PCB is the foundational element of electronics. From the simplest gadgets to the most complex machinery, PCBs play a crucial role.
What is a PCB Board?
A printed circuit board (PCB) is an electronic that uses metal conductors to create electrical connections between components. Generally, a PCB is a flat, laminated composite made of non-conductive substrate materials with conductive pathways etched or printed onto it. These pathways, also known as traces, enable the electronic components mounted on the board to communicate with each other.
PCBs are designed to support and electrically connect various components such as resistors, capacitors, diodes, and integrated circuits. The intricate network of copper tracks forms circuits that dictate the device’s functionality. PCBs can range from simple single-sided boards used in basic electronics to complex multi-layered structures found in advanced applications.
Common PCB Structure
A PCB’s structure is composed of several key layers, each serving a distinct purpose. Here is a detailed breakdown of these layers:
Substrate (Base Material)
The substrate, usually made of fiberglass (FR4), provides the board with its rigidity and thickness. It is the foundational layer upon which all other materials are built.
Copper Layer
This conductive layer is typically made of copper foil. For single-sided PCBs, the copper layer is only on one side of the substrate, whereas double-sided and multi-layer PCBs have copper layers on both sides or between multiple layers of substrate.
Solder Mask
The solder mask is a protective layer applied over the copper traces to prevent oxidation and accidental short-circuiting. It insulates the copper traces and leaves the component pads exposed for soldering. The green color commonly associated with PCBs comes from this layer, though it can also be found in other colors like red, blue, black, and white.
Silkscreen
The silkscreen layer is used to add labels, symbols, logos, and other markings to the PCB. This layer helps in identifying component locations and orientations during assembly and troubleshooting.
Components and Connectors (PCBA)
Components such as resistors, capacitors, diodes, and integrated circuits are soldered onto the PCB. Connectors allow the PCB to interface with other boards, power supplies, and external devices.
How Many Types of PCB?
Single-Sided PCBs
These are the simplest types of PCBs, with copper on only one side of the board. You’ll find them in basic, low-cost electronics like calculators, radios, and power supplies. They’re easy to design and manufacture, which keeps costs down and makes them great for straightforward applications.
Double-Sided PCBs
These boards have copper layers on both sides, allowing for more complex circuits. They’re common in more sophisticated electronics like amplifiers, power monitoring systems, and HVAC systems. With increased circuit density and flexible design options, they can handle more complex tasks.
Multi-Layer PCBs
When you need to pack in a lot of circuits, multi-layer PCBs are the way to go. They consist of three or more layers of copper, separated by insulating layers. You’ll see these in high-tech devices like computers, servers, medical equipment, and aerospace electronics. They offer high circuit density, reduced size and weight, and better signal integrity.
Rigid PCBs
Made from solid, inflexible materials like fiberglass, rigid PCBs keep their shape and provide strong support for components. They’re durable and used in everything from simple toys to complex industrial equipment.
Flexible PCBs
These are made from flexible plastic materials like polyimide, allowing them to bend and flex. Perfect for wearable electronics, flexible displays, and compact devices where space is tight. They’re lightweight, can fit into small, irregular spaces, and can handle being bent repeatedly.
Rigid-Flex PCBs
Combining the best of both rigid and flexible PCBs, these are great for devices that need both stability and flexibility, like smartphones, cameras, and medical devices. They save space, reduce the need for connectors and interconnections, and improve reliability.
High-Frequency PCBs
Designed to operate at frequencies above 1 GHz, these are used in communication systems, microwave technology, and high-speed devices. They provide low signal loss and high performance, making them crucial for advanced communication technologies.
Ceramic PCBs
Using ceramic as the substrate material, these PCBs offer excellent thermal conductivity and stability. They’re perfect for high-power applications and environments with extreme temperatures, like LED lighting, power electronics, and aerospace systems. Ceramic PCBs ensure reliable performance in harsh conditions.
Metal Core PCBs
Featuring a metal core, usually aluminum or copper, these PCBs improve heat dissipation. They’re used in high-power applications where efficient thermal management is crucial, such as LED lighting, power supplies, and automotive electronics.
Special PCBs
Bus Bar PCBs
These integrate bus bars for high-current applications, ensuring efficient power distribution and minimal voltage drop. They’re used in heavy-duty power supplies, electric vehicles, and industrial machinery. Bus bar PCBs provide robust and reliable connections for high-power systems.
Heavy Copper PCBs
With thicker copper layers, typically 3 ounces per square foot or more, these PCBs can handle higher currents and enhance thermal management. They’re used in power distribution, automotive, and industrial applications where durability and performance are critical. Heavy copper PCBs ensure reliable operation under high-stress conditions.
HDI (High-Density Interconnect) PCBs
These feature finer lines and spaces, smaller vias, and higher connection pad density. They’re used in advanced electronics like smartphones, tablets, and medical devices where space and performance are paramount. HDI PCBs enable miniaturization and improved electrical performance.
Extra Thin PCBs
Designed with minimal thickness, these PCBs are perfect for fitting into compact and lightweight devices. You’ll find them in flexible displays, wearables, and miniaturized electronic gadgets. Extra thin PCBs allow for innovative design solutions and space-saving configurations.
RF (Radio Frequency) PCBs
Optimized for high-frequency signals, these are used in communication devices, antennas, and microwave applications. They’re designed to minimize signal loss and interference, ensuring optimal performance in wireless communication systems.
High Tg PCBs
These have a high glass transition temperature, making them suitable for high-temperature environments. Used in automotive, aerospace, and industrial applications, high Tg PCBs maintain structural integrity and performance at elevated temperatures.
Impedance Control PCBs
These are designed to maintain consistent impedance for high-speed signal transmission. They’re used in communication devices, high-speed digital circuits, and advanced computing systems. Impedance control PCBs ensure signal integrity and reduce signal loss and reflection.
Why Are PCB Boards So Expensive?
Material Quality
High-grade materials like FR4 (fiberglass), ceramics, and high-quality copper foil are used to ensure durability and performance. These materials are essential for withstanding environmental stress and ensuring reliable operation, but they are expensive. For example, ceramic substrates can cost up to 10 times more than standard FR4 materials due to their superior thermal conductivity and electrical properties.
Complexity of Design
Multi-layer PCBs and advanced designs such as HDI (High-Density Interconnect) boards require complex manufacturing processes. The process involves precise alignment of layers and sophisticated techniques like laser drilling for micro-vias. The added complexity increases the production costs significantly. For instance, a standard 4-layer PCB might cost $50 per square meter, while a 12-layer HDI PCB could cost over $200 per square meter.
