Nanoceramic Processing for High-Power Multi-channel Electron Multiplier in Low Temperature Cofire Ceramic (LTCC)

Abstract

Nanoceramic processing technologies are brought together with standard LTCC materials to demonstrate a dynode structured electron multiplier with integrated cooling. Process developments include the integration of numerous components, including an embedded passive, high-density interconnect, and high-performance thermal management system. Enhanced processing capabilities utilize nanoparticles to control sintering kinetics. Cofirable thick Ag tapes have been demonstrated that allow multilayer structures to include a thick (up to 0.5mm) solid Ag layer. The development of 3-D cavities using fugitive inserts have produced meso- and micro-scale channels, with X-Y-Z channels of 50 μm diameter demonstrated. Nano-sized MgO, processed using electrophoretic deposition, has been developed for a secondary electron emitter (SEE) with a gain factor of 2.0. To minimize thermal run-away and, subsequently, thermal failure, a positive temperature coefficient (PTC) resistor system compatible with LTCC processing is being developed to reduce supplied power to the individual multiplier structures to control localized heating. In this study the synthesis of nanostructure MgO is shaped by electrophoretic deposition that consists of the deposition of particles at dynodes submerged in a solution of magnesium methoxide. Charged particles of MgO are suspended in the solution and forced to move toward the dynode (which bears the opposite charge) by applying an electric field, thus forming a thin coating of collected MgO particles on the dynode. Different annealing conditions are used to optimize the microstructure and secondary electron emission (SEE) of the deposited materials.