Archive for the ‘FR4 PCB’ Category

What Are Stamp Holes and What’s the Design Standard About It?

Monday, May 6th, 2024

Have you ever seen several small holes on the rails of the PCBs or located at the board edges? They look like trails bites by mouse, do you know what they are? And what’s the function of these? This blog may make you sense about it.

What is Stamp Hole on PCB and its Purpose?

Stamp holes, also sometimes called breakaway holes or mouse bites, are small holes drilled in a row or array along the rails or edges of each circuit board within the panel. They look like the edges of a stamp, so people call it “stamp holes”.

Stamp hole is used primarily in the process of depanelized PCBs. De-paneling is the process of separating individual PCBs from a larger panel, which is a common method in PCB manufacturing to improve production efficiency and reduce costs. The larger panel makes handling and processing multiple PCBs easier during the manufacturing process. In some ways, panel also improves the utilization of the raw materials. Once the manufacturing steps are complete, the individual PCBs need to be separated for use in their corresponding devices. And these holes between the single PCBs can create a weak point along which the boards can be easily broken apart after manufacturing be completed.

stamp holes on pcb

Why Use Stamp Holes Expertise In PCBs?

It is possible to use stamp holes if the boards are abnormal shaped or round. The stamp hole is connected between each circuit boards, which mainly plays a supporting role and avoid PCB be scattered. Most commonly, they are used to create PCB stand-alone modules, such as Wi-Fi, Bluetooth, or core board modules, which are then used as stand-alone components placed on another board during PCB assembly.

The use of stamp holes allows for a relatively clean break along the separation line, but it may leave behind rough edges or require additional finishing steps to smooth out the remnants of the perforation points. This method of depaneling is a cost-effective solution and can be used for various types of PCBs, but it might not be suitable for very delicate circuits or when a perfectly smooth edge is required. In addition, V-cut and hollow connection strips also are the common depaneling ways for PCBs.

stamp holes on pcb

What are differences between Stamp Hole, V-cut and Hollow strip?

When preparing a panel for the manufacturing of multilayer PCBs, it’s essential to consider a method used to connect individual boards within the panel. As mentioned above, there are three connection methods for PCB technology, each serving different types of PCB designs and requirements. So, which one is the better or how to choose a suitable one for your project? Welcome to keep reading.

V-Cut (V-slot)

V-cut is the most common way to separate the PCBs during the circuit board manufacturing. It mainly utilizes for PCBs with straight edges or straight lines. This method involves cutting a V-shaped groove along the line where two PCBs are connected within the panel. When implemented, V-cuts leave a narrow gap (the width of the V-cut itself) between the boards. V-cut depth is an essential point during the process, make sure it has 1/3 depth on top and bottom side. The V-cut is especially suitable for standard, rectangular PCB designs, allowing for a clean and efficient separation of the boards once all other manufacturing processes have been completed.

Stamp Holes

For PCBs with unique or irregular shapes, stamp holes are often the preferred method of connection. Its process involves drilling multiple small holes in an array at the points where the individual PCBs connect within the panel. These holes create a perforated line that weakens the material enough to facilitate easy separation of the boards by applying minimal force, without compromising the integrity of the circuitry. But this way can only be used if you don’t have strict requirements for burrs on edges. And it is easy to damage the whole board if use improper approach.

Hollow Connecting Strips

Hollow connecting strips are used in scenarios where a very narrow strip of material is left to connect the boards within the panel. This method is particularly useful for PCBs utilizing half-hole (castellated holes) technology. The narrow strips maintain the alignment and integrity of the PCBs during the manufacturing process but can be easily removed or broken away to separate the individual boards. Hollow strip is less common but essential for specific designs and technologies.

Each of these connection methods has its specific applications, advantages, and considerations. The choice between V-cuts, stamp holes, and hollow connecting strips depends on the design of the PCB, the requirements of the manufacturing process, and the desired ease of separation post-manufacturing.

How to Add Stamp Holes on Your Circuit Board?

Designing stamp holes is a critical step in preparing your PCB for the depaneling process. This includes creating a series of small holes along the intended lines of separation between individual boards in a panel. Here’s a step-by-step guide to help you incorporate stamp holes into your PCB design effectively:

1. Understand the Purpose

Recognize that stamp holes are used to facilitate the manual separation of PCBs from a panel after the manufacturing process, minimizing the risk of damage to the board and its components.

2. Plan Your Layout

Placement: Decide where the stamp holes will be located on your PCB layout. They should be placed along the edges where the PCB will be separated from the panel.

Number and Spacing: The number of stamp holes and their spacing can significantly affect the ease of PCB separation. Typically, a distance of 0.5mm between holes and 1.0mm between centers of holes are used, but this may vary based on the PCB material and thickness.

3. Select the Hole Size and Quantity

The diameter of stamp holes usually ranges from 0.6 mm to 1 mm. The size may depend on your specific requirements and the capabilities of your PCB manufacturer. As for quantity, 5-8 holes in an array is good (always 2 arrays/rows), more also is available, it can be adapted based on your specific needs.

