Method and circuit testing apparatus for equalizing a contact force between probes and pads
US5644249A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 7, 1996 |
| Grant date | Jul 1, 1997 |
| Priority date | — |
| Expiry date | Jun 7, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R1/07314
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
This invention presents a method and a mechanism for contacting a set of vertical probes of a circuit testing mechanism with a set of pads or bumps of a circuit under test. The vertical probes have a circular cross section, a tip portion of length L1 and a beam portion of length L2, such that the beam portion extends at a right angle to the tip portion. The tip portion is guided through a guide hole to the pads of the circuit under test and the beam portion secured by its end. In this geometry the contact force between the probe and the pad is described by the relation: ##EQU1## where D.sub.v is a vertical deflection of the probe, I is an area moment of inertia of the probe about its axis, and E is a Young's modulus of the probe. The tip length L1 and beam length L2 are selected for each of the vertical probes in such a way the contact force F in this relation is kept constant thus ensuring that the contact force F between the vertical probes and pads remains substantially equal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.