Metal-resin bonded body and its manufacturing method

Abstract

To provide a high-reliability composite having a sintered metal particulate layer and a resin layer, and a method for producing the composite.SOLUTION: A composite disclosed herein is a composite of a metal layer composed of sintered metal particulates and a resin layer composed of a resin. The metal layer is at least partially combined with the resin layer. The resin layer has internal metal particles therein. At least some of the internal metal particles are sintered with the sintered metal particulates.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a bonded body including a sintered layer made of metal fine particles such as gold, silver, palladium, etc., and a resin layer made of resin. The present invention further relates to a method for producing such a bonded body. [Background technology]

[0002] In recent years, a bonded body of a metal fine particle sintered body layer made of metal fine particles and a resin layer made of resin has been developed for various applications. For example, the following Patent Document 1 describes that a bonded body of a copper fine particle sintered body layer and a polyimide film is used as a substrate for printed wiring boards for small electrical devices. Such a bonded body is produced by subjecting one side of a polyimide film to an alkali treatment, applying a conductive ink containing copper fine particles to the side to form a coating film, drying the coating film, and then baking it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-114680 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, the technology described in Patent Document 1 uses copper fine particles, but currently, there is a demand for a bonded body having a metal fine particle sintered body layer made of precious metals such as gold and silver as well as copper. However, in the technology of Patent Document 1, the bond with the resin is maintained by metal oxides and bases derived from metal oxides, so it seems difficult to obtain a bonded body having a high bond strength with a sintered body layer made of various metals including precious metals. In addition, low-temperature sintered metal fine particles that can be sintered at or below the heat resistance temperature of the resin have high sinterability, and sintering of the fine particles progresses at an early stage of the sintering process, so there is also a problem that reactivity and bondability with the resin layer is lost, making it difficult to realize a highly reliable bonded body.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a highly reliable bonded body including a metal microparticle sintered body layer and a resin layer. Another object of the present invention is to provide a method for manufacturing such a bonded body. [Means for solving the problem]

[0006] According to the present invention, there is provided a bonded body of a metal layer (i.e., a metal microparticle sintered body layer) made of a metal microparticle sintered body and a resin layer made of a resin. The bonded body is characterized in that at least a part of the metal layer is bonded to the resin layer, metal particles are present in the resin layer, and at least a part of the present metal particles are sintered to the metal microparticle sintered body. In the bonded body having such a configuration, high bonding strength can be achieved by bonding the metal layer to the resin layer and sintering the metal microparticles to the present metal particles. In this specification and claims, the term "metal fine particles" refers to a group of many fine particles (i.e., particles), except when referring to a single particle. For example, the metal fine particles in the <metal fine particle dispersion> described below refer to metal fine particles as particles, not individual particles. In Japanese, it is unclear whether to use the singular or plural number, so the above definition is used to clarify the meaning of "metal fine particles."

[0007] In a preferred embodiment of the bonded body disclosed herein, the boundary surface between the metal layer and the resin layer has micropores toward the inside of the resin layer, and the metal microparticle sintered body penetrates at least a part of the micropores, and when the opening diameter of the micropore in the FE-SEM cross-sectional image of the boundary surface is a and the distance from the center of the opening diameter a to the deepest part of the micropore into which the metal microparticle sintered body penetrates is b', the opening diameter a is 0.5 μm or more and 10 μm or less, and the distance b' is 0.5 μm or more. In the bonded body having such a configuration, the metal microparticle sintered body in the micropores plays a role of a so-called anchor effect, so that high bonding strength can be realized.

[0008] More preferably, when 100 or more micropores having an opening diameter a of 0.5 μm or more and 10 μm or less and a distance b of 0.5 μm or more are detected (randomly detected), where the distance b from the center of the opening diameter a to the deepest part of the micropore is b in an FE-SEM cross-sectional image of the boundary surface, 60% or more of the micropores have the distance b' of 0.5 μm or more. In a bonded body having such a configuration, the anchor effect is more suitably exerted, and therefore a higher bonding strength can be realized.

[0009] In a preferred embodiment of the bonded body disclosed herein, the main constituent metal element of the metal fine particles constituting the metal fine particle sintered body is a noble metal element. Since noble metal particles tend to sinter together, they are suitable targets for application of the technology disclosed herein.

[0010] In a preferred embodiment, the main metal element of the metal fine particles constituting the metal fine particle sintered body is gold (Au). Among precious metal particles, gold particles in particular are suitable for application of the technology disclosed herein because the particles tend to sinter together.

