Using cone shaped search models to locate ball bonds on wire bonded devices
US5550763A · kind A · utility
Inventors
Key dates
| Filing date | May 2, 1994 |
| Grant date | Aug 27, 1996 |
| Priority date | — |
| Expiry date | May 2, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/14
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Method and apparatus for automatically locating the center of a ball bond of a wire to a lead frame and semiconductor chip or similar device; analyzing the optically sensed images; a bonding mechanism; and a host controller connected to the bonding mechanism, the movable platform. The present invention constructs a synthetic flattened cone model using a center radius, and monotonically increasing slope values to generate a model having a variation in grey levels, and inner and outer radii that will encompass expected size variations in a ball bond; sets a threshold for acceptable normalized correlation search results; acquires a digitized image of the bond, including a nominal location for the bond; conducts a normalized correlation search of the digitized image at the bond location, using the flattened synthetic cone model; and indicates the presence and location of the expected circular object as the location having the largest coefficient which exceeds a threshold.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.