CN118098676A - Roll-type conductive bonding sheet, wiring board with metal reinforcing plate, and electronic device - Google Patents

Abstract

The present disclosure provides a rolled conductive bonding sheet, a wiring board with a metal reinforcing plate, and an electronic device, wherein no blocking occurs during rolling, the film thickness guarantee is excellent, the peeling property of the protective sheet is good, and the lamination strength and the adhesion are high. The present disclosure is a roll-shaped conductive bonding sheet obtained by winding a conductive bonding sheet into a roll, wherein the conductive bonding sheet has a protective sheet and a conductive bonding agent layer, the conductive bonding agent layer has a probe tack adhesion of 5.0N/cm ² or less, and the conductive bonding agent layer has a highest value of storage elastic modulus of 1.0X10 ⁷Pa～2.0×10⁹ Pa at 25 to 30 ℃.

Description

Rolled conductive bonding sheet, wiring board with metal reinforcement plate, and electronic device

Technical Field

The present disclosure relates to a rolled conductive bonding sheet, a wiring board with a metal reinforcing plate, and an electronic device.

Background Art

The flexible printed wiring board mounted inside the electronic device has flexibility. From the perspective of configuring an electromagnetic wave shielding layer and connecting the components such as a connector, it is known that there is a structure in which a reinforcing plate is configured to suppress deformation. In the past, epoxy glass and the like were used as reinforcing plates, but from the perspective of imparting the function of suppressing electromagnetic wave noise, a metal plate is used. A conductive adhesive having a resin as the main component is used to connect the shielding layer or the metal plate to the flexible printed wiring board.

For example, in International Publication No. 2016/002780, a conductive adhesive composition having a polyurethane polyurea resin, an epoxy resin, and a conductive filler is disclosed as a conductive adhesive for bonding a conductive reinforcing plate (metal plate) disposed opposite to a grounding wiring pattern (wiring board). In addition, in International Publication No. 2019/031394, a conductive adhesive is disclosed, which adds an organic salt, talc, carbon black, and silica as a loss modulus modifier, thereby improving embedding and adhesion.

Summary of the invention

[Problems to be solved by the invention]

Generally, a conductive adhesive sheet is wound into a roll (reel) with a conductive adhesive layer laminated on a protective sheet. However, when the conductive adhesive layer is unrolled from the roll, so-called blocking occurs, which is a problem.

In addition, when the sample is rolled into a roll, tension is applied to prevent the roll from collapsing. However, if the winding tension is strong, the following problem occurs: the thickness (film thickness) of the conductive adhesive layer is reduced (film thickness guarantee) due to long-term storage under a state where the conductive adhesive layer is subjected to strong pressure.

Furthermore, after the conductive bonding sheet is temporarily bonded to an adherend such as a metal plate by thermocompression bonding, the protective sheet is deformed or damaged when being peeled off, and a problem of being unable to be peeled off (peelability of the protective sheet) occurs.

In addition, if the softening of the conductive adhesive layer is insufficient during the temporary bonding, the following problems may arise: the adhesion of the conductive adhesive layer to the metal plate may become insufficient, and the conductive adhesive layer may peel off from the metal plate during the process of processing the metal reinforcement plate formed by laminating the conductive adhesive layer and the metal plate into the desired shape, i.e., the so-called punching process (lamination strength).

In addition, when the laminate of the metal plate/conductive adhesive layer/wiring board is heated and pressed (hot pressing) at a specified temperature (for example, 170°C) and then a tensile force is applied to the protective sheet, if the elastic modulus of the conductive adhesive layer near room temperature is very high, a problem of cohesive failure and easy peeling will occur (adhesion).

[Technical means to solve the problem]

The present inventors have conducted extensive studies and have found that the problems of the present disclosure can be solved in the following aspects, thereby completing the present disclosure.

[1] A rolled conductive bonding sheet, wherein the conductive bonding sheet is wound into a roll, wherein the conductive bonding sheet comprises a protective sheet and a conductive bonding layer, the probe tack adhesion of the conductive bonding layer is 5.0 N/ ^cm2 or less, and the maximum value of the storage elastic modulus of the conductive bonding layer at 25°C to 30°C is 1.0× ¹⁰⁷ Pa to 2.0× ¹⁰⁹ Pa.

[2]: The rolled conductive bonding sheet according to [1], wherein the conductive bonding agent layer has a maximum storage elastic modulus of 3.0×10 ⁶ Pa to 1.5×10 ⁸ Pa at 70° C. to 120° C.

[3]: The rolled conductive bonding sheet according to [2], wherein the maximum value of the storage elastic modulus of the protective sheet at 25°C to 30°C is 1.0×10 ⁹ Pa or more.

[4]: The rolled conductive bonding sheet according to any one of [1] to [3], wherein the conductive bonding agent layer has one or more selected from the group consisting of an ester bond, an imide bond, an amide bond, a urethane bond, and a urea bond.

[5]: A wiring board with a metal reinforcement plate, comprising the conductive adhesive layer according to [4] and a metal reinforcement plate.

[6]: An electronic device comprising the wiring board with the metal reinforcement plate according to [5].

[Effects of the Invention]

According to the present disclosure, there is provided a rolled conductive bonding sheet which does not cause blocking when unrolling, has excellent film thickness assurance, has good releasability of a protective sheet, and has high lamination strength and adhesion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a roll-shaped conductive joining sheet according to the present disclosure.

FIG. 2 is a schematic diagram showing a cross section of a wiring board with a metal reinforcing plate according to the present disclosure.

[Explanation of Symbols]

1: Conductive adhesive layer

2: Metal Plate

3: Protective sheet

4: Conductive bonding sheet in roll form

5: Conductive bonding sheet

10: Metal reinforcement plate

20: Patch Panel

21: Insulation film

22: Grounding circuit

23: Overlay

30: Opening

100: Patch panel with metal reinforcement plate

DETAILED DESCRIPTION

The following is a description of the coiled conductive bonding sheet, the wiring board with a metal reinforcement plate, and the electronic device disclosed in the present invention. In addition, unless otherwise specified, the "to" indicating the numerical range includes its lower limit and upper limit. In addition, in order to make the description clear, the drawings are appropriately simplified. In addition, for the purpose of explanation, the scales of the various structures in the drawings may sometimes be very different.

[Conductive bonding sheet]

The conductive bonding sheet of the present disclosure has a protective sheet and a conductive bonding layer and has a flat sheet shape. The conductive bonding layer is preferably laminated directly on the protective sheet or laminated via a release agent layer.