Precision and Technology
Manufacturing high-precision PCBs involves advanced machinery for etching, drilling, and plating. This machinery requires significant investment, and the skilled labor needed to operate it adds to the cost. The precision required in the production process ensures that the PCBs meet exacting standards, crucial for high-performance applications. A single advanced PCB drilling machine can cost upwards of $500,000.
Volume of Production
Smaller production runs generally have higher costs per unit because the setup and tooling expenses are spread over fewer units. For example, a low-volume production run of 10 PCBs might cost $100 per board, whereas a high-volume run of 10,000 boards might reduce the cost to $10 per board due to economies of scale.
Testing and Quality Assurance
Rigorous testing, including electrical, thermal, and functional tests, ensures that the PCBs meet strict performance standards. This testing process is vital to ensure reliability, especially in critical applications like medical devices and aerospace. Quality assurance processes can add 20-30% to the overall production cost, but they are essential for maintaining high standards.
What is the Difference Between PCBA and PCB Board?
The terms PCB and PCBA are often used interchangeably, but they refer to different stages of the board’s life cycle. The PCB is the bare board itself, with no electronic components attached. It consists of a non-conductive substrate, copper traces, solder mask, and silkscreen. A PCB serves as the foundation for assembling electronic components.
On the other hand, a PCBA (Printed Circuit Board Assembly) is a PCB that has undergone the assembly process, where all necessary electronic components like resistors, capacitors, diodes, and integrated circuits are soldered onto the board. Essentially, a PCBA is a functional circuit board ready for use in electronic devices. The transition from a PCB to a PCBA involves component placement, soldering, and quality testing, transforming the bare board into an operational assembly. Below is a typical PCBA product for your reference.
What is PCB Board Common Use?
PCB boards are existing in everywhere what we live, for example, the global smartphone market, which relies heavily on PCBs, was valued at approximately $520 billion in 2020. Here are some common applications that PCB used in:
Automotive Industry
In the automotive sector, PCBs are used in engine control units, infotainment systems, and advanced driver-assistance systems (ADAS). These applications enhance vehicle performance, safety, and connectivity.
Medical Devices
PCBs are integral to medical devices such as diagnostic equipment, patient monitoring systems, and implantable devices. They ensure precise and reliable operation, which is critical for patient safety and effective treatment.
Industrial Applications
PCBs are used in control systems, machinery, and power distribution units in industrial settings. They provide robust and durable solutions capable of withstanding harsh conditions and continuous operation.
Telecommunications
In telecommunications, PCBs are essential in routers, switches, and communication devices, ensuring efficient and reliable data transmission. As the demand for faster and more reliable communication networks grows, so does the need for high-quality PCBs.
Why Are Circuit Boards Green?
The characteristic green color of most PCBs comes from the solder mask, a protective layer applied over the copper traces to prevent oxidation, short-circuiting, and to protect the board during soldering.
The green color is traditional, largely due to historical reasons and practical benefits. Green solder mask provides a good contrast against the white silkscreen and the shiny copper traces, making it easier for technicians to inspect and identify components during assembly and troubleshooting. Additionally, green solder mask was one of the first colors to be developed and standardized in the industry, leading to its widespread adoption. However, PCBs are not limited to green; they can also be found in other colors such as red, blue, black, and white, depending on the specific requirements and aesthetic preferences of the project. The choice of solder mask color does not affect the performance of the PCB, but green remains popular due to its well-established manufacturing process and visual advantages.
How to Get Started with Best Technology?
Here at Best Technology, we are experienced in designing all types of PCBs, including standard rigid PCBs, special PCBs, and irregular PCBs. We can design and develop PCBs according to customer specification and offer suggestions on the right materials for your project.
We provide the full series of PCB manufacturing, from the initial PCB design, PCB layout, to custom PCB fabricate, PCB assembly, box building and so forth. By the way, we have our own factory in Vietnam, that means we can ship out the PCBs directly from Vietnam.
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If you are familiar with SMT or PCB assembly process, you may know BOM file. It is an important element in the SMT process. Creating BOM is a crucial step in the manufacturing process, especially for PCBs. A BOM serves as a comprehensive list of all the parts, components, and materials needed to build your product. It ensures that everyone involved in the production process is on the same page, reducing the risk of errors and delays. Today, Best Technology would like to introduce BOM and giving you a guide to create a BOM file step by step.
What is a Bill of Materials (BOM)?
A Bill of Materials (BOM) is a detailed list of all the parts, components, and materials needed to manufacture a product. In PCB manufacturing, a BOM outlines every item required to assemble a PCB, including quantities, part numbers, and descriptions. It serves as a guide to ensure that the manufacturing process runs smoothly and that no crucial components are missing.
Types of Bill of Materials
There are several types of BOMs used in different stages of production. Each type serves a specific purpose and provides unique details to streamline processes and ensure accuracy. Here are the primary types of BOMs:
Engineering BOM
This type of BOM is creating during the design phase. It lists all the parts and components designed by the engineering team, including specifications and relationships as intended in the final product. And of course, it mainly used by design engineers to communicate the product structure and details to manufacturing teams.
Manufacturing BOM (Formal)
It is a formal BOM files that used in the assembly phase. Different with engineering BOM, it includes additional details necessary for manufacturing, such as packaging, handling instructions and assembly details. And some special instructions.
Sales BOM
Sales BOM is used by sales teams and includes information relevant to the sales process, such as pricing and availability. It helps in providing accurate quotes, managing customer expectations, and handling sales orders efficiently.
What Should Include in an Effective Bill of Materials?
An effective BOM should be detailed, accurate, and easy to understand. It should include all the details of components and indicated revisions. As a 18 years expertise in PCBA production, we summarized the key elements that should be included in the BOM.
Component details
It should include all the components and their detailed information, such as names, part numbers (PN), and descriptions for each part.
Quantity (QTY)
The exact quantity of each component required for the product. Accurate quantities can prevent shortages and overstocking.
Foot print
It is the package of each component, helping to ensure the correction of part.
Reference Designators
Unique identifiers that match each component to its specific location on the product layout. These are essential for assembly and troubleshooting.
Manufacturer Information
Manufacturer information, including the manufacturer name of components and manufacturer part number. It helps to ensure correct parts are sourced. And convenient for alternative part sourcing if it is shortage.
