JP2011104815A - Laminate and method for producing laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate which has high adhesion between a thin metal film and a substrate and is improved in thermal deterioration with passage of time in adhesive strength and a method for producing the laminate. <P>SOLUTION: The laminate 10 includes the insulating substrate 11, an insulating resin layer 12 formed on the insulating substrate 11, and a thin metal film layer 13 which is formed on the insulating resin layer 12 and includes a metal oxide 14 on a contact interface with at least the insulating substrate 11. The insulating resin layer 12 includes a thermoplastic polyimide containing a diamine component having a biphenyl skeleton. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laminate suitably used for an electric wiring circuit board such as a printed wiring board and a method for manufacturing the same.

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

  In the plating method, a metal thin film can be formed relatively easily on a conductive base material. However, when forming a metal thin film on an insulating substrate, it is necessary to form a conductive layer first, and thus there is a problem that the process becomes complicated. In addition, since the plating method uses a reaction in a solution, 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, and the adhesion of the resulting metal thin film to the substrate Is not enough.

In a vapor phase method such as a vacuum deposition method, a sputtering method, and a CVD method, surface treatment such as plasma treatment is usually performed on the surface of the substrate before forming the metal thin film, but the substrate may be damaged by this surface treatment. For example, it is disclosed that when a polyimide film is subjected to plasma treatment, an imide ring of a surface layer is cleaved, and oxygen functional groups and nitrogen functional groups are generated depending on a difference 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 kN due to the interaction between the nitrogen functional group and copper by vapor deposition of copper. It is disclosed that a laminate of about / m can be obtained. However, the presence of a nitrogen functional group generated by modification of polyimide has a concern that film physical properties are lowered 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 metal paste method does not require a special apparatus such as a vacuum apparatus and has an advantage that the process is simple. However, in order to melt the metal filler, a high temperature of 1000 ° C. or higher is usually required. For this reason, as a base material, it is restricted to what has heat resistance, such as a ceramic base material. Moreover, there is a concern that the base material is damaged by heat, or that 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.

  In Patent Document 2, a mixture composed of a metal powder and a reactive organic medium is applied onto a coating layer that is a diffusion and adhesion barrier such as a soluble polyimide, and heat treatment is performed, whereby adhesion to a substrate is improved. It is disclosed. Specifically, when forming a copper film from a mixture of copper powder and a copper-based reactive organic medium, a protective atmosphere (a nitrogen atmosphere with an oxygen concentration of less than 3 ppm or a reducing atmosphere containing hydrogen) is used to prevent copper oxidation. Heat treatment in the inside is preferable, and in that case, it is exemplified that the fixing property to the extent that the tape test is cleared can be obtained. However, the adhesive strength of the laminate disclosed in Patent Document 2 is about 1 kN / m, 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 forming a metal thin film directly on an insulating substrate using a dispersion in which metal fine particles having a particle size 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. Further, the method for producing metal particles of 100 nm or less used here is a method for rapidly cooling metal vapor volatilized in a low-pressure atmosphere, so that mass production is difficult, and therefore 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 for 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. Yes. 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, in order to decompose the crystalline polymer, 400 ° C. to A high temperature of 900 ° C. is required. For this reason, the base material which can be used needs the heat resistance more than the temperature, and there exists a problem in which the kind of base material which can be used is restrict | limited. 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 method, 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, etc., and to use it as a material for flexible printed wiring boards. Is possible. However, the adhesion strength may decrease to about 0.4 kN / m or less due to thermal degradation with time, and further improvement in the thermal degradation characteristics of the adhesion strength with time is required as the wiring becomes finer.

JP 2005-54259 A Special table 2003-506882 gazette Japanese Patent No. 2561537 Japanese Patent Laid-Open No. 5-98195 WO03 / 051562 pamphlet

  This invention is made | formed in view of this point, and it aims at providing the laminated body with which the adhesiveness of a metal thin film and a board | substrate is high, and the time-dependent heat deterioration of adhesive strength was improved, and its manufacturing method. .

  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 is formed on an insulating substrate, an insulating resin layer formed on the insulating substrate, and the insulating resin layer, and contains a metal oxide at least at a contact interface with the insulating substrate. A metal thin film layer, wherein the insulating resin layer includes a thermoplastic polyimide containing a diamine component having a biphenyl skeleton.

  In the laminate of the present invention, the thermoplastic polyimide preferably has a glass transition temperature of more than 270 ° C. and 350 ° C. or less.

  In the laminate of the present invention, the thermoplastic polyimide preferably has a water absorption of 1% or less.

  In the laminate of the present invention, the diamine component is preferably 4,4'-bis (3-aminophenoxy) biphenyl or 4,4'-bis (4-aminophenoxy) biphenyl.

  In the laminated body of this invention, it is preferable that the said metal thin film layer contains copper.

  In the laminate of the present invention, the metal oxide present at the contact interface between the insulating resin layer and the metal thin film layer contains at least one selected from cuprous oxide, nickel oxide, and cobalt oxide. Is preferred.

  The method for producing a laminate of the present invention includes a step (1) of forming an insulating resin layer on an insulating substrate, a step (2) of forming a metal thin film layer on the insulating resin layer, and the insulating property. And (3) forming a metal oxide at a contact interface between the resin layer and the metal thin film layer.

  In the manufacturing method of the laminated body of this invention, it is preferable to implement both the said process (2) and the said process (3), or to implement a process (3) after implementing a process (2).

  In the method for producing a laminate of the present invention, the metal thin film layer is formed by heat-treating at least one metal thin film precursor selected from the group consisting of metal fine particles, metal oxide fine particles, and metal hydroxide fine particles. It is preferable to do.

  In the manufacturing method of the laminated body of this invention, it is preferable that the said metal thin film precursor is a cuprous oxide fine particle.

  The laminate of the present invention is manufactured by the above-described laminate manufacturing method.

  The printed wiring board of the present invention is produced using the above laminate.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesiveness of a metal thin film and a board | substrate is high, and the laminated body with which the time-dependent thermal deterioration of adhesive strength was improved, and its manufacturing method can be provided.

It is a cross-sectional schematic diagram of the laminated body which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of a laminate 10 according to the present embodiment. As shown in FIG. 1, a laminate 10 according to the present embodiment is provided on an insulating substrate 11, an insulating resin layer 12 provided on the insulating substrate 11, and the insulating resin layer 12. A metal thin film layer 13. A metal oxide 14 is present at the contact interface between the insulating resin layer 12 and the metal thin film layer 13, and the insulating resin layer 12 is a thermoplastic polyimide containing a diamine component having a biphenyl skeleton.

  The insulating substrate 11 used in the laminate 10 according to the present embodiment may be either an organic material or an inorganic material, but is preferably heat-resistant because heat treatment is performed when the metal thin film is formed. For example, inorganic materials such as ceramics and glass, and heat resistant resins such as polyimide films are preferably used.

  In the present embodiment, the thermosetting polyimide film that is particularly preferably used as the insulating substrate 11 is formed by condensing pyromellitic acid or a pyromellitic acid derivative and an aromatic diamine, such as Kapton (registered). A product obtained by condensing biphenyltetracarboxylic acid or a biphenyltetracarboxylic acid derivative and an aromatic diamine, such as UPILEX (registered trademark, registered trademark, Ube Industries, Ltd.). Although the film thickness of a polyimide film is not limited, Usually, about 9 micrometers-100 micrometers can be suitably selected and used according to a use.

