The Top PCB Assembly Defects and How to Fix Them

September 6, 2021
PCB assembly defects and solutions

To achieve a fully functional printed circuit board (PCB) product within a short timeframe, assembly teams must coordinate with quality assurance and design experts. This is why many teams bring our experts early on in the PCB design phase.

At Circuits Central, our Toronto-based PCB assembly team has spent many years correcting others’ mistakes in assembly projects. We can help pinpoint the common defects that we find in PCB assembly.

For larger project runs, PCB assembly defects can cause significant project problems in three areas:

Time to Market

Assembly defects will impact your time to market. It will take time to correct any assembly issues, as entire teams may be needed to resolve the issue.


Any delays will result in increased project costs, and these defects might cause the project to overrun the budget.

Performance Failure

If the defective PCB has already made its way to market, it may cause performance failure. Failures can impact the company’s brand reputation and may require the company to recall products to be reworked, which adds time and expense to the project.

To avoid these issues from damaging your company and causing long-standing project management problems, ensure that your team knows the most common PCB assembly defects and how to mitigate them.

We can help guide you in this area. Here’s an overview of the most common PCB assembly defects.

Incorrect BOM

The BOM (bill of materials) must be precise to prevent delays in the assembly process. Sometimes, the BOM includes outdated information or part numbers that don’t match the requested part. In some cases, the part ordered is too large for the PCB. These errors might only be corrected when the part is shipped. So, teams should ensure that all information on the BOM is accurate before moving forward.

Design for Manufacturability Errors

Design for manufacturability (DOF) is a critical element in designing printed circuit boards. Often, companies will make a mistake in the placement of components. The components might be too close to each other. Without focusing on accurate spacing, your team may discover they cannot automate the manufacturing process effectively. Therefore, your manufacturing team will likely face several challenges using pick and place machines.

Soldering Issues

The placement of the solder on the PCB should ensure structural support for the components. For example, companies using wave soldering should ensure they rotate parts to enter the perpendicular wave.

Placing taller parts after shorter parts during the wave-soldering process might also create a shadowing effect that reduces the tensile strength of the solder joints on the pins. Further soldering-related issues include:


During the manufacturing process, work teams may apply uneven heat during reflow, and the component may stand up on one end rather than having both ends soldered down. This issue is referred to as “tombstoning” and may result from different trace widths coming from two parts, which means the widest trace then acts as a heat sink.

Ensuring that heat is applied evenly throughout the soldering process is the best way to avoid tombstoning and all associated component placement problems.

Missing Solder Masks

In some smaller PCB design projects, the team may not use a solder mask due to a potential lack of space. This lack of a solder mask can lead to solder bridges forming when the team attaches the component to the PCB during assembly. A qualified Toronto-based PCB assembly team can minimize this issue and add solder masks to all small PCB surfaces.

Not Considering Test Processes

Testing procedures help ensure that all pins on the PCB have the requisite strength and connectivity. Therefore, teams must consider the testing processes when designing the PCB, and so a test point has to be placed for each net on the board and in a location where the probes for the test fixtures have clear access without hitting other components.

Make testing a focal point of the design phase by including a testing file that details the location of each test point on the board, alongside all other manufacturing data.

Giving Limited Areas for Repair Access

Repair access is a vital consideration when designing PCBs. The design goal should be to allow seamless PCB repair or upgrades in the future.

Without sufficient space between the components, teams cannot effectively repair the system or build upon the parts. This issue can add time to any required upgrades and risk damaging PCB components while the technicians make changes.

Choosing a Qualified Assembly Team is the Best Way to Eliminate Mistakes

To avoid each of the mistakes we highlighted in this post, ensure that you select a qualified assembly team with decades of experience. The right company can deliver precise designs for a seamless manufacturing phase.

Your specialist should have expertise in:

Design for Manufacturing

The company you work with should be able to review your PCB for design for manufacturing issues. This process involves analyzing the PCB and all parts for compatibility, then considering the board size and the soldering process to ensure complete structural integrity at each manufacturing stage.

Component Analysis

Comprehensive component analysis is another critical element when working with a PCB assembly company. The company should review the power demands of each part and their placement to ensure, for example, effective heat management. Component experts also know the marketplace and will help you find replacements for PCB parts that might be difficult to source or are otherwise unavailable.

Final Inspection of the Finished Product

Before manufacturing the PCB in high volumes, the design should undergo inspection through a qualified PCB assembly expert. The company’s team will use systems such as automated optical inspection, which involves using cameras to detect catastrophic structural failures. The camera will check for elements such as component placement, circuit shorts, and a missing solder. By the end of this in-depth analysis, you will have an error-free PCB ready for the market.

Turn to Circuits Central for PCB Assembly in Toronto

Our experts have decades of experience in PCB assembly and work with companies in Toronto and the surrounding areas to ensure their designs are flawless and ready for the market. To discover more about our full range of prototyping and assembly services, call us today.

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