Supplier information (Optional)
It means the name of the supplier or distributor. The part number used by the supplier, which may differ from the manufacturer’s part number.
Assembly instructions
Any special notes for assembly such as DNF remark, and version control to track revisions should also be included. Additionally, cost information helps in budgeting, and lifecycle status information helps plan for component availability and avoid discontinued parts.
How to Make a PCB Bill of Materials (BOM)?
Creating a PCB BOM is a systematic process that involves compiling all the necessary information about each component required for the assembly of the PCB. Here’s a detailed guide on how to create a PCB BOM:
Open a Blank Spreadsheet
Use software like Microsoft Excel or Google Sheets to start with a blank spreadsheet. They are common to use, offering flexibility and ease of use for creating and managing BOMs.
Define Columns
Set up your spreadsheet with appropriate column headers. Common headers include:
Part Number
Component Name
Quantity
Reference Designator
Manufacturer
Manufacturer Part Number
Supplier
Supplier Part Number
Description
Package Type
Cost
Notes
Input Data
Enter the required details for each component under the appropriate headers. Please be make sure that all information is accurate and complete. This may involve referencing design files, datasheets, and supplier catalogs. If it is incorrect, then it needs a lot of time to find out and revise the errors, resulting in schedule delay.
Use Formulas
Utilize Excel formulas to automate calculations, such as summing total quantities or calculating costs. This helps in reducing manual errors and saves time.
Format for Clarity
Use cell formatting options to highlight important information and ensure the spreadsheet is easy to read. For example, you can use bold text for column headers, color coding for different component types, and borders to separate sections.
Include Version Control
Add a version control section to your BOM to track revisions and updates. This can be a simple row at the top or bottom of the spreadsheet, indicating the version number, date of revision, and a brief description of changes.
(BOM file reference)
Save and Update
Save your BOM and update it regularly to reflect any changes in the design or component availability. Regular updates ensure that the BOM remains accurate and up-to-date, preventing issues during production.
Review and Verify
Have multiple team members review the BOM for accuracy. Cross-check all component details, quantities, and part numbers against the design files. Verification helps catch errors early and ensures the BOM is reliable.
Communicate with Suppliers:
Maintain open communication with suppliers to confirm component details and availability. This ensures that you can source the correct parts and avoid delays in the production process.
How Can I Optimize My BOM for PCB Assembly?
Sometimes, a simple BOM is not good to process PCB assembly process, and manufacturers may need to spend a lot of time to optimize it, make into convenient for manufacturing. If you are a layman, here are some steps to help you in optimizing your BOM file.
First, it’s a good idea to standardize components where possible. Using standard parts that are readily available from multiple suppliers can simplify procurement and reduce costs. This approach minimizes the risk of shortages and ensures you can get parts quickly and affordably. Also, make sure all entries in your BOM are clear and concise to avoid confusion during assembly. Double-checking part numbers and quantities against design files is crucial to prevent errors that could lead to rework or delays.
Building strong relationships with your suppliers is another key factor. Good communication with suppliers helps ensure reliable component availability and keeps you informed about any changes in lead times or part availability. Regularly updating your BOM to reflect any design changes or component availability issues is essential. Keeping your BOM current and accurate prevents last-minute surprises during assembly.
What Common Mistakes Should I Avoid When Creating a PCB BOM?
Avoiding common mistakes in BOM creation can save time and reduce errors. Here are some pitfalls to watch out for:
Incomplete information – ensure all necessary details are included for each component.
Incorrect quantities – double-check quantities to avoid shortages or excess inventory.
Outdated data – keep the BOM updated with the latest design changes and component information.
Ambiguous descriptions – provide clear and precise descriptions to prevent confusion.
Lack of version information – implement version control to track changes and ensure the correct BOM version is used.
Creating an effective and accurate PCB BOM is essential for smooth manufacturing and assembly. By following best practices and using the right tools, you can ensure your BOM is comprehensive, clear, and up-to-date, ultimately leading to a successful PCB production process.
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In the world of printed circuit boards (PCBs), understanding material properties is crucial. One such property is Tg, or glass transition temperature. For FR4 PCBs, knowing what Tg means can significantly impact design and performance. In this blog, we’ll explore what Tg is, how it’s measured, its importance, and other related questions.
What Does Tg Mean in PCB Manufacturing?
Tg stands for glass transition temperature. It refers to the temperature at which a polymer material, such as the resin in a PCB substrate, transitions from a hard, glassy state to a softer, rubbery state.
For the circuit board, the Tg value reflects the highest temperature it can withstand. When the temperature exceeds Tg values, the molecular structure of the circuit board material will be changed, lead to changes in its physical properties. Such as mechanical strength, size stability, adhesive, water imbibition, thermal expansion, etc. Therefore, the level of TG value of the PCB directly affects the stability and high temperature resistance of the circuit board.
In the high temperature environment, if the TG value of the circuit board is too low, it is easy to cause PCB deformation, fracture, cracking and other problems, affecting the reliability and life of the printed circuit board. If the TG value of the circuit board is too high, the PCB is easy to become hard and brittle, affecting the processability and flexibility of the circuit board.
How is Tg Measured in FR4 Materials?
Accurate measurement of Tg is crucial for ensuring the performance and reliability of FR4 PCBs. Knowing the exact Tg helps in selecting the appropriate material for specific applications, particularly those involving high temperatures and thermal cycling. Using materials with a Tg well above the operating temperature ensures the PCB will maintain its mechanical and electrical properties under expected conditions.
The primary method for measuring Tg in FR4 materials is by differential scanning calorimetry (DSC). It involves heating a small sample of the material at a controlled rate, typically between 10°C to 20°C/min. As the sample heats, the DSC measures the heat flow into the material and records it as a thermogram. The Tg is identified as the temperature where there is a noticeable change in heat capacity, appearing as a step or inflection point on the thermogram. DSC is widely used because it provides precise and reliable Tg measurements.
Additionally, Dynamic Mechanical Analysis (DMA) and Thermomechanical Analysis (TMA) also can be used to measure the Tg value.
Why is Glass Transition Temperature Critical in PCBs?
Glass transition temperature is critical because it affects the thermal and mechanical properties of the PCB. If a PCB operates near or above its Tg, it can experience issues like delamination, warping, and electrical failure. Here are some benefits of Tg.
