Base material for mounting electronic device and roll-shaped package of same

Abstract

The present invention is a base material for mounting an electronic device, the base material comprising a metal foil and a protective resin layer and being characterized in that the protective resin layer is provided on the surface on one side of the metal foil, the surface on the other side of the metal foil is the electronic device mounting side surface, and a hygroscopic resin layer and an electrode foil are provided on the other-side surface of the metal foil in that order from the other-side surface of the metal foil. This base material for mounting an electronic device prevents permeation of water, thereby making it possible to hold the electronic device in a dry state and prevent the occurrence of rust on the electrode foil.

Description

Base material for mounting electronic devices and its roll-shaped package

[0001] The present invention relates to a base material for mounting electronic devices, and more particularly, to a base material for mounting electronic devices that is used to block and absorb moisture to keep the electronic device in a dry state.

[0002] Conventionally, a moisture-absorbing sheet provided with a moisture-absorbing resin layer in which a desiccant is dispersed has been widely used for moisture absorption and moisture prevention. As such a moisture-absorbing sheet, those having various layer configurations have been proposed. In Patent Document 1, a moisture-absorbing sheet including a desiccant layer, a moisture-permeable sheet provided on one surface of the desiccant layer, and an adhesive layer provided on the other surface of the desiccant layer has been proposed. It is described that a cellophane sheet, an acetate sheet, a nylon sheet, etc. are used as the moisture-permeable sheet.

[0003] By the way, electronic devices such as organic electroluminescence (organic EL), solar cells, touch panels, and electronic papers developed in recent years dislike charge leakage, so high moisture barrier properties are required for plastic base materials such as plastic base materials forming their circuit boards or films sealing the circuit boards.

[0004] However, the known moisture-absorbing sheets disclosed in Patent Document 1 and the like do not show satisfactory performance as a sealing material for keeping the inside of the above-mentioned organic electro devices in a dry state. That is, by absorbing a large amount of moisture invading from the outside of the device, the desiccant present in the moisture-absorbing sheet reaches a saturated state in a short period of time. Further improvement is necessary because the moisture absorbency is impaired or the absorbed moisture is released into the device.

[0005] On the other hand, in an electronic device, an electrode foil is patterned as a wiring and electrically connected to a cell inside the device.

[0006] Patent Document 2 describes a solar cell module comprising: a wiring sheet having a wiring portion (wiring pattern) formed on its surface; a light-receiving surface for receiving light to generate electricity; and a connection electrode for wiring formed on the surface opposite to the light-receiving surface, wherein the connection electrode is connected to the wiring pattern on the wiring sheet via a conductive connecting member; a light-transmitting substrate disposed in an area covering the light-receiving surface of the solar cell and the wiring sheet; an electrically insulating back-side sealing portion filled in a layered space at least between the surface of the wiring sheet on which the wiring pattern is formed and the surface of the solar cell on which the connection electrode is formed; and a light-transmitting light-receiving surface-side sealing portion laminated in close contact with the back-side sealing portion and the light-receiving surface of the solar cell and in close contact with the light-transmitting substrate, wherein the solar cell is sealed between the wiring sheet and the light-transmitting substrate by the back-side sealing portion and the light-receiving surface-side sealing portion. In this solar cell module, the wiring pattern is made of patterned metal foil, and the connection electrode and the wiring pattern are electrically connected via a connecting member.

[0007] However, since the wiring is made of metal foil, it may rust if it comes into contact with moisture. If rust occurs, problems such as deterioration of conductivity may occur.

[0008] Patent Document 3 describes a bonding material assembly for a solar cell, comprising a sheet-like substrate, a substrate electrode portion formed of a plate-like or sheet-like metal and provided on the substrate, and an easy-connection layer provided on the substrate electrode portion to improve the electrical connectivity between the substrate electrode portion and a conductive bonding material disposed on the substrate electrode portion. It is stated that copper or aluminum is used as the material for the substrate electrode portion, and that the surface may be decorated with nickel plating or the like for rust prevention.

[0009] However, rust prevention treatments such as nickel plating are generally applied to the substrate electrode portion (i.e., the metal electrode foil) before patterning. Therefore, once the substrate electrode portion is patterned, areas on the sides of the patterned substrate electrode portion will not be treated with rust prevention, and rust may develop in these areas when exposed to moisture.

[0010] Japanese Patent Publication No. 2006-326838, Japanese Patent Publication No. 2014-090160, Japanese Patent Publication No. 2015-041671

[0011] Therefore, the object of the present invention is to provide a substrate for mounting electronic devices that can keep electronic devices in a dry state by preventing moisture permeation, and can also prevent rust from occurring on the electrode foil.

[0012] According to the present invention, there is a substrate for mounting an electronic device having a metal foil and a protective resin layer, wherein the protective resin layer is provided on one surface of the metal foil, the other surface of the metal foil is the surface on which the electronic device is mounted, and a hygroscopic resin layer and an electrode foil are provided on the other surface of the metal foil in order from the other surface of the metal foil.

