Have you been in a situation where the results that you were getting from testing a circuit board were not what you were expecting? You knew that powering up and testing a new PCB design would result in some surprises, that’s what debug is for after all. The problem was that the results you were getting were way off, to the point where you couldn’t even perform the testing that needed to be done.
Finally, you realized that you were dealing with some sort of intermittent short—maybe there was some solder bridging or unintended slivers of copper somewhere. Whatever the problem was, you’ve just spent a lot of time that you can never get back only to find out that the issue wasn’t with your design, but related to the manufacturing.
Problems like this can often be tracked back to quality issues in PCB manufacturing. From fabrication to assembly, there are a lot of things that can happen to the circuit board, and choosing the right contract manufacturer can help to eliminate these issues. A good CM will have the systems and procedures in place to ensure the best quality assembly for your design. Here are some of the PCB quality issues that can happen during manufacturing, and how a good CM can prevent them.
Many common PCB quality issues can be prevented by working a CM that has adequate processes and procedures in place.
PCB Quality Issues That Can Cause Problems in Your Circuit Boards
There are many quality problems that can manifest themselves in a circuit board, here are a few you may have experienced:
- Unapproved part substitutions: It may have happened that a contract manufacturer substituted a different part into your design without the proper notification or approval from you. As long as the substituted part works, this can go unnoticed. If it doesn’t, however, you may see differences in device speed, timing, and value tolerances that can have unpredictable effects on the performance of the PCB. Tracking down these kinds of problems can be difficult and correcting them can cost time and money.
- Solder defects: Another common issue is the quality of the solder joints on the finished PCBA. This is usually due to the more complex component package types, but some CMs simply do not control and monitor their soldering processes as they should. This problem is especially painful for you to experience because it should be one of the main focuses of any CM’s quality testing and inspection processes.
- Neglecting customer-specific requirements: There may have been a time when you’ve submitted specific build instructions to your CM. These could include environmental compliance, packaging, or programming. Having your requirements be ignored can be a huge pain point when you discover that thousands of dollars worth of the product have been delayed or stopped due to a minor and preventable paperwork error.
- PCBA integration into system assemblies: When the assembled PCB is sent to a company that specializes in building system enclosures, the proper handling techniques for sensitive electronics are not always followed. In attempting to integrate the PCBA with the mechanical enclosure or other system assemblies, functional problems in the board may be introduced. These errors are often tied to the entire system assembly and can’t be diagnosed by just sending the failed board back to the CM.
- Cables and connectors: Mechanical interconnects between boards and other system components are susceptible to intermittent failures. This could be due to incorrectly built or incorrectly installed cables. These types of failures are difficult to track down.
- Mechanical assembly: Many mechanical components are not able to be checked properly with standard electrical test processes. Problems commonly encountered include mechanical components like heatsinks, faceplates, standoffs, and connectors that have been installed incorrectly and escape detection with standard test and inspection processes.
Problems like these will cause you time and money to find, diagnose, and correct. Fortunately, the right CM will have processes in place that will guard against these kinds of problems, as well as thoroughly test to make sure everything on your board is correct.
The Processes and Standards a Good CM Should Have in Place
To ensure that your printed circuit board is assembled with the highest level of quality, you should choose a contract manufacturer that has the following:
- Component testing: Your CM should have a thoroughly trained technical staff that is experienced in working with and testing the functionality of components. They should have documented processes in place that specify when and how component substitutions will take place and what their procedure is for working with you for notification and approval.
- State-of-the-art quality controls for soldering: Testing should occur before and after this critical step in PCB assembly. This includes automated optical testing and electrical testing done by certified inspectors.
- Engineering expertise: A dedicated engineering staff should review all of your specific needs and create a specific work plan that will accommodate any special build instructions that you might have. This includes the ability to fully document your work order and track all changes in a customer database so that you are fully apprised of all that is going on.
- The capability to perform a full “box build” of your entire system assembly: This gives your CM total control over all the assembly processes. This will prevent the typical problems, such as electrostatic discharge, moisture, and foreign objects and debris, that are associated with a multi-supplier assembly scenario.
- Partnerships with reliable vendors: This assures that system sub-assemblies, such as cables and harnesses, are built to the same exacting standards used by the CM.
- Fully documented test processes for all assembled components (electrical and mechanical): This ensures complete and total testing of the final PCBA.
Choose a CM That’s Committed to Quality
To avoid common PCB quality issues, work with a CM that has the processes and standards in place to ensure the highest quality build of your PCBA. From managing relationships with component manufacturers, to maintaining best practices for design reviews and engineering change requests, to assembly, soldering, testing, and inspection, a quality CM’s procedures will be reflective of the level of work they do, which ultimately impacts your project’s success.