JP2011178019A - Laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate containing a metal thin film precursor capable of forming a metal thin film having few pin holes and remarkably low resistance equal to that of a bulk metal by heat-treating after a protective film is peeled off. <P>SOLUTION: The laminate is provided with a composite layer containing the metal thin film precursor and a polyether compound and the protective film laminated on at least one surface of the composite layer. The adhesive strength between the composite layer and the protective film is ≤0.2 kN/m. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laminate including a metal precursor suitably used for an electric wiring circuit board such as a printed wiring board, a bonding material, or the like.

  Conventionally, plating methods, vacuum deposition methods, sputtering methods, CVD methods, metal paste methods, and the like are known as methods for forming a metal thin film on a substrate.

  In the plating method, it is possible to form a metal thin film relatively easily on a conductive substrate. However, when forming a metal thin film on an insulating substrate, the conductive layer is formed first. There is a need to. For this reason, there is a problem that the process becomes complicated. In addition, the plating method uses a reaction in a solution, so that a large amount of waste liquid is produced as a by-product, and there is a problem that this waste liquid treatment requires a lot of labor and cost. Not enough.

  Vapor deposition methods such as vacuum deposition, sputtering, and CVD all require expensive vacuum equipment, and all have the problem of slow deposition rates. Further, in these gas phase methods in which metals in an atomic state are stacked in a film form, there is a concern that so-called pinholes in which the metal does not adhere due to slight unevenness or dirt on the surface are likely to occur.

In these vapor phase methods, the surface of the substrate is usually subjected to a surface treatment such as plasma treatment before the metal thin film is formed, and the substrate may be damaged by this surface treatment. For example, Patent Document 1 discloses that when a polyimide film is subjected to plasma treatment, an imide ring in a surface layer is cleaved, and oxygen functional groups and nitrogen functional groups are generated due to differences in oxygen concentration conditions. In Patent Document 1, after performing plasma treatment under the condition of oxygen concentration (1 to 10) × 10 ⁻⁶ Pa, the initial adhesive strength is 1 kgf due to the interaction between the nitrogen functional group and copper by vapor deposition of copper. It is disclosed that a laminate of about / cm is obtained, and the heat treatment at 150 ° C. × 24 h to 168 h strengthens the interaction with copper oxide and increases the adhesive strength to 1.2 kgf / cm to 1.8 kgf / cm. Has been. However, in the plasma treatment, since a nitrogen functional group generated by modification of polyimide is generated, there is a concern that film physical properties are deteriorated such as a decrease in heat resistance of the polyimide film and an increase in hygroscopicity.

  The metal paste method is a method in which a metal thin film is obtained by applying a solution in which a metal filler is dispersed onto an insulating substrate, and performing heat treatment. This method does not require a special apparatus such as a vacuum apparatus and has an advantage that the process is simple, and further has an advantage that the generation of pinholes as in the vapor phase method can be suppressed. However, in order to melt the metal filler, a high temperature of 1000 ° C. or higher is usually required. For this reason, the base material is limited to those having heat resistance such as a ceramic base material, and there is a problem that the base material is damaged by heat or the base material is easily damaged by residual stress generated by heating. Furthermore, the adhesion of the resulting metal thin film to the substrate is not sufficient.

  Patent Document 2 discloses that adhesion to a substrate is improved by applying a mixture of metal powder and a reactive organic medium onto a coating layer that is a diffusion and adhesion barrier of soluble polyimide or the like and heat-treating the mixture. Is disclosed. Further, in Patent Document 2, for example, when a copper film is formed from a mixture of copper powder and a copper-based reactive organic medium, a protective atmosphere (a nitrogen atmosphere or an oxygen concentration of less than 3 ppm or hydrogen is used to prevent copper oxidation). It is disclosed that a heat treatment in a reducing atmosphere) is preferable, and in that case, it is possible to obtain a fixing property to the extent that the tape test is cleared. However, the adhesive strength is about 1 kgf / cm, which is not sufficient. In addition, since metal powder of 2 μm to 10 μm is used, the interface roughness between the metal film and the substrate is large, and there is a concern that it is difficult to form fine wiring in applications where the metal film is formed by photolithography.

