Surface conditioner for electroless deposition

Abstract

To provide a composition capable of conditioning a surface for metal electroless deposition.SOLUTION: A composition includes: a polymer surfactant including a plurality of monomer repeating units including a functional group; metal ions; and water. The functional group in each of the plurality of monomer repeating units forms the metal ions and a complex; in a preferable embodiment, the functional group is amine; the surfactant includes polyethylene imine and / or polyallylamine; the metal ions include cobalt, rhodium, palladium or silver; and also a method for forming the composition and an electroless deposition method using the composition are disclosed.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to compositions for conditioning a surface for electroless deposition of a metal thereon. The present disclosure also relates to methods of forming the compositions and their uses. [Background technology]

[0002] Traditional methods of electroless deposition (eg, electroless plating) of metal onto a surface or substrate involve applying a catalyst onto the surface or substrate prior to depositing the metal onto the surface or substrate.

[0003] In one reported example, a palladium-tin colloid is adsorbed onto a substrate. The palladium-tin colloid is used as a catalyst. The catalyzed substrate is then exposed to concentrated sulfuric acid to form palladium on the substrate. The use of such colloids suffers from the drawback that the colloids tend to aggregate and form precipitates. The aggregated colloidal catalyst results in an uneven coating of palladium on the substrate, and the catalyst precipitate does not even coat the substrate uniformly, resulting in poor yields in the coating process. To address this, methods have been developed that use larger amounts of catalyst or increase the duration of plating runs. However, these methods become uneconomical or require longer processing times.

[0004] Therefore, there is a need to provide a solution that addresses one or more of the above-mentioned shortcomings, which would at least provide improved electroless deposition of metals onto surfaces or substrates. Summary of the Invention

[0005] In a first aspect, there is provided a composition for conditioning a surface for electroless deposition of a metal, said composition comprising: a polymeric surfactant comprising a plurality of repeating units of a monomer, each of the plurality of repeating units comprising a functional group; Metal ions, and water, The functional group in each of the plurality of repeating units forms a complex with the metal ion.

[0006] In another aspect, there is provided a method of forming a composition according to various embodiments of the first aspect, the method comprising: forming a metal salt solution comprising metal ions in water; forming a polymeric surfactant solution comprising a polymeric surfactant, the polymeric surfactant comprising a plurality of repeating units of a monomer, each of the plurality of repeating units comprising a functional group; mixing the metal salt solution with the polymer surfactant solution to form the composition.

[0007] In another aspect, a method of electroless deposition is provided, the method comprising: Treating a surface with a composition as described in various embodiments of the first aspect; contacting the surface with a catalytic metal salt solution to form a catalytically treated surface; contacting the catalytically treated surface with a reducing agent to form a metallized surface; contacting the metallized surface with a plating bath for electroless deposition of metal onto the metallized surface. [Brief explanation of the drawings]

[0008] The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the present disclosure. In the following description, various embodiments of the present disclosure are described with reference to the following drawings: [Figure 1]FIG. 1 shows a schematic diagram of electroless deposition of metal onto a substrate using the surface conditioner of the present disclosure. In step 100, a polymer substrate is immersed in the heated (45°C) surface conditioner with agitation for 3 minutes. The substrate is then rinsed with deionized water 10. Then, in step 102, the substrate is catalyzed by immersing it in a low-concentration PdCl2 ion solution (10 ppm-30 ppm) at room temperature (e.g., 20°C-40°C) with agitation (e.g., stirring) for 5 minutes. Immersion in this catalytic solution primes the substrate surface with Pd catalytic ions. The substrate is then rinsed with deionized water 12. Next, in step 104, the Pd catalyst on the substrate is reduced by immersing it in a reducing agent (e.g., 0.2 M NaPO2H2) at room temperature (e.g., 20°C-40°C) without agitation for 1 minute. The substrate is then rinsed with deionized water 14. Thereafter, in step 106, the substrate is immersed in a plating bath formulated for electroless deposition of the desired metal to be plated onto the substrate. [Figure 2] Figure 2 shows a comparison of a substrate surface treated with a surface conditioner of the present disclosure (see left side of image) and an untreated substrate surface (see right side of image). When treated with the surface conditioner, the polymer substrate is able to successfully undergo electroless deposition. The untreated surface does not undergo electroless deposition even when subjected to the same catalyzed treatment. [Figure 3] Figure 3 shows ultraviolet-visible (UV-vis) spectroscopic analysis of the complexation of nickel ions by polyallylamine. The formation of a new peak at 634 nm and the disappearance of the characteristic peaks of nickel ions at 660 nm and 730 nm indicate the complexation of nickel ions by the amine-based surfactant. [Figure 4] FIG. 4 is a table listing expected results for important electroless metal deposition parameters. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the disclosure may be practiced. Features described in the context of one embodiment may be applicable to the same or similar features in other embodiments. Features described in the context of one embodiment may be applicable to other embodiments even if not explicitly described in those other embodiments. Furthermore, additions and / or combinations and / or substitutions to features described in the context of one embodiment may be applicable to the same or similar features in those other embodiments.

