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Printed Circuit Board

Printed Circuit Board Surface Finishes and Their Effects on Solderability and Reliability

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When designing a printed circuit board, selecting the right PCB surface finish is essential to ensure the reliable soldering of components. Different types of PCB surface finishes have different effects on solderability and reliability. The PCB designer and manufacturer should understand the different finishes available and how to use them to maximize the performance of the PCB. We will discuss here the different types of PCB surface finishes available, their effects on solderability and reliability, and tips for selecting the best finish for your project.

Choosing the best surface finish for your application requires careful consideration of several factors. By understanding the properties and benefits of different surface finishes and how they align with your specific needs, you can make a good decision.

The Different Types of PCB Surface Finishes

There are several types of surface finishes to choose from, each with its unique characteristics and benefits.

  1. HASL (Hot Air Solder Leveling): This is one of the oldest and most commonly used surface finishes. It involves applying a layer of molten solder to the surface of the PCB and then flattening it using a hot air leveling process. HASL provides a durable and cost-effective surface finish, but it may not be suitable for fine-pitch components. It has some disadvantages such as the formation of solder balls and their thickness, which can cause issues with fine-pitch components.
  2. ENIG (Electroless Nickel Immersion Gold): ENIG is a popular surface finish for high-density PCBs with fine-pitch components. It involves depositing a thin layer of nickel on the surface of the PCB, followed by a layer of gold. ENIG offers excellent corrosion resistance and solderability, but it is more expensive than other surface finishes.
  1. OSP (Organic Solderability Preservatives): OSP is a thin organic coating applied to the surface of the PCB to protect it from oxidation and other environmental factors. OSP is a cost-effective option in this case, but it may not be as durable as other surface finishes.
  2. Immersion Tin: This surface finish involves depositing a thin layer of tin onto the surface of the PCB. Immersion tin offers good solderability and can be an affordable option for certain applications. However, it may not be suitable for PCBs with high-temperature requirements.
  3. Immersion Silver: This surface finish involves depositing a thin layer of silver onto the surface of the PCB. Immersion silver offers excellent solderability and is a popular option for high-speed PCB designs. However, it can be more expensive than other surface finishes and may not be as durable in harsh environments.

Each type of PCB surface finish has its unique advantages and disadvantages. When selecting a surface finish for your PCB design, consider factors such as the type of PCB components, the operating environment, and the cost.

The Effect of Surface Finish on Solderability

The surface finish of a PCB can have a significant impact on the solderability of the components and the overall reliability of the board. In this section, we will take a closer look at how different surface finishes can affect the solderability of PCBs.

First, you must understand that the surface finish of a PCB refers to the thin layer of material that is applied to the copper pads on the board’s surface. This layer is essential because it protects the copper from oxidation, corrosion, and other forms of damage.

You would see that HASL leaves behind a thick layer of solder on the surface, which can be difficult for small components to bond with and can also lead to uneven solder joints. Moreover, the excess solder can also create short circuits and reduce the board’s overall reliability.

In contrast, the electroless nickel immersion gold (ENIG) surface finish has become increasingly popular in recent years due to its ability to provide excellent solderability and reliability. ENIG provides a flat surface for components to bond with. The gold layer is also non-corrosive and has a high resistance to wear and tear.

On the other hand, immersion silver offers good solderability and a relatively low cost compared to ENIG. However, silver is more prone to tarnishing and can cause problems with the board’s reliability over time.

The Effect of Surface Finish on Reliability

The choice of surface finish can significantly impact the longevity and overall performance of the PCB. The surface finish of a PC Board can affect its ability to resist corrosion. Certain surface finishes, such as gold or silver, provide excellent corrosion resistance, ensuring that the PCB remains protected even in harsh environments. On the other hand, some finishes like HASL are prone to corrosion, which can lead to the failure of the circuit board.

The surface finish can impact the electrical performance of the PCB. Some surface finishes have low electrical resistance, which can help to minim ize signal loss. Conversely, finishes that have higher electrical resistance can lead to signal distortion and reduced performance. So, you should consider the electrical requirements of your PCB when selecting a surface finish.

