Application of Controlled Thermal Expansion in Microlamination for the Economical Production of Bulk Microchannel Systems

Diffusion bonding has been widely used within microlamination architectures for the fabrication of Micro Energy and Chemical Systems (MECS). MECS are microsystems with the ability to process bulk amounts of fluid within highly-parallel microchannel arrays capable of accelerated heat and mass transfer. Thus far, diffusion bonding of the microchannel arrays is commonly done in a vacuum hot press system. The use of the hot press greatly restricts the production rate due to vacuum pump-down time and heating-up and cool-down periods. Furthermore, larger substrates are gaining interest in the system design of MECS devices and it is not apparent that uniaxial pressing within a hydraulic vacuum hot press will provide the bonding pressure uniformity necessary for large substrate bonding. This paper presents a novel fabrication approach for the high-volume thermal bonding of MECS devices with the use of controlled thermal expansion. A thermal bonding fixture based on the principle of differential thermal expansion was developed with focus on controlling the bonding pressure magnitude, the pressure timing and its sensitivity. The application of such a fixture within a conveyorized furnace system could be the key to a continuous thermal bonding approach for the mass production of MECS devices.