Contact assembly

Abstract

Abstract A contact assembly for limiting the transfer-current density in a rotary-type plating apparatus for electroplating a metal onto one side of a moving sheet is disclosed. The contact assembly has a contact member on the periphery of the rotatable member of the plating apparatus, which contact member is engageable with the unplated side of the sheet during the path of movement of the sheet through the electrolyte and makes electrical contact with the sheet. The contact member has a contact edge. Sealing means are adjacent the contact member on the rotatable member for receiving an outer edge of the sheet and for sealing the unplated side of the sheet from the electrolyte and for maintaining the cumulative plating current in the sheet and for guiding the cumulative plating current toward the contact member. The sealing member has a sealing edge in sealing engagement with the contact edge of the contact member, thereby forming a contact assembly seal. The contact member has a reduced portion adjacent the end of the contact assembly seal adjacent the contact edge. The reduced portion has a high resistance and a low conductance so that a portion of the cumulative plating current is carried by the reduced portion and the remainder of the cumulating plating current is carried by the sheet so that the transfer current density in the reduced portion is below the hot-spot-producing level in the sheet and below the pickled-band-producing level in the reduced portion. The contact member also has a substantially full portion adjacent the other end of the contact assembly seal. The full portion has a lower resistance than the resistance of the reduced portion and a higher conductance than the conductance of the reduced portion so that the transfer current adjacent the full portion is substantially the residual cumulative plating current in the sheet. The contact member also has an intermediate portion intermediate the reduced portion and the full portion for increasing the transfer current density into the contact member between the reduced portion and the full portion.

Inventors

• 👤 Daniel T Carter

Bibliographic Details