Coating agent and method for manufacturing electronic component module

Abstract

Provided is a coating agent with which it is possible to form a coating film having high heat insulation properties. The coating agent according to the present invention is used in an electronic component module in which an electronic component is mounted on a circuit board via a conductive adhesive section that is coated with a coating film, and the coating agent contains: a thermoplastic resin; a solvent that dissolves the thermoplastic resin; and hollow particles, the content of the thermoplastic resin being 1.0-22.0% by weight (inclusive) with respect to 100% by weight of the total content of the thermoplastic resin and the solvent, and the content of the hollow particles being 15.0-50.0 parts by weight (inclusive) with respect to 100 parts by weight of the total content of the thermoplastic resin and the solvent.

Description

Technical Field

[0001] The present invention relates to a coating agent for an electronic component module and a method for producing an electronic component module using the coating agent. Background Art

[0002] Various electronic component modules are used in automobiles, personal computers, mobile phones, etc. As an example of an electronic component module, a vehicle-mounted control unit (ECU: Electronic Control Unit) mounted on an automobile is known. The vehicle-mounted control unit usually includes a mounting body on which electronic components such as semiconductor components are mounted on a circuit substrate, and a housing for accommodating the mounting body. For example, in a state where the terminals of the electronic component are welded to the wiring circuit pattern of the circuit substrate, the electronic component is fixed to the circuit substrate. The housing generally includes a base for fixing the circuit substrate and a cover assembled to the base in a manner covering the circuit substrate as described in Patent Document 1.

[0003] Patent Document 2 discloses an electronic component module obtained by placing a mounted body in which electronic components are mounted on a circuit board in an injection molding die, and sealing the electronic components on the circuit board with a thermoplastic resin.

[0004] In recent years, electronic component modules such as the above-mentioned vehicle-mounted control devices have been required to be miniaturized due to space constraints. Accordingly, miniaturization of electronic components is required.

[0005] However, it is known that in order to cope with environmental problems, lead-free solders are often used in recent years. On the other hand, lead-free solders grow whiskers over time. In the automotive field, etc., with the miniaturization of electronic components, electronic circuits also tend to be miniaturized. There is a problem that adjacent electronic components or solders are short-circuited due to the growing whiskers in the circuit substrate using lead-free solder. In response to such problems, it is proposed in Patent Document 3 to coat the solder portion with hollow particles.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: WO2017 / 038343A1

[0009] Patent Document 2: Japanese Patent Application Publication No. 2012-151296

[0010] Patent Document 3: Japanese Patent Application Publication No. 2013-131559 Summary of the invention

[0011] Technical problem solved by the invention

[0012] As described in Patent Document 3, when hollow particles alone are used, the heat insulating properties of the electronic component module may not be sufficiently improved.

[0013] An object of the present invention is to provide a coating agent capable of forming a film having high heat-insulating properties. Another object of the present invention is to provide a method for producing an electronic component module having a film having high heat-insulating properties.

[0014] Technical means of solving problems

[0015] The present inventors considered that in an electronic component module in which an electronic component is mounted on a circuit board via a conductive adhesive portion, the conductive adhesive portion is covered with a film. The present inventors studied a coating agent for forming the film and found a coating agent composition that can improve the heat insulation of the obtained film.

[0016] In this specification, the following coating agent and method for producing an electronic component module are disclosed.

[0017] Item 1. A coating agent for forming a film in an electronic component module in which an electronic component is mounted on a circuit board via a conductive adhesive portion and the conductive adhesive portion is covered with a film, wherein:

[0018] The coating agent includes: a thermoplastic resin; a solvent that dissolves the thermoplastic resin; and hollow particles, wherein the content of the thermoplastic resin is 1.0% by weight or more and 22.0% by weight or less based on 100% by weight of the total content of the thermoplastic resin and the solvent, and the content of the hollow particles is 15.0 parts by weight or more and 50.0 parts by weight or less based on 100 parts by weight of the total content of the thermoplastic resin and the solvent.

[0019] Item 2. The coating agent according to Item 1, wherein

[0020] The boiling point of the solvent is 130° C. or lower.

[0021] Item 3. The coating agent according to Item 1 or 2, wherein

[0022] The viscosity of the composition containing the thermoplastic resin and the solvent contained in the coating agent at a weight ratio in the coating agent at 25° C. is 1 mPa·s or more and 350 mPa·s or less.

[0023] Item 4. The coating agent according to any one of Items 1 to 3, wherein

[0024] The hollow particles have a hollow ratio of 40% by volume or more and 99% by volume or less.

[0025] Item 5. The coating agent according to any one of Items 1 to 4, wherein

[0026] The specific gravity of the hollow particles is 5.0 or less.

[0027] Item 6. The coating agent according to any one of Items 1 to 5, wherein

[0028] The material of the hollow particles includes poly(meth)acrylonitrile or (meth)acrylic resin.

[0029] Item 7. A coating agent according to any one of Items 1 to 6, which is used to form the film in an electronic component module in which the electronic component is mounted on the circuit substrate via the conductive adhesive portion, the conductive adhesive portion is covered by the film, and the electronic component on the circuit substrate is sealed by a thermoplastic resin.

