A study of large area bonding technologies and their application in electronic industry

As high-power electronic devices are in a rapid developing speed, the topic of large area bonding in electronics emerged in recent years. The needs such as die-attach for large area chip (>10mm x 10 mm), high thermal dissipation power baseplate/heatsink attachment (connect devices to heatsink/baseplate) lead to the demand for reliable large area bonding technology with excellent thermal performance. However, the current adapted solutions are with various advantages and disadvantages. Epoxy-based adhesive is a versatile technology with excellent processibility, whereas the low thermal conductivity and reliability due to the high organic content in various cases cannot meet application requirements. The other commonly adopted technology is Sn-based solder paste technology, which is matured and cost effective with higher thermal performance. On the other hand, the low melting point and relatively high process temperature limits the packaging design and system reliability performance. Additionally, although the thermal conductivity is much better than epoxy-based adhesive, for high power application, it is not sufficient. Furthermore, in the past years, silver sintering has become an emerging solution for large area bonding, especially for high power and automotive applications due to the high thermal conductivity and reliability it can offer. Nonetheless, cost and many technical difficulties are existing that limits the adoption of this novel technology, such as relatively high process temperature, high mechanical pressure needed, voiding channels, and pick and place of the parts. Therefore, it seems of vital importance to have a comprehensive analysis of the current solutions to make proper suggestions of suitable applications. Moreover, for novel technology, such as silver sinter, the technology gaps and scientific challenges should be identified for accelerating the adoption.In this study, currently adopted large area bonging technologies and their merits and demerits are reviewed and discussed. The most suitable applications for each technology are suggested. In addition, the current technology gaps of silver sintering for large area bonding are shown, and the scientific challenges to fill in these gaps are presented as well.