Materials interaction, shearing strength, and bump growth of Al/Cu/electroless nickel/Sn-Pb solder bumps were investigated with respect to reflow conditions. Shearing strength of the solder bump is as high as 64 g/bump for a bump pad dimension of 100×100 m. Reflow temperature enhances the shearing strength while repeating reflow downgrades the shearing strength to a lowest value of 35 g/bump. A greater bump height is achieved when reflow was conducted at a slower heating rate. Cu penetrates the electroless nickel (EN) layer after reflow, while Al remains unmoved. The diffusion behavior of Cu through the EN layer is discussed. Ni-Sn and Cu-Sn intermetallic compounds form during reflow.
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering