LAMINATE AND METHOD FOR MANUFACTURING LAMINATE

Abstract

To provide a laminate that can resist corrosion due to heat and light in comparison with the conventional art, and a method for producing a laminate that enables a silver layer to be deposited on a copper body at lower temperatures than in the conventional art.SOLUTION: The present invention discloses a laminate wherein: with a silver-containing oxidizer being in contact with a copper body, the oxidizer is reduced with an organic compound-containing reductant, so that a silver layer is deposited on the copper body. At an interface between the copper body and the silver layer, an alloy layer is formed that contains the copper component and the silver component; and on the surface of the silver layer, a protective layer is deposited that contains components of the reductant.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a laminate and a method for producing the laminate. [Background technology]

[0002] 2. Description of the Related Art Conventionally, techniques for forming a silver layer on a copper plate have been known (for example, Patent Documents 1 and 2). The silver-plated terminal for connectors in Patent Document 1 is formed by electroplating a silver plating layer on a copper plate. The silver-plated terminal for connectors in Patent Document 1 is formed by laminating a first silver plating layer and a second silver plating layer having a smaller crystal grain size than the first silver plating layer in this order on the surface of a base material made of copper or a copper alloy, and is said to be able to suppress the diffusion of copper components of the base material into the second silver plating layer and to suppress the oxidation of the copper components on the surface of the second silver plating layer.

[0003] In addition, in the method for producing silver described in Patent Document 2, silver oxide, 1,3-di-4-piperidylpropane, distilled water, and glass beads are pulverized and dispersed, the resulting dispersion is applied to a substrate, and a heat treatment is performed in an electric furnace at a temperature of 200° C., which is the decomposition temperature of silver oxide. This is said to form a silver layer on the substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-169408 A [Patent Document 2] JP 2004-58466 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the silver-plated terminal for connectors in Patent Document 1 has a problem in that the silver-plated layer is easily corroded by heat and light because the silver-plated layer is formed on the surface. When the silver-plated layer corrodes, the resistance increases and the layer turns black, which may result in a poor appearance. Furthermore, the silver production method of Patent Document 2 requires heating to a high temperature of 200° C. or higher, which is said to be the temperature at which silver oxide begins to decompose, and this places significant limitations on the applications in which it can be used.

[0006] Therefore, an object of the present invention is to provide a laminate that can suppress corrosion due to heat and light compared to conventional methods, and a method for producing a laminate that can laminate a silver layer on a copper body at a lower temperature compared to conventional methods. [Means for solving the problem]

[0007] One aspect of the present invention for solving the above-mentioned problems is a laminate in which an oxidizing agent containing silver is brought into contact with a copper body, the oxidizing agent being reduced by a reducing agent containing an organic compound, and a silver layer is laminated on the copper body, wherein an alloy layer containing a copper component and a silver component is formed at the interface between the copper body and the silver layer, and a protective layer containing a component of the reducing agent is laminated on the surface of the silver layer.

[0008] According to this aspect, since an alloy layer is formed at the interface between the copper body and the silver layer, the interfacial resistance between the copper body and the silver layer can be reduced. According to this aspect, since a protective layer is formed on the surface of the silver layer, oxidation of the silver layer due to light or heat can be suppressed. According to this aspect, since the protective layer is a layer derived from a reducing agent, there is no need to provide a separate protective layer, and the effect of inhibiting oxidation of the silver layer can be achieved at low cost.

[0009] In a preferred aspect, the protective layer contains a compound having at least one of a 2,2,6,6-tetraalkylpiperidinyl group and a 1,2,2,6,6-pentaalkylpiperidinyl group.

[0010] According to this aspect, it is possible to provide better corrosion resistance against heat and light.

[0011] In a preferred aspect, the alloy layer has a ratio of silver to copper of 2 / 3 or more and 3 / 2 or less.

[0012] In a preferred aspect, when an electron beam diffraction image of the alloy layer is obtained, the pattern of the electron beam diffraction image coincides with a simulation pattern of an electron beam diffraction image of a 1:1 alloy of copper and silver components in the space group Fm-3m.

[0013] In a preferred aspect, the average thickness of the alloy layer is 30% to 60% of the average thickness of the silver layer.

[0014] The term "average film thickness" used herein refers to the arithmetic mean value of film thickness at any three points. The same applies hereinafter.

[0015] In a preferred aspect, a residue layer containing a component derived from the reducing agent is formed at the interface between the alloy layer and the silver layer.

