JP5742701B2 - Electroless plating method - Google Patents

Description

  The present invention relates to a treatment method and an electroless plating treatment material for performing electroless plating on a treated surface of a resin substrate made of a polymer resin, and in particular, electroless plating capable of improving the adhesion strength of an electroless plating film. The present invention relates to a treatment method and an electroless plating treatment material.

  Conventionally, when a metal plating film is formed on a surface of a polymer resin so as to impart conductivity and gloss, an electroless plating treatment is often performed. The electroless plating treatment is a treatment for forming a metal film on the surface of the polymer resin by chemically reducing and depositing metal ions in the solution on the surface of the resin having no conductivity.

  Thus, since the electroless plating process uses a chemical reduction reaction, unlike electroplating that is electrolytically deposited by electric power, even on the surface of a polymer resin generally made of an insulator. A plating film can be formed. Furthermore, it is also possible to perform electroplating after the formation of the metal coating, and not only the strength of the metal coating but also the design properties are significantly improved.

  By the way, since the metal film formed by electroless plating does not have sufficient adhesiveness with the resin, for example, the following method is adopted as a pretreatment. Specifically, before performing the electroless plating treatment, the treated surface of the resin base material made of ABS resin or the like is treated with ozone water, and the treated surface subjected to the ozone water treatment contains an alkaline solution containing at least a surfactant. Is subjected to alkali treatment, and further, a catalyst adsorption treatment is performed by adsorbing a metal catalyst such as palladium on the treated surface after the alkali treatment (see, for example, Patent Document 1 or 2).

  According to this method, the treatment surface is modified by treatment with ozone water, the treatment surface is modified to a surface containing a carboxyl group, and then the carboxyl group is converted to a carbonyl group by an alkali treatment and a surfactant. This improves the wettability of the resin surface. Thereby, since the wettability of the solution containing the metal catalyst is improved on the treated surface subjected to these treatments, the metal catalyst is likely to adhere to the catalyst surface, and electroless plating can be performed without unevenness.

JP 2005-36292 A JP 2003-183841 A

  However, even if the ozone water treatment and alkali treatment described above are performed, the metal catalyst adheres (adsorbs) to the treated surface of the resin base material, but the metal catalyst is adsorbed only on the treated surface. The deposited electroless plating film may not have sufficient adhesion.

  Furthermore, a resin containing nitrogen (amine) such as an ABS resin is easy to adsorb a metal catalyst, but a hydrocarbon resin such as PP is a resin not containing nitrogen (amine), so the metal catalyst is difficult to adsorb. The treated surface of the resin base material may be difficult to be coated with the electroless plating film.

  This invention is made in view of such a point, The place made into the objective is the processing method which performs the electroless plating which can improve the adhesive force of the plating film formed by electroless plating, And it is providing the electroless-plating processing material.

  As a result of intensive studies, the inventors have previously introduced an amine compound into the treated surface of the resin substrate and the inside (surface layer) before the metal catalyst is adsorbed to the resin substrate in the electroless plating process. Thus, the nitrogen element can be contained up to the treated surface of the resin substrate and the inside of the surface layer, and thereby the metal catalyst can be adsorbed not only to the treated surface of the resin substrate but also to the inside of the surface layer. I thought. In particular, an allylamine polymer having a predetermined molecular weight easily enters the inside from the surface of the resin base material. As a result, the electroless plating is performed with the metal catalyst entering the treated surface of the resin base material and the inside of the surface layer. When it did, the electrolysis plating coat | covered on the process surface acquired the new knowledge that adhesive strength improved.

  The present invention is based on the above-mentioned new findings of the inventors, and the electroless plating treatment method according to the present invention includes a step of oxidizing a treated surface of a resin substrate, and a treatment surface subjected to the oxidation treatment. A step of performing an alkali treatment, a step of bringing the treated surface subjected to the alkali treatment into contact with a solution containing an allylamine polymer having a molecular weight of 1600 or less, and allowing the allylamine polymer to penetrate into the surface layer from the treated surface; It includes at least a step of adsorbing the metal catalyst inside a surface layer including a treatment surface impregnated with a polymer, and a step of performing electroless plating on the treatment surface adsorbed with the metal catalyst. .

