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

Claim 2

A CATALYST SOLUTION COMPRISING A SUBSTANTIALLY COLLOIDAL METAL PARTICLE-FREE ACIDIC LIQUID SOLUTION CONTAINING A SOLUBLE LOWER ALKANOL-MODIFIED NOBLE METAL-TIN CHLORIDE COMPLEX, AND HYDROCHLORIC ACID, THE SOLUBLE LOWER ALKANOL-MODIFIED NOBLE METAL-TIN CHLORIDE COMPLEX BEING OBTAINED BY MIXING TOGETHER A LOWER ALKANOL, A SOLUBLE NOBLE METAL CHLORIDE, STANNOUS CHLORIDE AND HYDROCHLORIC ACID, AND MAINTAINING THE THUSOBTAINED LIQUID MIXTURE AT A REACTION TEMPERATURE OF A LEAST ABOUT 160*F. BUT BELOW THAT TEMPERATURE AT WHICH AN EXCESSIVE AMOUNT OF NOBLE METAL IS PRECIPITATED FOR A PERIOD SUFFICIENT TO OBTAIN A CATALYTICALLY EFFECTIVE SOLUTION CONTAINING THE SOLUBLE LOWER ALKANOL-MODIFIED NOBLE METAL-TIN CHLORIDE COMPLEX, THE STANNOUS CHLORIDE BEING PRESENT IN EXCESS OF THE AMOUNT THEREOF REQUIRED TO REDUCE THE NOBLE METAL CHLORIDE TO ZERO VALENT NOBLE METAL, THE MOLAR RATIO OF STANNOUS CHLORIDE TO NOBLE METAL CHLORIDE (CALCULATED AS PALLADIUM CHLORIDE) BEING INITIALLY AT LEAST ABOUT 9-10:1 RESPECTIVELY, AND THE LOWER ALKANOL BEING PRESENT IN AMOUNT SUFFICIENT TO OBTAIN A SOLUBLE COMPLEX.

Claim 3

The catalyst solution of claim 1 having a pH of less than 1.

Claim 4

The catalyst solution of claim 2 wherein the lower alkanol is methanol.

Claim 5

The catalyst solution of claim 3 wherein the reaction temperature is maintained in the range of about 160*F. to about 185*F.

Claim 6

The catalyst solution of claim 3 wherein the methanol is present in amount sufficient to obtain a soluble complex but insufficient to result in excessive by-product formation with attendant excessive gas pressure build-up in a closed container ultimately containing the catalyst solution.

Claim 7

The catalyst solution of claim 3 wherein the methanol is added in the formation of the reaction mixture prior to the addition of the noble metal chloride.

Claim 8

The catalyst solution of claim 1 wherein the mixture is maintained at the temperature of at at least about 160*F. but below that temperature at which an excessive amount of noble metal is precipitated for a period of at least about 4-9 hours and sufficient to obtain said soluble complex.

Claim 9

The catalyst solution of claim 1 wherein the mixture is maintained at the temperature of in the range of about 160*F. to about 185*F. for a period of at least about 9 hours and sufficient to obtain said soluble complex.

Claim 10

The catalyst solution of claim 4 wherein the methanol is added in the formation of the reaction mixture prior to the addition of the noble metal chloride.

Claim 11

The catalyst solution of claim 2 wherein the noble metal of the complex is palladium and the soluble noble metal chloride is palladium chloride.

Claim 12

The catalyst solution of claim 3 wherein the reaction temperature is maintained in the range of about 170*F. to about 185*F.

Claim 13

The catalyst solution of claim 2 wherein the stannous chloride is added in increments.

Claim 14

The catalyst solution of claim 2 wherein a soluble alkali stannate is mixed together with the lower alkanol, soluble noble metal chloride, stannous chloride and hydrochloric acid.

Claim 15

The catalyst solution of claim 13 wherein the alkali stannate is a soluble alkali metal stannate.

Claim 16

The catalyst solution of claim 14 wherein the alkali metal stannate is sodium stannate.

Claim 17

The catalyst solution of claim 2 wherein the soluble lower alkanol-modified noble metal-tin chloride complex is obtained by introducing water and a soluble alkali metal stannate into a reaction zone, agitating the resulting mixture until the alkali metal stannate is dissolved in the water, adding to the thus-obtained aqueous solution a solution containing stannous chloride and hydrochloric acid, agitating the resulting mixture, adding hydrochloric acid to the thus-obtained mixture, adding a lower alkanol to the thus-obtained mixture, heating the resulting mixture to a reaction temperature in the range of about 170*F. to about 185*C. while agitating said mixture, slowly adding at a controlled rate a solution of an acid-soluble noble metal chloride in hydrochloric acid to the thus-obtained mixture, adding to the resulting mixture increments of a solution of stannous chloride in hydrochloric acid, separately adding to the thus-obtained mixture hydrochloric acid and stannous chloride, maintaining the resulting mixture at a reaction temperature in the range of about 170*F. to about 185*F. for a period of at least about 9 hours and sufficient to obtain the soluble complex, agitating the resulting mixture, and cooling the thus-obtained mixture to room temperature.

