Thermosonic wire-bonding at bonding temperatures below 100°C

Thermosonic (TS) ball-wedge bonding with gold bonding wires is still the dominating technology for the assembly of semiconductor devices. A result of the broader use of temperature sensible and low cost materials is the demand to decrease the bond temperature. The aim of the research was to reduce the bond temperature for Au-TS-ball-wedge bonding under industrial conditions below 100°C with a 120 kHz bonder through a specific impact of the wire material and bonding parameters. Standard gold bonding wire, alloyed, endowed and coated gold bonding wires were chosen to investigate the impact of different wire materials. Ni/Pd/Au coated FR5 circuit boards were used as substrates and statistical methods (DoE) were applied to find an optimised parameter combination for each wire. The criteria for a correct bond are regulated by the DVS-instruction 2811. Our results show that thermosonic wire-bonding is possible at room temperature, even with standard gold bonding wires.