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Under an ESA contract, Leonardo UK developed the IBEX detector also referred to as LAPD for Large-format Avalanche Photo Diode array. Leonardo’s packaging solution relied on a chip-on-board solution incompatible with technical and performance requirements of ESA characterization campaign and experimental setup. An in-house solution has been developed, with ESA responsible for the design, manufacture, and test. And Leonardo responsible for gluing the device to the carrier and the wire bonding. ESA’s packaging solution relies on molybdenum carrier and two flexible PCB cables. The design, manufacturing, testing, and assembling of the various components of the LAPD package assembly entailed a variety of design iterations, tests, and trials. The material choice was a compromise between optimal CTE mismatch of Invar 36 and excellent thermal conductivity of TZM molybdenum (TZM = 0.5% titanium, 0.08% zirconium, 0.02% carbon). TZM molybdenum was chosen, and it was decided to verify the behavior by test. A thermal-vacuum test campaign showed that a mounted ROIC survives test representative conditions i.e., various thermal cycles between 20 and 200K. The gold coating of the molybdenum carrier is a real challenge, we will report on lessons learned. Similarly, the flexible PCB cables gluing to the carrier performed in-house is a delicate exercise. The flex cables are bonded to molybdenum blocks which are permanently mounted in a recess in the back of the carrier. Several trials were done for the mounting until successful result was reached. A sequence of thermal cycles between 20 and 200K were performed and showed no evidence of failure throughout the bond line between the block and flex cable. A handling jig was designed to fit Leonardo’s bonding setups for the die mounting and wire bonding. The handling jig is also used to safely mount the device in an in-house designed transportation and storage container.
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