4. Arrangement of Stamp Holes

Two rows of stamp holes should be added at the edge of the PCB, extending slightly into the board. This design ensures that any burrs left on the board edge after separation will not affect the PCB’s overall dimensions. If there are traces or other critical components on the edge of the board, ensure that the stamp holes are placed to avoid damaging these elements during separation.

5. Design Using PCB Design Software

Use your PCB design software (such as Altium Designer, Eagle, or KiCad) to add the stamp holes to your design. This can usually be done by placing a series of via or pad holes along the separation lines.

Some software packages may offer tools to automate this process, allowing you to specify the number of holes, their spacing, and diameter, and then automatically place them along a line.

6. Consult with Your Manufacturer

Before finalizing your design, consult with your PCB manufacturer for any specific guidelines or requirements they have for stamp holes. This can include preferred sizes, spacing, and any additional considerations to ensure the depaneling process goes smoothly.

Provide detailed documentation of your stamp hole design to your manufacturer to avoid any confusion during the production process.

7. Review and Adjust

After adding the stamp holes to your design, review the layout to ensure that there is adequate clearance between the holes and any nearby components or traces. This is crucial to avoid damage during the separation process.

Adjust the size, spacing, and number of stamp holes as necessary to meet both your design requirements and the manufacturer’s capabilities.

stamp holes on RF pcb

In the design process, these considerations should be adjusted based on the specific PCB design and manufacturing requirements. Moreover, find a reliable PCB manufacturer to ensure these design details are accurately implemented is key to successfully fabrication.

Best Technology specializes in PCB manufacturing for more than 17 years, offering comprehensive PCB production and design services to over 200 countries worldwide. To ensure the best quality and fast delivery, we set up a strictly quality control system according to ISO9001 and equipped with advanced measured devices such as AOI, X-RAY, 2D, 3D measurement tools in our factory. We provide 24/7 hours service and commitment with a timely reply within 10 hours. We sincerely appreciate your any comments or consults, welcome to contact us at any time.

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What Is the Importance of Ground Plane in PCB EMC Design?

Saturday, March 30th, 2024

In the design of electronic products, electromagnetic compatibility (EMC) is a crucial consideration. Particularly in the design of printed circuit boards (PCBs), the rationality of EMC design directly impacts the performance and stability of the product. Among the many factors affecting EMC, one factor is especially critical, and that is the design of the ground plane. Today, let’s talk about the impact of grounding on EMC.

In an electronic product, grounding is a very important element, it is directly related to EMC compliance. Especially in large equipment, the grounding of multiple systems and subsystems is involved. It can be said, a good grounding system means the half successfully of a product.

What are Ground Plane and EMC in a PCB?

The ground plane, as the reference potential in a circuit, not only carries the return path of current but also plays a role in electromagnetic shielding and noise suppression. In high-frequency circuits, the impedance and layout of the ground plane have a significant impact on signal integrity. Unreasonable ground plane design may result in signal interference, increased radiation, and decreased system stability.

EMC stands for Electromagnetic Compatibility. It refers to the ability of electronic devices and systems to operate properly in their intended electromagnetic environment without causing or experiencing interference. EMC ensures that devices can function without adversely affecting other devices nearby or being affected by electromagnetic interference from external sources. Generally, the ground planes will showing three shapes, please see as following:

Why A Grounding Must be Designed in PCB?

Grounding can be understood as an equipotential point or plane serving as the reference potential for a circuit or system, which can be a specific ground layer in a PCB or the metal chassis of a product. While many perceive the purpose of designing a ground plane primarily to prevent external electromagnetic interference (EMI), but in printed circuit board design, it serves multiple purposes beyond this.

Generally, a well-designed ground provides a common reference zero potential for all circuit units within a system, ensuring no potential difference between circuits and thus stable operation. It also protects circuits from damage, ensuring the safe functioning of electronic products. For instance, ground can provide discharge paths for transient disturbances and dissipate accumulated charges on product metal enclosures induced by static electricity, to prevent potential sparks that may cause interference internally. Additionally, choosing appropriate grounding for shielding structures can yield effective electromagnetic shielding.

Grounding design is very necessary especially for medical industry. As we know, there are many medical devices are directly connected to patients’ bodies, such as monitors. In cases where the chassis carries voltage due to poor grounding, fatal risks may arise. Furthermore, grounding reduces common-mode interference currents flowing through PCBs and prevents high-frequency EMI signals within products from reaching equivalent radiating antennas. Thus, grounding is typically a primary method for noise suppression and interference prevention.

Design Principles of Ground Plane in PCB

A well-designed grounding system should not only consider the radiation and conduction of individual PCBs but also prevent from a systemic perspective. In the design phase, failure to carefully consider the grounding system may indicate a high likelihood of EMC failure for the system. So, knowing the design principles is extremely important to make sure the successful of EMC.

  • Keep it short and wide

To reduce the impedance of circuits, especially in high-frequency circuits, the ground plane should be made as short and wide as possible. This helps to minimize the return path of the current, thereby reducing EMI.

  • Partition layout

For complex PCB designs like multilayer PCBs, it is recommended to use a partition layout to separate the ground planes of different functional modules. This helps to isolate noise interference between different modules.