[Conductive bonding sheet in roll form]

The roll-shaped conductive bonding sheet disclosed in the present invention is a member formed by winding the conductive bonding sheet into a roll. A schematic diagram of the roll-shaped conductive bonding sheet of the present invention and a partially enlarged illustration thereof are shown in FIG1. The roll-shaped conductive bonding sheet 4 has a winding core (not shown), forming a structure in which a conductive bonding sheet 5 is wound on the winding core. The conductive bonding sheet 5 is a structure wound in a manner in which the conductive bonding agent layer 1 is on the inner side and the protective sheet 3 is on the outer side.

[Protective film]

The protective sheet serves as a support for the conductive adhesive layer in the conductive bonding sheet and is located on the outermost surface of the roll of the conductive bonding sheet in a roll form, and has the function of protecting the conductive adhesive layer from damage and contamination.

As an example of a protective sheet, there can be listed: plastic sheets such as polyethylene terephthalate, polyethylene naphthalate, polyvinyl fluoride, polyvinylidene fluoride, rigid polyvinyl chloride, polyvinylidene chloride, nylon, polyimide, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polycarbonate, polyacrylonitrile, polybutene, soft polyvinyl chloride, polyethylene, polypropylene, polyurethane, ethylene vinyl acetate copolymer, polyvinyl acetate, etc., paper such as cellophane, woodfree paper, kraft paper, coated paper, various nonwoven fabrics, synthetic paper, metal foil, or a composite film composed of these, etc. Among these, from the viewpoint of easily adjusting the storage elastic modulus by mixing the material components, a plastic sheet is preferred, and polyethylene terephthalate and polyethylene naphthalate having both rigidity and flexibility are more preferred.

The surface of the protective sheet may also be matte treated as needed. Examples of matte treatment methods include sand matting, etching matting, coating matting, chemical matting, mixing matting, etc. From the perspective of improving the peelability of the protective sheet, the surface roughness Ra of the protective sheet on the surface laminated with the conductive adhesive layer in the conductive bonding sheet is preferably 0.01 μm to 1 μm. From the perspective of improving adhesion resistance, the surface roughness Ra of the protective sheet opposite to the surface laminated with the conductive adhesive layer is preferably 0.01 μm to 5 μm.

From the viewpoint of improving the peelability of the protective sheet, the protective sheet is preferably in the form of having a release agent layer on the surface. The release agent layer is preferably formed by coating a release agent. As a release agent, hydrocarbon resins such as polyethylene and polypropylene, higher fatty acids and their metal salts, higher fatty acid soaps, waxes, animal and plant oils and fats, mica, talc, silicone surfactants, silicone oils, silicone resins, alkyd resins, fluorine surfactants, fluorine resins, fluorine-containing silicone resins, melamine resins, acrylic resins, preferably alkyd resins. As a coating method for the release agent, it can be carried out by a conventionally known method, such as a gravure coating method, a kiss coating method, a die coating method, a lip coating method, a notched wheel coating method, a scraper coating method, a roller coating method, a blade coating method, a spray coating method, a rod coating method, a spin coating method, a dip coating method, etc. The release agent layer is preferably formed on a single side of the protective sheet, and more preferably formed on both sides.

The thickness of the protective sheet is not particularly limited, but is preferably 38 μm or more because the protective sheet is not easily damaged when peeled off if it has toughness and strength. From the perspective of preventing heat from penetrating the conductive adhesive layer during temporary bonding or reducing temporary bonding properties, it is preferably 100 μm or less.

[Storage elastic modulus of protective sheet]

The maximum value of the storage elastic modulus of the protective sheet disclosed in the present invention at 25°C to 30°C is preferably 1.0×10 ⁹ Pa or more and 1.5×10 ¹⁰ Pa or less, and more preferably 1.5×10 ⁹ Pa or more and 1.0×10 ¹⁰ Pa or less. In addition, by having the maximum value of the storage elastic modulus of the protective sheet at 25°C to 30°C be 1.0×10 ⁹ Pa or more and 1.5×10 ¹⁰ Pa or less, the rigidity (toughness) of the protective sheet can be fully improved after thermal lamination, and the damage of the protective sheet when peeling the protective sheet from the conductive adhesive layer can be prevented, thereby achieving excellent peelability. In addition, poor winding such as folding wrinkles during winding can be prevented. The storage elastic modulus of the protective sheet can be adjusted by the main chain skeleton, crosslinking density, and orientation of the material or polymer.

[Conductive adhesive layer]

The conductive adhesive layer of the present disclosure is obtained by applying a conductive composition on a protective sheet and drying the composition, and is a non-fluid solid substance at 25° C. and forms a layer with a certain thickness.

From the viewpoint of achieving both thin film properties and electrical conductivity, the thickness of the conductive adhesive layer in the conductive bonding sheet is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and still more preferably 30 μm to 70 μm.

[Probe Adhesion Strength of Conductive Adhesive Layer]

The probe tackiness of the conductive adhesive layer is 5.0 N/cm ² or less. When the probe tackiness of the conductive adhesive layer is 5.0 N/cm ² or less, the adhesion is reduced, and adhesion to the protective layer can be suppressed when the conductive adhesive layer is rolled into a roll, thereby improving the anti-blocking property. The probe tackiness of the conductive adhesive layer is more preferably 3.5 N/cm ² or less. In addition, the lower limit of the probe tackiness is preferably 0 N/cm ² .

The probe tackiness of the conductive adhesive layer in the present disclosure can be controlled, for example, by adjusting the amount of tackifier resin added, such as terpene resin, or by changing the main chain skeleton and side chain of the resin (a-1) contained in the adhesive (A) described later, or by adjusting the crosslinking density based on the amount of curing agent added, or by the type or amount of metal particles and other fillers added. The method for controlling the probe tackiness of the conductive adhesive layer is not limited to the method described above as long as it is a method that can achieve the desired probe tackiness.

[Storage elastic modulus of conductive adhesive layer]

The maximum value of the storage elastic modulus of the conductive adhesive layer at 25°C to 30°C is 1.0×10 ⁷ Pa to 2.0×10 ⁹ Pa. By setting the elastic modulus of the conductive adhesive layer at 25°C to 30°C to 1.0×10 ⁷ Pa or more, when the conductive adhesive sheet is wound into a roll, even if the winding tension is strong and pressure is applied to the conductive adhesive layer, and the rolled state is stored for a long time, the thickness change of the conductive adhesive layer can be suppressed. In addition, by setting the elastic modulus of the conductive adhesive layer at 25°C to 30°C to 2.0×10 ⁹ Pa or less, the cohesive failure of the conductive adhesive layer can be prevented, thereby maintaining high adhesion.

