Probe card assembly with a mechanically decoupled wiring substrate

A probe card assembly comprising:

• a probe head assembly comprising a plurality of probes disposed to contact an electronic device disposed on a holder in a test housing;
• an electrical interface to a test controller;
• and
• a wiring substrate comprising wiring that forms portions of electrical paths between the electrical interface and the probes, the wiring substrate comprising a first portion that forms a periphery of the wiring substrate and a second portion disposed within the periphery formed by the first portion, wherein the first portion is configured to remain substantially stationary and the second portion is configured to be moveable with respect to the first portion, wherein the electrical paths comprise flexible electrical connections between the first portion and the second portion of the wiring substrate.