  On the other hand, a technique for reducing the firing temperature of the metal paste by reducing the particle size of the metal filler is known. For example, Patent Document 3 discloses a method of directly forming a metal thin film on an insulating substrate using a dispersion in which metal fine particles having a particle diameter of 100 nm or less are dispersed. However, the adhesion of the metal thin film prepared by this method to the insulating substrate is not sufficient. Furthermore, the method for producing metal particles of 100 nm or less used here is a method of rapidly cooling metal vapor volatilized in a low-pressure atmosphere, so that mass production is difficult and the cost of the metal filler is increased. Have.

  A method of forming a metal thin film directly on an insulating substrate using a metal oxide paste in which a metal oxide filler is dispersed is also known. Patent Document 4 discloses a method of obtaining a metal thin film by heating a metal oxide paste containing a crystalline polymer and dispersing a metal oxide having a particle size of 300 nm or less to decompose the crystalline polymer. . However, in this method, it is necessary to disperse a metal oxide of 300 nm or less in the crystalline polymer in advance, and in addition to requiring a great effort, 400 ° C. to 900 ° C. is necessary for decomposing the crystalline polymer. Need high temperature. For this reason, the base material which can be used requires the heat resistance more than the temperature, and there exists a problem that the kind has a restriction | limiting. Further, the adhesion of the obtained metal thin film to the substrate is not sufficient.

  As a method of manufacturing a metal thin film that solves these problems, the present applicant has already applied a dispersion in which an inexpensive metal oxide filler is dispersed on a substrate, and then applied the metal thin film by heat treatment at a relatively low temperature. The method of obtaining is disclosed (Patent Document 5). With this technology, it is possible to easily form a thin metal film such as thin copper, etc. on a substrate, and to form a copper film on a polyimide film as a substrate, and to use it as a flexible circuit board material. Is possible. Furthermore, it is required to realize a laminate including a metal thin film precursor that can form a metal thin film with few pinholes and a very low resistance value similar to that of bulk metal by heat treatment after peeling off the protective film. It was.

JP 2005-54259 A Special table 2003-506882 gazette Japanese Patent No. 2561537 Japanese Patent Laid-Open No. 5-98195 JP 2008-200557 A

  The present invention has been made in view of the above points, and a metal thin film precursor capable of forming a metal thin film having a very low resistance value equivalent to that of a bulk metal by heat treatment after peeling of the protective film with few pinholes. It aims at providing the laminated body containing this.

  As a result of diligent investigations to solve the above problems, the present inventors have completed the present invention. That is, the present invention is as follows.

  The laminate of the present invention comprises a composite layer containing a metal thin film precursor and a polyether compound, and a protective film laminated on at least one surface of the composite layer, the composite layer and the protective film, The adhesion strength is 0.2 kN / m or less.

  In the laminated body of this invention, it is preferable that the content rate of the said polyether compound with respect to the said metal thin film precursor in the said composite layer exists in the range of 0.05-0.30 by weight ratio.

  In the laminate of the present invention, the metal thin film precursor is preferably at least one metal thin film precursor particle selected from the group consisting of metal particles, metal oxide particles, and metal hydroxide particles.

  In the laminate of the present invention, the primary particle diameter of the metal thin film precursor particles is preferably 200 nm or less.

  In the laminate of the present invention, the metal thin film precursor is preferably cuprous oxide particles.

  In the laminate of the present invention, it is preferable that the surface of the protective film in contact with the composite layer is surface-treated with a peelable compound.

  In the laminate of the present invention, the peelable compound is preferably a silicone compound.

  In the laminate of the present invention, the polyether compound is preferably a linear aliphatic polyether compound.

