Coating agents for electronic components, and electronic components

Abstract

The present invention provides a coating agent for electronic components that can enhance the thermal insulation properties of the resulting coating layer. [Solution] The coating agent for electronic components according to the present invention is a coating agent used for electronic components, comprising a binder and a foam stabilizer, wherein the binder comprises a thermoplastic resin, a thermosetting compound, or a photocurable compound, and the volume occupied by bubbles in 100% by volume of the coating layer formed by the coating agent is 10% by volume or more.

Description

[Technical Field]

[0001] The present invention relates to a coating agent for electronic components used to form a coating layer in electronic components. The present invention also relates to an electronic component having a coating layer. [Background technology]

[0002] Electronic components, in which semiconductor elements and other electronic elements such as connectors are mounted on a circuit board, are widely used. These electronic components are sometimes sealed by injection molding with resin to obtain an electronic component module. Generally, the circuit board and the electronic components are electrically connected by solder. Furthermore, to protect the electronic components from moisture and prevent whisker formation and short circuits due to oxidation of the circuit on the board, a coating layer formed by a coating agent is placed on at least a portion of the surface of the electronic components.

[0003] For example, Patent Document 1 below discloses an in-vehicle control device comprising a circuit board, electronic components mounted on the circuit board, solder that electrically connects the terminals of the electronic components to the circuit board, and a coating film that protects at least a portion of the circuit board. In the above in-vehicle control device, the coating film covers the terminals and the solder, and the loss modulus of elasticity of the coating film at 125°C is 1.0 × 10⁻⁶. 5 It is Pa or higher. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] WO2017 / 038343A1 [Overview of the project] [Problems that the invention aims to solve]

[0005] The above-mentioned electronic component can be manufactured, for example, by placing a coating agent on the surface of a circuit board or the like in the electronic component, and then curing the coating agent to form a coating layer.

[0006] However, conventional coating agents may not be able to sufficiently improve the thermal insulation of the resulting coating layer. If the thermal insulation of the coating layer is insufficient, heat can easily be transferred through the coating layer to the solder joints on the circuit board during the fabrication of electronic component modules, which can cause the solder joints to partially remelt. When the solder joints remelt, a problem arises in that a poor connection occurs between the solder joints and the circuit board.

[0007] The object of the present invention is to provide a coating agent for electronic components that can improve the thermal insulation properties of the resulting coating layer, and an electronic component using the above-mentioned coating agent for electronic components. Another object of the present invention is to provide an electronic component that can improve the thermal insulation properties of the coating layer. [Means for solving the problem]

[0008] This specification discloses the following coatings for electronic components and electronic components.

[0009] Item 1. A coating agent for electronic components, comprising a binder and a foam stabilizer, wherein the binder comprises a thermoplastic resin, a thermosetting compound, or a photocurable compound, and the volume occupied by bubbles in 100% by volume of the coating layer formed by the coating agent is 10% by volume or more.

[0010] Item 2. The coating agent for electronic components according to Item 1, wherein the content of the foam stabilizer is 0.5% by weight or more and 5.0% by weight or less in 100% by weight of the coating agent.

[0011] Item 3. A coating agent for electronic components according to item 1 or 2, comprising particles.

[0012] Item 4. The coating agent for electronic components according to item 3, wherein the particles are hollow particles.

[0013] Item 5. The coating agent for electronic components according to item 3 or 4, wherein the specific gravity of the particles is 0.60 or less.

[0014] Item 6. The coating agent for electronic components according to any one of items 3 to 5, wherein the content of the particles in 100% by weight of the coating agent is 3.0% by weight or less.

[0015] Item 7. The coating agent for electronic components according to any one of items 1 to 6, wherein the binder contains a photocurable compound.

[0016] Item 8. The coating agent for electronic components according to any one of items 1 to 7, which is used to form a coating layer that coats the solder portion in an electronic component including a circuit board, an electronic element mounted on the circuit board, and a solder portion that electrically connects the circuit board and the electronic element.

[0017] Item 9. An electronic component including a circuit board, an electronic element mounted on the circuit board, and a solder portion that electrically connects the circuit board and the electronic element, further including a coating layer, wherein the coating layer coats the solder portion, and the material of the coating layer is the coating agent for electronic components according to any one of items 1 to 8.

[0018] Item 10. An electronic component including a circuit board, an electronic element mounted on the circuit board, and a solder portion that electrically connects the circuit board and the electronic element, further including a coating layer, wherein the coating layer coats the solder portion, and the volume occupied by bubbles in 100% by volume of the coating layer is 10% by volume or more.

Advantages of the Invention

[0019] The coating agent for electronic components according to the present invention is a coating agent used for electronic components. The coating agent for electronic components according to the present invention comprises a binder and a foam stabilizer, wherein the binder comprises a thermoplastic resin, a thermosetting compound, or a photocurable compound. In the coating agent for electronic components according to the present invention, the volume occupied by bubbles in 100% by volume of the coating layer formed by the coating agent is 10% by volume or more. Because the coating agent for electronic components according to the present invention has the above configuration, the heat insulation properties of the resulting coating layer can be improved.

[0020] The electronic component according to the present invention comprises a circuit board, an electronic element mounted on the circuit board, and a solder joint that electrically connects the circuit board and the electronic element. The electronic component according to the present invention further comprises a coating layer. In the electronic component according to the present invention, the coating layer coats the solder joint, and the volume occupied by air bubbles in 100% by volume of the coating layer is 10% by volume or more. Because the electronic component according to the present invention is provided with the above configuration, the heat insulation properties of the coating layer can be improved. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 is a schematic cross-sectional view showing an electronic component using a coating agent for electronic components according to one embodiment of the present invention. [Modes for carrying out the invention]

[0022] The details of the present invention will be described below.

[0023] (Coating agent for electronic components) The coating agent for electronic components according to the present invention (hereinafter sometimes referred to as "coating agent") is a coating agent used for electronic components. The coating agent for electronic components according to the present invention comprises a binder and a foam stabilizer, wherein the binder comprises a thermoplastic resin, a thermosetting compound, or a photocurable compound. In the coating agent for electronic components according to the present invention, the volume occupied by bubbles in 100% by volume of the coating layer formed by the coating agent is 10% by volume or more.

[0024] Conventional coating agents may not be able to sufficiently improve the thermal insulation of the resulting coating layer. If the thermal insulation of the coating layer is insufficient, heat (for example, heat from the molten resin during injection molding) can easily be transferred through the coating layer to the solder joints on the circuit board during the manufacturing of electronic component modules, which can cause the solder joints to partially remelt. When the solder joints remelt, a problem arises in that a connection failure occurs between the solder joints and the circuit board.

[0025] In contrast, the coating agent for electronic components according to the present invention has the above configuration, which makes it possible to improve the heat insulation properties of the resulting coating layer. As a result, it is possible to suppress the occurrence of connection failures between the soldered part and the circuit board in electronic components due to partial remelting of the soldered part.

[0026] The coating agent for electronic components according to the present invention makes it possible to prevent the solder joint from remelting easily in electronic components, even when injection molding is performed using an electronic component having a coating layer formed with the above coating agent and a resin, thereby suppressing connection failures between the solder joint and the circuit board (damage to the electronic component). The coating agent for electronic components according to the present invention can effectively suppress connection failures between the solder joint and the circuit board (damage to the electronic component) caused by heat conduction from the resin used in injection molding (resin for sealing the electronic component) in electronic components.

