Enhancing the Adhesion Strength Between Cu Substrate and Ni Layer in Microelectroforming

Many electroforming microstructures need their substrates to be bonded with electroforming layers in micromanufacturing. A controlling current density method to improve the adhesion performance of the copper substrate to the nickel electroforming layer was presented. Lower direct current density was employed to activate the substrate. A scratch test was conducted to evaluate the adhesion strength quantitatively by observing the friction load versus the normal load and the scratch track using a digital microscope. The experimental results indicated that electrochemical activation occurred on the cathode surface with an initial current density of between 0.2 and 1.0A/dm(2). The adhesion performance of the activated substrate to the nickel layer was higher than that of a substrate without activation. While the direct current density was 0.4A/dm(2), the adhesion strength was the highest. Electrochemical activation at the beginning of microelectroforming can enhance the adhesion strength of microstructures.