Solder bump fabricated method incorporate with electroless deposit and dip solder
US5795619A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 13, 1995 |
| Grant date | Aug 18, 1998 |
| Priority date | — |
| Expiry date | Dec 13, 2015 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C18/31
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
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, Z.sub.n o, 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 NaH.sub.2 PO.sub.2. 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.degree..about.80.degree. C. higher than the melting point of the corresponding Pb--Sn alloy.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.