Method for coplanarity inspection of package or substrate warpage for ball grid arrays, column arrays, and similar structures
US5465152A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 3, 1994 |
| Grant date | Nov 7, 1995 |
| Priority date | — |
| Expiry date | Jun 3, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/3511
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method for determining coplanarity with 3-D sensing means of substrates for ball grid array, column grid array, and similar surface mount integrated circuit chips, in which opaque fiducials are provided as index pads. Heights of the index pads are correlated with signal pad heights in a neighborhood about the index pads. The index pads are opaque to incident radiation from the 3-D sensor. The index pads reflect sufficient radiation to be detected easily by the 3-D sensor. The index pads are disposed in a prearranged pattern over a domain of ball grid array signal pads. The index pads are restricted to a predetermined range of heights.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.