[0013] In the substrate for mounting electronic devices of the present invention, (1) the thickness of the electrode foil is 15 to 50 μm, (2) the conductivity of the electrode foil is 60 to 106%, (3) the electrode foil is formed from copper or aluminum, (4) the electrode foil is electrolytic copper foil, (5) both sides of the electrode foil are treated to prevent oxidation, (6) the surface of the electrode foil is treated to coarse graining, (7) the electrode foil is patterned, (8) the thickness of the metal foil is 5 to 20 μm, (9) the metal foil is formed from aluminum, (10) the protective resin layer is formed from polycarbonate resin, silicone resin, polyester resin, fluororesin, or acrylic resin, (11) the hygroscopic resin layer is formed from an olefin resin in which a desiccant is dispersed, (12) the desiccant is a type of desiccant that chemically captures moisture by reacting with water. (13) The protective resin layer is black; (14) The metal foil, the protective resin layer, the hygroscopic resin layer and the electrode foil are bonded together with an adhesive layer; (15) An inner resin layer is provided between the hygroscopic resin layer and the electrode foil, and / or between the hygroscopic resin layer and the metal foil; (16) The inner resin layer is formed from polyester resin, polyamide resin, olefin resin, or cyclic olefin resin; (17) The inner resin layer is black; (18) The metal foil, the protective resin layer, the hygroscopic resin layer, the inner resin layer and the electrode foil are bonded together with an adhesive layer; (19) The adhesive forming the adhesive layer is a dry laminate adhesive made from urethane resin or epoxy resin; (20) An ultraviolet shielding layer is provided on the surface of the protective resin layer opposite to the surface on which the electronic device is mounted; (21) The overall thickness is 75 to 300 μm. (22) The electrode foil has an adhesive layer formed from an adhesive on the side facing the electronic device; (23) The adhesive is made of an olefin resin or a cyclic olefin resin; (24) The electronic device mounting substrate is held in a roll-shaped package of the electronic device mounting substrate,(25) It is preferable that the roll-shaped packaging is sealed and contained in a packaging bag made of a barrier film having a heat-seal layer.

[0014] The substrate for mounting electronic devices of the present invention blocks the permeation of most moisture with a metal foil, and any trace amounts of moisture that penetrate through pinholes in the metal foil are absorbed by the hygroscopic resin layer. As a result, it is possible to prevent moisture from entering the device and electrode foil, keeping the device in a dry state for a long period of time, and also preventing rust from forming on the electrode foil.

[0015] Furthermore, when electrode foils are patterned, the side surfaces of the patterned areas within the electrode foil are particularly susceptible to rust because they are not treated with an anti-oxidation agent. However, the substrate for mounting electronic devices of the present invention has high moisture barrier properties, which prevents rust from occurring on the side surfaces of the patterned areas within the electrode foil.

[0016] A schematic cross-sectional view showing an example of the layer structure of the substrate for mounting electronic devices of the present invention. A schematic cross-sectional view in Figure 1, where the electrode foil is patterned. A schematic cross-sectional view showing another example of the layer structure of the substrate for mounting electronic devices of the present invention. A schematic cross-sectional view showing another example of the layer structure of the substrate for mounting electronic devices of the present invention. A schematic cross-sectional view in Figure 2, where an adhesive layer is provided. A schematic cross-sectional view in Figure 3, where an adhesive layer is provided. A schematic cross-sectional view in Figure 4, where an adhesive layer is provided.

[0017] Referring to Figures 1 to 7, the electronic device mounting substrate of the present invention, shown as 1 overall, has a metal foil 3 and a protective resin layer 5. The protective resin layer 5 is provided on one surface (the outer surface) of the metal foil 3, and the other surface of the metal foil 3 is the surface on which the electronic device is mounted. On the other surface of the metal foil 3, in order from the other surface of the metal foil 3, a hygroscopic resin layer 7 and an electrode foil 9 are provided. In Figure 1, an electrode foil 9 without patterning is provided, while in Figures 2 to 7, an electrode foil 9 with patterning is provided.

[0018] <Metal foil 3> Metal foil 3 has the role of blocking most of the moisture (water vapor) that tries to enter the device.

[0019] The material of the metal foil 3 is preferably aluminum, from the viewpoint of flexibility, ease of forming thin films, and cost reduction.

[0020] The thickness of the metal foil 3 is 5 to 20 μm, more preferably 6 to 20 μm, and particularly preferably 6 to 15 μm. Metal foil 3 with a thickness of less than 5 μm is difficult to manufacture. On the other hand, metal foil 3 with a thickness exceeding 20 μm has insufficient flexibility and becomes difficult to handle.

[0021] Here, flexibility (bending resistance) refers to the property of being flexible while being durable against tensile and compressive stresses. The thinner the metal foil 3, the better its flexibility. Also, since the amount of metal foil 3 used can be reduced as it becomes thinner, the overall manufacturing cost of the base material 1 can also be reduced.

[0022] However, it is generally known that the number of pinholes increases as the metal foil 3 becomes thinner. Therefore, when the metal foil 3 is thinner than when it is thicker, the amount of moisture that permeates through increases, and there is a risk that sufficient moisture barrier properties cannot be achieved. In this invention, a hygroscopic resin layer 7, described later, is provided on the electronic device side of the metal foil 3. This allows for the absorption of trace amounts of moisture that have permeated through the pinholes in the metal foil 3, thereby preventing moisture from permeating into the electronic device and keeping the electronic device dry. In other words, most of the moisture that tries to enter the device from the outside is blocked by the metal foil 3, but even trace amounts of moisture that have permeated through the pinholes in the metal foil 3 are absorbed by the hygroscopic resin layer 7. Thus, the hygroscopic resin layer 7 compensates for the decrease in moisture barrier properties caused by the thinness of the metal foil 3.

[0023] <Protective resin layer 5> The protective resin layer 5 is a layer provided on the side of the metal foil 3 opposite to the side where the electronic device is mounted (i.e., the outer surface side of the metal foil 3) in order to prevent scratches, holes, and oxidative degradation of the metal foil 3.