Claim 20

The method of claim 17 wherein the catalytically effective solution has a pH less than 1.

Claim 21

The method of claim 18 wherein the mixture is maintained at the temperature of at least about 160*F. but below that temperature at which an excessive amount of noble metal is precipitated for a period of at least about 4-9 hours and sufficient to obtain said soluble complex.

Claim 22

The method of claim 18 wherein the noble metal of the complex is palladium and the soluble metal chloride is palladium chloride.

Claim 23

The method of claim 18 wherein the lower alkanol is methanol.

Claim 24

The method of claim 18 wherein the stannous chloride is added in increments.

Claim 25

The method of claim 18 wherein a soluble alkali stannate is mixed together with the lower alkanol, soluble noble metal chloride, stannous chloride and hydrochloric acid.

Claim 26

The method of claim 23 wherein the alkali stannate is a soluble alkali metal stannate.

Claim 27

The method of claim 24 wherein the alkali metal stannate is sodium stannate.

Claim 30

A catalyst solution comprising a substantially colloidal metal particle-free acidic liquid solution containing a soluble methanol-modified noble metal-tin chloride complex, and hydrochloric acid, the catalyst solution having a pH of less than 1, the soluble methanol-modified noble metal-tin chloride complex being obtained by introducing water and a soluble alkali metal stannate into a reaction zone, agitating the resulting mixture until the alkali metal stannate is dissolved in the water, adding to the thus-obtained aqueous solution a solution containIng stannous chloride and hydrochloric acid, agitating the resulting mixture, adding hydrochloric acid to the thus-obtained mixture, adding methanol to the thus-obtained mixture, heating the resulting mixture to a reaction temperature in the range of about 170*F. to about 185*F. while agitating said mixture, slowly adding at a controlled rate a solution of an acid-soluble noble metal chloride in hydrochloric acid to the thus-obtained mixture, adding to the resulting mixture increments of a solution of stannous chloride in hydrochloric acid, separately adding to the thus-obtained mixture hydrochloric acid and stannous chloride, maintaining the resulting mixture at a reaction temperature in the range of about 170*F. to about 185*F. for a period of at least about 9 hours and sufficient to obtain the soluble complex, agitating the resulting mixture, and cooling the thus-obtained mixture to room temperature, the stannous chloride being present in excess of the amount thereof required to reduce the noble metal chloride to zero valent noble metal, the molar ratio of stannous chloride to noble metal chloride (calculated as palladium chloride) being initially at least about 9-10:1 respectively, and the methanol being present in amount sufficient to obtain a soluble complex.

Claim 31

A catalyst solution comprising a substantially colloidal metal particle-free acidic liquid solution containing a soluble methanol-modified noble metal-tin chloride complex, and hydrochloric acid, the catalyst solution having a pH of less than 1, the soluble methanol-modified noble metal-tin chloride complex being obtained by introducing water and a soluble alkali metal stannate into a reaction zone, agitating the resulting mixture until the alkali metal stannate is dissolved in the water, adding to the thus-obtained aqueous solution a solution containIng stannous chloride and hydrochloric acid, agitating the resulting mixture, adding hydrochloric acid to the thus-obtained mixture, adding methanol to the thus-obtained mixture, heating the resulting mixture to a reaction temperature in the range of about 170*F. to about 185*F. while agitating said mixture, slowly adding at a controlled rate a solution of an acid-soluble noble metal chloride in hydrochloric acid to the thus-obtained mixture, adding to the resulting mixture increments of a solution of stannous chloride in hydrochloric acid, separately adding to the thus-obtained mixture hydrochloric acid and stannous chloride, maintaining the resulting mixture at a reaction temperature in the range of about 170*F. to about 185*F. for a period of at least about 9 hours and sufficient to obtain the soluble complex, agitating the resulting mixture, and cooling the thus-obtained mixture to room temperature, the stannous chloride being present in excess of the amount thereof required to reduce the noble metal chloride to zero valent noble metal, the molar ratio of stannous chloride to noble metal chloride (calculated as palladium chloride) being initially at least about 9-10:1 respectively, and the methanol being present in amount sufficient to obtain a soluble complex.

Claim 32

The catalyst solution of claim 27 wherein the noble metal is palladium, the noble metal chloride is palladium chloride, the alkali metal stannate is sodium stannate, and the cooling of the thus-obtained mixture is by permitting said mixture to cool to room temperature without agitation of the mixture, and thereafter agitating the thus-obtained solution for at least 15 minutes.

Claim 35

The method of claim 29 wherein the methanol is present in amount sufficient to obtain a soluble complex but insufficient to result in excessive by-product formation with attendant excessive gas pressure build-up in a closed container ultimately containing the catalyst solution.

Claim 36

The method of claim 29 wherein the methanol is added in the formation of the reaction mixture prior to the addition of the noble metal chloride.