Test Equipment for CMOS Lead Open Detection Based on Supply Current under AC Electric Field Application

摘要

Open leads have often occurred in logic circuits implemented on printed circuit boards with the state-of-art technology. We proposed an electrical test method to detect them with high fault coverage. The test method is based on supply current change of a circuit under test that is caused with AC electric field supplied from the outside of the circuit. In this paper, we propose a test equipment for the test method. A voltage signal that is obtained by mixing a rectangle waveform signal and a sine waveform one is supplied between electrodes to generate the electric field. Amplitude of the signal continues to increase in proportion to time during a specified time. When supply current change that is larger than a threshold value appears, it stops increasing the amplitude and it is concluded that open leads occur in the circuit. If the supply current change does not appear within the specified time, it is concluded that no open leads occur in the circuit. In this paper, it is shown experimentally that an open lead at a CPLD of PLCC package is detected with the test equipment.