Development of advanced test algorithm for in-circuit test systems

Abstract

In-Circuit Test Systems (ICTs) are automatic equipments that tests soldered PCB subsystems. They detect target PCBs`` failures such as wrong components, missing components, wrong polarity, and so on. The purpose of this thesis is to develop advanced test algorithm for In-Circuit Test Systems. Conventional ICTs have several limitations in their own. In hardware structure, the measuring part is separated in 2 subparts as DC measurement and AC measurement. DC measurement part can only produce predefined level of voltage in unipolar manner - it cannot operate in bipolar. Test signal from AC measurement part has limited frequency which limits testable range. With these hardware constraints, conventional ICTs`` can test target PCBs in restricted manner. Newly developed measuring part is integrated in one board. It can produce not only DC signal but also AC signal. Moreover, it can generate ANY type of test signal we want by using dual-port RAM and digital-to-analog converter. With this feature, we can use triangular and rectangular waveforms in addition to simple DC and AC sine waveforms. Using these additional waveforms as test signal, we show some merits including usefulness in measuring small R, L, and C and satisfaction of initial and final condition for energy-storage components like L and C . We use integrator in noise reduction and can take advantage of it in measuring RLC parallel circuit which is not possible by using conventional ICT. We implemented newly developed test algorithm in hardware and software. New measure board is integrated in one, and controlled by ISA-based PC interface card. We control this card under Windows 2000 using WDM driver and program compiled using Visual C++. Some experiments are performed. They show the realizability and usefulness of developed algorithm.