WO2015045449A1

WO2015045449A1 - Laminate and method for producing same

Info

Publication number: WO2015045449A1
Application number: PCT/JP2014/058768
Authority: WO
Inventors: 宏明安藤; 尚泰井土; 順治吉田; 弘志度会; 健二郎森本
Original assignee: 豊田合成株式会社
Priority date: 2013-09-26
Filing date: 2014-03-27
Publication date: 2015-04-02

Abstract

The problem addressed by the present invention is to provide: a laminate that has increased adhesiveness between an Sn plating layer and a coating film laminated on the Sn plating layer, and that can prevent delamination at the interface surface; and a method for producing the laminate. The method for producing a laminate resulting from electrically forming a deposit layer on an Sn plating layer laminated to the surface of a substrate is provided with: an Sn plating step for laminating a glossy Sn plating layer comprising Sn or an Sn alloy onto a substrate in a plating solution containing Sn and a brightener; an acid dipping processing step after the Sn plating step for immersing the glossy Sn plating layer on the substrate in a sulfuric acid solution having a concentration of at least 10 mass% or a hydrochloric acid solution having a concentration of at least 3.5 mass% at 50-80°C for 1-30 minutes; and a deposit layer forming step after the acid dipping processing step for electrically forming a deposit layer on the Sn plating layer.

Description

Laminated body and method for producing the same

The present invention relates to a laminate having a Sn plating layer on the surface of a substrate and a method for producing the same.

Conventionally, a laminate subjected to metal plating is used as a surface treatment for various vehicle parts and the like. As this type of laminate, one obtained by applying a metal plating treatment to an acrylonitrile / butadiene / styrene copolymer (ABS) resin to give a metal-like appearance is known. The metal plating process of ABS resin is generally performed by performing electroless Ni plating in the presence of Sn catalyst to impart conductivity to the ABS resin substrate, then Cu plating, semi-bright Ni (SBN) plating, and gloss Ni (BN) plating processing, Joule Ni (DN) plating processing, and Cr plating processing are sequentially performed by an electroplating method. The Cu plating layer is laminated mainly to give ductility that can follow the extension of the ABS resin base material, and a base material made of a synthetic resin that gives rigidity to the laminate and the metal that constitutes each plating layer It relieves thermal stress based on the difference in linear expansion coefficient and prevents the occurrence of cracks on the surface of the laminate and the deterioration of the adhesion of each plating layer. Each Ni plating layer has a function of preventing corrosion of the outermost Cr plating layer and imparting corrosion resistance to the laminate from the viewpoint of sacrificial corrosion protection. Further, the Cr plating layer has a function of imparting a bright appearance to the laminate and imparting chipping resistance (scratch resistance). Each layer of these conventional laminates has a different function, and imparts necessary functions to be required for members to which the laminate is applied.

However, such a laminate has a multilayer structure in which a large number of metal plating layers are laminated, so that the machining process becomes complicated and takes a long time, and the material cost increases and the cost increases. was there.

Therefore, by integrating the functions of these layers, it has been studied to reduce the number of layers, simplify the process, and reduce material costs. The present inventors have focused on Sn as a metal having an appropriate ductility that can follow a base material made of synthetic resin, for example, from the viewpoint of preventing cracks in the laminate and suppressing cracks.

Patent Document 1 describes an invention relating to a method for producing a resin-coated tin-plated steel sheet in which a small amount of a Ni plating layer is formed on a steel sheet and then a resin film is coated thereon. ing. Patent Document 2 describes an invention relating to a method for producing a Sn-plated steel sheet, in which a Sn-plating treatment is performed on a steel sheet, a silane coupling agent is applied, and a resin film is coated thereon. Yes.

Japanese Patent Laid-Open No. 5-98465 JP 2003-231989

However, the surface treatment described in each of these patent documents is based on a matte Sn plating treatment in which a brightener is not contained in the Sn plating bath, and satisfactory brightness cannot be imparted by the Sn plating layer. There was a problem. In addition, there is a problem that the adhesion between the Sn plating layer and the film laminated on the Sn plating layer is not sufficient, and the film easily peels off on the surface of the obtained Sn plated steel sheet. Therefore, when this is applied to, for example, various vehicle parts, satisfactory performance cannot be obtained as performance required for various vehicle parts, and there is room for improvement.

The present invention has been made in order to solve the problems existing in the prior art, and its purpose is to improve the adhesion of the deposited layer laminated on the bright Sn plating layer to the bright Sn plating layer. And providing a laminate and a method for manufacturing the same, which can prevent peeling at the boundary surface.

In order to achieve the above object, the method for producing a laminate of the present invention is a method for producing a laminate in which a deposited layer is electrically formed on a Sn plating layer laminated on the surface of a substrate. In a plating bath containing a brightener and Sn, a Sn plating step of laminating a bright Sn plating layer made of Sn or an Sn alloy on the substrate, and after the Sn plating step, the bright Sn plating layer on the substrate An acid immersion treatment step of immersing in either a sulfuric acid solution having a concentration of 10% by mass or more or a hydrochloric acid solution having a concentration of 3.5% by mass or more at 50 to 80 ° C. for 1 to 30 minutes, and after the acid immersion treatment step, And a deposition layer forming step of electrically forming a deposition layer on the bright Sn plating layer.

According to this configuration, by immersing the bright Sn plating layer with an acid solution having a high concentration, the surface of the bright Sn plating layer is roughened and minute uneven portions are formed. Then, the precipitation layer deposited on the upper surface of the bright Sn plating layer enters the recess formed on the surface of the bright Sn plating layer, and an anchor effect is generated depending on the form of the bright Sn plating layer / deposition layer interface. The physical adhesion between the deposited layer can be improved. In addition, the oxide film is removed from the surface of the bright Sn plating layer by an immersion treatment with a high concentration acid solution. Thereby, the fall of the chemical adhesiveness between the glossy Sn plating layer and precipitation layer by an oxide membrane | film | coat can be suppressed.

By laminating the bright Sn plating layer, suitable ductility and bright appearance can be imparted to the laminate, and the adhesion of the deposited layer laminated on the bright Sn plating layer to the bright Sn plating layer Can be improved, and peeling at the interface can be prevented.

In the method for producing a laminate, the acid dipping treatment step is performed such that the surface of the bright Sn plating layer after the acid dipping treatment has a roughness of 0.040 to 0.080 μm, and the undulation is 0 to 0.040 μm. It is preferable.