  In the laminate of the present invention, the linear aliphatic polyether compound preferably has a molecular weight of 150 to 600 and has an alkyl group at one end.

  The metal thin film of the present invention is obtained by peeling off the protective film from the laminate and then heat-treating it.

  The metal bonding material of the present invention is characterized in that the protective film is peeled off from the laminate and is then heat-treated by being sandwiched between metal-coated surfaces.

  According to the present invention, it is possible to provide a laminate including a metal thin film precursor that can form a metal thin film with few pinholes and a very low resistance value similar to that of a bulk metal by heat treatment after the protective film is peeled off. Can do.

Hereinafter, embodiments of the present invention will be described in detail.
A laminate according to the present invention is a laminate including a composite layer containing a metal thin film precursor and a polyether compound, and a protective film is laminated on at least one surface of the composite layer, and the composite layer and the protective layer are protected. The adhesion strength with the film is 0.2 kN / m or less.

  Metal obtained by heat treatment without causing the composite layer to undergo cohesive failure when the protective film is peeled off from the composite layer because the adhesion strength between the composite layer and the protective film is 0.2 kN / m or less The frequency of pinholes entering the thin film can be suppressed. Here, the cohesive failure is a phenomenon in which a part of the composite layer is peeled off from the layer when the cardboard is peeled from the composite layer. As described above, when the composite layer is coherently broken, defects such as pinholes are generated in the metal thin film. In the present invention, when the adhesion strength between the composite layer and the cardboard is 0.2 Nk / m or less, when the cardboard is peeled from the composite layer, the adhesion force of the compound constituting the composite layer to the protective film is appropriate. Therefore, the cohesive failure of the composite layer can be suppressed, and the generation of defects such as pinholes in the metal thin film can be suppressed. Moreover, the low resistance value of the obtained metal thin film can be achieved by suppressing the occurrence of defects such as pinholes. The lower limit value of the adhesion strength is not particularly limited as long as it does not have difficulty in winding the laminate.

  The metal thin film precursor is a compound that can form a metal thin film by post-treatment such as heat treatment. Examples of the metal thin film precursor include metal thin film precursor particles that are fused to each other by heat treatment, and metal complexes that are reduced to metal by heat treatment to form a metal thin film.

  Metal thin film precursor particles that are fused to each other by heat treatment are: a dispersion containing metal thin film precursor particles is applied in the form of a film and heated, so that the metal particles are joined to each other and appear to be continuous. It is the particle | grains which form the metal thin film formed with the metal layer.

  From the viewpoint of ensuring high dispersibility and obtaining a dense metal thin film by heat treatment, the metal thin film precursor particles preferably have a primary particle diameter of 200 nm or less, more preferably 100 nm or less, and even more preferably 30 nm or less. Moreover, it is preferable that a primary particle diameter is 1 nm or more from a viewpoint of the viscosity of a dispersion, and handleability.

  The metal thin film precursor particles used in the present invention are not limited as long as the metal thin film is formed by heat treatment, and preferably include metal particles, metal hydroxide particles, and metal oxide particles.

  As the metal particles, metal fine particles having a primary particle diameter of 10 nm or less formed by a method such as a wet method or a gas evaporation method are preferable, and copper fine particles are particularly preferable.

  Examples of the metal hydroxide particles include particles made of a compound such as copper hydroxide, nickel hydroxide, and cobalt hydroxide, but copper hydroxide particles are particularly preferable as the metal hydroxide particles that give a copper thin film.

  Metal oxide particles are particularly preferred because of the ease of forming a metal thin film by heat treatment. Examples of the metal oxide particles include copper oxide particles, silver oxide particles, palladium oxide particles, nickel oxide particles and the like. Moreover, you may use the copper oxide particle which can give copper by heat processing, As such a copper oxide particle, oxidation with a cuprous oxide particle, a cupric oxide particle, other oxidation numbers Any of the copper particles can be used. Cuprous oxide particles are particularly preferred because they can be easily reduced.

