Challenges of Packaging Cd-Zn-Te (CZT) Detectors

ABSTRACT Cd-Zn-Te (CZT) is a compound semiconductor used for radiation detection, which directly converts X-ray or gamma ray photons into electrons. CZT is relatively brittle and prone to cracking under mechanical stress. Improvements are demonstrated to the ruggedness and reliability of CZT detector technology using advanced packaging and assembly technologies by controlling the stress in the CZT crystal adjacent to the interconnection that joins the crystal to the substrate. Finite element modeling (FEM) and experimental measurements have been conducted to quantify the amount of stress that a CZT crystal can withstand prior to cracking. From this work it was determined that the critical stress region to initiate cracking in CZT occurs in the range of 18-50 MPa. Two new interconnect configurations were evaluated: A polymer ball and tall epoxy interconnect both produced stresses well below this range when subjected to thermal cycling (80-22°C) and 1000g drop shock loads.