Adhesion Enhancement of a Plated Copper Layer on an AIN Substrate Using a Chemical Grafting Process at Room Temperature

AIN substrates have been extensively used for heat dissipation, especially in high-power light-emitting diodes (LEDs). However, the AIN substrate is an electric insulator and thus needs to be metalized to serve as an electric circuit carrier and heat conductor for LED packaging. Herein, we propose a wet process that can be performed at room temperature to metallize AIN substrates. The wet metallization process involves copper electroless deposition and copper electroplating. The catalyst used for the copper electroless deposition was PdCl2, which was chemically grafted onto the AIN surface. The chemical grafting agent was 3-(2-aminoethylamino)propyltrimethoxysilane (APTMS). Before the chemical grafting step, an etching step in KOH solution was critical for good adhesion of the plated copper layer. The electroless copper depositions were catalyzed using chemically grafted Pd and a commercial Sn/Pd colloid. An adhesion comparison test of the plated copper layers was performed to demonstrate that the copper adhesion performance obtained with the chemically grafted Pd process was substantially better than that obtained with the commercial Sn/Pd colloid process. (C) 2014 The Electrochemical Society. All rights reserved.