[0027] Furthermore, in order to lower the thermal conductivity of the resulting coating layer, 3% or more hollow particles may be added to 100% by weight of the coating agent. However, adding 3% or more hollow particles to 100% by weight of the coating agent presents challenges in terms of the effort required to add the hollow particles and the increased manufacturing costs.

[0028] In contrast, the coating agent for electronic components according to the present invention has the above configuration, making it possible to eliminate the inclusion of hollow particles in the coating agent for electronic components or to reduce the amount of hollow particles contained in the coating agent for electronic components. As a result, compared to the case in which a large amount of hollow particles are added to the coating agent for electronic components, the workability when manufacturing the coating agent for electronic components is improved and manufacturing costs can be reduced.

[0029] The above-mentioned coating agent is a coating agent used for electronic components. The above-mentioned coating agent is preferably used to coat electronic components. The above-mentioned coating agent is preferably used to form a coating layer that coats the soldered portion in an electronic component. In particular, the above-mentioned coating agent is preferably used to form a coating layer that coats the soldered portion in an electronic component comprising a circuit board, an electronic element mounted on the circuit board, and a soldered portion that electrically connects the circuit board and the electronic element.

[0030] The viscosity of the above coating agent at 25°C is preferably 50 mPa·s or more, more preferably 60 mPa·s or more, even more preferably 100 mPa·s or more, preferably 3000 mPa·s or less, more preferably 2000 mPa·s or less, even more preferably 1000 mPa·s or less, and particularly preferably 500 mPa·s or less. When the viscosity of the above coating agent at 25°C is above the lower limit and below the upper limit, the coating agent can be applied with a uniform thickness, and the heat insulation properties of the resulting coating layer can be further enhanced.

[0031] The viscosity of the above coating agent at 25°C can be measured using an E-type viscometer (for example, "TVE22L" manufactured by Toki Sangyo Co., Ltd.) under the conditions of 25°C and 5 rpm.

[0032] The volume occupied by bubbles in 100% by volume of the coating layer formed by the above coating agent (bubble volume ratio in the coating layer) is 10% by volume or more. Preferably, the bubble volume ratio in the above coating layer is 12% by volume or more, more preferably 15% by volume or more, even more preferably 18% by volume or more, preferably 40% by volume or less, more preferably 35% by volume or less, and even more preferably 30% by volume or less. If the bubble volume ratio in the above coating layer is above the lower limit, the heat insulation properties of the coating layer can be further enhanced, and damage to electronic components can be further suppressed. If the bubble volume ratio in the above coating layer is below the upper limit, the coating layer can be formed more uniformly.

[0033] In the coating agent according to the present invention, the volume fraction of bubbles in the coating layer can be measured, for example, by the following method. A coating layer is formed using the coating agent. The coating layer is cut to an arbitrary size (for example, 100 mm in length, 100 mm in width, and 0.3 mm in thickness) to prepare a test specimen. The test specimen is weighed in air (W1). Next, the test specimen is immersed in a working fluid at a constant temperature t (25°C). After the test specimen reaches the constant temperature t, the test specimen is weighed in the working fluid by a load exchange mechanism (W2). Water is used as the working fluid.

[0034]

number

[0035] ρ t : Density of the test specimen at temperature t (g / cm³) 3 ) W1: Weighing value of the test specimen in air (g) W2: Weighing value (g) of the test specimen in the working fluid. ρ s: Density of the working liquid at temperature t (g / cm 3 ) ρ air : Density of air (g / m 3 )

[0036] Next, the bubble volume fraction in the coating layer is calculated based on the following formula.

[0037] Bubble volume fraction in the coating layer (%) = 100 - (ρ t / ρ * 100)

[0038] ρ t : Density of the test piece at temperature t (g / cm 3 ) ρ: Density of the test piece without bubbles (g / cm 3 )

[0039] The density of the test piece without bubbles for obtaining ρ can be measured in the same manner as the density of the test piece with bubbles for obtaining ρ. The test piece without bubbles can be produced using a coating agent without bubbles. The coating agent without bubbles is produced in the same manner as the coating agent with bubbles, except that it does not contain bubbles. The compositions of the above coating agent with bubbles and the above coating agent without bubbles are the same. In order to obtain the above coating agent without bubbles, the stirring conditions during the production of the coating agent can be adjusted.

[0040] ​​In the coating agent according to the present invention, the method for forming the coating layer when measuring the volume fraction of bubbles in the coating layer is not particularly limited. If the coating agent contains a thermoplastic resin as a binder, the coating layer may be formed by drying the coating agent after application. If the coating agent contains a thermosetting compound as a binder, the coating layer may be formed by curing the coating agent by heating after application. If the coating agent contains a photocurable compound as a binder, the coating layer may be formed by curing the coating agent by irradiating it with light after application. When applying the coating agent, it is preferable to apply the coating layer in such a way that the state of bubbles contained in the coating agent does not change.

[0041] Methods for adjusting the volume ratio of bubbles in the above-mentioned coating layer include the following: adjusting the amount of bubbles in the coating agent; selecting the type of foam stabilizer in the coating agent; adjusting the amount of foam stabilizer in the coating agent; and adjusting the stirring time of the coating agent materials when preparing the coating agent.

[0042] The above coating agent preferably contains air bubbles. The method for incorporating air bubbles into the above coating agent is not particularly limited. The above coating agent may contain air bubbles because the coating agent material contains a foaming agent, may contain air bubbles by injecting gas during the preparation of the coating agent, or may contain air bubbles by stirring the coating agent material during the preparation of the coating agent. A stirrer (for example, AS ONE's "Pencil Mixer") may be used for the stirring.

[0043] The stirring speed of the coating agent material is not particularly limited. Preferably, the stirring speed of the coating agent material is 5000 rpm or more, more preferably 6000 rpm or more, even more preferably 7000 rpm or more, preferably 15000 rpm or less, more preferably 13000 rpm or less, and even more preferably 10000 rpm or less. When the stirring speed of the coating agent material is above the lower limit and below the upper limit, bubbles can be efficiently incorporated into the coating agent.

[0044] The stirring time of the coating agent materials is not particularly limited. Preferably, the stirring time of the coating agent materials is 60 seconds or more, more preferably 100 seconds or more, even more preferably 300 seconds or more, preferably 6000 seconds or less, more preferably 5000 seconds or less, and even more preferably 3000 seconds or less. When the stirring time of the coating agent materials is above the lower limit and below the upper limit, air bubbles can be efficiently incorporated into the coating agent.

[0045] The components used in the coating agent for electronic components according to the present invention will be described below. In the following description, "(meth)acrylic" means either or both "acrylic" and "methacrylic," "(meth)acryloyl" means either or both "acryloyl" and "methacryloyl," and "(meth)acrylate" means either or both "acrylate" and "methacrylate."

[0046] <Binder> The above binder comprises a thermoplastic resin, a thermosetting compound, or a photocurable compound. The above binder may contain a thermoplastic resin, a thermosetting compound, or a photocurable compound. Only one type of the above binder may be used, or two or more types may be used in combination.

