Adhesive film, adhesive film with metal layer, wiring formation member, formation method for wiring layer, and wired member

Abstract

A wiring formation member 1 that is one example of an adhesive film with a metal layer comprises a metal layer 20 and an adhesive layer 10 that is provided on the metal layer 20. The adhesive layer 10 includes conductive particles 12 and a curable resin composition. A cured product of the adhesive layer 10 has a coefficient of thermal expansion of 1.5%–3.0% when heated from 40°C to 260°C.

Description

Adhesive film, adhesive film with metal layer, wiring-forming member, method for forming wiring layer, and wiring-forming member

[0001] The present disclosure relates to an adhesive film, an adhesive film with a metal layer, a wiring-forming member, a method for forming a wiring layer, and a wiring-forming member.

[0002] Japanese Patent Application Laid-Open No. 2003-144222 discloses a method for manufacturing a printed wiring board incorporating electronic components such as IC chips.

[0003] JP 2012-191204 A

[0004] In a conventional method for manufacturing a component-embedded substrate, as shown in FIGS. 8A and 8B, insulating resin layers 102 and 103 are formed on both sides of an electronic component 101 having an electrode 101a in the stacking direction. Then, as shown in FIGS. 8C and 8D, via electrodes 104 and 105 are formed in the insulating resin layers 102 and 103, respectively, by performing laser drilling, plating layer formation, and electrode formation by etching. Then, as shown in FIGS. 9A to 9C, the component-embedded substrate 110 is formed by repeatedly forming further insulating resin layers 106 and 107, forming via electrodes 108 by laser drilling and plating layer formation, and electrode formation by etching. However, in this method for manufacturing a component-embedded substrate, many processes are performed to form one conductive layer (via electrode), and these processes must be repeated to form multiple conductive layers, making the manufacturing process very complicated.

[0005] Therefore, an adhesive having a metal layer such as a metal foil laminated thereon and conductive particles was investigated as a member for forming wiring. With such a member for forming wiring, it is expected that a wiring layer connected to the wiring can be easily formed on the substrate on which the wiring has been formed by going through the steps of: placing the member for forming wiring on the substrate so that the adhesive layer faces the substrate on which the wiring has been formed;

[0006] Incidentally, the component-embedded substrates used in semiconductor packages and the like may be subjected to loads due to thermal expansion of components in high-temperature environments such as reflow processes. If excessive load is applied to the connection formed as described above, problems such as increased connection resistance due to poor conductivity, swelling, peeling, etc. may arise. On the other hand, from the standpoint of productivity and handleability, such as in roll-to-roll applications, wiring-forming components are required to have crack resistance that prevents cracks from occurring during winding. Furthermore, crack resistance during winding is also necessary when slitting the component to a specified width. However, adhesive layers designed with a resin that can form connections with enhanced heat resistance tend to be less crack-resistant.

[0007] Therefore, the present disclosure aims to provide an adhesive film that has sufficient crack resistance, can connect opposing wirings with sufficient conductivity, and can form a connection portion that has excellent connectivity even under high temperature conditions; an adhesive film with a metal layer and a wiring forming member that has sufficient crack resistance, can simplify the process of forming a wiring layer that connects wirings, and can form a wiring layer that has excellent connectivity even under high temperature conditions; and a method for forming a wiring layer using these, and a wiring forming member.

[0008] In order to solve the above problems, the present disclosure provides the following adhesive film, adhesive film with a metal layer, wiring-forming member, wiring layer forming method, and wiring-forming member.

[0009] [1] An adhesive film containing conductive particles and a thermosetting resin composition, wherein the adhesive film has a thermal expansion coefficient of 1.5 to 3% when a cured product of the adhesive film is heated from 40°C to 260°C. [2] The adhesive film according to [1], wherein the reactivity is 90% or less when heated at 180°C for 5 minutes. [3] The adhesive film according to [1] or [2], wherein the conductive particles comprise copper particles. [4] A metal layer-attached adhesive film comprising a metal layer and an adhesive layer disposed on the metal layer, wherein the adhesive layer comprises conductive particles and a thermosetting resin composition, and wherein the cured product of the adhesive layer has a thermal expansion coefficient of 1.5 to 3% when heated at 40°C to 260°C. [5] The metal layer-attached adhesive film according to [4], wherein the adhesive layer has a reactivity of 90% or less when heated at 180°C for 5 minutes. [6] The metal layer-attached adhesive film according to [4] or [5], wherein the conductive particles comprise copper particles. [7] The metal layer-attached adhesive film according to any one of [4] to [6], which is used for forming wiring. [8] A wiring-forming member in which an adhesive layer and a metal layer are provided as separate entities, and the adhesive layer can be adhered to the metal layer during use, the adhesive layer containing conductive particles and a thermosetting resin composition, and a cured product of the adhesive layer has a thermal expansion coefficient of 1.5 to 3% when heated from 40°C to 260°C. [9] The wiring-forming member according to [8], in which the adhesive layer has a reactivity of 90% or less when heated at 180°C for 5 minutes.

[10] The wiring-forming member according to [8] or [9], in which the conductive particles contain copper particles.

[11] A method for forming a wiring layer, comprising the steps of: preparing a metal layer-attached adhesive film according to any one of [4] to [6]; preparing a substrate on which wiring is formed; placing the metal layer-attached adhesive film on the surface of the substrate on which wiring is formed so as to cover the wiring, with the adhesive layer facing the substrate; heat-pressing the metal layer-attached adhesive film to the substrate; and performing a patterning process on the metal layer.

[12] A method for forming a wiring layer, comprising the steps of: preparing a wiring-forming member according to any one of [8] to

[10] ; preparing a base material on which wiring is formed; placing the wiring-forming member against the surface of the base material on which wiring is formed so that the adhesive layer faces the base material to cover the wiring; thermocompression-bonding the wiring-forming member to the base material; and patterning the metal layer.

[13] A wiring-forming member, comprising: a base material having wiring; and a cured product of the adhesive layer of the metal layer-attached adhesive film according to any one of [4] to [6], which is placed on the base material so as to cover the wiring, wherein the wiring and the metal layer of the metal layer-attached adhesive film are electrically connected.

[14] A wiring-forming member, comprising: a base material having wiring; and a cured product of the adhesive layer of the wiring-forming member according to any one of [8] to

[10] , which is placed on the base material so as to cover the wiring, wherein the wiring and the metal layer of the wiring-forming member are electrically connected to the metal layer of the wiring-forming member or another wiring formed from the metal layer.

[0010] According to the present disclosure, it is possible to provide an adhesive film that has sufficient crack resistance, can connect opposing wirings with sufficient conductivity, and can form a connection portion that has excellent connectivity even under high temperature conditions; an adhesive film with a metal layer and a wiring forming member that has sufficient crack resistance, can simplify the process of forming a wiring layer that connects wirings, and can form a wiring layer that has excellent connectivity even under high temperature conditions; and a method for forming a wiring layer using these and a wiring forming member.

[0011] FIG. 1 is a cross-sectional view showing a wiring-forming member according to one embodiment of the present disclosure. (a) to (d) of FIG. 2 are diagrams sequentially illustrating a method for forming a wiring layer using the wiring-forming member shown in FIG. 1. (a) to (c) of FIG. 3 are cross-sectional views showing wiring-forming members according to another embodiment of the present disclosure and the state when the wiring-forming members are pressure-bonded. FIG. 4 is a cross-sectional view showing a wiring-forming member according to another embodiment of the present disclosure. (a) to (d) of FIG. 5 are diagrams sequentially illustrating a method for forming a wiring layer using the wiring-forming member shown in FIG. 4. (a) to (b) of FIG. 6 are cross-sectional views sequentially illustrating an example of forming a wiring layer using the wiring-forming member shown in FIG. 4. (a) to (b) of FIG. 7 are cross-sectional views sequentially illustrating another example of forming a wiring layer using the wiring-forming member shown in FIG. 4. (a) to (d) of FIG. 8 are cross-sectional views sequentially illustrating a method for manufacturing a conventional component-embedded substrate. (a) to (c) of FIG. 9 are cross-sectional views sequentially illustrating a method for manufacturing a conventional component-embedded substrate, showing steps subsequent to those shown in FIG. 8.

[0012] Hereinafter, with reference to the drawings, an adhesive film with a metal layer and a wiring-forming member according to one embodiment of the present disclosure, as well as a method for forming a wiring layer using these and an adhesive film will be described. In the following description, the same or corresponding parts will be given the same reference numerals, and duplicate explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown.

[0013] In the present specification, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. Furthermore, in the numerical ranges described in stages in the present specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present specification, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.

[0014] The adhesive film with a metal layer of this embodiment comprises a metal layer and an adhesive layer disposed on the metal layer, the adhesive layer containing copper particles and a thermosetting resin composition, and the cured adhesive layer has a thermal expansion coefficient of 1.5 to 3% when heated from 40°C to 260°C. The adhesive film with a metal layer of this embodiment can be used to form wiring. In other words, the adhesive film with a metal layer of this embodiment may be a member for forming wiring. Details of the adhesive film with a metal layer of this embodiment will be described below, taking as an example a case where it is used as a member for forming wiring.

[0015] 1 is a cross-sectional view showing a wiring formation member according to an embodiment of the present disclosure. As shown in FIG. 1, the wiring formation member 1 is configured to include an adhesive layer 10 and a metal layer 20. The wiring formation member 1 is a member that can be used, for example, when fabricating, but not limited to, a rewiring layer, a build-up multilayer wiring board, a component-embedded substrate, and the like. The wiring formation member 1 may also be used for EMI shielding, etc.

[0016] The adhesive layer 10 includes conductive particles 12 and an insulating adhesive component 14 in which the conductive particles 12 are dispersed. The adhesive component 14 of the adhesive layer 10 is defined as solid content other than conductive particles such as the conductive particles 12. The adhesive layer 10 may be in a B-stage state, i.e., a semi-cured state, before the wiring layer is formed using the wiring-forming member 1.

