Printed circuit board (PCB) quality control is increasingly important. That’s particularly true with PCBs used in critical applications and industries, ranging from aerospace to health care. PCB manufacturers must find flaws before those components leave the factories and get installed in products. Here are some ways they can do that.
Tweak processes to allow test data collection
A good starting point to improve PCB quality is to gather test data that shows how and why the components are most likely to fail and when these problems are noticed. That gives companies a helpful baseline that guides improvement.
Dave Huntley is the director of business development at PDF Solutions. Manufacturers cannot count on repairing boards late in the process, he explained. “Mission-critical applications are now not allowing for end-of-line repair of boards,” Huntley said.
“Finding and isolating problems early in the process is critical to reduce scrap," he added. "Having assembly and consumable data that is stored and can be correlated to test data enables this.” Having the data offers multiple benefits. First, it helps manufacturers identify issues earlier, giving them time to fix them. Factory managers can start finding trends that allow them to take steps so flaws never appear or are greatly reduced.
However, factory leaders that commit to collecting better data should also realize they’ll need more time for testing overall. Huntley said. “In today’s PCB manufacturing lines, there is a lack of good rich parametric test data," he said. "For example, in-circuit testers (ICTs) are not logging most of the test data that they could. The reason is that it impacts test time significantly, which would create line bottlenecks.”
Investing in better training to ensure all testers follow the same processes may be required. As Huntley explained, “Also, in PCB end of line (EOL) testing, the testers are not sophisticated. There are wide variations across testers in measurement accuracy. This leads to increased scrap and poor quality of parts shipped.”
Look for opportunities to improve inspection methods
PCB companies should also review the technologies they use to inspect the products and see how they might get better results. One examination of the lighting used for machine-vision inspections of PCBs produced some useful outcomes. It showed that high-angle lighting was unsuitable for checking coated and highly reflective boards. That approach did not give the necessary contrast for scrutinizing features. However, using broad-spectrum lighting in a diffuse dome arrangement gave more-uniform illumination.
Investing in new software could also enhance PCB quality control. One new release from the Saki Corp. for X-ray inspection of PCBs claims to give a 50% reduction in PCB cycle time for people who use it. Norihiro Koike, the company’s president and CEO, said, “The 3Xi-M110 uses Saki’s proprietary Planar CT technology to detect solder joint defects and microstructure abnormalities in high-density printed circuit boards and does so with industry-leading accuracy.”
Another project in the pipeline uses augmented reality (AR) and artificial intelligence (AI) to compare a digital twin containing the PCB design file with the physical component in front of an inspector. Manufacturers often use digital twins to test the feasibility of products in the early stages of their development. However, this example for PCB testing shows they can assist later, too.
Maintain good communication and preparatory processes
Some aspects of PCB quality control happen before the bulk of activities occur in the factory. As a starting point, there must be ongoing communication between the client and the PCB manufacturer. Those exchanges will ensure everyone is on the same page and that the manufacturing partner understands and can fulfill the customer’s needs.
Another step that can help improve quality is running a manufacturing design (DFM) check. It pinpoints design errors at early stages, preventing them from becoming costly later. Examining details like the spacing between components and their polarity is best to do as early as possible and before production begins. Otherwise, the client is more likely to find mistakes in finished PCBs that could have been caught substantially earlier.
The DFM check concerns PCB topology problems that could cause manufacturing issues. Doing one before production starts keeps quality levels high while preventing cost overruns.
Make quality a priority throughout the company
Many team members may not initially realize that quality control is everyone’s collective responsibility, regardless of the specific role someone has. Decision-makers should strongly consider what’s within their power to influence at the company to help it have a quality-centered culture.
One of the most accessible avenues to pursue is arguably to have everyone with an applicable job get certified by the Institute of Printed Circuits (IPC). A 2019 survey from IPC indicated that 33% of the participating manufacturers expressed that their main challenge was hiring highly skilled soldering professionals.
In that case, a good workaround to improve quality may be to have internal programs where people gradually get the skills they’ll need to try for their IPC certifications. Quality then starts from and stays within the company, reducing the need to hire skilled people elsewhere.
A factory manager may also wish to post quality checklists at each station used for PCB assembly. People that have visual reminders of the proper steps to take are more likely to adopt good habits that will have ripple effects at the company.
Finally, the commitment to quality must occur with a top-down approach. Team members on the factory floor who see that supervisors and others in higher positions don’t seem to care about quality will have trouble taking it seriously, too.
PCB quality control requires an ongoing effort
It’s not enough to only focus on a single aspect of PCB quality control. Similarly, decision-makers cannot lead an all-out effort to improve PCB quality that only lasts for a couple of months. Setting metrics and checking them periodically helps verify if goals are being met and other progress is happening.
Making substantial improvements in quality means people must make lasting commitments to that effort and encourage others in the factory to do the same.
Emily Newton is a technical writer and the Editor-in-Chief of Revolutionized. She researches and writes about how technology is changing the industrial sector.