Activator solutions, their preparation and use in electroless plating of surfaces

Claim 2

A PROCESS FOR THE ELECTROLESS METAL PLATING OF A SURFACE WHICH COMPRISES CONTACTING AN OBJECT NON-CATALYTIC SURFACE INTENDED TO BE ELECTROLESSLY METAL PLATED WITH A SUBSTANTIALLY COLLOIDAL METAL PARTICLE-FREE LIQUID CATALYST SOLUTION CONTAINING A SOLUBLE LEWIS BASE-MODIFIED NOBEL METAL-TIN HALIDE COMPLEX AND A HYDRO-HALIDE ACID UNTIL THE SURFACE IS RENDERED CATALYTIC, THE NOBEL METAL OF THE COMPLEX BEING A NOBEL METAL CATALYTIC TO THE CHEMICAL REDUCTION DEPOSITION OF THE METAL DESIRED TO BE PLATED ON SAID SURFACE, THE LEWIS BASE BEING SELECTED FROM THE GROUP CONSISTING OF 1-4C ALKANOLS, COMPOUNDS OF THE FORMULA

Claim 3

The process of claim 1 wherein the Lewis base is added in the formation of the reaction mixture prior to the addition of the noble metal salt, the reaction temperature of the mixture is in the range of about 90* to abut about 135*F., and the catalyst solution has a pH below about 1.

Claim 4

The process of claim 1 wherein the catalytic surface of the object is contacted with a postactivation solution prior to the electroless metal plating for a contact time sufficient to assure exposure of the catalytic noble metal.

Claim 5

The process of claim 3 wherein the post-activator solution is an aqueous HCl solution.

Claim 6

The process of claim 3 wherein the reaction temperature is in the range of about 100*F. to about 120*F.

Claim 7

The process of claim 1 wherein the Lewis base is a mixture of the 1-4C alkanol and the compound of the formula RCOOM.

Claim 8

The process of claim 1 wherein the Lewis base is a mixture of the compound of the formula RCOOM, and the compound of the formula

Claim 9

The process of claim 1 wherein the Lewis base is a 1-4C alkanol.

Claim 10

The process of claim 8 wherein the 1-4C alkanol is methanol.

Claim 11

The process of claim 3 wherein the Lewis base is a 1-4C alkanol.

Claim 12

The process of claim 10 wherein the 1- 4C alkanol is methanol.

Claim 13

The process of claim 10 wherein the soluble stannous halide is adDed in increments, the first incremental addition of the soluble stannous halide being in excess of the amount thereof stoichiometrically required to reduce all noble metal salt to zero valent noble metal.

Claim 14

The process of claim 10 wherein additional 1-4C alkanol is added in increments, at least one incremental addition of the 1-4C alkanol being made simultaneously with the incremental additional of soluble stannous halide.

Claim 15

The process of claim 13 wherein at least one incremental addition of the 1-4C alkanol is made simultaneously with the incremental addition of soluble stannous halide, the 1-4C alkanol and stannous halide being in the same solution which also contains a hydro-halide acid.

Claim 16

The process of claim 6 wherein the compound of the formula RCOOM is a propionate, acetate or formate of an alkali metal.

Claim 17

The process of claim 15 wherein the alkali metal compound is sodium propionate.

Claim 18

The process of claim 2 wherein the nobel metal of the complex is noble and the soluble noble metal salt is a soluble palladium salt.

Claim 19

The process of claim 2 wherein the noble metal of the complex is platinum and the noble metal salt is a soluble platinum salt.

Claim 20

The process of claim 2 wherein the stannous halide is of the formula: SnX2 wherein X is a halogen atom having an atomic number in the range of 17-35 inclusive.

Claim 21

The process of claim 19 wherein the stannous halide is stannous chloride.

Claim 22

The process of claim 3 wherein the electrolessly metal plated surface is electroplated with a desired metal.

Claim 23

The process of claim 2 wherein the Lewis base is methanol, the noble metal salt is palladium chloride, the stannous halide is stannous chloride and the hydro-halide acid is hydrochloric acid.

Claim 24

The process of claim 3 wherein the soluble Lewis base-modified noble metal-tin halide complex is a 1-4C alkanol-modified noble metal-tin halide complex obtained by introducing a hydro-halide acid, water and a 1-4C alkanol into a reaction zone, supplying to the reaction zone a solution of an acid-soluble salt of the noble metal in a hydrohalide acid, mixing the thus-obtained mixture in the reaction zone at a temperature in the range of about 90*F. to about 130*F., adding to the thus-obtained mixture a solution containing a hydro-halide acid and a stannous halide, and holding the resulting mixture for a period of at least about 2 days and sufficient to obtain a catalytically effective solution containing the soluble Lewis base-modified noble metaltin halide complex, the stannous halide being added in excess of the amount required to reduce the noble metal salt to zero valent noble metal, the Lewis base being present in the reaction mixture at the outset of a redox reaction between the stannous halide and novel metal salt to prevent precipitation of zero valent noble metal and formation of a colloidal system, and the Lewis base being added in amount sufficient to obtain the soluble complex, the catalyst solution having a pH less than 1.

Claim 25

The process of claim 23 wherein the hydrohalide acid-and stannous halide-containing solution added to the thus-obtained mixture also contains a 1-4C alkanol.

Claim 26

The process of claim 24 wherein the alkanol is a 1-3C alkanol.

Claim 27

The process of claim 25 wherein the alkanol is methanol.

Claim 28

The process of claim 26 wherein prior to the holding step, the liquid mixture obtained by adding to the thus-obtained mixture the hydro-halide acid-and stannous halide-containing solution also containing the 1-3C alkanol is mixed for about 2-3 hours at a temperature in the range of about 90*F. to about 130*F., followed by separately adding to the resulting mixture a solution of a soluble stannous halide in a hydro-halide acid and another solution of a propionate, acetate foR formate of an alkali metal in a 3-4 hours at a temperature in the range of about 90*F. to about 130*F., and separately adding to the resulting mixture an aqueous solution containing a propionate, acetate for formate of an alkali metal, a hydrohalide acid, and a stannous halide.

Claim 29

The process of claim 27 wherein the 1-3C alkanol is methanol.

Claim 30

The process of claim 27 wherein the alkali metal compound is sodium propionate.

Claim 31

The process of claim 27 wherein the mixing of each mixture is at a temperature in the range of about 100*F. to about 120*F.

Claim 32

The process of claim 30 wherein the hydrohalide acid is hydrochloric acid, the noble metal salt is palladium chloride, the tin halide is stannous chloride, and the alkali metal compound is sodium propionate and the mixture held for a period of at least about 5-6 days and sufficient to obtain the soluble complex.