[0010] The present disclosure relates to compositions for conditioning a surface for electroless deposition of a metal thereon. The surface may be the surface of a substrate. In other words, the compositions can be used for electroless deposition of a metal onto a substrate. Because the compositions of the present disclosure condition a surface for electroless deposition of a metal thereon, they may be referred to as "surface conditioners" in the present disclosure. The terms "electroless deposition" and "electroless plating" are used interchangeably herein.

[0011] The present disclosure also relates to methods of forming the compositions and uses of the compositions, which may include electroless deposition methods using the compositions. Details of various embodiments of the composition, methods of forming the composition, uses of the composition, and advantages associated with the various embodiments are described below.

[0012] In the present disclosure, a composition for conditioning a surface for electroless deposition of a metal is provided. The composition may include a polymeric surfactant. The polymeric surfactant may include or be formed from a plurality of repeating units of a monomer. Each of the repeating units may have a functional group. In other words, the polymeric surfactant may have a plurality of functional groups resulting from the repeating units.

[0013] The multiple functional groups present on the polymer surfactant can be the same or different.For example, the polymer surfactant can have multiple functional groups and multiple functional groups.When the polymer surfactant contains two or more types of functional groups, the polymer surfactant can be a copolymer.The copolymer can be a random copolymer or a diblock copolymer.In various embodiments, multiple repeating units can be the same functional group or can contain the same functional group.

[0014] In various embodiments, the functional group may include an amine. In various embodiments, the polymeric surfactant may include polyethyleneimine and / or polyallylamine. In various embodiments, the polymeric surfactant may be present in a range of 0.1 wt % to 0.5 wt %, 0.2 wt % to 0.5 wt %, 0.3 wt % to 0.5 wt %, 0.4 wt % to 0.5 wt %, 0.1 wt % to 0.2 wt %, 0.1 wt % to 0.3 wt %, 0.1 wt % to 0.4 wt %, etc. Such a range is advantageous for wetting the substrate without excessive viscosity or excessive reduction in surface tension. If too little polymeric surfactant is used (below such a range), the wetting effect of the polymeric surfactant and the enhanced catalytic activity provided by the composition may not be adequately achieved. If too much is used, excessive foaming and high viscosity of the conditioner may occur.

[0015] The present composition contains metal ions. The functional group of the polymeric surfactant can form a complex with the metal ion (e.g., a cation) through a coordinate bond. For example, if the functional group of the polymeric surfactant contains an amine, the nitrogen in the amine can form a complex with the metal cation. Further advantageously, the metal ions in the present composition can reduce the volume of the PdCl catalyst solution used subsequently for electroless plating (e.g., lower Pd loading during electroless plating). For example, the PdCl catalyst solution used subsequently for electroless plating can have a lower Pd ion concentration for electroless plating. Conventional electroless plating tends to require high PdCl concentrations (i.e., high Pd loadings). The present composition and method can avoid the use of such conventional high concentrations. In various embodiments, the metal ion can include cobalt, rhodium, palladium, or silver. In various embodiments, the functional group, such as an amine, in each of the plurality of repeating units interacts with and forms a complex with the metal ion. For example, the polymeric surfactant can adhere to the surface of a substrate by reducing the surface tension of the substrate. In addition, most polymer substrates that undergo electroless plating may have etched surfaces, which tend to have numerous cavities, high surface roughness, and free functional groups such as -COOH and -OH. Surfactants may then adhere to the surface through (i) one or more types of bonds via the functional groups and (ii) physical adhesion or absorption.