The surface finish can also impact the mechanical durability of the PCB. Certain finishes, such as immersion gold, provide a thin and uniform layer that is less likely to crack or peel during thermal cycling. Other finishes, like OSP, are more susceptible to wear and tear, which can lead to damage to the circuit board.

Overall, the choice of surface finish for your PCB can have a significant impact on its reliability and performance. By understanding the strengths and weaknesses of each type of finish, you can choose the right finish for your specific application and maximize the longevity and reliability of your circuit board.

How to Choose the Best Surface Finish for Your Application

Now that we have covered the different types of surface finishes and their properties, it’s time to discuss how to choose the best surface finish for your specific PCB application. Here are some factors to consider:

  1. Environment: The first thing to consider is the environment in which the PCB will be operating. If it has to work in a harsh or high-temperature environment, you may want to choose a surface finish that is more durable and resistant to corrosion, such as ENIG or OSP.
  2. 2. Cost: Different surface finishes have different costs, so you need to consider your budget in this case. HASL is the most affordable option, while gold finishes tend to be more expensive.
  3. Solderability: As discussed earlier, you should consider the solderability of the surface finish. Some finishes, such as OSP, require a longer preheat time, while others may require the use of special solder pastes or fluxes. Make sure the surface finish you choose is compatible with your soldering process.
  4. Compatibility with other materials: If you have to assemble the PCB with other components or materials, make sure that the surface finish is compatible with them. For example, some finishes may react negatively with certain solders or coatings.
  5. Electrical properties: Finally, you need to consider the electrical properties of the surface finish. Some finishes, such as gold or silver, offer better conductivity, while others may cause increased resistance.

Ultimately, the choice of surface finish will depend on your specific requirements. If you are unsure which finish is best for your project, you can consult with a professional PCB manufacturer who can guide you through his expert advice.

FAQs

What are Common PCB Surface Finishes?

Some popular surface finishes of printed circuit boards include HSL (Hot Air Solder Leveling), OSP (Electroless Nickel Immersion Gold), ENIG (Organic Solderability Preservatives), immersion silver, and immersion tin.

What Is The Benefit Of HASL?

HASL is one of the most popular surface finishes due to its versatility. HASL provides good solderability and is suitable for most applications.

What Is The Benefit Of Using ENIG For PCB?

ENIG is corrosion-resistant and provides a flat surface that is perfect for fine-pitch components.

What Is The Benefit Of Using Immersion Silver For PCB?

Immersion silver offers excellent conductivity and is ideal for RF applications.

Which PCB Surface Finish Is Cost-Effective?

HASL is the most affordable surface finish for printed circuit boards.

Final Thoughts

When designing a printed circuit board, one of the most important factors to consider is the selection of the right surface finish. This is because different surface finishes can significantly affect the solderability and reliability of the finished PCB.

Choosing the right surface finish for your PCB can have a significant impact on its solderability and function.  Some finishes, like ENIG, provide excellent solderability and are preferred for applications that require a high degree of reliability. Other finishes, like OSP, can be more difficult to solder and may require extra steps to ensure proper adhesion.

While there are several options available, ENIG has become a popular choice due to its excellent performance and long-term durability. Ultimately, it’s essential to consider your application’s specific requirements and choose a surface finish that meets those needs.

Would like to know more about the PCB surface finishes or pcb assembly? Write us at sales@pnconline.com

PCB Design Limitations beyond Borders

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The design of printed circuit boards is a complex and detailed process that must meet certain requirements to ensure optimal performance. One of the most important considerations when designing a Printed Circuit Board is edge clearance or the distance between a trace and the edge of the board. Unfortunately, in many cases, edge clearance may be too small to meet certain safety and performance standards. This can lead to problems with electromagnetic interference and other issues.

