Biography: Nickolas Kam completed his undergrad at the University of Waterloo in mechanical engineering. He is now pursuing his master's as a member of the CAMJ lab group, working primarily in electronic packaging and wirebonding technology.
Abstract: Wirebonding performed at elevated temperatures is the standard interconnect process for integrated circuits, typically with the use of low‐cost copper bonding wire. However, for specific applications it is necessary for wire bonds to be reliably joined at room‐temperature (23°C). This paper details the development of a room‐ temperature ball bonding process using a 2‐stage optimization method. The first stage optimizes ball geometry by applying a 32 design of experiment to bonding parameters impact force (IF) and EFO current. In the second stage bond shear strength is optimized by stepwise increase in ultrasonic amplitude. Target ball bond values were attained at optimized parameters: IF of 1331 mN, EFO current of 59.9 mA, and an ultrasonic amplitude of 26.46 %. Failure by pad lifting was observed at excessive ultrasonic amplitudes above 40%, as determined by optical images at the shear interface. Bonding parameters at room‐temperature were increased compared to high temperature bonds (175°C) to account for the reduced thermal energy. For the same geometry at room‐temperature a 7% increase to impact force was required. EFO current levels remained relatively constant between the two bonding temperatures. For the same shear strength at room‐temperature a 14% increase in ultrasound amplitude was required.
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