  • Single-point ground and multipoint ground

Depending on the circuit’s operating frequency and signal characteristics, choose between single-point grounding or multipoint grounding. Single-point grounding is suitable for low-frequency circuits, while multipoint grounding is more suitable for high-frequency circuits.

PCB_ground_plane_design
  • Ground plane

Where possible, use a ground plane as the ground. The ground plane can provide a low-impedance return path and aid in electromagnetic shielding.

How to Optimize Your Grounding Design?

As for PCB that has already design the circuit layout, how to optimize the ground to get the maximum EMI? Here are some tips that may helpful for you.

  • Fill the blank areas of the PCB with ground planes to increase the ground plane’s area and reduce impedance.
  • Reducing the area of ground loops helps to decrease electromagnetic radiation and induced noise.
  • Power lines and ground planes should be placed as close as possible and run parallel to reduce the area of the current loop.
  • Placing decoupling capacitors between power and ground planes helps to filter out high-frequency noise.
Semi_flexible_pcb

In PCB EMC design, ground plane design is an essential step that cannot be ignored. By following the principles and optimization methods of ground plane design, the EMC and signal integrity of electronic products can be significantly improved. Therefore, in PCB design, sufficient attention and consideration must be given to ground plane design. Welcome to contact Best Technology if you want to know more about ground and EMC design.

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Top 6 Considerations You Must Know About PCB Designs

Wednesday, March 27th, 2024

Electronics devices and parts are existing everywhere in this big data era, and more and more engineers trying to step in the electronics design and development. As a one-stop PCB and PCBA manufacturer in China, Best Technology would like to share some basic considerations and tips during the PCB designs. Hope this can help you.

Substrate Material

Substrate is the main composition of a circuit board and it mainly used for suppler and copper foil insulation. The commonly materials are FR4 and PI. FR4 is a widely acceptable international grade for fiberglass reinforced epoxy laminated, and it always used for making rigid PCB or rigid-flex PCB. FR4 substrate has good insulation and mechanical strength, so it can be widely used in various applications. However, PI has higher heat and chemistry resistance, more suitable for high temperature and chemical corrosion environment.  

Circuit Layout

The layout design depends on the dimensions, performance and reliability of a circuit board, it is needed to follow your supplier’s standard to make sure the fast production time and high quality.

  • Min line width

Please make sure your line width within your supplier’s manufacturing capability, that is to say, if it is less than the minimum line width will not able to be produced. The best way is if the design conditions available, the larger the line width, the better the factory production. Generally, the line width keeps around 10mil is the best. In another word, if your line width is less than normal standard, it would be difficult for you to find a suitable supplier.

  • Min line spacing

Min line spacing means the distance between trace and trace. Normally, from the production aspect, the distance from line to pads should not less than min line spacing, and it would be better if it is larger, generally equal to or more than 10mil.

  • The spacing between circuit to outline should be control in 20mil.

Plug-in Hole

The diameter of plug-in hole should be considered by the side of components, but it is necessary that it must greater than the component’s pins, it is recommended that greater at least 0.2mm. That is to say, if the pin of components is 0.6mm, then the plug-in holes should be greater than 0.8mm. Otherwise, the plug-in components would be probably difficult to insert into PCB because of the tolerance control during the manufacturing and assembly

Min Hole Diameter

As we all know, the holes in PCB almost be used for mounting components, connect circuit and provide the electrical connection between layers. So how to design the hole also is crucial during the designing. Generally, the min hole diameter depends on the drill bitter that vendor used, always around 0.2-0.4mm. You can ask your supplier during the design evaluation.

Copper Thickness

Copper foil is a layer of metal foil on the PCB board that is used to conduct current. The thickness of copper foil is usually in oz (ounces), such as 1oz, 2oz, 3oz, etc. The thickness of the copper foil will affect the conductivity and heat dissipation performance of the PCB board.

Impendence Control

Impedance control is a key parameter in high-speed signal transmission and high-frequency circuit design. It involves board thickness, copper foil thickness, substrate dielectric constant, pad and line layout and other factors to improve the signal integrity and anti-interference ability of the PCB board.

The production process of PCBs is rather complex, involving a wide range of techniques from simple mechanical processing to sophisticated machining, so you should understand the design rules very clearly when you are trying to design a PCB board. Its applications are also diverse, from consumer electronics to industrial machinery, where PCBs are utilized.

Best Technology offers one-stop PCB solutions, we offer service from prototyping to large-scale production and assembly. With experienced engineers and service teams, we ensure successful fulfillment of your requirements. Just send us with your design files, and we will make the circuit board for you in a very short time.

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What Is Immersion Silver? Why Choose It for PCB Coating?

Monday, February 26th, 2024

Due to the growing concerns and advocacy for environmental friendliness, as well as the prohibition of harmful substances like lead (tin), an increasing number of industries are moving away from the use of HASL (Hot Air Solder Leveling) technologies for PCB (Printed Circuit Board) surface treatment. The current trend is to use other surface treatments such as OSP, gold plating, immersion tin, immersion silver, ENIG and ENEPIG. Among them, immersion silver becoming a popular choice since it has excellent performance and cost effectiveness.

What is Immersion Silver Finish?

