Adaptive pressure ultrasonic precise bonding method for polymer micro joint

Ultrasonic precise bonding for polymer micro joint was studied. Considering shape deviation as the key issue to successful micro bonding, an ultrasonic bonding system was established, which employed 60 kHz ultrasonic transducer that achieved bonding at low amplitude. Adaptive ultrasonic bonding with bonding energy auto-selected was proposed. In this method, continues decreasing pressure was imposed on the micro components, the heat was accumulated and when the interface reached the melting point of the polymer, the pressure skip detected by the sensor and treated as the signal to turn off the ultrasonic vibration by the system. Polymer mechanical behavior was the control parameter in this method, precise energy for each component was auto-selected by system, and this solved the problem of surface roughness deviation form micro component and made small deformation of microstructure. Based on this method, linear guide was chosen to drive the ultrasonic horn. A kind of micro pump seat was bonded by this system. The joint had a transparent bonding interface and shear strength of 8 MPa which met the demand of MEMS. The interfacial temperature was measured during bonding. The influence of bonding pressure to the bonding quality was obtained. The result is contributed to ultrasonic bonding process optimizing and system design.