[0016] In a more preferred aspect, a void portion is present adjacent to the silver layer at the interface between the alloy layer and the silver layer, and at least a portion of the inner wall of the void portion is constituted by the residue layer.

[0017] In a preferred aspect, the oxidizing agent is silver oxide.

[0018] In a preferred aspect, the reducing agent is a hindered amine light stabilizer.

[0019] In a preferred aspect, the reducing agent includes a hindered amine compound having two or more of at least one of a 2,2,6,6-tetraalkylpiperidinyl group and a 1,2,2,6,6-pentaalkylpiperidinyl group and having a molecular weight of 700 or less.

[0020] In a preferred aspect, the oxidizing agent is silver oxide.

[0021] One aspect of the present invention is a laminate having a silver layer laminated on a copper body, wherein an alloy layer containing a copper component and a silver component is formed at the interface between the copper body and the silver layer, and a protective layer containing a compound having a 2,2,6,6-tetraalkylpiperidinyl group or a 1,2,2,6,6-pentaalkylpiperidinyl group is laminated on the surface of the silver layer.

[0022] According to this aspect, since an alloy layer is formed at the interface between the copper body and the silver layer, the interfacial resistance between the copper body and the silver layer can be reduced. According to this aspect, a protective layer containing a compound having a 2,2,6,6-tetraalkylpiperidinyl group or a 1,2,2,6,6-pentaalkylpiperidinyl group is formed on the surface of the silver layer, thereby suppressing corrosion of the silver layer due to light or heat and improving durability.

[0023] As a result of extensive research by the present inventors into reducing agents that reduce silver oxide, it was discovered that by using a hindered amine light stabilizer, which has traditionally been used as a light stabilizer for resins but not as a reducing agent for inorganic metals, as a reducing agent, it is possible to reduce silver oxide and form a silver layer at a temperature lower than 200°C, which has traditionally been considered the decomposition starting temperature of general silver oxide.

[0024] One aspect of the present invention derived from this discovery is a method for producing a laminate, comprising: a mixing step of mixing a reducing agent and silver oxide to form a mixture; a coating step of coating the mixture onto a copper body; and a heating step of heating the copper body to which the mixture has been coated at a first heating temperature, wherein the reducing agent is a hindered amine light stabilizer, and the first heating temperature is less than 200°C.

[0025] According to this aspect, the silver layer can be formed by reducing silver oxide at a temperature lower than the decomposition temperature of general silver oxide, and the laminate can be easily formed.

[0026] One aspect of the present invention is a method for producing a laminate, the method comprising: mixing a reducing agent and silver oxide to form a mixture; applying the mixture onto a copper body; and heating the copper body to which the mixture has been applied at a first heating temperature, the reducing agent comprising a hindered amine compound having at least one of a 2,2,6,6-tetraalkylpiperidinyl group and a 1,2,2,6,6-pentaalkylpiperidinyl group, and the first heating temperature being less than 200° C.

[0027] According to this aspect, the silver layer can be formed by reducing silver oxide at a temperature lower than the decomposition temperature of general silver oxide, and the laminate can be easily formed. Effect of the Invention

[0028] According to the laminate of the present invention, corrosion caused by heat and light can be suppressed more effectively than in the past. According to the method for producing a laminate of the present invention, a silver layer can be laminated on a copper body at a lower temperature than in the past. [Brief description of the drawings]

[0029] [Figure 1] 1 is a cross-sectional view of a laminate according to a first embodiment of the present invention. [Diagram 2] 1 shows the results of STEM observation of Experimental Example 1, where (a) is a low-magnification STEM image and (b) is a traced drawing of (a). [Diagram 3] 1 shows the results of STEM observation of Experimental Example 1, where (a) is a high-magnification STEM image and (b) is a traced drawing of (a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, an embodiment of the present invention will be described in detail.

[0031] The laminate 1 of the first embodiment of the present invention is suitable for use as a reflective film for organic EL displays, liquid crystal displays, and the like, conductive materials such as wiring and electrodes, decorative materials, recording materials, antibacterial materials, and the like. 1, the laminate 1 is a multilayer structure in which an alloy layer 3 and a silver layer 5 are laminated in this order on a copper plate 2 (copper body). That is, in the laminate 1, the alloy layer 3 is interposed between the copper plate 2 and the silver layer 5. 1, in the laminate 1, a residual layer 6 is formed on the surface of the alloy layer 3 at the interface between the alloy layer 3 and the silver layer 5, and a protective layer 7 is formed on the surface of the silver layer 5. In the laminate 1, a plurality of voids 8 are formed at the interface between the alloy layer 3 and the silver layer 5 as shown in FIG.

