When machining the assembly holes in the Probe-Plate (KTP) it is necessary to differ between the diameter of the drilled hole and the diameter of the actual drill. The sizes in the catalog are related to the diameter of the drilled hole. This size can be measured with a common plug gauge. Depending on the material and the thickness of the probe-plate, the diameter of the drill should be chosen 0.01 – 0.03 mm larger. At the same time, other parameters such as, e.g. drill speed and feed etc. also play an important role. Note: it is vital to carry out drilling tests beforehand.
The materials FR4/G10 (glass-fibre enforced synthetic material) and CEM1/Trolitax (hard-paper impregnated with resin) have proven to be especially suitable as probe-plate materials. Especially in the case of small assembly hole diameters there is an acute danger that the drilled holes become slanted, which leads to the Receptacles and the Test Probes also being slanted when inserted and subsequently results in a negative influence of the contacting accuracy. In this case, INGUN recommends that the assembly holes in probe-plates thicker than > 10 mm are counter-bored from the under-side. Furthermore, drilling the holes in steps is also advisable.