Solder bump fabrication method
US5162257A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 13, 1991 |
| Grant date | Nov 10, 1992 |
| Priority date | — |
| Expiry date | Sep 13, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49117
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
The base of solder bumps is preserved by converting the under-bump metallurgy between the solder bump and contact pad into an intermetallic of the solder and the solderable component of the under-bump metallurgy prior to etching the under-bump metallurgy. The intermetallic is resistant to etchants which are used to etch the under-bump metallurgy between the contact pads. Accordingly, minimal undercutting of the solder bumps is produced, and the base size is preserved. The solder may be plated on the under-bump metallurgy over the contact pad through a patterned solder dam layer having a solder accumulation region thereon. The solder dam is preferably a thin film layer which may be accurately aligned to the underlying contact pad to confine the wetting of the molten solder during reflow. Misalignment between the solder bump and contact pad is thereby reduced. The solder bumps so formed include an intermetallic layer which extends beyond the bump to form a lip around the base of the bump. This lip provides extra protection for the solder bump.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.