  In the present embodiment, such an insulating substrate 11 may be used as it is, but in order to improve the adhesion with the insulating resin layer formed thereon, degreasing treatment, chemical treatment with acid or alkali, Surface treatment such as heat treatment, plasma treatment, corona discharge treatment, and sandblast treatment may be performed.

  In the present embodiment, an insulating resin layer 12 is formed on the insulating substrate 11, and a metal thin film layer 13 is further laminated thereon. The insulating resin layer 12 is a thermoplastic polyimide containing a diamine component having a biphenyl skeleton. By having the biphenyl skeleton, the insulating resin layer 12 exhibits an adhesive strength between the insulating resin layer 12 and the metal thin film layer 13, and the heat deterioration with time of the adhesive strength is improved.

  Furthermore, in this embodiment, 4,4′-bis (3-aminophenoxy) biphenyl or 4,4′-bis (3-aminophenoxy) biphenyl or 4,4′-bis (3-aminophenoxy) biphenyl is used as the diamine component having the biphenyl skeleton from the viewpoint of further improving the adhesive strength and suppressing thermal deterioration of the adhesive strength with time. It is preferable to use 4′-bis (4-aminophenoxy) biphenyl.

The thermoplastic polyimide preferably has an insulating property that is usually used as an insulating film for electric wiring, and preferably has an insulating property with a volume resistivity of 10 ¹³ Ωcm or more.

  Thermoplastic polyimides have a tendency that the modulus of elasticity is greatly reduced by heating above the glass transition temperature. The glass transition temperature of the thermoplastic polyimide resin is preferably more than 270 ° C. and not more than 350 ° C., more preferably more than 270 ° C. and not more than 300 ° C., from the viewpoint of the hardness of the polyimide resin and the adhesion between the metal thin film and the insulating substrate. . When the glass transition temperature is higher than 270 ° C., the amount of deformation of the insulating resin layer 12 is reduced when a metal oxide is formed at the interface between the insulating resin layer 12 and the metal thin film layer 13 by heat treatment. This is preferable because cracks in the layer 13 are suppressed.

  As thermoplastic polyimide, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride as tetracarboxylic acid component , (3,4-dicarboxyphenyl) sulfone dianhydride, (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 2,2- At least one of bis (3,4-dicarboxyphenyl) propane dianhydride and bis (3,4-dicarboxyphenyl) difluoromethane dianhydride is used, and a diamine having at least a biphenyl skeleton is used as the diamine component. . Examples of the diamine having a biphenyl skeleton include 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, 2,5-bis (4-aminophenoxy) biphenyl, and the like. Among these, 4,4′-bis (3-aminophenoxy) biphenyl or 4,4′-bis (4-aminophenoxy) biphenyl is preferably used. Furthermore, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 3,3′- Diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 3,3′-diaminodiphenylpropane, 3,3′- Diaminobenzophenone, 2,2-bis (4- (4-aminophenoxy) phenyl) perfluorophenol It may be used in conjunction pan or the like as a diamine component.

  As the thermoplastic polyimide, a thermoplastic polyimide containing a diamine component having a biphenyl skeleton alone or a mixture of at least one other thermoplastic polyimide may be used, or a resin having a different chemical composition. A plurality of layers may be laminated. When the insulating resin layer 12 has a plurality of layers made of resins having different chemical compositions, a layer made of thermoplastic polyimide containing a diamine component having a biphenyl skeleton is at least at the interface in contact with the metal thin film layer 13. Need to be deployed.

  In the laminate 10 according to the present embodiment, the thickness of the insulating resin layer 12 containing thermoplastic polyimide is 0.1 μm to 5 μm from the viewpoint of adhesion between the insulating substrate 11 and the metal thin film layer 13 and economy. preferable.

  In the present embodiment, the metal thin film layer 13 is laminated on the insulating resin layer 12. The metal species of the metal thin film layer 13 is not particularly limited as long as it can be formed on the insulating resin layer 12, and copper, silver, nickel, palladium, and the like are preferably used. Copper is particularly preferable for use as a printed wiring board.

  The surface roughness (Ra) of the contact interface between the insulating resin layer 12 and the metal thin film layer 13 is preferably larger from the viewpoint of adhesiveness. This is because when the metal particles are embedded in the insulating resin layer 12 at the contact interface, an adhesion mechanism due to the anchor effect is added, so that particularly high adhesion strength can be expressed. On the other hand, the surface roughness is preferably less than 100 nm from the viewpoint of easily forming a fine circuit. Therefore, the surface roughness is preferably 3 nm to 50 nm from the viewpoint of easily forming a fine circuit and achieving high adhesive strength.

  In the laminated body 10 which concerns on this Embodiment, although there is no restriction | limiting in the thickness of the metal thin film layer 13, Usually, they are 0.01 micrometer-50 micrometers.

When the volume resistivity of the metal thin film layer 13 is 1.6 × 10 ⁻⁶ Ωcm or more and less than 4 × 10 ⁻⁶ Ωcm, electric circuit characteristics are improved, and metal plating is performed on the metal thin film layer 13. When the layer is formed by electroplating, it is preferable because a dense plating layer can be easily formed. The volume resistivity of the metal thin film layer 13 is particularly preferably 1.6 × 10 ⁻⁶ Ωcm or more and less than 3 × 10 ⁻⁶ Ωcm.

A specific surface area estimated from small-angle X-ray scattering of the metal thin film layer 13 is preferably 0 μm ⁻¹ or more and less than 3.0 μm ⁻¹ , because the mechanical properties of the metal thin film layer 13 are improved. The specific surface area of the metal thin film layer 13 is particularly preferably 0.5 μm ⁻¹ or more and less than 2.5 μm ⁻¹ .

The estimation of the specific surface area by small angle X-ray scattering measurement can be calculated as follows. For the scattering profile obtained by making X-rays incident on the metal thin film layer 13 perpendicularly and detecting the transmitted scattered light with a detector, Document A (Roe, RJ., Methods of X-Ray and Neutron) Scattering in PolymerScience, Oxford, New York, 2000, Orthober, D., Bergmann, A., and Glatta, O., J. Appl. Cryst. 33, 218 (2000), as shown in the sky. The scattering profile I (q) from the metal thin film layer 13 having an absolute intensity can be obtained by performing absolute intensity correction and slit correction as necessary. q is the absolute value of the scattering vector represented by the following formula (1), θ is the Bragg angle, and λ is the incident X-ray wavelength.
q = 4πsin θ / λ (1)

If a two-dimensional detector is used, it is converted into a one-dimensional scattering profile by an annular average or the like. Further, the X-ray scattering is measured in a q range where the slope becomes a straight line of about −4 when I (q) is plotted logarithmically with respect to q, that is, the Porod region. Document B (Roe, RJ., Methods of X-Ray and Neutron Scattering in PolymerScience, Oxford, New York, 2000, Porod, G., Kollid-Z. 124, 83 (as shown in 51). In this Porod region, I (q) is expressed by the following formula (2) using the specific surface area S.
I (q) = 2πΔρ ² Sq ⁻⁴ Formula (2)

  In the above formula (2), S is the specific surface area, and Δρ is the difference in electron density between the component constituting the thin film and the component constituting the void (vacancy). When the void is air, the number of electrons in one cubic nanometer of the component constituting the thin film may be sufficient. As described above, the specific surface area S can be obtained by performing scattering measurement in the Porod region and fitting the absolute intensity I (q) by the above equation (2).

