Factors governing the loop profile in Au bonding wire

It is found by studying the factors governing the loop profile in Au bonding wires that the thermal history in forming the ball caused the observed V-shaped hardness distribution in the heat affected zone. It is proved by combining calculation and simulation that the minimum hardness portion is a dominant factor governing the loop height. As recent LSI packaging is becoming thinner and thinner, a low profile wire is required for the bonding wire, which can be developed by utilizing this approach. >