[0017] [Construction of Conductive Particles] The conductive particles 12 are conductive, approximately spherical particles, and are composed of metal particles made of metals such as Au, Ag, Ni, Cu, and solder, or conductive carbon particles made of conductive carbon. The conductive particles 12 may be coated conductive particles having a core containing non-conductive glass, ceramic, plastic (polystyrene, etc.), and a coating layer containing the above metal or conductive carbon that coats the core. Among these, the conductive particles 12 may be metal particles made of a heat-fusible metal, or coated conductive particles having a core containing plastic and a coating layer containing metal or conductive carbon that coats the core. The conductive particles 12 may also be copper particles from the viewpoint of reducing the likelihood of short circuits.

[0018] In one embodiment, the conductive particles 12 include a core made of a polymer particle (plastic particle) such as polystyrene, and a metal layer covering the core. The polymer particle may have substantially the entire surface covered with the metal layer, or a portion of the surface of the polymer particle may be exposed without being covered with the metal layer, as long as the function as a connecting material is maintained. The polymer particle may be, for example, a particle containing a polymer containing at least one monomer selected from styrene and divinylbenzene as a monomer unit.

[0019] The metal layer may be formed of various metals such as Ni, Ni / Au, Ni / Pd, Cu, NiB, Ag, and Ru. The metal layer may be an alloy layer made of an alloy of Ni and Au, an alloy of Ni and Pd, or the like. The metal layer may have a multilayer structure made of multiple metal layers. For example, the metal layer may be made of a Ni layer and an Au layer. The metal layer may be formed by plating, vapor deposition, sputtering, soldering, or the like. The metal layer may be a thin film (e.g., a thin film formed by plating, vapor deposition, sputtering, or the like).

[0020] The conductive particles 12 may have an insulating layer. Specifically, for example, an insulating layer may be provided on the outer surface of the coating layer of the conductive particles of the above embodiment, which include a core (e.g., a polymer particle) and a coating layer such as a metal layer that coats the core. The insulating layer may be the outermost layer located on the outermost surface of the conductive particle. The insulating layer may be a layer formed from an insulating material such as silica or acrylic resin.

[0021] From the viewpoint of excellent dispersibility and conductivity, the average particle size Dp of the conductive particles 12 may be 1 μm or more, 2 μm or more, or 5 μm or more. From the viewpoint of excellent dispersibility and conductivity, the average particle size Dp of the conductive particles may be 50 μm or less, 30 μm or less, or 20 μm or less. From the above viewpoint, the average particle size Dp of the conductive particles may be 1 to 50 μm, 5 to 30 μm, 5 to 20 μm, or 2 to 20 μm.

[0022] The maximum particle size of the conductive particles 12 may be smaller than the smallest spacing between electrodes in the wiring pattern (the shortest distance between adjacent electrodes). From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of the conductive particles 12 may be 1 μm or more, 2 μm or more, or 5 μm or more. From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of the conductive particles may be 50 μm or less, 30 μm or less, or 20 μm or less. From the above viewpoint, the maximum particle size of the conductive particles may be 1 to 50 μm, 2 to 30 μm, or 5 to 20 μm.

[0023] In this specification, the particle diameters of 300 random particles (pcs) are measured by observation using a scanning electron microscope (SEM), the average value of the obtained particle diameters is defined as the average particle diameter Dp, and the largest value obtained is defined as the maximum particle diameter of the particle. Note that when the particle has protrusions or is not spherical, the particle diameter is defined as the diameter of the circle circumscribing the particle in the SEM image.

[0024] The content of the conductive particles 12 is determined depending on the fineness of the electrodes to be connected. For example, the amount of the conductive particles 12 is not particularly limited, but may be 0.1 vol% or more, 0.2 vol% or more, 1 vol% or more, 1.5 vol% or more, 2 vol% or more, 5 vol% or more, or 10 vol% or more, based on the total volume of the adhesive components (components in the adhesive composition excluding the conductive particles). When the amount is within these ranges, resistance unevenness and reduced conductivity tend to be suppressed. The amount of the conductive particles 12 may be 30 vol% or less, 15 vol% or less, or 10 vol% or less, based on the total volume of the adhesive components (components in the adhesive composition excluding the conductive particles 12). When the amount is within these ranges, circuit shorts tend to be less likely to occur. Note that "vol%" is determined based on the volume of each component before curing at 23°C, but the volume of each component can be converted from weight to volume using specific gravity. Alternatively, the component can be poured into a measuring cylinder or the like containing a suitable solvent (water, alcohol, etc.) that wets the component without dissolving or swelling it, and the increased volume can be determined as the volume of the component.

[0025] From the viewpoint of reducing the connection resistance between the wirings, the adhesive layer 10 may contain copper particles as the conductive particles 12. In this case, the area of ​​the wiring layer to be formed becomes large (for example, 50 mm square or more (2500 mm ２ If the pressure is more than 100 kJ / cm 2 , uneven springback of the copper particles is likely to occur due to uneven pressure, and connectivity under high temperature conditions is likely to decrease. However, by keeping the thermal expansion coefficient of the cured product (described later) within a specific range, it is possible to form a wiring layer that has excellent connectivity under high temperature conditions while reducing connection resistance.

[0026] The copper particles may be particles containing one or more of Cu and alloys of Cu with other metals. Examples of alloys of Cu with other metals include silver, zinc, nickel, gold, lead, tin, aluminum, manganese, beryllium, tungsten, and iron. From the viewpoint of reducing the connection resistance between wirings and reducing production costs, the Cu content in the copper particles may be 50% by mass or more, 70% by mass or more, or even 100% by mass.

[0027] The shape of the copper particles may be spherical, approximately spherical, flaky, columnar, rod-like, needle-like, plate-like, or fibrous.

[0028] The average particle size Dp of the copper particles may be 0.5 μm or more, 1 μm or more, or 3 μm or more from the viewpoint of reducing the connection resistance between wirings and increasing the definition of wirings. The average particle size Dp of the conductive particles may be 300 μm or less, 100 μm or less, or 50 μm or less from the viewpoint of improving insulation between adjacent wirings. From the above viewpoints, the average particle size Dp of the conductive particles may be 0.5 to 300 μm, 1 to 100 μm, or 3 to 50 μm.

[0029] The maximum particle size of the copper particles may be smaller than the minimum spacing between electrodes in the wiring pattern (the shortest distance between adjacent electrodes). From the viewpoint of reducing the connection resistance between wirings, the maximum particle size of the copper particles may be 0.5 μm or more, 1 μm or more, or 3 μm or more. From the viewpoint of improving insulation between adjacent wirings, the maximum particle size of the conductive particles may be 300 μm or less, 100 μm or less, or 50 μm or less. From the above viewpoint, the maximum particle size of the conductive particles may be 0.5 to 300 μm, 1 to 100 μm, or 3 to 50 μm.

[0030] From the viewpoint of reducing connection resistance, the content of copper particles can be 6% by volume or less, based on the total volume of the adhesive layer. When the content of copper particles is 6% by volume or less, the copper particles can be sufficiently flattened, thereby ensuring a sufficient connection area between the electrodes or wiring provided on the substrate and the metal layer. It is generally believed that the connection resistance decreases as the content of conductive particles increases. However, in the case of copper particles, when the content exceeds 6% by volume, flattening becomes difficult, making it difficult to reduce connection resistance. This finding, which can be said to be unexpected, was revealed through the studies of the present inventors. From the viewpoints of reducing connection resistance, improving insulation between adjacent wiring, and reducing manufacturing costs, the content of copper particles may be 0.1 to 6% by volume, or 0.5 to 3% by volume.

[0031] From the viewpoint of reducing connection resistance, the conductive particles 12 may satisfy one or more of the following conditions. From the viewpoint of easily obtaining good connectivity between wirings, the adhesive layer 10 may contain copper particles that satisfy one or more of the following conditions: (i) The amount of change when a pressure of 50 mN is applied per particle is 1 to 5 μm. (ii) The amount of recovery when a pressure of 50 mN is applied per particle and then released is 1 μm or less. (iii) The recovery rate, calculated by (amount of recovery when a pressure of 50 mN is applied per particle and then released) × 100 / (amount of change when a pressure of 50 mN is applied per particle), is 1 to 25%, or 1 to 5%.

[0032] The above-mentioned change and recovery amounts are determined by a microcompression test using a probe, and refer to values ​​measured under the following conditions: Measuring device: "FISCHERSCOPE HM2000" (manufactured by Fischer Instruments) Probe size (area): 100 μm × 100 μm Pressing time: Press 50 seconds / Return 50 seconds Measurement temperature: 25° C. Thrust force: 50 mN

[0033] [Configuration of Adhesive Layer / Adhesive Component] The adhesive component 14 constituting the adhesive layer 10 may be a thermosetting resin composition. Components contained in the thermosetting resin composition include a thermosetting resin, a curing agent, and a curing accelerator.

[0034] Thermosetting resins are resins that exhibit curing properties when exposed to heat. Examples of thermosetting resins include epoxy resins, polyimide resins, triazine resins such as melamine resins, phenolic resins, and modified versions of these resins. Among these, epoxy resins are preferred because they can adequately prevent bubbles or peeling during wiring formation.

[0035] The adhesive component may contain an epoxy resin and a phenol resin as thermosetting components, from the viewpoint of sufficiently suppressing the occurrence of bubbles or peeling during wiring formation and making it difficult for resistance unevenness to occur.

[0036] The epoxy resin may be any compound having two or more epoxy groups in the molecule, and examples thereof include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, biphenyl epoxy resins, biphenyl novolac epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol A novolac epoxy resins, bisphenol F novolac epoxy resins, naphthalene polyfunctional epoxy resins, dicyclopentadiene epoxy resins, alicyclic epoxy resins, aliphatic linear epoxy resins, glycidyl ester epoxy resins, isocyanurate epoxy resins, hydantoin epoxy resins, glycidyl ether compounds of polyfunctional phenols, glycidyl ether compounds of bifunctional alcohols, and hydrogenated versions thereof. Among these, novolac epoxy resins such as biphenyl novolac epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol A novolac epoxy resins, and bisphenol F novolac epoxy resins may be used from the viewpoints of ease of handling and availability. The epoxy resins may be used alone or in combination of two or more.

