Gold Ball Wire Bonding with Heated Tool for Automotive Microelectronics

Abstract

Microelectronics used in automotive applications have grown considerably in the last few years with more high tech electronics controlling more functions in automobiles. In an effort to have more precise control and to reduce vehicle weight manufacturers are integrating more functions into smaller packages. Many of these packages are embedded in molded plastic. This causes challenges when it comes to wirebonding these devices. They often cannot be heated to traditional Gold Ball Thermosonic wirebonding temperatures of 120 – 150C. However, using a heated capillary to bond the parts which remain at room temperature simplifies the process considerably. Alternatives such as pre-heating the parts in an oven and complex hot gas handler systems are not required. With a resistive wire coil heater surrounding a standard (or long capillary for deep access) sufficient heat can be provided to the wire bond site for a strong and reliable interconnect. The bonding surface can be any material used in gold ball bonding: aluminum bond pads on die, plated contacts, ceramic substrates or plated copper traces on PCBs. This paper will show that this heated tool process has been successfully utilized with 1mil Au wire and many of the standard die and substrate materials with little impact on process parameters.