[0030] Item 8. A method for manufacturing an electronic component module, comprising:

[0031] A step of forming a coating, in which, in a mounted body in which an electronic component is mounted on a circuit board via a conductive adhesive portion, the conductive adhesive portion is coated with the coating agent according to any one of items 1 to 6 to form a coating covering the conductive adhesive portion.

[0032] Item 9. The method for manufacturing an electronic component module according to Item 8, further comprising:

[0033] The step of mounting the electronic component on the circuit board via the conductive adhesive portion.

[0034] Item 10. The method for manufacturing an electronic component module according to Item 8 or 9, further comprising:

[0035] The sealing step is to seal the electronic components on the circuit board with a thermoplastic resin.

[0036] Item 11. The method for manufacturing an electronic component module according to Item 10, wherein:

[0037] The electronic components on the circuit board are sealed with the thermoplastic resin by injection molding in a metal mold.

[0038] Effects of the Invention

[0039] The coating agent of the present invention is used to form the film in an electronic component module in which an electronic component is mounted on a circuit substrate via a conductive adhesive portion and the conductive adhesive portion is covered by a film. The coating agent of the present invention comprises a thermoplastic resin, a solvent for dissolving the thermoplastic resin, and hollow particles. In the coating agent of the present invention, the content of the thermoplastic resin is 1.0% by weight or more and 22.0% by weight or less in the total content of the thermoplastic resin and the solvent of 100 parts by weight, and the content of the hollow particles is 15.0 parts by weight or more and 50.0 parts by weight or less relative to the total content of the thermoplastic resin and the solvent of 100 parts by weight. In the coating agent of the present invention, since it has the above-mentioned structure, a film with high heat insulation can be formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] [ Figure 1 ] Figure 1 This is a cross-sectional view schematically showing an electronic component module using a coating agent according to one embodiment of the present invention. DETAILED DESCRIPTION

[0041] Hereinafter, the present invention is described in detail.

[0042] (Coating agent)

[0043] The coating agent of the present invention is used to form the film in an electronic component module in which an electronic component is mounted on a circuit substrate via a conductive adhesive portion and the conductive adhesive portion is covered by a film. (The purpose of the coating agent is to form the film in an electronic component module in which an electronic component is mounted on a circuit substrate via a conductive adhesive portion and the conductive adhesive portion is covered by a film.) The coating agent of the present invention comprises a thermoplastic resin, a solvent that dissolves the thermoplastic resin, and hollow particles. In the coating agent of the present invention, the content of the thermoplastic resin in 100 weight % of the total content of the thermoplastic resin and the solvent is 1.0 weight % or more and 22.0 weight % or less, and the content of the hollow particles is 15.0 weight % or more and 50.0 weight % or less relative to 100 weight parts of the total content of the thermoplastic resin and the solvent.

[0044] In the coating agent of the present invention, since it has the above-mentioned structure, it is possible to form a film with high thermal insulation. In the case of the coating agent of the present invention, the thermal insulation of the entire film can be made uniform. In the case of the coating agent of the present invention, when preparing an electronic component module, the remelting of the conductive adhesive portion and the thermal degradation of the circuit substrate (stress breakage caused by thermal expansion of the resin, etc.) can be suppressed. In particular, in the case of a process of sealing the electronic components on the circuit substrate with a thermoplastic resin by injection molding in a metal mold, the remelting of the conductive adhesive portion and the thermal degradation of the circuit substrate caused by the heat during the injection molding can be suppressed.

[0045] However, in order to improve the thermal insulation, it is considered to increase the content of hollow particles. The present inventors have found that when the content of hollow particles in the coating agent is simply increased, the viscosity of the coating agent becomes higher and the dispersibility of the hollow particles in the coating agent becomes lower. The present inventors have conducted in-depth research and found that by making the content of the thermoplastic resin in the total content of 100 weight % of the thermoplastic resin and the solvent, and the content of the hollow particles relative to the total content of 100 parts by weight of the thermoplastic resin and the solvent within the range, the dispersibility of the hollow particles in the coating agent can be greatly improved. By using the coating agent of the present invention, the thermal insulation of the film can be further improved, and the thermal insulation of the film as a whole can be made more uniform. Controlling the content of the thermoplastic resin and the content of the hollow particles, respectively, within the range is very helpful to greatly improve the thermal insulation of the film, and to make the thermal insulation of the film as a whole very uniform.

[0046] Hereinafter, the components used in the coating agent of the present invention will be described. It should be noted that in the following description, "(meth)acrylic" refers to one or both of "acrylic" and "methacrylic". "(Meth)acryloyl" refers to one or both of "acryloyl" and "methacryloyl".

[0047] [Thermoplastic resin]

[0048] The coating agent contains a thermoplastic resin (thermoplastic resin for coating). As the thermoplastic resin, a conventionally known thermoplastic resin can be used. In the coating agent, the thermoplastic resin is contained in a state of being dissolved in the solvent. In the coating agent, the thermoplastic resin is not contained in a state of particles.

[0049] Examples of the thermoplastic resin include synthetic resins and aqueous emulsion resins. The thermoplastic resin may be used alone or in combination of two or more.

[0050] Examples of the synthetic resin (thermoplastic resin) include polyolefin resins, phenolic resins, alkyd resins, aminoalkyd resins, urea resins, silicone resins, melamine urea, epoxy resins, polyurethane resins, vinyl acetate resins, (meth)acrylic resins, rubber resins, vinyl chloride resins, and fluororesins.