Immersion silver finishing is an environment friendly surface treatment that coating a layer of silver (about 0.1~0.4um) on the copper surface to ensure the good solderability when assembly. When comparing its functional performance with other surface finishes like OSP and ENIG, immersion silver falls between them. It exhibits outstanding solderability and exceptional solder joint strength, surpassing OSP, which lacks a conductive barrier. However, when employed as a contact surface, immersion silver demonstrates lower strength compared to gold.

What is the Working Principle of Immersion Silver?

Immersion silver finishing uses chemical deposition to finish the whole processes. Electrochemical deposition is a method of reducing and depositing metals onto the surface of an object by controlling the current in a solution. In the immersion silver process, the pad serves as the anode (positive electrode), while silver acts as the cathode (negative electrode), with a current applied between them. This causes silver ions (Ag+) to be reduced to silver metal under the influence of the electric field, subsequently adhering to the pad surface and gradually forming a silver layer.

The displacement reaction of immersion silver is:

2Ag+ + Cu = 2Ag + Cu++

This method utilizes both electrical current and chemical reactions to deposit silver from the solution onto the surface of the PCB pad, creating a uniform and porous silver layer.

Silver Plated Analyzing: Pros vs Cons

Before selecting the immersion silver coating, we should understand its advantages and disadvantages to consider whether it is suitable for your PCB project and end-applications.

Pros of immersion silver:

  1. Cost-effective than immersion gold
  2. Good surface flatness and low contact resistance
  3. Corrosion resistance
  4. Good solderability, especially for BGA chips or smaller components
  5. Environment friendly
  6. High reliability

Cons of immersion silver:

  1. Difficult to handle, must wear gloves
  2. Special storage conditions – if the package is opened and not all PCBs need to be used, it must be resealed quickly or use them within 24h.
  3. Peelable masks can’t to use

Important Points You Must Know About Storage

  1. For storage and handling, it needs more careful than immersion tin and OSP.
  2. It is compliant with ROHS and safer than HASL.
  3. In the dry conditions, it can be stored 6-12months.
  4. PCB with immersion silver must be soldered within 24hours if package is unsealed.
  5. If the immersion silver PCB has been stored for more than 12 months, a solderability testing is must before assembling.

Immersion Silver vs ENIG

ENIG also is a common surface treatment in the PCB manufacturing, its full name is Electroless Nickel/Immersion Gold finishing. The ENIG technology is a relative expensive than immersion silver, and it suitable for more complex layout design.

ENIG plating involves safeguarding the copper pads on PCBs by first applying a layer of nickel and then overlaying the copper surface with a thin layer of gold. In essence, the procedure is akin to immersion silver, but it significantly improves PCBs by providing enhanced resistance to oxidation, superior solderability, and excellent surface planarity.

Let’s review the performance comparison between these two surface treatments:

Welcome to contact us if you have any questions about immersion silver or other surface treatment.

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What Are Differences of ENIG VS ENEPIG in PCB Manufacturing – Series 2

Tuesday, January 2nd, 2024

In our last blog, we simply introduced ENIG surface treatment in PCB manufacturing, and this time, we will share more information about the comparison of ENIG and ENEPIG.

What is ENEPIG Surface Treatment?

ENEPIG stands for Electroless Nickel Electroless Palladium Immersion Gold. This type of metal coating on the PCB pad surface consists of three layers—nickel, palladium, and gold. Apart from protecting the copper surface from corrosion and oxidation, the ENEPIG surface treatment is also suitable for high-density SMT (Surface Mount Technology) designs.

For its manufacturing process, manufacturers begin by activating the copper surface, followed by depositing a layer of electroless nickel, then a layer of electroless palladium, and finally, a layer of immersion gold. The process is somewhat similar to the one they follow in the ENIG process, but adding a palladium layer to the ENIG technology. The palladium layer not only improves the surface protection of the PCB, but also prevents nickel from deteriorating and inhibits interactions with the gold layer.

Pros of ENEPIG Surface Treatment

  • Reduce the black pad issues
  • Excellent solderability and high reflow soldering performance
  • Provide high-reliable wire bonding capability
  • High-density design available
  • Meet the miniaturization standards
  • Suitable for extra thin PCBs

Cons of ENEPIG Surface Treatment

  • Expensive than ENIG process
  • Thicker palladium layer will decrease the effective of SMT soldering
  • Longer wettability time

What are the Differences Between ENIG and ENEPIG?

The main difference between ENIG and ENEPIG is the palladium layer. This is the extra layer that added in ENEPIG process, which provides high oxidation resistance, enhance the electrical performance of the surface cleanliness and improve the abrasion resistance of the PCB surface. However, the palladium layer also increases the cost of manufacturing.

Additionally, the inconsistent surface cleanliness of ENIG, resulting from low solder joint reliability, particularly in gold wire bonding, is a concern. Extra procedures are also required to prevent nickel corrosion in ENIG. When considering it into manufacturing, the ENIG is well-suited for lower-end electronic products.

(ENIG_VS_ENEPIG)

The Considerations of Selecting ENIG or ENEPIG Surface Finishing

Though both two surface treatments offer excellent electrical performance and heat dissipation properties, there are still some conditions that need to consider when choose them.