[0047] From the viewpoint of increasing the curing speed of the above coating agent, the binder preferably contains a thermosetting compound or a photocurable compound, and more preferably contains a photocurable compound.

[0048] The viscosity of the binder at 25°C is preferably 50 mPa·s or more, more preferably 60 mPa·s or more, even more preferably 100 mPa·s or more, preferably 3000 mPa·s or less, more preferably 2000 mPa·s or less, even more preferably 1000 mPa·s or less, and particularly preferably 500 mPa·s or less. When the viscosity of the binder at 25°C is above the lower limit and below the upper limit, the viscosity of the coating agent can be well adjusted, a coating layer of uniform thickness can be well formed, and the heat insulation properties of the resulting coating layer can be further enhanced.

[0049] The viscosity of the above binder at 25°C can be measured using an E-type viscometer (for example, "TVE22L" manufactured by Toki Sangyo Co., Ltd.) under the conditions of 25°C and 5 rpm.

[0050] [Thermoplastic resin] The thermoplastic resin described above is not particularly limited. From the viewpoint of further improving the smoothness of the surface of the coating layer, if the binder contains the thermoplastic resin, it is preferable that the thermoplastic resin is not included in particulate form.

[0051] Examples of the thermoplastic resins mentioned above include synthetic resins and aqueous emulsion resins. Only one type of thermoplastic resin may be used, or two or more types may be used in combination.

[0052] Examples of the above-mentioned thermoplastic resins (synthetic resins) include polyolefin resins, polyamide resins, polycarbonate resins, polystyrene resins, polyester resins, and vinyl chloride resins.

[0053] From the viewpoint of improving the insulation resistance of the coating agent to electronic components, the thermoplastic resin preferably contains a polyolefin resin, and more preferably contains a polyolefin elastomer.

[0054] Examples of the above-mentioned polyolefin elastomers include copolymers of propylene and α-olefins; α-olefin polymers; ethylene-propylene rubbers such as ethylene-propylene rubber (EPM) and ethylene-propylene-diene rubber (EPDM); and chlorosulfonated polyethylene (CSM).

[0055] Examples of the above-mentioned aqueous emulsion resins include silicone (meth)acrylic emulsion resins, urethane emulsion resins, and (meth)acrylic emulsion resins.

[0056] When the binder contains the thermoplastic resin, the content of the thermoplastic resin in 100% by weight of the coating agent is preferably 0.7% by weight or more, more preferably 5.0% by weight or more, even more preferably 10.0% by weight or more, preferably 20.0% by weight or less, more preferably 19.0% by weight or less, even more preferably 18.0% by weight or less, and particularly preferably 17.0% by weight or less. When the content of the thermoplastic resin is above the lower limit and below the upper limit, the heat insulation properties of the resulting coating layer can be further enhanced, and the heat insulation properties can be made uniform throughout the entire coating layer.

[0057] [solvent] When the binder contains the thermoplastic resin, the coating agent preferably contains a solvent. The solvent is a solvent that dissolves the thermoplastic resin. The solvent is capable of dissolving the thermoplastic resin. In the coating agent, the thermoplastic resin is preferably included in a dissolved state in the solvent. The solvent also preferably functions as a dispersion medium for particles, as described later.

[0058] The above solvent can be appropriately selected and used, taking into consideration the solubility of the thermoplastic resin, the rate of evaporation, the dispersibility of hollow particles, and compatibility with foam stabilizers, etc.

[0059] Examples of the solvents mentioned above include water and organic solvents. Only one of these solvents may be used, or two or more may be used.

[0060] Examples of the above-mentioned organic solvents include acetone, methyl ethyl ketone, alkylcyclohexane, cyclohexene, ethylene glycol, propylene glycol, methyl alcohol, ethyl alcohol, isopropyl alcohol, butanol, benzene, toluene, xylene, ethyl acetate, and butyl acetate.

[0061] From the viewpoint of increasing the solubility of the polyolefin resin and further enhancing the heat insulation properties of the resulting coating layer, the solvent preferably contains an aliphatic hydrocarbon having 1 to 12 carbon atoms, and more preferably contains methylcyclohexane. In particular, the use of these preferred solvents is effective when the thermoplastic resin contains the polyolefin resin.

[0062] From the viewpoint of further improving the thermal insulation properties of the resulting coating layer, the solvent preferably contains toluene or alkylcyclohexane, and more preferably contains toluene or methylcyclohexane.

[0063] From the viewpoint of further improving the heat insulation properties of the resulting coating layer, the boiling point of the solvent is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. When the boiling point of the solvent is below the upper limit, the coating agent can be dried quickly and the coating layer formed while suppressing adverse effects on the electronic elements mounted on the circuit board. The boiling point of the solvent may be 50°C or higher, 60°C or higher, 70°C or higher, 80°C or higher, or 100°C or higher. When the boiling point of the solvent is above the lower limit, unintended volatilization of the solvent can be suppressed, and the handling of the coating agent can be improved.

[0064] Of the total 100% by weight of the thermoplastic resin and the solvent, the content of the thermoplastic resin is preferably 2.0% by weight or more, more preferably 6.0% by weight or more, even more preferably 11.0% by weight or more, preferably 20.0% by weight or less, more preferably 19.5% by weight or less, even more preferably 19.0% by weight or less, and particularly preferably 18.0% by weight or less. When the content of the thermoplastic resin is above the lower limit and below the upper limit, the heat insulation properties of the resulting coating layer can be further enhanced, and the heat insulation properties can be made uniform throughout the entire coating layer.

[0065] [Thermosetting compound] Examples of the above-mentioned thermosetting compounds include styrene compounds, phenoxy compounds, oxetane compounds, epoxy compounds, episulfide compounds, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. The above-mentioned thermosetting compounds may be used individually or in combination of two or more.

[0066] From the viewpoint of improving the insulation resistance of the coating agent to electronic components, the thermosetting compound preferably contains an epoxy compound or an episulfide compound, and more preferably contains an epoxy compound.

[0067] Examples of the epoxy compounds mentioned above include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, phenol novolac type epoxy compounds, biphenyl type epoxy compounds, biphenyl novolac type epoxy compounds, biphenol type epoxy compounds, naphthalene type epoxy compounds, fluorene type epoxy compounds, phenol aralkyl type epoxy compounds, naphthol aralkyl type epoxy compounds, dicyclopentadiene type epoxy compounds, anthracene type epoxy compounds, epoxy compounds having an adamantane skeleton, epoxy compounds having a tricyclodecane skeleton, naphthylene ether type epoxy compounds, and epoxy compounds having a triazine core as their skeleton. These epoxy compounds may be used individually or in combination of two or more.

[0068] From the viewpoint of improving the insulation resistance of the coating agent to electronic components, it is more preferable that the thermosetting compound contains a phenolic resin.

[0069] When the binder contains the thermosetting compound, the content of the thermosetting compound in 100% by weight of the coating agent is preferably 20% by weight or more, more preferably 40% by weight or more, even more preferably 50% by weight or more, preferably 99% by weight or less, more preferably 98% by weight or less, and even more preferably 97% by weight or less. When the content of the thermosetting compound is above the lower limit, air bubbles can be well incorporated into the coating layer, and the thermal conductivity of the coating layer can be further reduced. When the content of the thermosetting compound is below the upper limit, the time required for stirring can be minimized, so a coating layer can be formed with good workability.