[0032] The copper plate 2 is a planar copper plate having a first main surface and a second main surface, and serves as a supporting substrate that supports the silver layer 5 on the first main surface. The copper plate 2 has different surface roughness between the first main surface 10 and the second main surface 11, with surface irregularities formed on the first main surface 10 and the surface roughness of the first main surface 10 being greater than the surface roughness of the second main surface 11.

[0033] The alloy layer 3 is formed on the copper plate 2 and is a copper-silver alloy layer containing a copper component and a silver component. In the alloy layer 3, the ratio of the silver component to the copper component is preferably 2 / 3 or more and 3 / 2 or less. The average thickness of the alloy layer 3 is thinner than that of the silver layer 5, and is preferably 10% to 90%, more preferably 20% to 60%, of the average thickness of the silver layer 5. The average film thickness of the alloy layer 3 can be determined, for example, by observing a cross section of the alloy layer 3 using a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and calculating the arithmetic average value at any three points. The alloy layer 3 preferably contains a copper component and a silver component in a 1:1 ratio and has a crystal structure of the space group Fm-3m.

[0034] The silver layer 5 is a thin silver layer formed on the alloy layer 3 . The average thickness of the silver layer 5 is 1 μm or less, and from the viewpoint of ensuring sufficient electrical conductivity, it is preferably 50 nm or more and 500 nm or less, and more preferably 150 nm or more and 300 nm or less. The average film thickness of the silver layer 5 can be determined, for example, by observing a cross section of the silver layer 5 with a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and calculating the arithmetic average value at any three points.

[0035] The residue layer 6 is a layer formed on the surface of the alloy layer 3 . The residue layer 6 contains a component derived from a reducing agent used in the manufacturing method of the laminate 1 described below, and is mainly composed of residues generated during the manufacturing process of the laminate 1. The term "major component" here refers to a component that accounts for more than 50% of the total. The residue layer 6 of this embodiment contains carbon elements derived from the reducing agent. The average thickness of the residual layer 6 is preferably 1 nm or more and 20 nm or less. If it is in this range, electrical conduction between the alloy layer 3 and the silver layer 5 is not easily hindered.

[0036] The protective layer 7 has light stability and heat stability, and protects the silver layer 5 from light and heat. The protective layer 7 is a layer derived from the reducing agent used to form the silver layer 5 in the manufacturing method of the laminate 1 described later, and is composed of the product of the reducing agent reacted with an oxidizing agent or unreacted reducing agent. The protective layer 7 of this embodiment contains a compound having at least one of a 2,2,6,6-tetraalkylpiperidinyl group and a 1,2,2,6,6-pentaalkylpiperidinyl group. The number of 1,2,2,6,6-pentaalkylpiperidinyl groups and 2,2,6,6-tetraalkylpiperidinyl groups in this compound is not particularly limited. In this compound, the alkyl groups in the 1,2,2,6,6-pentaalkylpiperidinyl group and the 2,2,6,6-tetraalkylpiperidinyl group each preferably have 1 to 4 carbon atoms.

[0037] The average thickness of the protective layer 7 is preferably 1 nm or more and 20 nm or less. If it is in this range, the silver layer 5 can be sufficiently protected from light and heat. The average film thickness of the protective layer 7 can be obtained, for example, by observing a cross section of the protective layer 7 with a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and calculating the arithmetic average value at any three points.

[0038] The voids 8 are voids originating from gaps between the silver particles constituting the silver layer 5 and gaps between the silver particles and the copper plate 2 . Each of the voids 8 is biased toward the silver layer 5 and is provided adjacent to the silver layer 5 . In this embodiment, the voids 8 are preferably 0.5 nm or more and 30 nm or less.

[0039] Next, a method for producing the laminate 1 of this embodiment will be described.

[0040] The method for manufacturing the laminate 1 of this embodiment involves reducing an oxidizing agent containing silver with a reducing agent containing an organic compound in contact with a copper plate 2, and laminating a silver layer 5 on the copper plate 2. The oxidizing agent is not particularly limited as long as it contains silver and functions as an oxidizing agent in relation to the reducing agent. For example, silver oxide, silver carbonate, silver acetate, and silver acetylacetone complex can be used as the oxidizing agent. In the following description, a case where silver oxide is used as an example of an oxidizing agent will be described.

