Coating method of mounting board, and manufacturing method of control device

Abstract

To provide a manufacturing method of a control device and a coating method of a mounting board which can sufficiently coat a mounted surface having unevenness with a coating film even if a used amount of a coating agent is comparatively small.SOLUTION: A coating method of a mounting board for coating a mounting board having a substrate and an element mounted on one surface side of the substrate with a coating film on a mounted surface where the element is mounted includes: the steps of: manufacturing a transfer mold where an uneven shape on the mounted surface of the mounting board is transferred; arranging a coating agent between the mounting board and the transfer mold, in a state in which a projection of the mounted surface in the mounting board is fit into a recess in the transfer mold where the projection is transferred; and curing the coating agent, and thereby forming a coating film coating the mounted surface of the mounting board.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to, for example, a coating method for a mounting substrate in which elements are mounted on one surface side of a substrate. The present invention also relates to, for example, a manufacturing method for a control device that manufactures a control device by coating the above-described mounting substrate.

Background Art

[0002] Conventionally, for example, a mounting substrate including a substrate and elements mounted on the substrate is known. The substrate is, for example, a printed circuit board, and the elements are, for example, semiconductor elements or the like. For this type of mounting substrate, for the purpose of, for example, moisture protection, the mounting surface, which is the surface on which the elements are mounted, is coated (covered) with a coating film. In this type of coating method, for example, a coating agent is simply applied to the mounting surface on the mounting substrate, and the applied coating agent is cured to form a coating film, and the mounting surface of the mounting substrate is covered with the coating film.

[0003] As a coating method for the mounting substrate as described above, for example, a method is known in which a coating agent (coating resin) applied to at least a part of an element (electronic component) is cured, and then the coating agent is further applied and cured so as to be overlaid (see Patent Document 1, etc.).

[0004] According to the method described in Patent Document 1, since the coating agent is applied a plurality of times, the coating agent can be applied relatively thickly in a desired range and cured.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the method described in Patent Document 1, since the coating amount is relatively large, an excessive amount of coating agent more than necessary is used. Further, due to the influence of the unevenness of the mounting surface, the coating on the convex portions in particular may be insufficient. Therefore, there is a demand for a method that can sufficiently cover a mounting surface having unevenness with a coating film even with a relatively small amount of coating agent.

[0007] In view of the above problems and the like, an object of the present invention is to provide a method for coating a mounting substrate and a method for manufacturing a control device that can sufficiently cover a mounting surface having unevenness with a coating film even when the amount of coating agent used is relatively small.

Means for Solving the Problems

[0008] To solve the above problems, a method for coating a mounting substrate according to the present invention is a method for coating a mounting substrate having a substrate and an element mounted on one surface side of the substrate, the method covering the mounting surface on which the element is mounted with a coating film, a step of producing a transfer mold in which the uneven shape on the mounting surface of the mounting substrate is transferred; a step of disposing a coating agent between the mounting substrate and the transfer mold in a state where the convex portions on the mounting surface of the mounting substrate are fitted into the concave portions in the transfer mold in which the convex portions are transferred; a step of forming a coating film covering the mounting surface of the mounting substrate by curing the coating agent; and is characterized by including the above steps.

[0009] A method for manufacturing a control device according to the present invention is a method for manufacturing a control device including a substrate, a mounting substrate having an element mounted on one surface of the substrate, and a coating film covering the mounting surface on which the element is mounted in the mounting substrate, a step of producing a transfer mold in which the uneven shape on the mounting surface of the mounting substrate is transferred; A step of disposing a coating agent between the mounting substrate and the transfer mold in a state where the convex portions on the mounting surface of the mounting substrate are fitted into the concave portions in the transfer mold onto which the convex portions are transferred; A step of forming a coating film that covers the mounting surface of the mounting substrate by curing the coating agent; A step of separating the control device in a state where the mounting surface of the mounting substrate is covered with the coating film and the transfer mold from each other; It is characterized by including the above.

Effect of the Invention

[0010] According to the coating method of the mounting substrate and the manufacturing method of the control device according to the present invention, even if the amount of the coating agent used is relatively small, the mounting surface having unevenness can be sufficiently covered with the coating film.

Brief Description of the Drawings

[0011]

Fig. 1A

Fig. 1B

Fig. 2

Fig. 3

Fig. 4

Fig. 5

Embodiments for Carrying Out the Invention

[0012] Hereinafter, an embodiment of the coating method of the mounting substrate according to the present invention will be described.