[0070] When the thermosetting compound contains the epoxy compound, the content of the epoxy compound in 100% by weight of the coating agent is preferably 20% by weight or more, more preferably 40% by weight or more, even more preferably 50% by weight or more, preferably 99% by weight or less, more preferably 98% by weight or less, and even more preferably 97% by weight or less. When the content of the epoxy compound is above the lower limit, air bubbles can be well incorporated into the coating layer, and the thermal conductivity of the coating layer can be further reduced. When the content of the epoxy compound is below the upper limit, the time required for stirring can be minimized, so a coating layer can be formed with good workability.

[0071] [Photocurable compound] The above photocurable compound has a photocurable functional group. Preferably, the above photocurable compound has an ultraviolet-curable functional group.

[0072] Examples of the above UV-curable functional groups (photocurable functional groups) include ethylenically unsaturated bonding groups, epoxy groups, vinyl ether groups, glycidyl ether groups, and oxetanyl groups. Examples of the above ethylenically unsaturated bonding groups include (meth)acryloyl groups, vinyl groups, and allyl groups.

[0073] Examples of the above-mentioned photocurable compounds include (meth)acrylic compounds, vinyl compounds, and maleimide compounds. The above-mentioned photocurable compounds may be used individually or in combination of two or more.

[0074] The above photocurable compound may also be a photo- and thermosetting compound. The above photo- and thermosetting compound may have a (meth)acryloyl group and a cyclic ether group, or it may have a (meth)acryloyl group and an epoxy group.

[0075] Examples of photocurable compounds having the above-mentioned (meth)acryloyl group and epoxy group include glycidyl (meth)acrylate, allyl glycidyl ether, 4-hydroxybutyl (meth)acrylate glycidyl ether, and 3,4-epoxycyclohexylmethyl (meth)acrylate.

[0076] From the viewpoint of increasing the curing speed of the coating agent, the above photocurable compound is preferably glycidyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate glycidyl ether, and more preferably 4-hydroxybutyl (meth)acrylate glycidyl ether.

[0077] When the binder contains the photocurable compound, the content of the photocurable compound in 100% by weight of the coating agent is preferably 20% by weight or more, more preferably 40% by weight or more, even more preferably 50% by weight or more, preferably 99% by weight or less, more preferably 98% by weight or less, even more preferably 90% by weight or less, and particularly preferably 80% by weight or less. When the content of the photocurable compound is above the lower limit, air bubbles can be well incorporated into the coating layer, and the thermal conductivity of the coating layer can be further reduced. When the content of the photocurable compound is below the upper limit, the time required for stirring can be minimized, so a coating layer can be formed with good workability.

[0078] When the binder contains the photo- and thermosetting compounds, the content of the photo- and thermosetting compounds in 100% by weight of the coating agent is preferably 20% by weight or more, more preferably 40% by weight or more, even more preferably 50% by weight or more, preferably 99% by weight or less, more preferably 98% by weight or less, even more preferably 90% by weight or less, and particularly preferably 80% by weight or less. When the content of the photo- and thermosetting compounds is above the lower limit, air bubbles can be well incorporated into the coating layer, and the thermal conductivity of the coating layer can be further reduced. When the content of the photo- and thermosetting compounds is below the upper limit, the time required for stirring can be minimized, so a coating layer can be formed with good workability.

[0079] When the binder contains the thermosetting compound or the photocurable compound, the coating agent is preferably free of organic solvents or contains 30% by weight or less of organic solvents. When the binder contains the thermosetting compound or the photocurable compound, the content of the organic solvent in 100% by weight of the coating agent is preferably 30% by weight or less, more preferably 20% by weight or less, even more preferably 10% by weight or less, and particularly preferably 5% by weight or less. When the binder contains the thermosetting compound or the photocurable compound, it is most preferable that the coating agent is free of organic solvents.

[0080] <Foam stabilizer> The above coating agent contains a foam stabilizer. Because the above coating agent contains the foam stabilizer, it prevents the coarsening and uneven distribution of air bubbles in the coating agent, and allows the air bubbles to be well dispersed in the binder.

[0081] Examples of the foam stabilizers mentioned above include polyoxyalkylene foam stabilizers and silicone foam stabilizers. Examples of the polyoxyalkylene foam stabilizers include polyoxyalkylene alkyl ethers. Examples of the silicone foam stabilizers include organopolysiloxanes. One type of foam stabilizer may be used, or two or more types may be used in combination.

[0082] The foam stabilizer described above may be a solid at 25°C or a liquid at 25°C. From the viewpoint of further improving the heat insulation properties of the coating layer, it is preferable that the foam stabilizer be a liquid at 25°C.

[0083] From the viewpoint of further enhancing the thermal insulation properties of the coating layer, it is preferable that the foam stabilizer has thixotropic properties. From the viewpoint of further enhancing the thermal insulation properties of the coating layer, it is preferable that the foam stabilizer contains a foam stabilizer having thixotropic properties. From the viewpoint of further enhancing the thermal insulation properties of the coating layer, it is preferable that the foam stabilizer also acts as a thixotropic agent.

[0084] Examples of thixotropic foam stabilizers include amide foam stabilizers such as amides and polyamides; and polyether phosphate esters. The thixotropic foam stabilizers may be used individually or in combination of two or more types.

[0085] From the viewpoint of further improving the heat insulation properties of the coating layer, it is preferable that the foam stabilizer described above includes an amide foam stabilizer.

[0086] Commercially available foam stabilizers may be used as described above. Examples of commercially available foam stabilizers include "Disparon F-9040" manufactured by Kusumoto Kasei Co., Ltd.

[0087] In 100% by weight of the above coating agent, the content of the above foam stabilizer is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, even more preferably 1.0% by weight or more, preferably 10.0% by weight or less, more preferably 7.0% by weight or less, and even more preferably 5.0% by weight or less. When the content of the above foam stabilizer is above the lower limit and below the upper limit, bubbles can be dispersed more effectively in the above binder.

[0088] The amount of the foam stabilizer per 100 parts by weight of the binder is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, even more preferably 0.2 parts by weight or more, preferably 5.0 parts by weight or less, more preferably 3.0 parts by weight or less, and even more preferably 1.0 part by weight or less. When the amount of the foam stabilizer is above the lower limit and below the upper limit, bubbles can be dispersed more effectively in the binder.

[0089] <particle> The above coating agent may or may not contain particles. From the viewpoint of further improving the heat insulation properties of the resulting coating layer, it is preferable that the above coating agent contains particles.

[0090] Examples of the above-mentioned particles include hollow particles and solid particles. Only one type of particle may be used, or two or more types may be used in combination.

[0091] From the viewpoint of further improving the thermal insulation properties of the resulting coating layer, the particles are preferably hollow particles. Only one type of hollow particle may be used, or two or more types may be used in combination.

[0092] Examples of the above-mentioned hollow particles include balloon particles and porous hollow particles. A balloon particle is a particle having one void inside. A porous hollow particle is a particle having multiple voids inside. The multiple voids in the porous hollow particle may exist independently or some may be connected.