  These metal oxide fine particles may be commercially available products or may be synthesized using a known synthesis method. For example, as a method for synthesizing cuprous oxide ultrafine particles having a particle diameter of less than 100 nm, a method in which an acetylacetonato copper complex is synthesized by heating at about 200 ° C. in a polyol solvent is known (Angevante Chemi International Edition, 40, volume 2, p.359, 2001).

  Next, the polyether compound contained in the composite layer of the laminate according to the present invention will be described. The polyether compound is a compound containing a plurality of ether bonds in the molecular skeleton. In the present invention, the polyether compound is easily burned down when the composite layer is heat-treated, and the resistance value of the metal thin film obtained when burned down can be reduced. In addition, the laminate according to the present invention can suppress the cohesive failure of the composite layer because the polyether compound appropriately expresses the adhesion force to the protective film of the composite layer by containing the polyether compound, Generation of pinholes and cracks can be suppressed.

  The content ratio of the polyether compound to the metal thin film precursor in the composite layer is preferably in the range of 0.05 to 0.30 by weight. When the content ratio of the polyether compound is in the range of 0.05 to 0.30, the adhesion of the composite layer to the protective film becomes appropriate, and the film quality of the metal thin film obtained by the heat treatment is improved and the resistance is increased. The value tends to be low. When the content ratio of the polyether compound is 0.05 or more, excessive drying can be prevented during the heat treatment, and the generation of defects such as pinholes and cracks in the resulting metal thin film can also be suppressed. Moreover, when the content rate of a polyether compound is 0.30 or less, an excess polyether compound can be burned down at the time of heat processing, and the resistance value of the metal thin film obtained can be reduced. As described above, it is contradictory to suppress defects of the obtained metal thin film and to achieve a low resistance value, and in order to achieve both of them, the content ratio of the polyether compound is within the above range. Is preferred.

  As the polyether compound, a linear aliphatic polyether compound is particularly preferable. The linear aliphatic polyether compound is preferable because the resistance of the metal thin film obtained by heat treatment is particularly reduced in addition to good dispersibility with the metal thin film precursor in the composite layer.

  The number average molecular weight of the linear aliphatic polyether compound is preferably in the range of 150 to 600, and more preferably in the range of 200 to 450. When the number average molecular weight is within this range, the film forming property of the metal thin film is extremely high, and the volume resistivity of the obtained metal thin film tends to decrease because it easily decomposes and burns out. If the number average molecular weight is 150 or more, the film formability when firing to obtain a metal thin film is improved, and if the number average molecular weight is 600 or less, the volume resistivity of the resulting metal thin film can be reduced.

  The linear aliphatic polyether compound is preferably an alkylene group having 2 to 6 carbon atoms as a repeating unit. It may be a linear aliphatic polyether compound, a binary or higher polyether copolymer or a polyether block copolymer.

  Examples of the linear aliphatic polyether compound include, in addition to polyether homopolymers such as polyethylene glycol, polypropylene glycol, and polybutylene glycol, ethylene glycol / propylene glycol, ethylene glycol / butylene glycol binary copolymers, ethylene Examples include, but are not limited to, linear ternary copolymers such as glycol / propylene glycol / ethylene glycol, propylene glycol / ethylene glycol / propylene glycol, and ethylene glycol / butylene glycol / ethylene glycol. As block copolymers, binary block copolymers such as polyethylene glycol polypropylene glycol and polyethylene glycol polybutylene glycol, and linear chains such as polyethylene glycol polypropylene glycol polyethylene glycol, polypropylene glycol polyethylene glycol polypropylene glycol, polyethylene glycol polybutylene glycol polyethylene glycol, etc. And polyether block copolymers such as ternary block copolymers.