[0013] The coating method of the mounting substrate 10 of the present embodiment is a method of coating a mounting substrate 10 having a substrate 11 and an element 12 mounted on one surface side of the substrate 11 with a coating film 30 on the mounting surface where the element 12 is mounted. By implementing the coating method of the mounting substrate 10 of the present embodiment, the surface (mounting surface) of the mounting substrate 10 on which the element 12 is mounted is coated with the coating film 30, and the control device 1 is manufactured.

[0014] Specifically, the coating method of the mounting substrate 10 of the present embodiment includes a step of producing a transfer mold in which the concavo-convex shape on the mounting surface of the mounting substrate 10 is transferred (hereinafter, may be simply referred to as the transfer mold production step), and a step of disposing a coating agent between the mounting substrate 10 and the transfer mold in a state where the convex portions on the mounting surface of the mounting substrate 10 are fitted into the concave portions in the transfer mold in which the convex portions are transferred (hereinafter, may be simply referred to as the coating agent disposition step), and a step of forming a coating film 30 that covers the mounting surface of the mounting substrate 10 by curing the coating agent (hereinafter, may be simply referred to as the coating film formation step). According to the coating method of the mounting substrate 10 of the present embodiment, even if the amount of the coating agent used is relatively small, the mounting surface having concavo-convexities can be sufficiently covered with the coating film 30.

[0015] The mounting substrate 10 has at least a substrate 11 and an element 12 mounted on at least one surface of the substrate 11. The element 12 is mounted on at least one surface of the mounting substrate 10. At least one surface of the substrate 11 may have an electrical circuit wiring or an electronic circuit wiring formed thereon. In other words, the mounting substrate 10 may have an electrical circuit or an electronic circuit including the element 12.

[0016] The substrate 11 is plate-shaped. The substrate 11 may have a shape such as circular, rectangular, polygonal, or irregular when viewed in the thickness direction. Examples of the substrate 11 include a glass cloth epoxy substrate, a glass composite substrate, a paper phenol substrate, and a ceramic substrate.

[0017] The element 12 is not particularly limited as long as it is mounted on at least one surface of the substrate 11. One or a plurality of elements 12 may be mounted on one side of the substrate 11, or one or a plurality of elements 12 may be mounted on each of both surfaces of the substrate 11.

[0018] Examples of the element 12 include an IC package. In the IC package, lead electrodes extending outward from four sides or two sides of the rectangular element body 12a are mounted on the surface of the substrate 11 by soldering. Further, examples of the element 12 include passive elements such as a resistor (chip resistor, etc.), a capacitor (chip capacitor, etc.), an inductor (chip inductor, etc.), or a coil. The element 12 is mounted on the surface of the substrate 11 as, for example, a chip component or a lead component. The chip component has a rectangular chip shape, and electrodes disposed at the ends are electrically connected to the surface of the substrate 11 by soldering. The lead component has lead-shaped electrode terminals extending outward from near the ends, and the tip portions of these electrode terminals are mounted on the electrode surface on the substrate 11 by soldering (for example, an IC package such as QFP), or are pin-connected to the through-hole portion of the substrate 11 by soldering. Since the mounting substrate 10 has the element 12 arranged as described above with the above-described shape, the surface on which the element 12 is mounted has an uneven shape.

[0019] As shown in FIGS. 1A and 1B, for example, the element 12 has a plate-shaped element body 12a arranged along one surface of the substrate 11, and a lead bent portion 12b extending while bending from the element body 12a to the substrate 11. The lead bent portion 12b is, for example, a terminal. In FIGS. 1A and 1B, an IC package in which a plurality of leads are arranged along each of the four sides of the element body 12a is shown as an example of the element 12. Such an element 12 is a typical IC package in which an IC chip is encapsulated with epoxy, and is also referred to as a QFP. In such an element 12, a plurality of lead terminals for signals, power supply, or ground extend outward from the four sides of the element body 12a, and are further connected by soldering on the surface of the substrate 11. Generally, an IC chip mounted on a QFP often has a function of controlling the entire control device 1.

