DFM for PCBA – 40+ Improvements

Printed Circuit Board Assemblies (or PCBAs) are a critical component for electronic products of all kinds as they’re home to many of the electronic components that, simply put, allow the product to operate. Manufacturing and assembling them is either done by hand or automated machinery, and it’s a fairly intricate and complex process because of the different parts being soldered onto the board. That’s why DFM for PCBA, which has the goal of simplifying the manufacturing and assembly process of the PCBA, is an attractive proposition for importers, as it provides desirable benefits from this complex process such as lower production costs and better product quality.

What’s a PCBA?

A PCB is a printed circuit board that conducts signals and holds various components that will be soldered onto it. Once the components have been attached it is known as a PCBA, or printed circuit board assembly, and will look something like this example:

PCBAs can be found in almost any electronic product you can think of, such as computers, consumer electronics, automobiles, industrial machinery, and many more.

Why a failed PCBA is so damaging…

If a PCB fails, perhaps due to a quality issue, for example, it’s likely to result in a product breaking down or failing to turn on. In the case of many products that use PCBAs a failure like this is a worst-case scenario. For instance, let’s imagine that failure occurs in an automobile stopped to fill up with gas in the middle of a long journey…or, how about a laptop that is ‘dead’ and won’t turn on moments before the big presentation starts?

There are many reasons why a PCBA may fail, such as:

• A bad design of the circuit board itself
• Soldering inconsistencies
• Component failures or misalignments
• …and more

Following a DFM for PCBA approach will help streamline the design, manufacturing, and assembly of the board reducing overall costs and reduce quality risks resulting in these unwanted situations.

Areas where DFM for PCBA can provide improvements

There are 3 different areas, in order, where Design for Manufacturing, one of the most popular DfX approaches, can help improve PCBs and leave you with a superior PCBA. Let’s go through each and the 40+ improvements belonging to them…

1: PCB Design Improvements

DFM for PCBA can help improve the layout of the PCB, for instance, and this must be decided before the PCBA can be fabricated.

1. Using surface mount technology (SMT) components instead of through-hole components. This provides great accuracy and speed of component placement as well as providing a smaller footprint due to compact component design.
2. Grouping components by function to minimize the number of assembly steps. This can significantly reduce assembly time, decrease the likelihood of errors, and improve overall product reliability.
3. Reducing the number of manual assembly steps in PCBA through DFMA can improve production efficiency, reduce the risk of errors, and lower labor costs, resulting in an overall increase in product quality and profitability and reduced cost.
4. Minimizing the number of unique components can lead to lower material costs, simplify procurement and inventory management, reduce assembly time, and enhance product reliability by reducing the risk of component compatibility issues.
5. Minimizing the number of PCB layers to reduce manufacturing complexity and keeping the cost down.
6. Using surface mount pads instead of through-hole pads will result in reduced assembly time, lower material costs, improved signal integrity, and increased component density, resulting in a more compact design and enhanced product performance.
7. Designing for automatic optical inspection (AOI) and in-circuit testing (ICT) will improve the manufacturing yield, increase the reliability of the product, reduce rework, and lower the cost of quality control.
8. Using solder paste stencils to improve solder joint quality can improve the consistency and quality of solder joints, reduce the likelihood of rework, minimize material waste, and decrease assembly time.
9. Designing for wave soldering to reduce assembly time.
10. Using standard components to reduce costs and simplify sourcing, can improve inventory management, improve supply chain reliability, and reduce lead times.
11. Using a conformal coating to protect against moisture and other environmental factors.
12. Designing for pick-and-place machines to improve assembly accuracy, increase manufacturing efficiency, reduce assembly time, minimize the likelihood of errors, and enhance product quality, resulting in a more reliable and cost-effective manufacturing process.
13. Using common package sizes to improve sourcing and reduce costs, it also offers advantages such as availability, standardization, compatibility, cost savings, and design flexibility, leading to a more efficient, reliable, and cost-effective manufacturing process with a higher-quality product.
14. Using selective soldering allows for targeted heating of only the areas that require soldering, reducing the thermal stress on components and minimizing the risk of damage, which results in a more reliable product with a longer lifespan.
15. Using ESD protection to protect components such as diodes and varistors helps prevent damage to sensitive electronic components from electrostatic discharge, improving the reliability of the product and reducing the likelihood of failures due to ESD events.
16. Minimizing the use of vias to improve manufacturability.
17. Panelization involves placing multiple copies of the same PCB design onto a single panel, which can improve assembly efficiency by allowing multiple boards to be assembled simultaneously, reducing handling time, and increasing the number of boards that can be assembled in a single run.
18. Using test points, which are small pads on a printed circuit board that enable access to specific nodes in the circuit, allowing for easy and efficient testing and debugging during the manufacturing process and in the field.
19. Designing for high-speed signals to minimize signal integrity issues. This involves careful consideration of trace routing, termination, and impedance matching, as well as the use of high-quality materials and controlled impedance PCB manufacturing, to minimize signal integrity issues such as reflections, crosstalk, and signal attenuation.
20. Using pre-assembled components, such as surface mount technology (SMT) modules, can significantly reduce assembly time and increase manufacturing efficiency while minimizing the risk of errors or defects during the assembly process.

2: PCB Fabrication Improvements

During fabrication the circuit patterns you require for your product are etched onto a copper sheet and laminated onto a conductive substrate, this provides the basis for your components to be soldered onto in the correct positions.