[0051] From the viewpoint of further improving the adhesiveness of the film, the thermoplastic resin preferably contains a polyolefin resin, and more preferably contains a polyolefin elastomer.

[0052] Examples of the polyolefin elastomer include copolymers of propylene and α-olefin; α-olefin polymers; ethylene-propylene rubbers such as ethylene-propylene rubber (EPM) and ethylene-propylene-diene rubber (EPDM); and chlorosulfonated polyethylene (CSM).

[0053] Examples of the aqueous emulsion resin (thermoplastic resin) include silicone (meth)acrylic emulsion resins, urethane emulsion resins, and (meth)acrylic emulsion resins.

[0054] In 100 wt % of the coating agent, the content of the thermoplastic resin is preferably 0.7 wt % or more, more preferably 5.0 wt % or more, further preferably 10.0 wt % or more, and preferably less than 19.5 wt %, more preferably less than 19.0 wt %, further preferably less than 18.0 wt %, and particularly preferably less than 17.0 wt %. When the content of the thermoplastic resin is greater than the lower limit and less than the upper limit (or less than the upper limit), the thermal insulation of the film can be further improved, and the thermal insulation of the entire film can be made more uniform.

[0055] In the total content of the thermoplastic resin and the solvent of 100 weight %, the content of the thermoplastic resin is 1.0 weight % or more and 22.0 weight % or less. When the content of the thermoplastic resin is 1.0 weight % or more and 22.0 weight % or less, the thermal insulation of the film can be improved and the thermal insulation of the entire film can be made uniform. In the total content of the thermoplastic resin and the solvent of 100 weight %, the content of the thermoplastic resin is preferably 2.0 weight % or more, more preferably 6.0 weight % or more, and further preferably 11.0 weight % or more. In the total content of the thermoplastic resin and the solvent of 100 weight %, the content of the thermoplastic resin is preferably 20.0 weight % or less, more preferably less than 20.0 weight %, further preferably 19.0 weight % or less, and particularly preferably 18.0 weight % or less. When the content of the thermoplastic resin is not less than the lower limit and not more than the upper limit (or less than the upper limit), the heat insulating property of the film can be further improved, and the heat insulating property of the entire film can be made more uniform.

[0056] [Solvent]

[0057] The coating agent contains a solvent. The solvent is a solvent that dissolves the thermoplastic resin. The solvent is a solvent that dissolves the thermoplastic resin. The solvent can preferably dissolve the thermoplastic resin at 25° C. The solvent functions as a dispersion medium for the hollow particles. The solvent can be appropriately selected and used in consideration of the solubility and volatilization rate of the thermoplastic resin, the dispersibility of the hollow particles, the compatibility with other fillers, and the compatibility with a dispersant, etc.

[0058] Examples of the solvent include water and organic solvents. The solvent may be used alone or in combination of two or more.

[0059] Examples of the organic solvent include ketone solvents, alcohol solvents, and aromatic solvents. Specifically, examples of the organic solvent include acetone, methyl ethyl ketone, alkyl cyclohexanes, cyclohexene, ethylene glycol, propylene glycol, methanol, ethanol, isopropanol, butanol, benzene, toluene, xylene, ethyl acetate, and butyl acetate.

[0060] From the viewpoint of further improving the heat insulating property of the film, the solvent preferably contains the alkylcyclohexane. From the viewpoint of further improving the heat insulating property of the film, the alkyl group in the alkylcyclohexane preferably has 1 to 5 carbon atoms.

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

[0062] From the viewpoint of further improving the heat-insulating properties of the film, the solvent preferably contains toluene or the alkylcyclohexane, and more preferably contains toluene or methylcyclohexane.

[0063] From the viewpoint of further improving the heat insulation of the film, the boiling point of the solvent is preferably below 150°C, more preferably below 140°C, and further preferably below 130°C. When the boiling point of the solvent is below the upper limit, it is possible to suppress adverse effects on electronic components (capacitors, etc.) mounted on the circuit board, and to allow the coating agent to dry quickly to form a film. The boiling point of the solvent may be above 50°C, above 60°C, above 70°C, above 80°C, above 100°C, or above 100°C. When the boiling point of the solvent is above the lower limit (or exceeds the lower limit), it is possible to suppress undesirable volatilization of the solvent and improve the operability of the coating agent.

[0064] [Hollow particles]

[0065] The coating agent contains hollow particles. The hollow particles impart heat insulation properties to the film. The hollow particles may be single-hole hollow particles or porous hollow particles. Single-hole hollow particles refer to particles having one empty hole inside the particle. Porous hollow particles refer to particles having multiple empty holes inside the particle. The multiple empty holes in the porous hollow particles may exist independently or may be connected. The solvent preferably cannot dissolve the hollow particles. In the coating agent, the hollow particles are contained in the form of particles. The hollow particles are preferably not dissolved in the solvent but contained in the coating agent.

[0066] Examples of the hollow particles include organic hollow particles and inorganic hollow particles. The hollow particles may be used alone or in combination of two or more.

[0067] As the organic hollow particles, thermoplastic resin particles, thermosetting resin particles, organic hollow particles with glass as shells (resin hollow particles), etc. can be cited. It should be noted that, when the hollow particles are the thermoplastic resin particles, the thermoplastic resin contained in the coating agent is different from the thermoplastic resin particles. When the hollow particles are the thermoplastic resin particles, the solvent is preferably a solvent that does not dissolve the hollow particles as the thermoplastic resin particles. The solvent is preferably a solvent that does not dissolve the hollow particles as the thermoplastic resin particles at 25°C.