According to this configuration, the adhesion of the deposited layer to the bright Sn plating layer can be improved.
The manufacturing method of the laminate includes an acid rinsing treatment step of rinsing the surface of the bright Sn plating layer on the substrate with an acid solution having a lower concentration than the acid solution used in the acid immersion treatment step after the acid immersion treatment step. Is preferred.

According to this configuration, it is possible to prevent acid from being brought into the precipitation layer forming step, and to prevent the adhesion of the precipitation layer to the bright Sn plating layer from decreasing.
In the manufacturing method of the said laminated body, it is preferable that the said acid rinse process process uses the same kind of acid as the acid in the acid solution used at the said acid immersion process process.

According to this configuration, the acid solution on the bright Sn plating layer used in the acid immersion treatment step can be easily replaced.
In the method for manufacturing a laminate, the base material is preferably formed by subjecting a synthetic resin to electroless plating.

According to this configuration, processing and molding are easy, and it is suitable for manufacturing various decorative parts.
In order to achieve the above object, a laminate of the present invention comprises a base material, a bright Sn plating layer laminated on the base material, and a deposited layer laminated on the bright Sn plating layer, The bright Sn plating layer is made of Sn or Sn alloy containing a brightener, and the surface of the bright Sn plating layer has a roughness of 0.040 to 0.080 μm and a undulation of 0 to 0.040 μm. The gist.

According to the method for producing a laminate of the present invention, it is possible to improve the adhesion of the deposited layer laminated on the bright Sn plating layer to the bright Sn plating layer and to prevent peeling at the boundary surface.

It is a SEM photograph of the surface of the bright Sn plating layer, (A) is the surface of the bright Sn plating layer before the acid immersion treatment, and (B) is an acid immersion treatment at 50 ° C. for 5 minutes using an 80 mass% sulfuric acid solution. The surface of the bright Sn plating layer, (C) is the surface of the bright Sn plating layer that has been subjected to an acid immersion treatment at 50 ° C. for 30 minutes using an 80% by mass sulfuric acid solution. It is the photograph of the surface after the chipping test with respect to the laminated body of Example 4, Comprising: (A) is the surface of the laminated body which formed the precipitation layer by acid immersion non-processing, (B) is using 80 mass% sulfuric acid solution. The surface of the laminate on which a deposited layer was formed after an acid immersion treatment at 50 ° C. for 5 minutes, (C) is a laminate in which a deposited layer was formed after an acid immersion treatment at 50 ° C. for 30 minutes using an 80 mass% sulfuric acid solution. Surface.

Hereinafter, an embodiment embodying the present invention will be described.
The manufacturing method of the laminated body of this embodiment, after imparting conductivity to the surface of the synthetic resin substrate by electroless Ni plating or electroless Cu plating, laminating a bright Sn plating layer by electrolytic plating, After the surface of the bright Sn plating layer is subjected to an acid dipping treatment and an acid rinsing treatment, a deposited layer is electrically formed on the bright Sn plating layer.

The base material made of synthetic resin can be appropriately selected in consideration of rigidity, ease of processing, heat resistance, and the like. For example, acrylonitrile / butadiene / styrene copolymer (ABS) resin, polycarbonate (PC) resin, PC / ABS alloy (PC / ABS blend resin), polypropylene (PP) resin, polymethyl methacrylate (PMMA) resin, modified polyphenylene It can be appropriately selected from known synthetic resins such as ether (PPE) resin, polyamide resin, polyacetal resin, or olefinic thermoplastic elastomer (TPO). These various synthetic resins can be used after being molded by a known molding method such as an injection molding method, an extrusion molding method, a blow molding method, or a compression molding method.

As a pretreatment for laminating the bright Sn plating layer on the surface of the substrate, first, an electroless Ni plating treatment or an electroless Cu plating treatment for imparting conductivity to the substrate surface is performed.
The electroless Ni plating treatment can be performed by a conventionally known method. For example, after the ABS resin substrate is immersed in a surfactant-containing bath to degrease the substrate surface, the substrate surface is etched by immersion in a chromic acid / sulfuric acid solution. Subsequently, a catalyst represented by a Pd / Sn mixed colloidal catalyst or the like is applied to the surface of the substrate and activated, and then an electroless Ni plating treatment is performed. Electroless Ni plating treatment includes phosphinate, tetrahydroborate, dimethylamine borane (DMAB), or reducing agents such as hydrazine, nickel agents such as nickel sulfate and nickel chloride, complexing agents, accelerators, stabilizers, It can be performed by immersing in a plating bath containing a pH adjuster, a surfactant and the like.

The electroless Cu plating treatment can also be performed by a conventionally known method. The pretreatment of the ABS resin base material may be performed in the same manner as in the case of the electroless Ni plating treatment. The electroless Cu plating treatment is typically a formaldehyde bath using formaldehyde as a reducing agent, but is not limited thereto. It may be carried out in a bath using borohydride such as potassium tetrahydroborate, DMAB, sodium borohydride, glyoxylate, hypophosphite, phosphinate, cobalt (II) salt, hydrazine, etc. as a reducing agent. it can. For example, when performed in a formaldehyde bath, in addition to formaldehyde as a reducing agent, copper sulfate as a copper salt, Rochelle salt as a complexing agent or ethylenediaminetetraacetic acid (EDTA), a pH adjuster, a stabilizer, an accelerator, It can be performed by immersing in a plating bath containing a film improver, a surfactant and the like.

Next, an Sn plating process for laminating a bright Sn plating layer on the electroless plating layer is performed. First, by electroless plating treatment, the surface of the base material on which the electroless plating layer is formed and provided with conductivity is washed with water to remove dirt, and then electroless plating is performed in a plating bath containing a brightener and Sn. A bright Sn plating layer is laminated on the layer.

The Sn plating process can be performed by a conventionally known electrolytic plating method. The Sn plating bath may be any of an acidic bath, an alkaline bath, and a neutral bath. In the case of an acidic bath, any of a sulfuric acid bath, a borofluoride bath, and an organic sulfonic acid bath can be used. For example, in an organic sulfonic acid bath, methane in which stannous sulfate, cresol sulfonic acid, formalin compounds (formaldehyde), amine-aldehyde brighteners, surfactants, pH adjusters, etc. are dissolved in methane sulfonic acid Electroplating can be performed in a sulfonic acid bath under conditions of a processing temperature of 10 to 20 ° C., a cathode current density of 0.3 to 1.5 A / dm ² , and an anode current density of 1.0 to 3.0 A / dm ^2. .