The maximum value of the storage elastic modulus of the conductive adhesive layer at 25°C to 30°C is preferably 1.0×10 ⁷ Pa to 1.7×10 ⁹ Pa, more preferably 1.0×10 ⁸ Pa to 1.3×10 ⁹ Pa.

The maximum value of the storage elastic modulus of the conductive adhesive layer at 70°C to 120°C is preferably 3.0×10 ⁶ Pa to 1.5×10 ⁸ Pa, more preferably 7.0×10 ⁶ Pa to 1.0×10 ⁸ Pa, and further preferably 1.0×10 ⁷ Pa to 8.0×10 ⁷ Pa. When the maximum value of the storage elastic modulus of the conductive adhesive layer at 70°C to 120°C is 3.0×10 ⁶ Pa to 1.5×10 ⁸ Pa, the fluidity of the conductive adhesive layer is generated when temporarily pasting is performed by heat lamination at 110°C, for example, and the lamination strength on the protective sheet can be improved.

The maximum value of the storage elastic modulus of the conductive adhesive layer in the present disclosure can be controlled by, for example, the following methods: changing the main chain skeleton and side chain of the resin, or adjusting the crosslinking density by adjusting the amount of hardener added, adding an adhesion-imparting resin and adjusting the amount of addition, or adjusting by the type or amount of metal particles and other fillers. As the adhesion-imparting resin, for example, terpene resin or terpene phenol resin, rosin or rosin derivatives are preferred.

[Conductive composition]

The conductive composition contains a binder (A) and metal particles (B).

[Binder (A)]

The binder (A) becomes the matrix of the conductive composition and has the function of dispersing and carrying the metal particles (B) or other added fillers. As long as the binder (A) has the above function, the composition is not particularly limited, and preferably contains resin (a-1). The resin (a-1) in the present disclosure is defined as an organic material that is usually (normal temperature) solid, semi-solid or solidified, and has a weight average molecular weight (Mw) of 5,000 or more in the softening or melting range.

[Resin (a-1)]

The composition, molecular structure, etc. of the resin (a-1) are not particularly limited except for the weight average molecular weight (Mw). Among these, the resin having one or more chemical bonds selected from the group consisting of ester bonds, imide bonds, amide bonds, carbamate bonds, and urea bonds is preferred. Imide bonds, amide bonds, carbamate bonds, and urea bonds can interact with the adherend through the non-covalent electron pairs of the nitrogen atoms contained in the bonds to achieve a strong adhesion. As resins having the chemical bond group, for example, polyester resins, polyurethane resins, polyamide resins, polyimide resins, polyamideimide resins, urea resins, and polyurethane urea resins can be listed.

In addition, the resin (a-1) is more preferably selected from the group consisting of ester bonds, imide bonds, amide bonds, carbamate bonds and urea bonds. By having two or more selected from the group consisting of ester bonds, imide bonds, amide bonds, carbamate bonds and urea bonds, the adhesive (A) has multiple interactions with the adherend, which can show a stronger adhesion. The so-called resin having two or more selected from the group consisting of ester bonds, imide bonds, amide bonds, carbamate bonds and urea bonds is, for example, polyester amide, polyamide-imide resin, polyurethane urea resin, etc.

The adhesive (A) preferably contains at least one functional group selected from the group consisting of an epoxy group, an oxetane group, an epithio group, and an aziridine group. In the case where the resin (a-1) has a reactive functional group such as an acidic group, the functional group causes a curing reaction in its reactive functional group or between the functional groups, and can exhibit high adhesion. As a method for making the adhesive (A) contain the functional group, for example, the following method can be adopted: adding the resin (a-1) having the functional group to the adhesive (A), or adding the curing agent having the functional group in the curing agent (C) described later to the adhesive (A).

As described above, the resin (a-1) can be appropriately selected from the viewpoint of composition and molecular structure, but an appropriate resin can also be selected according to the properties of the resin. From the viewpoint of applying thermal stimulation to the conductive composition to make it develop adhesion, the resin (a-1) is preferably a thermosetting resin (a-2) or a thermoplastic resin (a-3).

[Thermosetting resin (a-2)]

Thermosetting resin (a-2) is a thermosetting resin among resins (a-1). Thermosetting is defined as "a resin that can be cured by heating or other means such as radiation, catalysts, etc., and can be converted into a substantially infusible and insoluble product."

The thermosetting property can be exhibited by the reaction of the reactive functional groups when the thermosetting resin (a-2) has reactive functional groups such as acidic groups, or can be exhibited by the reaction of the thermosetting resin (a-2) with reactive functional groups incorporated into the curing agent (C) described later. When the thermosetting resin (a-2) is used in the conductive adhesive layer, the probe tack adhesion, storage elastic modulus at 25°C to 30°C, and storage elastic modulus at 70°C to 120°C of the conductive adhesive layer are values before the thermosetting reaction.

The acid value of the thermosetting resin (a-2) is preferably 5 mgKOH/g to 40 mgKOH/g. When the acid value is within the above range, the density of the cross-linked structure is within an appropriate range, and flexibility and toughness can coexist. The acid value is more preferably 10 mgKOH/g to 20 mgKOH/g.

[Thermoplastic resin (a-3)]

Thermoplastic resin (a-3) is a thermoplastic resin among resins (a-1). Thermoplasticity is defined as "a state in which a plastic can be repeatedly softened by heating and hardened by cooling within a temperature range specific to plastics, and can be repeatedly molded, extruded or formed into an article in a uniform shape by flowing in a softened state".

[Hardener (C)]

The hardener (C) in the present disclosure is a substance that promotes or regulates the hardening reaction, and is defined as a substance having a molecular weight or weight average molecular weight (Mw) of less than 5,000. The so-called hardening reaction is defined as "polymerization and/or crosslinking of a prepolymer or a polymer composition by heating or other means such as radiation, a catalyst, etc., so that the elastic modulus increases irreversibly". In the adhesive (A), from the viewpoint of forming polymerization and/or crosslinking by stimulation such as heat so that the conductive composition exhibits strong adhesion, the adhesive (A) of the present disclosure preferably contains a hardener (C).

