High-Reliability Thermocompression Bonding for Hybrid Applications

The problem of producing reliable thennocomprassion gold ball bonds to aluminum metallization has been discussed by many authors. In most of these discussions, little information is provided to relate bond reliability to process parameters-cleanliness and bonder settings. The influence of bond and capillary temperatures upon bond integrity is discussed. The use of beryllia capillaries to achieve the high capillary temperatures achievable with pulse tip bonding without sacrificing production throughput is discussed. An accelerated life test for ascertaining bond reliability is discussed and shown to be an effective tool for process prove-in. Finally, a bonding technique is discussed that not only meets the requirements of MIL STD 883A, but also will withstand temperature stresses equivalent to 300°C storage for 4 h, 2000 h of accelerated operating life, and 1300 temperature cycles.