US 4,616,596 AGranted

Electroless plating apparatus

AssigneeHughes Aircraft Company

InventorsCarlyle L. Helber, Jr., Frank A. Ludwig

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Abstract

An apparatus for use in electroless plating wherein the activity of the plating solution is controlled by regulating the oxygen content of the plating solution. The apparatus includes an outer container in which the stabilized, oxygen-rich plating solution is stored. An oxygen sparger is located in the outer container to introduce a predetermined amount of oxygen into the plating solution to stabilize it. A flux container and plating vessel are located inside the outer container and define a separate flux zone and a separate plating zone, respectively, through which the plating solution is passed. A nitrogen sparger is located within the flux container to purge all or some oxygen from the stabilized plating solution to provide an active plating solution. The active plating solution is passed from the flux container into the plating vessel where plating of the substrate takes place. Active plating solution continually flows from the plating vessel back to the oxygen-rich reservoir for oxygenation and storage prior to recycling back through the flux container and plating vessel.

Claims11

Dependent claims

An apparatus adapted for use in electroless plating wherein a metal is autocatalytically plated from an electroless plating solution onto a plating surface by a process in which the activity of the plating solution is regulated by the amount of a first predetermined gas dissolved in the plating solution, which comprises:

(a) an outer container having a top, a bottom, and side walls defining a reservoir for plating solution rich in said first predetermined gas;
(b) first sparger means for introducing said first gas into said reservoir in a sufficient amount to provide a predetermined level of said first gas in the electroless plating solution in said reservoir, to produce a stabilized plating solution;
(c) a flux container located inside said outer container, said flux container having a top, a bottom, and side walls defining a flux zone which is separate from said reservoir;
(d) means for transferring stabilized plating solution from said reservoir to said flux zone;
(e) second sparger means associated with said flux zone for introducing a second predetermined gas into said flux zone to reduce the amount of said first gas in said stabilized plating solution to a level sufficient to produce active electroless plating solution;
(f) a plating vessel located inside said outer container, said plating vessel having a top, a bottom, and side walls defining a plating zone which is separate from said reservoir;
(g) means for transferring active electroless plating solution from said flux zone to said plating zone for plating of metal onto the plating surface which is placed within said plating zone;
and
(h) means for transferring active electroless plating solution from said plating zone to said reservoir.

6 more elements

Dependencies are inferred from the claim text.