The curing reaction may be a reaction in which the curing agent (C) reacts with itself, or may react with other components in the binder (A) such as the resin (a-1). In the case where the resin (a-1) and the curing agent (C) undergo a curing reaction, the resin (a-1) is preferably a thermosetting resin (a-2) from the viewpoint of efficiently reacting.

From the viewpoint that the curing reaction does not proceed during storage but only occurs upon heating, the combination of the thermosetting resin (a-2) and the curing agent (C) is preferably a combination that does not undergo a crosslinking reaction at 50°C but accelerates the curing reaction at 150°C.

Furthermore, by appropriately combining two or more curing agents having different starting temperatures for the curing reaction, the crosslinking density of the conductive composition in each temperature range can be controlled.

Examples of the curing agent (C) include epoxy curing agents, oxetane curing agents, episulfide curing agents, aziridine curing agents, amine curing agents, isocyanate curing agents, and imidazole curing agents. Among them, epoxy curing agents, oxetane curing agents, episulfide curing agents, and aziridine curing agents are preferred because they can efficiently undergo a curing reaction with the thermosetting resin (a-2) and exhibit high adhesion.

As the epoxy curing agent, for example, a glycidyl ether epoxy compound, a glycidyl amine epoxy compound, a glycidyl ester epoxy compound, a cyclic aliphatic (alicyclic) epoxy compound, etc. are preferable.

Examples of the glycidyl ether epoxy compound include bisphenol A epoxy compounds, bisphenol F epoxy compounds, bisphenol S epoxy compounds, bisphenol AD epoxy compounds, cresol novolac epoxy compounds, phenol novolac epoxy compounds, α-1-naphthol novolac epoxy compounds, bisphenol A novolac epoxy compounds, dicyclopentadiene epoxy compounds, tetrabromobisphenol A epoxy compounds, brominated phenol novolac epoxy compounds, tris(glycidyloxyphenyl)methane, tetrakis(glycidyloxyphenyl)ethane, and the like.

Examples of the glycidylamine epoxy compound include tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, triglycidylmetaaminophenol, and tetraglycidylmeta-xylylenediamine.

As said glycidyl ester type epoxy compound, diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate etc. are mentioned, for example.

Examples of the cyclic aliphatic (alicyclic) epoxy compound include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate and bis(epoxycyclohexyl)adipate.

Examples of the oxetane curing agent include 1,4-bis{[(3-ethyloxetan-3-yl)methoxy]methyl}benzene, 3-ethyl-3-{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 1,3-bis[(3-ethyloxetan-3-yl)methoxy]benzene, 4,4′-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl, an ester of (2-ethyl-2-oxetanyl)ethanol and terephthalic acid, an etherified product of (2-ethyl-2-oxetanyl)ethanol and a phenol novolac resin, and an esterified product of (2-ethyl-2-oxetanyl)ethanol and a polycarboxylic acid compound.

Examples of the episulfide curing agent include bis(1,2-epithioethyl)sulfide, bis(1,2-epithioethyl)disulfide, bis(2,3-epithiopropyl)sulfide, bis(2,3-epithiopropylthio)methane, bis(2,3-epithiopropyl)disulfide, bis(2,3-epithiopropyldithio)methane, bis(2,3-epithiopropyldithio)ethane, bis(6,7-epithio-3,4-dithioheptyl)sulfide, Bis(6,7-epithio-3,4-dithioheptyl)disulfide, 1,4-dithiane-2,5-bis(2,3-epithiopropyldithiomethyl), 1,3-bis(2,3-epithiopropyldithiomethyl)benzene, 1,6-bis(2,3-epithiopropyldithiomethyl)-2-(2,3-epithiopropyldithioethylthio)-4-thiohexane, 1,2,3-tris(2,3-epithiopropyldithio)propane, and the like.

Examples of the aziridine curing agent include trimethylolpropane-tri-a-2-aziridinyl propionate, tetramethylolmethane-tri-a-2-aziridinyl propionate, N,N′-diphenylmethane-4,4′-bis(1-aziridinecarboxamide), and N,N′-hexamethylene-1,6-bis(1-aziridinecarboxamide).

Examples of the amine curing agent include diethylenetriamine, triethylenetetramine, methylenebis(2-chloroaniline), methylenebis(2-methyl-6-methylaniline), 1,5-naphthalene diisocyanate, and n-butylbenzyl phthalate.

Examples of the isocyanate curing agent include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, 1,5-naphthalene diisocyanate, tetramethylxylylene diisocyanate, and trimethylhexamethylene diisocyanate.

Examples of the imidazole curing agent include 2-methylimidazole, 2-heptadecylimidazole, 2-phenyl-4-methylimidazole, and 1-cyanoethyl-2-undecylimidazolium trimellitate.

The curing agent (C) may be used alone or in combination of two or more. In order to adjust the storage elastic modulus or glass transition temperature of the conductive composition, the curing agent (C) preferably has a molecular weight or a weight average molecular weight of 100 or more.

The curing agent (C) is preferably formulated in an amount of 0.1 to 70 parts by mass, more preferably 0.1 to 50 parts by mass, relative to 100 parts by mass of the thermosetting resin (a-2). By setting the addition amount of the curing agent (C) to 0.1 parts by mass or more, the density of the cross-linked structure of the conductive composition can be optimized, the adhesion is improved, and the film thickness guarantee can be improved. By setting the addition amount of the curing agent (C) to 70 parts by mass or less, the conductive composition can be prevented from being excessively hardened, and the adhesion and stamping processability can be improved.

[Metal particles (B)]

The metal particles (B) are preferably conductive metals such as gold, platinum, silver, copper and nickel, and alloys thereof. In addition, for the metal that becomes the core body rather than the microparticles of a single composition, from the viewpoint of reducing costs, it is preferred to form a composite microparticle with a coating layer covering the surface of the core body from a raw material with higher conductivity than the core body.

The core is preferably selected from nickel, silicon dioxide, copper and alloys thereof. Examples of the coating layer include gold, platinum, silver, tin, manganese, indium and alloys thereof. Among them, silver is preferably used from the viewpoint of conductivity and material cost.