[0037] From the viewpoint of ensuring adhesive strength and heat resistance, the adhesive component may contain, as an epoxy resin, a compound having three or more epoxy groups in one molecule.

[0038] From the viewpoints of ensuring adhesive strength and heat resistance and of good reactivity, the epoxy resin may have an epoxy equivalent of 100 to 1,000 g / eq, 125 to 900 g / eq, or 150 to 800 g / eq. The epoxy equivalent is determined by a method standardized in JIS (K7236:2001).

[0039] The content of the epoxy resin in the adhesive component may be 5 to 95 mass %, 10 to 90 mass %, 15 to 85 mass %, or 40 to 60 mass %, based on the total amount of the adhesive component (total amount of solids other than the conductive particles in the adhesive layer 10).

[0040] The phenolic resin functions as a curing agent for the epoxy resin. Examples of the phenolic resin include novolac-type phenolic resins such as phenol novolac, cresol novolac, bisphenol A novolac, bisphenol F novolac, and catechol novolac, as well as those in which the aromatic ring is substituted with an alkyl group. One type of phenolic resin may be used alone, or two or more types may be used in combination.

[0041] From the viewpoint of ensuring adhesive strength and heat resistance, the adhesive component may contain a compound having three or more phenol groups or cresol groups per molecule as a phenolic resin. From the viewpoint of ease of handling and availability, such a compound may be a phenol novolac type phenolic resin, a cresol novolac type phenolic resin, a bisphenol A novolac type phenolic resin, or a bisphenol F novolac type phenolic resin.

[0042] The hydroxyl group equivalent of the phenolic resin may be 300 g / eq or less or 250 g / eq or less from the viewpoint of suppressing the occurrence of bubbles or peeling during wiring formation and making it less likely that uneven resistance will occur, and may be 50 g / eq or more or 100 g / eq or more from the viewpoint of ease of handling and good reactivity.

[0043] The hydroxyl equivalent of the phenolic resin can be determined by the following measurement method. <Method for Measuring Hydroxyl Equivalent> 1 g of sample is precisely weighed into a round-bottom flask, and 5 mL of acetic anhydride and pyridine test solution are also accurately weighed. Next, an air condenser is attached to the flask, and the mixture is heated at 100°C for 1 hour. After the flask is cooled, 1 mL of water is added, and the flask is again heated at 100°C for 10 minutes. After the flask is cooled again, the air condenser and the neck of the flask are rinsed with 5 mL of neutralized methanol, and 1 mL of phenolphthalein reagent is added. The solution thus obtained is titrated with a 0.1 mol / L potassium hydroxide-ethanol solution to determine the hydroxyl value. From the obtained hydroxyl value, the hydroxyl equivalent (g / eq) converted to the mass per 1 mol (1 eq) of hydroxyl groups is calculated.

[0044] The content of the phenolic resin in the adhesive component can be set so that the number of hydroxyl groups in the phenolic resin is 0.5 to 2 per epoxy group in the epoxy resin.

[0045] The adhesive component containing an epoxy resin and a phenolic resin may further contain a thermosetting resin other than the epoxy resin, or a curing agent other than the phenolic resin. Examples of the thermosetting resin other than the epoxy resin include polyimide resins, triazine resins such as melamine resins, and modified versions of these resins. Examples of the curing agent other than the phenolic resin include amines, amides, acid anhydrides, acids, and imidazoles.

[0046] In the wiring-forming member of this embodiment, the adhesive component may further contain a maleimide compound from the viewpoint of sufficiently suppressing the occurrence of bubbles or peeling during wiring formation.

[0047] In this case, from the viewpoint of sufficiently suppressing the occurrence of bubbles or peeling during wiring formation, the adhesive component may contain an epoxy resin as a thermosetting resin. In this case, the content of the epoxy resin in the adhesive component may be 5 to 95 mass %, 10 to 90 mass %, 15 to 85 mass %, or 15 to 40 mass % based on the total amount of the adhesive component (the total amount of solids other than the conductive particles in the adhesive layer 10).

[0048] The maleimide compound is a compound having at least one N-substituted maleimide group in one molecular structure. The maleimide compound may contain, for example, at least one selected from the group consisting of a polymaleimide compound (m1) (hereinafter sometimes referred to as "component (m1)") having at least two N-substituted maleimide groups in one molecular structure and derivatives thereof. Examples of "derivatives thereof" include an addition reaction product of the polymaleimide compound (m1) with an amine compound, such as a diamine compound, as described below. Because maleimide compounds have low reactivity, the inclusion of these compounds in adhesive component 14 is expected to result in a gradual curing reaction. The gradual curing reaction ensures sufficient flow time, making it possible to sufficiently suppress the occurrence of bubbles or peeling during wiring formation.

[0049] Examples of the component (m1) include N,N'-ethylene bismaleimide, N,N'-hexamethylene bismaleimide, N,N'-(1,3-phenylene) bismaleimide, N,N'-[1,3-(2-methylphenylene)] bismaleimide, N,N'-[1,3-(4-methylphenylene)] bismaleimide, N,N'-(1,4-phenylene) bismaleimide, bis(4-maleimidophenyl)methane, bis(3-methyl-4-maleimidophenyl)methane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethane bismaleimide, bis(4- maleimidophenyl) ether, bis(4-maleimidophenyl) sulfone, bis(4-maleimidophenyl) sulfide, bis(4-maleimidophenyl) ketone, bis(4-maleimidocyclohexyl)methane, 1,4-bis(4-maleimidophenyl)cyclohexane, 1,4-bis(maleimidomethyl)cyclohexane, 1,4-bis(maleimidomethyl)benzene, 1,3-bis(4-maleimidophenoxy)benzene, 1,3-bis(3-maleimidophenoxy)benzene, bis[4-(3-maleimidophenoxy)phenyl]methane, bis[ 4-(4-maleimidophenoxy)phenyl]methane, 1,1-bis[4-(3-maleimidophenoxy)phenyl]ethane, 1,1-bis[4-(4-maleimidophenoxy)phenyl]ethane, 1,2-bis[4-(3-maleimidophenoxy)phenyl]ethane, 1,2-bis[4-(4-maleimidophenoxy)phenyl]ethane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]buta 2,2-bis[4-(4-maleimidophenoxy)phenyl]butane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4-bis(3-maleimidophenoxy)biphenyl, 4,4-bis(4-maleimidophenoxy)biphenyl, bis[4-(3-maleimidophenoxy)phenyl]ketone, bis[4-(4-maleimidophenoxy)phenyl]ketone, 2,2-bis(4-maleimidophenyl)disulfide, bis(4-maleimidophenyl)disulfide, bis[4-(3-maleimidophenoxy)phenyl]sulfide, bis[4-(4-maleimidophenoxy)phenyl]sulfide, bis[4-(3-maleimidophenoxy)phenyl]sulfoxide, bis[4-(4-maleimidophenoxy)phenyl]sulfoxide, bis[4-(3-maleimidophenoxy)phenyl]sulfone, bis[4-(4-maleimidophenoxy)phenyl]sulfone, bis[4-(3-maleimidophenoxy)phenyl]ether, bis[4-(4-maleimidophenoxy)phenyl]ether, 1,4-bis[4-(4-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-maleimidophenoxy)-α,α -dimethylbenzyl]benzene, 1,4-bis[4-(3-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(4-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, and polyphenylmethane maleimide (for example, manufactured by Daiwa Kasei Co., Ltd., trade name: BMI-2300, etc.). The maleimide compounds may be used alone or in combination of two or more.

[0050] Among these maleimide compounds, bis(4-maleimidophenyl)methane, bis(4-maleimidophenyl)sulfone, N,N'-(1,3-phenylene)bismaleimide, 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, or polyphenylmethane maleimide are preferred, as they have a high reactivity and can provide higher heat resistance. In terms of solubility in solvents, bis(4-maleimidophenyl)methane is particularly preferred.

[0051] The maleimide compound may contain a derivative of polymaleimide compound (m1) from the viewpoints of solubility in organic solvents, compatibility, and adhesion to metal foils. The derivative of polymaleimide compound (m1) may contain, for example, a modified polymaleimide compound (M) having a structural unit derived from polymaleimide compound (m1) and a structural unit derived from amine compound (m2) having an amino group (hereinafter sometimes referred to as "component (m2)"). The modified polymaleimide compound (M) can also be considered an addition reaction product of component (m1) and component (m2). The structural unit derived from component (m1) and the structural unit derived from component (m2) contained in the modified polymaleimide compound (M) may each consist of one type or a combination of two or more types.

[0052] The modified polymaleimide compound (M) may be a compound having a structure represented by the following formula (1), which is formed by an addition reaction between a maleimide group in the component (m1) and an amino group in the component (m2): In formula (1), * indicates a bonding position.

[0053]

[0054] The component (m2) is preferably an amine compound (polyamine compound) having at least two amino groups, and may be a diamine compound having two amino groups. Examples of the component (m2) include 4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ketone, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4' -diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis(3-aminophenoxy)benzidine benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 1,3-bis[1-[4-(4-aminophenoxy)phenyl]-1-methylethyl]benzene, 1,4-bis[1-[4-(4-aminophenoxy)phenyl]-1-methylethyl]benzene, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bis Examples of the aromatic diamine compounds include aniline, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 3,3'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, and 9,9-bis(4-aminophenyl)fluorene; and amine compounds having a siloxane skeleton.

[0055] Among these, the component (m2) may be an amine compound having a siloxane skeleton from the viewpoint of low thermal expansion. That is, the modified polymaleimide compound (M) may have a structural unit derived from the polymaleimide compound (m1) and a structural unit derived from an amine compound having a siloxane skeleton.

[0056] The component (m2) may be a compound represented by the following general formula (2).

[0057]

[0058] In formula (2), X ｂ４ represents a divalent organic group.