[0024] The protective resin layer 5 is formed using various resins known to the present day, but is generally preferably formed from olefin resins, cyclic olefin resins, silicone resins, polyimide resins, polyester resins, polyamide resins, polycarbonate resins, polyacrylonitrile resins, fluororesins, acrylic resins, etc., and is more preferably formed from polyester resin from the viewpoint of cost and mechanical strength. On the other hand, weather resistance can also be provided by forming it from polycarbonate resin, silicone resin, fluororesin, or acrylic resin.

[0025] The thickness of such a protective resin layer 5 is 12 to 200 μm, preferably 12 to 150 μm, and more preferably 12 to 100 μm. If the thickness of the protective resin layer 5 is less than 12 μm, scratches, holes, and oxidative degradation of the metal foil 3 may occur. If the thickness of the protective resin layer 5 exceeds 200 μm, it is excessively thick for protecting the metal foil 3, and manufacturing costs will increase unnecessarily.

[0026] The protective resin layer 5 described above can be obtained by extrusion molding or the like.

[0027] The protective resin layer 5 can be colored. When colored, it can provide aesthetic appeal and also light shielding to the inside of the substrate and the device. A colored protective resin layer 5 can be obtained by mixing a pigment into the resin or by adding an ink layer adjacent to it when molding the protective resin layer 5. In particular, when the electronic device mounting substrate 1 of the present invention is used as a backsheet for a solar cell, the color of the protective resin layer 5 is preferably black from the viewpoint of appearance.

[0028] <Moisture-absorbing resin layer 7> The moisture-absorbing resin layer 7 is a layer that absorbs trace amounts of moisture that have permeated through the pinholes in the metal foil 3, and is a layer in which a desiccant is dispersed in the resin. The moisture-absorbing resin layer 7 is provided on the side of the metal foil 3 that is on which the electronic device is mounted.

[0029] In the hygroscopic resin layer 7, a known inorganic or organic desiccant is used as the desiccant. Examples of inorganic desiccants include zeolite, alumina, activated carbon, clay minerals such as montmorillonite, silica gel, calcium oxide, barium oxide, calcium chloride, and magnesium sulfate. Examples of organic desiccants include anionic polymers or crosslinked products of partially neutralized anionic polymers. Examples of anionic polymers include those obtained by polymerizing or copolymerizing at least one anionic monomer, such as carboxylic acid monomers (e.g., (meth)acrylic acid and maleic anhydride), sulfonic acid monomers (e.g., vinyl halogenated sulfonic acid, styrene sulfonic acid, vinyl sulfonic acid), phosphonic acid monomers (e.g., vinyl phosphoric acid), and salts of these monomers, with other monomers.

[0030] In the present invention, from the viewpoint of being able to capture absorbed moisture without releasing it, a desiccant that chemically captures moisture by reacting with water is preferred over a desiccant that captures moisture by physical adsorption, such as zeolite or silica gel. As such a desiccant that exhibits chemical adsorption by reacting with water, calcium oxide and calcium chloride are suitably used.

[0031] Furthermore, the above-mentioned desiccant is preferably small in particle size, from the viewpoint of being able to be uniformly dispersed in the resin and having a large specific surface area. For example, it is preferable that the average primary particle diameter (D50) in volume, measured by laser diffraction scattering, is 20 μm or less. Typically, it is preferable that it is dispersed in the hygroscopic resin layer 7 in an amount of 5 to 80 parts by mass per 100 parts by mass of the matrix resin.

[0032] Furthermore, the resin in which the desiccant is dispersed (i.e., the resin matrix) is not particularly limited, and known thermoplastic resins can be used. However, generally, from the viewpoint of cost and ease of adhesion to other layers, olefin resins, such as low-density polyethylene, high-density polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, or random or block copolymers of α-olefins such as ethylene, propylene, 1-butene, and 4-methyl-1-pentene, or cyclic olefin copolymers, are preferably used. In the present invention, among the above olefin resins, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), and blends thereof are preferred in terms of relatively low hygroscopicity and preventing deactivation of the desiccant before use. Among these, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) are preferred.

[0033] Furthermore, the thickness of such a hygroscopic resin layer 7 is not particularly limited and may be set to an appropriate thickness depending on the size of the device to which this substrate is applied.

[0034] The hygroscopic resin layer 7 can be colored. Coloring can enhance the design and also provide light-blocking properties to the substrate. A colored hygroscopic resin layer 7 can be obtained by mixing a pigment into the resin during the molding process.

[0035] The hygroscopic resin layer 7 described above can be obtained by extrusion molding or the like.

[0036] <Electrode Foil 9> The electrode foil 9 is provided on the side of the hygroscopic resin layer 7 that is mounted on the electronic device, and functions as an electrode when connected to the electronic device.

[0037] The thickness of the electrode foil 9 is preferably 15 to 50 μm, more preferably 20 to 45 μm, and particularly preferably 25 to 40 μm. Electrode foil 9 with a thickness of less than 15 μm is difficult to manufacture. On the other hand, electrode foil 9 with a thickness exceeding 50 μm has insufficient flexibility and becomes difficult to handle.

[0038] The electrode foil 9 preferably has an conductivity of 60 to 106%, more preferably 61 to 104%, and particularly preferably 62 to 102%. If the conductivity of the electrode foil 9 is lower than 60%, the power generation efficiency of the electronic device may decrease and the power consumption may increase. It may also become necessary to increase the thickness of the electrode foil. On the other hand, it is technically difficult to make the conductivity of the electrode foil 9 higher than 106%.

