May be a connector or test posts. Probe manufacturers have developed probe styles to meet the need of these different targets. Much of the front-end work of preparing to build a finished fixture involves ensuring each net can be accessed. This must be done either by the test engineer or the fixture vendor. The target is too small for reliable access.
Target is too close to other points.
This method may tend to reduce the life of the probes due to wear and contamination. In this technique a probe in the probe plate actuates a probe in the diaphragm plate. This reduces the tolerances of the probe plate probes and socket. Another concern in accessing the nets of the UUT is the common use of no-clean flux and other possible contaminants. The probe manufacturers have addressed this problem and there are several probe styles specifically designed to cut through no-clean flux.