Subject: Platinum wire bonding
Are there any suggestions for settings/substrate temperature to successfully bond (1 & 2 mil) Pt wire to Pt pads?
Ultrasonic bonding of platinum (Pt) wire requires a different approach to conventional aluminium and gold bonding processes.
Pt is a harder material than both Al and Au, and work hardens significantly during ultrasonic bonding. Increasing the power setting on the wire bonder increases the amplitude of the ultrasonic vibration, which would increase the propensity of Pt to work harden.
Recommendations for bonding Pt wire are to use high substrate heating, e.g 300ºC with minimum ultrasonic power. Adjust the time and force settings as required to produce a bond.
Parallel gap resistance welding should be considered as an alternative and often preferred method of bonding Pt wire.
Answer posted 14 November 2005
Submitted by: Mr Paul Richard
Affiliation: Georgetown University, Department of Physics
Answered by: Chris Otter
Affiliation: TWI, Cambridge, U.K.