[0039] The electrode foil 9 may be formed from any known metal material, but from the viewpoint of cost, conductivity, and ease of handling, it is preferable that it be formed from copper or aluminum.

[0040] When copper foil is used for the electrode foil 9, either rolled copper foil or electrolytic copper foil can be used, but from the viewpoint of cost, it is preferable to use electrolytic copper foil.

[0041] It is preferable that the electrode foil 9 is treated with an anti-oxidation treatment on both sides. The type of anti-oxidation treatment is not limited to this, but it is common to perform chromate treatment after nickel plating. By performing the anti-oxidation treatment, a rust prevention effect is achieved. Furthermore, if the coarsening treatment described later is performed, it is preferable to perform the anti-oxidation treatment on top of the coarsening treatment.

[0042] It is preferable that the electrode foil 9 has been subjected to a coarse-graining treatment on its surface. Coarse-graining treatment is a process in which coarse metal particles are locally deposited at multiple locations on the surface of the electrode foil 9, and by performing such a treatment, the anchoring effect can be enhanced. Generally, the coarse-graining treatment is performed by depositing coarse metal particles onto the electrode foil 9 by electrolysis. Furthermore, it is preferable that the surface subjected to this coarse-graining treatment is positioned to face the adhesive layer 13, which will be described later.

[0043] The electrode foil 9 is preferably patterned. By performing patterning, it can have the function as wiring of an electronic device. As the patterning method, known methods can be used, but it is common to perform it by methods such as die cutting, etching treatment, or laser treatment. In the examples shown in FIGS. 2 to 7, the electrode foil 9 is patterned and has the function as wiring of an electronic device by being insulated in the void portion.

[0044] Also, when the electrode foil 9 is patterned, the side surface portion 9a at the patterned portion in the electrode foil 9 is likely to rust because it is not subjected to an antioxidant treatment. However, the base material 1 for mounting an electronic device of the present invention has high moisture barrier properties, and the hygroscopic resin layer 7 absorbs the moisture remaining at the patterned portion, so that rusting can be prevented even at the side surface portion 9a at the patterned portion in the electrode foil 9.

[0045] <Inner resin layer 11> The inner resin layer 11 is a layer provided between the metal foil 3 and the electronic device and provided to impart insulation between the metal foil 3 and the electronic device. The inner resin layer 11 is provided between the hygroscopic resin layer 7 and the electrode foil 9 and / or between the hygroscopic resin layer 7 and the metal foil 3.

[0046] Figures 1 and 2 show the layer configuration when the inner resin layer 11 is provided on the electronic device side of the hygroscopic resin layer 7 (i.e., between the hygroscopic resin layer 7 and the electrode foil 9). In this case, the electrode foil 9 is provided on the electronic device mounting side surface of the inner resin layer 11 via an adhesive layer 13. Figure 3 shows the layer configuration when the inner resin layer 11 is provided on the outer surface side of the hygroscopic resin layer 7 (i.e., between the metal foil 3 and the hygroscopic resin layer 7). In this case, the electrode foil 9 is provided on the electronic device mounting side surface of the hygroscopic resin layer 7 via an adhesive layer 13. Figure 4 shows the layer configuration when the inner resin layer 11 is provided on both sides of the hygroscopic resin layer 7 (i.e., between the hygroscopic resin layer 7 and the electrode foil 9, and between the hygroscopic resin layer 7 and the metal foil 3). In this case, the electrode foil 9 is provided on the electronic device mounting side surface of the inner resin layer 11 via an adhesive layer 13. Although not shown in the diagram, if the inner resin layer 11 is not provided, the electrode foil 9 is provided on the surface of the hygroscopic resin layer 7 on the side where the electronic device is mounted, via an adhesive layer 13.

[0047] Such an inner resin layer 11 is formed from polyester resin, polyamide resin, polyimide resin, polycarbonate resin, polyacrylonitrile resin, olefin resin, cyclic olefin resin, etc., and is preferably formed from polyester resin, polyamide resin, olefin resin, or cyclic olefin resin. As for the polyester resin, polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) are particularly preferred from the viewpoint of cost, insulation, and heat resistance. Polyamide resin is also preferred for the same reason. When the inner resin layer 11 is provided on the electronic device side of the hygroscopic resin layer 7 and is formed from an olefin resin or a cyclic olefin resin, improved adhesion with adhesives and sealants for bonding to the electronic device can be expected.

[0048] The thickness of the inner resin layer 11 is 12 to 250 μm, preferably 12 to 200 μm, more preferably 12 to 150 μm. If the thickness of the inner resin layer 11 is less than 12 μm, the insulation between the metal foil 3 and the electronic device becomes insufficient, and there is a risk of energization. If the thickness of the inner resin layer 11 exceeds 250 μm, it is an excessive thickness for the insulation between the metal foil 3 and the electronic device, and the manufacturing cost increases unnecessarily.

[0049] The inner resin layer 11 can be colored. When colored, it can impart design properties and also impart light-shielding properties to the inside of the base material. When forming the inner resin layer 11, a colored inner resin layer 11 can be obtained by mixing a pigment into the resin or by adjacent an ink layer. In particular, when the base material 1 for mounting an electronic device of the present invention is used as a backsheet of a solar cell, the color of the inner resin layer 11 is preferably black from the viewpoint of appearance.

[0050] The inner resin layer 11 as described above is obtained by extrusion molding or the like.