Note that the Sn plating treatment may be performed using a Sn alloy plating bath. For example, Sn—Pb alloy plating bath, Sn—Co alloy plating bath, Sn—Ni alloy plating bath, Sn—Ni—Cu alloy plating bath, Sn—Cu—Zn alloy plating bath, Sn—Fe alloy plating bath, Sn— Various Sn alloy plating treatments may be performed using an Fe—Zn alloy plating bath or the like. These Sn alloy plating processes can be performed by a conventionally known method.

A brightening agent is contained in the Sn plating bath so that the glossy Sn plating layer to be laminated provides a bright appearance suitable for the laminate. As the brightener, generally known brighteners can be appropriately used. For example, aldehyde compound-based brighteners or unsaturated carboxylic acid compound-based brighteners include 1-naphthaldehyde, 2-naphthaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, 2,4- Dichlorobenzaldehyde, 2,6-dichlorobenzaldehyde, o-methoxybenzaldehyde, p-methoxybenzaldehyde, 3-indolecarboxaldehyde, formaldehyde, acetaldehyde, salicylaldehyde, paraaldehyde, butyraldehyde, isobutyraldehyde, propionaldehyde, n-valeraldehyde, Allylaldehyde, glutaraldehyde, 2-thiophenaldehyde, 3-thiophenaldehyde, o-anisaldehyde, m-anisaldehyde, p- Anisaldehyde, p-nitrobenzaldehyde, p-hydroxybenzaldehyde, succinaldehyde, capronaldehyde, isovaleraldehyde, acrylic acid, methacrylic acid, ethacrylic acid, ethyl acrylate, methyl methacrylate, butyl methacrylate, crotonic acid, pyropyrene- Examples thereof include 1,3-dicarboxylic acid, cinnamic acid, benzoic acid, fumaric acid, phthalic acid, citraconic acid, itaconic acid and the like.

Other brighteners include vanillin, acrolein, glyoxal, aldol, 1-benzylidene-7-heptanal, 2,4-hexadienal, cinnamaldehyde, amine-aldehyde condensate, mesityl oxide, isophorone, diacetyl, hexanedione -3,4, acetylacetone, 3-chlorobenzylideneacetone, sub.pyridylideneacetone, sub.furfuridineacetone, sub.tenylideneacetone, 4- (1-naphthyl) -3-buten-2-one, 4- (2-furyl) -3-buten-2-one, 4- (2-thiophenyl) -3-buten-2-one, curcumin, benzylideneacetylacetone, benzalacetone, acetophenone, (2,4-3,4 -) Dichloroacetophenone, benzylideneacetophenone, 2-cinnamylchi Phen, 2- (ω-benzoyl) vinyl furan, vinyl phenyl ketone, (o-, m-, p-) toluidine, (o-, p-) aminoaniline, aniline, (o-, p-) chloroaniline, (2,5-3,4-) chloromethylaniline, N-monomethylaniline, 4,4'-diaminodiphenylmethane, N-phenyl- (α-, β-) naphthylamine, methylbenztriazole, 1,2,3 -Triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,3-benztriazine, imidazole, 2-vinylpyridine, indole, quinoline, reaction product of monoethanolamine and o-vanillin, etc. Is mentioned.

As the brightener, one type may be selected and used, or a plurality of types may be used in combination. The amount of the brightener added varies depending on the type of brightener to be added, but is preferably 0.01 to 1.0 g / l as the total concentration in the Sn plating bath. When the concentration of the brightening agent is 0.01 g / l or more, the dispersibility and adhesion of Sn to the surface of the base material are improved, and an appropriate bright appearance can be imparted to the surface of the base material.

Next, the base material on which the bright Sn plating layer is laminated is immersed in an acid solution to perform an acid immersion treatment on the surface of the bright Sn plating layer. The acid dipping treatment performed here is performed by dipping in an acid solution at a higher temperature and a higher concentration than the acid surface treatment performed as a pretreatment of the plating treatment in a conventionally known plating treatment.

First, the positioning of the acid dipping process of this embodiment will be described.
Sn laminated by Sn plating is a metal with moderate ductility that can follow a base material made of synthetic resin. In the conventional laminate, for example, when a Ni plating layer is laminated on a Sn plating layer The adhesion at the interface between the two is relatively good. However, in order to make the Sn plating layer multifunctional, if a brightening agent is mixed in the Sn plating bath to give a bright appearance to the Sn plating layer, the surface shape of the bright Sn plating film becomes smooth. Is observed. According to the observation with a scanning electron microscope (SEM) photograph, an uneven shape is observed on the surface of the matte Sn plating layer, and the adhesion at the interface between the matte Sn plating layer and the Ni plating layer is relatively good. In contrast, it was observed that the surface of the bright Sn plating layer was smooth, and peeling occurred at the interface between the bright Sn plating layer and the Ni plating layer.

Further, when the surface composition of the Sn plating layer was measured by energy dispersive X-ray analysis (EDS), the distribution of oxygen was not measured on the surface of the matte Sn plating layer, and no oxide film was formed on the surface. However, on the surface of the bright Sn plating layer, the oxygen ratio measured by EDS was 23.5 atm%, and it was predicted that an oxide film was formed.

As a result, the surface of the bright Sn plating layer has a lower physical adhesion with the Ni plating layer due to its smoothness, and the presence of the oxide film on the surface of the bright Sn plating layer causes a gap between the bright Sn plating layer and the Ni plating layer. It was predicted that the amount of metal bonds in the metal was reduced and the chemical adhesion was lowered. And it was considered that the adhesion of the Ni plating layer to the bright Sn plating layer was lowered by these two factors. These phenomena depend on the concentration of the brightener, and it has been found that the lower the concentration of the brightener, the better the adhesion.

Therefore, the acid immersion treatment here is based on the physical adhesion between the precipitation layer laminated on the bright Sn plating layer and the chemistry with respect to the type and concentration of the brightener contained in the bright Sn plating layer. In order to improve the mechanical adhesion, the surface of the bright Sn plating layer is made in a suitable surface state. Therefore, according to the kind and density | concentration of the brightener to be used, the density | concentration of the acid solution used for an acid immersion process, process temperature, and process time can be determined suitably.

