2021 年 72 巻 2 号 p. 110-116
Recently, microfabrication of Cu wiring on printed circuit boards（PCBs）has advanced because of demand for the miniaturization and advancement of electronic devices. In the case of plating Ni（over 5 μm）/Pd/Au on PCB using conventional electroless Ni/Pd/Au plating processes, Ni deposition tends to occur outside of the Cu pattern. To resolve this difficulty, a Ni（under 1 μm）/Pd/Au film is plated on a fine Cu pattern. However, few reports have described the study of various surface mounting characteristics on the Ni（0.1 μm）/Pd/Au plating process. Therefore, we specifically assess the relations among various surface mounting characteristics and Ni film thickness（0.01-5 μm）on electroless Ni/Pd/Au plating. We obtained the following conclusions as a result of various observations. Ni film thickness under 0.05 μm is necessary to suppress the Ni deposition on the outside of the Cu pattern. However, Ni film thickness of greater than 0.1 μm is necessary to obtain good solder ball mounting characteristics. Also, Ni film thickness over 0.3 μm is necessary to obtain stable wire bonding characteristics.