[0093] From the viewpoint of further improving the thermal insulation properties of the resulting coating layer, the hollow particles are preferably balloon particles or porous hollow particles. From the viewpoint of increasing the hollowness ratio of the particles and further improving the thermal insulation properties of the resulting coating layer, it is more preferable that the hollow particles include both balloon particles and porous hollow particles.

[0094] The hollowness ratio of the hollow particles is preferably 40 volume% or more, more preferably 45 volume% or more, preferably 99 volume% or less, more preferably 80 volume% or less, even more preferably 70 volume% or less, and particularly preferably 60 volume% or less. When the hollowness ratio of the hollow particles is above the lower limit and below the upper limit, the shape of the hollow particles is well maintained, and as a result, the thermal insulation properties of the resulting coating layer can be further enhanced.

[0095] The hollowness ratio of the above-mentioned hollow particles is calculated using the following formula.

[0096] Hollow fraction (volume %) of a hollow particle = (AB) / A × 100

[0097] A: Theoretical density of the material constituting the hollow particle (g / cm³) 3 ) B: Density of hollow particles (g / cm³) 3 )

[0098] The hollow particles described above may be resin hollow particles, inorganic hollow particles, or organic hollow particles with a glass shell. Examples of resin hollow particles include thermoplastic resin particles and thermosetting resin particles. Examples of inorganic hollow particles include glass particles, shirasu balloons, fly ash balloons, aerogel, and ceramic particles.

[0099] From the viewpoint of further improving the heat insulation properties of the coating layer, the hollow particles are preferably thermoplastic resin particles, and more preferably acrylic resin particles. The material constituting the hollow particles is preferably thermoplastic resin, and more preferably acrylic resin. The hollow particles preferably contain thermoplastic resin, and more preferably acrylic resin.

[0100] Examples of monomers constituting the above-mentioned thermoplastic resin include compounds having a styrene skeleton, compounds having a (meth)acryloyl group, vinyl acetate, vinyl ether compounds, vinyl ketone compounds, and olefin compounds. The above-mentioned thermoplastic resin may be a homopolymer using only one of the above-mentioned compounds (monomers), or it may be a copolymer using two or more of the above-mentioned compounds (monomers).

[0101] Examples of compounds having the styrene skeleton mentioned above include styrene, parachlorostyrene, and α-methylstyrene.

[0102] Examples of compounds having the (meth)acryloyl group include (meth)acrylic acid and (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, nitrile acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, and 2-ethylhexyl methacrylate.

[0103] Examples of the vinyl ether compounds mentioned above include vinyl methyl ether and vinyl isobutyl ether.

[0104] Examples of the vinyl ketone compounds mentioned above include vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone.

[0105] Examples of the olefin compounds mentioned above include ethylene, propylene, and butadiene.

[0106] Furthermore, the material constituting the hollow particles may be a mixture of a non-vinyl resin and the vinyl resin, or a graft polymer obtained by polymerizing a vinyl compound in the presence of the non-vinyl resin and the vinyl resin. Examples of the non-vinyl resin include epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, and modified rosin.

[0107] From the viewpoint of further improving the heat insulation properties of the coating layer, the hollowness ratio of the hollow particles is preferably 30% or more, more preferably 35% or more, and even more preferably 40% or more.

[0108] The hollow particles described above may be expandable or non-expandable hollow particles. Expandable hollow particles are particles whose volume (or internal pores) increases due to external stimuli such as heat.

[0109] Commercially available hollow particles may be used as described above. Examples of commercially available resin hollow particles include Advancel EM and Advancel HB (both manufactured by Sekisui Chemical Co., Ltd.), Expancel U and Expancel E (both manufactured by Nippon Ferrite Co., Ltd.), Matsumoto Microsphere F and Matsumoto Microsphere FE (both manufactured by Matsumoto Oil & Pharmaceutical Co., Ltd.). Examples of commercially available inorganic hollow particles include Silinax (manufactured by Nippon Steel Industries Co., Ltd.), E-Spheres (manufactured by Taiyo Cement Co., Ltd.), Hardlight (manufactured by Showa Chemical Co., Ltd.), Senolite, Marllight, and Glass Balloon (all manufactured by Tomoe Industries Co., Ltd.).

[0110] The specific gravity of the above particles is preferably 0.01 or higher, more preferably 0.10 or higher, preferably 1.00 or lower, more preferably 0.70 or lower, even more preferably 0.60 or lower, still more preferably 0.50 or lower, still more preferably 0.40 or lower, particularly preferably 0.30 or lower, and most preferably 0.20 or lower. When the specific gravity of the above particles is above the lower limit and below the upper limit, the uniform dispersion of the particles in the coating agent can be further improved, and as a result, the heat insulation properties of the resulting coating layer can be further improved.

[0111] The specific gravity of the above particles is equal to the density of water (1.0 g / cm³). 3 This refers to the density of particles relative to ).

[0112] The average particle diameter of the above particles is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, preferably 500 μm or less, more preferably 100 μm or less, and even more preferably 70 μm or less. When the average particle diameter of the above particles is above the lower limit and below the upper limit, the coating layer can be formed with good workability.

[0113] The average particle size of the above particles refers to the average value (D50) of the particle size measured by the laser diffraction scattering particle size distribution method for particles in a powder state.

[0114] The content of the above particles in 100% by weight of the above coating agent is preferably 10.0% by weight or less, more preferably 7.0% by weight or less, even more preferably 5.0% by weight or less, and particularly preferably 3.0% by weight or less. When the content of the above particles is below the above upper limit, the uniform dispersion of particles in the coating agent and the resulting coating layer is further enhanced, a coating layer of uniform thickness can be formed well, and as a result, the heat insulation properties of the resulting coating layer can be further enhanced. In addition, when the content of the above particles is below the above upper limit, the workability when manufacturing the coating agent is improved and manufacturing costs can be reduced. The lower limit of the content of the above particles is not particularly limited. The content of the above particles may be 0.1% by weight or more, 0.3% by weight or more, or 0.5% by weight or more.

[0115] The content of the hollow particles in 100% by weight of the above coating agent is preferably 10.0% by weight or less, more preferably 7.0% by weight or less, even more preferably 5.0% by weight or less, and particularly preferably 3.0% by weight or less. When the content of the hollow particles is below the above upper limit, the uniform dispersion of the hollow particles in the coating agent and the resulting coating layer is further enhanced, allowing for the formation of a coating layer of uniform thickness, and as a result, the heat insulation properties of the resulting coating layer can be further enhanced. Furthermore, when the content of the hollow particles is below the above upper limit, the workability when manufacturing the coating agent is improved, and manufacturing costs can be reduced. The lower limit of the content of the hollow particles is not particularly limited. The content of the hollow particles may be 0.1% by weight or more, 0.3% by weight or more, or 0.5% by weight or more.

