Enhancing signal transmission rate in photon-counting computed tomography detectors

Photon counting detector (PCD) is one of the most important components of medical CT, which has low radiation and high energy conversion efficiency. In the development process of photon detector packaging, CdZnTe (CZT) packaging method is the key research object. At present, CZT and Interposer (IP) are directly interconnected after double-sided printing, which has low connection efficiency and high shedding rate, is no longer applicable to the requirements of the CZT packaging. Therefore, a CZT single-sided dispensing method was innovatively studied in this paper, connecting the CZT after IP were implanted with gold bumps to form a stable CZT-IP-ASIC sandwich structure. Through the measurement of the attaching accuracy after CZT packaging, it is found that the substrate warpage plays an important role in the packaging process. By studying the signal intensity and stability performance generated by different dispensing methods, the optimal dispensing method and low-temperature baking method are selected to lay a theoretical foundation for the subsequent production. In addition, the measurement standards of CZT silver paste dispensing parameters and placement accuracy were formulated, which ultimately achieved a 100% signal reception pass rate. This work provides an effective strategy for CZT crystal placement, which is of great inspiration for the development of packaging for indirect interconnection of photon-counting CT detectors.