Basic Research on the Metallization of Aluminum Pads, Silicon Nitride and Polyimid by Electroless Nickel-Phosphorus Plating

Abstract

The metallization of aluminum (Al), silicon nitride (SiN) and polyimide (PI) have been investigated by changing the activation method necessary to start electroless plating. The adhesion force between the substrate materials and the following electroless Ni–P plating film is investigated. A one-solution type activation method is too acidic for Al and a zincate process is necessary for metallization. The polyimide substrate showed enough adhesion force for tape peel test. The silicon nitride substrate is difficult to plate uniformly. To increase the adsorption of the Pd catalyst, a conditioning process is effective for the SiN substrate. For one-solution type activation, the zincate process is necessary for the Al substrate and the conditioning process is necessary for the SiN substrate. A two-solution type activation method is available for all substrates and three repetitions are necessary for the SiN substrate. The adhesion force between the plated film and substrates is quantified. The highest value was obtained for the Al substrate after the zincate process, and the lowest value was obtained for the SiN substrate after two-solution type activation. Sufficient adhesion force, over 600 kg/cm 2 , was obtained for all substrates with the two-solution type activation method. Therefore, the two-solution method shows high