[0011] In a preferred embodiment of the bonded body disclosed herein, the resin contains a thermosetting resin as a constituent element. The technology disclosed herein can be suitably implemented using a thermosetting resin.

[0012] In a preferred embodiment, the resin contains a thermosetting epoxy resin as a component. Among thermosetting resins, epoxy resins in particular have high heat resistance, and therefore can provide highly reliable bonded bodies.

[0013] In a preferred embodiment of the bonded body disclosed herein, the metal layer has a density of 80% or more. When the metal layer has a high density as described above, a bonded body having a low volume resistivity and good electrical conductivity can be obtained. The details of "density" in this specification and claims are described in <Density of metal layer>.

[0014] The present invention also provides a method for producing the bonded structure disclosed herein. Specifically, the method is for producing a bonded structure comprising a metal layer made of metal fine particles having an imine compound supported on the surface thereof and a resin layer made of a resin, the method comprising the steps of: The method includes preparing a dispersion containing the metal fine particles, applying the dispersion to a surface of a molded body made of the uncured resin (wherein the molded body contains metal particles), heating the molded body to which the dispersion has been applied in a temperature range in which the metal fine particles can be sintered to form the metal layer, and curing the molded body to form the resin layer. This method for producing a bonded body allows for a highly reliable bonded body having a desired strength to be obtained. In this specification and the claims, the term "dispersion" refers to a dispersion of metal fine particles, embedded metal particles, resin, etc. in a solvent, and may also include a paste-like composition, a slurry-like composition, an ink-like composition, a paint, etc.

[0015] In a preferred embodiment of the method for producing a conjugate disclosed herein, the imine compound has the following structural formula: R 0 R 1 C=N-(CH2)-R2 where R 0 is hydrogen, and R 1 and R 2 are each a hydrocarbon group having 3 to 7 carbon atoms. Such imine compounds (e.g., alkylimines) having a relatively low molecular weight and short hydrocarbon group can be easily removed by low-temperature firing at 300°C or less, and therefore a bonded body having a dense metal layer can be easily produced. [Brief description of the drawings]

[0016] [Figure 1] 1 is a pyrolysis GCMS spectrum obtained for a fine gold particle powder material produced in an example described later. [Diagram 2] This is the MS spectrum of the peak (■) of the imine compound in FIG. [Diagram 3] 1 is an FE-SEM observation image (50,000 times) of a gold fine particle powder material produced in an example described later. [Figure 4] 1 is an FE-SEM observation image (magnification: 5,000) of the interface between a gold fine particle sintered body layer and a gold particle-containing thermosetting epoxy resin layer in Example 2. [Diagram 5] 13 is an FE-SEM observation image (magnification: 5,000) of the interface between a gold fine particle sintered body layer and a gold particle-containing thermosetting epoxy resin layer in Example 5. [Figure 6] 1 is an FE-SEM observation image (magnification: 5,000) of the interface between a gold fine particle sintered body layer and a gold particle-containing thermosetting epoxy resin layer in Comparative Example 1. [Figure 7] 1 is an FE-SEM observation image (magnification: 5,000) of the interface between a gold fine particle sintered body layer and a gold particle-containing thermoplastic polyimide resin layer according to Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Preferred embodiments of the present invention will be described below. Note that matters other than those specifically mentioned in this specification that are necessary for carrying out the present invention can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present invention can be carried out based on the contents disclosed in this specification and the technical common sense in the relevant field. In this specification and claims, when a certain numerical range is described as A to B (A and B are arbitrary numerical values), it means A or more and B or less. Therefore, the case where it is more than A and less than B is also included.

[0018] <Metal fine particles> The metal fine particles in the bonded body and the manufacturing method of the bonded body disclosed herein are not particularly limited as long as the effects of the present invention can be obtained. Typical examples include gold (Au), silver (Ag), palladium (Pd), platinum (Pt), rhodium (Rh), and the like, or alloys thereof. In addition, from the viewpoint of being suitable as a target for applying the technology disclosed herein, it is preferable that the main constituent metal element is gold (Au). Here, the main constituent metal element refers to the metal element that is the main constituent of the metal microparticles. The metal microparticles disclosed herein are ideally composed only of metal elements, but may contain various metal elements and nonmetallic elements as impurities. The organic matter content of the total weight (100 wt%) of the metal microparticles (referring to the aggregate before firing) measured based on TG-DTA is preferably approximately 2 wt% or less, more preferably 1.5 wt% or less, and particularly preferably 1 wt% or less.

