Bonding fixture tolerances for high-volume metal microlamination based on fin buckling and laminae misalignment behavior

Microlamination involves the patterning, registration and bonding of thin layers of material, called laminae, to produce monolithic devices with embedded micro-scale features. In energy, chemical and biological systems miniaturization, microlamination can be used to produce bulk microfluidic devices for mobile, compact or point-of-use applications. Thermally-Enhanced Edge Registration (TEER) is a registration technique used in metallic microlamination to precisely align laminae during high-temperature bonding cycles. Shape variation, such as channel misalignment or fin buckling, incurred during the TEER registration step can lead to lower system performance or even functional failure. This paper investigates the allowable tolerance limits in TEER fixtures in order to minimize fin buckling while attaining precise alignment. A high-temperature buckling model is developed to predict the onset of fin buckling within a TEER fixture. The results of the model are validated empirically. Results indicate that within the tolerance limits, micrometer-scale channel-to-channel alignment can be achieved free of fin buckling. In addition, the general relationship between the critical point of buckling and the device configuration is discussed for broader application.