The composite microparticle preferably has a coating layer in a ratio of 1 to 40 parts by mass relative to 100 parts by mass of the core, more preferably 5 to 30 parts by mass. If coated with 1 to 40 parts by mass, electrical conductivity can be maintained while further reducing costs. In addition, the composite microparticle preferably has a coating layer that completely covers the core. However, there is actually a situation where a portion of the core is exposed. In this case, if the conductive material covers more than 70% of the surface area of the core, it is easy to maintain electrical conductivity.

The metal particles (B) may be used alone or in combination of two or more.

The shape of the metal particles (B) is not limited as long as the desired conductivity can be obtained. For example, spherical, flaky, leaf-shaped, dendritic, plate-shaped, needle-shaped, rod-shaped, grape-shaped, and amorphous blocks can be listed. In addition, from the viewpoint of improving conductivity, spherical, flaky, leaf-shaped, dendritic, and plate-shaped are more preferred.

Regarding the average particle size of the metal particles (B), the average particle size D ₅₀ is preferably 1 μm to 50 μm, more preferably 3 μm to 30 μm, and further preferably 5 μm to 20 μm. When the average particle size D ₅₀ is 1 μm to 50 μm, an appropriate conductive path can be formed, and the conductivity can be improved. In addition, the average particle size D ₅₀ can be obtained by a laser diffraction-scattering particle size distribution measuring device.

The average particle size of the metal particles (B) is preferably 1 to 120 μm, more preferably 5 to 70 μm. When the average particle size D ₉₀ is 1 to 120 _μm , the occurrence of blocking can be suppressed.

The value X obtained by dividing the thickness of the conductive adhesive layer by the average particle size D ₅₀ of the metal particles (B) is preferably 1 to 35. When X is 35 or less, a conductive path of the metal particles (B) is effectively formed in the conductive adhesive layer, and the conductivity is improved. From the viewpoint of improving the conductivity, X is more preferably 18 or less. In addition, when X is 1 or more, the contact points between the adherend and the metal particles (B) are not excessively increased, and the contact area between the adherend and the adhesive (A) is increased, so the adhesion is improved. X is more preferably 5 or more.

The metal particles (B) are preferably contained in 40% to 90% by mass of the total solid content of the conductive composition. By setting the content to the above, anti-blocking, film thickness guarantee, and adhesion can coexist. The content of the metal particles (B) is more preferably 45% to 80% by mass, and further preferably 50% to 70% by mass.

The conductive composition in the present embodiment may also contain a heat stabilizer, an inorganic filler, an organic filler, a pigment, a dye, a tackifier resin, a plasticizer, a silane coupling agent, an ultraviolet absorber, a defoamer, a leveling agent, and the like as other optional components.

Examples of the inorganic filler include silicon dioxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, talc, montmorillonite, kaolin, bentonite, etc. The conductive composition contains an inorganic filler, which can control the suppression of probe viscosity, and further control the storage elastic modulus and the film thickness guarantee.

Examples of the organic filler include urethane resin particles, acrylic resin particles, phenol resin particles, nylon particles, etc. When the conductive composition contains an organic filler, temporary adhesiveness can be ensured while controlling the storage elastic modulus and the film thickness guarantee.

[Method for producing conductive bonding sheet]

The conductive bonding sheet disclosed in the present invention can be obtained, for example, by applying a conductive composition on a protective sheet, drying it, and then performing B-stage hardening as needed. The dried conductive composition is referred to as a conductive bonding agent layer. The coating method can be appropriately selected from known methods, taking into account the film thickness of the conductive bonding agent layer. As specific examples of coating methods, there can be listed: gravure coating method, matching coating method, die coating method, lip coating method, notch wheel coating method, blade coating method, roller coating method, knife coating method, spray coating method, rod coating method, spin coating method, dip coating method, etc.

B-stage curing is a method of partially causing a curing reaction by heating the conductive adhesive layer at a predetermined temperature and time. By performing B-stage curing, the strength of the conductive adhesive layer can be improved while maintaining the adhesion.

[Method for producing a roll-shaped conductive bonding sheet]

The conductive bonding sheet can be rolled up by pressing the front end of the conductive bonding sheet onto a winding core material and winding the conductive bonding sheet.

The winding core material disclosed in the present invention is not particularly limited, and examples thereof include paper tubes, metal tubes, and plastic tubes. Generally, it is a tube that is long in the horizontal width direction and used in a winding device attached to a manufacturing device such as a printing machine, a coating machine, a molding machine, and a yarn twisting machine. Regarding the winding core material, it is generally preferred that the diameter is about 1 cm to 40 cm. In addition, the horizontal width of the winding core material is not particularly limited as long as it is a width that can be set in the winding device. Generally, it is about 2 mm to 6 m.

As another method for winding up the conductive bonding sheet, an example may be given: a method of using an adhesive member to fix the front end of the conductive bonding sheet to a winding core material for winding up. Adhesive members include double-sided adhesive tape, cast adhesive tape, and single-sided adhesive tape. As a first method, an example may be given: a method of using a double-sided adhesive tape to fix the conductive adhesive layer of the front end of the conductive bonding sheet to the winding core material. In addition, as a second method, an example may be given of a method of using a double-sided adhesive tape to fix the protective sheet surface of the front end of the conductive bonding sheet to the winding core material. After the conductive bonding sheet is fixed to the winding core material using the first method or the second method, winding up begins.

The tension when winding the conductive bonding sheet varies depending on the material of the protective sheet, etc., and is not particularly limited, but needs to be set to a tension that does not deform the protective sheet and does not cause the protective sheet to relax. For example, when polyethylene terephthalate (PET) is used as the protective sheet, it is preferably 0.5 N/cm to 2.5 N/cm.

[Metal reinforcement plate]

In the metal reinforcement plate disclosed in the present invention, a conductive adhesive layer is attached to the metal plate. The metal plate may be, for example, conductive metals such as gold, silver, copper, iron and stainless steel. Among these, stainless steel is preferred in terms of strength, cost and chemical stability as a metal plate. The thickness of the metal plate is generally about 0.04 mm to 1 mm. The metal plate preferably has a nickel layer formed on the entire surface of the metal plate. The nickel layer is preferably formed by electrolytic nickel plating. The thickness of the nickel layer is about 0.5 μm to 5 μm, more preferably 1 μm to 4 μm. In addition, the conductive adhesive layer included in the metal reinforcement plate is a non-flowing solid substance at 25°C, and is in a layered form with a certain thickness.

