Sand76-5286 Gold Alumium Interconnect Stability on Thin Film Hybrid Microcircuit Substrates

The effects of gold aluminum intermetallic growth on the stability of interconnects to thin film hybrid microcircuits were studied. Three different metallization systems were evaluated using three types of bonding wire. Tantalum-nitride-chromium-gold was bonded using 0.031 mm alurminum 1% Si wire and 0.031 mm aluminum 1% Mg wire. These two wire types were also bonded to substrates metallized with tantalum-nitride titanium-palladium-gold. Also, gold wire (0.025 mm) was bonded to aluminum metallization. These metallization-bond systems were evaluated by subjecting the tests specimens to various known temperatures and time environments followed by loop pull tests to destruction, bond shear tests to destruction, and four-point probe electrical resistance measurements. The environments included: 1. 1000 hrs. of storage at 100°C, 200°C, and 300°C. 2. Temperature cycling from -40°C to 200°C for 10, 50, 100, 500, 1000 cycles. The data shows that the electrical resistance shows drastic increases long before mechanical integrity is degraded. It was not uncommon to see kilohms. The results of aging of gold wire bonding to aluminum metallized substrates is described. Stabilized and unstabilized wire were used, and the effects of time and temperature on bond integrity are reported. Both were types degraded mechanically and electrically with little differences between the two.