On-Line Electroplating Thickness Monitor

A new instrumental technique has been developed that measures the thickness of electroplating as an on-line process parameter.

The technique is based on the precise determination of the resistance of the electroplated deposit on a stainless steel wire sensor. Using the resistivity of the plated metal as a calibration factor and knowing the precise dimensions of the deposit permits the determination of the thickness in microinches based on the resistance of the deposit. The unique sensor configuration combined with the capabilities of the microprocessor-based instrument permit measurements to be made on-line, in the bath, at plating currents in excess of 100 amps/square foot. The measurement spans range from approximately 5 to 3,000 microinches for metals with resistivities ranging from 1.6 to 150 microhm-cm.

Laboratory and field testing of the technique is described, and data presented, for nickel, copper and gold.