Reliability of pixellated CZT detector modules used for medical imaging and homeland security

Abstract

Long term reliability is critical for a detector module to be used in applications that can not afford failure and require high accuracy such as medical imaging and homeland security. In this study, we report the reliability of pixellated Cadmium Zinc Telluride (CZT) detector modules fabricated from crystals grown by the Traveling Heater Method (THM). The reliability of the module which consists of the pixellated detector assembled to a PCB carrier board via conductive epoxy was studied with both a Quantitative Accelerated Life Test (QALT) as well as the Highly Accelerated Stress Test (HAST) which is a common form of a Qualitative Accelerated Life test. The robustness of the THM pixellated CZT detector modules is demonstrated via the pre-and post-accelerated life test comparison of the leakage current and the spectral performance of the assembled module. A shear test was also used to ensure the adhesion strength of the epoxy bonded method. To our knowledge, this type of study on pixellated CZT detector module has been very rare if not the first of its kind.

Performance of CdZnTe pixellated radiation detectors assembled by a new attachment method

“…Gold stud bonding with polymer epoxy, and indium or other metal bump bonding techniques achieved fine pitch interconnection between pixellated CZT detectors and read out carrier board with application specific integrated chips (ASIC) [6][7][8]. Polymer flip chip and low temperature soldering technologies were used for detectors with moderate size pixel patterns [9][10][11][12]. Each method had its advantages and limitations.…”

“…Due to sensitive physical and electrical properties of CZT materials and to varieties of detector dimensions and anode pixel patterns, attachment of pixellated detectors to readout print circuit boards (PCB) is a field required further research. Studies had been made by a couple of groups on various attachment technologies for CZT or related materials [6][7][8][9][10][11][12]. Gold stud bonding with polymer epoxy, and indium or other metal bump bonding techniques achieved fine pitch interconnection between pixellated CZT detectors and read out carrier board with application specific integrated chips (ASIC) [6][7][8].…”