  In the laminate 10 according to the present embodiment, the metal oxide 14 is present at the contact interface between the metal thin film layer 13 and the insulating resin layer 12. The metal oxide 14 present at the contact interface has an effect of increasing the adhesive strength between the metal thin film layer 13 and the insulating resin layer 12, and is preferably distributed uniformly over the entire interface. The reason for the effect of increasing the adhesive strength by the metal oxide 14 is not necessarily clear, but it is considered to form a preferable chemical bond with the imide group of the thermoplastic polyimide. In addition, although the reason for the improvement effect due to thermal deterioration of adhesion strength due to the use of a thermoplastic polyimide containing a diamine component having a biphenyl skeleton is not necessarily clear, the conjugated interaction between the polymer chains of the biphenyl skeleton itself is small. This is considered to be because, for example, the low water absorption of the thermoplastic polyimide resin containing the diamine component exhibits a favorable effect on the thermal deterioration with time. When the water absorption is 1% or less, thermal deterioration with time is particularly suppressed.

  In the present embodiment, even if the insulating resin layer 12 is not subjected to imide group modification treatment by plasma treatment or the like, high adhesion strength is exhibited by the presence of the metal oxide 14. In plasma treatment, imide groups are usually converted to other nitrogen-containing polar groups by the high energy of plasma, which is said to contribute to improved adhesion, but such polar groups contribute to hygroscopicity and metal ion migration. There are concerns about adverse effects. In the present embodiment, the hygroscopicity and metal ion migration can be maintained because the adhesive strength is high without performing such treatment.

  Although there is no restriction | limiting in particular as thickness of the metal oxide 14, Usually, it is the range of 1 nm-200 nm from an adhesive strength and electroconductive viewpoint. Examples of the metal oxide 14 include copper oxide, nickel oxide, cobalt oxide, silver oxide, ruthenium oxide, osmium oxide, manganese oxide, molybdenum oxide, and chromium oxide. Among these, copper oxide, nickel oxide, and cobalt oxide are preferable from the viewpoint of improving adhesiveness, and cuprous oxide is particularly preferable.

  In the present embodiment, in the combination of the metal thin film layer 13 and the metal oxide 14, it is preferable that the metal thin film layer 13 contains copper, and the metal oxide 14 is cuprous oxide, nickel oxide, or cobalt oxide. This is a case of at least one component, and particularly preferable is a case where the metal thin film layer 13 contains copper and the metal oxide 14 is cuprous oxide.

  It is preferable to form a plated metal layer on the metal thin film layer 13 described above. The laminate 10 having a metal plating layer is preferable because the metal plating layer can add characteristics such as electrical characteristics and mechanical characteristics to the metal thin film layer 13. Although there is no restriction | limiting in particular in the metal seed | species of a metal plating layer, Copper, nickel, gold | metal | money, etc. are preferable from a viewpoint of electroconductivity or stability. Copper is particularly preferred because of its low resistance value and industrial availability. Although there is no restriction | limiting in the thickness of a metal plating layer, Usually, it is 0.05-50 micrometers.

Next, the manufacturing method of the laminated body which concerns on this Embodiment is demonstrated.
The method for manufacturing a laminate according to the present invention includes a step (1) of forming an insulating resin layer on an insulating substrate, a step (2) of forming a metal thin film layer on the insulating resin layer, and an insulating resin. And (3) forming a metal oxide at the contact interface between the layer and the metal thin film layer. The order of the steps (1) to (3) is not particularly limited, but the step (2) and the step (3) are performed simultaneously (both) or after the step (2) is performed, the step (3 ) Is preferably carried out. In addition, it is particularly preferable to perform the step (2) and the step (3) at the same time because the number of steps is small and low cost can be achieved. Hereinafter, each process (1)-process (3) is demonstrated.

  In the step (1) of forming the insulating resin layer on the insulating substrate, the method for forming the insulating resin layer is not particularly limited, and a conventionally known method can be used.

  In the step (1) of forming an insulating resin layer on an insulating substrate, the insulating resin solution is applied on the insulating substrate and dried, or the insulating resin precursor solution is applied on the insulating substrate. A method of forming an insulating resin layer by performing heat treatment and the like can be exemplified.

  For example, the insulating resin layer is formed by applying a solution such as a thermoplastic polyimide resin on an insulating substrate, and then performing a solvent removal treatment to form an insulating resin layer containing the thermoplastic polyimide resin on the insulating substrate ( A-1) and a solution of a thermoplastic polyimide resin precursor on an insulating substrate, and then a heat treatment for solvent removal and dehydration condensation reaction is performed to form an insulating resin layer containing the thermoplastic polyimide resin on the insulating substrate. And a forming method (A-2).

  In the method (A-1), the solvent is removed from the thermoplastic polyimide resin solution coated on the insulating substrate by a method such as heat treatment. At this time, it is preferable to perform the heat treatment while gradually raising the temperature from a low temperature to a high temperature. If the heat treatment is performed rapidly at a high temperature, a skin layer may be formed on the resin surface, and the solvent may be difficult to evaporate or may foam.

  According to the method (A-2), after applying the thermoplastic polyimide resin precursor solution, the solvent is removed by heat treatment, and imide ring closure is performed by dehydration condensation reaction. Regarding this heat treatment, the solvent removal treatment and the imide ring closure treatment may be performed simultaneously or sequentially. It is desirable to perform the heat treatment while gradually raising the temperature from a low temperature to a high temperature. It is also possible to use a plurality of polyimide precursors in a laminated manner. In this case, in order to provide sufficient adhesion between the polyimide resin layers in the laminate, a plurality of precursor solutions can be applied collectively or sequentially. Or after the solvent removal treatment at a temperature equal to or lower than the imide ring-closing reaction temperature, the heat conversion of the precursor to polyimide is preferably performed collectively. As a polyimide resin precursor, the compound which produces | generates a thermoplastic polyimide by heating, such as a polyamic acid (polyamic acid), a diisocyanate adduct, etc. is pointed out.

  The method of applying a solution such as a thermoplastic polyimide resin or a thermoplastic polyimide resin precursor on an insulating substrate is not limited. For example, dip coating, bar coating, spin coating, roll coating, spray coating, etc. are used. It is done. An organic solvent is usually used as the solvent used in the solution at the time of application. Examples of the organic solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, dimethylsulfone, hexamethylphosphoramide, tetramethylurea, N-methylcaprolactam, ptirolactam, tetrahydrofuran, m-dioxane, p-dioxane, 1,2-dimethoxyethane, bis (2- Methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis-2- (2-methoxyethoxy) ethyl ether, 1,3-dioxane, 1,4-dioxane, cyclohexanone, pyridine, picoline, etc. It is done. These solvents may be used alone or in combination of two or more.

  The concentration of the thermoplastic polyimide resin solution depends on the degree of polymerization of the insulating resin or the insulating resin precursor, but is usually 5% by weight to 30% by weight from the viewpoint of film thickness adjustment and the solution viscosity, preferably Is 10 wt% to 20 wt%. When the solution viscosity is high, various additives such as a smoothing agent, leveling material, and defoaming agent for imparting smoothness to the coating film surface can be added as necessary. In order to adjust the evaporation rate of the solvent, an aromatic hydrocarbon solvent can be used as long as it dissolves uniformly. Furthermore, you may add various additives and catalysts, such as hardening | curing agents, such as a well-known amine type hardening | curing agent, adhesiveness imparting agents, such as a silane coupling agent and an epoxy compound, and flexibility imparting agents, such as rubber | gum.

