Abstract: A test apparatus for testing electronic integrated circuitry, a test probe assembly for use in the apparatus, and a method of forming the test probe assembly are provided. The test apparatus subjects electronic integrated circuitry under test to changing temperatures while communicating test signals from external test equipment to the circuitry under test and back to the test equipment. The test probe assembly used in the apparatus is adapted to expand and contract along with the electronic integrated circuitry as the probe assembly and the integrated circuitry are heated and subsequently allowed to cool during testing, thereby maintaining precise alignment of probes on the probe assembly with test contact points on the electronic integrated circuitry.