Electroless plating of piezoelectric ceramic

1 . A method of electroless plating lead zirconate titanate (PZT) ceramic with copper metal comprising:

contacting said surface of said PZT ceramic with a sensitizing solution to form a PZT surface sensitized with tin and palladium;

forming a copper electroless plating solution including copper salt;

contacting said copper electroless plating solution with copper halide salt to form a mixture; and

contacting a surface of said PZT ceramic sensitized with tin and palladium with said mixture to form a conductive layer of copper metal on said PZT ceramic surface sensitized with tin and palladium; and wherein:

said step of contacting said copper electroless plating solution with copper halide salt is performed after said step of forming a copper electroless plating solution.

2 . The method of claim 1 , wherein said surface of said PZT ceramic sensitized with tin and palladium is contacted with said mixture for a time sufficient to plate said PZT ceramic surface with said conductive layer of copper metal.

3 . The method of claim 1 , wherein said copper halide salt is cupric fluoride, cuprous fluoride, cupric chloride, cuprous chloride, cupric bromide, cuprous bromide, cupric iodide, cuprous iodide or mixtures thereof.

4 . The method of claim 3 , wherein said copper halide salt is cupric chloride or cuprous chloride.

5 . (canceled)

6 . The method of claim 1 , wherein said copper salt is cupric sulfate or cuprous sulfate.

7 . The method of claim 6 , wherein said copper electroless plating solution further comprises a reducing agent.

8 . The method of claim 1 , wherein said step of contacting said copper electroless plating solution with copper halide salt comprises:

stirring said mixture for a time sufficient to dissolve said copper halide salt.

9 . The method of claim 8 , wherein said time is about 5-20 minutes.

10 . The method of claim 1 , wherein said step of contacting said surface of said PZT ceramic with said mixture comprises:

contacting said surface of said PZT ceramic in said mixture for about 1 minute to about 30 minutes.

11 . The method of claim 1 , further comprising before said step of contacting said surface of said PZT ceramic with said mixture:

cleaning said surface of said PZT ceramic.

12 . The method of claim 1 , further comprising before said step of contacting said surface of said PZT ceramic with said mixture:

wetting said surface of said PZT ceramic.

13 . The method of claim 12 , wherein said wetting step comprises:

contacting said surface of said PZT ceramic with a wetting solution in a vacuum chamber.

14 . The method of claim 13 , wherein said vacuum chamber comprises:

a holding chamber for holding the wetting solution and said PZT ceramic;

a lid for covering and sealing said holding chamber; and

a vacuum inlet valve disposed in said lid for introducing a vacuum into said holding chamber.

15 . The method of claim 1 , wherein said step of contacting said surface of said PZT ceramic with a sensitizing solution to form a PZT surface sensitized with tin and palladium comprises:

contacting said surface of said PZT ceramic with a sensitizing solution comprising aqueous tin chloride.

16 . The method of claim 15 , further comprising after contacting said surface of said PZT ceramic with said sensitizing solution comprising aqueous tin chloride:

contacting said surface of said PZT ceramic with a sensitizing solution comprising palladium chloride to sensitize said PZT surface to copper plating.

17 . The method of claim 16 , further comprising after contacting said surface of said PZT ceramic with said sensitizing solution comprising palladium chloride:

contacting said surface of said PZT ceramic with an accelerator solution comprising nickel hexahydrate.

18 . A method for electroless plating copper metal onto a surface of an array of lead zirconate titanate (PZT) ceramic elements embedded in epoxy, comprising:

contacting a surface of said array of PZT ceramic elements with a sensitizing solution comprising tin chloride;

contacting said surface of said array of PZT ceramic elements with a sensitizing solution comprising aqueous palladium chloride to form a PZT ceramic surface sensitized with tin and palladium;

forming a copper electroless plating solution including a copper sulfate salt;

contacting said copper electroless plating solution with a copper bromide salt to form a mixture; and

contacting said PZT ceramic surface sensitized with tin and palladium with said mixture to form a conductive layer of copper metal on said PZT ceramic surface sensitized with tin and palladium; and wherein:

said step of contacting said copper electroless plating solution with copper halide salt is performed after said step of forming a copper electroless plating solution; and

said array of PZT elements have dimensions of about 250-350 μm in height, 35-45 μm in width and the spacing between said elements is about 10 μm.

19 . The method of claim 18 , wherein said array of PZT elements is an array of rectangular PZT sensing elements.

20 . (canceled)

21 . A method of electroless plating piezoelectric ceramic with copper metal comprising:

contacting said surface of said piezoelectric ceramic with a sensitizing solution to form a piezoelectric ceramic surface sensitized with tin and palladium;

forming a copper electroless plating solution including copper salt;

contacting said copper electroless plating solution with a copper halide salt to form a mixture; and

contacting a surface of said piezoelectric ceramic surface sensitized with tin and palladium with said mixture to form a conductive layer of copper metal on said PZT ceramic surface sensitized with tin and palladium; and wherein:

said step of contacting said copper electroless plating solution with copper halide salt is performed after said step of forming a copper electroless plating solution.

22 . The method of claim 21 , wherein said piezoelectric ceramic is selected from the group consisting of lead zirconate titanate (PZT), lead niobium titanate (PNT), lead scandium niobium titanate (PSNT) and mixtures thereof.