  In the step (2) of forming the metal thin film layer on the insulating resin layer, the method for forming the metal thin film layer is not particularly limited, and in addition to dry plating methods such as sputtering, vacuum deposition, and ion plating, Examples thereof include a wet plating method and a method in which a layer containing a metal thin film precursor is formed on an insulating resin layer and then converted into a metal thin film by heat treatment in a non-oxidizing atmosphere.

  In the method of performing a heat treatment in a non-oxidizing atmosphere after forming a layer containing a metal thin film precursor on the insulating resin layer, the non-oxidizing atmosphere is exemplified by an inert atmosphere or a reducing atmosphere. Formation of the layer containing a metal thin film precursor is performed by applying a dispersion or solution containing the metal thin film precursor and drying it as necessary. Examples of the inert atmosphere in the heat treatment include nitrogen, argon, helium, and the like. Examples of the reducing atmosphere include hydrogen, carbon monoxide, and the like. In the reducing atmosphere, an oxidizing gas up to about 1000 ppm which does not impair the reducing ability may be included.

  The metal thin film precursor refers to a compound that can form a metal thin film by post-treatment such as heat treatment. For example, metal thin film precursor fine particles having a primary particle diameter of 200 nm or less that are fused to each other by heat treatment, or reduced to metal by heat treatment. Examples thereof include metal complexes that form metal thin films.

  In order to form a relatively thick metal thin film, a dispersion of metal thin film precursor fine particles having a primary particle diameter of 200 nm or less is particularly preferable among the dispersions or solutions containing the metal thin film precursor.

  The metal thin film precursor fine particles fused to each other by heat treatment are applied to the dispersion containing the metal thin film precursor fine particles in a film form, and the metal fine particles are joined to each other by heating, and seemingly continuous. Fine particles forming a thin film formed of the metal layer.

  The metal thin film precursor fine particles have a primary particle diameter of 200 nm or less, preferably 100 nm or less, more preferably 30 nm or less, from the viewpoint that a dense metal thin film is obtained by heat treatment. 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 fine particles used in the present embodiment are not limited as long as the metal thin film is formed by heat treatment, and preferably include metal fine particles, metal hydroxide fine particles, and metal oxide fine particles.

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

  The metal oxide fine particles are particularly preferable from the viewpoint of dispersibility in a dispersion medium and ease of forming a metal thin film by heat treatment. Examples of the metal oxide fine particles include copper oxide, silver oxide, palladium oxide, nickel oxide and the like. As the copper oxide capable of providing copper by heat treatment, any of cuprous oxide, cupric oxide, and other copper oxides having an oxidation number can be used. Cuprous oxide fine particles are particularly preferred because they can be easily reduced.

  As these metal oxide fine particles, commercially available products may be used, or they 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).

  In the present embodiment, the dispersion medium used for the metal thin film precursor fine particle dispersion is not limited as long as the fine particles can be uniformly dispersed.

  It is more preferable that the dispersion contains a polyhydric alcohol and / or a linear aliphatic polyether compound, since the film-forming property is improved when a metal thin film is obtained from the metal thin film precursor fine particles by heat treatment.

  The polyhydric alcohol is a compound having a plurality of hydroxyl groups in the molecule. Polyhydric alcohols have a moderately high boiling point and are less likely to volatilize. Use of polyhydric alcohols is preferred because it is excellent in the printability of the dispersion and the film formability when forming a metal thin film. Among the polyhydric alcohols, preferred are polyhydric alcohols having 10 or less carbon atoms, and among them, low viscosity, such as ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propane. Diol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, pentanediol, hexanediol, octanediol and the like are particularly preferable. These polyhydric alcohols may be used alone or in combination.

  The reason why polyhydric alcohol improves the film-forming property when forming a metal thin film is not necessarily clear, but when the metal thin film precursor fine particles are metal oxide fine particles or metal hydroxide fine particles, the polyhydric alcohol is on the surface of the fine particles. It is considered that it has a function of protecting the particle surface by interacting with the hydroxyl group of and inhibiting aggregation between particles. Polyhydric alcohol is also preferable because it has an effect of reducing metal oxide fine particles or metal hydroxide fine particles.

  When the dispersion contains a linear aliphatic polyether compound, it is preferable because the resistance value of the metal thin film obtained by the heat treatment is reduced in addition to the effect of improving the film formability when forming the metal thin film. The reason why the linear aliphatic polyether compound improves the film formability and reduces the resistance value is that the linear aliphatic polyether compound is a metal thin film precursor during heat treatment as a readily decomposable and easily burnable binder. This is considered to prevent local granulation of fine particles.

  The preferred number average molecular weight of the linear aliphatic polyether compound is 150 to 600. When the number average molecular weight is within this range, the film formability during the formation of the metal thin film is extremely high, and on the other hand, 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 less than 150, the film formability when fired to obtain a metal thin film tends to decrease, and if the number average molecular weight exceeds 600, the volume resistivity of the resulting metal thin film tends to increase. is there.

  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 tercopolymer, and a polyether block copolymer.

  Specifically, in addition to polyethylene homopolymers such as polyethylene glycol, polypropylene glycol and polybutylene glycol, ethylene glycol / propylene glycol, ethylene glycol / butylene glycol. Binary copolymers of ethylene glycol / propylene glycol / ethylene glycol, propylene glycol / ethylene glycol / propylene glycol, ethylene glycol / butylene glycol / ethylene glycol Examples thereof include, but are not limited to, linear ternary copolymers. As block copolymers, binary block copolymers such as polyethylene glycol polypropylene glycol and polyethylene glycol polybutylene glycol, polyethylene glycol polypropylene glycol, polyethylene glycol, and polypropylene glycol are used. Examples thereof include a polyether block copolymer such as a linear ternary block copolymer such as polyethylene glycol polypropylene glycol and polyethylene glycol polybutylene glycol polyethylene glycol.

  The structure of the terminal of the linear aliphatic polyether compound is not limited as long as it does not adversely affect the dispersibility of the fine particles and the solubility in the dispersion medium, but if at least one terminal is an alkyl group, This is preferable since the decomposition and burn-out property of the polyether compound is improved and the volume resistivity of the resulting metal thin film is lowered. If the length of the alkyl group is too long, the dispersibility of the fine particles is hindered and the viscosity of the dispersion tends to increase. 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 alkyl group is not clear, but hydrogen bonding between the fine particles and the polyether compound or between the polyether compound and the polyether compound, etc. It is surmised that the weakening of the interaction force based on this contributes.

  A particularly preferable structure of the linear aliphatic polyether compound is a structure in which one terminal is an alkyl group and the other terminal is a hydroxyl group. Examples thereof include polyethylene glycol methyl ether and polypropylene glycol methyl ether.

  Although there is no restriction | limiting in the ratio of the metal thin film precursor fine particle in a dispersion, When expressed with the weight% with respect to the total amount of a dispersion, Preferably it is 5 weight%-90 weight%, More preferably, it is 20 weight%-80 weight%. When the weight of the fine particles in the dispersion is in these ranges, it is preferable because the fine particles are dispersed, and a metal thin film having an appropriate thickness can be obtained by a single coating / heating treatment.

