Solder bump fabricated method incorporate with electroless deposit and dip solder

摘要

A process for preparing a solder bump can be prepared by the following procedure. The chip package was cleaned with an alkali or acid solution followed by Zn displacement (zincating)in a displacement solution which comprises NaOH, Zno, potassium sodium tartrate and sodium nitrate. After zinc displacement the chip package was performed the electroless Ni-Cu-P deposit in the strong reducing solution which contains NaH2PO2. The chip package deposited with Ni-Cu-P was then dipped into an organic solution as flux which is a mixture of the stearic acid and glutamic acid. Finally, dip soldering of the Ni-Cu-P deposited chip packages in a molten solder bath at a temperature 40 DEG DIFFERENCE 80 DEG C. higher than the melting point of the corresponding Pb-Sn alloy.