向前兼容焊点的可靠性分析

在从有铅向无铅转换过程中,电子产品制造商不可避免会碰到同一组装过程中有铅和无铅同时存在的混合情况,这种情况下形成的混合焊点是很复杂的.因此,有必要对这种混合焊点进行可靠性分析.根据混合焊点的主要失效形式,对混合焊点的失效机理从组装工艺、热疲劳、时效、机械冲击和震动等四个方面进行分析;然后从设计、材料、工艺和环境等四个方面介绍了影响这类焊点可靠性的因素.分析结果显示,工艺对混合焊点的前期可靠性影响最大,环境对混合焊点的后期可靠性影响最大.工艺的影响主要体现在焊接工艺方面,环境的影响主要体现在温度负载方面.

Reliability analysis of forwards compatible solder joint

In the transition from lead to lead-free, for the manufacturers of electronic products, there is expected to be a period when lead and lead-flee materials will be used within the same mounting process, the mixed solder joint which formed in this situation is very complicated. Therefore, it is necessary to study the reliability of this mixed solder joint. According to the major failure modes of mixed solder joint, this paper analyses the mechanism of mixed solder joint from mounting process, thermal fatigue, ageing, mechanical collision and shock etc, then introduces the effect factors of reliability from design, material, process and environment etc. The analysis results show that process is the most important effect factor for the prophase reliability of mixed solder joint, and environment is the most important effect factor for the anaphase reliability of mixed solder joint. The effect of process mostly reflects on the soldering process, and the effect of environment mostly reflects on the temperature loading.