  • Budget

Cost is an important factor when choose a suitable surface treatment. As we explain above, ENEPIG is expensive than ENIG, if you are trying to find a relative cost-effective coating, then ENIG is the best choice.

  • End-applications

The end-applications or finished products also determined the selection of surface finishing. For example, if your PCB will be used in high temperature applications, ENIG would be the better one since it can withstand high temperature.

  • Flatness

Many traditional surface finishes have poor flatness and smoothness, this brings the big challenge of small-size components mounted. Especially for those fine-pitch components like BGA, an uneven surface can result many problems. However, both ENIG and ENEPIG offer highly smooth surface finishes, forming thin and uniform layers on the solder pads.

  • Bonding demand

ENEPIG provides the optimal choice for wire bonding due to its highly smooth surface finish, which enhances wire bonding capabilities.

  • Environment-friendly

Some traditional surface treatments contain hazardous substances, making them non-compliant with RoHS requirements. Both ENIG and ENEPIG made by Best Technology are fully RoHS compliant and lead-free, so you are don’t worry about the environment unfriendly.

At the end, the choice between ENIG and ENEPIG surface treatments in PCB manufacturing involves a careful consideration of various factors. While both options offer excellent electrical performance, heat dissipation properties, and compliance with environmental standards like RoHS, specific project requirements and priorities will guide the decision-making process. If you are still confuse about the selection of surface treatment, welcome to contact with us, Best Team will give you a best solution that can meet your specific demands and save money for you.

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What Are Differences of ENIG VS ENEPIG in PCB Manufacturing – Series 1

Tuesday, January 2nd, 2024

Surface treatment also called surface finishing, it is a protective layer that through coating a layer of metal organic material on the surface of printing circuit boards (PCBs). Apply a layer of surface treatment enable to protect pads from scratches and oxidation, as well as improve the solderability of components mounting. ENIG and ENEPIG are the two common high-reliable surface finishing types in the circuit board manufacturing, they are not only for FR4-PCB, but also available in ceramic PCB, flex circuits and rigid-flex PCB. Today, Best Team would like to sharing information about ENIG and ENEPIG, and explore the differences between them.

(Assembled_PCB)

How to Select the Right Surface Treatment for Your PCB?

With the rapid development of electronics, there are various of PCB types that can be used in electronic devices, and at the same time, there are also increasingly more surface treatment technics available for selection. Until now, the common surface treatments are OSP, HASL, Immersion Silver, Gold Plating, ENIG and ENEPIG. Each of these surface treatments has its own advantages and disadvantages, so it is necessary to choose the most suitable one for a particular application. The selection of surface finish needs to take into account factors such as cost, application environment, fine-pitch components, the use of leaded or lead-free solder, operating frequency, shelf life, drop and impact resistance, volume and throughput, as well as thermal resistance.

With PCBs trending towards micro-vias and finer traces, and the drawbacks of HASL and OSP, such as flatness and flux elimination issues, becoming more pronounced, the demand for surface treatments like ENIG continues to grow. In addition, black pad is a major weakness of ENIG while ENEPIG enable to solve it very well, making it a preferred choice for those PCBs need to wire bonding.

What is the ENIG Surface Treatment?

ENIG, its full name is Electroless Nickel Immersion Gold, is also known as chemical gold or immersion gold in the electronics industry. This type of surface treatment provides two metal layers—gold and nickel—that manufacturers deposit them on the surface of PCB pads sequentially. This surface finish is a selective surface finish, meaning that certain specific pads may have ENIG surface finish, while others may have different types, such as OSP, HASL, or immersion tin. Here are the main processes of the ENIG coating:

  • Copper activation

In this step, manufacturers will active the copper layer through cleaning process, this way can help to remove the dust and oxides residual on the surface, but also remove any gases or air trapped in the perforations (holes) of the PCB by wetting the surface. Next, micro-etching the PCB surface using substances like hydrogen peroxide or sulfuric acid.

  • Electroless nickel

This process is to coat a layer of nickel on the active copper layer by electroplating. The nickel layer serves as a protective layer or inhibitor, which prevent the copper reactive with other elements.

  • Immersion gold

Immersion gold is the last step of whole ENIG process, immersing the PCB into a mixture, oxidizing the nickel surface, generating nickel ions, and then reducing gold from the mixture. The reduced gold forms a metallic coating to protect the nickel surface. This is the whole process of coating ENIG surface treatment.

(PCB_with_ENIG_surface_treatment)

Advantages of ENIG

  • Surface flatness – good for fine-pitch and small size components like BGA.
  • Suitable for press-fit components since it provides a reliable connection for electrical testing.
  • Suitable for wire bonding and gold-fingers connectors.
  • Cost-effective compared with ENEPIG

Disadvantages of ENIG

  • Black pad issues.
  • Varied coating thickness because of the uncontrolled nickel plated and immersion gold.
  • Poor wettability during PCB assembly.

All in all, ENIG is a good option if you want to mount fine-pitch components on the PCB surface or if you are considering its use in plug-and-pull devices such as WIFI interfaces. In our next blog, we will introduce ENEPIG surface treatment, including its pros & cons and the differences between ENIG and ENEPIG. Pay attention to our news or contact us directly if you want to know more.