[0068] Examples of the inorganic hollow particles include glass particles and ceramic particles.

[0069] From the viewpoint of improving mechanical properties, the hollow particles preferably include thermoplastic resin particles. As materials (thermoplastic resins) of the thermoplastic resin particles, there can be cited: monomers having a styrene skeleton (styrene, p-chlorostyrene, α-methylstyrene, etc.); monomers having a (meth)acryloyl group ((meth)acrylic acid and (meth)acrylate (methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, lauryl (meth)acrylate, (meth)acrylonitrile, and 2-ethylhexyl (meth)acrylate, etc.); vinyl acetate; vinyl ethers (vinyl methyl ether and vinyl isobutyl ether, etc.); vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone, etc.); homopolymers such as olefins (ethylene, propylene, and butadiene, etc.); and copolymers formed by combining two or more of these monomers, etc.

[0070] In addition, as materials for the hollow particles, there can be cited non-vinyl resins (epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins and modified rosin, etc.); mixtures of non-vinyl resins and vinyl resins; polymers obtained by polymerizing vinyl monomers (grafted polymers, etc.), etc.

[0071] From the viewpoint of further improving the heat insulating properties of the film, the material of the hollow particles preferably includes poly(meth)acrylonitrile or a (meth)acrylic resin.

[0072] The hollow particles may be expandable or non-expandable. It should be noted that expandable hollow particles are particles whose volume (or internal pores) increases due to external stimulation such as heat.

[0073] As the hollow particles, commercially available products can be used.

[0074] Commercially available products of the hollow particles include ADVANCELL EM, ADVANCELL HB (all manufactured by Sekisui Chemical Co., Ltd.); EXPANCEL WU, EXPANCEL DU, EXPANCEL WE and EXPANCEL DE (all manufactured by Nippon FILLITE Co., Ltd.); MATSUMOTO MICROSPHERE F, MATSUMOTO MICROSPHERE FE (all manufactured by Matsumoto Oil & Fats Pharmaceutical Co., Ltd.); TECHPOLYMER MBP (all manufactured by Sekisui Chemicals Co., Ltd.) and other resin hollow particles. In addition, commercially available products of the hollow particles include SILINAX (manufactured by Nippon Steel Industries Co., Ltd.); E-SPHERES (manufactured by Taiyo Cement Co., Ltd.); HARDLITE (manufactured by Showa Chemical Co., Ltd.); CENOLITE, MAARLITE, GLASS BALLOON (all manufactured by Bass Industries Co., Ltd.); GLASS BUBBLES (manufactured by 3M Co., Ltd.) and other inorganic hollow particles.

[0075] The hollow ratio of the hollow particles is preferably 40% by volume or more, more preferably 45% by volume or more, preferably 99% by volume or less, more preferably 95% by volume or less, further preferably 80% by volume or less, particularly preferably 70% by volume or less, and most preferably 60% by volume or less. When the hollow ratio is above the lower limit and below the upper limit, the heat insulation of the film can be further improved, and the heat insulation of the film as a whole can be made more uniform. In particular, after the solvent evaporates, the shape of the hollow particles can be well maintained.

[0076] The hollowness of the hollow particles can be measured by the following method.

[0077] When the theoretical density of the material constituting the hollow particles is set to (A) with respect to the measured value (B) of the density of the hollow particles, the hollowness (C) can be calculated by the following formula.

[0078] C(%)=(AB) / A×100

[0079] In the film, the hollow particles are preferably in a state of being uniformly dispersed in the thermoplastic resin. The specific gravity of the hollow particles is preferably less than 5.0, more preferably less than 3.0, further preferably less than 2.0, and particularly preferably less than 1.5. When the specific gravity is below the upper limit, the hollow particles in the film are more uniformly dispersed in the thermoplastic resin, which can make the thermal insulation of the film as a whole more uniform. The lower limit of the specific gravity of the hollow particles is not particularly limited. The specific gravity of the hollow particles can be greater than 0.01, greater than 0.1, or greater than 1.0.

[0080] The specific gravity of the hollow particles is the density of water (1.0 g / cm 3 ) of the hollow particles (measured value (B)).

[0081] The average particle size of the hollow particles is preferably 1 μm or more, more preferably 5 μm or more, further preferably 10 μm or more, and preferably 500 μm or less, more preferably 100 μm or less, and further preferably 70 μm or less. When the average particle size is above the lower limit and below the upper limit, the thermal insulation of the film can be further improved, and the thermal insulation of the film as a whole can be made more uniform. In addition, when the average particle size is above the lower limit and below the upper limit, the occurrence of slip can be suppressed.

[0082] The average particle size of the hollow particles refers to an average value (D50) of the particle sizes of the hollow particles in a powder state measured by a laser diffraction scattering particle size distribution measurement method, and means a number average particle size.