Thermal stability
One of the main reasons is its role in determining thermal stability. During operation, PCBs are subjected to varying temperatures due to power dissipation from electronic components and environmental conditions. Make sure the Tg of the PCB material is well above the maximum operating temperature, it helps maintain mechanical stability and reliable performance under thermal stress.
Mechanical Strength
The Tg value also affects the mechanical strength and durability of the PCB. Below the Tg, the material is rigid and can withstand mechanical stress without significant deformation. This rigidity is essential for maintaining the structural integrity of the PCB, especially during assembly processes like soldering, where the board is subjected to mechanical and thermal stresses.
Thermal Management
Thermal management is very important to electronics, especially for those miniaturized electronic devices. If the PCB itself has good thermal management, then designers no need to install heatsink or coolers. Materials with higher Tg values exhibit lower coefficients of thermal expansion (CTE), meaning less expansion and contraction with temperature changes.
Application-specific requirements
Different applications have varying thermal and mechanical requirements. High-performance computing, automotive, aerospace, and industrial electronics often operate in environments with high temperatures and thermal cycling. For these applications, using PCB materials with appropriate Tg values is crucial.
What is the Typical Tg Value for Standard FR4 PCBs?
Standard FR4 materials generally have Tg values in the range of 130°C to 140°C. For high-performance applications, materials with higher Tg values are necessary. The table below lists some common high Tg materials used in PCB manufacturing, along with their Tg values and characteristics.
Material
Tg Value (°C)
Characteristics
Applications
ISOLA IS410
180
Excellent thermal and mechanical properties
High-reliability applications
Nanya NP-175
175
High thermal stability, good mechanical strength
Automotive, industrial electronics
Shengyi S1000H
170
Cost-effective, widely used
Consumer electronics, industrial applications
Ventec VT-47
170
High Tg and low CTE
High-density interconnect (HDI) PCBs
Rogers 4350B
280
Extremely high Tg, excellent thermal stability
RF and microwave applications
(Common used high Tg materials)
Can You Explain the Difference Between Tg and Td in PCBs?
Tg and Td (decomposition temperature) are two different thermal properties. Unlike the reversible physical change associated with Tg, decomposition is an irreversible chemical process. At Td, the polymer chains in the material break down, leading to a loss of structural integrity and release of volatile compounds. Key points about Td include:
1. Chemical Stability
Td represents the upper thermal limit of a material’s chemical stability. Exceeding Td results in the breakdown of the polymer structure, rendering the material unsuitable for further use.
2. Material Selection
Knowing the Td helps in selecting materials for high-temperature applications. A material’s Td should be well above the maximum operating temperature to prevent degradation.
3. Safety and Reliability
Operating a PCB above its Td can result in catastrophic failure, including charring, delamination, and loss of electrical performance. The operating temperature remains below Td is critical for safety and reliability.
How Do You Choose the Right Tg Value for Your PCB Design?
Choosing the right Tg value depends on the operating environment and thermal demands of your application. Consider factors such as the maximum operating temperature, the thermal cycling the PCB will undergo, and the mechanical stresses it will face. Consulting with material suppliers and using simulation tools can help make an informed decision. According to our 18 years experience in PCB, we summarized a recommend Tg value for each application. Hope this is useful for you guys.
Consumer electronics
If your PCB will be used in standard consumer electronics, just like smartphones and tablets, a Tg value of around 130°C to 140°C is typically sufficient. These devices generally do not encounter extreme temperatures or thermal cycling.
Automotive applications
Automotive PCBs are always exposed to high temperatures and significant thermal cycling. A Tg value of 170°C or higher is recommended to ensure reliability and performance under the hood. So, Rogers material is good for this kind of PCB.
Aerospace and defense
Applications in aerospace and defense require materials that can withstand extreme temperatures and harsh environments. High Tg materials with values of 180°C or more are often used to meet these stringent requirements.
Industrial Electronics
Industrial environments can vary widely, but generally, high Tg materials are preferred due to the exposure to high temperatures and mechanical stress. A Tg value of at least 150°C to 170°C is advisable.
Best Technology is a well-known PCB and PCBA assembly provider in Asia and Vietnam. We have a large facility for handling low-medium to mass production PCBs, and supporting for various kinds of custom PCBs. Some special PCBs are available here, like bus bar PCB for new energy vehicles, heavy copper PCB for high power and high current PCBs, ceramic PCBs for harsh environments, extra thin PCB, RF PCB, microwaves PCB, IC substrate PCB and so on.
For more information, please do not hesitate to contact us.
Direct Plating Copper (DPC) is a ceramic circuit board developed on the basis of ceramic film processing. Aluminum nitride/alumina ceramic is used as the substrate of the circuit, and the composite metal layer on the surface of the substrate is sputtered, and the circuit is formed by electroplating and lithography. Its basic processes are:
Incoming Quality Control (IQC)
The process begins with the inspection of raw materials to ensure they meet strict quality standards. This step involves checking ceramic substrates for physical defects such as cracks, chips, or surface irregularities, and verifying material properties like thermal conductivity and dielectric strength. Advanced equipment such as microscopes and X-ray fluorescence (XRF) analyzers are used for thorough inspection, ensuring only the best materials proceed to the next stage.
Laser Drilling
Before laser drilling, a water-soluble, food-grade substrate pigment is brushed onto the ceramic substrate to reduce reflectivity and enhance laser drilling effectiveness. After drying in an oven, a laser drilling machine is used to drill through the substrate, creating pathways for connections between the upper and lower surfaces. Depending on the ceramic material, different laser wavelengths such as infrared, green light, ultraviolet, or CO2 are used to burn away the material with each laser pulse.
Laser Marking
Laser marking involves using a laser marking machine to engrave product QR codes onto the ceramic substrate. This step ensures precise and permanent identification marks on the PCB.
Ultrasonic Cleaning
After laser drilling and marking, the substrates are cleaned to remove any attached particles or residues. This involves coarse and fine debris removal using ultrasonic cleaning, followed by water washing to eliminate any remaining particles. The cleaned substrates undergo micro-etching to roughen the surface, enhancing the effectiveness of subsequent magnetron sputtering, and are then dried to remove surface moisture.
Magnetron Sputtering
In the magnetron sputtering process, a high-vacuum chamber is used to ionize argon gas, producing an ion stream that bombards a target cathode. This causes atoms of the target material to be ejected and deposited as a thin film on the ceramic substrate. Pre-sputtering treatments such as dust removal, degreasing, and slow pulling are conducted to ensure optimal results.