[0041] First, silver oxide is mixed with a reducing agent to form a mixture (mixing step).

[0042] In this case, the reducing agent is an amine-based reducing agent, and is preferably a hindered amine-based light stabilizer having at least one of a 1,2,2,6,6-pentaalkylpiperidinyl group and a 2,2,6,6-tetraalkylpiperidinyl group, and more preferably an N-CH3-type or NH-type hindered amine-based light stabilizer. As the N-CH3 type hindered amine light stabilizer, Bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate or the like can be used. Examples of the NH-type hindered amine light stabilizer that can be used include Tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate, Tetrakis(2,2,6,6-tetramethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate, and Bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate. From another viewpoint, the reducing agent preferably contains a hindered amine compound having two or more of at least one of 2,2,6,6-tetraalkylpiperidinyl groups and 1,2,2,6,6-pentaalkylpiperidinyl groups and having a molecular weight of 700 or less. In this hindered amine compound, the carbon at the 4-position of the piperidine ring of the 1,2,2,6,6-pentaalkylpiperidinyl group or 2,2,6,6-tetraalkylpiperidinyl group preferably forms an ester bond with a carboxylic acid. The number of 1,2,2,6,6-pentaalkylpiperidinyl groups and 2,2,6,6-tetraalkylpiperidinyl groups in this hindered amine compound is not particularly limited. In addition, it is preferable that the alkyl groups in the 1,2,2,6,6-pentaalkylpiperidinyl group and the 2,2,6,6-tetraalkylpiperidinyl group each independently have 1 to 4 carbon atoms. The reducing agent may be solid or liquid at room temperature, but it preferably has a melting point lower than the first heating temperature in the heating step described below. If the melting point of these amine compounds is lower than the first heating temperature, when the reducing agent is heated together with silver oxide in the heating step described below, even if the reducing agent is solid, the reducing agent melts and becomes liquid before the first heating temperature is reached, so that the contact area with the silver oxide is increased and the reduction of the silver oxide can be performed efficiently. In this embodiment, the reducing agent contains an amine compound having the following structural formula (1).

[0043] [ka]

[0044] In the above structural formula (1), R 1 and R 2 each independently represents a hydrogen atom or a methyl group, and p is a positive integer of 1 or more and 18 or less.

[0045] Subsequently, the mixture obtained through the mixing step is applied to a desired area on the first main surface of the copper plate 2 (application step).

[0046] The coating method is not particularly limited, and examples thereof include casting, roll coating, bar coating, die coating, spin coating, spray coating, and dip coating.

[0047] Subsequently, the copper plate 2 on which the mixture has been applied is placed in a heating device and heated at a first heating temperature, and the silver oxide is reduced with a reducing agent to form a silver layer 5 on the copper plate 2 (heating step).

[0048] The first heating temperature in this case is not particularly limited as long as it is a temperature at which the reaction between the silver oxide and the reducing agent proceeds, but from the viewpoint of reducing the silver oxide in a short period of time, it is preferably 100°C or higher and lower than 200°C, and more preferably 120°C or higher and 180°C or lower. At this time, on the surface of the copper plate 2, the copper component diffuses toward the silver layer 5, forming an alloy layer 3 with the silver layer 5, and a residue layer 6 of part of the reducing agent that has reacted with the oxidizing agent is formed on the surface of the alloy layer 3. In addition, at the interface between the alloy layer 3 and the silver layer 5, voids 8 are formed that correspond to the gaps between the silver particles that make up the silver layer 5 and the gaps between the silver particles and the copper plate 2. A protective layer 7 is formed on the surface of the silver layer 5 by covering a part of the reducing agent that has reacted with the oxidizing agent or by covering the unreacted reducing agent.

[0049] Next, the copper plate 2 on which the silver layer 5 has been formed is washed with a washing solvent (washing step).

[0050] The cleaning solvent used in this case is not particularly limited as long as it does not substantially react with silver, and for example, a volatile organic solvent such as acetone can be used.

[0051] According to the laminate 1 of the first embodiment, since the alloy layer 3 is formed at the interface between the copper plate 2 and the silver layer 5, the interface resistance between the copper plate 2 and the silver layer 5 can be reduced. According to the laminate 1 of the first embodiment, since the protective layer 7 is formed on the surface of the silver layer 5, oxidation of the silver layer 5 and the like can be suppressed. According to the laminate 1 of the first embodiment, the protective layer 7 formed on the surface of the silver layer 5 contains a compound having a 2,2,6,6-tetraalkylpiperidinyl group or a 1,2,2,6,6-pentaalkylpiperidinyl group, so that corrosion of the silver layer 5 due to light or heat can be suppressed and durability can be improved.

