Method of optimizing the defect rate of PCB for automotive
Among the key application objects of PCBs today, PCBs for automobiles occupies an important position. PCB copy board, but due to the special working environment, safety and high current requirements of the car, it has higher requirements on the reliability and environmental adaptability of the PCB, and the types of PCB technology involved are also wide, which is for PCB companies , Is a challenge; and for manufacturers who want to open up the automotive PCB market, they need to do more understanding and analysis of this new market. Automotive PCBs particularly emphasize high reliability and low DPPM. So, does our company have the accumulation of technology and experience in high-reliability manufacturing? Is it consistent with the future product development direction? In terms of process control, is it possible to follow the requirements of TS16949 well? Has a low DPPM been achieved? All these need to be carefully evaluated. Just seeing this attractive piece of cake and entering blindly will bring harm to the company itself. The following are some of the special practices in the testing process of some representative manufacturers of PCBs for automobiles for reference to the majority of PCB colleagues: 1. Secondary testing method Some PCB manufacturers adopt the 'secondary testing method' to improve the search The first high-voltage electrical breakdown rate of defective boards. 2. Bad board foolproof test system More and more PCB manufacturers have installed 'good board marking system' and 'bad board error proof box' on the bare board tester to effectively avoid human leakage. The good board marking system marks the tested PASS boards for the testing machine, which can effectively prevent the tested boards or bad boards from flowing into the hands of customers. The bad board error-proof box means that during the test, when the PASS board is tested, the test system outputs the signal that the box is opened; on the contrary, when the bad board is tested, the box is closed to allow the operator to correctly place the tested circuit board. 3. Establishing the PPm quality system At present, the PPm (Partspermillion, parts per million defect rate) quality system has begun to be widely used in PCB manufacturers. Among the many customers of our company, HitachiChemICal in Singapore is the most worthy of reference in its application and results. There are more than 20 people in this factory who are responsible for the statistical analysis of online PCB quality abnormalities and PCB quality abnormal returns. Using the statistical analysis method of the SPC production process, each broken board and each returned defective board are classified and statistically analyzed, and combined with auxiliary tools such as microsectioning to analyze in which production process the broken and defective boards are produced. According to the statistical data results, we can solve the problems in the process purposefully. 4. Comparative testing method Some customers use two different brands of PCB models for comparative testing in different batches of PCBs, and track the PPm of the corresponding batches, so as to understand the performance of the two testing machines, so as to choose the better performance testing machine Test PCB for automotive. 5. Improve test parameters. Choose higher test parameters to strictly detect such PCBs. PCBA OEM foundry materials because if you choose higher voltage and threshold, increase the number of high-voltage read leakage, which can improve 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.