[0020] By the above coating method, in the mounting substrate 10 on which the element 12 is mounted on at least one side of the substrate 11, the side on which the element 12 is arranged will be covered with the coating film 30. Examples of the object to be covered include, for example, the element 12 (element body 12a or terminals, etc.), or circuit wiring on the substrate. Since the surface of the mounting substrate 10 on the side where the element 12 is arranged includes the surface of the substrate 11 and the surface of the element 12, it has an uneven shape. For example, on the surface of the mounting substrate 10, unevenness is formed by the lead bending portion 12b of the above element 12. Even if the coating agent is applied by a general method, liquid dripping occurs at the convex portions, and the coating film after curing becomes thin, and the insulation of the coating film may not necessarily be sufficiently ensured. Liquid pooling may occur in the concave portions or around the substrate connection portions, and the coating film after curing may become too thick. Also, it is relatively difficult to spread the coating agent over the back surface of the mounting substrate 10 by utilizing the fluidity of the coating agent. On the other hand, by the coating method of the present embodiment, even convex or concave portions can be well covered. For example, even the lead bending portion 12b (terminal) of the element 12 can be sufficiently covered by the coating film 30. And by implementing the above coating method, a control device 1 in which at least a part of the mounting substrate 10 is covered with a coating film is manufactured.

[0021] Examples of the control device 1 include a large-capacity data processing board on which a large-scale integrated circuit (LSI chip) is mounted, a board on which an application-specific integrated circuit (ASIC) is mounted, or a power board for inverter control. More specifically, examples of the control device 1 include a control board used for precision equipment, a power control board mounted on automobiles, bicycles, railways, airplanes, ships, etc., an image control board or an audio processing control board used for mobile devices (such as mobile phones, digital cameras, digital video cameras, etc.), outdoor devices (such as water heaters, outdoor air conditioners, etc.), a power control board or a sensor control board used for water-related devices such as washing machines, bidets with warm water washing function, or dishwashers, or a switch control board.

[0022] In the above-described transfer mold manufacturing process, for example, a transfer mold Y is manufactured by curing a curable resin X having fluidity. For example, as shown in FIG. 2, the mounting surface of the mounting substrate 10 may be immersed in the curable resin X having fluidity, and in this state, the curable resin X may be cured by a curing process. By separating the mounting substrate 10 from the cured product of the curable resin, a transfer mold Y formed of a cured body can be obtained.

[0023] Examples of the curable resin having fluidity include a thermosetting resin cured by heat treatment, or a moisture-curing resin cured by moisture in the air.

[0024] Also, examples of the curable resin having fluidity include a curable silicone resin, a curable fluorine-containing resin, or an epoxy resin. As the curable resin, a curable silicone resin is preferable in terms of better releasability in the release process described later.

[0025] For example, in the above-described transfer mold manufacturing process, a transfer mold is manufactured by curing a curable composition containing a curable resin and a particulate light-scattering material while transferring the uneven shape of the mounting substrate 10 to the curable composition. Specifically, in the above-described transfer mold manufacturing process, a curable composition containing a curable silicone resin and particulate light scattering material may be semi-cured, and while transferring the uneven shape of the mounting substrate 10 to the semi-cured curable composition, the curable composition may be cured to produce a transfer mold. By producing a transfer mold obtained by curing a curable composition containing a light scattering material, when curing a coating agent by light irradiation in a coating film forming process described later, there is an advantage that the irradiated light can be dispersed (to be described in detail later).

[0026] Examples of the particulate light scattering material include glass beads or silicone resin particles. The particulate light scattering material can scatter light such as infrared rays, visible light, or ultraviolet rays. The particle diameter of the light scattering material may be, for example, 50 μm or more and 250 μm or less.

[0027] In the above-described transfer mold manufacturing process, a transfer mold (cured product) overlapping one side of a plate-shaped support may be produced.

[0028] The above-described plate-shaped support may be light-transmissive so as to transmit irradiation light that can be adopted in a later coating film forming process. Examples of the light-transmissive plate-shaped support include a glass plate and a quartz plate. Since the light-transmissive plate-shaped support adheres to the transfer mold, the shape of the transfer mold can be supported by the plate-shaped support. Therefore, the shape of the transfer mold can be stabilized.

[0029] In the above-described transfer mold manufacturing process, in order to suppress deterioration of the transfer mold due to ultraviolet rays, irradiation of the transfer mold with ultraviolet rays may be suppressed by an ultraviolet ray preventing film or the like. Further, irradiation of the transfer mold with ultraviolet rays may be suppressed by applying or spraying a liquid containing an ultraviolet ray scattering agent or an ultraviolet ray absorber to the transfer mold. The timing of using the above-described ultraviolet ray preventing film or a liquid containing an ultraviolet ray scattering agent or an ultraviolet ray absorber is not particularly limited.