[Distribution panel with metal reinforcement plate]

The wiring board 100 with a metal reinforcement plate of the present embodiment (refer to FIG. 2 ) is configured with: a wiring board 20, a ground circuit 22 is arranged on an insulating film 21, a cover layer 23 covers the ground circuit 22, and a part of the ground circuit 22 is exposed through an opening 30; and a metal reinforcement plate 10, which is located on the wiring board 20. The conductive adhesive layer 1 of the metal reinforcement plate 10 is in a layered state, and the wiring board 20 is bonded to the metal plate 2. In the wiring board 20 of the present embodiment, the ground circuit 22 and the metal plate 2 are electrically connected through the conductive adhesive layer 1 by filling a part of the conductive adhesive layer 1 into the opening 30. Signal wiring can also be provided on the wiring board 20.

The area of the opening 30 of the wiring board 20 can be set to be greater than or equal to 0.16 mm ² and less than or equal to 0.81 mm ^2. By setting the area of the opening 30 to be greater than or equal to 0.16 mm ² , the filling property of the conductive adhesive layer into the opening 30 can be improved. In addition, by setting the area of the opening 30 to be less than or equal to 0.81 mm ² , the area occupied by the opening 30 in the wiring board 20 can be reduced. The area of the opening 30 is preferably set to be greater than or equal to 0.25 mm ² and less than or equal to 0.64 mm ² , and more preferably set to be greater than or equal to 0.36 mm ² and less than or equal to 0.49 mm ^2. When the area of the opening 30 is greater than or equal to 0.16 mm ² and less than or equal to 0.81 mm ² , the filling property of the conductive adhesive layer into the opening 30 can be improved, and the contact resistance between the conductive adhesive layer and the ground circuit 22 can be reduced.

The shape of the opening 30 in a plan view may be a rectangular shape or a circular shape. When the opening 30 is a rectangular shape, it becomes particularly difficult to fill the four corners of the rectangular opening with the conductive adhesive layer, and gaps are easily formed at the four corners. However, by using the conductive adhesive layer of the present embodiment in which the resin flow is controlled within an appropriate range, the conductive adhesive layer can be well filled into the opening even in a rectangular opening.

[Electronic equipment]

Such a wiring board with a metal reinforcement plate can be installed in electronic devices such as mobile phones, smart phones, personal computers (PCs), digital cameras, liquid crystal displays, etc. In addition, it can also be appropriately installed in transportation equipment such as automobiles, trains, ships, and airplanes.

[Example]

Hereinafter, the present disclosure will be described in more detail by way of examples and comparative examples, but the present disclosure is not limited to the following examples. In addition, the following "parts" and "%" are values based on "parts by mass" and "% by mass", respectively. In addition, the acid value and weight average molecular weight (Mw) of the resin (a-1) and the D ₅₀ average particle size of the metal particles (B) were measured by the following method.

[Acid value of resin (a-1)]

According to the neutralization titration method of Japanese Industrial Standards (JIS) K 0070, the acid value (mgKOH/g) is converted into solid content to obtain the acid value. Accurately measure about 1g of the sample in a co-stoppered conical flask, add 100mL of a mixture of tetrahydrofuran/ethanol (volume ratio: tetrahydrofuran/ethanol = 2/1) and dissolve it. Add phenolphthalein test solution as an indicator, and titrate with 0.1N alcoholic potassium hydroxide solution. The end point is when the indicator remains light red for 30 seconds. The acid value is obtained by the following formula (unit: mgKOH/g).

Acid value (mgKOH/g) = (5.611×a×F)/S

in,

S: Sample collection amount (g)

a: Consumption of 0.1N alcoholic potassium hydroxide solution (mL)

F: The force value of 0.1N alcoholic potassium hydroxide solution

[Weight average molecular weight (Mw) of resin (a-1)]

The determination of Mw is performed by gel permeation chromatography (GPC) "HPC-8020" (manufactured by Tosoh Corporation). GPC is a liquid chromatograph that separates and quantifies substances dissolved in a solvent (THF: tetrahydrofuran) according to the difference in their molecular size. This determination is performed by connecting two "LF-604" (manufactured by Showa Denko: GPC column for rapid analysis: 6mmID×150mm size) in series on the column, at a flow rate of 0.6mL/min and a column temperature of 40°C. The determination of Mw is performed using polystyrene conversion.

[D ₅₀ average particle size of metal particles (B)]

The _D50 average particle size was measured using a laser diffraction-scattering particle size distribution measuring device LS13320 (manufactured by Beckman-Coulter). It is a value obtained by measuring the metal particles (B) using a cyclone-dried powder sample module, and is the particle size at which the cumulative value in the cumulative distribution of particle diameters is 50%. In addition, the refractive index was set to 1.6.

<Raw Materials>

[Binder (A)]

(a-1)-1: Polyester resin: acid value 36 mgKOH/g, Mw=27,000 (manufactured by TOYO CHEM)

(a-1)-2: Polyimide resin: acid value 18 mgKOH/g, Mw=55,000 (manufactured by TOYO CHEM)

(a-1)-3: Polyamide resin: acid value 22 mgKOH/g, Mw=49,000 (manufactured by TOYO CHEM)

(a-1)-4: Polyurethane resin: acid value 16 mgKOH/g, Mw = 98,000 (manufactured by TOYO CHEM)

(a-1)-5: Polyurethane urea resin: acid value 15 mgKOH/g, Mw=100,000 (manufactured by TOYOCHEM)

(a-1)-6: Styrene elastomer: acid value 55 mgKOH/g, Mw=120,000 (manufactured by TOYO CHEM)

[Metal particles (B)]

B1: Silver-coated copper powder: D ₅₀ = 5.7 μm, dendritic (manufactured by Mitsui Mining & Smelting Co., Ltd.)

B2: Silver-coated copper powder: D ₅₀ = 31.2 μm, dendritic (manufactured by Mitsui Mining & Smelting Co., Ltd.)

B3: Silver-coated copper powder: D ₅₀ = 10.8 μm, spherical (manufactured by Resonac)

B4: Silver-coated copper powder: D ₅₀ = 7.5 μm, spherical (manufactured by Resonac)

B5: Silver-coated copper powder: D ₅₀ = 11.3 μm, flake-shaped (manufactured by DOWA Holdings)

[Hardener (C)]

C1: Ti chelate (TC100, molecular weight = 364, Matsumoto Fine Chemical)

C2: Bisphenol A type epoxy compound (jER (registered trademark) 828, molecular weight = 370, manufactured by Mitsubishi Chemical)

C3: Isophthalic acid type oxetane compound (ETERNACOLL (registered trademark) OXIPA, molecular weight = 362, manufactured by Ube Industries)

C4: Hydrogenated bisphenol A episulfide compound (TBIS (registered trademark)-AHS, molecular weight = 384, manufactured by Taoka Chemical Industry Co., Ltd.)