[0083] Relative to 100 parts by weight of the total content of the thermoplastic resin and the solvent, the content of the hollow particles is 15.0 parts by weight or more and 50.0 parts by weight or less. When the content of the hollow particles is 15.0 parts by weight or more and 50.0 parts by weight or less relative to 100 parts by weight of the total content of the thermoplastic resin and the solvent, the thermal insulation of the film can be improved, and the thermal insulation of the film as a whole can be made uniform. Relative to 100 parts by weight of the total content of the thermoplastic resin and the solvent, the content of the hollow particles is preferably 17.5 parts by weight or more, more preferably 20.0 parts by weight or more, and preferably 45.0 parts by weight or less, more preferably 40.0 parts by weight or less, further preferably 35.0 parts by weight or less, and particularly preferably 30.0 parts by weight or less. When the content of the hollow particles is above the lower limit and below the upper limit, the thermal insulation of the film can be further improved, and the thermal insulation of the film as a whole can be made more uniform.

[0084] [Other details of the coating agent]

[0085] With regard to the viscosity of the composition containing the thermoplastic resin and the solvent contained in the coating agent at a weight ratio in the coating agent at 25°C, it is preferably 1 mPa·s or more, and preferably 350 mPa·s or less, more preferably 250 mPa·s or less, and further preferably 150 mPa·s or less. When the viscosity of the composition is above the lower limit, it is easy to moderately thicken the thickness of the film. When the viscosity of the composition is above the lower limit and below the upper limit, the heat insulation can be further improved, the viscosity change of the coating agent containing hollow particles can be suppressed, and the coating property of the coating agent can be improved. In particular, when the viscosity of the composition at 25°C is below 250 mPa·s, the heat insulation can be further improved, and when the viscosity of the composition at 25°C is below 150 mPa·s, the heat insulation can be greatly improved.

[0086] The composition for measuring the viscosity only contains the thermoplastic resin and the solvent contained in the coating agent, and contains the thermoplastic resin and the solvent in a weight ratio in the coating agent. The composition for measuring the viscosity does not contain the hollow particles. The composition for measuring the viscosity is, for example, a solution in which the thermoplastic resin is dissolved in the solvent. In the case where the coating agent contains 15% by weight of the thermoplastic resin, 60% by weight of the solvent, and 25% by weight of the hollow particles in 100% by weight of the coating agent, the composition for measuring the viscosity contains 20% by weight of the thermoplastic resin and 80% by weight of the solvent in 100% by weight of the composition.

[0087] As described above, the coating agent of the present invention is used to form the coating film in an electronic component module in which an electronic component is mounted on a circuit board via a conductive adhesive portion and the conductive adhesive portion is covered with the coating film. As described above, the coating agent of the present invention can form a coating film having high heat insulation properties.

[0088] The coating agent of the present invention is preferably a coating agent used to form the coating in an electronic component module in which the electronic component is mounted on the circuit substrate via the conductive adhesive portion, the conductive adhesive portion is covered by the coating, and the electronic component on the circuit substrate is sealed by a thermoplastic resin. (The use of the coating agent for forming the coating in an electronic component module in which the electronic component is mounted on the circuit substrate via the conductive adhesive portion, the conductive adhesive portion is covered by the coating, and the electronic component on the circuit substrate is sealed by a thermoplastic resin.) By using the coating agent of the present invention, even if the electronic component is sealed with a thermoplastic resin, remelting of the conductive adhesive portion caused by the heat during sealing and thermal degradation of the circuit substrate can be suppressed.

[0089] (Electronic component module and method of manufacturing the same)

[0090] Figure 1 This is a cross-sectional view schematically showing an electronic component module using a coating agent according to one embodiment of the present invention.

[0091] Figure 1 The electronic component module 1 shown includes a circuit board 2 , a conductive adhesive portion 3 , a film 4 , an electronic component 5 , and a thermoplastic resin portion 6 .

[0092] In the electronic component module 1, the electronic component 5 is mounted on the circuit substrate 2 via the conductive adhesive portion 3. The circuit substrate 2 and the electronic component 5 are electrically connected via the conductive adhesive portion 3. The film 4 covers the conductive adhesive portion 3. The film 4 is also disposed on a portion of the surface of the circuit substrate 2. The electronic component 5 on the circuit substrate 2 is sealed by the thermoplastic resin portion 6. In addition, the conductive adhesive portion 3 on the circuit substrate 2 is sealed by the thermoplastic resin portion 6 via the film 4. The film 4 on the circuit substrate 2 is sealed by the thermoplastic resin portion 6.

[0093] The electronic component module comprises: a mounting body, wherein the electronic component is mounted on a circuit substrate via a conductive adhesive portion; the conductive adhesive portion; and a film covering the conductive adhesive portion. The electronic component module preferably comprises a thermoplastic resin portion (sealing portion) for sealing the electronic component on the circuit substrate. The film is formed by the coating agent. The conductive adhesive portion is formed by a conductive adhesive component. The thermoplastic resin portion is formed by a thermoplastic resin (sealing thermoplastic resin).

[0094] In the electronic component module, the film may cover only a part of the surface of the conductive adhesive portion, or may cover the entire surface of the conductive adhesive portion. In the electronic component module, the film is preferably configured in a manner to cover the conductive adhesive portion. In the electronic component module, the film may cover only a part of the surface of the circuit substrate, or may cover the entire surface of the circuit substrate. The conductive adhesive portion on the circuit substrate is preferably sealed with the thermoplastic resin portion via the film. The film on the circuit substrate is preferably sealed with the thermoplastic resin portion.

