Electrochemical etching of shape memory alloy using new electrolyte solutions

This paper presents electrochemical etching characteristics of shape memory alloy (SMA) using new electrolytes of inorganic salt in alcohol, in comparison with conventional H₂SO₄-methanol solution. Pattern etching of SMA sheets could be carried out in the electrolyte solutions using LiCl and NH₄Cl. Especially in the case of the 1mol/l LiCl -ethanol, good etching properties such as controllable low etch rate, uniform etching depth and flat etched surface were obtained. The etch factor (=etching depth/side etching width) was 1.5 in 1mol/l LiCl-ethanol and 2.0 in 0.1mol/l LiCl-ethanol. Throughout etching could be carried out by using a backside dummy metal. This etching technique has been applied to the micromachining of SMA sheet and SMA pipe for fabrication of actuators.