[0052] According to the method for producing the laminate 1 of the first embodiment, the silver layer 5 can be formed by reducing silver oxide at a temperature lower than the decomposition temperature of typical silver oxide, and the laminate 1 can be easily formed.

[0053] In the above embodiment, the silver layer 5 is formed on the first main surface 10 of the copper plate 2, but the present invention is not limited to this. The silver layer 5 may be formed on both sides 10, 11 of the copper plate 2. That is, the silver layer 5 may be formed on the first main surface 10 and the second main surface 11 of the copper plate 2.

[0054] In the above embodiment, the copper plate 2 is used as the copper body supporting the silver layer 5, but the present invention is not limited to this. The copper body may be a copper layer laminated on a support. For example, the copper body may be a glass substrate on which a copper layer is laminated.

[0055] In the above embodiment, a case has been described in which the plate-shaped copper plate 2 is used as the copper body supporting the silver layer 5, but the present invention is not limited to this. A film-shaped or sheet-shaped body such as a copper foil or a copper sheet may also be used.

[0056] In the above-described embodiments, each component may be freely substituted or added between the respective embodiments as long as it falls within the technical scope of the present invention. EXAMPLES

[0057] The present invention will be specifically described below with reference to various experimental examples as examples, but the present invention is not limited to these experimental examples.

[0058] (Experimental Example 1) In Experimental Example 1, 100 parts by weight of silver oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade silver oxide, maximum particle size 10 μm) and 100 parts by mass of liquid bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (manufactured by ADEKA Corporation, Adeka STAB LA-72) were mixed to obtain a paste-like mixture. The mixture was then applied to a copper substrate over an area of ​​5 cm x 5 cm and held at 150° C. for 60 minutes. The surface of the mixture on the copper substrate was then washed with acetone to obtain a silver film adhered to the copper substrate. The laminate thus obtained was used as Experimental Example 1.

[0059] (Experimental Example 2) Experimental Example 2 was conducted in the same manner as in Experimental Example 1, except that solid bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (ADEKA CORPORATION, Adeka STAB LA-77Y, melting point 82° C. to 87° C.) was used as the reducing agent.

[0060] (STEM observation) In Experimental Example 1, cross-section processing was performed using a focused ion beam (FIB), and the cross-section was observed using a scanning transmission electron microscope (STEM) (Hitachi High-Technologies Corporation, HD-2700) and subjected to elemental analysis using energy dispersive X-ray analysis (EDX). In addition, in Experimental Example 1, an electron beam diffraction image was observed, and a simulation of the electron beam diffraction image was performed based on the crystal database of Mat Navi (https: / / mits.nims.go.jp / ). The electron beam diffraction image of Example 1 was overlaid on the simulation pattern for identification.

[0061] FIG. 2(a) shows a low-magnification STEM secondary electron image (hereinafter also referred to as SE image) in Experimental Example 1, and FIG. 2(b) shows a trace of the SE image in FIG. 2(a). FIG. 3(a) shows a high-magnification STEM transmission electron image (hereinafter also referred to as a TE image) in Experimental Example 1, and FIG. 3(b) shows a trace of the TE image in FIG. 3(a). In Experimental Example 1, when the SE image was observed as in Figure 2, a silver-copper alloy layer was confirmed between the copper substrate and the silver layer, and multiple voids were formed on the silver layer side of the alloy layer. Similarly, in Experimental Example 2, when the SE image was observed, an alloy layer of silver and copper was confirmed between the copper substrate and the silver layer, and a plurality of voids were formed on the silver layer side of the alloy layer. In Experimental Example 1, when a high-magnification TE image was observed as in Figure 3, a silver-copper alloy layer was confirmed between the copper substrate and the silver layer, and a protective layer of several nm to several tens of nm originating from the reducing agent was confirmed on the surface of the silver layer. In addition, a residue layer was confirmed between the alloy layer and the silver layer. When elemental analysis was performed by EDX at measurement points 1 to 6 shown in FIG. 3(b), a silver peak was detected at measurement point 2, which corresponds to the position of the silver layer, but no carbon or nitrogen peaks were detected. Meanwhile, at measurement point 1, which corresponds to the position of the protective layer, not only a silver peak but also carbon and nitrogen peaks were detected. At measurement point 4, which corresponds to the alloy layer, peaks for silver, copper, and carbon were detected, but no nitrogen peak was detected. At measurement point 3, which corresponds to the position of the residue layer, peaks for silver, copper, and carbon were detected, as at measurement point 4, but no nitrogen peak was detected. However, a larger carbon peak was detected than at measurement point 4, and the amount of carbon detected was greater. At measurement point 5, which corresponds to the position of the interface between the alloy layer and the copper substrate, and measurement point 6, which corresponds to the position of the copper substrate, a copper peak was detected, but no nitrogen peak was detected.