[0059] From the viewpoint of low thermal expansion, the component (m2) is X in the above general formula (2). ｂ４ The component (m2) may contain an amine compound having a siloxane skeleton having a structural unit represented by the following general formula (3): ｂ４ may contain an amine compound having a siloxane skeleton having a structural unit (or group) represented by the following general formula (4).

[0060]

[0061] In formula (3), R ｂ１６ and R ｂ１７ each independently represents an alkyl group having 1 to 5 carbon atoms, a phenyl group, or a substituted phenyl group. * indicates the bonding position.

[0062]

[0063] In formula (4), R ｂ１６ and R ｂ１７ represents R in the general formula (3). ｂ１６ and R ｂ１７ and there are multiple R ｂ１６ and R ｂ１７ may be the same or different. ｂ１８ and R ｂ１９ each independently represents an alkyl group having 1 to 5 carbon atoms, a phenyl group, or a substituted phenyl group. ｂ９ and X ｂ１０ each independently represents a divalent organic group; n ｂ１３represents an integer of 2 to 100.

[0064] R ｂ１６ , R ｂ１７ , R ｂ１８ , and R ｂ１９ Examples of the substituent in the substituted phenyl group represented by the formula (I) include an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and an alkynyl group having 2 to 5 carbon atoms.

[0065] X ｂ９ and X ｂ１０ Examples of the divalent organic group represented by the formula (I) include an alkylene group, an alkenylene group, an alkynylene group, an arylene group, -O-, and a divalent linking group formed by combining these groups.

[0066] The content of the structural unit derived from the component (m1) in the modified polymaleimide compound (M) is not particularly limited, but may be 50 to 95% by mass, 70 to 92% by mass, or 75 to 90% by mass.

[0067] The content of the structural unit derived from the component (m2) in the modified polymaleimide compound (M) is not particularly limited, but may be 5 to 50 mass %, 8 to 30 mass %, or 10 to 25 mass %.

[0068] The total content of the structural units derived from the component (m1) and the structural units derived from the component (m2) in the modified polymaleimide compound (M) is not particularly limited, but may be 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass (i.e., consisting solely of structural units derived from the component (m1) and structural units derived from the component (m2)).

[0069] The content of the maleimide compound in the adhesive component may be 5 to 95 mass %, 10 to 90 mass %, or 15 to 85 mass %, based on the total amount of the adhesive component (the total amount of solids other than the conductive particles in the adhesive layer 10).

[0070] Examples of the curing accelerator include imidazole compounds, organic phosphorus compounds, tertiary amines, and quaternary ammonium salts. One type of curing accelerator may be used alone, or two or more types may be used in combination. The adhesive component may contain an imidazole compound as a curing accelerator, from the viewpoint of being able to arbitrarily adjust the temperature and time during use (for example, the heating temperature and heating time during thermocompression bonding).

[0071] The content of the curing accelerator in the adhesive component may be 0.001 to 10 mass % based on the total amount of the adhesive component.

[0072] The adhesive component 14 may contain other components in addition to the above-mentioned thermosetting component, such as a filler, an antioxidant, a film-forming material, a softener, an anti-aging agent, a colorant, a flame retardant, a thixotropic agent, and a coupling agent.

[0073] Examples of fillers include inorganic fillers and organic fillers. Examples of inorganic fillers include alumina, silica, titanium oxide, clay, calcium carbonate, aluminum carbonate, magnesium silicate, aluminum silicate, mica, short glass fiber, aluminum borate, and silicon carbide. Examples of organic fillers include silicone particles, methacrylate-butadiene-styrene particles, acrylic-silicone particles, polyamide particles, and polyimide particles. One type of filler may be used alone, or two or more types may be used in combination.

[0074] The adhesive component may contain silica particles as a filler from the viewpoints of improving heat resistance, improving mechanical properties, and adjusting flowability during use (for example, during thermocompression bonding).

[0075] The maximum diameter of the filler may be less than the particle diameter of the conductive particles 12, and may be 0.001 to 10 μm.

[0076] The content of the filler may be 5 to 60 parts by volume relative to 100 parts by volume of the adhesive component. When the content of the filler is 5 to 60 parts by volume, good connection reliability tends to be obtained.

[0077] Examples of antioxidants include quinone derivatives such as benzoquinone and hydroquinone, phenol derivatives (hindered phenol derivatives) such as 4-methoxyphenol and 4-t-butylcatechol, aminoxyl derivatives such as 2,2,6,6-tetramethylpiperidine-1-oxyl and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and hindered amine derivatives such as tetramethylpiperidyl methacrylate.

[0078] The content of the antioxidant may be 0.01% by mass to 5% by mass, or 0.1% by mass to 3% by mass, based on the total amount of the adhesive components.

[0079] Thermoplastic resins are preferably used as film-forming materials, including phenoxy resins, polyvinyl formal resins, polystyrene resins, polyvinyl butyral resins, polyester resins, polyamide resins, xylene resins, polyurethane resins, polyacrylic resins, and polyester urethane resins. Furthermore, these polymers may contain siloxane bonds or fluorine substituents. These resins may be used alone or in combination of two or more. Among the above resins, phenoxy resins may be used from the viewpoints of adhesive strength, compatibility, heat resistance, and mechanical strength.

[0080] The larger the molecular weight of the thermoplastic resin, the easier it is to obtain film-forming properties, and the melt viscosity, which affects the fluidity of the film, can be set within a wider range. The molecular weight of the thermoplastic resin may be 5,000 to 150,000, or 10,000 to 80,000, in terms of weight-average molecular weight. By setting the weight-average molecular weight to 5,000 or more, good film-forming properties are easily obtained, and by setting it to 150,000 or less, good compatibility with other components is easily obtained.

[0081] In this disclosure, the weight-average molecular weight refers to a value measured by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene under the following conditions: (Measurement conditions) Apparatus: GPC-8020 manufactured by Tosoh Corporation Detector: RI-8020 manufactured by Tosoh Corporation Column: Gelpack GLA160S + GLA150S manufactured by Resonaq Corporation Sample concentration: 120 mg / 3 mL Solvent: tetrahydrofuran Injection volume: 60 μL Pressure: 2.94 × 10 Pa (30 kgf / cm ２ ) Flow rate: 1.00mL / min

[0082] The content of the film-forming material may be 0.5 to 75% by mass, or 1 to 50% by mass, based on the total amount of the adhesive components.

[0083] From the viewpoint of improving storage stability and connection reliability, the adhesive component 14 may be substantially free of highly reactive radically polymerizable compounds such as acrylic compounds, methacrylic compounds, styrene compounds, and vinyl compounds. "Substantially free" means that the content of these compounds is 1% by mass or less, based on the total amount of the adhesive component. The content of these compounds in the adhesive component may be 0.5% by mass or less, or even 0% by mass, based on the total amount of the adhesive component.

[0084] From the viewpoint of forming a wiring layer that has sufficient crack resistance and excellent connectivity under high-temperature conditions, the adhesive layer 10 has a thermal expansion coefficient of 1.5 to 3% when heated from 40°C to 260°C. The thermal expansion coefficient can be determined by the following procedure. [Preparation of Cured Product] (1) As a pre-heating evaluation sample, a portion of the adhesive layer is scraped off and 0.60 g is weighed out. (2) A silicone sheet measuring 100 mm in length, 100 mm in width, and 1 mm in thickness is prepared, and a portion of this sheet is cut out to a size of 5 mm x 40 mm x 1 mm. (3) The pre-heating evaluation sample measured in (1) is placed in the cutout portion of the silicone sheet. (4) The silicone sheet containing the pre-heating evaluation sample is heated and pressurized using a thermocompression bonding device at 180°C and 2 MPa for 60 minutes to produce a cured pre-heating evaluation sample. [Measurement of thermal expansion coefficient of cured product] (1) The cured product of the pre-heated evaluation sample prepared above was cut into a size of 5 mm x 5 mm x 1 mm to prepare an evaluation sample. (2) Using a thermomechanical analyzer (TMA) (measurement mode: compression), the evaluation sample was heated from 40°C to 260°C at a heating rate of 5°C / min, the amount of change in thickness was measured, and the thermal expansion coefficient was calculated using the following formula: Thermal expansion coefficient (%) = (thickness at 260°C - thickness at 40°C) x 100 / (thickness at 40°C).

[0085] If the thermal expansion coefficient is 1.5% or more, it is easy to improve the crack resistance of the adhesive layer, and if the thermal expansion coefficient is 3% or less, the wiring layer can have excellent connectivity under high-humidity conditions. From the viewpoint of achieving a high level of both the crack resistance of the adhesive layer and good connectivity of the wiring layer under high-temperature conditions, the thermal expansion coefficient may be 1.6 to 2.9%, or 1.7 to 2.8%.

[0086] The thermal expansion coefficient can be adjusted, for example, by the following methods: (a) Methods for increasing the thermal expansion coefficient include increasing the amount of thermoplastic resin component, reducing the amount of filler, adding a low-elasticity component such as a rubber component or an elastomer component, reducing the amount of a component that crosslinks when cured, etc. (b) Methods for decreasing the thermal expansion coefficient include reducing the amount of thermoplastic resin component, increasing the amount of filler, reducing the amount of a low-elasticity component, increasing the amount of a component that crosslinks when cured, etc.

[0087] From the viewpoint of making it difficult for resistance unevenness to occur, the adhesive layer 10 may have a reaction rate of 90% or less, 85% or less, 80% or less, or 70% or less when heated at 180°C for 5 minutes.

[0088] The above-mentioned reactivity refers to a value determined by the following measurement method. [Measurement of reactivity after heating at 180°C for 5 minutes] A portion of the adhesive layer is scraped off to obtain two 5 mg pre-heating evaluation samples. Next, one of the pre-heating evaluation samples is heated at 180°C for 5 minutes to obtain a post-heating evaluation sample. For each of the pre-heating evaluation sample and the post-heating evaluation sample, the DSC calorific value is measured using a differential scanning calorimetry (DSC) device (product name DSC7, manufactured by Perkin Elmer) under a nitrogen gas flow at a measurement temperature range of 30°C to 250°C and a heating rate of 2°C / min. Based on the measured DSC calorific values, the reactivity after heating at 180°C for 5 minutes is determined using the following formula: Reactivity = (Cx - Cy) x 100 / Cx [where Cx represents the DSC calorific value (J / g) of the pre-heating evaluation sample, and Cy represents the DSC calorific value (J / g) of the post-heating evaluation sample.]