[0095] Examples of the electronic components include semiconductor elements, resistor chips, capacitors, and terminals for connecting to the outside.

[0096] As the conductive adhesive component, resin materials and solders containing conductive fillers can be cited. The conductive adhesive component is preferably solder. Therefore, the conductive adhesive portion formed by the conductive adhesive component is preferably a solder portion. The solder contains tin (Sn). As solder, Sn-Pb alloys, Sn-Ag-Cu alloys, Sn-Zn-Bi alloys, and Sn-Zn-Al alloys can be cited. From the perspective of environmental regulations, the solder is preferably a lead-free solder (lead-free solder), more preferably a Sn-Ag-Cu alloy, a Sn-Zn-Bi alloy, or a Sn-Zn-Al alloy.

[0097] Examples of the resin in the resin material containing the conductive filler include thermosetting resins such as epoxy resins and phenolic resins, and thermoplastic resins (thermoplastic resins for conductive adhesive portions) such as polyester resins, polyolefin resins, polyurethane resins, and polycarbonate resins. Examples of the conductive filler in the resin material containing the conductive filler include gold, silver, copper, nickel, and aluminum.

[0098] From the viewpoint of improving the workability when electrically connecting the circuit board and the electronic component, the melting point of the conductive adhesive component is preferably 250° C. or less, more preferably 220° C. or less, further preferably 200° C. or less, and particularly preferably 190° C. or less. It should be noted that when a thermosetting resin or the like is used as the resin in the resin material containing the conductive filler, if the melting point of the thermosetting resin cannot be measured, the heat-resistant temperature of the thermosetting resin is used as the melting point of the conductive adhesive component.

[0099] The thermoplastic resin used as the material of the thermoplastic resin portion is preferably a thermoplastic resin that can be injection molded. 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.

[0100] In conventional electronic component modules, when polybutylene terephthalate or the like is used as the material of the thermoplastic resin portion, the temperature during injection molding is generally about 230°C to 270°C, so the conductive adhesive portion may remelt due to the heat during injection molding. In the present invention, by pre-forming a film covering the conductive adhesive portion, heat propagation to the conductive adhesive portion and the electronic component can be reduced, thereby suppressing damage to the electronic component caused by remelting of the conductive adhesive portion and thermal expansion of the resin.

[0101] The electronic component module is preferably an electronic component module constituting an electronic control unit (ECU: Electronic Control Unit). Electronic components such as semiconductor elements, resistor chips, capacitors, and external connection terminals are installed on electronic substrates such as wiring substrates, and electronic components formed by electrically connecting circuit substrates and each electronic component through conductive bonding portions such as solder are modularized, thereby preparing an electronic control unit. The electronic control unit is preferably an electronic control unit for aircraft and automobiles, and more preferably an electronic control unit related to a sensor.

[0102] As for the mounting body on which electronic components are mounted on the circuit board through the conductive adhesive part, in order to protect the electronic components, the mounting body is usually stored in a housing and integrated to form an electronic component module. In recent years, the miniaturization of the electronic component module is required. Instead of storing the electronic components in the housing, the electronic components themselves are sealed with thermoplastic resin to form an integrated electronic component module. The electronic component module is manufactured by arranging the electronic components in a metal mold for injection molding (in-mold molding). However, when using the previous coating agent, during injection molding, the heat of the molten thermoplastic resin is sometimes transferred to the electronic components, and the conductive adhesive parts such as the solder are remelted, and sometimes the electronic components are damaged by the partial remelting of the solder. In contrast, in the present invention, a uniform heat-insulating film can be formed by the coating agent, so that heat is difficult to be transferred to the solder, etc., and the damage of the electronic components can be suppressed. It should be noted that, in the present invention, sealing electronic components with thermoplastic resin means integrating or protecting electronic components, sensors, external connection terminals, etc. with thermoplastic resin, and there may be parts in substrates, sensors, cables, etc. that are not covered with thermoplastic resin.

[0103] The manufacturing method of the electronic component module is not particularly limited. The manufacturing method of the electronic component module preferably comprises the following steps. (1) A step of mounting the electronic component on the circuit substrate via the conductive adhesive portion. (2) A step of coating the conductive adhesive portion with the coating agent to form a film covering the conductive adhesive portion. (3) A step of sealing the electronic component on the circuit substrate using a thermoplastic resin (sealing thermoplastic resin).

[0104] Alternatively, the step (1) may be omitted to obtain a mounting body in which the electronic component is mounted on the circuit board via the conductive adhesive portion. Alternatively, the step (2') may be performed in which, in the mounting body in which the electronic component is mounted on the circuit board via the conductive adhesive portion, the conductive adhesive portion is coated with the coating agent to form a coating covering the conductive adhesive portion.

[0105] In the step (2), it is preferred that drying be performed to remove the solvent contained in the coating agent. The drying may be performed at room temperature (eg, around 25° C.) or by hot air drying.

[0106] The step (3) may or may not be performed. From the viewpoint of protecting electronic components and improving the reliability of the electronic component module, the step (3) is preferably performed. In the step (3), the electronic components on the circuit substrate are preferably sealed using the thermoplastic resin (sealing thermoplastic resin) by injection molding in a metal mold. The conductive adhesive portion on the circuit substrate is preferably sealed using the thermoplastic resin portion via the film. The film on the circuit substrate is preferably sealed using the thermoplastic resin portion. By using the coating agent of the present invention, even if injection molding is performed in a metal mold, remelting of the conductive adhesive portion and thermal degradation of the circuit substrate caused by the heat during the injection molding can be suppressed. By performing so-called in-mold molding, an electronic component module of a desired shape in which electronic components are sealed and integrated with thermoplastic resin can be manufactured.

