per square foot however depending upon the particular circumstances these general parameters may be changed generally this plating would be about 0 010 inches but could be thinner or thicker as noted above this particular plating is not used for the circuit on the surface and thus the limitations on plating would be determined by the desired wall thickness for the probes produced in accordance with this process when holes of about 0 016 inches in diameter are utilized and surface plating to 0 010 inches is utilized the plating on the wall surfaces 40 is usualy 0 007 inches that is the structure produces a cylinder having a central hollow core of about 0 002 inches in diameter this limitation is a result of a concentration gradient in the copper sulfate solution and the very low availability of the copper sulfate for plating when the hole becomes very small thus plating can be continued until the appropriate streng this obtained in the walls of the eventual probes as the thickness of the plating on the surfaces 36 and 38 does not contribute to or control the eventual circuit characteristics after removal from the plating bath the structure shown in fig4 is dried and then surface layers 36 and 38 are removed for example by.