  According to the present invention, first, a treatment surface of a resin substrate is oxidized to generate polar groups such as carbonyl groups on the treatment surface. Next, by subjecting the treated surface subjected to the oxidation treatment to an alkali treatment, the carbonyl group described above becomes a carboxylate group, thereby improving the wettability of the treated surface of the resin substrate. .

  Next, by bringing a solution containing an allylamine polymer having a molecular weight of 1600 or less into contact with the treated surface whose wettability has been improved by the alkali treatment, allylamine weight is introduced into the surface layer from the treated surface subjected to the alkali treatment. The coalescence can enter (permeate). The allylamine polymer means a polymer having an allylamine structure. The allylamine polymer is, for example, a hydrochloride, an amidosulfate, a partially carbonyl- or urea-reacted polymer, or a diallylamine. Or a copolymer with dimethylallylamine is also included.

  As a result, the metal catalyst is dispersed inside the treatment surface and the surface layer of the treatment surface, and the metal catalyst can be coordinated and adsorbed to the nitrogen element of the allylamine polymer. By performing electroless plating on the metal catalyst in such a state, the metal catalyst that has entered the inside of the surface layer becomes a starting point, and the adhesion of the electroless plating film can be dramatically improved.

  The polymer resin used as the material for the resin base is epoxy resin, ABS resin, AS resin, AAS resin, PS resin, EVA resin, PMMA resin, PBT resin, PET resin, PPS resin, PA resin, POM resin, PC Resin, PP resin, PE resin, Polymer alloy resin containing elastomer and PP, Modified PPO resin, PTFE resin, Thermosetting resin such as ETFE resin, Thermosetting resin such as phenol resin, Cyanate resin for epoxy resin, for example The added resin may be used, and the type and shape are not limited as long as electroless plating can be performed.

  However, more preferably, hydrocarbon resins containing no nitrogen element, such as polyethylene (PE), polypropylene (PP), ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, cycloolefin polymer (COP). Is used.

  Until now, polymer resin such as ABS resin containing nitrogen element has been subjected to electroless plating in the process of adsorbing the metal catalyst because the nitrogen element on the treated surface of the resin substrate is coordinated to the metal catalyst. In this case, the adhesion of the electroless plating film to the treated surface of the resin substrate could be secured to some extent. However, even if the hydrocarbon resin containing no nitrogen element is adsorbed with the metal catalyst by the conventional method, the metal catalyst is sufficiently adsorbed because the nitrogen element does not exist on the treated surface of the resin base material. I could not.

  Therefore, in the present invention, as described above, the allylamine polymer can be infiltrated into the surface layer from the treated surface, so even if such a resin substrate is used, the treated surface and the treated surface Inside the surface layer, the metal catalyst is dispersed, the dispersed metal catalyst is coordinated to the nitrogen element of the allylamine polymer, and the metal catalyst can be adsorbed to the surface layer inside the surface. Needless to say, the adhesion strength of the electroless plating film is further improved when a polymer resin such as ABS resin containing nitrogen element is used as the resin substrate.

  Furthermore, the present invention also discloses an electroless plating material. An electroless plating treatment material according to the present invention is an electroless plating treatment material in which a treatment surface of a resin substrate is coated with an electroless plating film, and the electroless plating treatment material is nitrogen as the resin substrate. The surface of the resin base material coated with the electroless plating film is coated on the treated surface of a resin base material made of a hydrocarbon-based resin not containing an element. In addition, at least nitrogen and a metal catalyst used in the previous step of the electroless plating treatment are contained.

  According to the present invention, the resin base material is an electroless plating treatment material in which the treatment surface of a resin base material made of a hydrocarbon-based resin containing no nitrogen element is coated with the electroless plating film. Since the surface layer of the resin base material coated with the electroless plating film contains at least nitrogen and a metal catalyst used in the previous step of the electroless plating treatment (specifically, positivity bonding to nitrogen atoms) Therefore, the electroless plating film formed using this metal catalyst as a starting point has good adhesion to the treated surface of the resin substrate.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the adhesive force of the plating film formed by electroless plating, even if it is a hydrocarbon resin which does not contain nitrogen, a plating film with high adhesive force can be formed. .