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What is a E-Tester & how E-tester test PCB?

Saturday, December 2nd, 2023

We often receive this question from customer” what is a E-Tester?” and” how to do E-Test for FR4 PCB?” Hereby I would like to share with you how to use E-Tester to test PCB.

Best Technology in FR4 PCB circuit manufacturing filed since year 2006, we have more than 17 years experiences in PCB fabrication process. We can provide from the design to turn key service for our customer.

Let us come to today’s topic, now what is a E-Tester?

What is a E-tester?

E-Tester is tooling for test PCB during volume production. E-Tester was used to detect the electrical performance of PCB. It is the essential process to test the PCB by this tester before shipment.

As you may know that during PCB process flow, it might be caused some defects by external factors and this is unavoidable.

So, in order to reduce the loss before PCB goes to the next stage when it is assembled with components, Therefore, the E-Test plays important role in PCB quality control to segregate PCBs with defects from shipment to customers and that’s why most of customers require their PCB manufactures to do 100% E test before shipment.

(E_testers)

The E tester mainly checks the open/short circuit for FR4 PCB.

How to do E-test?

Firstly, set up the E-tester on the testing machine and up test datasheet on the computer. Put the board to the E-tester to test the open/short circuit for board and dielectric strength.

Shorts Test: Check to make sure that NO current flows between separate nets by measuring the amount resistance between them.

Opens Test: Check to make sure there is current flow from one “node” to the next for every net on the board.

(Tester_testing)

During the testing, test whether there is short circuit between different network routes of PCB; test whether the PCB network is open to each PAD, and whether the hole is open; Finally, Insulation strength test and the Impedance test.

If the trace open is found on the bare board, the failure location could be repaired or the bare board has to be scrapped. On the other hand, the cost will be increased when PCB goes to the next stage when it is assembled with components, mainly are the sorting cost, component cost and the assembly cost. The compensation ratio is 10 times or even more than the PCB cost and this damages PCB manufacturer’s profit. The worse case is when PCBA is installed onto the end product, the loss caused by defected PCB could be very painful, say up to thousand times of PCB cost. Therefore, the E-Test plays important role in PCB industry to segregate PCBs with defects from shipment to customers and that’s why most of customers require their PCB suppliers to do 100% E test before shipment.

If you want to know more about testing for FR4 PCB board, welcome to visited www.bestpcbs.com or email us, we are very happy to answer your question.

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What is PCB Embedded Component Process?

Wednesday, November 22nd, 2023

The resistance and capacitance buried in multi layers PCB process is a process of burying resistors and capacitors inside the PCB board. Usually, the resistors and capacitors on the PCB are directly soldered on the board through mounting technology, while the buried resistor and capacitor process is to embed the resistors and capacitors into the internal layer of the PCB board.

This kind of printed circuit board consists of a first dielectric layer, a buried resistor, a circuit layer and a second dielectric layer in order from bottom to top. Among them, the part of the buried resistor without a circuit layer on the buried resistor is covered with a polymer isolation layer, and the surface of the polymer isolation layer is roughened, the surface roughness Rz is bigger than 0.01 μm, and the thickness of the polymer isolation layer at the corners is at least 0.1 μm.

The printed circuit board of the utility model covers a layer of polymer isolation layer on the surface of the buried resistor, thereby protecting the buried resistor from being attacked and corroded by chemical chemicals during subsequent wet processes such as browning and super-coarseness, and improving the efficiency of manufacturing buried resistors. Resistor plate process capabilities further promote the application of buried resistive plates to inner layer buried resistors.

The advantages of the buried resistor and buried capacitor process include:

1. Space saving:

Since the resistors and capacitors are embedded directly into the internal layers of the board, space on the PCB board can be saved, making the entire circuit board more compact.

2. Reduce circuit noise:

Embedding resistors and capacitors into the internal layers of the board can reduce the electromagnetic interference and noise of the circuit and improve the stability and anti-interference capabilities of the circuit.

3. Improve signal integrity:

The buried resistance and buried capacitance process can reduce the transmission delay and reflection loss of circuit signals and improve the integrity and reliability of signal transmission.

4. Reduce the thickness of the PCB:

However, the buried resistor and buried capacitor process is relatively complicated in terms of manufacturing and repair, because the resistors and capacitors cannot be directly observed and replaced. In addition, the buried resistance and buried capacitance process is usually used in high-end electronic products, and the cost is relatively high.

When it comes to high-density circuit design, PCB buried resistance and buried capacitance technology has become a very useful technology. In traditional PCB layout, resistors and capacitors are usually soldered on the PCB surface in the form of patches. However, this layout method causes the PCB board to take up more space and may cause noise and interference on the surface.

The buried resistance and buried capacitance process solves the above problems by embedding resistors and capacitors directly into the internal layer of the PCB board.

The following are the detailed steps of the PCB buried resistor and buried capacitor process:

1. Make the inner layer:

When making a PCB board, in addition to the conventional layers (such as outer layer and inner layer), it is also necessary to make a separate inner layer specifically for buried resistance and buried capacitance. These internal layers will contain areas for buried resistors and capacitors. The inner layers are usually made using the same techniques as regular PCB manufacturing, such as electroplating, etching, etc.