[0089] The reaction rate of the adhesive layer when heated at 180°C for 5 minutes can be reduced by, for example, adding the above-mentioned phenolic resin or maleimide compound, not adding a curing accelerator, or selecting a curing accelerator with a high reaction initiation temperature.

[0090] From the viewpoint of making it difficult for uneven resistance to occur, the ratio [Dp / T] of the average particle diameter Dp of the copper particles to the thickness T of the adhesive layer may be 0.56 to 1.2, 0.6 to 1.15, or 0.65 to 1.1.

[0091] The thickness of the adhesive layer may be 1 to 70 μm, 2 to 60 μm, or 3 to 50 μm.

[0092] [Configuration of Metal Layer] The surface roughness Rz of one surface of the metal layer 20 and the opposite surface may be the same or different. The metal layer 20 has a thickness of, for example, 5 μm to 200 μm. The thickness of the metal layer here refers to a thickness including the surface roughness Rz. The metal layer 20 is, for example, copper foil, aluminum foil, nickel foil, stainless steel, titanium, or platinum.

[0093] The adhesive layer 10 is disposed on the first surface 20a of the metal layer 20. The surface roughness Rz of the first surface 20a of the metal layer 20 may be 0.3 μm or more, 0.5 μm or more, or 1.0 μm or more. The surface roughness Rz of the first surface 20a of the metal layer 20 may be 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, less than 20 μm, 17 μm or less, 10 μm or less, 8.0 μm or less, 5.0 μm or less, or 3.0 μm or less. The surface roughness Rz of the first surface 20a of the metal layer 20 may be, for example, 0.3 μm or more and 20 μm or less, 0.3 μm or more and less than 20 μm, or more specifically, 0.5 μm or more and 10 μm or less. The surface roughness Rz of the second surface 20b of the metal layer 20 may be, for example, 20 μm or more, may be rougher than the surface roughness Rz of the first surface 20a, may be the same as the surface roughness of the first surface 20a, or may not be rougher than the surface roughness Rz of the first surface 20a. If the surface roughness Rz of the first surface 20a of the metal layer 20 is too smooth (for example, the surface roughness Rz is 0.2 μm), the adhesion between the metal layer 20 and the adhesive layer 10 may not be maintained over a long period of time, resulting in peeling. For this reason, the surface roughness Rz of the first surface 20a of the metal layer 20 may be 0.3 μm or more. However, by adopting a material or connection configuration that ensures adhesion, the surface roughness Rz of the first surface 20a of the metal layer 20 may be less than 0.3 μm.

[0094] The surface roughness Rz refers to the ten-point average roughness Rzjis measured in accordance with the method specified in the JIS standard (JIS B 0601-2001), and refers to a value measured using a commercially available surface roughness profile measuring instrument. For example, measurement can be performed using a nano search microscope ("SFT-3500" manufactured by Shimadzu Corporation).

[0095] Here, the relationship between the average particle diameter Dp of the conductive particles 12 and the surface roughness Rz of the first surface 20a of the metal layer 20 will be described below. In this embodiment, the "surface roughness / average particle diameter" which is the ratio of the surface roughness Rz of the first surface 20a of the metal layer 20 to the average particle diameter Dp of the conductive particles 12 may be 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.5 or more, or 1 or more. Furthermore, the "surface roughness / average particle diameter" which is the ratio of the surface roughness Rz of the first surface 20a of the metal layer 20 to the average particle diameter Dp of the conductive particles 12 may be 3 or less, 2 or less, 1.7 or less, or 1.5 or less. The "surface roughness / average particle size", which is the ratio of the surface roughness Rz of the first surface 20a of the metal layer 20 to the average particle size Dp of the conductive particles 12, may be, for example, 0.05 or more and 3 or less, and more specifically, 0.06 or more and 2 or less. In this embodiment, the surface roughness Rz of the first surface 20a of the metal layer 20 and the average particle size Dp of the conductive particles 12 may be controlled so that the "surface roughness / average particle size", which is the ratio of the surface roughness Rz of the first surface 20a of the metal layer 20 to the average particle size Dp of the conductive particles 12, is in the range of 0.05 to 3.

[0096] Another aspect of the present disclosure relates to a method for forming a wiring layer using a wiring-forming member. The method for forming a wiring layer using the above-described wiring-forming member 1 will be described with reference to Fig. 2. Fig. 2(a) to (d) are diagrams illustrating a method for forming a wiring layer using the wiring-forming member shown in Fig. 1.

[0097] First, as shown in Fig. 2(a), a wiring-forming member 1 is prepared. Furthermore, a base material 30 on which wiring 32 is formed is prepared. Then, the wiring-forming member 1 is placed so that the adhesive layer 10 side of the wiring-forming member 1 faces the base material 30. Thereafter, as shown in Fig. 2(b), lamination is performed so as to cover the wiring 32, and the wiring-forming member 1 is attached to the base material 30.

[0098] Next, as shown in FIG. 2C, the wiring-forming member 1 is heated and pressurized as desired, and is then pressed against the substrate 30. At this time, if the first surface 20a of the metal layer 20 of the wiring-forming member 1 is flat, the conductive particles 12, which must ensure electrical conductivity, can be more reliably deformed into flattened conductive particles 12a. In the pressed wiring-forming member 1a, the flattened conductive particles 12a (which destroy the insulating layer and expose the conductive portion) are arranged on the wiring 32, ensuring reliable electrical conduction between the metal layer 20 and the wiring 32. At this time, the adhesive layer 10 is also crushed, resulting in a thinner adhesive layer 10A.

[0099] 2(d), the metal layer 20 is subjected to a predetermined patterning process (e.g., etching process) to process it into a predetermined wiring pattern 20c (another wiring). At this time, the second surface 20b of the metal layer 20 may be processed to have a smooth surface. The above-described processes of FIGS. 2(a) to 2(d) may be repeated a predetermined number of times to form a wiring layer.

[0100] That is, the method for forming a wiring layer using a wiring forming member comprises the steps of preparing a wiring forming member, preparing a base material on which wiring is formed, placing the wiring forming member on the surface of the base material on which wiring is formed so that the adhesive layer side faces the substrate and covers the wiring, heating and pressing the wiring forming member to the base material, and performing a patterning process on the metal layer.

[0101] In this manner, a wiring-forming member 1b is formed. This wiring-forming member 1b includes a substrate 30 having wiring 32, and a cured product of adhesive component 14 of wiring-forming member 1 (adhesive layer of the thermocompression-bonded wiring-forming member) disposed on substrate 30 so as to cover wiring 32. In this wiring-forming member 1b, wiring 32 and metal layer 20 of wiring-forming member 1 or wiring 20c formed (e.g., by etching) from metal layer 20 are electrically connected by conductive particles 12a. Note that when the processes of (a) to (d) in FIG. 2 are repeated a predetermined number of times, wiring-forming member 1b may have a configuration including multiple wiring layers (layers connecting the above-mentioned wirings to each other).

[0102] As described above, according to the method for forming a wiring layer using the wiring formation member 1 of this embodiment, the process for forming a wiring layer that connects between wirings can be simplified compared to conventional processes that involve laser processing, fill plating, etc. Furthermore, the formed wiring layer can be easily thinned.

[0103] Furthermore, according to the method for forming a wiring layer using the wiring formation member 1 of this embodiment, when the adhesive layer 10 has the above-mentioned reaction rate and the ratio [Dp / T] of the average particle diameter Dp of the conductive particles 12 to the thickness T of the adhesive layer 10 is 0.56 to 1.2, a wiring layer with suppressed resistance unevenness can be formed.

[0104] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above embodiments and can be applied to various embodiments. For example, in the above embodiment, as shown in FIG. 3A, the conductive particles 12 are randomly or evenly dispersed within the adhesive layer 10 in the wiring-forming member 1. However, as shown in FIG. 3B, the conductive particles 12 may be arranged (distributed unevenly) on the metal layer 20 side. In this case, the conductive particles 12 are not exposed on the second surface 10b of the adhesive layer 10 opposite the metal layer 20, and the thickness of the adhesive layer 10 between the conductive particles 12 and the first surface 20a of the metal layer 20 may be greater than 0 μm or 0.1 μm and less than 1 μm. In this case, since the conductive particles 12 are arranged on the metal layer 20 side, the metal layer 20 can more reliably crush the conductive particles 12 into a flat shape in the wiring layer 1d. Furthermore, by distributing the conductive particles 12 unevenly on the metal layer 20 side in this manner, the capture rate of the conductive particles 12 on the wiring (electrode) or the like can be improved. That is, the conduction can be made more stable. Note that the distance between the conductive particles 12 and the first surface 20a of the metal layer 20 (the thickness of the adhesive layer 10 present therebetween) refers to the shortest distance from the surface of the metal layer 20 in contact with the adhesive layer 10 to the surface of the conductive particles 12, and is, for example, an average value at any 30 points. This distance is measured by sandwiching the wiring-forming member between two pieces of glass (thickness: approximately 1 mm) and casting it with a resin composition consisting of 100 g of bisphenol A-type epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of a curing agent (trade name: Epomount Curing Agent, manufactured by Refine Tech Co., Ltd.), polishing the cross section using a polishing machine, and then using a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-Tech Science Corporation).