It is a schematic conceptual diagram for demonstrating the electroless-plating processing method which concerns on this embodiment, (a) is typical sectional drawing for demonstrating an oxidation treatment process, (b) demonstrates an alkali treatment process. (C) is a schematic cross-sectional view for explaining the allylamine polymer infiltration treatment step, (d) is a schematic cross-sectional view for explaining the catalyst adsorption treatment step, (d) ) Is a schematic cross-sectional view for explaining a process of performing electroless plating. The figure which showed the result of having analyzed the process surface of the resin base material of the copper plating processing material of an Example, and the element inside the surface layer.

  The following embodiments of the present invention will be described. In the present embodiment, the electroless plating treatment method according to the present embodiment is a plating treatment method for coating an electroless plating film on a treatment surface of a resin substrate, and includes the following steps.

<Molding process>
A molding step of molding a base material (resin base material) from the polymer resin is performed. As resin, polymer resin, epoxy resin, ABS resin, AS resin, AAS resin, PS resin, EVA resin, PMMA resin, PBT resin, PET resin, PPS resin, PA resin, POM resin, PC resin, PP resin , PE resin, polymer alloy resin containing elastomer and PP, thermoplastic resin such as modified PPO resin, PTFE resin, ETFE resin, thermosetting resin such as phenol resin, and resin obtained by adding cyanate resin to epoxy resin, etc. As long as electroless plating can be performed, the type and shape are not limited. The molding method of the resin substrate is not particularly limited, and various molding methods such as compression molding, extrusion molding, blow molding, and injection molding can be adopted.

  However, in the present embodiment, a hydrocarbon system that does not contain a nitrogen element, such as polyethylene (PE), polypropylene (PP), ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, cycloolefin polymer (COP), etc. Resin is used. Here, the “hydrocarbon resin containing no nitrogen element” is a polymer resin composed of a carbon element and a hydrogen element, and in addition to these elements, an oxygen element may further be contained.

  When such a resin is used as a base material, it is generally difficult to form an electroless plating film even when electroless plating is performed on the treated surface of the base material, or the adhesion strength of the electroless plating film is not sufficiently ensured. However, an electroless plating film having high adhesion to the treated surface of the resin substrate can be obtained by performing the following series of steps.

<Oxidation process>
As shown to Fig.1 (a), an oxidation process process is performed with respect to the resin base material 3 after a shaping | molding. Here, as a treatment for oxidizing at least the treatment surface (resin surface) 31 of the resin base material 3, ozone water (water in which ozone is dissolved) or ozone gas is brought into contact with the surface layer 32 including the base material surface to be the treatment surface. Reforming. Specifically, a polar group such as a carbonyl group is generated on the treatment surface 31 by the oxidation treatment.

  Since the carbonyl group is a functional group capable of forming a chemical bond with a metal atom, it strongly binds to an electroless plating film formed by electroless plating, which will be described later, thereby improving the adhesion strength between the electroless plating film and the resin substrate. be able to.

  When the ozone water is brought into contact with the treatment surface 31 of the resin substrate 3, the ozone water may be applied to the treatment surface 31 of the resin substrate 3 by spraying, or the substrate may be immersed in the ozone water. In this embodiment, ozone water is used, but it is a solution in which ozone can be dissolved. Furthermore, unless the resin base material 3 is damaged, the solvent in which ozone is dissolved is not limited to water. .

  Here, the ozone treatment was performed on the resin base material 3 after molding, but the treatment is not limited to this treatment as long as the treatment surface 31 of the resin base material 3 can be oxidized. In addition, you may immerse the process surface 31 of the resin base material 3 in acidic aqueous solution.

<Alkali treatment process>
As shown in FIG.1 (b), the alkali treatment is performed with respect to the process surface 31 of the resin base material 3 after an oxidation process. Examples of the alkaline component of the alkaline solution include sodium hydroxide, potassium hydroxide, lithium hydroxide, and the like. The treated surface 31 of the resin base material is dissolved at a molecular level to remove the embrittled layer, and sodium and the like. Alkali metal can be applied to the treated surface 31.