[0016] In various embodiments, the metal ions may be present in a range of 0.01 wt. % to 0.02 wt. %, 0.01 wt. % to 0.015 wt. %, 0.015 wt. % to 0.02 wt. %, etc. The concentration of the metal ions used may be correlated with the concentration of the polymeric surfactant used. In other words, the amount of polymeric surfactant used and the amount of metal ions used may be interdependent. If too few metal ions are used, the effectiveness of the conditioner in enhancing catalytic activity may be compromised. If too many metal ions are used, the excess metal ions may not be complexed by the polymeric surfactant and may result in metal hydroxides in the presence of an alkaline base, which may then foul the composition. In various embodiments, the metal ions may be present in a range of 0.02 wt. % to 0.02 wt. %, although the metal ions are in the form of a metal ion-polymeric surfactant complex.

[0017] As described above, the composition may further include an alkali metal base. The alkali metal base may be optional. The alkali metal base may be used to adjust the pH of the solution. In various embodiments, the alkali metal base may be or include sodium hydroxide or potassium hydroxide. The alkali metal base may be present in a concentration of 0.1M to 0.5M, 0.2M to 0.5M, 0.3M to 0.5M, 0.4M to 0.5M, 0.1M to 0.2M, 0.1M to 0.3M, 0.1M to 0.4M, etc.

[0018] The composition comprises water, which acts as a compatible solvent for the polymeric surfactant and the metal ions dissolved therein. In other words, the composition is an aqueous composition. The present disclosure includes methods of forming the compositions described in various embodiments of the first aspect above. The embodiments and advantages described for the compositions of the first aspect may be equally valid for the methods of forming the compositions described later herein, and vice versa. Various embodiments and advantages have already been described above and illustrated in the examples demonstrated herein, so they will not be repeated for the sake of brevity.

[0019] The method of forming the composition includes forming a metal salt solution containing metal ions in water, forming a polymeric surfactant solution containing a polymeric surfactant, the polymeric surfactant comprising a plurality of repeating units of a monomer, each of the plurality of repeating units comprising a functional group, and mixing the metal salt solution with the polymeric surfactant solution to form a mixture, which mixture may comprise the composition.

[0020] In various embodiments, forming the metal salt solution can include dissolving a metal salt in water. The metal salt solution dissolved in water provides the metal ions of the composition. As a non-limiting example, if the metal to be plated on the surface or substrate is palladium, the metal salt solution and, therefore, the metal ions can be a palladium (II) chloride (PdCl) solution and palladium (Pd) ions, respectively. Other metal salt solutions can be used depending on the metal to be plated.

[0021] In various embodiments, forming the metal salt solution can include dissolving a metal salt in water such that the metal ions are present at a concentration of 0.02% to 0.2% by weight, 0.02% to 0.04% by weight, 0.02% to 0.03% by weight, 0.03% to 0.04% by weight, etc.

[0022] In various embodiments, forming the polymeric surfactant solution can include dissolving a polymeric surfactant in water such that the polymeric surfactant is present at a concentration of 0.2 wt % to 1.0 wt %, 0.3 wt % to 1.0 wt %, 0.4 wt % to 1.0 wt %, 0.5 wt % to 1.0 wt %, 0.6 wt % to 1.0 wt %, 0.7 wt % to 1.0 wt %, 0.8 wt % to 1.0 wt %, 0.9 wt % to 1.0 wt %, etc. Various embodiments of the polymeric surfactant have been described above and will not be repeated for the sake of brevity.

[0023] In the method, combining the metal salt solution and the polymer surfactant solution may include combining equal volumes of the metal salt solution and the polymer surfactant solution. The method may further include dissolving an alkali metal base in the mixture formed when the metal salt solution and the polymer surfactant solution are mixed. Dissolving the alkali metal base in the mixture may be optional. In the method of the present invention, dissolving the alkali metal base in the mixture may include dissolving the alkali metal base to a concentration of 0.1M to 0.5M, 0.2M to 0.5M, 0.3M to 0.5M, 0.4M to 0.5M, 0.1M to 0.2M, 0.1M to 0.3M, or 0.1M to 0.4M, etc.

[0024] The present disclosure further includes electroless deposition methods. The methods include the use of the compositions described in various embodiments of the first aspect above. The embodiments and advantages described for the compositions of the first aspect and the methods for forming the compositions may also be applicable to the electroless deposition methods described later in this specification, and vice versa. Various embodiments and advantages have already been described above and are illustrated in the examples demonstrated herein, so they will not be repeated for the sake of brevity.

