Direct EP/EPAG - Ultrathin Surface Finish for Soldering and Wire Bonding

Abstract

New challenges in the industry, new technical requirements, as well as cost and environmental regulations, require a constant search for alternative manufacturing solutions for the electronic packaging industry. Finer lines and spaces, higher frequencies, improved solder joint reliability and new challenges in wire bonding – both with existing wire technology such as Al and Au or novel types such as Cu or Cu-Pd – are just a few examples of technological advancements for surface finishes in the packaging industry. Additionally, the reduction and elimination of toxic and hazardous materials, as well as the drive to further reduce the manufacturing costs, are important requirements which has to be addressed. The new direct pure EP/EPAG surface finish is suggested as a solution to these challenges for the future. The direct EP/EPAG process allows the direct deposition of palladium on copper, without using any nickel. It is suitable for high frequency, for flexible applications, for gold, aluminum, gold, silver and copper wire bonding applications. The process proves superior solder joint strength for lead free and eutectic soldering and is compatible with many new base materials and soldermask types owing to its short deposit time and low temperature needs. Finally, the EP/EPAG process operates at a thickness of less than 300 nm, ideal for very fine lines and spaces. The EP/EPAG finish also features several environmental benefits, such as less water and energy consumption owing to reduced process steps and line lengths. The suggested paper will provide new wire bond data with silver, gold and copper wire bonding results. A technical comparison to a thin ENEPIG finish will be provided to show the differences in terms of soldering and solder joint reliability.