[0105] Alternatively, as shown in FIG. 3C, the adhesive layer 10d may be formed separately into a first adhesive layer 10e and a second adhesive layer 10f. The adhesive components constituting the first adhesive layer 10e and the second adhesive layer 10f may be the same as those constituting the adhesive layer 10 described above, but the difference is that the second adhesive layer 10f does not contain conductive particles 12 dispersed therein. In this case, too, if the adhesive layer 10d has the above-described reactivity and the ratio [Dp / T] of the average particle diameter Dp of the conductive particles 12 to the thickness T of the adhesive layer 10 is 0.56 to 1.2, a wiring layer with reduced resistance unevenness can be formed. In the wiring-forming member 1e according to this modification, the conductive particles 12 are dispersed in the first adhesive layer 10e, i.e., are contained therein. In this case, as in the modification shown in FIG. 3B, the conductive particles 12 are arranged on the metal layer 20 side, which allows the metal layer 20 to more reliably flatten the conductive particles 12 in the wiring layer 1f. Furthermore, by distributing the conductive particles 12 unevenly on the metal layer 20 side in this manner, the capture rate of the conductive particles 12 in wiring (electrodes) or the like can be improved. In other words, the conduction can be made more stable.

[0106] The wiring-forming member 1, 1c, or 1e may further include a release film. The release film may be attached to the adhesive layer 10, 10c, or 10d on the side opposite to the side to which the metal layer 20 is attached, or may be attached to the side of the metal layer 20 opposite to the side to which the adhesive layer 10, 10c, or 10d is attached, or may be attached to both of these. Furthermore, the first surface 20a of the metal layer 20 may be attached to the adhesive layer 10, 10c, or 10d. In this case, the wiring-forming member becomes easier to handle, and the work efficiency when forming a wiring layer using the wiring-forming member can be improved.

[0107] Furthermore, although the above description has been given taking as an example a case where the wiring-forming member is a member formed by bonding the adhesive layer 10 and the metal layer 20, the wiring-forming member in this embodiment may be configured as a set product in which the adhesive layer 10 and the metal layer 20 are provided as separate bodies and, during use, the adhesive layer 10 can be bonded to the first surface 20a of the metal layer 20. In this case, since the adhesive layer 10 and the metal layer 20 can be prepared separately (as a set of wiring-forming members), it becomes possible to improve the degree of freedom in the work when fabricating a wiring layer using the wiring-forming member, such as by selecting a wiring-forming member with a more optimal material composition.

[0108] The adhesive film with a metal layer of this embodiment may have an adhesive layer including a first adhesive layer containing copper particles and an adhesive component, and a second adhesive layer containing an adhesive component. Such an adhesive film with a metal layer can also be used to form wiring. Details of the adhesive film with a metal layer having the above configuration will be described below, taking as an example a case where it is used as a wiring-forming member.

[0109] Fig. 4 is a cross-sectional view showing a wiring-forming member according to another embodiment of the present disclosure. The wiring-forming member 2 shown in Fig. 4 is configured to include an adhesive layer 10 containing conductive particles 12 and a metal layer 20. The adhesive layer 10 includes a first adhesive layer 15 containing conductive particles 12 and an adhesive component 14, and a second adhesive layer 16 containing an adhesive component 17.

[0110] The first adhesive layer 15 contains conductive particles 12 and an insulating adhesive component 14 in which the conductive particles 12 are dispersed. The adhesive component 14 is the same as that described above.

[0111] The second adhesive layer 16 includes an insulating adhesive component 17. The insulating adhesive component 17 in the second adhesive layer 16 may be the same as or different from the adhesive component 14. The adhesive component 17 in the second adhesive layer 16 is defined as a solid content other than conductive particles. The second adhesive layer 16 may be in a B-stage state, i.e., a semi-cured state, before the wiring layer is formed using the wiring-forming member 2.

[0112] In this embodiment, the reactivity of the first adhesive layer 15 and the second adhesive layer 16 is adjusted so that the adhesive layer 10 has the above-mentioned reaction rate, and the average particle size of the conductive particles 12 and the thicknesses of the first adhesive layer 15 and the second adhesive layer 16 may be adjusted so that the ratio [Dp / T] of the average particle size Dp of the conductive particles 12 to the thickness T of the adhesive layer 10 is within the above-mentioned range.

[0113] The thickness d1 of the first adhesive layer 15 may be 0.56 to 1.2 times, 0.56 to 1.0 times, or 0.56 to 0.80 times the average particle diameter Dp of the conductive particles 12.

[0114] The thickness of the first adhesive layer 15 may be 1 to 70 μm, 1 to 60 μm, or 1 to 50 μm.

[0115] The thickness of the second adhesive layer 16 may be 0 to 50 μm, 0 to 40 μm, or 0 to 30 μm.

[0116] Next, a method for forming a wiring layer using the above-described wiring-forming member 2 will be described with reference to Fig. 5. Fig. 5(a) to (d) are diagrams illustrating a method for forming a wiring layer using the wiring-forming member shown in Fig. 4.

[0117] First, as shown in Fig. 5(a), a wiring-forming member 2 is prepared. Furthermore, a base material 30 on which wiring 32 is formed is prepared. Then, the wiring-forming member 2 is placed so that the adhesive layer 10 side of the wiring-forming member 2 faces the base material 30. Thereafter, as shown in Fig. 5(b), lamination is performed so as to cover the wiring 32, and the wiring-forming member 2 is attached to the base material 30.

[0118] Next, as shown in FIG. 5C, the wiring-forming member 2 is heated and pressurized as desired, and is then pressed against the substrate 30. If the first surface 20a of the metal layer 20 of the wiring-forming member 2 is flat, the conductive particles 12, which must be electrically conductive, can be more reliably deformed into flattened conductive particles 12a. In the pressed wiring-forming member 2a, the flattened conductive particles 12a (which destroy the insulating layer and expose the conductive portion) are arranged on the wiring 32, ensuring good electrical conduction between the metal layer 20 and the wiring 32. At this time, the adhesive layer 10 is also crushed, resulting in a thinner adhesive layer 10B. Furthermore, because the adhesive layer 10 includes a first adhesive layer 15 containing conductive particles in its adhesive components and a second adhesive layer 16, good insulation reliability is achieved in the thickness direction in areas where electrical connection is not desired.

[0119] 5(d), the metal layer 20 is subjected to a predetermined patterning process (e.g., etching process) to process it into a predetermined wiring pattern 20c (another wiring). At this time, the second surface 20b of the metal layer 20 may be processed to have a smooth surface. The above-described processes of FIGS. 5(a) to 5(d) may be repeated a predetermined number of times to form a wiring layer.

[0120] That is, the method for forming a wiring layer using a wiring forming member comprises the steps of preparing a wiring forming member, preparing a base material on which wiring is formed, placing the wiring forming member on the surface of the base material on which wiring is formed so that the adhesive layer side faces the substrate and covers the wiring, heating and pressing the wiring forming member to the base material, and performing a patterning process on the metal layer.

[0121] In this manner, the wiring-forming member 2b is formed. The wiring-forming member 2b includes a substrate 30 having wiring 32, and a cured product (adhesive layer of the wiring-forming member bonded by heating and pressure) of the first adhesive layer 15 and the second adhesive layer 16 of the wiring-forming member 2, which is disposed on the substrate 30 so as to cover the wiring 32. In the wiring-forming member 2b, the wiring 32 and the metal layer 20 of the wiring-forming member 2 or the wiring pattern 20c formed (e.g., by etching) from the metal layer 20 are electrically connected by the conductive particles 12a. Note that when the processes of (a) to (d) in FIG. 5 are repeated a predetermined number of times, the wiring-forming member 2b may have a configuration including multiple wiring layers (layers connecting the above-mentioned wirings to each other).

[0122] As described above, according to the method for forming a wiring layer using the wiring formation member 2 of this embodiment, the process for forming a wiring layer that connects between wirings can be simplified compared to conventional processes that involve laser processing, fill plating, etc. Furthermore, the formed wiring layer can be easily thinned.

[0123] Furthermore, according to the method for forming a wiring layer using the wiring formation member 2 of this embodiment, when the adhesive layer 10 has the above-mentioned reaction rate and the ratio [Dp / T] of the average particle diameter Dp of the conductive particles 12 to the thickness T of the adhesive layer 10 is 0.56 to 1.2, a wiring layer with suppressed resistance unevenness can be formed.

[0124] Furthermore, the method for forming a wiring layer using the wiring-forming member 2 according to this embodiment has the following effects, ensuring sufficient freedom in the design of the wiring pattern when forming the wiring layer. (i) By including the second adhesive layer 16 in the adhesive layer 10, even if the wiring layer formed by patterning the metal layer 20 has portions in the stacking direction (or the thickness direction of the adhesive layer) where conductive connection is not desired, it becomes easy to ensure insulation reliability in those portions. (ii) In the wiring layer formed by patterning the metal layer 20 or in the separately formed rewiring, the conductive particles 12 are less likely to come into contact with portions other than the portions to be conductively connected, making it easy to suppress electrical transmission loss in the wiring due to contact of the conductive particles.

[0125] The above effects will be described with reference to the drawings.

[0126] 6A and 6B are cross-sectional views for explaining an example of a case where a wiring layer is formed using the wiring forming member 2 according to this embodiment.

[0127] 6(a) shows a state in which a substrate 30 having wiring patterns 32a and 32b is prepared, and a wiring-forming member 2 is placed on the surface of the substrate 30 on which the wiring patterns are formed so that the adhesive layer 10 side faces the substrate 30, covering the wiring patterns 32a and 32b. After this, a step of thermocompression bonding the wiring-forming member 2 to the substrate 30 and a step of patterning the metal layer 20 are performed, thereby obtaining a wiring-forming member formed with a wiring pattern 20d that is electrically connected to the wiring pattern 32a and a wiring pattern 20e that is not intended to be electrically connected to the wiring pattern 32b, as shown in FIG.

[0128] Here, adhesive layer 10 of wiring formation member 2 includes first adhesive layer 15 containing conductive particles 12 and adhesive component 14, and second adhesive layer 16 containing no conductive particles but adhesive component 17, so that when pressure-bonded, good conduction between wiring pattern 20d and wiring pattern 32a is ensured via conductive particles 12, while adhesive layer 18a can be provided with a thickness that ensures a distance between wiring pattern 20e and wiring pattern 32b, which are not intended to be electrically connected, that prevents conduction through conductive particles 12. This prevents conductive connection between wiring pattern 20e and wiring pattern 32b, ensuring insulation reliability in the thickness direction of the adhesive layer.

