Electroless nickel plating on aluminum substrates using a nickel displacement process has been investigated. A zincate process is generally used prior to electroless nickel plating on aluminum substrates. However, the deposited nickel film exhibits higher adhesion strength if a nickel displacement process is used instead of the zincate process. Adhesion strength depends on the displacement reaction rate which can be controlled by selecting the appropriate complexing agent and plating conditions in the displacement bath. In addition, photoresist can be applied for providing a fine conductive circuit, pad, via-hole, or bump with electroless nickel since the high alkaline zincate process is eliminated. Straight-walled bumps approximately 20 mum wide and 15 mum high can be formed by electroless nickel deposition using the nickel displacement process.