  The ratio of the polyhydric alcohol in the dispersion is wt% with respect to the total amount of the dispersion, preferably 5 wt% to 70 wt%, more preferably 10 wt% to 50 wt%.

  The proportion of the linear aliphatic polyether compound in the dispersion is weight% with respect to the total amount of the dispersion, preferably 0.1% to 70% by weight, more preferably 1% to 50% by weight. When the added amount of the polyether compound is less than 0.1% by weight, the denseness of the resulting metal thin film may be lowered, or the adhesion to the substrate may be lowered. When the added amount of the tellurium compound exceeds 70% by weight, the viscosity of the dispersion may increase.

  The preferred weight ratio of the polyether compound to the metal thin film precursor fine particles varies depending on the kind of fine particles used and the kind of the polyether compound, but is usually in the range of 0.01 to 10. Within this range, the denseness of the resulting metal thin film is improved, and the volume resistivity is further reduced.

  In this Embodiment, you may add additives, such as an antifoamer, a leveling agent, a viscosity modifier, and a stabilizer, to the said dispersion as needed.

  For the production of the dispersion, a general method for dispersing powder in a liquid can be used. For example, after mixing constituent raw materials such as metal thin film precursor fine particles, a dispersion medium, and a linear aliphatic polyether compound, dispersion may be performed by an ultrasonic method, a mixer method, a three-roll method, or a ball mill method. Of these dispersing means, a plurality of dispersing means can be combined for dispersion. These dispersion treatments may be performed at room temperature, or may be performed by heating in order to reduce the viscosity of the dispersion. When the constituents other than the metal thin film precursor fine particles are solid, it is preferable to perform the above operation by adding the fine particles while heating them to a liquid temperature. When the dispersion becomes a flowable solid, the dispersion is preferably performed while applying a shear stress, and a three-roll method, a mixer method, and the like are preferable.

  Examples of the method for applying the dispersion or solution of the metal thin film precursor include a dip coating method, a spray coating method, a spin coating method, a bar coating method, a roll coating method, an ink jet method, a contact printing method, and a screen printing method. It is done. What is necessary is just to select the optimal application | coating method suitably according to the viscosity of a dispersion. By adjusting the film thickness of the dispersion to be applied, it is possible to adjust the film thickness of the finally obtained metal thin film.

  The applied dispersion or solution is preferable because a dense metal thin film layer may be formed by performing a drying step before heat treatment. The drying process refers to the operation of volatilizing a readily volatile substance such as a dispersion medium at a temperature lower than the temperature at which the metal thin film precursor is converted to a metal thin film. The temperature takes into account the volatilization temperature of the composition constituting the dispersion. However, it is usually performed in a temperature range of 50 ° C to 200 ° C.

  A metal circuit pattern can be formed by applying a dispersion or solution of a metal wiring formation precursor to a circuit shape and heat-treating it. When these solutions are applied, for example, a drop-on-demand type application device such as an ink jet printer or a dispenser is used.

  In the ink jet method, a dispersion or solution is placed in an ink jet printer head, and droplets containing a metal thin film precursor are ejected by applying micro vibrations to a piezoelectric element or the like by electric drive. In the dispenser method, a dispersion containing a metal thin film precursor is ejected by putting the dispersion into a dispenser tube having a discharge needle at the tip and applying air pressure.

  The circuit pattern can be formed by moving an inkjet head or a dispenser discharge needle in a plane direction by a robot. In these coating methods, it is possible to form a circuit that follows a step by moving the robot in the vertical direction even on a substrate having a step.

  In the ink jet method, the line width of a wiring pattern to be drawn can be adjusted by controlling the size of a droplet discharged from an ink jet printer head and its landing pattern. In the dispenser method, it is possible to adjust the line width of the wiring pattern to be drawn by controlling the width of the liquid droplets discharged from the discharge needle by the inner and outer diameters of the discharge needle, the discharge pressure, the drawing speed, etc. It is.

  In the application applied to the circuit shape, the line width of the dispersion or solution to be applied is usually in the range of 1 μm to 400 μm, and the line width of the obtained metal wiring is 0.5 μm to 300 μm. Moreover, it is possible to adjust the thickness of the metal wiring finally obtained by adjusting the thickness to apply. Usually, the thickness of the dispersion to apply | coat is 0.1 micrometer-100 micrometers, and the thickness of the metal wiring obtained is 0.05 micrometer-50 micrometers.

  In the step (3) of forming the metal oxide on the insulating resin layer, the method of forming the metal oxide is preferably a method in which heat treatment is performed in an inert atmosphere containing an oxidizing agent. The oxidizing agent is not particularly limited as long as a metal oxide can be formed at the interface between the insulating resin layer and the metal thin film layer, and examples thereof include oxygen, ozone, and water. The concentration of the oxidizing agent in the atmosphere may be appropriately determined in consideration of the ease of oxidation of the metal thin film layer.

  The heat treatment is preferably performed at a temperature equal to or higher than the glass transition temperature of the thermoplastic insulating resin, more preferably 5 ° C to 100 ° C higher than the glass transition temperature, for example, a thermoplastic polyimide resin having a glass transition temperature of 275 ° C. When used, heat treatment is performed at 280 ° C. to 375 ° 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, it is preferable to perform the heat treatment in a non-oxidizing atmosphere containing an oxidizing agent, particularly preferably oxygen is 20 ppm to Heat treatment in an inert atmosphere adjusted to about 2000 ppm. The inert atmosphere refers to an atmosphere of an inert gas such as argon or nitrogen. If the oxygen concentration is less than 20 ppm, the formation of the metal oxide at the interface may have a long heat treatment. On the other hand, if the oxygen concentration exceeds 2000 ppm, the oxidation is excessive and the conductivity of the metal thin film layer is low. May decrease. The heating temperature and the heating time may be appropriately determined in accordance with the susceptibility to interface oxidation and the like, but the heating temperature is usually 200 ° C. to 500 ° C., and the heating time is usually in the range of 1 minute to 120 minutes.

  For these heat treatments, a heating means such as a radiation heating furnace such as far infrared rays, infrared rays, microwaves, and electron beams, an electric furnace, or an oven is used.

  In the manufacturing method of the laminated body according to the present embodiment, the reason why the adhesive strength of the laminated body is improved is not necessarily clear, but the insulating resin layer and the metal can be obtained by performing heat treatment at a temperature equal to or higher than Tg of the thermoplastic insulating resin. It is presumed that the adhesion interface with the thin film layer increases, and at the same time, the oxide generated at the interface also increases the chemical bond with the insulating resin layer.

  Moreover, as a method of carrying out the step (2) and the step (3) at the same time, for example, after forming a layer containing a metal thin film precursor on an insulating resin layer, heating in an inert atmosphere containing an oxidizing agent Processing can be exemplified. In this case, a process of forming a metal thin film precursor layer on the insulating resin layer is started. Next, a step (2) of forming a metal thin film layer by heat treatment under, for example, a nitrogen atmosphere condition containing oxygen and a step (3) of forming a metal oxide at the interface between the insulating resin layer and the metal thin film layer. It carries out as one process continuously. Thus, since a process (2) and a process (3) can be implemented as one process continuously, a manufacturing process of a layered product can be simplified and cost reduction can be realized.