With the right edge clearance, you can ensure that components do not touch each other and cause short circuits. However, there may be times when you need to extend beyond the standard edge clearance limits to accommodate certain components. So, we want to explore different methods of extending past edge clearance, so that you can create a more functional and aesthetically pleasing design.

The Importance of Edge Clearance

Edge clearance is an important aspect of design. It is the distance between two traces on a circuit board and helps to ensure that the signals are isolated from each other, avoiding interference and crosstalk. Proper edge clearance also prevents shorts from occurring due to accidental contact between two components. Without proper edge clearance, the circuit board may not function correctly, or at all

Edge clearance plays an especially important role in high-speed and high-frequency designs, as it ensures that the traces are far enough apart that they don’t interfere with each other’s signals. Edge clearance also affects the signal integrity and the overall performance of the PC Board. Poorly designed edge clearance can cause signal degradation, data loss, and even the destruction of components.

In general, PCB designers should aim to have at least 6 mils or 0.006 inches of clearance between traces to avoid any potential issues. However, depending on the complexity of the design and the components, this value can be higher. It is also important to remember that edge clearance varies depending on the size of the trace, voltage levels, and other factors. Designers need to consider all of these factors when designing their PCBs to ensure that the edge clearance is adequate for the design.

Factors That Affect Edge Clearance

When it comes to designing a printed circuit board, different parameters can affect the edge clearance of the design. Some of the most important factors include:

  1. PCB Size: Edge clearance is directly proportional to the size of the PCB; the larger the PCB, the more distance between components and the edge of the board will be required. This is why it is important to carefully consider the size of the PCB before beginning the design process.
  2. Track Width: The width of any tracks on the PCB will also have an impact on the edge clearance. Tracks with larger widths will require more clearance space around them, so designers need to be mindful when choosing track widths in their designs.
  3. Components: The size and shape of the components can also have an impact on edge clearance. Larger components require more space around them, as well as additional spacing for any pins or connections that may protrude from the component body.
  4. Electrical Clearance: You must also consider the electrical clearance requirements. Adjacent components can affect the electrical signals, so designers must ensure that they maintain adequate spacing between components and the edge of the board.

Understanding and taking into account these factors is crucial when designing a PCB with proper edge clearance. By being aware of these considerations, engineers can make sure that their designs are safe and reliable, while also allowing them to extend past clearance if needed. Other than understanding the factors that affect edge clearance, there are several techniques and strategies that designers can use to increase their margins of safety. One such strategy is implementing guard rails along the edges of the PCB which prevent components from getting too close to the edges.

It’s also possible to use vias instead of traces when routing along the edges of the board since vias have greater electrical clearance than traces. Moreover, using smaller components and smaller track widths wherever possible can help free up some much-needed extra space along the edges.

Another way to increase the margins of safety is by making use of breakout boards whenever necessary. This will allow you to route complex circuits away from the main board, reducing clutter and giving you more room for edge clearance. With careful planning and attention to detail, you can easily extend the past edge clearance without compromising safety or reliability in your PCB design.

Some Important Design Rules

There are certain rules and regulations for designing printed circuit boards. There are many parameters in this regard that you have to follow. Hence, the clearance between different components has to be according to the design rules, such as:

  • The edge clearance in the case of resistors should be at least 05”.
  • The edge clearance in the case of connectors is possible through tab routing. Sometimes you can combine tab and scored routing. However, try to avoid edge connectors if the design allows you.
  • The edge clearance for capacitors should be less than 119”.

Placement of Drill Holes

  • You should also try to keep drill holes far from PCB edges. The drill holes near the edges can result in cracks in the board. The appropriate distance of drilled holes from the PCB edge can be 0.010”. This clearance applies to both un-plated and plated holes.
  • Moreover, the planes and copper traces’ distance from the board edge should be a minimum of 0.010”.
  • The distance of the traces from the mouse bite’s deepest edge should be at least 0.025”.
  • The distance of the components from the mouse bite’s deepest edge should be at least 0.075”.

The right distance between the edge and PCB elements helps manufacturers have flawless production.