[0019] The method for producing a bonded body disclosed herein is characterized in that an imine compound is held on the surfaces of the metal fine particles. By holding the imine compound on the surfaces of the metal fine particles, high dispersion stability can be obtained. Methods for producing such metal microparticles include, as in the reaction system described in the Examples below, a method of preparing a mixture of a metal salt or metal complex (e.g., chloroauric acid (HAuCl4) when the metal is gold) that is soluble in a specific alcohol-based solvent and serves as the raw material for the metal microparticles, a sufficient amount of alkylamine (e.g., 3 molar equivalents or more) relative to the metal, and an alcohol-based solvent that can dissolve the raw material, such as an alkyl alcohol, and heating the mixture to, for example, 80° C. or higher. This reduces metal ions from the metal salt or complex, generating metal microparticles. The reduction treatment time for the metal ions can be appropriately set and is not particularly limited, but is preferably, for example, about 0.5 hours to 5 hours. The metal fine particles generated by the reduction treatment as described above may be collected in the same manner as conventional metal particle collection, and there is no particular restriction. Preferably, the metal fine particles generated in the liquid are allowed to settle, and the supernatant is removed by centrifuging. Preferably, washing and centrifugation are repeated multiple times with an appropriate dispersion medium, and the metal fine particles are dispersed in the appropriate dispersion medium, thereby obtaining a desired dispersion of metal fine particles. Furthermore, a paste (slurry) composition (e.g., a conductor paste for forming an electrode film, etc.) can be prepared by adding components such as a binder.

[0020] Preferably, the imine compound produced in the above reaction system and held on the surface of the metal fine particles has a relatively small molecular weight, specifically, an alkylimine having a hydrocarbon group with about 10 or less carbon atoms, for example, 4 to 10 carbon atoms, such as an alkylimine represented by the structural formula: R 0 R 1 C=N-(CH2)-R 2 It is a compound represented by R 0 , R 1 and R 2 are each independently a partially substituted or unsubstituted alkyl group or hydrogen. 0 is hydrogen and R 1 and R 2are each a hydrocarbon group having a carbon number of 3 to 9 (more preferably 3 to 7). Such imine compounds (e.g., alkylimines) having a relatively low molecular weight and short hydrocarbon group can be easily eliminated by low-temperature firing at 300° C. or less, so that a bonded body having a dense metal layer can be easily produced. For example, an imine compound of the above structural formula, R 0 is hydrogen and R 1 and R 2 are specifically preferred examples where each is CH3(CH2)6, CH3(CH2)4, or CH3(CH2)2.

[0021] This type of imine compound having a relatively small molecular weight and short chain length can be produced selectively (preferentially) by selecting the alcohol solvent and the primary amine used in the reaction system. For example, when octanol (CH3(CH2)7OH) is used as the alcohol solvent and octylamine (CH3(CH2)7NH2) is used as the primary amine, the imine compound produced has the structure shown in the above formula: 0 is hydrogen, and R 1 and R 2 can be CH3(CH2)6. Alternatively, if the primary amine is replaced with butylamine (CH3(CH2)3NH2) in this reaction system, the resulting imine compound will have R 0 is hydrogen, and R 1 and R 2 At least one of may be CH3(CH2)2. Alternatively, in this reaction system, when the primary amine is replaced with hexylamine (CH3(CH2)5NH2), the resulting imine compound has the above structural formula: 0 is hydrogen, and R 1 and R 2 At least one of the may be CH3(CH2)4. In this way, in the above reaction system, the molecular weight of the imine compound produced (in other words, R 0 , R1 , R 2 The composition of the mixture can be varied as appropriate. As will be apparent from the description of the Examples below, the structure of the produced imine compound can be identified by measuring a pyrolysis GCMS spectrum.

[0022] Regarding the particle size distribution of the metal fine particles, the ratio of the Z-average particle size (DDLS) based on the dynamic light scattering (DLS) method to the average particle size (DSEM) based on a field emission scanning electron microscope image (FE-SEM image), DDLS / DSEM, is preferably 2 or less. Metal fine particles having such characteristics have particularly excellent dispersibility, and can contribute to miniaturization of electronic components and thinning of electrodes in the electronic materials field. In addition, metal fine particles having a relatively small average particle size, such as a Z-average particle size (DDLS) of 200 nm or less, can further preferably promote thinning of electrodes, improvement of reliability, etc. It is more preferable that the DDLS is 150 nm or less, and particularly preferably, for example, 50 nm or more and 150 nm or less.

