Mechanical characterization of nickel plated copper heat spreaders with different catalytic activation surface treatment techniques

Abstract

This paper studied the effects of different catalytic activation processes towards intermetallic diffusion and mechanical properties on nickel plated heat spreader after high temperature storage (HTS). Heat spreader performs as medium to dissipate heat from silicon die towards heat-sink and is normally made by copper that is plated with nickel to improve wear resistance and prevent oxidation of copper. Two types of heat spreader that using galvanic initiation and thin nickel-copper electrodeposition surface treatment technique had been studied on their hardness and moduli by using Micro Tester and Nano-indenter. Besides, HTS tests were performed to investigate intermetallic diffusion between the nickel and copper layers. Young’s moduli of the heat spreaders which were plated by galvanic initiation and thin nickel-copper strike electroless nickel plating catalytic activation techniques were 45 to 65 GPa and 60 to 80 GPa, respectively. The results found that thin nickel-copper electrodeposition technique gave a higher modulus for the heat spreader and this also increased the mechanical strength of heat spreader. Diffusion also took place with a very slow rate in nickel-copper layer. Key words: Heat spreader, electroless nickel plating, galvanic initiation, thin nickel-copper electrodeposition, high temperature storage.