【摘要】 用直径为200~500μm的Sn-3.0Ag-0.5Cu无铅焊球分别在Ni和Cu焊盘上制作焊点,并对焊后和时效200h后的焊点进行剪切测试,并采用SEM观察剪切断口形貌。结果表明,焊后和时效200 h后焊点接头的剪切强度都随焊球尺寸增大而减小。焊后断口处韧窝形状为抛物线型,断裂方式为韧性断裂;随着焊球尺寸的增大,剪切断口处的韧窝数量增多,韧窝的变小变浅。时效200 h后,韧窝变浅,趋于平坦,韧窝数量也明显减少,材料的韧性下降,脆性增加,断裂方式由韧性向脆性发生转变。更多还原

【Abstract】 Solder spots were produced by Sn-3.0Ag-0.5Cu lead-free solder balls of diameters of 200-500 μm on plates of Ni and Cu,respectively,and shear tests of solder spots were carried out after soldering and aging 200 h,respectively,to observe the shear fractures by SEM.The results show that the shear strengths decrease with ball diameter increasing both after soldering and aging 200 h.The fracture toughness nests are parabolic shape after soldering,fracture mode is ductile fracture;with solder spots size increasing,the number of fracture toughness nests increases and toughness nests become shallow and small.After aging 200 h,toughness nests become shallow and tend flattening.The number of toughness nests significantly reduces.The plasticity of the material decreases and brittleness increases.The fracture mode transforms from the ductile fracture to brittle fracture.更多还原