[0023] <Metal fine particle dispersion> The metal fine particle dispersion in the bonded body manufacturing method disclosed herein can be obtained by dispersing the above-mentioned metal fine particles in a dispersion medium made of an appropriate aqueous solvent or organic solvent. For example, a composition prepared in a paste form (conductor paste) can be provided by dispersing metal particles in a predetermined organic solvent and adding components such as a binder, a conductive material, a viscosity modifier, etc., as necessary. Since such a conductor paste contains metal particles whose Z-average particle size is controlled to the submicron range as described above, it is possible to suitably form a sufficiently thin-layered electrode. The dispersion medium of the conductor paste may be any one that can disperse the conductive powder material well, as in the conventional case, and any one that is used in the preparation of conventional conductor pastes may be used without any particular restrictions. For example, as the organic solvent, one or a combination of high-boiling organic solvents such as mineral spirits (particularly aliphatic hydrocarbons), cellulose polymers such as ethyl cellulose, ethylene glycol and diethylene glycol derivatives, toluene, xylene, butyl carbitol (BC), and terpineol may be used.

[0024] A suitable dispersion medium for preparing the metal microparticle dispersion includes a cyclic alcohol having a hydroxyl group on a cyclic chain. By including a cyclic alcohol as a dispersion medium, high dispersion stability can be achieved. Suitable examples include cyclic alcohols having a 5- to 8-membered ring. For example, terpineol, menthanol (dihydroterpineol), menthol (2-isopropyl-5-methylcyclohexanol), cyclopentanol, cyclohexanol, cycloheptanol, and the like can be mentioned. These cyclic alcohols may be used alone or in combination of two or more. There is no particular restriction on the content of the cyclic alcohol, but it is appropriate that the content is 10 to 100% by mass, and preferably 70 to 100% by mass, of the entire dispersion medium.

[0025] <Resin> The resin in the bonded body and the method for producing the bonded body disclosed herein is not particularly limited as long as the effects of the present invention can be obtained, but from the viewpoint of obtaining a bonded body with high reliability, a resin with a high glass transition temperature (Tg) is preferably used. Specific examples include thermosetting polyimide resins and thermosetting epoxy resins. The Tg of the thermosetting epoxy resin that can be used in the present invention is typically 100 to 150°C.

[0026] <Internal metal particles> The resin is characterized by containing metal particles (hereinafter, such metal particles are also referred to as "internal metal particles"). The internal metal particles are sintered with the metal microparticle sintered body constituting the metal layer, and the strength of the resulting bonded body is suitably improved. The internal metal particles are not particularly limited as long as the effects of the present invention can be obtained, but those listed in the description of the metal fine particles above can be preferably used. In addition, gold particles can be preferably used from the viewpoint of high sinterability and easy sintering with the metal fine particle sintered body constituting the metal layer.

[0027] <Density of metal layer> In this specification and claims, "density" refers to the value calculated by determining the area of ​​black voids (i.e., hollow parts) from a 10,000x FE-SEM cross-sectional image of an object (e.g., a metal layer) using image analysis software "Image Pro" manufactured by Media Cybernetics, Inc., and calculating density (%) = 1-(void area / total area)%. A metal layer with high density can have a low volume resistivity and good electrical conductivity. The density is preferably 80% or more, more preferably 85% or more, further preferably 90% or more, and particularly preferably 95% or more (the upper limit of the density is 100%).

[0028] <Micropore> In this specification and claims, a, b, and b' are used as parameters representing the state of the micropores. a can also be referred to as the opening diameter of the micropore in an FE-SEM cross-sectional image showing the boundary between the metal layer and the resin layer, or the distance between the metal particles (i.e., between the internal metal particles) present in the opening of the resin at the boundary (see FIG. 4, etc.). b can also be referred to as the distance from the center of the opening diameter a to the deepest part of the micropore, or the length of a line segment that connects the center of the opening of the micropore through the metal microparticle sintered body in the opening to the deepest part of the opening. If the shape inside the opening is complex and the length to the deepest part cannot be expressed by one line segment, another line segment is added, and the sum of these line segments is b. b' is the distance from the center of the opening diameter a to the deepest part of the micropore into which the metal microparticle sintered body has entered (see FIG. 4, etc.). As with b, if the shape inside the opening is complex and one line segment cannot represent the length to the part where the metal sintered body has entered, another line segment is added, and the sum of these line segments is b'. Here, preferably, the value of a is 0.5 μm to 10 μm, and the value of b' is 0.5 μm to 10 μm. Also, a may be 0.5 μm to 3 μm, and b' may be 0.5 μm or more, a may be 1 μm to 3 μm, and b' may be 1 μm or more, or a may be 2 μm to 3 μm, and b' may be 2 μm or more.