  By subjecting the treated surface 31 thus oxidized to an alkali treatment, the carbonyl group described above becomes a carboxylate group, thereby improving the wettability of the treated surface 31 of the resin substrate 3. it can. Thereby, the adsorption property of the metal catalyst to the treatment surface can be enhanced in the catalyst adsorption treatment step described later.

  The alkaline solution may further contain at least a surfactant. The surfactant is for enhancing the adsorptivity of the metal catalyst described later. As a solvent of the solution containing the surfactant and the alkali component, it is desirable to use a polar solvent, and water can be typically used. However, depending on the case, an alcohol solvent or a water-alcohol mixed solvent may be used. Good.

  In addition, it is more preferable to perform a neutralization process (pre-dip process) with acids, such as hydrochloric acid, after this alkali treatment process. A pre-dip process is performed, and the alkali component remaining on the treated surface 31 of the resin base material 3 is neutralized with an acidic solution such as hydrochloric acid. In the catalyst adsorption treatment step, which will be described later, the alkali treatment step can enhance the adsorptivity of the metal catalyst to the treatment surface 31, but if the desired amount of the metal catalyst can be adsorbed, the alkali treatment step May be omitted.

<Allylamine polymer infiltration process>
As shown in FIG. 1 (c), the treated surface 31 after the alkali treatment is brought into contact with a solution containing an allylamine polymer having a molecular weight of 1600 or less so that the allylamine polymer 4 is removed from the treated surface 31 of the resin substrate 3. It penetrates into the surface layer 32. According to experiments by the inventors, when the molecular weight of the allylamine polymer exceeds 1600, the allylamine polymer may not be allowed to permeate the treated surface 31 after the alkali treatment. In some cases, it is not possible to ensure the adhesion strength.

  Here, as allylamine, N, N-dimethylallylamine, N-methyl-N-ethylallylamine, N, N-diethylallylamine, N, N-dipropylallylamine, N, N-dibutylallylamine, N-methylallylamine, N -Ethylallylamine, N-propylallylamine, N-butylallylamine, unsubstituted diallylamine (hereinafter sometimes simply referred to as diallylamine), N-methyldiallylamine, N-ethyldiallylamine, N-propyldiallylamine, N- (2 -Hydroxyethyl) diallylamine, N- (2-hydroxypropyl) diallylamine, etc., and polymerizing them by a general polymerization reaction to give an allylamine polymer having a molecular weight (average molecular weight) of 1600 or less. In That. Furthermore, these hydrochlorides, amide sulfates, or partially carbonyl- or urea-reacted polymers can be obtained. In addition, it is preferable that the molecular weight (average molecular weight) of an allylamine polymer is 1000 or more. When the molecular weight is less than this, the adsorptivity of the allylamine polymer (additive) to the substrate becomes low, and the allylamine polymer is hardly adsorbed on the substrate.

<Catalyst adsorption process>
As shown in FIG. 1D, a catalyst adsorption treatment step is performed on the treated surface 31 that has been subjected to alkali treatment. For example, when using a palladium catalyst as the metal catalyst to be adsorbed, the treated surface treated with alkali is immersed in a catalyst solution (catalyzer) in which palladium chloride and tin chloride are dissolved in an aqueous hydrochloric acid solution. As a result, the metal catalyst is adsorbed inside the treatment surface 31 and the surface layer 33 of the treatment surface 31. Furthermore, the treatment surface is brought into contact with an acidic solution to activate the palladium catalyst.

  As the metal catalyst, a palladium catalyst is used from the viewpoint of versatility and precipitation, but metal catalysts such as gold, silver, cobalt, nickel, ruthenium, cerium, iron, manganese, and rhodium may be used.

<Electroless plating treatment>
As shown in FIG.1 (e), the electroless-plating process is performed with respect to the process surface 31 in which the metal catalyst was adsorbed. Specifically, the treatment surface 31 of the resin base material 3 is immersed in an electroless plating solution, and a metal contained in the electroless plating solution is deposited on the treatment surface 31 by electroless plating, so that an electroless plating film is formed. 35 is coated. The electroless plating is performed by, for example, electroless nickel plating or electroless copper plating by a generally known method, and the electroless plating solution is more stable in an aqueous solution in which a source metal is dissolved. An agent, a complexing agent, a reducing agent, and the like may be included.