[0030] In the above-described transfer mold manufacturing process, a transfer mold may be manufactured as described above with a flexible thin film disposed between the curable resin having fluidity and the mounting surface of the mounting substrate 10. After the curing treatment as described above, a transfer mold from which the thin film and the mounting substrate 10 have been removed is obtained. By using the above-described thin film, the thickness of the thin film can correspond to the thickness of the coating agent in the subsequent coating agent placement step. Therefore, the coating film 30 can be more reliably manufactured in the subsequent coating film formation step.

[0031] As the above-described thin film, a polymethyl methacrylate-based resin, a polyolefin-based resin, or the like can be used. The thickness of the thin film is, for example, 50 μm or more and 500 μm or less. As the thin film, a commercially available release film having flexibility can be used. More specifically, as the polymethyl methacrylate-based resin, "Acrypren HBS006H" (manufactured by Mitsubishi Chemical Corporation) or the like can be used, and as the polyolefin-based resin, "DECOFIT #100-Q01CK" (manufactured by Toray Industries, Inc.) or the like can be used. If necessary, a thin film formed by laminating a plurality of release films may be employed. When using the thin film as described above, the thin film may be bonded to the mounting surface of the control device having unevenness by, for example, the apparatus disclosed in Japanese Patent No. 7126352.

[0032] Also, in the above-described transfer mold manufacturing process, after forming a coating adhesion film on the mounting surface of the mounting substrate 10, a transfer mold may be manufactured as described above. After the curing treatment as described above, a transfer mold from which the coating adhesion film and the mounting substrate 10 have been removed is obtained. Also, the coating adhesion film is peeled off from the mounting surface of the mounting substrate 10. By manufacturing the transfer mold after forming the above-described coating adhesion film, the thickness of the coating adhesion film can correspond to the thickness of the coating agent in the subsequent coating agent placement step. Therefore, the coating film 30 can be more reliably manufactured in the subsequent coating film formation step.

[0033] The material of the above-mentioned coating adhesion film is not particularly limited, but resins that can exhibit mold release properties, such as silicone resin or polyolefin resin, are preferable. The thickness of the coating adhesion film is, for example, 50 μm or more and 300 μm or less.

[0034] On the other hand, in the transfer mold manufacturing process of the present embodiment, a transfer mold may be manufactured using a so-called 3D printer. As the 3D printer, a general one can be used. For example, by scanning the three-dimensional shape of the mounting surface of the mounting substrate 10 to be coated, the unevenness of the mounting surface of the mounting substrate 10 is stored in the 3D printer. Based on the stored three-dimensional information, a transfer mold is manufactured by the 3D printer.

[0035] In the present embodiment, in the coating agent arrangement step, with the convex portions on the mounting surface of the mounting substrate 10 fitted into the concave portions of the transfer mold onto which the convex portions are transferred, as shown in FIG. 3, a coating agent Q is arranged between the mounting substrate 10 and the transfer mold Y. For example, the mounting substrate 10 and the transfer mold Y are arranged such that the mounting surface of the mounting substrate 10 faces downward and at least a part of the concave surface of the transfer mold Y faces upward. The coating agent Q is applied to the concave surface of the transfer mold Y, and then the mounting surface of the mounting substrate 10 is pressed against the transfer mold Y. As the application method, for example, a conformal coating method, a spray coating method, or a brush coating method can be adopted. In this way, the coating agent Q can be arranged between the mounting substrate 10 and the transfer mold Y (the first method). On the other hand, for example, with the convex portions on the mounting surface of the mounting substrate 10 fitted into the concave portions of the transfer mold Y onto which the convex portions are transferred, the coating agent Q is supplied between the mounting substrate 10 and the transfer mold Y. The supply of the coating agent Q can be carried out using capillary action (the second method). If necessary, both of the above-mentioned first method and second method can be carried out.

[0036] The coating agent has fluidity. The viscosity of the coating agent at 25°C may be, for example, 10 [mPa·s] or more and 10,000 [mPa·s] or less. Thereby, a coating film 30 with less variation in film thickness can be formed. The viscosity of the above coating agent is measured, for example, under the following measurement conditions. [Examples of Viscosity Measurement Conditions] · Viscometer: Type E (plate type), for example, "RE-85R" manufactured by Toki Sangyo · Temperature: 25°C · Cone and plate: 1.34° R24 · Rotation speed: 1 to 100 rpm

[0037] The viscosity of the coating agent is preferably 20 [mPa·s] or more. As the viscosity of the coating agent increases, the fluidity of the coating agent before curing becomes lower. Therefore, even on the back side (opposite side of the mounting surface) of the mounting substrate 10, the thickness of the coating film can be closer to being uniform. The viscosity of the coating agent is preferably 5,000 [mPa·s] or less, and more preferably 1,000 [mPa·s] or less. When the viscosity of the coating agent decreases, there is an advantage that the coating agent can be more reliably disposed between the mounting substrate 10 and the transfer mold Y by utilizing the capillary phenomenon, which will be described in detail later.