[0129] 7A and 7B are cross-sectional views for explaining another example in which a wiring layer is formed using the wiring forming member 2 according to this embodiment.

[0130] 7A shows a state in which a substrate 30 having a wiring pattern 32a is prepared, and a wiring-forming member 2 is placed on the surface of the substrate 30 on which the wiring pattern is formed so that the adhesive layer 10 side faces the substrate 30 to cover the wiring pattern 32a. After this, a step of thermocompression bonding the wiring-forming member 2 to the substrate 30 and a step of patterning the metal layer 20 are performed, thereby obtaining a wiring-forming member formed with a wiring pattern 20d that is conductively connected to the wiring pattern 32a and a wiring pattern 20f that is not conductively connected (or a portion of the wiring pattern that is not conductively connected), as shown in FIG.

[0131] Here, the adhesive layer 10 of the wiring forming member 2 includes a first adhesive layer 15 containing conductive particles 12 and adhesive component 14, and a second adhesive layer 16 containing no conductive particles but adhesive component 17. This allows for the provision of an adhesive layer 18a that, when pressed together, ensures good electrical conduction between the wiring pattern 20d and the wiring pattern 32a via the conductive particles 12 while preventing contact between the wiring pattern 20f and the conductive particles 12. This reduces electrical transmission loss in the wiring pattern 20f due to contact between the conductive particles. In particular, the wiring forming member 2 includes the metal layer 20, the second adhesive layer 16, and the first adhesive layer 15 stacked in this order, making it easy to prevent contact between the wiring pattern 20f and the conductive particles 12.

[0132] In the method shown in FIG. 7, the wiring pattern 20f may be formed by a step of patterning the metal layer 20 and a step of forming rewiring.

[0133] In the first adhesive layer 15 of the wiring forming member 2 shown in Figure 4, the conductive particles 12 are arranged locally, but the conductive particles 12 may also be dispersed randomly or evenly within the adhesive component 14.

[0134] In addition, in the first adhesive layer 15 of the wiring forming member 2, the conductive particles 12 may be locally arranged on the second adhesive layer 16 side, or the conductive particles 12 may be locally arranged on the opposite side to the second adhesive layer 16 side (the second surface 10b side of the adhesive layer 10).

[0135] Furthermore, although the second adhesive layer 16 of the wiring forming member 2 does not contain conductive particles, the second adhesive layer 16 may contain a portion of the particle body of the conductive particle 12 (in other words, it may not contain the entire particle body of the conductive particle 12).

[0136] Furthermore, the adhesive layer 10 of the wiring formation member 2 may be composed of two layers, a first adhesive layer 15 and a second adhesive layer 16, or may be composed of three or more layers including a layer other than the first adhesive layer 15 and the second adhesive layer 16 (for example, a third adhesive layer). The third adhesive layer may be a layer having the same composition as that described above for the first adhesive layer 15 or the second adhesive layer 16, and may be a layer having the same thickness as that described above for the first adhesive layer 15 or the second adhesive layer 16. For example, the wiring formation member 2 may be composed by laminating a metal layer, a third adhesive layer, a second adhesive layer, and a first adhesive layer in this order, or may be composed by laminating a metal layer, a second adhesive layer, a first adhesive layer, and a third adhesive layer in this order, but is not limited thereto.

[0137] The wiring-forming member 2 may further include a release film. The release film may be attached to the side of the adhesive layer 10 opposite to the side to which the metal layer 20 is bonded (the second surface 10b side of the adhesive layer 10), or may be attached to the side of the metal layer 20 opposite to the side to which the adhesive layer 10 is bonded (the first surface 20a of the metal layer) (the second surface 20b side of the metal layer 20), or may be attached to both of these. In this case, the wiring-forming member becomes easier to handle, and the work efficiency when forming a wiring layer using the wiring-forming member can be improved.

[0138] Furthermore, although the above description has been given taking as an example a case where the wiring-forming member is a member formed by bonding the adhesive layer 10 and the metal layer 20, the wiring-forming member 2 in this embodiment may be configured as a set product in which the adhesive layer 10 and the metal layer 20 are provided as separate bodies and, during use, the adhesive layer 10 can be bonded to the first surface 20a of the metal layer 20. In this case, since the adhesive layer 10 and the metal layer 20 can be prepared separately (as a set of wiring-forming members), it becomes possible to improve the degree of freedom in the work when fabricating a wiring layer using the wiring-forming member, such as by selecting a wiring-forming member with a more optimal material composition.

[0139] An adhesive film according to one embodiment of the present disclosure contains conductive particles and a thermosetting resin composition, and has a thermal expansion coefficient of 1.5 to 3% when a cured product of the adhesive film is heated from 40° C. to 260° C. The cured product of the adhesive film can be prepared in the same manner as the cured product of the adhesive layer described above, and the thermal expansion coefficient can be measured in the same manner.

[0140] The adhesive film according to this embodiment may have the same configuration as the adhesive layer in the wiring formation member described above.

[0141] The adhesive film according to this embodiment can be produced by the following method. Specifically, first, a thermosetting resin composition and conductive particles are added to a solvent (organic solvent), and dissolved or dispersed by stirring, mixing, kneading, or the like to prepare a varnish composition (varnish-like adhesive composition). The varnish composition is then applied to a release-treated substrate using a knife coater, roll coater, applicator, comma coater, die coater, or the like, and the solvent is then volatilized by heating to form an adhesive film on the substrate.

[0142] The solvent used in preparing the varnish composition may be a solvent capable of uniformly dissolving or dispersing each component. Examples of such solvents include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and butyl acetate. These solvents can be used alone or in combination of two or more. The stirring, mixing, and kneading in preparing the varnish composition can be performed using, for example, a mixer, a grinder, a three-roll mill, a ball mill, a bead mill, or a homodisper.

[0143] The substrate is not particularly limited as long as it has heat resistance sufficient to withstand the heating conditions when volatilizing the solvent, and for example, substrates (e.g., films) made of oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymer, etc. can be used.

[0144] The adhesive film according to this embodiment can be used to connect circuit components, and can be suitably used as an adhesive film for circuit connection for connecting a first circuit component having a first electrode (e.g., a first circuit component having a first circuit electrode formed on the main surface of a first substrate) to a second circuit component having a second electrode (e.g., a second circuit component having a second circuit electrode formed on the main surface of a second substrate) with the first electrode and the second electrode (the first circuit electrode and the second circuit electrode) arranged opposite each other. The adhesive film according to this embodiment can improve the conductivity between electrodes in a circuit connection structure.

[0145] Examples of the first circuit member and the second circuit member include chip components such as semiconductor chips, resistor chips, and capacitor chips, and substrates such as printed circuit boards.

[0146] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to these examples.

[0147] <Preparation of Adhesive Component (Thermosetting Resin Composition)> The following thermosetting component and filler were prepared as adhesive components. (Thermosetting Components) Epoxy resin A: NC-3000H (biphenylaralkyl type epoxy resin, trade name, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 289 g / eq) Epoxy resin B: YL983U (bisphenol F type epoxy resin, trade name, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 170 g / eq) Epoxy resin C: HP-4700 (naphthalene type multifunctional epoxy resin, trade name, manufactured by DIC Corporation, epoxy equivalent: 165 g / eq) Epoxy resin D: jER-630 (multifunctional epoxy resin, trade name, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 98 g / eq) Phenolic resin A: KA-1160 (cresol novolac type phenolic resin, trade name, manufactured by DIC Corporation, hydroxyl equivalent: 117 g / eq) The hydroxyl equivalent of the phenolic resin was determined by the following measurement method. Phenolic resin B: KA-1163 (cresol novolac phenolic resin, trade name, manufactured by DIC Corporation, hydroxyl equivalent: 118 g / eq). The hydroxyl equivalent of the phenolic resin was determined by the following measurement method. Phenolic resin C: KA-1165 (cresol novolac phenolic resin, trade name, manufactured by DIC Corporation, hydroxyl equivalent: 119 g / eq). The hydroxyl equivalent of the phenolic resin was determined by the following measurement method. Phenoxy resin A: YP-70 (BPA / BPF copolymer, trade name, manufactured by Nippon Steel Chemical & Material Co., Ltd.) Curing accelerator A: G-8009L (isocyanate mask imidazole, trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) (Filler) Silica particles A: SC-2050KC (phenylaminosilane-treated silica filler, average particle size 0.5 μm, manufactured by Admatechs Co., Ltd.)

[0148] <Method for Measuring Hydroxyl Equivalent> 1 g of sample was precisely weighed into a round-bottom flask, and 5 mL of acetic anhydride and pyridine test solution were accurately weighed. Next, an air condenser was attached to the flask, and the flask was heated at 100°C for 1 hour. After cooling the flask, 1 mL of water was added, and the flask was again heated at 100°C for 10 minutes. After re-cooling the flask, the air condenser and the neck of the flask were rinsed with 5 mL of neutralized methanol, and 1 mL of phenolphthalein reagent was added. The resulting solution was titrated with a 0.1 mol / L potassium hydroxide-ethanol solution to determine the hydroxyl value. From the obtained hydroxyl value, the hydroxyl equivalent (g / eq), converted to the mass per 1 mol (1 eq) of hydroxyl groups, was calculated.

[0149] <Preparation of Conductive Particles> The following conductive particles were prepared. (Conductive Particles 1) Cu particles (manufactured by Mitsui Mining & Smelting Co., Ltd., product name "MA-CJU", average particle size 20 μm, specific gravity 8.9) were prepared as conductive particles 1. (Conductive Particles 2) Cu particles (manufactured by Mitsui Mining & Smelting Co., Ltd., product name "MA-CKU", average particle size 10 μm, specific gravity 8.9) were prepared as conductive particles 2.

