A Metallurgical Basis for the Non-Destructive Wire-Bond Pull-Test

Non-destructive wire-bond pull tests are often specified by high-reliability electronic device users in order to eliminate weak, poorly made wire bonds. The main problem with the test has been in establishing a pull-force level which will assure that the bonds are adequately strong but will not damage them during the test. In the present work, factors affecting the non-destructive wire-bond pull-test are examined. The variables, such as wire and bond-loop elongation, bond geometry, bond deformation, and the mean and standard deviation of the destructive bond pull test are studied to determine theit influence on the non-destructive test. Different pull-force criteria are derived for wire with high elongation, such as is used in power devices, and for wire with low elongation, typically used for bonding integrated circuits.