Reducing probe card substrate warpage

A probe card for testing an integrated circuit having electrical contacts, the apparatus comprising:

• a. an interface member for connecting the probe card to a test station,
• b. an electrically non conducting substrate having a first side and an opposing second side, and electrically conducting traces,
• c. a plurality of electrically conducting probes disposed adjacent the second side of the substrate, the probes making electrical connections with thetraces, the probes for making forceful contact and electrical connection with the electrical contacts of the integrated circuit,
• d. electrically conducting members disposed between the first side of the substrate and the interface member, the electrically conducting members making electrical connection between the traces of the substrate and the interface member, the electrically conducting members disposed such that at least one void is formed between the first side of the substrate and the interface member, where at least a portion of the at least one void is disposed substantially opposite the probes, and
• e. an electrically non conducting material disposed within the at least one void so as to substantially fill the at least one void and to reinforce the substrate against deformation during testing of the integrated circuit when forceful contact is made between the probes and the electrical contacts of the integrated circuit.