The acid solution to be used is preferably a sulfuric acid solution or a hydrochloric acid solution, and an 80% by mass sulfuric acid solution or a 35% by mass hydrochloric acid solution can be appropriately diluted with water and used. The concentration of the acid solution can be determined as appropriate depending on the type and concentration of the brightener used. From the viewpoint of the adhesion between the bright Sn plating layer and the deposited layer that is electrically deposited on the bright Sn plating layer, sulfuric acid can be used. In the case of a solution, it is preferably used at a concentration of 10% by mass or more, and more preferably 20% by mass or more. In the case of a hydrochloric acid solution, it is preferably used at a concentration of 3.5% by mass or more.

The acid immersion treatment temperature is preferably from room temperature to 80 ° C., more preferably from 50 ° C. to 70 ° C. for both sulfuric acid solution and hydrochloric acid solution. If the acid immersion treatment is performed at a temperature exceeding 80 ° C., the ABS resin base material may be denatured and its rigidity may not be maintained. Moreover, it is not preferable to perform the acid dipping treatment at a temperature lower than room temperature because the reaction with the acid solution is delayed and a sufficient acid dipping effect cannot be obtained, and a long acid dipping treatment time is required.

The acid immersion treatment time for both the sulfuric acid solution and the hydrochloric acid solution is preferably 1 minute or more, more preferably 2 minutes or more, and further preferably 3 minutes or more. If it is less than 1 minute, a sufficient acid immersion effect cannot be obtained, and it becomes difficult to obtain high adhesion at the interface between the bright Sn plating layer and the deposited layer. The acid immersion treatment time can be varied depending on the concentration of the acid solution used in the acid immersion treatment. The higher the concentration of the acid solution, the better the acid immersion effect can be obtained even with a shorter acid immersion treatment time.

Next, an acid rinsing treatment is performed on the surface of the bright Sn plating layer on the substrate that has been subjected to an acid immersion treatment in an acid solution. The acid rinsing process performed here is a process for preventing the acid solution covering the surface of the bright Sn plating layer by performing the acid dipping process from being brought into the next deposited layer forming step.

The acid rinsing treatment is preferably performed using an acid solution of the same type as the acid solution used in the acid dipping treatment and having a lower concentration than that used in the acid dipping treatment step. Also in the acid rinsing treatment, the concentration of the acid solution used for the acid rinsing treatment can be appropriately determined according to the type and concentration of the brightener used, as in the acid dip treatment. For example, when a sulfuric acid solution having a concentration of 10% by mass or more and 80% by mass or less is used in the acid dipping process, the sulfuric acid used in the acid dipping process has a concentration of 8% by mass or more in the acid dipping process. It is preferable to use a sulfuric acid solution having a concentration lower than that of the solution. Further, the acid rinsing treatment temperature in the acid rinsing treatment may be any temperature, and the acid rinsing treatment time may be any time. The acid rinsing treatment temperature and the acid rinsing treatment time may be appropriately determined using as a guide the state in which the concentration of the acid solution covering the substrate surface is equal to the concentration of the acid solution used for the acid rinsing treatment.

Next, a deposited layer forming step of electrically forming a deposited layer on the bright Sn plating layer that has been subjected to the acid rinse treatment is performed. The deposited layer to be formed may be a metal plating layer obtained by a normal electroplating method, or may be a coating film obtained by an electrodeposition coating method.

The metal constituting the deposited layer by the metal plating method may be appropriately selected in consideration of various functions required for the laminate. Thereby, various functions, such as corrosion resistance, glossiness, smoothness, chipping resistance, abrasion resistance, slipperiness, weather resistance, chemical resistance, antibacterial properties, and heat reflectivity, can be imparted to the laminate. Moreover, the electroplating method can be performed by a conventionally well-known method according to each metal plating method.

Also when a coating film is laminated by an electrodeposition coating method, it can be performed by a conventionally known method. You may carry out by any method of cationic electrodeposition coating and anion electrodeposition coating.
When cationic electrodeposition coating is performed using a cationic electrodeposition coating composition as the electrodeposition coating composition, a voltage of 1 to 400 V is usually applied between the substrate and the anode. During electrodeposition coating, the bath temperature of the coating composition is adjusted to 10 to 45 ° C., preferably 15 to 30 ° C. The electrodeposition process includes a step of immersing the base material provided with the bright Sn plating layer in the cationic electrodeposition coating composition, and applying a voltage between the base material as the cathode and the anode, and on the bright Sn plating layer. Although it is comprised from the process of depositing a coating film, the application time of a voltage, an applied voltage, etc. can be performed in accordance with a conventionally well-known method. After electrodeposition coating, the coating formed on the surface of the bright Sn plating layer on the substrate is cured by crosslinking. Curing may be performed by heating the film or by irradiating the film with UV.

When anion electrodeposition coating is performed using an anion electrodeposition coating composition as the electrodeposition coating composition, it can be performed by applying a voltage between the base material and the cathode. The applied voltage, applied time, applied voltage, and the like can be performed by a conventionally known method in the same manner as in the cationic electrodeposition coating.

Next, the effect | action by the manufacturing method of the laminated body of this embodiment is described.
In the present embodiment, the surface of the bright Sn plating layer is subjected to an acid dipping treatment and an acid rinsing treatment so that the acid solution improves physical adhesion and chemical adhesion between the bright Sn plating layer and the deposited layer. Works.

First, in the acid immersion treatment on the surface of the bright Sn plating layer, a high-temperature, high-concentration acid solution acts to roughen the surface of the bright Sn plating layer. As a result, irregularities are formed on the surface of the bright Sn plating layer, the surface roughness is improved, and the physical adhesion is improved by the anchor effect with the deposited layer that has entered the recess.

Also, a high-temperature, high-concentration acid solution acts to remove the oxide film formed on the surface of the bright Sn plating layer. The oxide film that was difficult to remove by the pickling treatment after the normal metal plating treatment can also be removed. Thereby, the chemical adhesiveness in the interface of a gloss Sn plating layer and a precipitation layer improves.

The acid dipping treatment on the surface of the bright Sn layer acts to improve both physical adhesion and chemical adhesion at the interface between the bright Sn plating layer and the precipitation layer, and the adhesion of the precipitation layer to the bright Sn plating layer. To improve.