2. Resistor/capacitor footprint:

Resistors and capacitors are packaged in a special package in the buried resistor and capacitor process so that they can be embedded into the internal layer of the PCB. These packages are usually thinned to accommodate the thickness of the PCB board and have good thermal conductivity.

3. Buried resistor/capacitor:

In the process of making the inner layer, the buried resistor and capacitor process is completed by embedding resistors and capacitors into the inner layer of the PCB board. This can be achieved through a variety of methods, such as using special pressing techniques to embed resistors and capacitors between inner layers of material, or using laser technology to etch holes in the inner layer material and then fill them with resistors and capacitors.

4. Connection layer:

After completing the inner layer of the buried resistor and buried capacitor, connect it to other regular layers (such as the outer layer). This can be achieved through conventional PCB manufacturing techniques such as lamination, drilling, etc.

In general, the buried resistance and buried capacitance process is a highly integrated technology that embeds resistors and capacitors in the internal layer of the PCB board. It can save space, reduce noise, improve signal integrity, and make PCB boards thinner and lighter. However, due to the complexity, the buried resistor and buried capacitor process is usually used in high-end electronic products with higher performance requirements.

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Do You Know How Does the ENEPIG Working for Wire Bonding Circuit Boards?

Friday, November 10th, 2023

The electronics industry has continuously pursued smaller and faster electronic products with increased functionality. To meet these demands, the electronic packaging industry has focused on developing more advanced packaging methods, aiming to increase the density of components on a circuit board while integrating multiple functions into a densely package.

The increasing density of packaging and interconnection has driven the progression of assembly methods from through-hole technology (THT) to surface-mount technology (SMT). Additionally, the use of wire bonding to connect chips to substrates has become more prevalent. The adoption of smaller interconnect pitches and chip-scale packaging (CSP) has further increased component density, while multi-chip modules (MCM) and system-in-package (SiP) have enabled the integration of more functions on a single package.

This post describes the key factors affecting the reliability of interconnections, with a particular focus on the specific properties of surface-treated wire bonding, emphasizing the selection of wire bonding surface treatments.

Selection of Surface Treatment for Wire Bonding

While electroless nickel gold provides excellent performance for wire bonding, it has three main drawbacks that hinder its application in cutting-edge technologies:

1. The relatively high demand for gold layer thickness leads to lengthy process costs.

2. Thick gold layers are prone to the formation of weak tin-gold intermetallic compounds (IMC), reducing the reliability of solder joints. To enhance solder joint reliability, alternative surface treatments may be used, but this increases additional process costs.

3. The electroplating process requires the use of electroplating lines, limiting the design freedom and wiring density of the packaging substrate.

The limitations posed by electroplated nickel-gold provide an opportunity for the adoption of chemical plating. The techniques of chemical plating include Electroless Nickel Immersion Gold (ENIG), Electroless Nickel Electroless Gold (ENEG), and Electroless Nickel Palladium Immersion Gold (ENEPIG).

Among these three options, ENIG is generally unproblematic due to its lack of high reliability in gold wire bonding properties (although it has been used in some low-end consumer products). On the other hand, ENEG shares the high production cost and presents complex challenges in terms of the manufacturing process, similar to electroplated nickel-gold.

ENEPIG was initially introduced in the late 1990s, its market acceptance was delayed until around the year 2000 due to fluctuations in palladium metal prices (which were inflated to unreasonable levels around 2000). However, ENEPIG can meet the requirements of many new packaging applications, providing reliable performance and conform to lead-free/ROHS requirements, with a recent strong surge in market demand.

In addition to the advantages in packaging reliability, the cost of ENEPIG is another benefit. With the recent rise in gold prices surpassing US$800/oz, it becomes challenging to control costs for electronic products requiring thick gold plating. The price of palladium (US$300/oz), relative to gold, is less than half, making palladium a cost-effective alternative with surface-related advantages.

Comparison of Surface Treatments

Up to now, for printed circuit boards accommodating fine-pitch QFP/BGA components, there are primarily four lead-free surface treatments:

Immersion Tin (IT)

Immersion Silver (IAg)

Organic Solderability Preservatives (OSP)

Electroless Nickel Immersion Gold (ENIG)

The table below compares these four surface treatments with ENEPIG. Among these surface treatments, none can simultaneously meet all the requirements of lead-free assembly processes, especially when considering multiple reflow experiences, pre-assembly shelf life, and gold wire bonding experiences. In contrast, ENEPIG offers good shelf life, solder joint reliability, gold wire bonding capability, and can serve as a touch button surface, providing surface-related advantages. Moreover, in the final gold replacement deposition reaction, the chemical palladium layer in ENEPIG works to protect the nickel layer, avoiding excessive corrosion during gold replacement.

(Table 1 – Comparison_of_Different_Surface_Treatment_Performances)

What Are Advantages of ENEPIG?

