Method of achieving solder ball coplanarity on ball grid array integrated circuit package
US6443351B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 26, 2000 |
| Grant date | Sep 3, 2002 |
| Priority date | — |
| Expiry date | May 26, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P70/50
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A BGA (Ball Grid Array) package fabrication method is proposed for the purpose of achieving solder ball coplanarity on a warped BGA package, such as a concavely-warped BGA package or a convexly-warped BGA package. The proposed method is characterized in the provision of a plurality of variably-sized solder-ball pads over the bottom surface of the substrate, each solder-ball pad having a specified size predetermined in accordance with pre-measured package warpage and predetermined relation of solder ball height against pad size. This provision allows the use of a solder mask having fixed-size openings, as contrary to the prior art that uses a solder mask having variably-sized openings, to allow the implanted solder balls to achieve coplanarity and have strengthened shear for robust solder joint.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.