Shear Fracture Behavior on Ball Grid Arrayed Tin–Silver–Copper Solder/Pure Copper Pad Joint Interface

Abstract

Shear strength of Sn-0.39 mass%-3.9 mass%Ag-0.5 mass%Cu lead free solder joint interface on non-resist pure Cu pad were measured to evaluate the true joint strength. Shear test was carried out under the shear speed, V s ¼ 0:14 mm/s and the shear height, Z ¼ 0 mm from the nonresist substrate surface. Shear fracture generated and propagated complicatedly on the joint interface. The shear strength using the non-resist pure Cu pad was lower than that using the FR-4 print board. The reaction layer was composed of Cu 5:6 Sn and Cu 6 Sn 5 intermetallic compound with column shape on the joint interface. Reaction layer thickness, t, column space, s and column width, w have been investigated to analyze the layer structure morphology. Silver composition in the solder influenced on shear strength but not on reaction layer structure morphology. Shear crack propagated intricately in the solder side and the reaction layer side. Shear fracture had the ductile deformation area of the solder and the brittle fracture area of the intermetallic compound.

Morphology and Pull Strength of Sn-Ag(-Co) Solder Joint with Copper Pad

“…The joint strength has been investigated by conducting shear tests and pull tests. [18][19][20][21] In this study, the reaction between Sn-Ag(-Co) solder and a Cu pad was investigated in order to clarify the effect of the addition of Co to Sn-Ag solder on the formation of IMC at the interface and the joint strength of the solder with a Cu pad.…”