[0107] The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0108] (Example 1)

[0109] A solution of a mixture of a thermoplastic resin and a solvent ("RF630" manufactured by Fuji Chemical Industry Co., Ltd. (20% by weight of rubber resin, 80% by weight of methylcyclohexane) was prepared. 40 parts by weight of hollow particles ("ADVANCELL HB2051" manufactured by Sekisui Chemical Industry Co., Ltd., porous hollow particles, material: polyacrylonitrile, specific gravity: 0.4, hollow ratio: 50% by volume, average particle size: 20 μm) were added to 100 parts by weight of the solution (20% by weight of rubber resin, 80% by weight of methylcyclohexane), and the mixture was stirred thoroughly to prepare a coating liquid (coating agent). Next, the obtained coating liquid was applied to a polyimide film using a wire rod coater, and the film was formed by drying the solution to evaporate the solvent.

[0110] (Example 2)

[0111] A solution of a mixture of a thermoplastic resin and a solvent ("V985-15E" manufactured by Ryoden Chemical Co., Ltd.) (15% by weight of a polyurethane resin and 85% by weight of methylcyclohexane) was prepared. 40 parts by weight of hollow particles ("ADVANCELL HB2051" manufactured by Sekisui Chemical Co., Ltd., porous hollow particles, material: polyacrylonitrile, specific gravity: 0.4, hollow ratio: 50% by volume, average particle size: 20 μm) were added to 100 parts by weight of the solution (15% by weight of a polyurethane resin and 85% by weight of methylcyclohexane), and the mixture was stirred thoroughly to prepare a coating solution. Next, the obtained coating solution was applied to a polyimide film using a wire rod coater, and the film was formed by drying the solution to evaporate the solvent.

[0112] (Example 3)

[0113] Toluene was further added to a mixture of a thermoplastic resin and a solvent (SANYU-REC "MX-208" (acrylic resin 24% by weight, toluene 76% by weight) to obtain a solution (acrylic resin 20% by weight, toluene 80% by weight). 19 parts by weight of hollow particles ("ADVANCELL HB2051" manufactured by Sekisui Chemical Co., Ltd., porous hollow particles, material: polyacrylonitrile, specific gravity: 0.4, hollow ratio: 50% by volume, average particle size: 20 μm) were added to 100 parts by weight of the obtained solution (acrylic resin 20% by weight, toluene 80% by weight), and the mixture was stirred thoroughly to prepare a coating liquid. Next, the obtained coating liquid was applied to a polyimide film using a wire rod coater, and the film was formed by drying the obtained solution to evaporate the solvent.

[0114] (Example 4)

[0115] Toluene was further added to a mixture of a thermoplastic resin and a solvent (SANYU-REC "MX-208" (acrylic resin 24% by weight, toluene 76% by weight) to obtain a solution (acrylic resin 16% by weight, toluene 84% by weight). 19 parts by weight of hollow particles ("ADVANCELL HB2051" manufactured by Sekisui Chemical Co., Ltd., porous hollow particles, material: polyacrylonitrile, specific gravity: 0.4, hollow ratio: 50% by volume, average particle size: 20 μm) were added to 100 parts by weight of the obtained solution (acrylic resin 16% by weight, toluene 84% by weight), and the mixture was stirred thoroughly to prepare a coating solution. Next, the obtained coating solution was applied to a polyimide film using a wire rod coater, and the film was formed by drying the obtained solution to evaporate the solvent.

[0116] (Example 5)

[0117] Prepare a solution of a mixture of a thermoplastic resin and a solvent ("RF630" manufactured by Fuji Chemical Industry Co., Ltd. (20% by weight of rubber resin, 80% by weight of methylcyclohexane). 18 parts by weight of hollow particles ("EXPANCEL 920DE40d30" manufactured by FILLITE Co., Ltd. of Japan, single-hole hollow particles, material: copolymer of acrylic acid and polyvinylidene chloride, specific gravity: 0.03, hollow ratio: 97% by volume, average particle size: 40 μm) are added to 100 parts by weight of the solution (20% by weight of rubber resin, 80% by weight of methylcyclohexane). Then, stir well to prepare a coating solution. Next, spread the obtained coating solution using release paper and apply it on a polyimide film at the same time, dry it and evaporate the solvent to form a film.

[0118] (Comparative Example 1)

[0119] A solution of a mixture of a thermoplastic resin and a solvent (SANYU-REC "MX-208" (acrylic resin 24% by weight, toluene 76% by weight) was prepared. 19 parts by weight of hollow particles ("ADVANCELL HB2051" manufactured by Sekisui Chemical Co., Ltd., porous hollow particles, material: polyacrylonitrile, specific gravity: 0.4, hollow ratio: 50% by volume, average particle size: 20 μm) were added to 100 parts by weight of the solution (acrylic resin 24% by weight, toluene 76% by weight), and the mixture was stirred thoroughly to prepare a coating solution. Next, the obtained coating solution was applied to a polyimide film using a wire rod coater, and the film was formed by drying the film to evaporate the solvent.

