US 4,379,031 AGranted

Evaporation driven counterflow rinse system and method

AssigneeImperial Clevite Inc.

InventorsJames A. Krotkiewicz, Wayne A. Kruper, Otto C. Niederer

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Abstract

An electroplating apparatus comprises a plating tank, first, intermediate, and final rinse tanks, and a plurality of weirs which connect the plating tank and the first rinse tank, the first and intermediate rinse tanks, and the intermediate and final rinse tanks. The plating tank is filled to a predetermined level with a plating solution including plating chemicals and water. The rinse tanks are each filled to the predetermined level with rinse solution including water and plating chemicals which have been rinsed from preceding workpieces. The final rinse tank has an overflow outlet at the predetermined level and receives a continuous flow of water. As water evaporates from the plating tank, rinse solution flows by gravity through the connecting weir to the plating tank to replace it. Similarly, rinse solution flows by gravity through the connecting weir from the intermediate rinse tank to the first rinse tank and flows by gravity through the connecting weir from the final rinse tank to the intermediate rinse tank. The continuous flow of water into the final rinse tank replaces the solution flowing by gravity to the intermediate rinse tank thus maintaining the plating and rinse tanks at the predetermined level. To prevent plating chemicals from migrating from more concentrated solutions to less concentrated solutions, baffles are placed in each of the weirs. The baffles render the flow paths sufficiently long and tortuous so that the evaporation replacing flow offsets the migration of plating chemicals toward less concentrated solutions.

An electroplating apparatus comprising:

a plating tank for receiving a plating solution including plating chemicals and water to a predetermined fluid level in which a selected number of workpieces on a supporting structure are submersed and plated, the plating solution level being diminished by evaporation;
a first rinse tank for receiving rinsing solution to said predetermined level, the first rinse tank being disposed sufficiently adjacent the plating tank to enable plated workpieces to be submersed in the first rinse tank solution to rinse the plating solution from the plated workpieces, whereby the rinsing solution in the first rinse tank includes water and the plating chemicals rinsed from preceding workpieces;
a first elongated fluid path interconnecting the plating tank and the first rinsing tank, the first fluid path being disposed at or below said predetermined level such that solution flows by gravity from the first rinsing tank to the plating tank to replace evaporated plating solution, whereby plating chemicals are returned to the plating tank, with said first fluid path including a plurality of baffles therein to prevent fluid from flowing directly therethrough;
a final rinse tank for receiving rinsing solution to said predetermined level, the final rinse tank being disposed sufficiently adjacent the first rinse tank to enable the rinsed workpieces to be submersed in the final rinse tank solution to rinse the plated workpieces further, whereby the rinsing solution in the final rinse tank includes water and the plating chemicals rinsed from preceding workpieces;
a second elongated fluid path in fluid connection with the first and final rinse tanks, the second fluid path being disposed at or below said predetermined level such that solution flows by gravity from the final rinse tank to the first rinse tank with said second fluid path including a plurality of baffles therein to prevent fluid from flowing directly therethrough;
and
level maintaining means operatively connected with the final rinse tank for maintaining the rinsing solution in the final rinse tank at said predetermined level, whereby the solutions in the first rinse tank, final rinse tank and the plating tank are maintained at said predetermined level and plating chemicals are returned from the final rinse tank to the first rinse tank and from the first rinse tank to the plating tank.

4 more elements

Abstract

Claims13