  The terminal structure of the linear aliphatic polyether compound is not limited as long as it does not adversely affect the dispersibility of the metal thin film precursor in the composite layer. In addition, when at least one terminal of the linear aliphatic polyether compound is an alkyl group, the decomposition and burnout of the polyether compound during firing is improved, and the volume resistivity of the resulting metal thin film is reduced. preferable. When the length of the alkyl group is too long, the dispersibility of the particles tends to be inhibited to increase the viscosity of the dispersion, and therefore the length of the alkyl group is preferably 1 to 4 carbon atoms. The reason why the decomposition / burning property at the time of firing is improved by having at least one terminal is an alkyl group is not clear, but hydrogen bonding between particles and a polyether compound, or between a polyether compound and a polyether compound, etc. It is surmised that the weakening of the interaction force based on this contributes.

  The linear aliphatic polyether compound has a structure in which one terminal is an alkyl group and the other terminal is a hydroxyl group. Examples of such a structure include polyethylene glycol methyl ether and polypropylene glycol methyl ether.

  There is no restriction | limiting in particular in the thickness of a composite layer, Usually, it selects and uses suitably in the range of 0.1 micrometer-100 micrometers.

  There is no restriction | limiting in particular as a protective film, For example, raw materials, such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), a polyimide, polyamide, can be used. Moreover, there is no restriction | limiting in particular in the thickness of a protective film, For example, a protective film about 1 micrometer-100 micrometers can be used.

  The surface of the protective film in contact with the composite layer is preferably treated with a peelable compound. Although there is no restriction | limiting in particular in the kind of peelable compound, A silicone compound is especially preferable. Although the action mechanism of the silicone compound is not clear, it seems that the silicone compound has an effect of weakening the chemical bond between the polyether compound and the protective film surface.

  The laminated body which concerns on this invention can obtain a metal thin film by heat-processing, after peeling a protective film. Here, although there is no restriction | limiting in the thickness of a metal thin film, Usually, it exists in the range of 0.01 micrometer-50 micrometers.

  As long as the metal thin film precursor is reduced to metal, the heat treatment is not limited in the treatment temperature, and is usually performed at a temperature of 100 ° C to 400 ° C. When the composite layer is heat-treated in contact with the thermoplastic resin layer to enhance the adhesion between the metal thin film layer and the thermoplastic resin layer, the heating temperature is higher than the glass transition temperature of the thermoplastic resin. It is preferable to heat-process with. For example, when a thermoplastic polyimide having a glass transition temperature of 260 ° C. is used for the insulating resin layer, heat treatment is preferably performed at 300 ° C. to 360 ° C., which is higher than the glass transition temperature.

  When the metal thin film layer obtained by the heat treatment is a metal species that is susceptible to oxidation, such as copper, the heat treatment is preferably performed in a non-oxidizing atmosphere. In order to reduce the resistance value of the metal thin film, heat treatment may be performed in a non-oxidizing atmosphere slightly containing an oxidant. For example, heat treatment may be performed in an inert atmosphere in which oxygen is adjusted to about 30 ppm to 500 ppm. It can be illustrated. The inert atmosphere refers to an atmosphere of an inert gas such as argon or nitrogen. For these heat treatments, a heating means such as a far-infrared ray, infrared ray, microwave, electron beam or other radiation heating furnace, or an electric furnace or oven is used.

  The laminate according to the present invention can be used as a metal bonding material for bonding copper and copper as follows. First, one of the protective films in contact with the composite layer is peeled off and overlapped downward on the copper coating surface. Next, the other protective film (on the upper surface) is peeled off, and another copper coating surface is overlaid thereon, followed by heat treatment. In the heat treatment, the heat treatment can be performed while applying pressure.

  The laminate according to the present invention can be formed by applying and drying a dispersion containing a metal thin film precursor and a polyether compound on a protective film. In addition, the laminate according to the present invention can be formed by applying and drying on another substrate and then laminating with a protective film.

