JOINT RELIABILITY OF SOLDER JOINT BETWEEN Sn-yAg SOLDER AND Ni-P UNDER BUMP METALLIC LAYER BY COBALT ADDITION

Abstract

An improvement of joint reliability between Sn-yAg (0≦y≦4.0) solder and Ni—P under-bump metallic layers is achieved by cobalt (Co) addition. A solder joint with improved joint reliability is formed between a solder part of an electronic packaging and an under-bump metallic (UBM) layer, which has a specific structure comprising Sn-yAg-xCo (0.02≦x≦0.1, 0≦y≦4.0) alloy solder containing cobalt (Co) ingredient bonded to a Ni—P UBM. Also, a solder joint with a joint structure comprising Sn-yAg-xCo (0.02≦x≦0.1, 0≦y≦4.0) alloy solder with addition of Co ingredient and Ni—P UBM is formed, which is inserted between a PCB substrate and a silicon chip to join the same.

Dependencies are inferred from the claim text.