Such an effect can be obtained by performing an acid dipping treatment in an acid solution having a higher concentration than that used in a normal pickling treatment performed at the time of metal plating, and at a higher temperature than a normal pickling treatment. Is. It is possible to realize roughening of the surface necessary to ensure the adhesion between the bright Sn plating layer and the electrodeposited layer laminated thereon, and the removal of the oxide film that is difficult to remove by normal pickling treatment. To do.

In the acid rinsing treatment subsequent to the acid immersion treatment, an acid solution having a lower concentration than the acid solution used during the acid immersion treatment acts to remove the acid solution during the acid immersion treatment remaining on the surface of the bright Sn plating layer. In the present embodiment, by performing the acid rinsing process with an acid solution having a lower concentration than the acid solution in the acid dipping process, the acid concentration on the surface of the bright Sn plating layer is balanced with the acid concentration of the acid solution used in the acid rinsing process. Thus, the acid concentration that does not affect the formation of the electrically deposited layer can be obtained.

The effect by the manufacturing method of the laminated body of this embodiment is described.
(1) By improving the physical adhesion and chemical adhesion at the interface between the bright Sn plating layer and the precipitation layer, the adhesion of the precipitation layer to the bright Sn plating layer is improved. Thereby, exfoliation of the deposited layer with respect to the gloss Sn plating layer can be suppressed while realizing the ductility capable of following the synthetic resin base material and the bright appearance required for the laminate by the gloss Sn plating layer. It is possible to integrate the functions required of the laminate by the lamination of the bright Sn plating layer and the subsequent acid dipping treatment step and acid rinsing treatment step.

(2) Improve the adhesion of the deposited layer to the surface of the bright Sn plating layer containing the brightener by setting the acid solution in the acid dipping treatment to a higher temperature and higher concentration than the acid surface treatment in the normal plating treatment. Can do. By appropriately determining the temperature and concentration of the acid solution according to the type of the brightening agent, it is possible to satisfactorily maintain the surface state of the laminate while providing a suitable glitter appearance to the laminate.

The above embodiment may be modified as follows.
-In this embodiment, although the synthetic resin was used as a base material, it is not limited to this. Stainless steel, copper, copper alloys (brass, beryl copper, tungsten copper, etc.), special alloys such as aluminum and Ti alloys, glass, ceramics, and the like may be used.

-In this embodiment, although the acid rinse process was performed after the acid immersion process, depending on the kind of acid solution used by the acid immersion process, an acid rinse process can also be abbreviate | omitted.
-The acid solution used in the acid dipping treatment and the acid solution used in the acid rinsing treatment need not be performed with the same kind of acid solution. For example, after acid immersion treatment with a hydrochloric acid solution, acid rinse treatment with a sulfuric acid solution may be performed.

The technical idea that can be grasped from the above embodiment will be described below.
(A) The deposited layer forming step is a method for manufacturing a laminate, which is based on an electrodeposition coating method.
(B) The manufacturing method of the laminated body whose said deposit layer formation process is based on the electroplating method.

Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
After the gloss Sn plating layer was laminated on the ABS resin base material provided with conductivity by performing electroless Ni plating treatment, acid immersion treatment and acid rinsing treatment were performed. Thereafter, a bright Ni plating treatment, a microporous Ni plating treatment, and a Cr plating treatment were sequentially performed, and the obtained laminate was evaluated by a tape peeling test. In the acid dipping treatment and the acid rinsing treatment, an appropriate acid concentration, treatment temperature, and treatment time were examined using a sulfuric acid solution. In addition, the surface roughness of the bright Sn plating layer after the sulfuric acid immersion treatment was observed with a scanning electron microscope (SEM), and the oxygen ratio of the surface was subjected to component analysis by energy dispersive X-ray analysis (EDS). The gloss Sn plating layer after the treatment was evaluated.

(Sn plating process)
A bright Sn plating treatment was performed by laminating a bright Sn plating layer on the ABS resin base material provided with conductivity by performing an electroless Ni plating treatment. This bright Sn plating treatment was performed in a methanesulfonic acid bath. The bath composition is stannous sulfate (SnSO ₄ ) 40 g / L, sulfuric acid (H ₂ SO ₄ ) 100 g / L, cresolsulfonic acid 30 g / L, formaldehyde 5 g / L, and amine-aldehyde brightener 40 mL / L. . The bright Sn plating treatment is performed at a bath temperature of 10 to 20 ° C., a cathode current density of 0.3 to 1.5 A / dm ² , an anode current density of 1.0 to 3.0 A / dm ² , and a liquid filtration circulation 5 to 6 times. Per hour.

(Acid soaking process)
By immersing the ABS resin base material on which the bright Sn plating layer is laminated in a sulfuric acid solution having various concentrations obtained by diluting an 80% by mass sulfuric acid solution with water, the acid immersion treatment is performed. The suitability value was examined. In the examination of the acid solution concentration, sulfuric acid solutions having respective concentrations of 4, 8, 12, 16, 20, and 40% by mass were used. Moreover, in the examination of the suitability value of the acid immersion treatment temperature, the immersion treatment was carried out at 25 ° C. and 50 ° C. for 5 minutes in sulfuric acid solutions having respective concentrations of 20, 40% by mass. Furthermore, in the examination of the suitability value of the acid immersion treatment time, the immersion treatment was carried out at 50 ° C. for 1, 2, and 3 minutes, respectively, in sulfuric acid solutions having respective concentrations of 20, 40% by mass. In any case, the acid rinsing treatment was performed using an 8% by mass sulfuric acid solution under conditions of an acid rinsing treatment temperature of 25 ° C. and an acid rinsing treatment time of 10 seconds.

(Acid rinsing process)
For the bright Sn plating layer on the ABS resin substrate after the acid immersion treatment, an acid rinse for a predetermined time at a predetermined temperature using a sulfuric acid solution of each concentration obtained by appropriately diluting an 80 mass% sulfuric acid solution with water. By performing the treatment, the suitability value of the acid rinsing treatment was examined. In the examination of the acid solution concentration, sulfuric acid solutions having concentrations of 0, 1, 4, and 8% by mass were used. In addition, in the examination of the appropriate value of the acid rinsing treatment temperature, the acid rinsing treatment was conducted for 10 seconds at 10 ° C., 25 ° C., and 50 ° C. in a sulfuric acid solution having a concentration of 8% by mass. Furthermore, in the examination of the suitability value of the acid rinsing treatment time, the acid rinsing treatment was carried out in an 8% by mass sulfuric acid solution at 25 ° C. for 10, 60 and 180 seconds, respectively. In any case, the acid immersion treatment was performed using a 20% by mass sulfuric acid solution under conditions of an acid immersion treatment temperature of 50 ° C. and an acid immersion treatment time of 5 minutes.

