表面実装微細はんだ接続部の疲労き裂発生および進展寿命の評価

概要

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Fatigue tests on solder joints of surface-mounted type electronic package models were carried out at different temperatures, cycling frequencies and controlled displacement amplitudes in order to examine the crack initiation life Nc, crack extension path, crack extension rate da/dN and crack extension life. The crack initiation life (Nc)_<cal> of solder joints was estimated using maximum equivalent inelastic strain calculated by three-dimensional elasto-inelastic finite element method (3D-FEM). The ratios Nc/(Nc)_<cal> were found 2.4〜9.8. Further, 2D-FEM crack extension analyses were performed to examine crack extension behaviors. The FEM analyses showed that crack extension path and rate were controlled by maximum opening stress range at crack tip, Δσ_<θmax>, in plastic zone under rather complicated stress tensor fields. Experimentally obtained crack extension rate was found to be related to Δσ_<θmax> in FEM analysis as da/dN=β [Δσ<θmax>]^α, with α=2.0 and β=2.65×10^<-10>mm^5/N^2 being determined independently of the test conditions. The calculated values of crack extension life by the FEM analysis using the above equation were in good agreement with the experimental ones.
社団法人日本機械学会の論文
1998-04-26