Use of a Ni Interlayer to Improve the Thermal Cycling Reliability of Cu/Sapphire Bilayers

The thermal cycling reliability of ceramic/metal laminates is critical for their applications in microelectronic modules. A eutectic bonding process is used to prepare copper/sapphire bilayers in this study. Due to elastic and thermal mismatches between alumina and copper, the Cu/sapphire bilayer cannot pass a thermal cycling test. The thermal cycling reliability can be improved through the use of a metallic nickel interlayer. During the bonding process, the nickel interlayer was oxidized first, reacted with alumina to form a NiAl 2 O 4 spinel phase. The thermal diffusivity of the bilayer with spinel interphase remains high after the temperature cycling test.