[0029] Below, as an example of the bonded structure disclosed herein, an example of a bonded structure between a gold fine particle sintered body layer and a gold particle-containing thermosetting epoxy resin layer will be described, but such an example is not intended to limit the present invention.

[0030] <1. Example of gold particle production> 50 mL of octanol (Fujifilm Wako Pure Chemical Industries, Ltd.) was added to 20.5 g of chloroauric acid tetrahydrate (Insuisho Precious Metals Chemical Co., Ltd.), and the resulting solution was cooled and stirred in an ice bath. Next, n-octylamine (a product of Fujifilm Wako Pure Chemical Industries, Ltd.) was added little by little to the above solution while suppressing heat generation, so as to prepare a chloroauric acid-octylamine complex formation solution, in an amount equivalent to 10 molar equivalents of the gold content. This complex-forming solution was subjected to a reduction treatment in which it was heated in an oil bath at 140°C in an air atmosphere for 3 hours while being stirred, thereby reducing the gold ions and synthesizing gold nanoparticles. The reaction solution was then cooled naturally, industrial alcohol (a product of Amakasu Chemical Industry Co., Ltd.) was added, the gold particles were allowed to settle, and the supernatant was removed by decantation. This procedure was repeated three times, after which industrial alcohol was added and the mixture was centrifuged at 3000 rpm for three minutes at least two times (three times in this case) and the supernatant was removed. The mixture was then dried at room temperature for 12 hours to obtain a dry powder material consisting of gold particles.

[0031] <2. Evaluation test of gold particles> (1) Characteristics of gold nanoparticles A field emission scanning electron microscope (FE-SEM: Hitachi High-Technologies Corporation, S-4700) was used to observe the gold particles in the powder material (see Figure 3). Specifically, five images were randomly selected from a 100,000x or 50,000x field of view, and the particle sizes of 40 independent particles were measured. The average particle size (DSEM) was calculated from the particle sizes of a total of 200 particles. The results are shown in the relevant columns in Table 1.

[0032] In addition, for the above powder materials, a Zetasizer Nano ZS (a product of Malvern Panalytical Co., Ltd.) was used to prepare samples of appropriate concentration by ultrasonic dispersion using N,N-dimethylformamide (DMF) as a dispersion medium, DLS measurement was performed at 20°C, and the Z-average particle size (DDLS) was calculated based on the general cumulant method. The results are shown in the corresponding columns of Table 1.

[0033] In addition, a thermal analysis of the gold microparticles (dry powder material) was performed on the above powder material using a thermogravimetric analyzer (Rigaku Corporation product, TG-DTA / H). Specifically, approximately 20 mg of the above powder material was heated from room temperature to 400°C at a rate of 10°C / min, and the thermal behavior was observed when held at 400°C for 50 minutes. The weight loss rate at this time was taken as the organic matter content in the total weight (100wt%) of the gold microparticles (dry powder). The results are shown in the relevant columns in Table 1.

[0034] (2) Detection of imine compounds The powder materials were analyzed using a pyrolysis GCMS device (Shimadzu Corporation, GCMS-QP2010 Ultra). Specifically, approximately 20 mg of dry gold particle powder was heated at 300°C for 18 seconds to cause pyrolysis, and the gas components generated from the sample were measured by GCMS. The column used was a Frontier Labs Ultra ALLOY±5 (UA5-30M-0.25F), and the column oven temperature was raised from 40°C to 320°C at a rate of 10°C / min, and held at 320°C for 32 minutes. The ionization method used by the mass spectrometer was the electron impact method (EI method). The obtained pyrolysis GCMS spectrum is shown in Figure 1. Moreover, the MS spectrum of the detected peak of the imine compound (peak ■ in the corresponding pyrolysis GCMS spectrum) is shown in Figure 2.

[0035] The imine compounds identified were as follows: [Imine compounds] Structural formula: R 0 R 1 C=N-(CH2)-R 2 An imine compound represented by the formula: 0 is hydrogen and R 1 and R 2 are CH3(CH2)6, respectively. Hereinafter, this will be referred to as imine compound A. Identification method Since the MS spectrum data of the above imine compound was not present in the GCMS library, the imine compound (R 0is hydrogen, and the above R 1 and R 2 The compounds were identified by reference to the MS spectrum data of the corresponding imine compounds (each of which is CH3(CH2)2).