[0120] (Comparative Example 2)

[0121] A mixture of a thermoplastic resin and a solvent ("RF630" manufactured by Fuji Chemical Industry Co., Ltd. (20 wt % of rubber resin and 80 wt % of methylcyclohexane)) was prepared as a coating liquid, and the coating liquid was applied to the polyimide film using a wire bar coater and dried to evaporate the solvent, thereby forming a coating film.

[0122] (Comparative Example 3)

[0123] A mixture of a thermoplastic resin and a solvent ("V985-15E" manufactured by Ryoden Kasei Co., Ltd.) was prepared as a coating liquid. The coating liquid was applied to the polyimide film using a wire bar coater and dried to evaporate the solvent, thereby forming a coating film.

[0124] (Comparative Example 4)

[0125] A mixture of a thermoplastic resin and a solvent (SANYU-REC "MX-208" (acrylic resin 24 wt%, toluene 76 wt%)) was prepared as a coating liquid, and the coating liquid was applied to the polyimide film using a wire bar coater and dried to evaporate the solvent, thereby forming a coating film.

[0126] (evaluate)

[0127] (1) Viscosity of a composition containing a thermoplastic resin and a solvent contained in a coating agent at a weight ratio in the coating agent at 25°C

[0128] A composition containing a thermoplastic resin and a solvent contained in a coating agent at a weight ratio in the coating agent (a composition excluding hollow particles of the coating agent) is prepared. The composition is a solution in which the thermoplastic resin is dissolved in the solvent. The viscosity of the composition at 25° C. is measured using an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.).

[0129] (2) Thermal insulation (preventing solder from remelting)

[0130] The obtained coating solution was used to apply the substrate by dipping, and the substrate was dried to evaporate the solvent (volatilize), thereby forming a film, and the thickness of the film after solidification was measured. As a result, the thickness of the film formed by one dipping was 180 μm. In order to have a heat insulation property that does not cause solder remelting during injection molding in a film with a thickness of 180 μm, the thermal conductivity of the film needs to be less than 0.1200 W / m·K. The thermal conductivity of the film was measured by the transient hot line method.

[0131] The thermal insulation properties (solder remelting prevention properties) were determined based on the thermal conductivity of the film according to the following criteria.

[0132] [Criteria for judging heat insulation properties (solder remelting prevention properties)]

[0133] ○: Thermal conductivity of the film is 0.1200 W / m·K or less

[0134] ×: Thermal conductivity of the film exceeds 0.1200 W / m·K

[0135] The compositions and results are shown in Tables 1 and 2 below.

[0136] [Table 1]

[0137]

[0138] [Table 2]

[0139]

[0140] Explanation of symbols

[0141] 1…Electronics module

[0142] 2…Circuit board

[0143] 3…Conductive adhesive part

[0144] 4…Capsule

[0145] 5…Electronic components

[0146] 6…Thermoplastic resin part

Claims

1. A coating agent for forming a film in an electronic component module in which an electronic component is mounted on a circuit board via a conductive adhesive portion and the conductive adhesive portion is covered with a film, wherein: The coating agent comprises: Thermoplastic resins; a solvent that dissolves the thermoplastic resin; and Hollow particles, The content of the thermoplastic resin in 100 wt % of the total content of the thermoplastic resin and the solvent is 1.0 wt % or more and 22.0 wt % or less, The content of the hollow particles is 15.0 parts by weight or more and 50.0 parts by weight or less relative to 100 parts by weight of the total content of the thermoplastic resin and the solvent.

2. The coating agent according to claim 1, wherein The boiling point of the solvent is 130° C. or lower.

3. The coating agent according to claim 1 or 2, wherein The viscosity of the composition containing the thermoplastic resin and the solvent contained in the coating agent at a weight ratio in the coating agent at 25° C. is 1 mPa·s or more and 350 mPa·s or less.

4. The coating agent according to any one of claims 1 to 3, wherein The hollow particles have a hollow ratio of 40% by volume or more and 99% by volume or less.

5. The coating agent according to any one of claims 1 to 4, wherein The specific gravity of the hollow particles is 5.0 or less.

6. The coating agent according to any one of claims 1 to 5, wherein The material of the hollow particles includes poly(meth)acrylonitrile or (meth)acrylic resin.

7. The coating agent according to any one of claims 1 to 6, which is used to form the film in an electronic component module in which the electronic component is mounted on the circuit substrate via the conductive adhesive portion, the conductive adhesive portion is covered by the film, and the electronic component on the circuit substrate is sealed by a thermoplastic resin.

8. A method for manufacturing an electronic component module, comprising: A step of forming a coating, in which, in a mounted body in which an electronic component is mounted on a circuit board via a conductive adhesive portion, the conductive adhesive portion is coated with the coating agent according to any one of claims 1 to 6 to form a coating covering the conductive adhesive portion.

9. The method for manufacturing an electronic component module according to claim 8, further comprising: The step of mounting the electronic component on the circuit board via the conductive adhesive portion.

10. The method for manufacturing an electronic component module according to claim 8 or 9, further comprising: The sealing step is to seal the electronic components on the circuit board with a thermoplastic resin.

11. The method for manufacturing an electronic component module according to claim 10, wherein: The electronic components on the circuit board are sealed with the thermoplastic resin by injection molding in a metal mold.

Images