Tips for Successfully Extending Past Edge Clearance

When designing a printed circuit board, it is important to ensure that there is enough clearance between components and the board edge. When extending past edge clearance, it is important to know how many extensions you need for the components to fit properly.

The amount of extension will depend on the size of the components, their placement relative to the edge, and any other constraints on the board. When possible, use larger pads and add a solder mask to the extended area to increase the chances of having enough clearance. Moreover, the length of any tracks and vias should be as short as possible to reduce their impact on the edge clearance.

To ensure the best results, use professional CAD software and its DRC tool to simulate the layout of your board before fabricating. This will help you to verify that all components have adequate clearance and that there are no overlapping traces. It is also important to measure the actual size of the components before laying them out to make sure they will fit properly.

When designing the board with extended clearance, the first step is to determine how much clearance is necessary. You can evaluate it by measuring the height and width of the components that will be on the board. The clearance should also take into account any extra space that assembly and rework may require.

After determining the clearance, it’s time to design the board. When laying out the board, you must ensure that any exposed edges have a minimum amount of clearance. To extend the edge clearance beyond the recommended minimum, use extended tracks. This will provide an additional amount of space between the edge of the board and the components.

When laying out the tracks, keep in mind that they must remain connected to each other. To ensure that all of the tracks are connected, you can use vias or micro vias. You can use Vias to connect different layers of a PCB, while micro vias can connect the same layer.

In the end, make sure to add a solder mask to any areas with an extended clearance. Solder mask is a protective coating that helps to prevent solder bridging and shorts between components. It also helps to protect against corrosion and improve electrical performance.

Wrap Up

Designing a printed circuit board is a complex process, as it requires precision and accuracy to create a successful product. When it comes to design, certain limitations should be considered. One of these is edge clearance, which limits how close components can be placed to the edges of the board. Fortunately, there are ways to extend past edge clearance, allowing for even more flexibility in PCB design.

Edge clearance plays an especially important role in high-speed and high-frequency designs, as it ensures that the traces are far enough apart that they don’t interfere with each other’s signals. Edge clearance also affects the signal integrity and the overall performance of the PCB. Poorly designed edge clearance can cause signal degradation, data loss, and even the destruction of the components.

Would like to know more about the Design Limitations or pcb assembly? Email us at sales@pnconline.com

Why printed circuit board manufacturers use plated slots ?

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Printed Circuit Board Plated Slots

Slots are holes, which are either plated or non- plated-through. So, plated slots are holes plated in copper. And we use them for electrical connections on the PCB. A through slot is the one that goes to the entire depth of the board, starting from one end to another. Whereas a PCB outline or edge also has plating called side plating.

printed circuit board manufacturers use plated slots for components packaging, however, non-plated slots are also in practice. But, PCB with multiple layers have only plated-through slots.

Why Prefer Plated Slots?

PCB assembly involves different designs and components, and you would often see round holes to accommodate the round components or square as well. A round hole suits a PCB with through-holes. However, certain components are compatible with the blade or rectangular leads, so the round or square holes are not ideal in that case, and this is where a plated slot works.

When the pin size becomes large, the rectangular connectors work with plated-through slots rather than round holes. Like, they are ideal for the DC Jacks. Though you can use the round holes for small connectors and rectangular pins, plated slots are better because they take less space on the PCB, unlike the round holes.

Difference between Plated And Non-Plated Slots

Plated slots have copper plating in the circuit layer, whereas it opens in the solder mask.
On the other hand, non-plated slots don’t have copper plating in the circuit layer, besides, it does not open in the solder mask.

Design of Plated Slots

There is a specific way to show plated holes on the Gerber, like:

    • You have to put the copper pads on the upper and lower solder mask.
    • Then you insert a milling slot in the mechanical layer.

Designers prefer a mechanical layer to put slots in the Gerber and it involves two possible options to do it.;

Use of Flashes Having the Right Size Slot

Drawing a slot with a 0.50 mm thick line, as it helps designers to check it visually to ensure that there is enough tolerance between copper and the PCB edge. Remember that a line’s center is considered the edge of the slot.

