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Circuit Board Tester

IP.com Disclosure Number: IPCOM000040984D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hack, GE: AUTHOR

Abstract

In order to test a completed circuit board that interconnects a plurality of integrated components, the self test circuits built into the components can be used. An in-circuit tester can thereby address both manufacturing defects, such as board interconnects and assembly, as well as component defects.

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Circuit Board Tester

In order to test a completed circuit board that interconnects a plurality of integrated components, the self test circuits built into the components can be used. An in-circuit tester can thereby address both manufacturing defects, such as board interconnects and assembly, as well as component defects.

First, all signal nets are tested for shorts to each other or to ground or a power supply. Then all passive, non-logical components are measured for resistance, inductance or capacitance with power off. With power on, component level tests are applied to all driver-type components. Each integrated circuit component includes circuitry to allow the component to self-test itself when interfacing with a Test Module. Pseudo-random patterns are applied to the boundary scan latches and the output is compared to the known good signature.

Having tested the internal logic, the off-module drivers and receivers and a majority of the module I/O must now be tested. This is accomplished by scanning an alternating one-zero pattern into the boundary scan path. The module output drivers are gated ON allowing the data in the boundary output shift register latches (SRL's) to propagate to the card wiring nets and the results captured by the tester and compared to the correct expect values. In similar manner, the complement of the value stored in the boundary input SRL's is applied to the input of the module and these signals are gated to the input SRL's. If all of t...