(Glossy Ni plating process)
A bright Ni plating layer was laminated on the bright Sn plating layer after the acid immersion treatment and the acid rinsing treatment. The bright Ni plating treatment can be performed in any of a Watt bath, a total chloride bath, a sulfamine bath, a wood strike bath, etc., but in this example, it was performed in a conventionally known Watt bath. As the brightener, an alkene sulfonate brightener (Hibright # 88, manufactured by Ebara Seisakusho) was used. The bath composition contains nickel sulfate (NiSO ₄ ) 250-300 g / L, nickel chloride (NiCl ₂ ) 40-60 g / L, boric acid 40-50 g / L, wetting agent, etc., and pH 3.8-4.6. The plating was performed under the conditions of a treatment temperature of 50 to 60 ° C., a cathode current density of 1.0 to 6.0 A / dm ² , and an anode current density of 0.5 to 3.0 A / dm ² .

(Microporous Ni plating process)
After laminating the bright Ni plating layer, a microporous Ni plating layer was further laminated thereon. The microporous Ni plating treatment is performed by dispersing and co-depositing inorganic fine particles in a nickel plating film in a bath to which insoluble inorganic fine particles (silica or the like) are added. The bath composition contains 280 g / L of nickel sulfate (NiSO ₄ ), 50 g / L of nickel chloride (NiCl ₂ ), and 40 g / L of boric acid. As the brightener, silica-based brightener (manufactured by Ebara Seisakusho, 3 mL of MP311) / L, MP333 10 mL / L) was used. The plating conditions were pH 4.4 to 4.8, treatment temperature 50 to 60 ° C., cathode current density 3.0 to 6.0 A / dm ² , and anode current density 1.5 to 3.0 A / dm ² .

(Cr plating process)
After laminating the microporous Ni plating layer, a Cr plating layer as the outermost layer was laminated thereon. Cr plating treatment can be any of Sargent bath, fluoride-containing bath (silica fluoride bath, SRHS bath), high speed bath, tetrachromate bath, trivalent chromium bath, high hardness chromium plating bath (Cr-C alloy plating bath), etc. However, in this example, it was performed in a conventionally known sergeant bath. The bath composition contains 200 to 300 g / L of chromic anhydride, 2 to 3 g / L of sulfuric acid (H ₂ SO ₄ ), and the plating process is performed under conditions of a bath temperature of 40 to 55 ° C. and a current density of 10 to 60 A / dm ^2. went.

(Evaluation by tape peeling test)
The tape peeling test method was performed by a method according to a cross-cut tape test (old JIS K5400). Specifically, eleven grooves in each of the vertical and horizontal directions are provided on the surface of the obtained laminated body at intervals of 2 mm to form 100 square grids. The cellophane tape was strongly pressure-bonded to the grid area, and then the cellophane tape was peeled off at a stretch, and the ratio of the area where peeling occurred on the surface of the laminate was determined in 100 grid grids to evaluate the adhesion.

Tables 1 and 2 show the results obtained by examining the suitability values of acid dipping treatment and acid rinsing treatment, respectively. In the evaluation column of Tables 1 and 2, the tape peeled area was 0%, 、２, 2% or less ◯, 5% or less △, and the others x.

From this result, when the concentration of the sulfuric acid solution is 20% by mass, the adhesion of the deposited layer to the bright Sn plating layer is very high at an acid immersion treatment temperature of 50 ° C. and an acid immersion treatment time of 3 minutes or more. When the amount was 40% by mass, it was found that the adhesion to the bright Sn plating layer was very high when the acid immersion treatment temperature was 50 ° C. and the acid immersion treatment time was 2 minutes or longer. By performing the acid immersion treatment at 50 ° C., the concentration of the sulfuric acid solution is 12% by mass or more, and the peeling area is 2% or less after 1 minute or more of the acid immersion treatment, and the adhesion of the deposited layer to the bright Sn plating layer is excellent. I found out.

As for the acid rinsing treatment, it can be seen that if the concentration of the sulfuric acid solution is 8% by mass or more, a laminate having excellent adhesion can be obtained even if the acid rinsing treatment temperature and the acid rinsing treatment time are arbitrary. It was.

(Evaluation of glossy Sn plating layer after sulfuric acid immersion treatment and adhesion evaluation with precipitation layer)
Changes in surface shape and surface components after sulfuric acid immersion treatment of the bright Sn plating layer has been confirmed to be effective in improving the adhesion between the bright Sn plating layer and the bright Ni plating layer. Was evaluated. The sulfuric acid immersion treatment was performed by immersing in a sulfuric acid solution of 8, 20, or 40% by mass at room temperature for 5 minutes. After an acid rinsing treatment with an 8% by mass sulfuric acid solution, the surface was washed with ethanol and dried, and immediately subjected to a sputtering treatment for evaluation.

The evaluation is based on the observation of the roughness of the surface of the bright Sn plating layer after sulfuric acid immersion treatment with a scanning electron microscope (SEM) and the component analysis of the oxygen ratio on the surface of the bright Sn plating layer by energy dispersive X-ray analysis (EDS). went. In addition, after performing the sulfuric acid immersion treatment under the same conditions, both the Ni plating treatment and the Cr plating treatment are performed under the above conditions, and by observing the occurrence of blisters on the surface of the obtained laminate, The adhesion with the deposited layer was evaluated. These results are shown in Table 3.

When the acid immersion treatment was performed in a sulfuric acid solution of 20% by mass or more, many rough surfaces of the bright Sn plating layer were observed. It is conceivable that surface oxygen is not detected in a region having a lot of surface roughness, and the oxide film is removed by acid immersion treatment with a sulfuric acid solution. In addition, it is considered that the occurrence of swelling after the Ni plating layer and the Cr plating layer are laminated is suppressed by surface roughness due to the sulfuric acid solution.

(Example 2)
It is the same as that of Example 1 except having replaced with the sulfuric acid solution and having performed the acid immersion process by the hydrochloric acid solution of the density | concentration of 1.75 mass% or 3.5 mass%, and not having performed the acid rinse process. Table 4 shows the evaluation results of the tape peel test.