Then you have to join the slots with the PCB outline into the Gerber, and it should be parallel to the copper layer. However, the copper layer should also have a PC Board outline to stay on the safer side.
The mechanical layer in this case has different names, depending on the system. It also depends on milling as it should be there. However, you can use another layer in the absence of a mechanical layer. Use the README file to avoid any doubts regarding the right file.

Don’t always define slots in a legend or a copper layer because they could be misinterpreted. Show large slots in the legend or copper layer, however, the outline should be precise. Don’t forget to write the text SLOT in the center.

Creating a Drill File

You can also define the plated slots through drill files as it is a precise way, however not all CAD software allows this option. But, defining through the drill files involves the X and Y or the slot width and length, instead of a complete row of holes that overlap.

Understanding A Small Slot In The PCB

The size of the smallest slot varies, depending on the type of the PCB, like if it’s flex, rigid, or rigid-flex. The width of the smallest slot is 0.50 mm for a rigid and flex-rigid PCB, and the length is often 1.0 mm.

These sizes are so due to more thickness of the PCB, besides, the slots are created through the NC milling that is mechanical. As, the grooving cutter of NC is 0.50 mm and its length is twice the width, like 1.0 mm.

On the other hand, the thickness of the flex PCB is less, and you can make slots through a laser machine. Designers prefer the smallest slot because the bigger slot’s length becomes more which is twice its width.

Milling Of the Cutouts Or Slots

You have to use the round NC grooving bit for the milling of slots in the rigid PCB, and it’s just like the CNC machine. However, the inner corners of the slots are made round instead of sharp. Whereas the PCB edge is created to the center of the border.

Which Industries Can Use the Plated Slots?

Mostly the thick or multilayer PCBs have plated slots, and such boards are ideal for different industries, including aerospace, consumer electronics, computer, and telecommunications. As these slots don’t take much space, they are cost-effective in terms of making. A board with both plated slots and round slots is also ideal for multiple electrical connections.

Frequently Asked Questions

What Is A PCB?

PCB stands for a printed circuit board having different electrical components, holes, and other features. Various industries use PCB boards to provide the electrical signals to run different devices or electronics. A PCB board can be embedded, single or double-layered, or can have many layers like up to 60 plus.

What Is The Definition Of A Plated Slot?

A plated slot is a hole in the PCB with copper plating. It is not round, so it is ideal to accommodate the leads with rectangular pins. You can use such a slot for electrical connections and component packaging
The slot goes throughout the circuit board that’s why we call it a plated-through slot.

What Is Edge Plating?

If plating is done on the edges of a PCB, we call it edge plating. Besides, you can also call it the side plating of a circuit board. It goes from the upper layer to the lower layer of the PCB, extending to an edge of the perimeter.

Which Circuit Board Should Have Plated Slots?

Generally, the multilayered PCBs have slots with plating also known as plated-through slots. However, there are also non-plated slots, depending on the PCB design and its application.

Do I Need A Lot Of Space For Plated-Through Slots?

Plated slots are mostly rectangular, hence they don’t take much space on the PCB like the round slots. So, such slots are ideal when you run short of space on the PCB, and where you need to use the rectangular Jacks.

What is a Copper Layer?

PCB has different layers of which one is a lamination made of copper foil, and it is attached to the circuit board with some adhesive. The copper layer is essential for a two-sided PCB, including copper on both sides. But, PCB boards with more than 60 layers of copper are available by different companies.

What is Solder Mask Layer?

The green color on the circuit board is a solder mask and its surface is called the solder mask layer. The purpose of the solder mask is to cover the exposed copper to prevent users from the electric shock upon contact. Though it is mostly green, other colors are also available.

Final Thoughts

PCB manufacturers use plate slots for components packaging, however, the non-plated slots are also in practice. But, PCB with multiple layers has only the plated-through slots. Certain components are compatible with the blade or rectangular leads, so the round or square holes are not ideal in that case. This is where a plated slot works.

