摘要
在印制电路板的贴装过程中，焊点强度以及后期使用的可靠性越来越受到重视，本文探究了沉金板焊接过程中IMC生长机理以及针状IMC导致焊点强度不足，导致早期失效的原因，通过设计不同的热处理条件以及焊料制备样品，通过推拉力手段测试焊点强度，辅以SEM电镜观察焊点断裂面，确认断裂面形貌以及元素组成，进而分析出IMC生长与温度的关系，发现针状IMC产生与Ag元素有关，而且焊点断裂的本质原因是富磷层厚度。通过本文的研究，可以为沉金板焊接参数优化，防止焊点旱期失效，为提高焊点可靠性提供依据。
In the process of PCB SMT, the solder joint strength and reliability get more and more attentions. The article,explored the IMC growth mechanism of ENIG and the reason analysis of needle IMC in the SMT process, which was result in insufficient of the early solder joint strength. We designed for the examples, using the different heat treatment conditions and welding flux. We tested the strength of the solder joint by the push pull shear apparatus, and then observed the fracture in order to know the fracture morphology and the composition of elements, then we can know the relationship between IMC growth and the temperature, and we fred the relationship between the needle IMC and Ag. Besides the essence reason of the solder joint fracture is the thickness of the rich phosphor layer. Through this study, optimize the welding process parameters of ENIG, prevent premature failure of the solder joints and provide evidences to enhance the solder joint reliability.
出处
《印制电路信息》
2015年第A01期165-172,共8页
Printed Circuit Information
关键词
焊点可靠性
推拉力测试
形貌
焊点失效
沉金
Reliability of Solder Joints
Push Pull Shear Test
Fracture Morphology
Failure of Solder Points
ENIG
