TWI Industrial Member Report Summary 295/1986
N R Stockham
The feasibility of forming 200µm diameter Al wire interconnections by ultrasonic ball/wedge bonding has been investigated. A commercial ultrasonic wedge/wedge bonding machine has been converted to operate in a ball/wedge mode. This report describes the modifications made to this machine and details the results of ball/wedge bonding trials conducted between 200µm diameter Al-1%Si and Al wire and Al thin film coated Si, and unplated and Ni plated Cu substrate materials. Ball bonding trials have been conducted using a specially designed capillary to establish the optimum conditions when bonding these wires to the Al thin film coated Si. These trials have shown that A1-1%Si and Al wires produce bonds with similar shear strengths (16.2N and 14.4N) but that the Al wire results in greater bond spreads and relatively weaker 90° pull strengths (Al-1%Si:2.8N, 70% wire strength, Al: 1.4N, 60% wire strength). Capillary wedge bonds in Al-1%Si and Al wires have been made to unplated and Ni plated Cu lead frames giving 30° pull strengths of 3.1-3.2N (~80% wire strength) and 1.9-2.1N (~90% wire strength) respectively when using both transverse and parallel vibrations.