热插拔损伤电路的失效分析及整改

Failure Analysis and Rectification of Hot Swapping Damaged Circuit

对3100块板卡进行测试,其中2653块出现问题,不良率达到了86.6%,故障板卡上机后不能正常运行,且出现了供电电源短路的现象。对故障板卡进行技术分析之后发现,MCU有管脚被异常电压、电流击穿,导致管脚对地端、对电源端短路。客户在使用设计时对出现该问题的管脚未做任何相应的热插拔防护。根据客户板卡的实际应用情况,对该款板卡出现问题的管脚线路增加瞬态二极管(Transient Voltage Suppressor,TVS),减小浪涌冲击,使量产良率达到合格标准。

Tested on 3100 boards,2653 of them had problems,the defect rate reached 86.6%,the fault board could not operate normally after the machine was installed,and the phenomenon of short circuit of power supply appeared.After technical analysis of the faulty board,it was found that the MCU pin was broken down by abnormal voltage and current,resulting in short circuit of the pin to the ground and the power supply end.The customer did not make any corresponding hot-plug protection design for the pins with this problem during the application design.According to the actual application of the customer's board card,the TVS(transient voltage suppressor)is added to the pin line with problems of the board card to reduce the surge impact and make the yield of mass production reach the qualified standard.