[0051] <Adhesive layer 13> It is preferable that between the metal foil 3, the protective resin layer 5, the hygroscopic resin layer 7, and the electrode foil 9, which constitute the base material 1 for mounting an electronic device described above, are adhered by an adhesive layer 13. Further, when the base material 1 for mounting an electronic device has an inner resin layer 11, it is preferable that between the metal foil 3, the protective resin layer 5, the hygroscopic resin layer 7, the electrode foil 9, and the inner resin layer 11 are adhered by an adhesive layer 13.

[0052] As the adhesive for forming the adhesive layer 13 described above, an epoxy-based adhesive or a urethane-based adhesive known as a dry lamination adhesive is suitable.

[0053] Epoxy-based adhesive; The above epoxy-based adhesive is one that cures and adheres a liquid epoxy resin with an epoxy curing agent. Such an epoxy resin is a liquid resin having an epoxy group in the molecule, and is typically obtained by a reaction of epichlorohydrin with a phenol compound, an amine compound, a carboxylic acid, etc., or obtained by oxidizing an unsaturated compound such as butadiene with an organic peroxide, etc. Any type can be used.

[0054] Specific examples of epoxy adhesives, though not limited to these, include bisphenol A or bisphenol F epoxy resins, novolac epoxy resins, cyclic aliphatic epoxy resins, long-chain aliphatic epoxy resins, glycidyl ester epoxy resins, and glycidylamine epoxy resins. In the present invention, glycidylamine epoxy resins are particularly preferred because they can form an adhesive layer 13 with a high elastic modulus.

[0055] Furthermore, known epoxy curing agents such as amines, acid anhydrides, and polyamides can be used, but from the viewpoint of forming a coating film (adhesive layer 13) with a high elastic modulus and that can easily follow thermal shrinkage, amine-based curing agents, especially aromatic polyamines represented by metaphenylenediamine, are preferably used.

[0056] The ratio of epoxy resin to hardener should be set according to the epoxy equivalent content of the epoxy resin so that a sufficient cured film is formed.

[0057] Urethane adhesives; Urethane adhesives consist of a reaction product of polyisocyanate and polyol. These adhesives typically contain known curing catalysts such as amine-based catalysts, metal catalysts, or phosphate-modified compounds. The amount of curing catalyst is set according to the type of curing catalyst so that a dense cured film (adhesive layer 13) can be formed at a temperature and time that does not cause thermal deformation of the substrate resin.

[0058] Polyols used in the formation of polyurethane adhesives are compounds having two or more OH groups in one molecule, and typical examples include the following compounds: di-, tri-, tetra-, penta-, and hexa-hydroxy compounds; polyester polyols containing two or more OH groups in one molecule; polyether polyols containing two or more OH groups in one molecule; polycarbonate polyols containing two or more OH groups in one molecule; polycaprolactone polyols containing two or more OH groups in one molecule; and polyacrylic polyols containing two or more OH groups in one molecule. The most suitable polyol in this invention is a polyester polyol.

[0059] Furthermore, the polyisocyanates that react with the polyols are compounds that have two or more NCO groups in a single molecule. Specific examples, though not limited to these, include the following compounds. Aliphatic isocyanates such as ethylene diisocyanate, trimethylene diisocyanate, and tetramethylene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate, norbornane diisocyanate, bis(isocyanate methyl)cyclohexane, 2-isocyanate methyl-3-(3-isocyanate propyl)-5-isocyanate methyl-bicyclo[2,2,1]-heptane; aromatic isocyanates such as xylylene diisocyanate, bis(isocyanate ethyl)benzene, bis(isocyanate methyl)naphthalene, and bis(isocyanate methyl)diphenyl ether; sulfur-containing aliphatic isocyanates such as thiodiethyl diisocyanate; aliphatic sulfide isocyanates such as bis[2-(isocyanate methylthio)ethyl] sulfide; aromatic sulfide isocyanates such as diphenyl sulfide-2,4'-diisocyanate; Aromatic disulfide isocyanates such as diphenyl disulfide-4,4'-diisocyanate; aromatic sulfone isocyanates such as diphenyl sulfone-4,4'-diisocyanate; sulfonic acid ester isocyanates such as 4-methyl-3-isocyanate-benzenesulfonyl-4'-isocyanate-phenol ester; aromatic sulfonic acid amide isocyanates such as 4-methyl-3-isocyanate-benzenesulfonylanilide-3'-methyl-4'-isocyanate; sulfur-containing heterocyclic isocyanates such as thiophene-2,5-diisocyanate;

[0060] The polyisocyanates mentioned above are typically used in amounts such that the isocyanate groups (NCO groups) are approximately 0.8 to 1.2 moles per mole of hydroxyl groups present in the aforementioned polyol.

[0061] The epoxy adhesive and urethane adhesive described above are applied to a designated area using a volatile organic solvent such as hydrocarbon, alcohol, ketone, ester, or ether, and dried to form an adhesive layer 13. The adhesive layer 13 thus formed is usually cured by being held at a temperature of about 30 to 50°C for 24 hours or more.

[0062] The thickness of the adhesive layer 13 is 0.1 to 10 μm, preferably 2 to 6 μm. If the thickness of the adhesive layer 13 is less than 0.1 μm, the adhesion between layers may be insufficient. If the thickness of the adhesive layer 13 exceeds 10 μm, the adhesion between layers can be ensured, but the manufacturing cost will increase unnecessarily.

[0063] <Ultraviolet-blocking layer 15> An ultraviolet-blocking layer 15 can be provided on the surface of the protective resin layer 5 opposite to the surface on which the electronic device is mounted (i.e., the outer surface of the protective resin layer 5). This ultraviolet-blocking layer 15 has the role of preventing ultraviolet rays from penetrating into the substrate and the device by reflecting or absorbing ultraviolet rays.