Chemical Copper Plating
Chemical copper plating thickens the copper layer, improving the conductivity of the vias and ensuring better adhesion with the sputtered copper layer. This catalytic redox reaction involves pre-treatment steps like degreasing, micro-etching, pre-immersion, activation, and acceleration to ensure proper copper deposition.
Full-Panel Electroplating
Full-panel electroplating increases the thickness of the copper layer. This involves processes such as degreasing, micro-etching, acid washing, copper plating, and stripping excess copper from the fixtures. The copper plating uses copper balls as anodes and an electrolyte solution of CuSO4 and H2SO4, with the primary reaction being Cu2+ + 2e- → Cu.
Grinding, Laminating, Exposure, and Developing
Post electroplating, the copper layer is prepared for patterning. This includes acid washing to remove oxides, grinding to roughen and clean the surface, laminating with a photoresist dry film, UV exposure through a photomask to create the desired pattern, and developing to dissolve unexposed areas, leaving behind the patterned photoresist.
Pattern Plating (Electroplating Copper)
The exposed and developed areas of the substrate where the circuit pattern is defined undergo further copper electroplating to thicken the circuit traces.
Etching and Stripping
Unwanted copper and dry film are removed through etching, stripping away excess copper deposited in previous steps. This includes rough grinding, film stripping, copper etching, and titanium etching, ensuring only the desired circuit pattern remains.
Annealing
The ceramic boards are annealed in a furnace to relieve stresses introduced during electroplating, enhancing the ductility and toughness of the copper layer and ensuring dense copper grain packing.
Belt Grinding
Post-annealing, the substrate surface may have an oxide layer and rough texture. Belt grinding is used to remove these oxides and smoothen the surface, ensuring the quality of subsequent gold or silver surface treatments.
Flying Probe Testing
High-speed flying probe testers check for continuity and shorts in the vias and circuit traces, ensuring electrical integrity.
Sandblasting Before Solder Mask
Prior to solder mask application, the substrate undergoes sandblasting to roughen and clean the surface, removing oxides and contaminants. This includes acid washing, sandblasting, and micro-etching.
Solder Mask Printing
Solder mask is printed on areas of the PCB that do not require soldering, protecting the circuits during soldering and assembly. Screen printing applies solder mask ink, which is then UV-cured and developed to remove unexposed areas.
Sandblasting After Solder Mask
After solder mask application, exposed areas that need surface treatments undergo sandblasting to roughen the surface and remove oxides, preparing for gold or silver plating.
Surface Treatment
Surface treatments like electroless or electrolytic plating of gold, silver, or other metals are applied to the solder pads, enhancing solderability and preventing oxidation.
Laser Cutting
Laser cutting equipment precisely cuts the finished PCBs from the manufacturing panel, ensuring accurate dimensions and clean edges.
Testing
Various testing equipment, including thickness gauges, Automated Optical Inspection (AOI) machines, and ultrasonic scanning microscopes, are used to inspect the PCBs’ performance and appearance, ensuring they meet quality standards.
Packaging and Shipping
Finally, the PCBs are vacuum-packed using packaging machines to protect them during transport. They are then stored and shipped to customers, ensuring they arrive in perfect condition.
Above is the all the processes of DPC muanufacturing. If you are interested in process of other PCBs, welcome to contact us.
Ceramic PCBs are a special breed of printed circuit boards known for their exceptional thermal resistance and durability. These PCBs are used in industries where high performance is critical, such as aerospace, automotive, medical devices, and power electronics. Nowadays, the most common types of ceramic PCB are thick film, DCB, DPC, AMB, HTCC, LTCC and thin film. In this article, we will introduce each of them in details.
Thick Film Ceramic PCB
Thick film technology is a process by using screen printing conductor paste and directly deposit slurry (conductor) on the ceramic substrate. Then sintering it under high temperature to form conductive circuit traces and electrodes, which is suitable for most ceramic substrates.
After the material is sintered at high temperature, a strong adhesion film will be formed on the ceramic circuit board, repeat this step for many times, a multi-layer circuit is generated.
You can print resistor or capacitor on the surface to get a interconnected structure. At Best Technology, we can make all the resistors with the same value, or different value for different resistor on the same board.
Thick film ceramic PCB has advantages on the simple manufacturing process, but it has some drawbacks that can’t be ignored:
Limited by the conductive paste and screen size
Line width less than 100um is difficult to achieved
Three-dimensional patterns are not available
Not suitable for fine-trace project
DBC / DCB Ceramic PCB
Direct Bonded Copper (DBC) or Direct Copper Bonded (DCB) ceramic PCBs are known for their excellent thermal conductivity. They are made by bonding a layer of copper directly onto a ceramic substrate, typically aluminum oxide or aluminum nitride. Due to the DBC technology is directly bond copper on the ceramic substrate, it can achieve thicker copper thickness to 300um. So, it is very suitable for high power applications.
The basic chemistry principle is to introduce an appropriate amount of oxygen between copper and ceramics before or during the application process. Copper and oxygen will form Cu-O eutectic liquid under 1065℃~1083℃. This is an important element in the manufacturing. DBC ceramic circuit board uses this eutectic solution to chemically react with the ceramic substrate to form CuAlO2 or CuAl2O4, achieving the combination between substrate and copper foil.
However, it is easy to generate micro-porosity between Al2O3 and Copper during the copper bonded process, and it doesn’t have a good solution by far. That is why the yield of DBC ceramic PCB is not good than DPC.
DPC (Direct Plated Copper Ceramic PCB)
DPC ceramic PCB utilizes direct copper plating technology, deposit copper foil on the alumina oxide (Al2O3) substrate. It is the most commonly used ceramic PCB in recent years. The circuit generated process is: pre-treatment – sputtering – exposure – develop – etch – strip – electroplating.
AMB (Active Metal Brazed Ceramic PCB)
AMB ceramic copper clad plate adopts the active brazing process, and the copper layer bonding force is higher than that of DPC, which is around 18n/mm – 21n/mm. AMB ceramic copper clad plate usually has a high binding force, usually makes thicker copper, between 100um and 800um. The AMB ceramic PCB generally rarely design traces or holes, even if there is a trace is very simple, the spacing is relatively wide.
