Testing fixture and method for circuit traces on a flexible substrate

Abstract

A mechanism is provided for testing circuit traces extending along a flexible substrate, which is fed in a longitudinal direction between an upper plate and a lower plate. The upper plate includes a number of upper apertures extending across the flexible substrate and a number of upper segments, also extending across the flexible substrate, between adjacent apertures. The lower plate includes lower segments extending under the upper apertures and lower apertures extending under the upper segments. Two upper test probes are moved above the flexible substrate, while two lower test probes are moved under the flexible substrate. Tests are applied to both sides of the flexible substrate as the probes are brought into contact with test points in the areas accessible through the upper and lower apertures, with segments extending along the apertures on the opposite sides of the flexible substrate providing a backing surface for probe contact. A two-probe method may be used to determine the electrical characteristics of a circuit trace extending between test points, or a single-probe method may be used to determine the capacitance between a circuit trace and the plates. Circuit areas on the substrate are moved between the plates in a series of incremental motions to expose various points through the apertures as required to complete the testing process.