An overview of packaging and characterization results of pixel multichip modules at Fermilab

At Fermilab, there is an ongoing pixel detector R&D effort for high energy physics with the objective of developing high performance vertex detectors suitable for the next generation of HEP experiments. The pixel module presented here is a direct result of work undertaken for the cancelled BTeV experiment. It is a very mature piece of hardware, having many characteristics of high performance, low mass and radiation hardness driven by the requirements of the BTeV experiment. The detector presented in this paper consists of three basic devices; the readout integrated circuit (IC) FPIX2A, the pixel sensor (TESLA p-spray) and the high density interconnect (HDI) flex circuit that is capable of supporting eight readout ICs. The characterization of the pixel multichip module prototype as well as the baseline design of the eight-chip pixel module and its capabilities are presented. The PCI test adapter (PTA) card used to characterize the pixel module prototypes is also presented. These prototypes were characterized for threshold and noise dispersion. The bump-bonds of the pixel module were examined using an X-ray inspection system. Furthermore, the connectivity of the bump-bonds was tested using a radioactive source (⁹⁰Sr), while the absolute calibration of the modules was achieved using an X-ray source. This paper provides a view of the integration of the three components that together comprise the pixel multichip module