The result of the tape peeling test when the acid immersion treatment with a 1.75 mass% hydrochloric acid solution was performed was 15%, and the result of the tape peeling test when the acid immersion treatment with a 3.5 mass% hydrochloric acid solution was performed. The result was 0%. It was found that when an acid immersion treatment was performed at 50 ° C. for 5 minutes using a 3.5 mass% hydrochloric acid solution, a laminate having excellent adhesion could be obtained.

Example 3
After performing an acid immersion treatment at 50 ° C. for 5 minutes with a sulfuric acid solution having a concentration of 20% by mass or 40% by mass, and an acid rinsing treatment at 25 ° C. for 10 seconds with an 8% by mass sulfuric acid solution, bright Ni plating treatment And the laminate obtained by performing the Cr plating treatment was evaluated for adhesion by a tape peeling test. The result showed that the adhesiveness of the laminate was excellent.

Example 4
In the same manner as in Example 1, the gloss Sn plating layer was laminated on the ABS resin base material subjected to electroless Ni plating treatment to give conductivity, and then acid dipping treatment and acid rinsing treatment were performed. Thereafter, a bright Ni plating process, a microporous Ni plating process, and a Cr plating process were sequentially performed to obtain a laminate. Except for the acid solution concentration, acid immersion treatment temperature, and acid immersion treatment time in the acid immersion treatment step, the other steps were performed under the same conditions as in Example 1. In the examination of the acid solution concentration, acid immersion treatment was performed on sulfuric acid solutions having respective concentrations of 25, 50, and 80 mass% at a treatment temperature of 50 ° C. for treatment times of 2, 5, 10, 20, and 30 minutes, respectively. The surface state of the bright Sn plating layer after the treatment was observed. In any case, the acid rinsing treatment was performed using an 8% by mass sulfuric acid solution under the conditions of an acid rinsing treatment temperature of 25 ° C. and an acid rinsing treatment time of 10 seconds.

In order to evaluate the physical shape of the surface of the bright Sn plating layer after the acid immersion treatment step, the surface was observed with a scanning electron microscope (SEM), and the fine shape of the surface of the bright Sn plating layer was measured with a surface roughness R ( μm) and waviness W (μm). Moreover, in order to evaluate the influence on the adhesiveness of the precipitation layer by an acid immersion process, the chipping test was done about the obtained laminated body.

The surface roughness R is a geometric amount that represents fine irregularities on the surface of the object, and is a parameter that represents the surface roughness from the roughness curve by obtaining a roughness curve of the object surface with a surface roughness measuring machine. It can be measured by calculating Since the surface roughness has a high frequency component in the shape of the object, the surface roughness is measured using a wide-area filter that passes only the high frequency component and cuts the low frequency component. On the other hand, the waviness W is a geometric amount that expresses unevenness larger than the surface roughness R, and has a frequency component lower than the surface roughness R. The waviness W is obtained from a filtered waviness curve obtained by removing a small concavo-convex component corresponding to the surface roughness from the cross-sectional curve of the object using a low-pass filter. The surface roughness R and waviness W were measured using a fine shape measuring instrument Surface corderET4000A manufactured by Kosaka Laboratory. The measurement conditions are based on JIS B0651: 2001. The measurement was performed under the conditions of a load of 100 μN, a speed of 50 μm / s, and a stylus R = 2 μm.

Also, in the chipping test, the chipping resistance of each laminate was evaluated based on the state of the laminate surface when 100 g of basalt No. 6 was blown horizontally with air at a pressure of 0.4 MPa and applied to the laminate. Measurement conditions are based on JIS Z8801-1. Furthermore, the adhesion between the bright Sn plating layer and the deposited layer was evaluated by observing the occurrence of swelling on the surface of each laminate. These results are shown in Table 5.

According to the surface observation of the bright Sn plating layer by SEM, the surface of the bright Sn plating layer is often roughened by immersing it in an 80% by weight sulfuric acid solution for 5 minutes or more, and the entire surface is uniformly uneven. It was. The surface of the bright Sn plating layer before the acid immersion treatment was smooth, whereas the surface treated with a 25% by mass sulfuric acid solution for 5 minutes, the one treated with a 50% by mass sulfuric acid solution for 5 minutes, 80% by mass No. 2 treated with sulfuric acid solution for 2 minutes was in a state where only a part of the surface of the bright Sn plating layer was dissolved.

FIGS. 1A to 1C show SEM photographs of the surface of the bright plating layer before and after the acid immersion treatment. It was found that the surface of the bright Sn plating layer that had been smooth before the acid immersion treatment was roughened by the acid immersion treatment for 5 minutes or longer with an 80% by mass sulfuric acid solution, and irregularities were generated on the entire surface. In the acid immersion treatment with an 80% by mass sulfuric acid solution, it was found that the treatment time was preferably 5 minutes or longer, more preferably 10 minutes or longer. However, in terms of the efficiency of manufacturing the laminate, if the treatment time exceeds 30 minutes, the acid immersion treatment requires a long time, which is not preferable.

Moreover, in the laminated body in which the precipitation layer was formed, the surface of the bright Sn plating layer was in a rough state, that is, the acid immersion treatment was performed for 5, 10, 20, or 30 minutes with an 80% by mass sulfuric acid solution. It was observed that the occurrence of swelling on the surface of the laminate was suppressed.

Further, when the surface microstructure of the bright Sn plating layer subjected to the acid dipping treatment under the same conditions as the laminate in which the occurrence of swelling is suppressed is measured with a Surface corderET4000A, the swell W is 0 to 0.04 (μm ) And the surface roughness R was in the range of 0.04 to 0.08 (μm). It was found that the surface condition of the bright Sn plating layer can be made excellent in adhesion to the deposited layer by performing the acid dipping treatment so that the undulation W and the surface roughness R are in this range.

According to the evaluation of the chipping resistance of each laminate, a high evaluation is obtained when the undulation W and the surface roughness R are within these ranges. From the results of the chipping test, it is 5 minutes with an 80% by mass sulfuric acid solution. By performing the acid immersion treatment as described above, it was confirmed that the surface of the bright Sn plating layer can be brought into a state excellent in adhesion with the deposited layer.

2 (A) to (C) show photographs of the surface after the chipping test of the laminate on which the deposited layer is formed. In the laminate in which the precipitation layer is formed without performing the acid immersion treatment, peeling is observed on the surface, whereas in the laminate in which the precipitation layer is formed by performing the acid immersion treatment with 80 mass% sulfuric acid for 5 minutes or more, It can be seen that peeling is suppressed and a lustrous appearance is imparted to the whole.

