Experimental results on jet and laser‐jet electrochemical micromachining of nickel and steel in neutral solutions of sodium chloride and sodium nitrate are reported. In the absence of a laser beam, a nitrate solution is better suited for micromachining at high current densities, since it yields high machining rates and relatively low overcutting. In the presence of a laser beam, however, nitrate solution is found to be unsuitable for micromachining, since oxygen evolution is the dominant anodic reaction even at high current densities. In chloride solution, on the other hand, metal dissolution reaction is independent of laser power, but the laser beam helps in focusing the applied current into the machining area thereby increasing the effective machining rate and precision.
Experimental results for a new plating technique using a laser in combination with a pressurized jet are described. Electrochemical and hydrodynamic parameters affecting the gold deposits are discussed. Scanning electron micrographs of the deposited gold surfaces indicate increased smoothness and decreased nodularity as well as disappearance of voids with increasing laser power density. A marked decrease in voids with increasing laser power is also observed in cross‐sectioned samples. At the highest laser power densities used, with a 0.5 mm diam nozzle, plating rates of up to 12 μm/s have been observed. In general, the rate increases with increasing laser power density. Measurements of the Knoop hardness of the deposits gave values in the range characteristic for soft gold.
We describe a metal deposition technique that combines free-standing jet plating with an intense laser beam, directed collinearly along the jet. Experiments were made to deposit gold areas on nick-plated beryllium-copper substrates. The deposits are found to be crack-free and dense, possessing excellent adhesion to the substrate. Deposition rates for 0.05-cm-diam gold spots are on the order of 10 μm/s, faster than any previously reported rate for gold plating.
The laser-jet electroplating technique has been applied to the high-speed deposition of copper at rates up to 50 μm/s. The high plating efficiency of the Cu/Cu++ system makes the deposition rate independent of laser power (unlike that of gold). On the other hand, the morphology of the copper is greatly improved with increasing laser power. Four-point probe measurements for laser-jet copper depositions indicate a resistivity close to that of the published bulk value.
We describe a new type of jet plating that uses a focused high-frequency sound field directed through the center of the jet. The acoustic jet results in an improved morphology for gold and copper depositions although plating rates are not enhanced. Four-point probe measurements of acoustic-jet plated copper lines show up to a 50% decrease in electrical resistivity compared to jet plated deposits.
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