  Next, the surface layer (specifically, from the treated surface subjected to the alkali treatment by contacting a solution containing an allylamine polymer having a molecular weight of 1600 or less with the treated surface whose wettability has been improved by the alkali treatment. The allylamine polymer can be introduced into the inside of the surface at least 70 nm thick from the surface).

  Thereby, since the allylamine polymer can be made to enter the inside of the surface layer 33 from the treated surface 31, even if the hydrocarbon-based resin base material 3 containing no nitrogen is used, the treated surface 31 and The metal catalyst is dispersed inside the surface layer of the treatment surface 31, the dispersed metal catalyst is coordinated to the nitrogen element of the allylamine polymer, and the metal catalyst can be adsorbed to the inside of the surface layer 33 of the treatment surface 31. .

  As a result, the metal catalyst is dispersed inside the treatment surface 31 and the surface layer 33 of the treatment surface 31, and the metal catalyst can be coordinated and adsorbed to the nitrogen element of the allylamine polymer. By performing electroless plating on the metal catalyst in such a state, the surface layer 33 of the resin base material 3 coated with the electroless plating film 35 (specifically, a thickness of at least 70 nm from the surface). The electroless plating treatment material 1 containing at least nitrogen and the metal catalyst used in the previous step of the electroless plating treatment can be obtained. In such an electroless plating treatment material 1, the metal catalyst that has entered the surface layer 33 of the resin base material 3 is the starting point, and the adhesion of the electroless plating film 35 can be dramatically improved.

The present invention will be described based on the following examples.
As the resin substrate, a cycloolefin polymer (COP) resin (hydrocarbon resin) resin substrate was prepared. And the electroless nickel plating process was performed. Specifically, first, ozone water is brought into contact with the treated surface of the resin base material at a treatment temperature of 20 ° C. (normal temperature) at a treatment temperature of 20 ° C. (room temperature) and an immersion time of 16 minutes. Water treatment (oxidation treatment) was performed.

  Sodium hydroxide (aqueous solution 50 g / L) was brought into contact with the treated surface subjected to the oxidation treatment at 50 ° C. for 5 minutes, the treated surface was subjected to alkali treatment, and then the treated surface was washed with water. Next, an aqueous solution (5 ml / L) containing a polyallylamine polymer having an average molecular weight of 1600 is brought into contact with a treated surface that has been subjected to an alkali treatment at 50 ° C. for 5 minutes. Allylamine polymer was infiltrated. Furthermore, the pre-dip process was performed and the alkali component which remained on the process surface 31 of the resin base material 3 by the alkali treatment was neutralized with the acidic solution (PC-64H made by Ebara Eugelite). In addition, the average molecular weight of a polyallylamine polymer is a thing of the manufacturer description of (Nittobo Medical Co., Ltd. PAA series). In general, the average molecular weight is measured by gel permeation chromatography.

Next, in a catalyst adsorption step, a solution (catalyzer (PC-65H: manufactured by Sugawara Eugleite)) in which palladium chloride (PdCl ₂ ) and tin chloride (SnCl ₂ ) are dissolved in an aqueous hydrochloric acid solution is treated at 50 ° C., The catalyst adsorption treatment was performed under conditions of an immersion time of 5 minutes. Next, activation treatment is performed on an aqueous sulfuric acid solution (accelerator (PC-66H: manufactured by Sugawara Eugilite)) under the conditions of a treatment temperature of 30 ° C. and an immersion time of 5 minutes, and Pd—Sn is oxidized and reduced to remove Sn. , Pd metal was deposited.

Next, as an electroless plating treatment, a copper sulfate (CuSO ₄ ) aqueous solution, 0.03 M, formaldehyde (HCHO), and 0.35 M electroless copper plating solution are used, and the treatment temperature is 30 ° C. and the immersion time is 15 minutes. Then, electroless copper plating was deposited. Thereby, the electroless copper plating processing material by which the processing surface of the resin base material was coat | covered with the electroless copper plating film was obtained.

Furthermore, the electroless copper plating treatment material was heat treated at 100 ° C. for 60 minutes, and subjected to electrolytic copper plating in a copper sulfate aqueous solution to a thickness of 2.7 A / dm ³ , 45 minutes, 25 μm, A heat treatment was performed at 100 ° C. for 60 minutes to obtain a copper plating material.

