METHOD OF MAKING HIGH DENSITY SOLDER BUMPS AND A SUBSTRATE SOCKET FOR HIGH DENSITY SOLDER BUMPS

摘要

A method of forming solder bumps includes the steps of applying a thick layer of solder resist (22) to a substrate (20). The resist is selectively removed to provide wells (23) at solder pads (21) on the substrate. The solder paste (24) is applied to the substrate in the wells. The solder paste is reflowed to form solder bumps (25) on the pads. A socket for a solder bumped member (36) is obtained by first providing a substrate (30) having metallized pads corresponding to the solder bumps of the member. A thick layer of photo definable solder resist (32) is applied to the substrate. The resist is selectively removed to provide wells (33) at the metallized pads (31) of the substrate. Solder paste (34) is then deposited in the wells. The solder bumped member (36) can then be positioned so that the solder bumps (37) are located in the wells. The solder paste (34) is reflowed to bond to the solder bumps (37) and the metallized pads (31). The solder paste (34) can be selected to have a lower melting temperature than the solder bumps (37). By reflowing the solder paste (34) at a temperature lower than the melting temperature of the solder bumps (37), the paste can wet to and blend with the solder bumps while not causing the solder bumps to reflow.