Influence of Complexing Agents on Adhesion Strength of Electroless Nickel–Phosphorus Plating to Silicon Nitride–Aluminum–Polyimide Mixed Substrates

Abstract

The adhesion force of electroless nickel–phosphorus (Ni–P) platings prepared on silicon nitride (SiN), aluminum (Al), and polyimide (PI) substrates using complexing agents of glycine, succinic acid, succinic acid with glycine, and succinic acid with malic acid was demonstrated for the application to wafer-level packaging in large-scale integrated circuits. The adhesion strength of Ni–P platings was investigated by the tape-peeling test and the universal mechanical strength tester. As results, no peeling of Ni–P films formed using glycine, succinic acid, and succinic acid with glycine were observed, although Ni–P films formed using succinic acid with malic acid showed peeling. Thus, Ni–P plating formed using succinic acid with malic acid gave the smallest adhesion force. In contrast, the adhesion force of Ni–P platings formed using succinic acid with glycine on SiN, Al, and PI was the largest, approximately 850 kg cm−2, among Ni–P platings formed using those complexing agents. The growth rate of Ni–P films formed using succinic acid, succinic acid with glycine, and succinic acid with malic acid was uneven on SiN, Al, and PI. In comparison, Ni–P plating formed using glycine provided uniform growth rate on SiN, Al, and PI.

Polyimide Metallization Using Nickel Nano-Film as both Catalyst and Barrier Layer of Copper Electroless Deposition

“…A dry process, such as metal sputtering, combining with a wet process, such as electroless deposition and then electroplating, is the most popular process now, because the adhesion strength between the metal layer and the PI film is critical. 9,[22][23][24][25][26][27][28][29] Various surface modification approaches of PI were proposed, including dry [29][30][31][32][33][34][35][36][37][38][39][40] and wet 1,4,15,30,36,[40][41][42][43][44][45][46][47][48][49] processes. However, when one considers the process, tools cost, through put, reliability and so on together, it seems difficult to obtain an overall perfect process to achieve the PI surface metallization with a layer of thin copper foil without roughness in between because of the requirement of fine lines and high frequency transmission.…”