[0062] In Experimental Example 1, electron diffraction was performed at measurement point 4 shown in FIG. 3(b) and the electron diffraction image was observed. The pattern of the electron diffraction image was roughly consistent with the simulation pattern of a copper-silver alloy with a 1:1 ratio of copper and silver components. The simulation pattern of this copper-silver alloy was calculated based on the crystal structure (space group number 225, crystal structure of space group Fm-3m (a = 0.38765 nm, b = 0.38765 nm, c = 0.38765 nm, α = 90°, β = 90°, γ = 90°).

[0063] Since a nitrogen peak and a carbon peak were detected in the results of measurement point 1, it was presumed that heating caused the reducing agent residue to bleed out on the surface of the thin silver film layer, forming a protective layer on the thin silver film layer that contained a compound with a 1,2,2,6,6-pentaalkylpiperidinyl group derived from the reducing agent. The results from measurement point 4 showed that a large amount of carbon was detected in the adjacent silver layer and alloy layer, and that a lighter colored area was confirmed between the alloy layer and the thin silver film layer in the TE image. This suggested that a light metal layer had been formed between the silver layer and the alloy layer as a residue layer due to the reduction agent being oxidized and decomposed.

[0064] To summarise the above, the results are as follows: (1) The results of STEM observations showed that the use of an N-CH3-type hindered amine light stabilizer having a 1,2,2,6,6-pentaalkylpiperidinyl group or an NH-type hindered amine light stabilizer having a 2,2,6,6-tetraalkylpiperidinyl group as a reducing agent enabled the reduction of silver oxide on a copper substrate to form a nanometer-order thin silver film layer. (2) The results of STEM observation confirmed that the use of a hindered amine light stabilizer as a reducing agent can reduce silver oxide on the copper substrate to form a thin silver film layer, and also that a protective layer is formed on the surface of the thin silver film layer and a residue layer is formed on the surface of the alloy layer. The results of EDX analysis suggested that the protective layer on the surface of the silver layer and the residue layer at the interface between the silver layer and the alloy layer are derived from the reducing agent. [Explanation of symbols]

[0065] 1. Laminate 2 Copper plate (copper body) 3 alloy layer 6 Residue layer 5 silver layer 7 Protective layer 8 Cavity

Claims

1. A laminate in which an oxidizing agent containing silver is heated in contact with a copper body, the oxidizing agent is reduced by a reducing agent containing an organic compound, and a silver layer is laminated on the copper body, an alloy layer containing a copper component and a silver component is formed at the interface between the copper body and the silver layer, the reducing agent is a hindered amine-based light stabilizer having at least one of a 2,2,6,6-tetraalkylpiperidinyl group and a 1,2,2,6,6-pentaalkylpiperidinyl group, a protective layer containing a compound having at least one of a 2,2,6,6-tetraalkylpiperidinyl group and a 1,2,2,6,6-pentaalkylpiperidinyl group is laminated on the surface of the silver layer; a residue layer containing a component derived from the reducing agent is formed at the interface between the alloy layer and the silver layer.

2. 2. The laminate according to claim 1, wherein when an electron beam diffraction image of the alloy layer is obtained, the pattern of the electron beam diffraction image coincides with a simulation pattern of an electron beam diffraction image of a 1:1 alloy of copper and silver components in space group Fm-3m.

3. 3. The laminate according to claim 1, wherein the average thickness of the alloy layer is 30% or more and 60% or less of the average thickness of the silver layer.

4. a void portion adjacent to the silver layer is present at the interface between the alloy layer and the silver layer, The laminate according to any one of claims 1 to 3, wherein at least a portion of the inner wall of the gap is constituted by the residual layer.

5. The laminate according to any one of claims 1 to 4, wherein the oxidizing agent is silver oxide.

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