Computational Study of Erosion Wear of Capillary Used in Laser Solder Ball Jetting Process

Abstract

Solder Ball Bumper Jetting Process is used for high precision soldering in small area with high productivity. Cemented carbide (WC-Co) is the common material used for capillary due to its high strength and good wear resistance. Small paritcle induced during soldering process could cause particle erosion wear and it is found to be one of the surface failure mostly controlling capillary in-service life. The particles were expected to be hard particle generated by surface wear in the earlier process. This research aims to study the material behavior under particle impact to increase the understanding of capillary failure based on particle impingement erosion wear using Finite Element Method (FEM). The effect of contact paramters, i.e. impact angle of particle and particle size, on failure of capillary tip was studied. The impact angle variation between 10, 30, 60, 90 degree and particle size variation of 0.5, 0.75, 1 micrometer were considered. The result showed that higher angle of impact can lead to higher stress developed while particle size effect depends strongly on the contact area which relies on impact angle. In case of 60 and 90 degree of impact, results showed a trend of decreasing developted stress with increasing particle size. While 10 and 30 degree of impact showed a trend of increasing in developed stress when particle size increased. The research results could be used as guidelines to improve the capillary design or soldering process to incrase the capillary in-service life or minimize the chance for capillary failure at unexpected short time period.