Abstract: An electrical connector (10) provides a mechanical coupling and an electrical interface between circuit boards (12,14). An elastomeric electrical conductor (20) provides compressible electrical connector paths between first and second sets of electrical contact pads (28,15) coupled to the respective circuit boards. A compression mounting assembly (22) aligns and retains the elastomeric electrical conductor (20) between the sets of electrical contact pads. The elastomeric electrical conductor (20) affords relatively high frequency signal conducting paths with substantially constant impedance for example for passing test signals and pin signals without distortion between circuit boards in the test head of an IC device tester. A mechanical spring system (64,65) spring loads the compression mounting assembly (22) and provides a relatively high mechanical compliance coupling between circuit boards (12,14) to accommodate relative change of position of the boards due to misalignment or board warpage.