(Comparative Example 1)
A copper plating material was produced in the same manner as in the example. The difference from the examples is that copper-plated materials were prepared using polyallylamine polymers having an average molecular weight of 5000, 8000 and 15000, respectively. In addition, these average molecular weights are molecular weights described by manufacturers.

(Comparative Example 2)
A copper plating material was produced in the same manner as in the example. The difference from the examples is that the step of bringing the polyallylamine polymer into contact with the treated surface of the resin substrate and permeating it was not performed. However, in the case of Comparative Example 2, the electroless copper plating film was not coated on the treated surface even when electroless plating was performed.

<Adhesion evaluation test of plating film>
The adhesion of the plating film of the copper plating material according to the example and the comparative example was measured. Specifically, a notch on a strip having a width of 10 mm is put into a copper plating film on a resin base material, and a copper plating film (specifically, according to JIS H8630 (adhesion test method)) using the test piece. Measured the adhesion strength (peel strength) of the electroplated film. The results are shown in Table 1.

<Secondary ion mass spectrometer>
The elements in the surface layer along the thickness direction of the resin base material from the interface (treated surface) with the copper plating film of the copper plating treatment material of the example and the comparative example were subjected to D-SIMS using a secondary ion mass spectrometer. analyzed. FIG. 2 is a result of analyzing the treatment surface of the resin base material of the copper plating treatment material of the example and the elements inside the surface layer thereof. The vertical axis in FIG. 2 corresponds to the amount of elements contained in the resin surface layer, and the horizontal axis represents the depth from the treated surface of the resin base material.

〔Results and Discussion〕
As shown in Table 1, the adhesion strength of the copper plating film according to the copper plating treatment material of the example is higher than that of the comparative example 1, and further, as shown in FIG. It was found that nitrogen atoms and palladium elements exist in a dispersed manner on the treated surface of the resin substrate and the surface layer. On the other hand, from the result of the D-SIMS analysis, nitrogen atoms and palladium elements were present in a dispersed manner on the treated surface of the resin base material according to the copper-plated treated material of Comparative Example 1; I found out that I did not.

  From this, it is considered that the allylamine polymer can enter the inside of the surface layer from the treated surface of the resin base material by contacting with a solution containing an allylamine polymer having a molecular weight of 1600 or less as in Examples. It is done. As a result, the palladium catalyst is dispersed inside the treated surface and the surface layer of the treated surface, and the palladium catalyst is coordinated and adsorbed to the nitrogen element of the allylamine polymer. By performing electroless plating on the metal catalyst in such a state, the metal catalyst that entered the surface layer was the starting point, and it was thought that the adhesion of the electroless plating film could be dramatically improved. It is done.

  Further, in the case of Comparative Example 2, since the allylamine polymer was not brought into contact with the treatment surface, there was no nitrogen (amine) on the treatment surface and its surface layer, and the palladium catalyst was coordinated on the treatment surface and inside. Therefore, it can be considered that the electroless copper plating film was not coated on the treated surface.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed.

  3: resin base material, 31: treated surface, 32: surface layer, 33: surface layer, 35: electroless plating film

Claims (2)

And oxidation treatment step of performing oxidation treatment on the treated surface of the resin substrate,
An alkali treatment step of performing an alkali treatment on the oxidized treatment surface;
The treated surface was subjected to the alkali treatment, by contacting a solution containing an A Riruamin polymer, and allylamine polymer infiltration process step of penetrating into the surface layer of the allylamine polymer from the treated surface,
A catalyst adsorption treatment step for adsorbing a metal catalyst inside the surface layer including the treated surface infiltrated with the allylamine polymer;
An electroless plating treatment step of performing electroless plating on the treated surface on which the metal catalyst is adsorbed, and comprising at least an electroless plating treatment method,
In the oxidation treatment step, the treatment surface of the resin base material is oxidized using ozone,
In the allylamine polymer permeation treatment step, the allylamine polymer is permeated into the surface layer from the treatment surface using an allylamine polymer having a molecular weight of 1600 or less. Method.   The electroless plating method according to claim 1, wherein a hydrocarbon-based resin not containing a nitrogen element is used as the resin base material.

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