[0036] [Table 1]

[0037] As shown in Table 1, the gold particles in the powder material had a DDLS / DSEM of 2 or less, and it was confirmed that the gold particles had good dispersibility. In addition, the Z-average particle size (DDLS) was 150 nm or less, and it was confirmed that the powder material is good for contributing to miniaturization of electronic components and thinning of electrodes. Furthermore, when the total weight of the gold particles (dry powder) was taken as 100 wt%, the organic matter content (here, the content of imine compounds present on the surface of the gold particles) was 0.61 wt%. Therefore, since the amount of imine compounds adsorbed on the surface of the gold particles is small, it is considered that the volume change due to burn-out during sintering is small, and a sintered body with high density can be obtained. Furthermore, as shown in the relevant column of Table 1, the powder material did not detect a large exothermic peak (due to oxidation) at 200°C or higher, which is seen in gold particles carrying alkylamines, in TG-DTA (TG-DTA curve not shown). Furthermore, pyrolysis GCMS at 300°C confirmed that the main component was an imine compound (alkylimine compound: see structural formula above). This indicates that the organic molecules present on the surface of the gold particles are converted from alkylamines to the above alkylimine compounds in the reaction system in which the gold particles are synthesized, and that almost no amine added to the reaction system remains.

[0038] <3. Example of manufacturing gold particle dispersion> Menthol, a cyclic alcohol, was added as a dispersion medium to the powder material, and the mixture was left to stand for 3 hours or more.The mixture was then centrifuged to replace the solvent. Menthol was added to the obtained wet powder so that the weight of the gold particles was 80 to 90 wt % of the total amount, and the mixture was mixed and dispersed using a planetary centrifugal mixer to prepare a gold particle dispersion.

[0039] <4. Manufacturing example of gold particle-containing thermosetting epoxy resin paint> A thermosetting epoxy resin was dissolved in terpineol C and mixed with gold particles and a novolac-type phenolic resin curing agent to prepare a gold particle-containing thermosetting epoxy resin paint (in the following description, this paint will also be referred to simply as "epoxy resin paint").

[0040] <5. Example of manufacturing a bonded body having a gold fine particle sintered body layer and a gold particle-containing thermosetting epoxy resin layer> Example 1: The epoxy resin coating was applied onto a tungsten substrate and dried at 60°C for 1 hour. As a result, a molded body made of gold particle-containing thermosetting epoxy resin (hereinafter also simply referred to as "epoxy resin molded body") was formed on the tungsten substrate. At this time, the epoxy resin molded body lost fluidity and was weakly bonded to the tungsten substrate. Next, the gold microparticle dispersion was applied onto the surface of the epoxy resin molded body, and after drying at 60°C for 1 hour, the temperature was increased at 10°C / min and heat-treated at 250°C for 30 minutes to sinter and harden the epoxy resin molded body. As a result, a tungsten-gold particle-containing thermosetting epoxy resin layer-gold microparticle sintered body layer bonded body (hereinafter also simply referred to as "bonded body") was obtained. Example 2: The gold fine particle dispersion was applied to the surface of the epoxy resin molded body, and the gold fine particle dispersion was dried, and then the heat treatment was performed at a temperature increase rate of 10° C. / min at 280° C. for 50 minutes. The same procedure as in Example 1 was repeated, but a bonded body was obtained. Example 3: The gold fine particle dispersion was applied to the surface of the epoxy resin molded body, and the gold fine particle dispersion was dried, and then the heat treatment was performed at a temperature increase rate of 10° C. / min at 300° C. for 30 minutes. The same procedure as in Example 1 was carried out. As a result, a bonded body was obtained. Example 4: The epoxy resin coating was applied onto a tungsten substrate and dried at 130°C for 15 minutes. As a result, a molded body (i.e., an "epoxy resin molded body") made of a gold particle-containing thermosetting epoxy resin was formed on the tungsten substrate. At this time, the epoxy resin molded body lost its fluidity and was weakly bonded to the tungsten substrate. Next, the gold particle dispersion was applied onto the surface of the epoxy resin molded body, and after drying at 60°C for 1 hour, the temperature was increased at 10°C / min and heat-treated at 250°C for 30 minutes to sinter and harden the epoxy resin molded body. As a result, a bonded body was obtained. Example 5: The gold fine particle dispersion was applied to the surface of the epoxy resin molded body, dried, and then the heat treatment was performed at a temperature increase rate of 10°C / min at 280°C for 50 minutes, in the same manner as in Example 4. As a result, a bonded body was obtained. Example 6: The gold fine particle dispersion was applied to the surface of the epoxy resin molded body, dried, and then the heat treatment was performed at a temperature increase rate of 10° C. / min at 300° C. for 30 minutes, in the same manner as in Example 4. As a result, a bonded body was obtained.

