中間層を有する三次元接着接合体の角部における熱残留応力の特異場の強さ: 中間層のヤング率を変えた場合

摘要

小型化・高機能化が進む電子デバイスには多くの異材接合部がある．特に，それらのデバイスでは接合材料の物性値の違いから，接合過程において生じる界面端の熱残留応力により界面はく離が発生することがある．一般に，その熱残留応力は特異性を有している．したがって，界面の熱残留応力の測定・解析が盛んに行われている．接合体の特異応力場については古くから理論的にBogyやDempseyらにより調べられている．特異応力場は応力特異点を原点とする極座標系において，特異点からの距離の関数として表される．%A mismatch of material properties may cause stress singularity, which lead to the failure of bonding part in joints. It is very important to analyze a stress singularity field for evaluating the strength of interface in three-dimensional joints. Thermal residual stresses occur in a cooling process after bonding the joints at a high temperature, and the stress singularity for thermal stresses also occurs. In the present paper, a boundary element method and an eigen value analysis based on a finite element method are used for envaluating the intensity of singularity of residual thermal stresses at a vertex in joints. Three-dimensional boundary element program based on the fundamental solution for two-phase isotoropic body is used. The singular stress field for residual thermal stresses at the vertex in three-dimensional bonded structures with an interlayer is calculated with varying material properties of interlayer. Additionally, a relationship between Dundurs' parameter α_(3D) for three-dimensional stress states and the intensity of sigularity K_(θθ) Stress singularity field will be able to estimate for an arbitrary material combination in the present study using this relationship under thermal loadings.