两种加固方式下QFP封装芯片焊点受力工艺研究

摘要

航天QFP封装芯片的常用加固方式是"底部灌胶+四角固封"或"底部灌胶+四边固封",这两种加固方式的选择应根据产品结构及PCB的安装位置不同来确定,选择不当会导致芯片焊点在受热的情况下脱焊,造成性能异常.研究了某航天设备在高温试验中QFP封装芯片引脚处焊点失效产生的机理,通过试验件对随机振动和高温浸泡试验时焊点的受力情况进行仿真分析,获得焊点在各试验阶段的最大应力值,并判断该应力能否引起焊点脱焊失效,从而确定了该设备中QFP封装芯片的可靠加固方式.%Generally, QFP chips in aerospace products are reinforced with two methods, daubing sealant at bottom + encapsulating at four corners or daubing sealant at bottom + encapsulating on four sides. The selection of those two methods rests with product structure and fixing position of PCB, and improper selection will cause chips solder joint failure in heat environment, then cause product performance worsening. Researched mechanization on solder joint failure at QFP chip pins during the heat experiments of a certain aerospace product. Based on an experiment component, Simulated and analyzed mechanical properties of solder spots during random vibrating and heat soaking experiments. And obtained the maximum stress values of solder spots during different periods, analyzed that whether they would cause solder joint failure, then determined the reliable reinforced method of QFP chips in the product.