An Investigation of Lead Free and Bromine Free Technologies for Medium Power Semiconductor Packaging

Abstract

Over recent years there has been a growing interest in the removal or substitution of Lead, Bromine and other hazardous chemicals from electronic and electrical equipment. This relates primarily to products whose end of life disposal relies on the use of landfill sites or increasingly on recycling. The driving force for these changes come from both legislation such as that proposed by the European Union [1] and also from consumer awareness. The implications of the move towards more environmentally friendly electronics extend right down the level of discrete component packages including those produced in large numbers by the power semiconductor industry. In the present paper the technical challenges associated with the development of a lead and bromine free medium power packaging are discussed and the results of ongoing investigations are presented. The major challenges in this area relate not only to the substitution of key elements but also to ensuring compatibility with the higher reflow temperatures which may be associated with Pb-free surface mount processing. This raises particular issues with respect to the die attach material, which is often a high Pb soft solder; the encapsulation compounds which tend to rely on Bromine and Antimony compounds for their flame retardant properties; and the device plating which must be compatible with Pb-free board attach solders.