[0025] The electroless deposition method may include treating a surface with the composition described in various embodiments of the first aspect above, contacting the surface with a catalytic metal salt solution to form a catalytically treated surface, contacting the catalytically treated surface with a reducing agent to form a metal-coated surface, and contacting the metal-coated surface with a plating bath for electroless deposition of a metal onto the metal-coated surface.

[0026] In the electroless deposition method, treating the surface with the composition includes heating the composition and stirring the composition in the presence of the surface. As a non-limiting example, the surface or substrate can be immersed in the composition, which has already been heated. Advantageously, this helps to increase the rate of electroless deposition (i.e., improve the reaction rate of the coating reaction of the metal plated thereon) and improve the uniformity of the metal plated thereon. In various embodiments, heating the composition can include heating the composition to a temperature within a range of 40°C to 60°C, 45°C to 60°C, 50°C to 60°C, 55°C to 60°C, 40°C to 55°C, 40°C to 50°C, 40°C to 45°C, etc. Lower temperatures may require a longer surface conditioning step or the use of larger amounts of surface conditioner, potentially damaging the substrate or undesirably altering its surface properties. Higher temperatures may result in excessive evaporation of water from the solution or alteration of the metal complex concentration. In one specific non-limiting embodiment, the surface or substrate can be immersed in the composition that has been preheated to 45°C.

[0027] In various embodiments, the reducing agent can be or can include NaPO2H2. Other reducing agents suitable for reducing the metal catalyst to metal on the surface can be used.

[0028] In various embodiments, the catalytic metal salt solution can contain catalytic metal salts present at concentrations of 10 ppm to 30 ppm, 20 ppm to 30 ppm, 10 ppm to 20 ppm, etc. Higher concentrations can result in high catalyst loss during subsequent cleaning procedures because high concentrations of Pd are washed away. This incurs additional costs for recovering Pd from wastewater. If the concentration is too low, it may be difficult to achieve catalytic effectiveness. The catalytic metal salt can provide metal ions that are different from or the same as those in the present composition. In other words, the catalytic metal salt used in electroless plating is independent of the metal salt used in the present surface conditioner. The metal salt for preparing the surface conditioner can contain metal ions that are different from or the same as those in the electroless plating bath.

[0029] In various embodiments, the electroless deposition method can further include rinsing the surface with water (e.g., deionized water) before contacting the surface with the catalytic metal salt solution. In various embodiments, the electroless deposition method can further include rinsing the catalyst-treated surface with water (e.g., deionized water) before contacting the catalyst-treated surface with a reducing agent. In various embodiments, the electroless deposition method can further include rinsing the metal-coated surface with water (e.g., deionized water) before contacting the metal-coated surface with a plating bath.

[0030] The term "substantially" does not exclude "completely", for example, a composition that is "substantially free" of Y may be completely free of Y. Where necessary, the term "substantially" may be omitted from the definitions of the present disclosure.

[0031] In the context of various embodiments, the articles "a," "an," and "the" used in reference to a feature or feature include a reference to one or more of the feature or feature. In the context of various embodiments, the term "about" or "approximately" applied to a numerical value encompasses the exact value and a reasonable variance, which may be ±20%, ±10%, ±5%, ±1%, ±0.5%, ±0.1%, etc.

[0032] As used herein, the term "and / or" includes any one or more of the associated listed items and all combinations of such listed items. Unless otherwise specified, the terms "comprising" and "comprise," and their grammatical variations, are intended to represent "open" or "inclusive" language, such that the terms include the enumerated requirements but also encompass additional requirements that are not enumerated. Example The present disclosure relates to surface conditioners for pretreating a surface or substrate to promote electroless metal deposition thereon, such as electroless nickel deposition and electroless copper deposition, while reducing the catalyst loading traditionally required to achieve deposition / plating. The surface or substrate may be non-metallic, non-conductive, and / or polymeric.

[0033] The surface conditioner may include a polymeric surfactant composed of multiple repeating units of functional groups (e.g., amine groups) capable of complexing with metal ions. For example, the polymeric surfactant may be dissolved in deionized water along with a metal salt containing the target metal (i.e., the desired metal) to be plated on the surface or substrate. The substrate may be immersed in a solution (i.e., the surface conditioner) containing the polymeric surfactant, the metal salt, and water. The substrate may then be immersed in a catalyst metal salt solution (e.g., a low palladium (Pd) catalyst ion solution such as a PdCl2 solution) with a sufficiently low catalyst concentration. The polymeric surfactant captures the metal salt and (in this case, for example) Pd ions, spreading and adhering to the substrate. The substrate is then immersed in a reducing agent solution (e.g., 0.2 M NaPO2H2) to coat the substrate with the reduced metal (e.g., Pd). The Pd acts as a catalyst to induce electroless plating.

