Interactive fault isolation of analog hybrid circuit cards

Modern custom hybrids which contain many analog and also digital circuits in a single flatpack, have increased the functional density of circuit cards 4 to 6 times. The consolidation of many complex functions and differing technologies on a single card has exposed the need for new fault isolation techniques, particularly for the manufacturing environment, due to high first-time through failure rates, the difficulty and cost of manual fault isolation, and the large cost of hybrid replacement. The interactive fault isolation technique optimizes the key attributes of the ATE and the human: the ATE rapidly and accurately characterizes the analog fault signatures, but the actual diagnosis is performed off-line with the aid of a fault dictionary by a human. Fault signatures of unknown signals are rapidly acquired at connector pins and at component nodes with an adaptively programmed DMM, counter, and Waveform analyzer which are appro priately connected over the ATE's instrument bus. The acquired signal characteristics are tested for validity prior to display and printing. The interactive technique does not require the development of individual diagnostic programs for each circuit card and is applicable to existing 2nd and 3rd generation ATE.