[0116] The particle content per 100 parts by weight of the binder is preferably 10.0 parts by weight or less, more preferably 7.0 parts by weight or less, even more preferably 5.0 parts by weight or less, and particularly preferably 3.0 parts by weight or less. When the particle content is below the upper limit, the uniform dispersion of particles in the coating agent and the resulting coating layer is further enhanced, allowing for the formation of a coating layer of uniform thickness, and as a result, the thermal insulation properties of the resulting coating layer can be further improved. Furthermore, when the particle content is below the upper limit, the workability when manufacturing the coating agent is improved, and manufacturing costs can be reduced. The lower limit of the particle content is not particularly limited. The particle content may be 0.1 parts by weight or more, 0.3 parts by weight or more, or 0.5 parts by weight or more.

[0117] <Other ingredients> The above coating agent may contain other components besides the binder, foam stabilizer, and particles. Examples of these other components include photoinitiators, sensitizers, leveling agents, fluorescent agents, antistatic agents, and fillers. Only one of these other components may be used, or two or more may be used in combination.

[0118] (Electronic components and methods for manufacturing electronic components) The electronic component according to the present invention comprises a circuit board, an electronic element mounted on the circuit board, and a solder joint that electrically connects the circuit board and the electronic element, and further comprises a coating layer. In the electronic component according to the present invention, the coating layer coats the solder joint. In the electronic component according to the present invention, the material of the coating layer is the above-mentioned coating agent for electronic components.

[0119] Furthermore, the electronic component according to the present invention comprises a circuit board, an electronic element mounted on the circuit board, and a solder joint that electrically connects the circuit board and the electronic element, and further comprises a coating layer. In the electronic component according to the present invention, the coating layer coats the solder joint. In the electronic component according to the present invention, the volume occupied by air bubbles in 100% by volume of the coating layer is 10% by volume or more.

[0120] The electronic component according to the present invention has the above configuration, which enhances the heat insulation of the coating layer. As a result, it is possible to suppress the occurrence of connection failures between the soldered part and the circuit board due to partial remelting of the soldered part. In the electronic component according to the present invention, for example, even if injection molding is performed using the electronic component and resin, the soldered part of the electronic component is less likely to remelt, and connection failures (damage to the electronic component) between the soldered part and the circuit board can be suppressed. In the electronic component according to the present invention, it is possible to effectively suppress the occurrence of connection failures (damage to the electronic component) between the soldered part and the circuit board due to heat conduction from the resin used in injection molding (resin for sealing the electronic component).

[0121] The above-mentioned circuit board is not particularly limited. Conventional circuit boards can be used as the above-mentioned circuit board.

[0122] Examples of the above-mentioned electronic elements include semiconductor elements, resistor chips, capacitors, and external connection terminals.

[0123] The above-mentioned electronic component may have multiple electronic elements. If the above-mentioned electronic component has multiple electronic elements, the electronic elements may be of only one type or of two or more types.

[0124] The soldered portion described above is formed by solder. The solder is not particularly limited. Examples of solder include Sn-Pb alloys, Sn-Ag-Cu alloys, Sn-Zn-Bi alloys, and Sn-Zn-Al alloys. From the viewpoint of environmental protection, the solder in the soldered portion is preferably lead-free, and more preferably Sn-Ag-Cu alloys, Sn-Zn-Bi alloys, or Sn-Zn-Al alloys.

[0125] From the viewpoint of improving workability when electrically connecting a circuit board and an electronic element, the melting point of the solder joint is preferably 250°C or lower, more preferably 220°C or lower, even more preferably 200°C or lower, and particularly preferably 190°C or lower. The lower limit of the melting point of the solder joint is not particularly limited. The melting point of the solder joint may be 100°C or higher, or 120°C or higher.

[0126] From the viewpoint of miniaturizing electronic components by reducing the distance between electronic elements and increasing the mounting density of electronic elements, the thickness of the solder portion is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 500 μm or less. The lower limit of the thickness of the solder portion is not particularly limited. The thickness of the solder portion may be 10 μm or more, 50 μm or more, or 100 μm or more.

[0127] The volume occupied by bubbles in 100% by volume of the above coating layer (bubble volume ratio in the coating layer) is 10% by volume or more. Preferably, the bubble volume ratio in the above coating layer is 12% by volume or more, more preferably 15% by volume or more, even more preferably 18% by volume or more, preferably 40% by volume or less, more preferably 35% by volume or less, and even more preferably 30% by volume or less. If the bubble volume ratio in the above coating layer is above the lower limit, the heat insulation properties of the coating layer can be further enhanced, and damage to electronic components can be further suppressed. If the bubble volume ratio in the above coating layer is below the upper limit, the coating layer can be formed more uniformly.

[0128] In the electronic component according to the present invention, the volume fraction of bubbles in the coating layer can be measured, for example, by the following method. A coating layer is formed using the above coating agent. The above coating layer is cut to an arbitrary size (for example, 100 mm in length, 100 mm in width, and 0.3 mm in thickness) to prepare a test specimen. The thickness of the above coating layer may be the thickness of the coating layer in the electronic component. The test specimen is weighed in air (W1). Next, the test specimen is immersed in a working liquid at a constant temperature t (25°C). After the test specimen reaches a constant temperature t, the test specimen is weighed in the working liquid by a load exchange mechanism (W2). Water is used as the working liquid.

[0129]

number

[0130] ρ t : Density of the test specimen at temperature t (g / cm³) 3 ) W1: Weighing value of the test specimen in air (g) W2: Weighing value (g) of the test specimen in the working fluid. ρ s : Density of the working fluid at temperature t (g / cm³) 3 ) ρ air : Density of air (g / m³) 3 )

[0131] Next, the volume fraction of bubbles in the coating layer is calculated based on the following formula.

[0132] Bubble volume fraction (%) in the coating layer = 100 - (ρ t (ρ*100)

[0133] ρ t : Density of the test specimen at temperature t (g / cm³) 3 ) ρ: Density of the test specimen without air bubbles (g / cm³) 3 )

[0134] The density of the bubble-free test specimen used to determine ρ is ρ t The density of a test specimen containing air bubbles can be measured in the same manner as the density of a test specimen containing air bubbles used to determine the air bubble content. A test specimen without air bubbles can be prepared using a coating agent that does not contain air bubbles. The coating agent without air bubbles is prepared in the same way as the coating agent containing air bubbles, except that it does not contain air bubbles. The composition of the coating agent containing air bubbles and the coating agent without air bubbles are the same. To obtain the coating agent without air bubbles, the stirring conditions during the preparation of the coating agent can be adjusted.

[0135] The diameter of the bubbles in the coating layer is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, preferably 500 μm or less, more preferably 450 μm or less, and even more preferably 400 μm or less. If the diameter of the bubbles in the coating layer is above the lower limit, the heat insulation properties of the coating layer can be further enhanced, and damage to electronic components can be further suppressed. If the diameter of the bubbles in the coating layer is below the upper limit, the coating layer can be formed more uniformly.

[0136] If the bubble is closed and spherical, the bubble diameter is the diameter of the bubble. If the bubble is closed but has a shape other than spherical, the bubble diameter is the longest distance between two points on the outer circumference of the bubble, i.e., the maximum diameter of the bubble. Similarly, if the bubble is open, the bubble diameter is the longest distance between two points on the outer circumference of the bubble, i.e., the maximum diameter of the bubble. The bubble diameter represents the average value of the bubble diameters of at least 10 bubbles, and is preferably the average value of the bubble diameters of 10 arbitrarily selected bubbles.