HTCC (High Temperature Co-fired Ceramic PCB)
HTCC is a relatively early development technology, but due to the high sintering temperature (1300~1600℃), the choice of electrode materials is limited. Meanwhile, its cost is more expensive, these promotes the development of HTCC is relatively slow.
LTCC (Low Temperature Co-fired Ceramic PCB)
Although LTCC reduces the co-firing temperature to about 850 ° C, the disadvantage is that the dimensional accuracy and product strength are not easy to control.
Thin Film Ceramic Circuit Board
The thin film ceramic PCB is to deposit a metal layer directly on the surface of substrate by sputtering process. Through lithography, development, etching and other processes, the metal layer can also be graphed into a circuit pattern. Due to the low deposition speed of sputtering coating (generally less than 1μm/h), thin film substrate surface metal layer thickness is small and can prepare high pattern accuracy (line width/line space less than 10μm).
Common Ceramic Substrates
Best Technology is a leading ceramic PCB manufacturer in Asia, our core members has over 20 years manufacturing experience in ceramic PCB fabricating. “High mixed, low volume, high quality, fast delivery” is our advantages and we always try our best to do that, make ourselves better and better. If you are interested in it, feel free to contact us, we are always online.
On July 3rd, 2024, we had India customers visit our office and factory. All our staff of our customer warmly welcome the guest from afar.
Our sales manager Peter, along with Connie and Marina, gave a detailed introduction to our main business and product expertise. They talked about our strict quality control, careful selection of PCB board materials, advanced production equipment, and mature manufacturing processes. Our guests seemed quite impressed with how thorough we are in ensuring top-notch quality.
Actually, we’ve been working with this customer for several years now, and it’s been a fantastic journey of building trust and collaboration. This visit was a great chance to dive into a new PCB project and show off our latest innovations, including electric heating films, ceramic PCBs, and bendable aluminum PCBs.
When checking the sample books, the customers specially mentioned the blind vias and checked the related products for many times. It looks like they are extremely interested in this technology. You know, blind vias, buried vias, through hole vias, micro vias and thermal vias are always our strengthens.
Next day, Connie will be taking our guests on a tour of our metal dome and dome array factory. It’s always exciting to show our partners the heart of our operations and let them see firsthand the dedication and precision that goes into our work.
Best Technology is a one-stop PCB and PCBA service provider in China and Vietnam. “High mix, Low-Middle Volume, High Quality and Fast Delivery” is our advantages. Custom PCBs available in our company as well. You can get high-quality PCB board and PCBA at a very transparent price. For more information, feel free to contact us at any time.
In our daily life, electronic devices are existing everywhere. And there are many people know the “PCB” nowadays, while very less people know the “PWB”. Unless you’ve been in the PCB business for more than 20 years.
Actually, PWB is another term of circuit board, and it was used commonly before the year 1999. But with the development of electronics, it was replaced by PCB gradually. You want to know more about it? In this article, we will answer it for you. Deeply explain their definitions, manufacturing process, applications and the key differences between PCB and PWB.
What is A Printed Circuit Board (PCB)?
A Printed Circuit Board is a fundamental component in modern electronics, providing the physical and electrical connections for various electronic components. It consists of multiple compositions, including a non-conductive substrate, conductive pathways, and insulating layers, which facilitate the complex circuitry required in contemporary devices. A PCB can be made into single sided PCB, double sided PCB and multilayer PCB.
PCBs are integral to the functionality of a wide range of electronic products, from consumer gadgets like smartphones and computers to industrial machinery, medical devices, and aerospace systems. The advanced design and manufacturing processes involved in PCB production ensure high reliability and performance, making them essential in virtually all electronic applications.
Basic manufacturing process of PCB
Design and Layout
PCBs are designed using sophisticated computer-aided design (CAD) software. Designers create detailed layouts, specifying the placement of components, conductive pathways, and vias (interlayer connections). The design is converted into Gerber files, a standard format for PCB fabrication that contains all the necessary information for manufacturing. These files are essential for ensuring precision and accuracy during the manufacturing process.
Material Preparation
The substrate, typically FR4 (fiberglass epoxy laminate), is prepared. FR4 is known for its excellent mechanical strength and thermal stability, making it an ideal base material for PCBs. Copper sheets are laminated onto the substrate, which will form the conductive pathways after the etching process. This preparation stage is crucial for creating a reliable foundation for the PCB.
Printing the Circuit Pattern
A photoresist, a light-sensitive material, is applied to the copper-clad substrate. The board is exposed to ultraviolet (UV) light through a mask that defines the circuit pattern. The UV light hardens the photoresist in the exposed areas. The board is then developed in a chemical solution that removes the unexposed photoresist, revealing the copper to be etched away. This step accurately transfers the circuit design onto the board.
Etching
The board is immersed in an etching solution, commonly ferric chloride or ammonium persulfate, which removes the unprotected copper, leaving only the desired circuit pattern. This etching process is crucial for defining the conductive pathways on the PCB, ensuring that the correct connections are made according to the design specifications.
Drilling
Precision drilling machines are used to create holes for through-hole components and vias. These holes are then cleaned to remove any debris that could affect electrical connectivity. Drilling is a critical step in the PCB manufacturing process as it ensures proper placement and connection of components across different layers of the board.
Plating
The drilled holes are plated with copper to create electrical connections between the layers, which is especially important for multilayer PCBs. Additional layers of plating, such as nickel or gold, may be applied to improve conductivity and protect against oxidation. This plating process enhances the durability and performance of the PCB.
Solder Mask Applying
A solder mask is applied to protect the copper traces from oxidation and prevent solder bridges between closely spaced solder pads. The solder mask is exposed to UV light and then developed to reveal the solder pads. This layer not only protects the PCB but also improves its appearance and reliability.
Silkscreen Printing
A silkscreen layer is printed on the board to add text, component labels, and other identifiers. This layer helps in the identification and assembly of components, making it easier for technicians to work with the PCB during the manufacturing and repair processes.
Surface Finishing
Generally, a layer of surface finishing is coated on the PCB to protect its surface, it also called surface treatment. The common surface treatments are HASL-LF, ENIG, ENEPIG, OSP, Immersion Silver/Tin. Of course, different treatment offers different function, like OSP is to protect surface from oxidation, HASL-LF provides a good solderability, ENEPIG make sure the chemistry corrosion. Choose a suitable one according to your specific demands.
