考虑扭率的焊点振动疲劳寿命及芯片位置优化

Chip Location Optimization Taking into Consideration of Torsional Curvature of PCB to Reduce the Fatigue of Solder Joint

摘要: 芯片焊点寿命的长短和芯片所处位置的曲率和扭率都有关系,但是扭率对寿命的影响总是被忽略。讨论了扭率和曲率的关系,认为扭率和曲率在一个数量级上,不能忽略。进而得出了在考虑扭率的焊点振动冲击疲劳寿命公式。并且对某航空用SMT电路板进行模态测试,发现芯片位置对焊点的影响很大,在此基础上进行了芯片的位置优化,提出优化措施以提高焊点的可靠性。

Abstract: Whether fatigue of solder joint and the location of the chip are related to the curvature and torsional curvature of PCB are discussed. The torsional curvature is always neglected. In this paper the relationship of curvature and torsional curvature is discussed and a formula for fatigue of solder joint considering torsional curvature is obtained. Meanwhile, the location optimization considering curvature and torsional curvature is performed and four location areas are obtained to locate the chip for increasing the fatigue life of solder joints.