Effect of coupling agent on adhesion of underfill on copper

The effects of coupling treatment on mechanical properties of UF and adhesion on the Cu plate have been examined using standard UF materials which are composed bisphenol F-type epoxy resin and spheroidal SiO₂ filler. As the result, elastic modulus and tensile strength of UF was improved by coupling treatment. Fracture strain was improved at R.T., but was decreased at 80°C and 120°C by coupling treatment. Tensile strength depends on the interfacial state of the matrix resin and fillers. Peeling of fillers from the matrix resin was suppressed by coupling treatment at the temperature under 80°C. Fracture mode of UF with coupling treatment changed from the matrix fracture to the interfacial fracture in the boundary of Tg. Moreover, coupling treatment affects on the relaxation behavior of elastic modulus of UF and makes the relaxation time of storage modulus shift to the longer side. Shear strength of the UF bump bonded on the Cu plate was increased by coupling treatment.