C5: Polyfunctional aziridine compound (Chemitite (registered trademark) PZ-33, molecular weight = 425, manufactured by Nippon Catalyst)

C6: Polycarbodiimide compound (Carbodilite V-05, molecular weight = 1200, manufactured by Nisshinbo Chemical)

[Adhesive resin]

Terpene resin (YS resin PX300N, manufactured by Yasuhara Chemical)

[Protective sheet (D)]

D1: PET film (Cerapeel PJ271, film thickness 50 μm, surface treatment: single-sided alkyd release agent treatment, manufactured by Toray)

D2: Paper film (G62 white AA (N7-82), film thickness 58 μm, surface treatment: double-sided silicone release agent treatment, manufactured by Lnteci)

D3: Polypropylene film (Trefin #30-2500H, film thickness 50 μm, surface treatment: double-sided alkyd release agent treatment, manufactured by Toray)

D4: Polyethylene film (UBEPOLYSHEET, film thickness 70 μm, surface treatment: double-sided alkyd release agent treatment, manufactured by Ube Film)

D5: Polyvinyl chloride film (generally polyvinyl chloride (PVC) film, film thickness 120 μm, surface treatment: double-sided alkyd release agent treatment, manufactured by Okamoto)

<Production of Conductive Composition and Conductive Joining Sheet>

[Example 1]

100 parts by mass of ((a-1)-1) as the resin (a-1), 167 parts by mass of (B1) as the metal particles (B), and 10 parts by mass of a terpene resin (YS resin PX300N) as a tackifier resin were added, and methyl ethyl ketone as a solvent was added and mixed so that the non-volatile component concentration became 40% by mass. Then, 1.5 parts by mass of (C1) as the hardener (C) was added, and the mixture was stirred for 10 minutes using a stirrer to prepare a conductive composition solution.

Next, the prepared conductive composition solution was applied to one of the peeling-treated surfaces of D1 (release agent: alkyd release agent) as a protective sheet (D) with a width of 300 mm using a comma head coater at a line speed of 2 m/min so that the thickness after drying was 60 μm, and dried in an electric oven A set at 100° C. for 2 m and an electric oven B set at 120° C. for 2 m, thereby forming a conductive adhesive layer on the protective sheet. Subsequently, the conductive adhesive sheet was wound on a plastic core with a diameter of 8.8 cm so that the conductive adhesive layer of the conductive adhesive sheet was located inside, thereby obtaining a rolled conductive adhesive sheet.

[Example 2 to Example 36, Comparative Example 1 to Comparative Example 4]

Except that the types and amounts of the components to be blended were as shown in Tables 1 to 6, the same operation as in Example 1 was carried out to obtain roll-shaped conductive bonding sheets of Examples 2 to 36 and Comparative Examples 1 to 4.

[Measurement of probe adhesion]

The conductive bonding sheet was unrolled from each of the obtained roll-shaped conductive bonding sheets, and probe adhesion measurement was performed according to "The Seventeenth Revised Japanese Pharmacopoeia General Test Method 6. Preparation Test Method 6.12 Adhesion Test Method 3.4 Probe Adhesion Test Method". The conductive bonding sheet was cut into 2 cm squares to obtain samples. The sample was attached to a weight ring, and a total of 200 g of weights were placed on it to apply a load, and the probe adhesion adhesion (unit N/ ^cm2 ) was measured using a probe adhesion tester (TE-6001 probe adhesion tester, manufactured by Tester Industry Co., Ltd.).

[Measurement of storage elastic modulus]

The storage elastic modulus of each conductive adhesive layer and protective sheet was measured using a dynamic viscoelasticity measuring apparatus (DVA-200, manufactured by IT Measurement & Control Co., Ltd.).

The conductive adhesive layer and the protective sheet were cut into a width of 5 mm and a length of 5 cm to obtain a sample. The device was set to a constant temperature increase (10°C/min), and the measurement was carried out in a tensile mode with a measurement frequency of 10 Hz in a temperature range of -50°C to 300°C, thereby measuring the storage elastic modulus (unit: Pa) at each temperature, and the maximum value at 25°C to 30°C and 70°C to 120°C was obtained.

<Evaluation>

The obtained roll-shaped conductive bonding sheets were evaluated for blocking resistance, film thickness guarantee, protective sheet peelability, lamination strength, and adhesiveness according to the following methods. The evaluation results are shown in Tables 1 to 5.

[Blocking resistance]

The following roll sample, i.e., the roll-shaped conductive bonding sheet prepared in each example and comparative example was cut into a width of 249 mm and a length of 10 m and wound around a plastic tube with a diameter of 8.8 cm at a winding tension of 1.6 N/cm so that the conductive bonding layer was located inside, was left at 50° C. for 24 hours. Thereafter, the conductive bonding sheet was unwound from the roll, and the adhesion was evaluated according to the following criteria.

+++: The conductive adhesive layer was not attached to the protective sheet surface (very excellent).

++: A portion of the conductive adhesive layer adhered to the protective sheet surface, but the conductive adhesive layer did not float up (excellent).

+: A part of the conductive adhesive layer adheres to the protective sheet surface, and a part of the conductive adhesive layer floats (practically applicable).

Not acceptable (NG): The conductive adhesive layer was attached to the protective sheet surface, and a portion of the conductive adhesive layer was broken (not practical).

[Film thickness guarantee]

The rolled conductive bonding sheets prepared in the examples and comparative examples were cut into pieces with a width of 249 mm and a length of 10 m, and rolled up on a plastic tube with a diameter of 8.8 cm at a winding tension of 1.9 N/cm with the conductive bonding agent layer located inside to prepare roll samples, which were placed in an environment of 50° C. for 240 hours.

Next, 10 m was unwound from the outer roll of the coil sample, and a 5 cm square sample was collected, and the thickness (H1) of the conductive adhesive layer was measured using a contact film thickness meter. The initial thickness of the conductive adhesive layer of the conductive bonding sheet, 60 μm, was set as H2, and ΔH=H1/H2 was calculated for each example and comparative example, and the evaluation was performed according to the following evaluation criteria.