[0034] The present surface conditioners, methods of forming the surface conditioners, and electroless deposition methods using the surface conditioners are described in further detail as non-limiting examples, as set forth below.

[0035] Example 1 Materials The components that make up the present surface conditioner include, but are not limited to, a polymeric surfactant, a metal salt that provides the metal ion, (optionally) a strong alkali metal base, and deionized water.

[0036] The polymeric surfactant may include multiple repeating units of one or more functional groups, each of which may be capable of complexing with a metal ion, non-limiting examples of which include amine groups.

[0037] The metal salt may contain metal ions, which can be formed into a metal that is plated onto a surface or substrate. Example 2 Preparation of Surface Conditioner The preparation of this surface conditioner is described below.

[0038] A metal salt containing the target metal (i.e., the metal to be plated onto a surface or substrate) is first dissolved in deionized water to form a metal salt solution, which may have a metal ion concentration by weight (wt%) ranging from 0.02% to 0.04%.

[0039] A long-chain surfactant having one or more repeating functional groups (e.g., multiple repeating units each having an amine group), such as polyethyleneimine or polyallylamine, is selected and dissolved in deionized water to form a surfactant solution having a concentration ranging from 0.2% to 1.0% by weight.

[0040] The surfactant solution is slowly added to the metal salt solution in equal volumes to form a mixture until the desired volume of conditioner is achieved. Ultraviolet-visible (UV-vis) spectroscopy can be performed to characterize and confirm that all metal ions have been completely complexed by the surfactant and that there is no trace of uncomplexed metal ions.

[0041] A strong alkali metal base (eg, KOH) can be dissolved in the mixture so as to be present at a concentration ranging from 0.1 M to 0.5 M to form a surface conditioner. The final composition of the conditioner can be, for example, 0.1% to 0.5% by weight of surfactant, 0.01% to 0.02% by weight of metal ion, and 0.1M to 0.5M of alkali metal base.

[0042] Example 3 Electroless Deposition Using the Present Surface Conditioner A polymer surface or substrate (eg, an acrylonitrile butadiene styrene (ABS) plate) is treated by immersion in a heated (eg, 45° C.) surface conditioner under agitation, for example, for 3 minutes.

[0043] The treated substrate is then cleaned by rinsing in deionized water for 5-10 seconds. The treated substrate is then catalyzed by immersion in a low-concentration PdCl2 ion solution (10 ppm-30 ppm) at room temperature (e.g., 20°C-40°C) and agitation (e.g., stirring) for 5 minutes. This low-concentration PdCl2 ion solution is a non-limiting example of a catalytic metal salt solution. The catalytic metal salt solution differs from the metal salt solution used to prepare the surface conditioner. The metal salt solution for the surface conditioner has metal ions complexed with a polymeric surfactant. However, because the catalytic metal salt solution does not contain a polymeric surfactant and does not contain additives, metal ions from the catalytic metal salt solution may be present as free metal ions in the catalytic metal salt solution. The use of PdCl2 is not meant to be limiting but is merely an example to demonstrate the present surface conditioner and its use in electroless deposition of metals onto surfaces or substrates. Other ionic catalyst solutions for electroless plating containing metal ions such as silver (Ag), rhodium (Rh), cobalt (Co), etc. ions also worked.

[0044] The treated substrate is then cleaned by rinsing in deionized water for 5-10 seconds. The treated substrate is then immersed in a reducing agent (e.g., 0.2 M NaPO2H2 or any other reducing agent suitable for electroless plating of metals) at room temperature (e.g., 20 °C to 40 °C) without stirring for 1 minute to form a catalyzed substrate with Pd metal.

[0045] The catalyzed substrate with Pd metal is then cleaned by rinsing in deionized water for 5-10 seconds. Finally, the catalyzed substrate with Pd metal is immersed in a plating bath formulated for electroless deposition of the desired metal. A non-limiting example of a plating bath solution can be a nickel electroless plating bath containing 0.2 M sodium citrate, 0.5 M boric acid, 15 g / L nickel(II) sulfate hexahydrate, and 37.5 g / L sodium hypophosphite monohydrate. Commercially available nickel plating baths can be used, such as Uyemura "Mekongka NEN" plating solution or Okuno "Chemical Nickel EXC" plating solution.

