Efficient screening of through-silicon-via (TSV) ASICs for CZT x-ray imaging detectors (Conference Presentation)

The High Resolution Energetic X-ray Imager (HREXI) is a coded-aperture imaging telescope that utilizes tiled CdZnTe (CZT) detectors to image cosmic x-ray sources and transients in the 3-200 keV energy band. A closely tiled array of 256 pixellated CZT detectors form the 1024 cm^2 detector plane of a proposed (Grindlay et al. 2019) SmallSat mission. This close tiling of the crystal units is achieved by Through-Silicon-Via (TSV) enabled readout ASICs that shrink the readout electronics footprint of the wire-bonded ASICs previously developed and incorporated on the Nuclear Spectroscopic Telescope Array (NuSTAR) mission. To close-tile large numbers of detectors, an efficient die-level ASIC screening method is required for the TSV-ASICs. The ASIC Test Stand (ATS) was developed (Violette et al. 2018, SPIE Proceedings) in order to enable rapid testing of die-level TSV-ASICs by precision alignment of a fixed array of spring-loaded pogo-pin probes to connect to the ASIC's 87 pads with a 225 micron pitch. Here we report ATS design improvements and results from testing ASIC energy resolution and stability using the commandable test pulser internal to the ASIC. Multiple ATS systems will enable rapid testing and selection of ASICs for large area detector arrays as needed for the HREXI SmallSat Prototype (HSP).