BGA package substrate

摘要

It is an object of the present invention to provide a BGA package substrate capable of forming a thin and light BGA package which causes no crack in solder balls during temperature cycling tests and which permits fine-pitch packaging.According to the present invention, a conductive pattern 3 is formed on a solder resist layer 2 made of polyimide and a cover film 4 is formed on the conductive pattern 3. The conductive pattern 3 includes a land 3a for connection to a mother board and a bonding pad 3b for connection to an IC. The solder resist layer 2 has an opening 5 to leave an overlap on the periphery of the land 3a, and an end of the opening 5 is tapered. A solder ball 6 is formed on the land 3a.