New directions in loaded board testing

The author discusses some of the advances in computer technology that have made possible new techniques for loaded board testing. Two entirely new measurement techniques are discussed, both based on advanced computer technology and both suitable for implementation in a second-generation MDA (manufacturing defects analyzer) instrument. These techniques are mathematical guarding and passive chip diagnosis. Mathematical guarding replaces the per-test-point costs of hardware and extensive programming with computer algorithms and computational power. Passive chip diagnosis replaces backdriving, extensive libraries, and programming effort with an expert system. It is concluded that these techniques offer the possibility of constructing a tester which combines all the valuable attributes of the best in-circuit testers with the low cost and minimal programming requirements of simple MDAs. As a bonus, the new tester is compatible with universal grid, low-cost tooling