LAUSR

A new method for liquid-phase bonding of copper plates to an aluminum nitride (AlN) substrate was developed in this work. A newly developed proprietary interlayer composed of titanium and silver powders was deposited on the AlN substrate using a screen-printing machine. The eutectic reaction between printed silver and copper at 850 °C led to formation of a liquid phase at the joint interface. A total of 42 samples were prepared using seven and six different amounts of silver and titanium, respectively. The microstructures of all samples were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy, and an ultrasonic flaw detector was used to assess joint integrity. The optimum composition of the Ti–Ag brazing alloy for producing defect-free joints was determined. The formation of a continuous titanium nitride layer was found to be essential for achieving sound joints between the copper plates and AlN substrate.