SnAgCu表面贴装焊点在时效和热循环过程中的组织及剪切强度变化

EFFECTS OF AGING AND THERMAL CYCLING ON THE MICROSTRUCTURE AND SHEAR STRENGTH OF SnAgCu SURFACE MOUNT SOLDER JOINT

研究了 ＳｎＡｇＣｕ／Ｃｕ和 ＳｎＡｇＣｕ／Ｎｉ－Ｐ／Ｃｕ表面贴装焊点在时效和热循环过程中的微结构及剪切强度的变化结果表明， ＳｎＡｇＣｕ与 Ｃｕ的反应速率大于其与 Ｎｉ－Ｐ的反应速率．经长时间时效后， ＳｎＡｇＣｕ／Ｃｕ焊点中 ＳｎＡｇＣｕ与 Ｃｕ的界面成为弱区，而 ＳｎＡｇＣｕ／Ｎｉ－Ｐ／Ｃｕ焊点的剪切断裂则发生在 Ｎｉ－Ｐ与 Ｃｕ的界面．热循环过程中两种焊点均产生裂纹且强度下降．长时间热循环后 Ｎｉ－Ｐ与 Ｃｕ分层脱开， ＳｎＡｇＣｕ／Ｎｉ－Ｐ焊点失去强度．

The microstructure and shear strength changes of SnAgCu/Cu and SnAgCu/Ni-P/Cu surface mount solder joints during aging at 150 degreesC and thermal cycling between -40 degreesC and 150 degreesC were investigated. The reaction rate between SnAgCu and Cu is higher than that between SnAgCu and Ni-P. After long time aging, the SnAgCu/Cu interface becomes the weakest region, while the shear force induced crack in SnAgCu/Ni-P/Cu solder joint happens at the interface of Ni-P/Cu. During thermal cycling, cracks develop in both solder joints and the shear strength decreases. After long time cycling, the Ni-P layer separates from Cu substrate and the shear strength of SnAgCu/Ni-P solder joint decreases drastically.