  In the present embodiment, metal plating is performed on the metal thin film layer obtained as described above to form a metal plating layer, and functions and characteristics can be imparted to the metal thin film layer. Examples of the technique for performing metal plating on the metal thin film include a dry plating method and a wet plating method. The wet plating method is preferable from the viewpoint of the film formation rate. As the wet plating method, either an electroless plating method or an electrolytic plating method can be used, but the electrolytic plating method is preferable from the viewpoint of the deposition rate of plating and the denseness of the resulting metal film.

  There is no particular limitation on the metal species for plating, but copper, nickel, gold, and the like are preferable from the viewpoint of conductivity and stability. Copper is particularly preferred because of its low resistance value and industrial availability. The plating step is performed by degreasing the surface to be plated and / or removing the oxide layer as necessary, and then immersing the substrate in a plating reaction solution. In the case of electrolytic plating, a plated layer can be formed by energizing the surface to be plated of the substrate.

  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.

  Particle diameter of metal thin film precursor fine particles, volume resistivity of metal thin film, adhesion / adhesion strength, surface roughness (Ra) of contact interface between metal thin film layer and insulating resin layer, estimation of specific surface area of metal thin film layer and The glass transition temperature (Tg) and the water absorption rate of the thermoplastic polyimide are measured as follows.

<1> Particle Size of Metal Thin Film Precursor Fine Particles One drop of dissolved / diluted fine particle dispersion is deposited on a carbon-deposited copper mesh, and a sample dried under reduced pressure is prepared. Using a transmission electron microscope (JEM-4000FX) manufactured by Hitachi, Ltd., select three locations where the particle size is relatively uniform from the field of view, and is most suitable for measuring the particle size of the object to be measured. Shoot at a magnification. From each photograph, select the three most likely particles, measure the diameter with a ruler, and multiply the magnification to calculate the primary particle size. Let the average value of these values be a particle diameter.

<2> Volume resistivity of metal thin film Measured using a low resistivity meter “Loresta (registered trademark)” GP (manufactured by Mitsubishi Chemical Corporation).

<3> Tape peel test and adhesive strength measurement (180 degree peel test)
In the tape peeling test, a scotch tape (registered trademark, manufactured by Sumitomo 3M Co.) is applied on the obtained metal thin film, and when this is peeled off, the metal thin film adheres to the scotch tape and is judged by whether it has peeled off from the substrate .

About the sample preparation method and measuring method of adhesive strength, it carried out according to JIS C6471 standard. A sample for measuring the adhesive strength is prepared as follows. After the metal film was thickened by electroplating on the obtained metal thin film and the total thickness of the metal part was about 15 μm, it was cut into a size of 15 cm long × 1 cm wide, leaving a center width of 3 mm of 1 cm, Etched with ferric chloride solution. The obtained sample was left to dry in a dryer at 105 ° C. for 1 hour or longer, and then attached to a 3 mm thick glass epoxy substrate with a double-sided adhesive tape. A conductor having a width of 3 mm was peeled off at the interface with the polyimide film and attached to an aluminum tape to make a grip allowance.

  The sample produced as described above was fixed to a tensile tester (Autograph AG-10KNI) manufactured by Shimadzu Corporation. When fixing, a jig was attached in order to surely peel it in the direction of 180 °. The load at the time of peeling 50 mm at a speed of about 50 mm per minute was measured, and the adhesive strength (kN / m) was calculated.

  In addition, in order to evaluate the heat deterioration with time of the adhesion strength, the adhesion strength measured after the heat treatment at 128 ° C. for 240 hours was defined as the adhesion strength after the heat deterioration with time, and the above method was used for adhesion. The strength was measured.

<4> Observation of metal thin film and contact interface form between metal thin film and insulating resin layer (surface roughness Ra)
The form of a metal thin film observes the cross-sectional TEM image of a laminated body using the transmission electron microscope (JEM-4000FX) by Hitachi, Ltd. The surface roughness of the contact interface between the metal thin film layer and the insulating resin layer is observed as follows. The cross-sectional TEM image of the interface portion is digitized with a scanner, and an 8-bit grayscale image of the metal thin film interface obtained by fusing is acquired. After binarization, edge extraction is performed to obtain an interface profile image (line image) of the metal thin film. Further, the surface roughness (Ra) of the contact interface between the metal thin film layer and the insulating resin layer is estimated using the amount of displacement of the line image from the straight line connecting both ends of the image profile image to the insulating resin layer side.

<5> Estimation of specific surface area of metal thin film layer Small angle X-ray scattering was measured using a rotating cathode X-ray generator with an output of 18 kW and an imaging plate as a detector. The incident X-ray wavelength is 0.154 nm, the camera length is 980 mm, and the measurement time per sample is 30 minutes. Scattering measurement was performed by injecting X-rays from the normal direction of the film surface to one copper thin film with a Kapton film attached as a base film. In the empty cell scattering measurement, the same measurement was performed on the Kapton film as the base film. Furthermore, the transmittance | permeability measurement in the incident X-ray wavelength of the copper thin film with the Kapton film for the empty cell correction | amendment, and the Kapton film was also performed. The two-dimensional scattering pattern obtained by the imaging plate was made one-dimensional by performing circular average after performing background correction. Using these data, I (q) was obtained according to the methods of the above-mentioned documents A and B. Note that the thickness of the copper thin film necessary for the absolute intensity correction was obtained from a scanning electron micrograph of the cross section. The specific surface area was obtained by fitting to I (q) obtained in this way by the said Formula (2).

<6> Glass transition temperature (Tg) of thermoplastic polyimide
Using a thermomechanical analyzer (TMA-50) manufactured by Shimadzu Corporation, a thermal load of 5 g, a heating rate of 10 ° C./min, under a nitrogen atmosphere (flow rate of 20 ml / min), and a temperature of 50 ° C. to 450 ° C. The test piece elongation in the range was measured, and the glass transition temperature of the polyimide film (25 μm thickness) was determined from the inflection point of the obtained curve.

<7> Water Absorption Rate of Thermoplastic Polyimide For the water absorption rate, three films made only of thermoplastic polyimide were prepared, and the weight of what was dried at 150 ° C. for 30 minutes using this was immersed in distilled water for 1,24 hours. After that, the weight of the water droplets on the surface was wiped, and the water absorption rate of each of the three sheets was calculated from the following formula (3), and the average value was taken as the water absorption rate.
Water absorption (%) = (W1−W2) ÷ W1 × 100 (3)

[Example 1]
(Synthesis of thermoplastic polyimide solution)
Weighing to a ratio of 0.67 mol of 4,4′-bis (3-aminophenoxy) biphenyl, 0.33 mol of 4,4′-diaminodiphenyl ether and 1.0 mol of pyromellitic dianhydride, N -Methyl-2-pyrrolidone (NMP) was added so that the solid content concentration was 10 wt%, and the mixture was stirred and dissolved at 50 ° C. for 10 hours to obtain a polyamic acid solution which is a thermoplastic polyimide precursor. The glass transition temperature of this thermoplastic polyimide was 278 ° C. The water absorption of this thermoplastic polyimide was 0.8% by weight.

(Creation of a substrate having a thermoplastic polyimide layer)
A polyimide film cut out into a 20 × 30 cm square (Kapton film 150ENC manufactured by Toray DuPont Co., Ltd., film thickness: 38 μm) is set on a bar coater and coated with a bar coat so that the film thickness becomes 1.0 μm. Polyimide having a thermoplastic polyimide resin on the surface by heating at 90 ° C for 10 minutes, 120 ° C for 10 minutes, 150 ° C for 10 minutes, 180 ° C for 10 minutes, 250 ° C for 60 minutes, 300 ° C for 60 minutes A substrate was obtained.