[0046] Although the present disclosure has been particularly shown and described with reference to certain embodiments, it will be understood by those skilled in the art that various changes in form and details can be made in the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims. The scope of the present disclosure is therefore indicated by the appended claims, and all changes that come within the range of equivalents of the claims are therefore intended to be embraced.

Claims

1. 1. A composition for conditioning a surface for electroless deposition of a metal, comprising: a polymeric surfactant comprising a plurality of repeating units of a monomer, each of the plurality of repeating units comprising a functional group; Metal ions, Water and Including, the functional group in each of the plurality of repeating units forms a complex with the metal ion; The composition.

2. The composition of claim 1 , wherein the plurality of repeating units comprises the same functional group.

3. The composition of claim 1 or claim 2, wherein the functional group comprises an amine.

4. The composition of any one of claims 1 to 3, wherein the polymeric surfactant comprises polyethyleneimine and / or polyallylamine.

5. A composition according to any preceding claim, wherein the polymeric surfactant is present in the range of 0.1% to 0.5% by weight.

6. The composition of any one of claims 1 to 5, wherein the metal ions comprise cobalt, rhodium, palladium, or silver.

7. The composition of any one of claims 1 to 6, wherein the metal ions are present in the range of 0.01% to 0.02% by weight.

8. The composition of any one of claims 1 to 7, further comprising an alkali metal base.

9. 9. The composition of claim 8, wherein the alkali metal base is present at a concentration of 0.1M to 0.5M.

10. A method of forming the composition of any one of claims 1 to 9, comprising: forming a metal salt solution comprising metal ions in water; forming a polymeric surfactant solution comprising a polymeric surfactant, the polymeric surfactant comprising a plurality of repeating units of a monomer, each of the plurality of repeating units comprising a functional group; mixing the metal salt solution and the polymer surfactant solution to form the composition; The method comprising:

11. The method of claim 10 , wherein forming the metal salt solution comprises dissolving a metal salt in water.

12. 12. The method of claim 11, wherein forming the metal salt solution comprises dissolving the metal salt in water such that the metal ions are present at a concentration of 0.02% to 0.2% by weight.

13. The method of any one of claims 10 to 12, wherein forming the polymeric surfactant solution comprises dissolving the polymeric surfactant in water.

14. 14. The method of claim 13, wherein forming the polymeric surfactant solution comprises dissolving the polymeric surfactant in water such that the polymeric surfactant is present at a concentration of 0.2% to 1.0% by weight.

15. 15. The method of any one of claims 10 to 14, wherein combining the metal salt solution and the polymer surfactant solution comprises combining equal volumes of the metal salt solution and the polymer surfactant solution.

16. 16. The method of any one of claims 10 to 15, further comprising dissolving an alkali metal base in a mixture formed upon mixing the metal salt solution and the polymeric surfactant solution, wherein dissolving the alkali metal base in the mixture comprises dissolving the alkali metal base to a concentration of 0.1 M to 0.5 M.

17. 1. A method for electroless deposition comprising: Treating a surface with a composition according to any one of claims 1 to 9; contacting the surface with a catalytic metal salt solution to form a catalytically treated surface; contacting the catalytically treated surface with a reducing agent to form a metallized surface; contacting the metal-coated surface with a plating bath for electroless deposition of metal onto the metal-coated surface; The method comprising:

18. 18. The method of claim 17, wherein treating the surface with the composition comprises: heating the composition; agitating the composition in the presence of the surface; The method comprising:

19. 19. The method of claim 18, wherein heating the composition comprises heating the composition to a temperature in the range of 40°C to 60°C.

20. The reducing agent is NaPO ２ H ２ The method according to any one of claims 17 to 19, comprising:

21. 21. The method of any one of claims 17 to 20, wherein the catalytic metal salt solution comprises catalytic metal salt present in a concentration of from 10 ppm to 30 ppm.

22. washing the surface with water before contacting the surface with the catalytic metal salt solution; washing the catalytically treated surface with water prior to contacting the catalytically treated surface with the reducing agent; rinsing the metallized surface with water prior to contacting the metallized surface with the plating bath; The method of any one of claims 17 to 21, further comprising:

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