Thermal and ultrasonic bonding between planar polyethylene terephthalate, acrylonitrile butadiene styrene, and polycarbonate substrates

Polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), and polycarbonate (PC) have seldom been used as substrate materials in chemical and biochips. Here, identical planar PET, ABS, or PC substrates with a thickness of 1 mm were bonded thermally or ultrasonically. Thermal bonding conditions were found by increasing the experimental temperature above the glass transition temperature (T-g) of each polymer. The temperature of each bonding interface should reach T-g. Ultrasonic bonding was achieved when a longitudinal wave of ultrasonic vibration was changed efficiently to friction heat between the bonding interfaces. This phenomenon was promoted by attaching one of the polymer substrates to the ultrasonic horn by vacuum chucking. Using the developed bonding method, the bonding strength that was obtained was approximately ten times the maximum value reported previously. As choices for the substrate material of polymer chips increase, the experimental environments that can be realized in chips will greatly expand.