Low capacitance probe for testing circuit assembly

摘要

An improved system for capacitive testing electrical connections in a low signal environment. The system includes features that increase sensitivity of a capacitive probe. One feature is a spacer positioned to allow the probe to be partially inserted into the component without contacting the pins. The spacer may be a collar on the probe that contacts the housing of the component, contacts the substrate of the circuit assembly, or both. In some other embodiments, the spacer may be a riser extending beyond the surface of the sense plate that contacts the component, a riser portion of the component, or a combination of both. The spacer improves sensitivity by establishing a small gap between a sense plate of the probe and pins under test without risk of damage to the pins. A second feature is a guard plate of the probe with reduced capacitance to a sense plate of the probe. Reducing capacitance also increases the sensitivity of the probe.

主权项

1. A probe configured to test pins on a circuit assembly, the probe comprising:
a sense plate for receiving signals on the test pins through capacitive coupling; a guard plate, parallel to the sense plate, comprising a plurality of holes sized and positioned to reduce capacitance between the sense plate and the guard plate, the plurality of holes having a total area comprising at least 25% of an area of a guard plate surface through which the plurality of holes are formed; and a dielectric between the guard plate and the sense plate.