Fabrication Study of a LED Thermosonic Flip Chip Bonding Apparatus

The current light-emitting diodes (LED) flip chip has the advantage of high speed electricity, small volume, good heat dissipation and high I/O density for modern display technology. Thermosonic bonding system for LED seeking to feature with lower temperature and lower pressure for industrial application is overwhelming. Development of such potential precision, fine pitch and with shorten ultrasonic time for manufacturing process is studied in this paper. This apparatus consists of (1). a mechanism system comprised with the precise positioning, loading and unloading stages, (2) control system for chip placement and visualization of LED, (3) the flip chip bonding head module consisted with ultrasonic bolt-clamped Langevin type transducer (piezo actuator), horn device and tool for chip and substrate compression, and (4) a chip vacuum head is design for the bettering bonding processing. Experiments results with consideration of temperature, pressure, ultrasonic power and ultrasonic time are conducted by using Taguchi method for optimization. Results show the in laboratory developed thermosonic flip chip bonding system can be potentially used for back light module in display technology.