[0137] The thermal conductivity of the coating layer is preferably 0.150 W / m·K or less, more preferably 0.145 W / m·K or less, even more preferably 0.140 W / m·K or less, and particularly preferably 0.135 W / m·K or less. When the thermal conductivity of the coating layer is below the above upper limit, the heat insulation properties of the coating layer can be further enhanced, and damage to electronic components can be further suppressed. The lower limit of the thermal conductivity of the coating layer is not particularly limited. The thermal conductivity of the coating layer may be 0.005 W / m·K or more, 0.010 W / m·K or more, or 0.015 W / m·K or more.

[0138] The thermal conductivity of the above-mentioned coating layer can be measured, for example, by the following method: The thermal conductivity in the thickness direction of the above-mentioned coating layer is measured at 23°C using a "Rapid Thermal Conductivity Meter QTM-500" manufactured by Kyoto Electronics Manufacturing Co., Ltd.

[0139] Figure 1 is a schematic cross-sectional view showing an electronic component using a coating agent for electronic components according to one embodiment of the present invention. Figure 1 also corresponds to a schematic cross-sectional view showing an electronic component according to one embodiment of the present invention.

[0140] The electronic component 1 shown in Figure 1 comprises a circuit board 2, an electronic element 5 mounted on the circuit board 2, and a solder joint 3 that electrically connects the circuit board 2 and the electronic element 5, and further comprises a coating layer 4. The coating layer 4 coats the solder joint 3.

[0141] In electronic component 1, the electronic element 5 is mounted on the circuit board 2. In electronic component 1, the circuit board 2 and the electronic element 5 are electrically connected by a solder joint 3. The solder joint 3 is located on the surface of the circuit board 2. The solder joint 3 is located on the surface of the circuit board 2 on the side facing the electronic element 5.

[0142] The coating layer 4 coats (covers) the solder portion 3. The coating layer 4 coats the solder portion 3 that is placed on the surface of the circuit board 2. In the electronic component 1, the coating layer 4 is placed over a wider area than the solder portion 3 on the surface of the solder portion 3 that is not in contact with the circuit board 2 and the electronic element 5. In the electronic component 1, the coating layer 4 is placed over the entire surface of the solder portion 3 that is not in contact with the circuit board 2 and the electronic element 5. In the electronic component 1, the coating layer 4 is placed so as to cover the solder portion 3. In the electronic component 1, the solder portion 3 is coated (covered) by the coating layer 4.

[0143] The coating layer 4 contains air bubbles (not shown). The volume percentage of air bubbles in the coating layer 4 is 10% by volume or more.

[0144] The coating layer may coat (cover) only a portion of the surface of the soldered portion, or it may coat (cover) the entire surface of the soldered portion. From the viewpoint of more effectively suppressing connection failures between the soldered portion and the circuit board, it is preferable that the coating layer coats (covers) the entire surface of the soldered portion. From the viewpoint of more effectively suppressing connection failures between the soldered portion and the circuit board, it is preferable that the coating layer is arranged to cover the soldered portion.

[0145] The above-mentioned coating layer may coat (cover) at least a portion of the circuit board, or it may not coat the circuit board at all. From the viewpoint of more effectively suppressing connection failures between the solder portion and the circuit board, it is preferable that the above-mentioned coating layer coats a portion of the area on the solder portion side (electronic element side) of the circuit board where the solder portion is not located.

[0146] The coating layer may coat (cover) at least a portion of the electronic element, or it may not coat the electronic element. From the viewpoint of more effectively suppressing connection failures between the solder portion and the circuit board, it is preferable that the coating layer coats a portion of the area on the solder portion side (circuit board side) of the electronic element where the solder portion is not located.

[0147] The method for manufacturing the above electronic component is not particularly limited. The method for manufacturing the above electronic component uses an electronic component body that includes a solder portion for electrically connecting the circuit board and the electronic element. The method for manufacturing the above electronic component preferably includes the following steps: (1) Using the electronic component body, place the above-mentioned coating agent on the surface of the solder portion so as to coat the solder portion. (2) Form a coating layer with the above-mentioned coating agent.

[0148] The above electronic component body may be obtained, or the above electronic component body may be manufactured. The manufacturing method of the above electronic component may include the following steps: (0) A step of manufacturing an electronic component body comprising a circuit board, an electronic element mounted on the circuit board, and a solder joint for electrically connecting the circuit board and the electronic element.

[0149] In step (1) above, methods for placing the coating agent on the surface of the soldered part include applying it with a dispenser and dipping. The thickness of the coating layer obtained by placing the coating agent on the surface of the soldered part is not particularly limited. The thickness of the coating layer may be 50 μm or more, 100 μm or more, 150 μm or more, 200 μm or more, 1000 μm or less, or 500 μm or less.

[0150] In step (2) above, it is preferable to form a coating layer by curing or drying the coating agent.

[0151] The method for curing the above-mentioned coating agent can be appropriately changed depending on the type of curable compound contained in the coating agent. Methods for curing the coating agent include irradiating the coating agent (coating layer) with ultraviolet light, heating the coating agent (coating layer), and allowing the coating agent to cure naturally after placement. The irradiation intensity when irradiating the coating agent with ultraviolet light and the heating temperature when heating the coating agent are appropriately set depending on the type of curable compound.

[0152] The method for drying the above-mentioned coating agent is not particularly limited. The method for drying the above-mentioned coating agent may be drying at room temperature, or it may be drying using a hot air device or the like.

[0153] From the viewpoint of ensuring good sealing of electronic components, the thickness of the coating layer is preferably 50 μm or more, more preferably 100 μm or more, even more preferably 150 μm or more, particularly preferably 200 μm or more, preferably 1000 μm or less, and more preferably 500 μm or less.

[0154] The above-mentioned electronic component may have an insulating layer on the surface of the soldered portion. The above-mentioned electronic component may also have an insulating layer between the soldered portion and the coating layer. In this case, the insulation reliability of the electronic component can be further improved.

[0155] The above-mentioned electronic components may be housed and integrated within a casing to protect them, and used as an electronic component module. In recent years, there has been a demand for miniaturization of electronic component modules, and instead of housing the electronic components within a casing, the electronic components themselves are encapsulated with resin or the like to form an integrated electronic component module. The above-mentioned electronic component module is manufactured by placing the electronic components in a mold and performing injection molding (in-mold molding). However, when conventional coating agents are used, the heat from the molten resin is transferred to the electronic components during injection molding, causing the solder joints to partially remelt, which can result in damage to the electronic components. In contrast, the present invention allows for the formation of a coating layer with uniform heat insulation properties using the coating agent, making it difficult for heat to be transferred to the solder joints and suppressing damage to the electronic components. In this invention, encapsulating electronic components with thermoplastic resin means integrating or protecting electronic components, sensors, external connection terminals, etc., with thermoplastic resin, and there may be parts of the substrate, sensors, cables, etc. that are not covered with thermoplastic resin.

[0156] The above-described electronic component module preferably comprises a circuit board, electronic elements mounted on the circuit board, solder joints for electrically connecting the circuit board and the electronic elements, a coating layer for coating the solder joints, and a covering portion for sealing the electronic components. In the above-described electronic component module, the material of the coating layer is preferably the above-described coating agent for electronic components.

