Preparation of samples

The layer system Si/Ti/Ti02-X was used as an electrode for the cathodic deposition of nickel. The Si/Ti substrate was supplied by HL-Planar, Dortmund, Germany. It was fabricated by sputtering 3 pm Ti onto a silicon wafer. By a wet chemical oxidation of the Ti layer with H2C>2/NaOH, a porous oxide layer is formed with an approximate thickness of 40 nm which conducts sufficiently to act as the plating base commonly used in the LIGA process. As outlined in detail in [5], the electrochemical deposition of nickel was carried out in a sulfamate bath under potentiostatic control -0.715 V vs. SHE. During deposition, an Hg/Hg2SC>4/0.5 M Na2SC>4 reference electrode was used. The potentials reported in this paper are given with repects to the standard hydrogen electrode (SHE). Recording of current transient and potential control was done with a potentiostat (EG&G Model 273A). The amount of deposited nickel was determined by the charge obtained by integrating the current transient. The electrolyte composition was the typical one used for the electroforming step in the LIGA process: nickel as sulfamate (78 g/1), boric acid (40 g/1), and surfactants. The temperature maintained during deposition was 52°C and the pH was adjusted to 3.6.

0 0

Post a comment