Plated slots have copper plating in the circuit layer, whereas it opens in the solder mask. Non-plated slots don’t have copper plating in the circuit layer, besides it does not open in the solder mask.

The size of the smallest slot varies, depending on the type of PCB, like if it’s flex, rigid, or rigid-flex. The width of the smallest slot is 0.50mm for rigid and rigid-flex PCB and the length is often 1.0 mm. Engineers use cad software to make Gerber files for different types of slots including plated through and non-plated through slots.

Would like to know best practices for Plates Slots or printed circuit board assembly? Email us at sales@pnconline.com

PCB assembly Pre-Reflow FAI

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First article inspection (FAI) prior to SMT assembly is a design verification methodology that provides a reported verification and validation of details of a product on the shopfloor per its manufacturing procedure and requirements. There are various ways to perform FAI, from both supplier’s and customer’s side, making it a very dynamic process. This means that each organization can tailor its FAI method to benefit itself and consequently, its customer, yet maintain rigid performance standards at the same time. FAI involves qualitative and quantitative measurement. FAI is also highly effective since it can potentially fulfill process validation requirements of quality management systems like ISO9001 or AS9100.

In the PCBA manufacturing industry, FAI can be effectively employed in validating materials for manufacture, underlying technologies, manufacturing processes used, packaging, and equipment. It can also be applied to a batch of a given sample-size from a mass-production instead of just the first sample, as the name might suggest. At PNC, strict adherence to our manufacturing standards helps in production with better yield but at the same time, facilitating dynamic validation techniques in our manufacturing process allows us to reduce lead time. The focus of FAI in PNC assembly lies in validating the pcb assembly before reflowing so that the SMT team can make necessary adjustments for the next batch, saving time and effort during rework. They are also responsible for validating the correct loading of the right component in its allotted slot per the assembly program. This extra step helps in validating the placements of the components and improves the turnout rate for a successful production.

All aspects of reflow also must be amenable to improve solder performance and the same translates to our guideline where only the most recent batch of solder paste (with most activity) is permitted for use, which is validated by FAI. Apart from pre-reflow FAI, post-reflow X-Ray also helps validate the solder performance based on the reflow profile which can then be adjusted accordingly so that all components are successfully soldered. This can be similarly implemented at the rest of the printed circuit board assembly stages as well up to testing. But there is a necessity to establish a constant groundwork or point of reference in such a dynamic process to give each validation at a particular stage, the perspective of what changes were made before. This is achieved by using a single piece of documentation used to validate at every stage, wherever applicable, and that document reports any changes made to the processes or product, to the next stage.

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PNC employs the use of AEGIS software to combine SMT assembly guidelines and inspection requirements into a single document (internally referred to as AEGIS). The AEGIS is used to report every single FAI validation to different stages of assembly. PNC’s FAI process for SMT starts with thorough solder paste FAI & its validation, which will be detailed in another post. For this post, let us consider pre-reflow FAI and highlight its validation process since it is the most crucial stage. The procedure is as follows:
1. The SMT team confirms the correct allocation of components as given in the assembly program. This is done by comparing each component with its description, measuring component value wherever applicable, and checking for physical marking on ICs. This helps in validating that the right component has been placed in its respective position on the board.
2. The next step involves checking for the polarity of components, wherever applicable. This is a two-step process. First, the supply angle of a component in the reel needs to be checked and second, the placement of that very component on the PCB needs to be verified.
3. Now, once the first board is assembled, the pcb assembly is put through FAI, where the placements of all components on the board are checked, any necessary placements that remain are placed manually and polarities of applicable components are checked and changed as per what is given in the AEGIS. The same changes are made in the assembly program to avoid the same occurrence in the rest of the batch. Components that are designated as DNP (Do Not Place) are also checked and finally, the solder paste information such as solder type, lot number, date of manufacture, and expiry are checked to ensure that the right solder paste has been used.
4. All these checks translate to notes, remarks, and checks on the AEGIS document, which can then be referred at later stages up to final inspection. If the job in consideration is a repeat job, it can be optimized to avoid any errors made in the first batch of production.
5. The board is then sent through reflow. Once reflowed, the board is extensively inspected under high magnification camera for quality of component placement, solder joints etc. yielded by SMT process.
6. Each section in the AEGIS is meant for FAI by a different team performing a different operation.