[0064] The range of ultraviolet wavelengths reflected or absorbed by the ultraviolet-blocking layer 15 is 200 nm to 400 nm, preferably 250 nm to 400 nm, and particularly preferably 280 nm to 400 nm. The ultraviolet transmittance of the ultraviolet-blocking layer 15 is 0.1% to 20%, preferably 0.1% to 15%, and more preferably 0.1% to 10%. If the ultraviolet transmittance is less than 0.1%, the quality is excessive and the cost increases. On the other hand, if the ultraviolet transmittance exceeds 20%, the substrate or electronic device deteriorates.

[0065] The UV-blocking layer 15 can be molded from a general thermoplastic resin, but from the viewpoint of weather resistance and cost, it is preferable to form it from a resin such as polycarbonate resin, silicone resin, polyester resin, fluororesin, or acrylic resin. In the resin forming the UV-blocking layer 15, inorganic pigments such as carbon black, which absorbs ultraviolet rays, or titanium dioxide, which scatters ultraviolet rays, can be dispersed in the resin as UV shielding agents. In addition, when absorbing ultraviolet rays, additives such as benzotriazole, benzophenone, or triazine-based organic UV absorbers can be dispersed in the resin. When the UV-blocking layer 15 is formed from a resin, it is preferable that it is bonded to the protective resin layer 5 with an adhesive layer 13, particularly a dry laminate adhesive.

[0066] Furthermore, the ultraviolet-blocking layer 15 can also be formed by directly applying a paint to the surface of the protective resin layer 5. In this case, the transmission of ultraviolet rays to the device can be blocked by reflecting or absorbing all or part of the ultraviolet rays. Suitable paints for this purpose include fluorine-based, silicone-based, urethane-based, and acrylic-based paints.

[0067] <Adhesive Layer 17> Furthermore, when the base material 1 is used in an electronic device, an adhesive layer 17 can be provided by applying or attaching an adhesive to the side of the electrode foil 9 that is mounted on the electronic device, and then attaching it to the device surface. In this configuration, the moisture absorption capacity of the hygroscopic resin layer 7 allows moisture inside the device to be absorbed and dried through the adhesive layer 17. In addition, by providing the product in a form with an adhesive layer 17, the processing steps required by the customer can be reduced.

[0068] Examples of materials constituting the adhesive layer 17 include known pressure-sensitive adhesives such as acrylic, silicone, and butadiene-based adhesives; hot-melt adhesives such as ethylene-vinyl acetate copolymer resins, polyvinyl butyral, olefins, and cyclic olefins; UV-curing adhesives such as epoxy and acrylics; and thermosetting adhesives such as silicones. Among these, hot-melt adhesives are preferred because they do not require a drying process, and hot-melt adhesives formed from olefins or cyclic olefins are more preferred in terms of cost and ease of handling. The olefin or cyclic olefin may be copolymerized with vinyl acetate, methyl acrylate, methyl methacrylate, etc. The thickness of the adhesive layer 17 can be appropriately determined according to its application.

[0069] The adhesive layer 17 described above is positioned on the innermost surface of the electronic device mounting substrate 1 of the present invention, that is, in a position that faces the electronic device during use. Figures 5 to 7 show examples of layer configurations when the adhesive layer 17 is provided on the electronic device mounting substrate 1 of the present invention. The layer configurations in Figures 5 to 7 correspond to the layer configurations in Figures 2 to 4. In all cases, the adhesive layer 17 is formed on the surface of the electrode foil 9 that is on the side where the electronic device is mounted.

[0070] Furthermore, it is preferable that the adhesive layer 17 has through holes, and that these through holes are filled with a conductive material. The presence of the conductive material allows for an electrical connection between the electronic device and the electrode foil 9. In particular, when used as a backsheet for solar cells, the pattern of these through holes can be changed to allow for customization for each solar cell, which increases design flexibility and leads to a reduction in manufacturing costs.

[0071] <Manufacturing and Application of Substrate> The substrate 1 for mounting electronic devices having the layered structure described above is manufactured by bonding a metal foil 3, a pre-made protective resin layer 5, a hygroscopic resin layer 7, an inner resin layer 11, an electrode foil 9, and, if necessary, an ultraviolet-blocking layer 15, with an adhesive layer 13. The bonding operation can be carried out by appropriate means depending on the type of adhesive layer 13. For example, when bonding using a dry laminate adhesive, the substrate of the present invention can be obtained by applying a resin that forms the dry laminate adhesive to one or both surfaces of each layer and then heat-pressing them together. Furthermore, each layer may be pressed sequentially, or all layers may be pressed together at once.

[0072] The substrate 1 for mounting electronic devices obtained in this manner has an overall thickness of 75 to 300 μm, preferably 80 to 280 μm, and more preferably 85 to 270 μm. If the overall thickness of the substrate 1 is less than 75 μm, the overall strength of the substrate will be insufficient, which may lead to tearing, punctures, etc. On the other hand, if the overall thickness of the substrate 1 exceeds 300 μm, sufficient flexibility cannot be obtained, making it difficult to handle. Note that the thickness of the adhesive layer 17 is not included in the overall thickness of the substrate 1 described here.

[0073] As described above, it is preferable that the substrate 1 for mounting electronic devices of the present invention has an inner resin layer 11 between the hygroscopic resin layer 7 and the electrode foil 9, and / or between the hygroscopic resin layer 7 and the metal foil 3. As a result, at least an inner resin layer 11 is present between the metal foil 3 and the electrode foil 9, so that current cannot be conducted between the metal foil 3 and the electrode foil 9, while the metal foil 3 and the hygroscopic resin layer 7 can provide a barrier against moisture entering from the outside.

