Method for monitoring the length of constant-wire-length bonds and apparatus therefor
US6661525B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 11, 2001 |
| Grant date | Dec 9, 2003 |
| Priority date | — |
| Expiry date | Feb 8, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/30107
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
On a circuit-board intended for constant-wire-length (CWL) bonding, one or more special “test” pairs of bonding pads are provided along with, in each case, a series of markings adjacent the pads. In use, the board is populated with CWL bonds (this includes the normal circuit-related RF bond-pads as well as the test bond-pads) and the test bonds are distorted so that the bond-wires in question lie aligned against the markings. The alignment position relative to the markings indicates whether the bond-wires for the whole board are of correct or incorrect length. Measurement may be either absolute, in which case the markings are associated with a scale indication, or relative, in which case one of the markings will usually be visibly distinguished from the rest in some way. Depending on the length determination, the bond-forming device (e.g., ball and wedge) is adjusted so as to reduce any difference between the indicated length and the desired length when the next board is populated or when the next multi-board production run takes place.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.