[0150] <Physical Properties of Conductive Particles> The change and recovery when a pressure of 50 mN was applied per particle were measured by a microcompression test using a probe under the following conditions. Measuring device: "FISCHERSCOPE HM2000" (manufactured by Fisher Instruments) Probe size (area): 100 μm × 100 μm Compression time: 50 seconds of compression / 50 seconds of return Measurement temperature: 25°C Thrust force: 50 mN The change and recovery of conductive particle 1 were 3.39 μm and 0.15 μm, respectively. The change and recovery of conductive particle 2 were 4.86 μm and 0.13 μm, respectively.

[0151] <Preparation of wiring forming member> (Example 1) 5.00 g of epoxy resin A, 4.69 g of epoxy resin B, 4.08 g of phenol resin B, 2.68 g of phenoxy resin A, and 0.025 g of curing accelerator A were dissolved in 19.1 g of methyl ethyl ketone (MEK), and then 5.36 g of silica particles A and 4.21 g of conductive particles 1 were added to prepare a coating liquid for forming an adhesive layer.

[0152] This coating solution was applied to one side (surface roughness Rz: 3.0 μm) of copper foil (manufactured by Mitsui Mining & Smelting, product name "3EC-M3-VLP", thickness: 12 μm) using a coating device (manufactured by Yasui Seiki Co., Ltd., product name: Precision Coater), and the resultant was dried with hot air at 70°C for 5 minutes, thereby providing an adhesive layer with a thickness of 25 μm on the copper foil. In this way, the wiring-forming member of Example 1 was produced.

[0153] (Examples 2 to 11, Comparative Examples 1 to 3) Each wiring-forming member was produced in the same manner as in Example 1, except that an adhesive layer-forming coating solution was prepared with the composition and blending amount shown in Table 1 or Table 2, and an adhesive layer was formed with the thickness shown in Table 1 or Table 2.

[0154] [Coefficient of thermal expansion when the cured product of the adhesive layer is heated from 40°C to 260°C] The coefficient of thermal expansion of the cured product of the adhesive layer was measured using the following procedure. [Preparation of cured product] (1) A portion of the adhesive layer was scraped off and 0.60 g was weighed out as a pre-heating evaluation sample. (2) A silicone sheet measuring 100 mm in length, 100 mm in width, and 1 mm in thickness was prepared, and a portion of this sheet was cut out to a size of 5 mm x 40 mm x 1 mm. (3) The pre-heating evaluation sample measured in (1) was placed in the cutout portion of the silicone sheet. (4) The silicone sheet containing the pre-heating evaluation sample was heated and pressurized using a thermocompression bonding device at 180°C and 2 MPa for 60 minutes to prepare a cured product of the pre-heating evaluation sample. [Measurement of coefficient of thermal expansion of cured product] (1) The cured product of the pre-heating evaluation sample prepared above was cut into a size of 5 mm x 5 mm x 1 mm to prepare an evaluation sample. (2) Using a thermomechanical analyzer (TMA) (measurement mode: compression), the thickness change amount when the evaluation sample is heated from 40°C to 260°C at a temperature increase rate of 5°C / min is measured, and the thermal expansion coefficient is calculated using the following formula: Thermal expansion coefficient (%) = (thickness at 260°C - thickness at 40°C) x 100 / (thickness at 40°C).

[0155] [Measurement of Reaction Rate When Heated at 180°C for 5 Minutes] The reaction rate of the adhesive layer prepared above when heated at 180°C for 5 minutes was determined according to the following method. A portion of the adhesive layer was scraped off to obtain two 5 mg pre-heating evaluation samples. Next, one of the pre-heating evaluation samples was heated at 180°C for 5 minutes to obtain a post-heating evaluation sample. For each of the pre-heating evaluation sample and the post-heating evaluation sample, the DSC calorific value was measured using a differential scanning calorimetry (DSC) device (product name DSC7, manufactured by Perkin Elmer) under a nitrogen gas flow at a measurement temperature range of 30°C to 250°C and a heating rate of 10°C / min. Based on the measured DSC calorific value, the reaction rate when heated at 180°C for 5 minutes was calculated using the following formula. Reaction rate = (Cx - Cy) x 100 / Cx (where Cx represents the DSC calorific value (J / g) of the evaluation sample before heating, and Cy represents the DSC calorific value (J / g) of the evaluation sample after heating).

[0156] [Evaluation of Wiring Forming Member] Evaluation samples of the wiring forming members prepared above were prepared according to the following method, and their connection resistance values ​​were measured. The connection resistance values ​​were evaluated according to the following criteria.

[0157] [Measurement of Connection Resistance Value] <Preparation of Evaluation Sample> The wiring-forming member was attached to a printed wiring board (PWB) having three copper circuits, each 15 μm thick and with a line width of 1000 μm and a pitch of 10000 μm, on a glass cloth-reinforced epoxy substrate. This was connected over a width of 2 mm by heating and pressurizing at 180° C. and 2 MPa for 60 minutes using a thermocompression bonding device (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.), to prepare a connection.

[0158] The prepared connectors with resist formed on them were immersed in an etching solution and swung. The etching solution was prepared with 100 g / L copper chloride and 100 ml / L hydrochloric acid. When the desired copper foil area was gone, the connectors were washed with pure water. The resist was then peeled off to obtain the desired evaluation samples.

[0159] <Evaluation of Evaluation Sample (Initial)> The resistance between the remaining copper foil on the circuit and the copper circuit on the substrate was measured with a multimeter immediately after bonding. The connection resistance was calculated as the average of 37 resistance points between the remaining copper foil on the circuit and the copper circuit on the substrate, and evaluated according to the following criteria.

[0160] [Judgment criteria for connection resistance] A: The average resistance value is 5 mΩ or less. B: The average resistance value is more than 5 mΩ and 10 mΩ or less. C: The average resistance value is more than 10 mΩ.

[0161] <Evaluation of Evaluation Samples (After Reflow Test)> The evaluation samples were subjected to a reflow process having the following temperature profile three times, and then the connection resistance was measured in the same manner as above and evaluated according to the criteria above. Temperature profile: heated from 50°C to 150°C at a temperature increase rate of 2°C / sec, held at 150°C for 100 seconds, heated from 150°C to 245°C at a temperature increase rate of 1°C / sec, held at 245°C for 50 seconds, and then allowed to cool from 245°C to 40°C.

[0162] [Mandrel Test] A mandrel test was carried out on the members for forming wiring fabricated in the examples and comparative examples in accordance with JIS K5600-5-1.

[0163]

[0164]

[0165] 1, 1a, 1c, 1e...wiring forming member, 1d, 1f...wiring layer, 1b...wiring forming member, 2...wiring forming member, 10, 10c, 10d, 10A, 10B...adhesive layer, 10a...first surface, 10b...second surface, 10e...first adhesive layer, 10f...second adhesive layer, 12, 12a...conductive particles, 14...adhesive component, 15...first adhesive layer, 16...second adhesive layer, 17...adhesive component, 20...metal layer, 20a...first surface, 20b...second surface, 30...substrate, 32...wiring.

Claims

1. An adhesive film containing conductive particles and a thermosetting resin composition, wherein the adhesive film has a thermal expansion coefficient of 1.5 to 3% when the cured adhesive film is heated from 40°C to 260°C.

2. The adhesive film according to claim 1, which has a reaction rate of 90% or less when heated at 180°C for 5 minutes.

3. The adhesive film of claim 1, wherein the conductive particles comprise copper particles.

4. An adhesive film with a metal layer, comprising a metal layer and an adhesive layer disposed on the metal layer, the adhesive layer containing conductive particles and a thermosetting resin composition, and the cured product of the adhesive layer having a thermal expansion coefficient of 1.5 to 3% when heated from 40°C to 260°C.

5. The adhesive film with a metal layer according to claim 4, wherein the adhesive layer has a reaction rate of 90% or less when heated at 180°C for 5 minutes.

6. The adhesive film with a metal layer according to claim 4, wherein the conductive particles include copper particles.

7. The adhesive film with a metal layer according to claim 4 or 5, which is used to form wiring.

8. A wiring-forming member, comprising an adhesive layer and a metal layer provided as separate bodies, the adhesive layer being capable of adhering to the metal layer during use, the adhesive layer comprising conductive particles and a thermosetting resin composition, and a coefficient of thermal expansion of the cured adhesive layer when heated from 40°C to 260°C of 1.5 to 3%.

9. The member for forming wiring according to claim 8, wherein the adhesive layer has a reaction rate of 90% or less when heated at 180° C. for 5 minutes.

10. The wiring forming member according to claim 8, wherein the conductive particles include copper particles.

11. A method for forming a wiring layer, comprising the steps of: preparing an adhesive film with a metal layer according to any one of claims 4 to 6; preparing a substrate on which wiring is formed; placing the adhesive film with a metal layer on the surface of the substrate on which wiring is formed so as to cover the wiring, with the adhesive layer facing the substrate; heat-pressing the adhesive film with a metal layer to the substrate; and performing a patterning process on the metal layer.

12. A method for forming a wiring layer, comprising the steps of: preparing a wiring formation member according to any one of claims 8 to 10; preparing a substrate on which wiring is formed; placing the wiring formation member on the surface of the substrate on which wiring is formed so as to cover the wiring, with the adhesive layer facing the substrate; thermocompressing the wiring formation member to the substrate; and performing a patterning process on the metal layer.

13. A wiring-forming member comprising: a substrate having wiring; and a cured product of the adhesive layer of a metal layer-attached adhesive film according to any one of claims 4 to 6, which is disposed on the substrate so as to cover the wiring, wherein the wiring is electrically connected to the metal layer of the metal layer-attached adhesive film or to another wiring formed from the metal layer.

14. A wiring-forming member comprising: a substrate having wiring; and a cured product of the adhesive layer of the wiring-forming member according to any one of claims 8 to 10, which is disposed on the substrate so as to cover the wiring, wherein the wiring is electrically connected to the metal layer of the wiring-forming member or to another wiring formed from the metal layer.

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