  The dispersion preferably contains a metal thin film precursor and a polyether compound, and further contains a compound such as a dispersing agent as necessary in order to improve the coatability. The amount of the metal thin film precursor and the polyether compound in the dispersion is such that the polyether compound relative to the metal thin film precursor in the composite layer after the drying treatment is in the range of 0.05 to 0.30 by weight. It adjusts suitably so that it may become a content ratio. When using metal thin film precursor particles, the proportion of the metal thin film precursor particles in the dispersion is preferably 5% by weight to 90% by weight, more preferably 15% by weight to 80% by weight with respect to the total amount of the dispersion. More preferably, it is 15 to 35% by weight, and particularly preferably 20 to 35% by weight. When the weight of the particles in the dispersion is within these ranges, the dispersion state of the particles is good, and a metal thin film having an appropriate thickness can be obtained by a single coating / heating treatment.

  Polyhydric alcohol is preferable because it improves the dispersibility of the metal thin film precursor and improves the coating property. The content ratio of the polyhydric alcohol is preferably 5% by weight to 70% by weight, more preferably 10% by weight to 60% by weight, and still more preferably 40% by weight to 60% by weight with respect to the total amount of the dispersion.

  If necessary, additives such as an antifoaming agent, a leveling agent, a viscosity modifier, and a stabilizer may be added to the dispersion. The dispersion may contain the same or different metal powder as the metal species generated from the metal thin film precursor particles as long as the formation of the metal thin film by the fusion of the metal thin film precursor particles is not hindered. In order to form an interface form having high adhesive strength with the insulating resin layer, the particle size of the metal powder is preferably small. The particle size of the metal powder is more preferably 1 μm or less, further preferably 200 nm or less, and particularly preferably 50 nm or less.

  The dispersion can be applied to a substrate different from the protective film, dried, and pasted with the protective film. The substrate used can be either an organic material or an inorganic material, but heat treatment is performed when forming the metal thin film. Therefore, heat resistant ones are preferable. For example, inorganic materials such as ceramics, glass and metal, and heat resistant resins such as polyimide films are preferably used. Examples of the polyimide film include Kapton (registered trademark, manufactured by Toray DuPont), Apical (registered trademark, manufactured by Kaneka Chemical), Upilex (registered trademark, manufactured by Ube Industries), and the like. The film thickness of these substrates is not particularly limited, but is usually in the range of thicker than 1 μm and thinner than 1 mm.

  In the present invention, such a substrate may be used as it is, and in order to improve the adhesion to the metal thin film, degreasing treatment, chemical treatment with acid or alkali, heat treatment, plasma treatment, corona discharge treatment, sandblast treatment, etc. You may use it with the surface treatment. Moreover, in order to improve adhesiveness with a metal thin film, you may use it, forming adhesive layers, such as a thermoplastic resin layer, on a board | substrate. Examples of the adhesive layer include an insulating resin layer having an imide bond and / or an amide bond whose elastic modulus changes by heat treatment, such as a partially cured polyimide resin layer, in addition to a thermoplastic resin such as thermoplastic polyimide. The thickness of these adhesive layers is preferably in the range of 0.1 μm to 20 μm, more preferably 0.1 μm to 10 μm. When the film thickness is greater than 0.1 μm, film formation is facilitated, and the adhesive strength between the insulating substrate and the metal thin film layer can be sufficiently improved. Even if the film thickness exceeds 20 μm, the effect of the present invention is not hindered, but the film thickness of the substrate becomes unnecessarily thick and is often not economical.

  Examples of a method for applying a dispersion or solution containing a metal thin film precursor and a polyether compound include dip coating, spray coating, spin coating, bar coating, roll coating, ink jet, and contact printing. And a screen printing method. For these methods, an optimum coating method may be appropriately selected according to the viscosity of the dispersion. It is possible to adjust the thickness of the metal thin film finally obtained by adjusting the thickness of the dispersion to be applied.

  When the applied dispersion is dried, a readily volatile substance such as a dispersion medium is volatilized at a temperature lower than the temperature at which the metal thin film precursor becomes a metal thin film, but the drying method is not particularly limited. The drying temperature can be appropriately determined in consideration of the volatilization temperature of the composition constituting the dispersion, and is usually performed in a temperature range of 50 ° C to 200 ° C. When the organic solvent is volatilized, an explosion-proof oven or the like may be used.