Assembly and Testing
Components are placed on the board using automated pick-and-place machines, and soldered using techniques like reflow soldering for surface-mount devices (SMD) and wave soldering for through-hole components. The finished PCB undergoes various tests, such as automated optical inspection (AOI), electrical testing, and functional testing, to ensure quality and performance. Want see the whole manufacturing process of a multilayer PCB, click here: Manufacturing Process of Multi-layer PCB.
What is the definition of Printed Wiring Board (PWB)?
A Printed Wiring Board is a term historically used to describe a type of circuit board that focuses primarily on the layout and wiring of electronic connections rather than the overall circuit functionality. PWBs emphasize the physical arrangement of conductive paths to connect various components but do not necessarily include all the integrated features found in modern PCBs.
This term was more prevalent during the earlier stages of electronic development, where the primary concern was establishing reliable electrical connections. As technology advanced, the term PCB became more common, reflecting the expanded capabilities and comprehensive role of these boards in forming complete electronic circuits. Despite being less common today, understanding the term PWB is crucial for historical context and certain niche applications.
How to Manufacture A Printed Wiring Board (PWB)?
Design and Layout
PWBs typically have simpler designs focused on wiring patterns rather than complex circuitry. In some cases, the layout may be done manually or using basic design software.
Material Preparation
Simpler substrates such as phenolic or epoxy resins may be used for PWBs. Copper sheets are laminated onto the substrate to form the conductive pathways. These materials are cost-effective and suitable for applications where advanced performance characteristics are not required.
Printing the Wiring Pattern
Similar to PCBs, a photoresist is applied to the copper-clad substrate. The board is then exposed to UV light through a mask and developed to reveal the copper to be etched away. This process creates the wiring pattern necessary for connecting electronic components.
Etching
The board is immersed in an etching solution to create the wiring pattern. This step is straightforward compared to the more intricate etching processes used in PCB manufacturing, reflecting the simpler requirements of PWBs.
Drilling
Holes for through-hole components are drilled, but the process may not require the precision needed for complex PCBs. This basic drilling process is adequate for the less demanding applications of PWBs.
Plating (if necessary)
Plating is done to ensure electrical connectivity but may not involve advanced techniques like those used for multilayer PCBs. It suffices for the simpler construction of PWBs.
Solder Mask Application
A basic solder mask may be applied to protect the wiring pattern. This layer provides sufficient protection for the relatively simple designs of PWBs, preventing short circuits and oxidation.
Silkscreen Printing
A simple silkscreen layer may be added for component identification. This helps in the assembly process but does not require the detailed labeling often necessary for PCBs.
Assembly and Testing
Components are manually or semi-automatically placed on PWBs and soldered using standard techniques. Basic electrical testing is conducted to ensure functionality. This simpler assembly and testing process aligns with the less complex nature of PWBs.
Which Kind of Materials used in PCB and PWB?
Substrate Materials
FR4 (fiberglass epoxy laminate) is the most common substrate material for PCBs due to its excellent mechanical strength and thermal stability. Phenolic resin, used in PWBs for simpler applications, is less durable and has lower thermal stability compared to FR4, but it is cost-effective and suitable for basic electronic devices. Polyimide is used for flexible PCBs due to its high flexibility and thermal resistance, making it ideal for applications requiring bending and flexing, such as wearable electronics and flexible displays.
Conductive Materials
Copper is the primary conductive material for both PCBs and PWBs. It is used to create the conductive pathways and pads, providing excellent electrical conductivity and reliability. Gold, nickel, and silver are used for plating to enhance conductivity and protect against oxidation, primarily in PCBs. These materials improve the durability and performance of the PCB by providing a reliable contact surface for soldering and component connections.
Insulating Materials
Prepreg, a fiberglass cloth impregnated with resin, is used in multilayer PCBs to bond the layers together. Prepreg provides mechanical strength and electrical insulation between the layers. Dielectric materials are used between layers in multilayer PCBs to provide electrical insulation, maintaining signal integrity and preventing short circuits.
Solder Mask Materials
Liquid Photo Imageable (LPI) solder mask is the most common type used in PCBs, providing excellent protection and durability. LPI solder masks are applied using a photolithographic process, ensuring precise coverage and protection. Dry film solder mask is used for simpler applications and PWBs. This type of solder mask is less expensive and easier to apply but may not offer the same level of protection as LPI solder masks.
Key differences between PCB and PWB
Feature
PCB (Printed Circuit Board)
PWB (Printed Wiring Board)
Design and Layout
Designed using sophisticated CAD tools for complex circuitry, including detailed simulation and optimization.
Simpler designs focused on wiring patterns, often done manually or with basic software.
Layer Count
Can have multiple layers (e.g., double-sided, multilayer) to support intricate circuit designs.
Generally single or double-sided, less commonly multilayer.
Component Types
Supports surface-mount technology (SMT) and through-hole technology (THT) components.
Designed to maintain high signal integrity, minimizing electrical noise and interference.
Basic signal integrity management, sufficient for simple applications.
Flexibility and Rigidity
Includes both rigid and flexible PCBs, allowing for a wide range of applications.
Typically rigid, not commonly used in flexible applications.
Terminology and Usage
Universally used in the industry to refer to boards that integrate all necessary components to form complete circuits. Also called “bare board”.
Universally used in the industry to refer to boards that integrate all necessary components to form complete circuits.
Industry Standards
Recognized by standards organizations like IPC, IEC, and ANSI with specific performance and quality criteria.
Covered under broader standards but with fewer specific guidelines due to limited modern use.
Cost and Efficiency
Higher cost due to advanced materials and processes, offering superior performance and reliability.
More cost-effective for simple applications, but with limited performance and reliability.
Applications
Used in consumer electronics, industrial equipment, medical devices, aerospace, and defense.
Historically used in simpler electronic devices and early computers, still relevant in niche applications.
(Summary Differences: PCB VS PWB)
Other Terms Related to PWB and PCB
Based on the PCB and PWB, you may still hear about CCA, PCA, PWA during the PCB working. These terms are also related to printed circuit board. Here is a detailed explanation of each:
Printed Wiring Assembly (PWA)
PWA is the abbreviation for printed wiring assembly. This is an archaic term that was once used to describe what we now refer to as PCB assembly or PCBA. Although it is less common today, understanding this term is useful for historical context and when dealing with older documentation.
Circuit Card Assembly (CCA)
CCA stands for circuit card assembly. It is essentially the same thing as PCBA, where the PCB is assembled with all necessary components to create a functional unit. CCA is a less frequently used term compared to PCBA but is still recognized in certain industries and contexts.