PNC has been able to reduce its lead time and increase customer satisfaction significantly and our personalized and successful FAI is a big factor contributing towards it. Further development to the FAI process is underway as much as it is needed to achieve better production yield over time for all the different types of PC Board assembly that are assembled at PNC.

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Ensuring a successful Turnkey PCB Assembly project

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There are many detailed factors involved when pursuing the right company for your electronic or PCB assembly needs. These factors can be broken down into two distinct areas, customer communication and supplier contract review. Either the customer or the supplier cannot afford time lost if there is a misunderstanding or lack of data to efficiently and effectively produce a quality product on time. Time spent up front makes for a smooth and efficient transition through the quoting and manufacturing process.

Customer communication

A majority of communications for a request for quote, RFQ’s, in today’s industry are via email. The email needs to contain the required data files and be clear and concise in regard to quantities and delivery dates, along with any details that are not stated on the fabrication/assembly drawings. Since we are talking about Printed Circuit Board Assembly Turnkey projects, let’s break this down further with the required data files for PCB and PCBA.

PCB data files:

1- Fab drawing with build details such as material type, thickness, Copper weight, Tg rating, IPC-A-600 Class, Stack-up, Drill Chart, LPI & silk screen color, Serialization, Panelization array, MIL Spec, final finish and type(RoHs/Non RoHs) etc.
2- Complete set of gerber files.
3- Drill files.
4- IPC-356 Netlist for electrical testing.
5- Read me file for additional information not stated in fabrication drawing or email.

PCB Assembly data files:

1- BOM with manufacturers part number/description and alternates if applicable or DNP’s.
2- Assembly drawing with build details, Solder paste requirements, torque specs, IPC-A-610 Class, DNP’s, serialization, etc.
3- Pick & Place file.
4- ICT or Probe testing if applicable.
5- Functional test procedure if applicable.
6- Read me file additional information not stated in fabrication drawing or email.
If all the required information and data files are complete, we have successfully met the first half of the RFQ process. With this in mind, it’s up to us to compile this information in our contract review process. Let’s take a look at what is processed on our end to complete the RFQ cycle.

Supplier Contract review

All incoming turnkey projects are given an internal number for uniqueness especially for part numbers that has been revised. They are stored in a secure file folder based on two groups of data. ITAR data is stored separately than non-ITAR data. Once the customers data is stored and secure, engineering is notified to start to contract review process for the PCB and PCBA data sets.

Contract review for PCB:

1- Gerber files are imported and overlaid into correct layer structure.
2- Drill files are imported and overlaid against the gerbers.
3- If there is no IPC-356 Net list file, we extract the net from the gerber.
4- The gerbers are ran through a design rule check for manufacturability.
5- Fab drawing is reviewed by engineering for manufacturing capability.
6- If any discrepancies are determined, customer is notified immediately, If no discrepancies, engineering hands off the internal contract review check sheet to customer service.

Contract review for PCB Assembly:

1- BOM is scrubbed to ensure all parts are identified by manufacturer and P/N.
2- BOM parts stock research from approved vendor list.
3- Assembly drawing reviewed by engineering for assembly capability.
4- Pick & Place file review.
5- Review for testing if applicable.
6- If any discrepancies are determined, customer is notified immediately, If no discrepancies, engineering notifies customer service.
7- Quoting team is notified to officially create the quote and send to customer.
Customer communication and supplier contract review is a relatively simple step in order to achieve and ensure a successful assembly turnkey project. Adhering to the steps above can make for a great partnership.