(Example)
Below, the Example and comparative example which were performed in order to clarify the effect of this invention are shown. The present invention is not limited by these examples. The measuring method of the particle diameter of the metal oxide fine particles, the volume resistivity of the metal thin film, and the adhesion strength is as follows.

(1) Particle diameter of metal oxide fine particles One drop of a dispersed / diluted particle dispersion is deposited on a carbon-deposited copper mesh, and a sample dried under reduced pressure is prepared. Observe the sample using a transmission electron microscope (JEM-4000FX, manufactured by Hitachi, Ltd.), and select three locations where the particle size is relatively uniform from the field of view. Shoot at a suitable magnification. Select the three most likely particles from each photograph, measure the diameter with a ruler, and calculate the primary particle size by multiplying the magnification. The average value of the calculated primary particle sizes was taken as the particle size.

(2) Volume resistivity of metal thin film It measured using the low resistivity meter "Loresta (trademark)" GP (made by Mitsubishi Chemical Corporation).

(3) Adhesion strength measurement (180 degree peel test)
Cut the laminate with a cutter knife and a width of 3 mm and a length of 50 mm. One side of the 3 mm width side of the protective film is slightly peeled off and an aluminum tape is applied, this tape part is fixed to a peeling tester, and the force required to peel it off in the 180 ° direction is measured to measure the adhesion strength / M).

[Example 1]
(Preparation of metal thin film precursor fine particles and dispersion)
70 ml of purified water was added to 8 g of anhydrous copper acetate (manufactured by Wako Pure Chemical Industries, Ltd.). While stirring at 25 ° C., 2.6 ml of hydrazine hydrate of 64% by weight was added and reacted so that the molar ratio of hydrazine to copper acetate was 1.2, and cuprous oxide fine particles having an average primary particle size of 20 nm were reacted. Got. 2 g of polyethylene glycol methyl ether (number average molecular weight 400, manufactured by Aldrich) and 7 g of diethylene glycol were added to 3 g of the obtained cuprous oxide, and ultrasonic dispersion was performed to obtain a cuprous oxide dispersion.

(Create laminate)
A polyimide film cut out to the same size on a 10 cm square glass substrate (Kapton film manufactured by Toray DuPont, film thickness 50 μm) was bonded with a double-sided tape, and then set on a spin coater (1H-D7 type) manufactured by Mikasa. . On this polyimide film, 2 ml of the above-mentioned cuprous oxide dispersion was dropped, and then applied by spin coating under conditions of 500 rpm × 15 seconds. Next, this coating film was put in an oven and dried under conditions of 150 ° C. × 10 minutes, and then the surface was overlaid with a silicone-treated PET film and pressed with 1 kgf to obtain a laminate.

(Measurement of adhesion strength and analysis of composite layer)
The adhesion strength of the protective film according to the 180 degree peel test was 0.1 kN / m. The weight ratio of polyethylene glycol methyl ether to cuprous oxide contained in the composite layer was 0.2. The protective film was peeled off, and the copper thin film obtained by heat treatment in a hydrogen atmosphere at 350 ° C. for 10 minutes had a copper thickness of 0.5 μm and a volume resistance value of 1.8 μΩcm.

[Examples 2 to 4]
Laminates were obtained by varying the drying conditions and evaluated in the same manner as in Example 1. The results of Examples 1 to 4 are shown in Table 1 below. In Table 1 below, regarding the copper thin film film quality, the copper film after the heat treatment was judged as “good” when there were few pinholes and cracks were not generated, and the other was judged as “bad”. In addition, pinholes and cracks are observed in a transmission light mode of an optical microscope for a laminate obtained by heat treatment, round holes of 100 μm or more are pinholes, cracks having a length of 300 μm or more Were classified as cracks.