Printed Circuit Board Assembly (PCBA)
PCBA is the abbreviation for printed circuit board assembly. When the PCB is assembled with all its electronic components by SMT technology, it is called PCBA or PCB assembly. Since a change in terminology in 1999, PCBA has become the standard term used for all assembled circuit boards. From users to technical committees, PCBA is the preferred term for referring to assembled boards. The assembly process involves placing and soldering components onto the PCB, making it a functional electronic circuit.
Printed Circuit Assembly (PCA)
PCA stands for printed circuit assembly, which is another term for PCBA. Like CCA, PCA is not commonly used in modern terminology but refers to the same concept of an assembled printed circuit board.
In a word, whatever for PWB, PCB, or circuit cards, they are refer to bare printed circuit boards (bare boards). While PCA, CCA, PWA, and PCBA refer to assembled circuit boards. Among these terms, PCB and PCBA are the most widely used in both industry and technical documentation.
This is the end of this introduction of PWB and PCB, welcome to contact us if you want more about PCB knowledge.
In today’s tech-driven world, creating efficient high speed PCB (Printed Circuit Board) is critical for ensuring devices can handle rapid data transfer without issues. These high speed PCBs are popular in the wireless devices which needs high signal transfer. Crafting high-speed circuits requires careful planning and precise execution to maintain signal quality and overall performance. In this blog, we introduced the basics of high-speed PCB design, offering practical tips and insights into the best materials and techniques for high-frequency applications.
What is a High Speed Circuit PCB?
High-speed PCB is a circuit board that can support signal transmission. High-speed signals usually refer to signals with frequencies higher than 50MHz, such as high-speed digital signals, high-speed analog signals, etc. These fast transitions can introduce challenges like signal reflections, electromagnetic interference (EMI), and crosstalk, which can disrupt performance if not properly managed.
Additionally, these signals will be affected by board materials, layout, wiring and other factors during transmission. Therefore, a specially designed circuit board is required to ensure the integrity and reliability of the signal. Here is a 4 layers high speed PCB for Iradar device with 50ohm single-ended impedance control.
Features of High-Speed PCB
High frequency
Low permittivity and low loss factor
Multilayer design
Strict impedance control
High-precision manufacturing
Low noise characteristic
High density circuit layout (micro-vias)
High performance
What is Considered High-Speed PCB Design?
High-speed PCB design focuses on managing the complexities that come with high-frequency signals and fast switching. Key considerations include:
– Signal Integrity: Ensuring signals travel without distortion or loss.
– Power Management: Distributing power effectively to minimize noise and voltage drops.
– Heat Handling: Managing heat from high-speed components to prevent overheating.
– Impedance Matching: Keeping impedance consistent to reduce signal reflections and loss.
– Differential Pair Routing: Reducing EMI and crosstalk by routing complementary signal pairs together.
This type of high speed pcb design requires a solid understanding of electromagnetic principles, advanced simulation tools, and precise manufacturing techniques. For those new to high-speed PCB design, Best Technology offers expert guidance and solutions.
What’s the Best Material for High-Speed PCB Design?
Choosing the right material for high speed pcb is vital for maintaining signal integrity and achieving optimal performance. The material impacts the board’s dielectric constant (Dk), loss tangent, and overall signal quality. Common materials include:
– FR4: Widely used but not ideal for very high frequencies due to higher loss tangent.
– Rogers (RO4000 series): Preferred for high-speed designs thanks to its low dielectric constant and loss tangent.
– Teflon: Excellent for high-frequency applications but more expensive and harder to process.
Selecting the appropriate material ensures the PCB can handle high-speed signals without compromising performance.
Where is the High-Speed PCB Commonly Used in?
High-speed circuit boards are widely used in signal transmission applications, the typical fields are including:
1. Communication equipment – such as 5G base stations, optical fiber communication equipment, etc.
2. Data center – like high-performance computing, storage servers, etc.
3. Consumer electronics in our daily life – high-end smartphones, tablets, gaming devices, etc.
4. Aerospace and military – high speed are always used in high-end devices. For example, radar, navigation systems and other equipment with high reliability requirements.
What is the 3H Rule in High Speed PCB Design?
The 3H rule is a guideline suggesting that signal traces should be spaced at least three times the height of the dielectric (3H) between the signal layer and the adjacent ground or reference layer. This helps minimize crosstalk and maintain signal integrity, particularly for high-speed digital signals with rise times of 1 ns or less. Key aspects include:
– Trace Spacing: Keeping traces apart by at least 3H reduces electromagnetic coupling and interference.
– Signal Integrity: Adequate spacing helps maintain clear signals in high-speed circuits.
– Effectiveness: This rule is especially beneficial for fast digital signals, reducing the risk of crosstalk and interference.
For instance, if the dielectric height between the signal layer and the reference layer is 0.2 mm, traces should be at least 0.6 mm apart to follow the 3H rule.
How to Design a High-Speed Board?
Designing a high-speed PCB involves several strategies to ensure effective signal transmission, power distribution, and minimal EMI. Here’s a step-by-step approach:
Component Placement and Layer Stack-Up
Place high-speed components to minimize signal paths and interference. Group related components to simplify routing. In addition, create a layer stack-up that supports controlled impedance and reduces signal loss. Use ground planes between layers for a return path for high-frequency currents.
Trace Routing and Impedance Control
Keep high-speed traces short and direct, avoiding right-angle bends. Use microstrip or stripline configurations for controlled impedance and minimal noise. For impedance control, calculate and ensure consistent impedance for traces. Use differential pair routing for high-speed signals to reduce EMI and crosstalk.
Power Distribution and EMI Mitigation
Use decoupling capacitors near high-speed components to filter noise and stabilize the power supply. Design a robust power distribution network to minimize impedance and ensure stable voltage. And employ proper grounding and shielding techniques. Route high-speed signals on inner layers between ground planes to reduce EMI and provide a consistent return path.
Simulation and Testing
Use signal integrity analysis tools like SI or PI to simulate the PCB layout, predicting signal behavior and identifying potential issues. Analyze aspects like eye diagrams to assess signal quality.
High-speed PCB design is a complex but rewarding endeavor that ensures your electronics perform efficiently in high-frequency environments. By understanding the fundamentals and applying the right techniques and materials, you can create robust, high-speed boards. Best Technology is here to assist you with expert advice and solutions for your high-speed PCB needs.