[0157] The covering portion is preferably formed from a thermoplastic resin. The material of the covering portion that seals the electronic component preferably contains a thermoplastic resin. Examples of the thermoplastic resin include polyacetal resin, polyamide resin, polycarbonate resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, acrylic resin, and ABS resin. From the viewpoint of improving moldability and mechanical properties, the thermoplastic resin is preferably polybutylene terephthalate resin.

[0158] The above-mentioned electronic component module is preferably formed by injection molding the above-mentioned electronic component and the material of the covering portion.

[0159] The above-mentioned electronic component module can be manufactured by modularizing electronic components. The above-mentioned electronic component module is preferably an electronic control unit (ECU). The above-mentioned electronic control unit is preferably an electronic control unit for aircraft or automobiles, and more preferably an electronic control unit related to sensors.

[0160] The present invention will be specifically described below with reference to examples and comparative examples. The present invention is not limited to the following examples.

[0161] The following materials were prepared.

[0162] (binder) Photocurable compound (Sanyurec Co., Ltd. "MX-300L", viscosity at 25°C: 180 mPa·s)

[0163] The viscosity of the above binder at 25°C was measured using an E-type viscometer (TVE22L, manufactured by Toki Sangyo Co., Ltd.) under the conditions of 25°C and 5 rpm.

[0164] (Foam stabilizer) Amid foam stabilizer (Disparon F-9040, manufactured by Kusumoto Kasei Co., Ltd.)

[0165] (particle) Hollow particles (Sekisui Chemical Co., Ltd. "XX-41DH", Material: Polyacrylonitrile, Specific gravity: 0.4, Hollowness ratio: 50% by volume, Average particle size: 20 μm)

[0166] (Example 1) (1) Preparation of coating agents for electronic components A coating agent for electronic components (coating agent) was prepared by mixing 97% by weight of a binder ("MX-300L" manufactured by Sanyurec Co., Ltd.) and 3% by weight of a foam stabilizer ("Disparon F-9040" manufactured by Kusumoto Kasei Co., Ltd.), and stirring the mixture at 7000 rpm for 60 seconds using a stirrer ("Pencil Mixer" manufactured by AS ONE Corporation).

[0167] (2) Fabrication of electronic components The obtained coating agent was applied to the surface of the solder joint of an electronic component to form a coating layer with a thickness of 300 μm. The coating layer was then exposed to an irradiation intensity of 140 mW / cm². 2 The coating layer was cured by irradiating it with ultraviolet light for 5 minutes to form a coating layer, and then an electronic component was fabricated.

[0168] (Examples 2-5 and Comparative Example 1) Except for the composition of the coating agent and the stirring time during preparation of the coating agent, which are shown in Table 1 below, a coating agent for electronic components and an electronic component were obtained in the same manner as in Example 1.

[0169] (evaluation) (1) Bubble volume fraction in the coating layer The obtained coating agent was applied to a glass substrate to form a coating layer with a thickness of 300 μm (0.3 mm). The coating layer was then exposed to an irradiation intensity of 140 mW / cm². 2The coating layer was cured by irradiating it with ultraviolet light for 5 minutes to form a coating layer. The above coating layer was cut to a size of 100 mm in length, 100 mm in width, and 300 μm (0.3 mm) in thickness to prepare test specimens. For the obtained test specimens, the volume occupied by air bubbles in 100% volume of the coating layer formed by the coating agent (air bubble volume fraction in the coating layer) was measured using the method described above.

[0170] (2) Thermal insulation properties of the coating layer The obtained coating agent was applied to a glass substrate to form a coating layer. The coating layer was then exposed to an irradiation intensity of 140 mW / cm². 2 The coating layer was cured by irradiating it with ultraviolet light for 5 minutes, forming a coating layer with a thickness of 300 μm (0.3 mm). The thermal conductivity in the thickness direction of the obtained coating layer was measured at 23°C using a "Rapid Thermal Conductivity Meter QTM-500" manufactured by Kyoto Electronics Manufacturing Co., Ltd. The thermal insulation performance of the coating layer was judged according to the following criteria.

[0171] [Criteria for judging the thermal insulation properties of coating layers] ○: Thermal conductivity of the coating layer is 0.150 W / m·K or less. ×: The thermal conductivity of the coating layer exceeds 0.150 W / m·K.

[0172] The composition and results of the coating agent for electronic components are shown in Table 1 below.

[0173] [Table 1]

[0174] (Other test examples) A binder ("MX-300L" manufactured by Sunyurec Co., Ltd.), a foam stabilizer ("Disparon F-9040" manufactured by Kusumoto Kasei Co., Ltd.), and particles ("XX-41DH" manufactured by Sekisui Kasei Kogyo Co., Ltd.) were mixed and stirred using a stirrer ("Pencil Mixer" manufactured by AS ONE Co., Ltd.). Two coating agents for electronic components were prepared: one with a bubble volume ratio of 12 vol% in the coating layer described in (1) above (coating agent A), and another with a bubble volume ratio of 20 vol% in the coating layer described in (1) above (coating agent B). Both coating agents A and B showed excellent results in terms of the thermal insulation properties of the coating layer described in (2) above. However, coating agents A and B required the effort of adding particles and incurred manufacturing costs. [Explanation of Symbols]

[0175] 1…Electronic components 2…Circuit board 3... Soldering section 4…Coating layer 5…Electronic elements

Claims

1. It is a coating agent used for electronic components. It contains a binder and a foam stabilizer. The binder comprises a thermoplastic resin, a thermosetting compound, or a photocurable compound. A coating agent for electronic components, wherein the volume of air bubbles in a 100% volume of the coating layer formed by the coating agent is 10% or more by volume.

2. The coating agent for electronic components according to claim 1, wherein the content of the foam stabilizer is 0.5% by weight or more and 5.0% by weight or less in 100% by weight of the coating agent.

3. A coating agent for electronic components according to claim 1 or 2, comprising particles.

4. The coating agent for electronic components according to claim 3, wherein the particles are hollow particles.

5. The coating agent for electronic components according to claim 3, wherein the specific gravity of the particles is 0.60 or less.

6. The coating agent for electronic components according to claim 3, wherein the content of the particles in 100% by weight of the coating agent is 3.0% by weight or less.

7. The coating agent for electronic components according to claim 1 or 2, wherein the binder comprises a photocurable compound.

8. A coating agent for an electronic component according to claim 1 or 2, used to form a coating layer for coating the solder portion in an electronic component comprising a circuit board, an electronic element mounted on the circuit board, and a solder portion electrically connecting the circuit board and the electronic element.

9. An electronic component comprising a circuit board, electronic elements mounted on the circuit board, and solder joints that electrically connect the circuit board and the electronic elements, With an additional coating layer, The coating layer coats the solder portion. An electronic component wherein the material of the coating layer is the coating agent for electronic components described in claim 1 or 2.

10. An electronic component comprising a circuit board, electronic elements mounted on the circuit board, and solder joints that electrically connect the circuit board and the electronic elements, With an additional coating layer, The coating layer coats the solder portion. An electronic component in which the volume occupied by air bubbles in the 100% volume of the coating layer is 10% or more by volume.

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