BGA-ICパッケージはんだ接合部の振動疲労特性 : 第1報,横振動における,鉛フリーはんだと鉛はんだの比較

概要

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In this paper, a new method was proposed for evaluating the high-cycle fatigue strength of EGA (Ball Grid Array) packages with Pb-free solder and Pb solder due to a vibration. Attaching a weight induced mixed mode stress in the solder ball of a package. To consider the effect of a mixed mode stress occurred in a solder ball and a frequency to fatigue strength of solder ball, a test was carried out with the four kinds of weights which induced the different ratio of nominal normal stress and nominal shear stress in a solder ball (σ_n/τ_n=2,4,5, and 6) at various frequencies (10〜27Hz). Based on the nominal shear stress in solder balls, a new evaluation equation to consider the effect of a mixed mode stress in a solder ball was proposed and the scatters of the fatigue strength in Pb-free packages and Pb packages were evaluated with a Weibull distribution. From a successive observation of a cross section during a fatigue test, a position of crack initiation and a propagation path were found out. Although an intermetallic compounds in both of packages were confirmed by an EDX microprobe analysis, they don't contribute to the initiation of a crack in a solder ball.
一般社団法人日本機械学会の論文
2004-12-25