ENEPIG has several crucial advantages, demonstrating reliable solderability and gold wire bonding concurrently. The key benefits are outlined as follows:

  • Prevention of “Black Nickel Problem” – The absence of gold replacement attacking nickel on the surface prevents interfacial corrosion.
  • The chemical palladium layer acts as a barrier, preventing copper from diffusing to the surface, ensuring satisfactory solderability.
  • Palladium layer enable to completely dissolves in the solder, preventing the exposure of a high-phosphorus layer at the alloy interface. After the dissolution of the chemical palladium layer, the chemical nickel layer is revealed, forming a satisfactory nickel-tin alloy.
  • Capability to Withstand Multiple Lead-Free Reflow Cycles
  • Excellent Gold Wire Bonding Properties

These advantages make ENEPIG a preferred choice in various applications, ensuring reliable performance in both soldering and wire bonding processes while offering cost efficiency. As a one-stop PCB supplier in Asia, Best Technology possesses advanced technology and high-tech manufacturing equipment that can meet the “multi-variety, small volume, high quality, strong capability, short delivery” requirements. Welcome to contact us if you are going to find a reliable circuit board manufacturer.

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How Can I Reduce and Optimize the Cost of My PCB in A Best Way? – Series 2

Saturday, October 28th, 2023

At our latest blog, may the readers have understood the factors that will affect the PCB price, or maybe one of your have put it into practice that get a price lower than your budget. However, people are always not satisfied by the existing situation. If this is bother you as well, keep reading since this time we are going to sharing some useful tips that enable to optimize your PCB price until to the best.

  • Reduce board complexity

It can be said that try to simplest your design/layout and make it easy to fabricate is the simplest way to reduce your PCB cost. The more complex and irregular the forms, the higher the cost. Just remember: for every circuit board, no need to maintain a fancy diagram to demonstrate its excellence, perform functionality correctly is enough.

  • Design it in right size and thickness

Design your board in right size doesn’t means make it smaller as possible. You must know, if your design is complex and layouts are density, that means maker need to spend more time to assemble them. Highly compact sizes are always expensive, don’t skimp when it counts. Otherwise, more money will be spent to afford what you saved.

And in theory, the more layers and thickness the board, the more cost that manufacturer spend. Numerous layers in the PCB will have an influence for holes and diameters. It is recommended that if thinner thickness is enough, then just do it. 

  • Shapes, holes and rings should be regularly

Normally, keep the PCB as square or rectangular shapes is cheaper than irregular shapes like pentagon.  And large holes and rings enable to smooth the production run and easy to create. For smaller holes and rings means the driller must be smaller and delicate control.

  • Consider volume and choose manufacturer

In our last blog, we emphasize manufacturers will set a minimum order quantity (MOQ), it is common in this industry. So, consider your volume and check multiple quantities before ordering can help to recognize which one is the most cost-effective.

During the evaluation period, talk to your suppliers as soon as possible, knowing more about the material specifications, technical and PCB tolerances. A wrong choice will lead to much time waste and some unnecessary cost. This is we call “trial and error cost”. Try to make all things are clear and correct before production.

  • Pick the best vias

There are totally three types of vias in PCB: though-hole, blind, buried. The through hole can be passed through the whole board, while blind vias is created from top or bottom side to the middle of the board without through to bottom or top side. Buried vias, just as its names, it is buried inside the boards and we can’t see it by naked eyes.

Obviously, through hole is cost performance than other two vias, try to use more instead of blind or buried vias enable to decrease your cost. In additionally, blind and buried vias are always necessary in HDI PCB and RF board, otherwise, you don’t usually use them.

  • Make sure all SMT components on the one side

Trying to make all the surface mounted (SMT) components on the one side of circuit board if possible. In this way, assembler can finish the SMT process in one-time, so that can save much manufacturing time and cost. But if the components are distributed on both sides, it is needed to assemble two times, that is top side first – bottom side second (or sometimes bottom first).

  • Select easily replaceable component parts

It is assumed that one of part on your circuit becomes obsolete, then you must search for replaceable part or update your design if you would like to continuedly use this board. As an extensive experienced PCB manufacturer, we strongly recommend that select components that has standard dimension, so that it is easy to match alternative one.

In addition, visit some manufacturer’s website carefully to see if any components are marked as “obsolete” or “not recommended for new designs” before finishing your design. This enables to avoid secondary update.

  • Follow manufacturer’s PCB fabricate standards

Understand and follow manufacturer’s fabricate standards can keep your unit PCB price in a relative lower cost. When designing a new project, please make sure to following below tips.

  1. Use standard stack-up with standard materials.
  2. Design 2-4 layers PCB if possible.
  3. Keep your minimum line width and spacing within the standard spacing.
  4. Avoid adding extra special requirements as much as possible.
  • Use SMT components as possible

Choose surface mounted (SMT) components instead of through hole (THT) component whenever possible. SMT and THT are almost treated as separated manufacturing processes. Hence, if all the THT components can be replaced by mounted parts, the THT process will be eliminated completely. It is not only decreasing the manufacturing cost, but also reducing delivery time. Of course, it is not always possible, but it’s worth trying.  

Whatever decisions you make, the best solution is to consult and discuss with your suppliers. They be always to give you the best one that can save your money and meet your requirements as well. Meanwhile, if you don’t believe the suppliers, you are welcome to reach us. We promise that we can give you a most favorable price and high-quality product.

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