Method of Optimizing Defect Rate of Automotive PCB
In today's key application objects of PCB, PCB for automobile occupies an important position. However, due to the special working environment, safety and high current requirements of automobiles, PCB copying requires high reliability and environmental adaptability of PCBs, and involves a wide range of PCB technology types, which is a challenge for PCB enterprises; For manufacturers who want to expand the automotive PCB market, they need to do more understanding and analysis of the new market.
The PCB used in automobile especially emphasizes high reliability and low DPPM. Does our enterprise have the accumulation of technology and experience in high reliability manufacturing? Is it consistent with the future product development direction? Is the process control in accordance with the requirements of TS16949? Has a low DPPM been achieved? All of these should be carefully evaluated. It will hurt the enterprise itself to enter blindly just to see this attractive cake.
The following provides some special practices of some representative PCB manufacturers specializing in the production of automotive PCB in the testing process for reference to PCB colleagues:
1. Secondary test method
Some PCB manufacturers adopt the "secondary test method" to improve the rate of finding defective boards after the first high-voltage electrical breakdown.
2. Bad board anti fool test system
More and more PCB manufacturers have installed "good board marking system" and "bad board error proofing box" in the optical board testing machine to effectively avoid man-made 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. Bad board error proofing box means that during the test, when the PASS board is tested, the test system outputs the box opening signal; On the contrary, when a bad board is tested, the box is closed to allow the operator to correctly place the tested circuit board.
3. Establish PPm quality system
At present, the PPm (parts per million) quality system has been widely used in PCB manufacturers. Among many of our customers, Hitachi ChemICAl in Singapore is the most worthy to learn from its application and achievements. There are more than 20 people in the factory who are specially responsible for the statistical analysis of the quality abnormalities of online PCB and PCB quality abnormal returns. The SPC production process statistical analysis method is used to classify and statistically analyze each piece of bad board and each piece of returned defective board, and analyze which manufacturing process produces bad and defective boards in combination with auxiliary tools such as microsection. According to the statistical data results, solve the problems in the process purposefully.
4. Comparative test
Some customers use two different brands of PCBs in different batches for comparative testing, and track the PPm situation of the corresponding batches, so as to understand the performance of the two testing machines, so as to select a better performance testing machine for testing automotive PCBs
5. Improve test parameters
Select higher test parameters to strictly detect such PCBs PCBA OEM OEM substitute materials because if higher voltage and threshold value are selected and the number of high-voltage reading leakage is increased, the detection rate of PCB defective boards can be improved. For example, a large Taiwan funded PCB enterprise in Suzhou used 300V, 30M, and 20W PCBs for testing automobile PCBs
This article is about the method of optimizing the defect rate of automotive PCB in the testing process of automotive PCB enterprises