[0041] Comparative Example 1: The epoxy resin coating was applied to a tungsten substrate, dried at 130°C for 15 minutes, and then heat-treated at 180°C for 1 hour to harden the epoxy resin. At this time, the obtained gold particle-containing thermosetting epoxy resin layer (hereinafter also simply referred to as "epoxy resin layer") was in a state of being bonded to the tungsten substrate. Next, the gold microparticle dispersion was applied to the surface of the epoxy resin layer, dried at 60°C for 1 hour, heated at 10°C / min, and heat-treated at 280°C for 50 minutes to perform sintering. As a result, a bonded body was obtained, but as can be seen from the FE-SEM cross-sectional image (FIG. 6), the bond of the bonded body was mainly due to sintering between the gold microparticles and the gold particles contained in the epoxy resin. In such a bonding mode, the area of ​​the bonding surface is small, so it is difficult to obtain high bonding strength.

[0042] <6. Example of manufacturing thermoplastic polyimide resin paint containing gold particles> A thermoplastic polyimide resin containing gold particles was prepared by dissolving the thermoplastic polyimide resin in γ-butyrolactone and kneading the gold particles therein (in the following description, such a paint will also be referred to simply as “polyimide resin paint”).

[0043] Comparative Example 2: The polyimide resin coating was applied onto a tungsten substrate and dried at 60°C for 1 hour. As a result, a molded body made of a thermoplastic polyimide resin containing gold particles (hereinafter also simply referred to as a "polyimide resin molded body") was formed on the tungsten substrate. At this time, the solvent in the polyimide resin coating remained in the polyimide resin molded body, and the polyimide resin molded body was in a flexible state and weakly bonded to the tungsten substrate. Next, the gold microparticle dispersion was applied onto the surface of the polyimide resin molded body, and after drying at 60°C for 1 hour, the temperature was increased at 10°C / min and heat-treated at 280°C for 50 minutes to sinter and solidify the polyimide resin molded body. As a result, although a bonded body was obtained, as can be seen from the FE-SEM cross-sectional image (Figure 7), the bond of the bonded body was mainly a bond between the gold microparticle sintered body layer and the gold particle-containing thermosetting epoxy resin layer. With such a bonding mode, it is difficult to obtain high bonding strength.

[0044] <7. Direct formation of a gold particle sintered layer on a substrate> Comparative Example 3: The gold particle dispersion was applied to a glass substrate using a metal mask of 1 cm x 1 cm x 100 μm and squeezed with a rubber squeegee. After drying at 60°C for 1 hour, it was heat-treated at 300°C for 30 minutes. As a result, the gold particle sintered body layer obtained did not adhere to the glass substrate and became a separate film. Comparative Example 4: Except for applying the above gold fine particle dispersion onto a tungsten substrate, the same operation as in Comparative Example 4 was carried out. As a result, the obtained gold fine particle sintered body layer did not adhere to the glass substrate and was a single film. Comparative Example 5: Except for coating the gold fine particle dispersion on a gold substrate, the same operation as in Comparative Example 4 was carried out. As a result, the obtained gold fine particle sintered body layer did not adhere to the gold substrate and was a single film.

[0045] <8. Evaluation test of the conjugate> [Tape peeling test] A peel test was carried out by attaching cellophane tape to the bonded bodies obtained in Examples 1 to 6 and peeling it off. The test results are shown in the corresponding columns in Table 2.

[0046] [Evaluation of density of gold fine particle sintered layer] The cross sections of the bonded bodies obtained in Examples 1 to 6 were subjected to ion milling. The areas of the black voids (i.e., hollow parts) were obtained from the FE-SEM cross-sectional images of each of the ion-milled polished surfaces obtained at a magnification of 10,000 times using the image analysis software "Image Pro" manufactured by Media Cybernetics, and the compactness (%) was calculated as 1-(void area / total area)%. The results are shown in the corresponding columns of Table 2.

[0047] [Table 2]

[0048] [Observation of micropores] The micropores present at the boundary between the gold microparticle sintered body layer and the gold particle-containing thermosetting epoxy resin layer of the bonded bodies according to Examples 1 to 6 were evaluated. First, in a 5,000-fold FE-SEM cross-sectional image of each boundary, it was confirmed that the opening diameter a of the micropores present at the boundary was 0.5 μm to 10 μm and the distance b' was 0.5 μm or more, when the opening diameter a was a and the distance b' was b', when 100 or more micropores were detected in which the opening diameter a was 0.5 μm to 10 μm and the distance b was 0.5 μm or more, when the distance b from the center of the opening diameter a to the deepest part of the micropore was b, it was confirmed that 60% or more of the micropores had the distance b' of 0.5 μm or more. The values ​​of a and b of several examples (three examples in total here) of the 100 or more micropores present at the boundary surface between the gold particle-containing thermosetting epoxy resin layer and the gold fine particle sintered body layer of the bonded bodies according to Examples 2 and 5 are shown in Table 3. The morphology of such micropores is shown in Figs. 4 and 5.