+++: ΔH is 0.6 or more (very excellent).

++: ΔH is 0.5 or more and less than 0.6 (excellent).

+: ΔH is 0.4 or more and less than 0.5 (practically applicable).

NG: ΔH is less than 0.4 (not practical).

[Removability of protective sheet]

A conductive bonding sheet with a width of 25 mm and a length of 100 mm was cut from the roll-shaped conductive bonding sheet prepared in each embodiment and comparative example, and the conductive bonding sheet was overlapped in such a way that the conductive bonding layer was overlapped with a stainless steel (SUS) plate with a width of 30 mm and a length of 150 mm (a material in which a nickel layer with a thickness of 2 μm was formed on the surface of a commercially available SUS304 plate with a thickness of 0.2 mm). Subsequently, the conductive bonding sheet and the SUS plate were laminated using a roll laminator at 130°C, ³ kgf/cm2, and 0.5 m/min, and then the protective sheet was peeled off from the conductive bonding layer. Thereafter, the remaining area of the protective sheet remaining on the conductive bonding layer was measured, and the residual rate of the protective sheet was calculated according to the following formula, and evaluated according to the following evaluation criteria.

Remaining rate of protective sheet = Remaining area of protective sheet/Area of conductive adhesive layer×100

+++: The remaining rate of the protective sheet is 0% (very excellent).

++: The residual rate of the protective sheet is more than 0% and less than 1% (excellent).

+: The remaining rate of the protective sheet is 1% or more and less than 2% (practically possible).

NG: The remaining rate of the protective sheet is 2% or more (not practical).

[Lamination strength]

A conductive bonding sheet with a width of 25 mm and a length of 100 mm was cut from the roll-shaped conductive bonding sheet prepared in each example and comparative example, and the conductive bonding sheet was overlapped in such a manner that the conductive bonding layer was overlapped with a SUS plate with a width of 30 mm and a length of 150 mm (a nickel layer with a thickness of 2 μm was formed on the surface of a commercially available SUS304 plate with a thickness of 0.2 mm). Subsequently, the conductive bonding sheet and the SUS plate were roll-laminated using a roll laminator under the conditions of 130° C., 3 kgf/cm ² , and 0.5 m/min, and then the protective sheet was peeled off from the conductive bonding layer, and a copper foil (thickness of 25 μm) was overlapped on the exposed surface of the conductive bonding layer, and the conductive bonding layer and the copper foil were roll-laminated using a roll laminator under the conditions of 130° C., 3 kgf/cm ² , and 0.5 m/min to obtain an evaluation sample.

Then, using a tensile tester (small table tester EZ-TEST, manufactured by Shimadzu Corporation), under the condition of a tensile speed of 50 mm/min, the temporary adhesiveness was evaluated according to the following evaluation criteria, using the bonding strength of the conductive adhesive layer of the evaluation sample to the SUS plate in the 90° peel test as an indicator.

+++: Adhesion strength is 3 N/cm or more (very excellent).

++: Adhesion strength is 2 N/cm or more and less than 3 N/cm (excellent).

+: Adhesion strength is 1 N/cm or more and less than 2 N/cm (practically applicable).

NG: The bonding strength is less than 1 N/cm (not practical).

[Adhesion]

A conductive bonding sheet with a width of 25 mm and a length of 100 mm was cut from the roll-shaped conductive bonding sheet prepared in each embodiment and comparative example, and the conductive bonding sheet was overlapped in such a manner that the conductive bonding layer was overlapped with a metal plate with a width of 30 mm and a length of 150 mm (a material in which a nickel layer with a thickness of 2 μm was formed on the surface of a commercially available SUS304 plate with a thickness of 0.2 mm). Subsequently, the conductive bonding sheet and the metal plate were roll-laminated using a roll laminator under the conditions of 130° C., 3 kgf/cm ² , and 0.5 m/min, and then the protective sheet was peeled off from the conductive bonding layer, and a copper foil (thickness of 25 μm) was overlapped on the exposed surface of the conductive bonding layer, and the conductive bonding layer and the copper foil were roll-laminated using a roll laminator under the conditions of 130° C., 3 kgf/cm ² , and 0.5 m/min to obtain a laminate. The laminate was subjected to a pressure bonding treatment under the conditions of 170° C., 2 MPa, and 3 minutes, and then subjected to a heat treatment in an electric oven at 160° C. for 60 minutes, thereby obtaining a sample for evaluation.

Next, using a tensile tester (small table tester EZ-TEST, manufactured by Shimadzu Corporation), under the condition of a tensile speed of 50 mm/min, the adhesive strength of the conductive composition of the evaluation sample to the metal plate in a 90° peel test was used as an index, and the adhesiveness was evaluated according to the following evaluation criteria.

+++: Adhesion strength is 4 N/cm or more (very excellent).

++: Adhesion strength is 3 N/cm or more and less than 4 N/cm (excellent).

+: Adhesion strength is 1 N/cm or more and less than 3 N/cm (practically applicable).

NG: Adhesion strength is less than 1 N/cm (not practical).

Claims (6)

1. A roll-shaped conductive bonding sheet, wherein a conductive bonding sheet is wound into a roll shape, wherein: The conductive bonding sheet comprises a protective sheet and a conductive bonding agent layer. The probe adhesion of the conductive adhesive layer is 5.0 N/ ^cm2 or less. The conductive adhesive layer has a maximum value of a storage elastic modulus of 1.0×10 ⁷ Pa to 2.0×10 ⁹ Pa at 25° C. to 30° C. 2 . The rolled conductive bonding sheet according to claim 1 , wherein the conductive bonding agent layer has a maximum value of a storage elastic modulus of 3.0×10 ⁶ Pa to 1.5×10 ⁸ Pa at 70° C. to 120° C. 3 . 3 . The rolled conductive bonding sheet according to claim 2 , wherein the maximum value of the storage elastic modulus of the protective sheet at 25° C. to 30° C. is 1.0×10 ⁹ Pa or more. 4 . The rolled conductive bonding sheet according to claim 1 , wherein the conductive bonding agent layer comprises a resin having one or more chemical bonds selected from the group consisting of an ester bond, an imide bond, an amide bond, a urethane bond, and a urea bond. 5. A wiring board with a metal reinforcing plate, comprising the conductive adhesive layer according to claim 4 and a metal reinforcing plate. 6. An electronic device comprising the wiring board with a metal reinforcing plate according to claim 5.