Enhancement of micro hole wetting and hydrogen bubble release in the process of Ni micro electroforming under megasonic field

Abstract

Micro hole wetting and hydrogen bubble release are two technical issues in the process of micro hole electroforming. A novel method of megasonic (1.7 MHz) field was introduced in order to solve the two problems and fabricate 20 μm micro column array in this paper. Micro electroforming experiments, capillary tube experiments, electrochemical experiments and testing of contact angle and surface tension coefficient were conducted without and with megasonic field. Experimental results indicated that megasonic field can promote micro hole wetting and bubbles release in the process of micro electroforming. 20 μm micro column array can be fabricated successfully under 2 W/cm2 megasonic field. Because megasonic can decrease the contact angle between photoresist and electroforming solution, reduce the surface tension coefficient of electroforming solution and increase equilibrium potential of nickel. New mechanisms on enhancement of micro hole wetting and bubble release under megasonic field were revealed. The research provides a new comprehension of micro hole wetting and bubble release, which may be good for develop a new method to fabricate micro column array.