Study of Printed Circuit Board's Inspecting System

The digital technology contributes to the reduction in size of equipment such as mobile phones and personal computers. Accordingly, the advancement in the production of printed wiring boards is also remarkable. Presently, the inspection of printed wiring boards includes the conductivity, the capacitance, the appearance inspections, and so forth. There are problems of the conduction defects, the effect of the stray capacitance and the mistaken image in these inspections. In order to resolve these problems, in our research a pin probe with a dielectric substance is produced, a serial resonance circuit is constructed in a manner that the spacing between the electrodes of the probe and those of the wiring board is regarded as a condenser, and an inspection system is developed which can determine the connection, insulation, short-circuiting and disconnection by measuring the magnitude of resonance current value. Usability of this scheme is verified after the check test has been conducted using a wiring board such as BGA and PWB.