| 摘要 |
A testing device for testing the quality of through-hole plating of a printed circuit board employs probes having pyramidical tips, with the edges of the probe tips contacting the ends of the through-hole plating. The probe edges are insulated from each other, so that the device can easily carry out Kelvin four-point testing. Because contact is needed only at the probe edges, lighter force can be applied to the probes, and plating damage can be avoided. The device also is constructed to avoid interference from stray varying magnetic fields. This is done by keeping the area of a voltage loop between the probes as small as possible, by use of ferromagnetic members to divert stray fields to the outside of the loop, and by use of a dual-slope integrating digital to analog converter.
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