(Example 5)
The chipping resistance of the laminate formed with the deposited layer was examined from the viewpoint of the film thickness of the Ni plating layer laminated after the acid immersion treatment. Laminates having different Ni plating layer thicknesses were created, and a chipping test was performed on each laminate.

The ABS resin base material provided with conductivity by electroless Ni plating treatment was subjected to a bright Sn plating treatment, an acid dipping treatment and an acid rinsing treatment, and then a bright Ni plating treatment to obtain a laminate. The bright Sn plating treatment and the bright Ni plating treatment were performed under the same conditions as in Example 1. The acid immersion treatment was performed in a 25% by mass sulfuric acid solution at a treatment temperature of 50 ° C. under a treatment time of 5 minutes. The acid rinse treatment was conducted in an 8% by mass sulfuric acid solution at an acid treatment temperature of 25. It was performed under the conditions of ° C and a treatment time of 10 seconds.

In the bright Sn plating treatment, a bright Sn plating layer having a thickness of 10 μm was formed. In the bright Ni plating layer treatment, a bright Ni plating layer having a thickness of 1, 5 or 10 μm was formed. Each laminated body thus obtained was evaluated by a chipping test under the same test conditions as in Example 4 to determine whether or not the ABS resin as the base material was exposed. Moreover, while measuring the chipping depth (micrometer) of each laminated body surface after a chipping test, the Young's modulus (GPa) and surface hardness (N / mm < ² >) of the laminated glossy Ni plating layer were measured.

The measurement of the chipping depth was the same as the measurement condition of the surface roughness in Example 4, and was performed based on JIS B0651: 2001.
The Young's modulus and surface hardness were determined by measuring Martens hardness under measurement conditions based on ISO EN DIN14577 based on the indentation test method using Fixerscope H100CS manufactured by Fischer Instruments.

These results are shown in Table 6.

According to the result of the evaluation of chipping resistance, in the laminate in which the film thickness of the bright Ni plating layer was 1 μm or 5 μm, the bright Sn plating layer was damaged and the ABS resin as the base material was exposed. On the other hand, in the laminate in which the film thickness of the bright Ni plating layer was 10 μm, the ABS resin base material was not exposed.

In the laminated body after the chipping test, the chipping depth from the surface of the bright Ni plating layer was measured. In the laminated body with the thickness of the bright Ni plating layer being 10 μm, the depth of the hole was compared with the 1 μm or 5 μm laminated body. Was shallow. It is considered that the formation of deep holes is suppressed by the rigidity of the bright Ni plating layer.

Further, when the Young's modulus and surface hardness of the gloss Ni plating layer of each laminate were measured, the gloss Ni plating layer having a thickness of 10 μm had a Young's modulus of 44.66 GPa and a surface hardness of 2270.26 N / mm ^2. Met. When the Young's modulus and the surface hardness were these values, it was found that the ABS resin substrate was not exposed in the laminate and was excellent in chipping resistance.

The bright Sn plating layer has a ductility that can follow the ABS resin substrate and can give a bright appearance. However, since Sn is a relatively soft metal, the surface of the bright Sn plating layer is easily damaged. In this example, a bright Ni plating layer was laminated as a deposited layer to protect the bright Sn plating layer, and no ABS resin exposure was observed when the thickness of the bright Ni plating layer was 10 μm. Scratches are suppressed by the rigidity of the bright Ni plating layer, and Sn is extended on the ABS resin substrate by the bright Sn plating layer, and it is considered that the exposure of the ABS resin substrate is suppressed by the action of these layers. . The Young's modulus of the glossy Ni plating layer at this time is 44.66 GPa and the surface hardness is 2270.26 N / mm ² , which is different from the value in the glossy Ni plating layer in which the exposure of the ABS resin substrate was observed. Met. Therefore, it is considered that desired chipping resistance can be imparted to the laminate by setting the Young's modulus and surface hardness of the bright Ni plating layer within a predetermined range.

Moreover, since the bright Sn plating layer is subjected to acid dipping treatment, the surface of the bright Sn plating layer is in an excellent state of adhesion to the bright Ni plating layer, and between the bright Sn plating layer and the bright Ni plating layer. Delamination at the interface is suppressed. Also by this, it can be considered that desired chipping resistance can be imparted to the laminate, and exposure of the ABS resin substrate is suppressed.

Claims

A method for producing a laminate in which a deposited layer is electrically formed on a Sn plating layer laminated on the surface of a substrate,
In a plating bath containing a brightener and Sn, an Sn plating step of laminating a bright Sn plating layer made of Sn or an Sn alloy on a substrate;
After the Sn plating step, the bright Sn plating layer on the substrate is added to a sulfuric acid solution having a concentration of 10% by mass or more or a hydrochloric acid solution having a concentration of 3.5% by mass or more at 50 to 80 ° C. for 1 to 30%. An acid dipping process for dipping for a minute;
A deposited layer forming step for electrically forming a deposited layer on the bright Sn plating layer after the acid immersion treatment step;
The manufacturing method of the laminated body characterized by comprising.
2. The acid immersion treatment step is performed such that the surface of the bright Sn plating layer after the acid immersion treatment has a roughness of 0.040 to 0.080 μm and a undulation of 0 to 0.040 μm. The manufacturing method of the laminated body as described in any one of.
2. The method according to claim 1, further comprising an acid rinsing treatment step of rinsing the surface of the bright Sn plating layer on the substrate with an acid solution having a lower concentration than the acid solution used in the acid immersion treatment step after the acid immersion treatment step. The manufacturing method of the laminated body of 2.
The said acid rinse process process uses the acid of the same kind as the acid in the acid solution used at the said acid immersion process process, The manufacturing method of the laminated body of Claim 3 characterized by the above-mentioned.
The said base material is a manufacturing method of the laminated body as described in any one of Claims 1 thru | or 4 formed by performing an electroless-plating process to a synthetic resin.
A base material, a bright Sn plating layer laminated on the base material, and a deposited layer laminated on the bright Sn plating layer,
The bright Sn plating layer is made of Sn or Sn alloy containing a brightener,
A laminate having a surface roughness of the bright Sn plating layer of 0.040 to 0.080 μm and a undulation of 0 to 0.040 μm.