6 ways to reduce the defect rate of automotive PCB
The automotive electronics market is the third largest application area for PCBs after computers and communications. As automobiles have evolved from traditional mechanical products into high-tech products that are intelligent, informatized, and mechatronics, electronic technology has been widely used in automobiles, both in engine systems and chassis systems. Safety systems, information systems, and in-vehicle environmental systems all use electronic products without exception. The automobile market has clearly become another bright spot in the electronic consumer market. The development of automotive electronics has naturally driven the development of automotive PCBs.
Among the key applications of PCBs today, automotive PCBs occupy an important position. However, due to the special working environment, safety and high current requirements of the automobile, it has higher requirements on PCB reliability and environmental adaptability, and the types of PCB technology involved are also wide. This is a PCB company. Challenges; for manufacturers who want to explore the automotive PCB market, more understanding and analysis of the new market is needed.
Automotive PCBs place special emphasis on high reliability and low DPPM. So, does our company have accumulated technology and experience in high-reliability manufacturing? Is it consistent with future product development? Is it good in process control? According to the requirements of TS16949? Have you achieved a low DPPM? These should be carefully evaluated. If you blindly enter this tempting cake, it will hurt the company itself.
The following is a representative part of the professional production of automotive PCB companies in the testing process, some special practices are provided to the majority of PCB colleagues for reference:
1, the second test method
Some PCB manufacturers have adopted the “secondary test method” to improve the rate of defects found in the first high-voltage electrical breakdown.
2, bad board foolproof test system
More and more PCB manufacturers have installed “good board marking system” and “bad board error prevention box” in the light board testing machine to effectively avoid human error. The good board marking system identifies the tested PASS board for the test machine, which can effectively prevent the tested board or bad board from flowing to the customer. The bad board error prevention box is the signal that the test system outputs the box opening when the PASS board is tested during the test; otherwise, when the bad board is tested, the box is closed, allowing the operator to correctly place the tested circuit board.
3. Establish a PPm quality system
At present, PPm (Partspermillion, defect rate of parts per million) quality system has been widely used in PCB manufacturers. Among the many customers of our company, the application and achievements of HitachiChemICal in Singapore are the most worthy of reference. More than 20 people in the factory are responsible for the statistical analysis of online PCB quality abnormalities and abnormal PCB quality returns. Using the SPC production process statistical analysis method, each piece of bad board and each piece of defective board returned are classified and statistically analyzed, and combined with auxiliary tools such as micro-slices to analyze which manufacturing process produces bad and defective boards. According to the statistical data results, the problem occurred in the process is purposefully solved.
4, comparative test method
Some customers use different brands of different types of PCBs for comparative testing, and track the PPm of the corresponding batches to understand the performance of the two test machines, so as to select a better performance test machine to test the automotive PCB.
5, improve test parameters
Select higher test parameters to rigorously detect such PCBs. Because if you choose a higher voltage and threshold, increase the number of high-voltage read leakage, you can increase the detection rate of PCB defective boards. For example, a large Taiwan-funded PCB company in Suzhou uses 300V, 30M, and 20 ohms to test automotive PCBs.
6, regular calibration test machine parameters
After the test machine is operated for a long time, the relevant test parameters such as internal resistance will be biased. Therefore, the machine parameters need to be adjusted regularly to ensure the accuracy of the test parameters. Test equipment In a large part of large PCB companies, the whole machine maintenance and adjustment of internal performance parameters are performed for half a year or one year. The pursuit of "zero defect" automotive PCB has been the direction of the majority of PCB people, but subject to various limitations of process equipment, raw materials, etc., the PCB world top 100 companies are still constantly exploring ways to reduce PPm.
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