FCBGA高铅凸块non-wet的失效机制及基于封装工艺的解决方案

FCBGA封装芯片中晶片凸块和基片凸块之间的non-wet问题是一个已知的能导致严重低良品率和引入可靠性隐患的问题。本文研究了FCBGA封装形式中non-wet的典型失效模式和揭示了其生成机制， 并确定了晶片凸块表面残留的铅和锡氧化物是导致晶片凸块和基片凸块之间non-wet的主要成因。晶片凸块回流工艺实验表明，优化后的回流时间和氢气流速能显著减少和去除晶片凸块表面的铅锡氧化物，从而能把non-wet引起的报废率降低90%左右。 失效分析结果和量产数据都验证了本文揭示的non-wet的失效机制是正确的。 研究确定的凸块回流工艺的优化参数显著降低了non-wet引起的报废率，从而大大地节省了制造成本和提高了产能利用率。

Failure mechanisms and assembly-process-based solution of FCBGA high lead C4 bump non-wetting

This paper studies the typical failure modes and failure mechanisms of non-wetting in an FCBGA (flip chip ball grid array) assembly. We have identified that the residual lead and tin oxide layer on the surface of the die bumps as the primary contributor to non-wetting between die bumps and substrate bumps during the chip-attach reflow process. Experiments with bump reflow parameters revealed that an optimized reflow dwell time and H₂ flow rate in the reflow oven can significantly reduce the amount of lead and tin oxides on the surface of the die bumps, thereby reducing the non-wetting failure rate by about 90%. Both failure analysis results and mass production data validate the non-wetting failure mechanisms identified by this study. As a result of the reflow process optimization, the failure rate associated with non-wetting is significantly reduced, which further saves manufacturing cost and increases capacity utilization.