[0049] [Table 3]

[0050] As shown in Tables 2 and 3, in the bonded bodies according to Examples 1 to 6, which were obtained by applying a dispersion containing gold particles with an imine compound held on the surface of an uncured gold particle-containing thermosetting epoxy resin molded body formed on a tungsten substrate and then performing a heat treatment at a temperature of 300°C or less, it was confirmed that bonded bodies with high bonding strength that did not peel off even in a tape peeling test were obtained. Furthermore, as shown in Table 2, it was confirmed that the density of the gold particle sintered body layer of the bonded bodies according to Examples 1 to 6 was high, at 80% or more. Therefore, it was confirmed that bonded bodies with good conductivity and low volume resistivity were obtained. In this manner, according to the bonded body disclosed herein, it is possible to provide a highly reliable bonded body including a metal fine particle sintered body layer and a resin layer.

Claims

1. A bonded body including a metal layer made of a sintered body of metal fine particles and a resin layer made of a resin, the metal layer is bonded to a resin layer, the resin layer contains metal particles, and at least a portion of the contained metal particles is sintered with the metal microparticle sintered body; a boundary surface between the metal layer and the resin layer has micropores toward the inside of the resin layer; The metal microparticle sintered body is inserted into at least a part of the micropores, Here, when the opening diameter of the micropore in the FE-SEM cross-sectional image reflecting the boundary surface is a and the distance from the center of the opening diameter a to the deepest part of the micropore into which the metal microparticle sintered body has penetrated is b', there are micropores in which the opening diameter a is 0.5 μm or more and 10 μm or less and the distance b' is 0.5 μm or more, In an FE-SEM cross-sectional image of the boundary surface, the distance from the center of the opening diameter a to the deepest part of the micropore is b, and 100 or more micropores are detected in which the opening diameter a is 0.5 μm or more and 10 μm or less and the distance b is 0.5 μm or more, and 60% or more of the micropores have the distance b' of 0.5 μm or more.

2. A bonded body including a metal layer made of a sintered body of metal fine particles and a resin layer made of a resin, the metal layer is bonded to the resin layer, and metal particles are present in the resin layer; At least a part of the contained metal particles is sintered with the metal microparticle sintered body, and micropores are present at the interface between the metal layer and the resin layer toward the inside of the resin layer, The metal microparticle sintered body is inserted into at least a part of the micropores, Here, when the opening diameter of the micropore in the FE-SEM cross-sectional image reflecting the boundary surface is a and the distance from the center of the opening diameter a to the deepest part of the micropore into which the metal microparticle sintered body has penetrated is b', there are joints in which the opening diameter a is 2 μm or more and 3 μm or less and the distance b' is 2 μm or more.

3. 3. The joined body according to claim 1, wherein a main constituent metal element of the metal fine particles constituting the metal fine particle sintered body is a noble metal element.

4. The bonded body according to claim 1 , wherein the resin is a thermosetting resin.

5. The joint body according to claim 1 , wherein the resin is a thermosetting epoxy resin.

6. The joined body according to claim 1 , wherein the metal layer has a density of 80% or more.

7. A method for producing a bonded body including a metal layer made of metal fine particles having an imine compound supported on a surface thereof and a resin layer made of a thermosetting resin having metal particles therein, the method comprising the steps of: preparing a dispersion containing the metal fine particles; applying the dispersion onto a surface of a molded article made of the uncured resin; and heating the molded body coated with the dispersion in a temperature range in which the metal fine particles are sinterable and the curable resin is heat-curable, thereby forming the metal layer on the surface of the heat-cured resin layer; A method for manufacturing a joint body comprising the steps of:

8. The method for producing a joint body according to claim 7 , wherein the molded body has a thickness of the resin layer greater than the particle diameter of the contained metal particles.

9. 9. The method for manufacturing a joint body according to claim 7, wherein the resin comprises a thermosetting epoxy resin as a constituent element.

10. The imine compound has the following structural formula: R ０ R １ C=N-(CH ２ )-R ２ A compound represented by the formula: Here, R ０ is hydrogen, R １ and R ２ and each of are a hydrocarbon group having 3 to 7 carbon atoms.

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