1. Using snap-fit or press-fit assembly instead of adhesives or screws.
2. Simplifying the PCB layout to minimize wiring and routing, which results in fewer assembly errors, shorter assembly time, and lower production costs.
3. Minimizing the number of fasteners and using self-tapping screws instead if snap-fit assembly is not possible.
4. Using conformal coating application to reduce cost and improve quality.
5. Using ground planes to improve signal integrity and reduce EMI. These large areas of copper connected to the ground plane also provide a low-impedance return path for signals, reduce ground loops, and improve signal integrity by minimizing EMI, crosstalk, and other noise issues.
6. Using thermal reliefs to improve solderability, these are copper pads on PCBs with partial copper coverage, allowing easier and more consistent soldering, as they reduce the amount of heat required to melt the solder and prevent the solder from flowing into unwanted areas. This improves reliability and reduces the risk of errors during assembly.
7. Using proper silkscreen labeling to improve assembly and testing, by providing clear identification of components, test points, and other critical information, thus improving testing and debugging capabilities.
8. Using proper board edge clearance to avoid ESD damage while handling.
9. Using proper standoff heights to improve assembly and reliability, helps to prevent short circuits or other electrical issues that can arise from components being too close together or improperly spaced.
10. Using proper ESD grounding to avoid damage to components. Proper ESD grounding is important to prevent electrostatic discharge damage to sensitive components during manufacturing and handling, which can lead to reliability issues or even complete failure of the product
11. Using proper board thickness to avoid warping and improve reliability. If the board thickness is too thin, it could bend under a critical component with multiple solder joints causing de-soldering and product failure.
12. Using proper routing techniques to minimize signal distortion and EMI. 
13. Using proper component placement to avoid assembly errors. This is best achieved through SMT machines which are highly automated.
14. Using proper fiducial placement to improve the accuracy of pick-and-place machines. Proper fiducial placement involves placing fiducial marks on the PCB design in locations that will aid pick-and-place machines in accurately placing components, thereby improving the overall accuracy and speed of the assembly process.
15. Using proper grounding techniques to reduce noise and improve performance.

3: Assembly Improvements

Finally, the PCB has various components added to it either by hand or by machine. These could be microprocessors, switches, resistors, fans, etc, which are soldered onto the PCB in a circuit and, after testing is finalized, you’re left with a functioning PCBA.

1. Designing for reworkability to facilitate repairs and upgrades means designing the PCBA in a way that enables efficient and effective repairs or upgrades to be made when necessary, without causing damage to the board or other components.
2. Using automated inspection to reduce errors and improve quality. Using automated inspection techniques, such as Automated Optical Inspection (AOI) and X-ray inspection, can significantly reduce human errors in PCBA manufacturing and improve product quality.
3. Designing for automated depanelization to improve yield and reduce assembly time which involves designing the PCB in a way that allows for efficient separation of individual boards after assembly, this can improve yield and reduce assembly time by eliminating the need for manual depanelization, which is time-consuming and can be error-prone.
4. Using proper component orientation to avoid assembly errors. Having the correct orientation avoids assembly errors because it ensures that components are inserted in the correct position and direction, preventing polarity reversal or incorrect orientation which can lead to damaged components, short circuits, or other electrical problems.
5. Designing for automated AOI and ICT to improve quality and reduce costs. Automated AOI (Automated Optical Inspection) and ICT (In-Circuit Test) can improve quality by detecting defects early in the production process, and reduce costs by eliminating the need for manual inspection and testing.
6. Using proper lead-free soldering techniques to improve reliability and compliance.
7. Using proper component spacing to improve assembly yield. This is important for several reasons. Firstly, it helps to ensure that components are not damaged during the assembly process. Secondly, it can help to prevent bridging between adjacent components during the soldering process. Additionally, proper component spacing can help to improve the accuracy of pick-and-place machines and reduce the likelihood of assembly errors, which can ultimately improve assembly yield.
8. Using proper component labeling to improve assembly accuracy. Correct and accurate component labeling helps identify the components and their placement locations on the PCB which reduces the likelihood of incorrect component placement and improves the overall accuracy and yield. This is also important with the use of AOI and ICT which checks and verifies the correct components are being picked.
9. Using proper tooling to improve assembly consistency and quality ensures that the assembly process is repeatable, consistent, and accurate, resulting in improved quality and reduced variability.
10. Using proper soldering techniques to improve solder joint quality. This gives an improved solder joint quality by ensuring that the solder flows evenly and completely, creating a strong bond between the component and the PCB. Overall, it reduces the risk of solder bridges, cold joints, and other defects that can compromise the performance and reliability of the PCB.
11. Using proper depanelization techniques to avoid damage to components. Ensuring boards are separated in a way that minimizes stress on the components and the PCB will eliminate cracking, delamination, or other types of damage to the PCB or components, which can lead to functional failures or reduced reliability.
12. Using proper handling techniques to avoid damage to components. Many electronic components are sensitive to physical stress, heat, electrostatic discharge (ESD), and moisture, which can cause permanent damage or degrade their performance. Improper handling can result in defects, malfunctions, and failures of the final product. By using proper handling techniques, the risk of damage or defects can be minimized, ensuring high-quality and reliable electronic products.

Conclusion

The same as for plastic injection molded parts and die cast parts, following a DFM for PCBA approach can result in lower costs and improved quality if you implement some of these improvements successfully…two attractive benefits for manufacturers of electronic products!

If you have any questions about DFM for PCBA, or anything else related to developing and manufacturing your products, let us know as we’re happy to answer them.