[0074] Furthermore, if necessary, the electrode foil 9 is patterned after lamination, and after the patterning process, an adhesive is applied to form an adhesive layer 17. In addition, through holes are formed in the adhesive layer 17 according to the formed patterned shape, and conductive resin is filled in, electrically connecting the electrode foil 9 and the electronic device.

[0075] The electronic device mounting substrate 1 of the present invention is preferably held in a roll-shaped package, wound into a roll. Furthermore, such a roll-shaped package is preferably sealed and contained in a packaging bag made of a barrier film equipped with a heat-seal layer. Examples of such barrier films include plastic films equipped with a metal vapor-deposited film or metal foil. When a metal vapor-deposited film is used, an aluminum vapor-deposited film is preferred, and when a metal foil is used, aluminum foil is preferred. By placing a desiccant in such a package and packaging and storing the roll-shaped package, the absorption of moisture from the air is suppressed, and a decrease in the moisture absorption performance of the hygroscopic resin layer 7 can be prevented. Furthermore, by sealing the package with the air removed from the bag to prevent absorption of moisture from the atmosphere, it may be possible to confirm from the outside if the bag is damaged and the sealed state is broken.

[0076] The electronic device is not particularly limited, and the substrate of the present invention can be applied to all electronic devices that are undesirable due to charge leakage caused by the presence of moisture, such as organic EL elements, solar cells, and touch panels.

[0077] Furthermore, since the electronic device mounting substrate 1 of the present invention has a metal foil 3, it can be used on the side of the above-mentioned device where light transmittance is not required, for example, a non-light-receiving surface such as the backsheet of a solar cell, a non-light-emitting surface of an organic electroluminescent element, or the side surface of various devices.

[0078] In particular, when used in solar cells, it is especially preferable to use it in back-contact type solar cells. A back-contact type solar cell is a type of solar cell in which the electrodes of the solar cell are concentrated on the back side. This reduces the wiring on the light-receiving surface and increases the amount of transmitted light, resulting in a solar cell with excellent power generation efficiency. Here, in a normal solar cell, electrodes are placed on both the light-receiving side and the back side. On the other hand, in a back-contact type solar cell, the electrodes are concentrated on the back side. That is, because the distance between all electrodes and the back sheet is short, by using the electronic device mounting substrate 1 of the present invention, high moisture barrier properties can be achieved, and electrode deterioration and rust can be more effectively prevented. Therefore, by using the electronic device mounting substrate 1 of the present invention as a back sheet for a back-contact type solar cell, a longer lifespan for the solar cell can be expected.

[0079] (Experimental Examples 1-8) Aluminum foil of the thickness shown in Table 1 was used as the metal foil. A coating solution in which a urethane-based adhesive resin was dissolved or dispersed was prepared as a dry laminating adhesive. This coating solution was applied to the aluminum foil and dried to form an adhesive layer. A 25 μm thick PET resin film obtained by extrusion molding was heat-pressed onto this adhesive layer as a protective resin layer. Next, the coating solution was applied to the surface of the metal foil opposite to the surface to which the protective resin layer was pressed, and dried to form an adhesive layer. Then, an olefin resin in which a desiccant was dispersed at 25 phr in the resin matrix was extruded onto this adhesive layer as a hygroscopic resin layer and heat-pressed. Furthermore, the coating solution was applied to the surface of the hygroscopic resin layer and dried to form an adhesive layer. Finally, the electrode foils shown in Table 1 were heat-pressed onto the surface as electrode foils to produce substrates A to H shown in Table 1. Substrates A to H were produced by changing the thickness and type of electrode foil.

[0080] (Experimental Example 9) Substrate I shown in Table 1 was prepared in the same manner as in Experimental Example 2, except that a hygroscopic resin layer was not provided.

[0081] (Experimental Example 10) Substrate J shown in Table 1 was prepared in the same manner as in Experimental Example 2, except that an inner resin layer consisting of a 25 μm thick PET resin film was provided between the hygroscopic resin layer and the electrode foil.

[0082] (Experimental Example 11) A substrate K shown in Table 1 was prepared in the same manner as in Example 2, except that an inner resin layer made of a PET resin film with a thickness of 25 μm was provided between the metal foil and the hygroscopic resin layer.

[0083] (Experimental Example 12) A substrate L shown in Table 1 was prepared in the same manner as in Experimental Example 2, except that patterning was applied to the electrode foil by wet etching.

[0084] (Experimental Example 13) Substrate M shown in Table 1 was prepared in the same manner as in Experimental Example 9, except that patterning was applied to the electrode foil by wet etching.