(Formation of metal thin film)
After setting the polyimide substrate in a sputtering apparatus and performing reverse sputtering for surface cleaning, using copper as a target, the argon flow rate was 18 cm ³ / min, the sputtering pressure was 6.0 × 10 ⁻¹ Pa, and the sputtering power was 300 W. Sputtering was performed for 9 minutes to obtain a 0.3 μm copper thin film. The specific surface area of the copper thin film was 1.4 μm ⁻¹ .

(Heat treatment)
The substrate having the copper thin film was heat-treated at 350 ° C. for 10 minutes in a nitrogen atmosphere adjusted to an oxygen concentration of 200 ppm.

(Plating layer application, adhesive strength measurement, peeling interface analysis)
80 g of copper sulfate pentahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and 180 g of sulfuric acid were dissolved in 1 liter of purified water to prepare an electrolytic plating bath. After degreasing and pickling the copper film surface obtained above, it was immersed in a plating bath and subjected to electrolytic copper plating at a current density of 3 A / dm ² at room temperature, and the total thickness of the metal layer (copper thin film layer + A laminated substrate having a copper film formed by plating of 15 μm was completed. The adhesive strength according to the 180 degree peel test was as extremely high as 1.0 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after a heat deterioration with time was as high as 0.5 kN / m. When the copper interface and the polyimide layer were subjected to XPS analysis of the copper interface, the presence of cuprous oxide could be confirmed. The Ra at the interface was 3 nm.

[Example 2]
(Formation of metal thin film)
A polyimide substrate prepared by the same method as in Example 1 was set in a vacuum deposition apparatus, the system was evacuated, and then copper was deposited to obtain a 0.3 μm copper thin film. The volume resistivity of the copper thin film was 1.7 μΩcm.

(Heat treatment)
The substrate having the copper thin film was heat-treated at 350 ° C. for 10 minutes in a nitrogen atmosphere adjusted to an oxygen concentration of 200 ppm.

(Plating layer application, adhesion strength measurement, peeling interface analysis)
An electrolytic copper plating process was performed in the same manner as in Example 1 to complete a 15 μm laminated substrate. The adhesive strength according to the 180 degree peel test was as extremely high as 1.2 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after a heat deterioration with time was as high as 0.5 kN / m. When the copper interface and the polyimide layer were subjected to XPS analysis of the copper interface, the presence of cuprous oxide could be confirmed. The Ra at the interface was 6 nm.

[Example 3]
(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 64% by weight hydrazine hydrate was added and reacted so that the molar ratio of hydrazine to copper acetate was 1.2 to obtain cuprous oxide fine particles having a particle size of 20 nm. . 2 g of polyethylene glycol methyl ether (number average molecular weight 350, 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.

(Formation of metal thin film)
A polyimide substrate prepared in the same manner as in Example 1 was set on a bar coater, and the above-mentioned cuprous oxide dispersion was dropped, followed by coating to a film thickness of 20 μm. Next, this coating film was put in an electric furnace and baked at a temperature higher than the glass transition temperature (278 ° C.) of the polyimide film under the conditions of 100% hydrogen and 350 ° C. × 30 minutes. As a result, a substrate having a copper thin film with a film thickness of 1 μm and a volume resistivity of 2.3 × 10 ⁻⁶ Ωcm was obtained.

(Heat treatment)
The substrate having the copper thin film was heat-treated at 350 ° C. for 10 minutes in a nitrogen atmosphere adjusted to an oxygen concentration of 100 ppm.

(Plating layer application, adhesive strength measurement, peeling interface analysis)
The same electrolytic copper plating as in Example 1 was performed to complete a laminated substrate having a total metal layer thickness (copper thin film layer + copper film formed by plating) of 15 μm. The adhesive strength according to the 180 degree peel test was as extremely high as 1.5 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after heat deterioration with time was as high as 0.7 kN / m. When the copper interface and the polyimide layer were subjected to XPS analysis of the copper interface, the presence of cuprous oxide could be confirmed. When the interface morphology analysis was performed, a part of the metal thin film layer was embedded and adhered in the thermoplastic polyimide layer, the depth was 10 nm to 30 nm, and Ra was 10 nm.

(Characteristics of printed wiring board)
When a comb-shaped electrode of line / space = 20 μm / 20 μm was formed on the multilayer substrate obtained above by photolithography, it was confirmed that the linearity of the wiring was extremely high and the fine wiring formation was high. Moreover, the disconnection of the wiring considered to be caused by the pinhole was not observed. A migration test was performed on the prepared comb-shaped electrode under the conditions of a temperature of 85 ° C., a relative humidity of 85%, and an applied voltage of 50 V. Even after 1000 hours, the insulation between the wirings maintained a level of 10 ¹³ Ω and absorbed moisture. The accompanying decrease in insulation was not observed.

[Example 4]
(Formation of metal thin film)
A polyimide substrate prepared in the same manner as in Example 1 was set on a bar coater, and a cuprous oxide dispersion similar to that in Example 2 was dropped, followed by coating to a film thickness of 15 μm. Next, this coating film was put in an electric furnace and baked at a temperature higher than the glass transition temperature (278 ° C.) of the polyimide film under the condition of 100% hydrogen and 330 ° C. × 20 minutes. As a result, a substrate having a copper thin film having a film thickness of 0.7 μm and a specific surface area estimated from the X-ray scattering intensity of 1.8 μm ⁻¹ was obtained.

(Heat treatment)
The substrate having the copper thin film was heat-treated at 350 ° C. for 10 minutes in a nitrogen atmosphere adjusted to an oxygen concentration of 150 ppm.

(Plating layer application, adhesive strength measurement, peeling interface analysis)
The same electrolytic copper plating as in Example 1 was performed to complete a laminated substrate having a total metal layer thickness (copper thin film layer + copper film formed by plating) of 15 μm. The adhesive strength according to the 180 degree peel test was as extremely high as 1.5 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after heat deterioration with time was as high as 0.7 kN / m. When the copper interface and the polyimide layer were subjected to XPS analysis of the copper interface, the presence of cuprous oxide could be confirmed. The Ra at the interface was 9 nm.

  In the following Example 5 to Example 7, the heat treatment condition dependency was examined.

[Example 5]
A laminated substrate having a plating layer was formed under the same conditions as in Example 3 except that the heat treatment was performed under the conditions of an oxygen concentration of 1000 ppm and 350 ° C. × 10 minutes. The adhesive strength was 1.3 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after heat deterioration with time was as high as 0.7 kN / m. Moreover, about the peeling interface of a copper layer and a polyimide layer, when the copper interface was analyzed by XPS, presence of cuprous oxide has been confirmed.

[Example 6]
A laminated substrate having a plating layer was formed under the same conditions as in Example 3 except that the heat treatment was performed under the conditions of an oxygen concentration of 50 ppm and 350 ° C. × 10 minutes. The adhesive strength was 1.1 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after heat deterioration with time was as high as 0.6 kN / m. Moreover, about the peeling interface of a copper layer and a polyimide layer, when the copper interface was analyzed by XPS, presence of cuprous oxide has been confirmed.

