Design and characterization of thermal conductive wafer coating in thin small outline package for automotive product application

Abstract

The thermal conductive die attach (DA) material is very important component and it is function to create a joint between die and leadrame as well as to dissipate heat from die throughout the package. However, the dispensing DA material is giving problems, which is epoxy overflow, die tilted especially when dealing with small die size (ranging 15 to 30 mils). Because of this problem, industries are using noncon-ductive dispensing epoxy without metal content and resulting good for manufacturing. There is another problem when using nonconductive epoxy which reducing in thermal and performance of the device. In this paper, we presents conductive material coated at backside of wafer (conductive WBC) and giving excellent thermal and device performance and good for integrated device assembly manufacturing. In the most stringent automotive application, device performance is critical to component level. The small and thin die assembled in Thin Small Outline Package (TSOP), good thermal conductive die attach material is required, together with excellent robustness in oxidation control, manufacturability and reliability. Upon completion of multiple material screening, wafer back coating (WBC) material had selected. It is thermal conductivity can reach approximately 2.2-W/mK and which is enough for lower power devices as well as good in thermal conductivity. With all the improved assembly processes, conductive wafer coated material achieved good manufacturability, excellent thermal performance, meeting customer specification and ready for high volume manufacturing.