[Example 5]
To 3 g of cuprous oxide obtained in Example 1, 4 g of polyethylene glycol methyl ether (number average molecular weight 250, manufactured by Aldrich) and 7 g of diethylene glycol were added, and ultrasonic dispersion was performed to obtain a cuprous oxide dispersion. Obtained. Table 1 below shows the results obtained by obtaining a laminate by the same method as in Example 1 except that the drying conditions are changed to 120 ° C. × 10 minutes.

  As shown in Table 1, since the adhesion strength was 0.2 kN / m or less, the resistance values were all low (Examples 1 to 5).

[Comparative Example 1]
A laminate was obtained in the same manner as in Example 1 except that the drying conditions were 130 ° C. × 10 minutes. The weight ratio was 0.35, and the adhesion strength was 0.23 kN / m. In the process of peeling the protective film, the composite layer was subjected to cohesive failure, and many pinholes were confirmed in the copper film obtained by heat treatment. Also, the resistance value was as high as 3.3 μΩcm. The cohesive failure was determined by confirming that a part of the composite layer was adhered to the protective film as a lump by microscopic observation of the peeled protective film.

[Comparative Example 2]
A laminate was obtained in the same manner as in Example 1 except that a PET film not subjected to silicone treatment was used. The adhesion strength was 0.29 kN / m. In the process of peeling the protective film, the composite layer was subjected to cohesive failure, and many pinholes were confirmed in the copper film obtained by heat treatment.

  As shown in Table 2, when the adhesion strength was 0.23 kN / m and 0.29 kN / m, the resistance value increased (Comparative Example 1 and Comparative Example 2).

  As described above, the laminate according to the present invention can form a metal thin film having few pinholes and having a very low resistance value equivalent to that of a bulk metal by heat treatment after peeling off the protective film. In addition, after the dispersion is coated on a substrate and dried, the obtained dried film can be once pasted with a protective film and stored. Furthermore, since it can progress to a heat processing process, confirming conditions, it is easy to cope with the malfunction of a heat processing process, and the resistance value of the metal thin film obtained can be adjusted with high precision. Further, the thickness of the metal film can be arbitrarily controlled, and a thin metal film can be easily formed.

  Since the laminated body according to the present invention can form a metal thin film having few pinholes and a very low resistance value comparable to that of a bulk metal, it can be particularly suitably used as a flexible wiring board material or a bonding material.

Claims (11)

  A composite layer containing a metal thin film precursor and a polyether compound, and a protective film laminated on at least one surface of the composite layer, and an adhesion strength between the composite layer and the protective film is 0.2 kN / M or less, The laminated body characterized by the above-mentioned.   The laminate according to claim 1, wherein a content ratio of the polyether compound to the metal thin film precursor in the composite layer is in a range of 0.05 to 0.30 by weight.   3. The metal thin film precursor is at least one metal thin film precursor particle selected from the group consisting of metal particles, metal oxide particles, and metal hydroxide particles. The laminated body of description.   The laminate according to claim 3, wherein a primary particle diameter of the metal thin film precursor particles is 200 nm or less.   The laminate according to claim 3 or 4, wherein the metal thin film precursor particles are cuprous oxide particles.   The laminate according to any one of claims 1 to 5, wherein the protective film has a surface that is in contact with the composite layer and surface-treated with a peelable compound.   The laminate according to claim 6, wherein the peelable compound is a silicone compound.   The laminate according to any one of claims 1 to 7, wherein the polyether compound is a linear aliphatic polyether compound.   The laminate according to claim 8, wherein the linear aliphatic polyether compound has a molecular weight of 150 to 600 and an alkyl group at one end.   The metal thin film obtained by heat-processing, after peeling a protective film from the laminated body in any one of Claims 1-9.   A metal bonding material obtained by peeling a protective film from the laminate according to any one of claims 1 to 9 and then heat-treating the metal film between sandwiched surfaces.