[Example 7]
A laminated substrate having a plating layer was formed under the same conditions as in Example 3 except that the heat treatment was performed under the conditions of an oxygen concentration of 2000 ppm and 350 ° C. × 10 minutes. The adhesive strength was 1.0 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after a heat deterioration with time was as high as 0.5 kN / m. Moreover, about the peeling interface of a copper layer and a polyimide layer, when the copper interface was analyzed by XPS, presence of cuprous oxide has been confirmed.

  In the following Example 8 and Example 9, the example which put a drying process before a baking process was investigated.

[Example 8]
A polyimide substrate prepared in the same manner as in Example 1 was set on a bar coater, and after adding the cuprous oxide dispersion of Example 3 dropwise, it was applied to a film thickness of 20 μm. Next, after drying this coating film in an oven at 150 ° C. for 5 minutes, the dried film was put into an electric furnace, and the glass transition of the polyimide film was performed at 350 ° C. for 30 minutes under the condition of 100% hydrogen. Firing was performed at a temperature higher than the temperature (278 ° C.). As a result, a substrate having a copper thin film having a thickness of 1 μm and a volume resistivity of 2.0 × 10 ⁻⁶ Ωcm was obtained.

(Heat treatment)
The substrate having the copper thin film was heat-treated at 350 ° C. for 10 minutes in a nitrogen atmosphere adjusted to an oxygen concentration of 200 ppm.

(Plating layer application, adhesive strength measurement, peeling interface analysis)
The same electrolytic copper plating as in Example 1 was performed to complete a laminated substrate having a total metal layer thickness (copper thin film layer + copper film formed by plating) of 15 μm. The adhesive strength according to the 180 degree peel test was as extremely high as 1.3 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after heat deterioration with time was as high as 0.7 kN / m. When the copper interface and the polyimide layer were subjected to XPS analysis of the copper interface, the presence of cuprous oxide could be confirmed. The Ra at the interface was 7 nm.

[Example 9]
A polyimide substrate prepared in the same manner as in Example 1 was set on a bar coater, and after adding the cuprous oxide dispersion of Example 3 dropwise, it was applied to a film thickness of 18 μm. Next, after drying this coating film in an oven at 140 ° C. for 5 minutes, the dried film was put into an electric furnace, and the glass transition of the polyimide film was performed at 350 ° C. for 10 minutes under the condition of 100% hydrogen. Firing was performed at a temperature higher than the temperature (278 ° C.). As a result, a substrate having a copper thin film with a film thickness of 0.8 μm and a specific surface area estimated from X-ray scattering of 1.2 μm ⁻¹ was obtained.

(Heat treatment)
The substrate having the copper thin film was heat-treated at 350 ° C. for 10 minutes in a nitrogen atmosphere adjusted to an oxygen concentration of 300 ppm.

(Plating layer application, adhesive strength measurement, peeling interface analysis)
The same electrolytic copper plating as in Example 1 was performed to complete a laminated substrate having a total metal layer thickness (copper thin film layer + copper film formed by plating) of 15 μm. The adhesive strength according to the 180 degree peel test was as extremely high as 1.2 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after a heat deterioration with time was as high as 0.5 kN / m. When the copper interface and the polyimide layer were subjected to XPS analysis of the copper interface, the presence of cuprous oxide could be confirmed. The Ra at the interface was 9 nm.

[Example 10]
(Formation of metal wiring)
In Example 10, an example in which the dispersion was applied in a pattern was examined. The polyimide substrate obtained in Example 1 was vacuum-adsorbed on a table of a dispenser (manufactured by Musashi Engineering). A syringe (FN-0.50N (inner diameter 50 μm), manufactured by Musashi Engineering Co., Ltd.) is fixed to the tip of the dispersion filled in the dispenser tube, connected to the air supply tube of the dispenser, and then fixed at a predetermined position of the dispenser robot. did. While applying air pressure to the tube and pushing out the dispersion, the dispenser robot was moved to a pre-programmed wiring pattern to apply the dispersion into a circuit shape. At this time, the gap between the substrate and the tip of the syringe was adjusted to 70 μm.

Next, this coated substrate was heat-treated in a hydrogen 100% atmosphere under the same conditions as in Example 3, and then heat-treated at 350 ° C. for 10 minutes in a nitrogen atmosphere containing 100 ppm oxygen to obtain a copper wiring substrate. It was. The resistance value of the copper wiring measured by the 4-terminal method was 2.4 × 10 ⁻⁶ Ωcm. Cuprous oxide was confirmed between the copper film and the thermoplastic polyimide resin layer. Separately, the adhesive strength obtained by forming a solid film was as high as 1.2 kN / m. Moreover, the adhesive strength by the 180 degree | times peeling test after a heat deterioration with time was as high as 0.5 kN / m.

[Comparative Example 1]
A copper thin film was formed in the same manner as in Example 1 on a polyimide substrate (Toray DuPont Kapton film 150ENC, film thickness 38 μm) on which a thermoplastic polyimide film was not formed. And everything was removed.

[Comparative Example 2]
A copper thin film was formed by the same operation as in Example 1 except that the heat treatment in an oxygen atmosphere was not performed, but all of the formed copper thin film was peeled off by the tape peeling test. Elemental analysis was performed on the peeled copper thin film surface, but no copper oxide was observed.

  The laminate of the present invention has high adhesiveness between the metal thin film and the substrate, and the heat deterioration with time of the adhesive strength is improved. Therefore, the laminate is suitably used for an electric wiring circuit board such as a printed wiring board.

DESCRIPTION OF SYMBOLS 10 Laminated body 11 Insulating substrate 12 Insulating resin layer 13 Metal thin film layer 14 Metal oxide

Claims (12)

  An insulating substrate, an insulating resin layer formed on the insulating substrate, a metal thin film layer 13 formed on the insulating resin layer and containing a metal oxide 14 at least at a contact interface with the insulating substrate; And the insulating resin layer includes a thermoplastic polyimide containing a diamine component having a biphenyl skeleton.   The laminate according to claim 1, wherein the thermoplastic polyimide has a glass transition temperature of more than 270 ° C and 350 ° C or less.   The laminate according to claim 1 or 2, wherein the thermoplastic polyimide has a water absorption of 1% or less.   The diamine component is 4,4'-bis (3-aminophenoxy) biphenyl or 4,4'-bis (4-aminophenoxy) biphenyl, according to any one of claims 1 to 3. The laminated body of description.   The laminate according to any one of claims 1 to 4, wherein the metal thin film layer contains copper.   The metal oxide present at the contact interface between the insulating resin layer and the metal thin film layer includes at least one selected from cuprous oxide, nickel oxide, and cobalt oxide. The laminated body in any one of Claim 5.   Step (1) of forming an insulating resin layer on an insulating substrate, Step (2) of forming a metal thin film layer on the insulating resin layer, and contact between the insulating resin layer and the metal thin film layer And a step (3) of forming a metal oxide at the interface.   The method for manufacturing a laminate according to claim 7, wherein the step (2) and the step (3) are both performed, or the step (3) is performed after the step (2) is performed. .   8. The metal thin film layer is formed by heat-treating at least one metal thin film precursor selected from the group consisting of metal fine particles, metal oxide fine particles, and metal hydroxide fine particles. Item 9. A method for producing a laminate according to Item 8.   The method for producing a laminate according to claim 9, wherein the metal thin film precursor is cuprous oxide fine particles.   A layered product manufactured by the method for manufacturing a layered product according to any one of claims 7 to 10.   The printed wiring board produced using the laminated body in any one of Claims 1-6.

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