Stack Bonding Technique Using Heavy Aluminum Ribbon Wires

The use of Aluminum ribbon wire is aimed to reduce the resistance of the interconnect material and improve product R_DS(ON). Competition in the market in terms of low R_DS(ON) performance package challenges semiconductor companies to venture into new technology, innovation, process, wafer fabrication, package design changes. Ribbon bonding introduction using wide ribbon wire is one of the process innovation to enhance device performance to attain a low R_DS(ON) product. To further augment the electrical performance, bonding configurations are investigated including double stitched bonding and stack bonding technique on the source lead to accommodate additional ribbon wire without modifying the existing leadframe. Finite Element Analysis is initially utilized to compare the R_DS(ON) improvement of various interconnect options and then verified in actual measurements. This paper suggests a method of improving the on state resistance of a power package by stacking two layers of wide Aluminum ribbon wires at the source leadpost. This maximizes the number of wide ribbon wires on a source lead while maintaining its manufacturability. The DPAK/IPAK package is used as a test vehicle for this study but the technology is intended to be propagated to similar packages.