Electrical characterization of a wirebonded TO-39 package for IR radiation detectors

In this paper an approach to modeling of TO-39 packages employed for IR detectors wirebonded to the package leads is discussed. The presented approach is based on measurements of a real package in which the detector chip was replaced with a 2-port of known parameters (a microstrip line of length equall to that of the original chip) and connected to the package leads with wirebonds. In this respect the presented procedure differs from the literature reports, which concentrate mostly on indirect package characterization based solely on full-wave EM models of the packages. The sensitivity of the approach to varying lengths of the wirebonds used to connect the known 2-port to the package is analyzed. To this end, the structure was wirebonded several times. Each time it was measured so that the discrepancy in extracted parameters of the package equivalent circuit could be observed.