[0085]

[0086] (Evaluation Details) <Electrode Foil Corrosion Confirmation Test (Edge Direction)> For substrates A to M obtained in Experimental Examples 1 to 13, the electrode foil side and the surface of the glass substrate were bonded together using an olefin-based hot melt adhesive (thickness 200 μm) to create a 10 cm x 10 cm evaluation cell. A vacuum heating laminator was used for bonding. The evaluation cell was stored in a constant temperature and humidity chamber at 85°C and 85% RH for 5 days. The presence or absence of discoloration of the electrode foil at the cell edge (within a 1 cm range from the edge) was observed visually from the glass substrate side. The evaluation criteria are as follows. The results are shown in Table 2. <Evaluation Criteria> ○: No discoloration of the electrode foil was observed at all ×: Discoloration of the electrode foil was observed within a range of 5 mm from the cell edge ××: Discoloration of the electrode foil was observed beyond a range of 5 mm from the edge

[0087] <Flexibility Test (Bending Test)> Substrates A to M obtained in Experimental Examples 1 to 13 were subjected to a bending test of 10,000 times in both bending directions with a diameter of 5 mm using a benchtop durability testing machine (manufactured by Yuasa System Equipment Co., Ltd.) under conditions of 23°C and 50% RH, and the presence or absence of creases was checked. The evaluation criteria are as follows. The results are shown in Table 2. <Evaluation Criteria> ○: No creases ×: Creases present

[0088] <Adhesion Test (T-Type Peel Test)> For substrates A to M obtained in Experimental Examples 1 to 13, two substrates were bonded together on their electrode foil sides using an olefin-based hot melt adhesive (200 μm) to prepare samples for the T-type peel test. A vacuum heating laminator was used for bonding. The T-type peel test samples were cut into 100 mm x 15 mm strips, and a T-type peel test was performed using a tensile testing machine at a tensile speed of 300 mm / min (N=3). The average strength at this time was defined as the adhesion strength. The evaluation criteria are as follows. The results are shown in Table 2. <Evaluation Criteria> ◎: 30 (N / 15 mm) or more ○: 2 (N / 15 mm) or more, less than 30 (N / 15 mm) ×: Less than 2 (N / 15 mm)

[0089]

[0090] 1: Substrate for mounting electronic devices 3: Metal foil 5: Protective resin layer 7: Moisture-absorbing resin layer 9: Electrode foil 11: Inner resin layer 13: Adhesive layer 15: UV-blocking layer 17: Adhesive layer

Claims

1. A substrate for mounting an electronic device, comprising a metal foil and a protective resin layer, wherein the protective resin layer is provided on one surface of the metal foil, the other surface of the metal foil is the surface on which the electronic device is mounted, and a hygroscopic resin layer and an electrode foil are provided on the other surface of the metal foil in order from the other surface of the metal foil.

2. The substrate for mounting electronic devices according to claim 1, wherein the thickness of the electrode foil is 15 to 50 μm.

3. The substrate for mounting electronic devices according to claim 1, wherein the conductivity of the electrode foil is 60 to 106%.

4. The substrate for mounting electronic devices according to claim 1, wherein the electrode foil is formed of copper or aluminum.

5. The substrate for mounting electronic devices according to claim 4, wherein the electrode foil is an electrolytic copper foil.

6. The substrate for mounting electronic devices according to claim 4, wherein both sides of the electrode foil are treated to prevent oxidation.

7. The substrate for mounting electronic devices according to claim 4, wherein the surface of the electrode foil is subjected to a coarse-graining treatment.

8. The substrate for mounting an electronic device according to claim 1, wherein the electrode foil is patterned.

9. The substrate for mounting electronic devices according to claim 1, wherein the thickness of the metal foil is 5 to 20 μm.

10. The substrate for mounting electronic devices according to claim 1, wherein the metal foil is formed from aluminum.

11. The substrate for mounting electronic devices according to claim 1, wherein the protective resin layer is formed from polycarbonate resin, silicone resin, polyester resin, fluororesin, or acrylic resin.

12. The substrate for mounting electronic devices according to claim 1, wherein the hygroscopic resin layer is formed from an olefin resin in which a desiccant is dispersed.

13. The substrate for mounting electronic devices according to claim 12, wherein the desiccant is a type of desiccant that chemically captures moisture by reacting with water.

14. The substrate for mounting electronic devices according to claim 1, wherein the protective resin layer is black.

15. The substrate for mounting an electronic device according to claim 1, wherein the metal foil, the protective resin layer, the hygroscopic resin layer, and the electrode foil are bonded together with an adhesive layer.

16. The substrate for mounting an electronic device according to claim 1, wherein an inner resin layer is provided between the hygroscopic resin layer and the electrode foil, and / or between the hygroscopic resin layer and the metal foil.

17. The substrate for mounting electronic devices according to claim 16, wherein the inner resin layer is formed from a polyester resin, a polyamide resin, an olefin resin, or a cyclic olefin resin.

18. The substrate for mounting electronic devices according to claim 16, wherein the inner resin layer is black.

19. The substrate for mounting an electronic device according to claim 16, wherein the metal foil, the protective resin layer, the hygroscopic resin layer, the inner resin layer, and the electrode foil are bonded together with an adhesive layer.

20. The substrate for mounting electronic devices according to claim 15 or 19, wherein the adhesive forming the adhesive layer is a dry laminate adhesive made from a urethane resin or an epoxy resin.

21. The substrate for mounting an electronic device according to claim 1, wherein an ultraviolet shielding layer is provided on the surface of the protective resin layer opposite to the surface on which the electronic device is mounted.

22. The substrate for mounting electronic devices according to claim 1, wherein the overall thickness is 75 to 300 μm.

23. The substrate for mounting electronic devices according to claim 1, wherein an adhesive layer formed from an adhesive is provided on the side of the electrode foil on which the electronic device is mounted.

24. The substrate for mounting electronic devices according to claim 23, wherein the adhesive is formed from an olefin resin or a cyclic olefin resin.

25. A roll-shaped packaging of an electronic device mounting substrate, wherein the electronic device mounting substrate described in claim 1 is wound and held in a roll shape.

26. The roll-shaped packaging according to claim 25, which is sealed and contained in a packaging bag made of a barrier film having a heat-seal layer.

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