Loss of Solderability and Dewetting

Abstract

The loss of solderability and dewetting is a problem that is often observed in the manufacturing environment but not well understood. This lack of understanding as to the exact origins of this phenomenon and the conditions which lead to it make it difficult to ensure a reliable means of predicting the conditions for limiting dewetting. This chapter will aim to address the fundamental materials science issues that we feel may govern the dewetting or partial wetting phenomenon. The emphasis of this chapter is those aspects of the extensive literature on wetting phenomena in general that may have a direct bearing on the causes of dewetting of solders. Specifically, the issues of wetting instabilities and their relationship to the dynamics of wetting will be stressed. It is proposed as well to juxtapose the continuum descriptions of wetting phenomena with microstructural parameters that may affect the partial wetting or dewetting process. Particular attention will be paid to the possible role of intermetallic formation at the solder substrate interface on the stability of the wetting phenomena (Figure 5–1).