[0038] The coating agent is not particularly limited as long as it can be cured by a curing treatment. Examples of the curing treatment include heat treatment, light irradiation treatment, moisture exposure treatment, and changes in the anaerobic state of the surrounding environment.

[0039] The coating agent may be, for example, a thermosetting coating agent that is cured by heat treatment. The thermosetting coating agent includes, for example, thermosetting resins. Examples of the thermosetting resin include epoxy resins.

[0040] The coating agent may be, for example, a photocurable coating agent that is cured by irradiation with light. Examples of the light to be irradiated include ultraviolet light, infrared light, or visible light. The photocurable resin coating agent may contain, for example, a photocurable resin or a radically polymerizable monomer. The photocurable resin has, for example, a radically polymerizable double bond in the molecule. The photocurable resin can be cured, for example, when radicals are generated by light irradiation. The radically polymerizable monomer may be, for example, an alkyl (meth)acrylate.

[0041] The coating agent may be, for example, a moisture-curable coating agent that cures by moisture. The moisture-curable coating agent may contain, for example, a moisture-curable resin. The moisture-curable resin has, for example, an isocyanate group in the molecule. The moisture-curable resin can be cured, for example, when the isocyanate groups react with each other by water.

[0042] The coating agent may be, for example, an anaerobic-curing coating agent that cures in an anaerobic state. The anaerobic-curing coating agent may contain, for example, an anaerobic-curable resin. The anaerobic-curable resin has, for example, a radically polymerizable unsaturated double bond in the molecule. The anaerobic-curable resin can be cured when the unsaturated double bonds in the molecule undergo a crosslinking reaction in an anaerobic state.

[0043] The coating agent is preferably a coating agent that cures by at least two of the above heat treatment, the above light irradiation, the above moisture, and the above anaerobic state, and more preferably a coating agent that cures by the above light irradiation and at least one of the above heat treatment, the above moisture, and the above anaerobic state.

[0044] As the coating agent, a photocurable coating agent that cures at least by light irradiation is preferable in that a simple light irradiation treatment can be adopted as a curing treatment in the coating film forming step described in detail later. The photocurable coating agent may be, for example, a composition containing at least one of a photocurable resin and a radically polymerizable monomer that cures by a polymerization reaction, and further containing a photoinitiator.

[0045] The photocurable resin that can be contained in the coating agent includes, for example, a radically polymerizable oligomer and the like. As the photocurable resin, commercially available products can be adopted.

[0046] The coating agent contains, as a radically polymerizable monomer, for example, an alkyl (meth)acrylate monomer. In this specification, the notation “(meth)acrylate” includes both “acrylate” and “methacrylate”.

[0047] Examples of the alkyl (meth)acrylate monomer include a saturated linear alkyl (meth)acrylate monomer, a saturated branched-chain alkyl (meth)acrylate monomer, or a saturated cycloalkyl (meth)acrylate monomer.

[0048] The hydrocarbon structure of the saturated linear alkyl (meth)acrylate monomer may be a saturated linear alkyl structure. Specifically, examples of the saturated linear alkyl (meth)acrylate monomer include n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and the like.

[0049] The hydrocarbon structure of the saturated branched-chain alkyl (meth)acrylate monomer may be a saturated branched-chain alkyl structure, and may be an iso structure, a sec structure, a neo structure, or a tert structure. Specifically, examples of the saturated branched-chain alkyl (meth)acrylate monomer include isoheptyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like.

[0050] The hydrocarbon structure of the saturated cycloalkyl (meth)acrylate monomer may include a saturated cyclic alkyl structure. Specifically, examples of the saturated cycloalkyl (meth)acrylate monomer include isobornyl (meth)acrylate (containing a norbornane structure), dicyclopentadiene oxyethyl (meth)acrylate (containing a norbornane structure), dicyclopentanyl (meth)acrylate (containing a norbornane structure), dicyclopentenyl oxyethyl (meth)acrylate (containing a norbornane structure), adamantyl (meth)acrylate, and the like.

[0051] In addition, examples of the radical polymerizable monomer include a monofunctional (meth)acrylate monomer having one polymerizable double bond in the molecule, a polyfunctional (meth)acrylate monomer having a plurality of polymerizable double bonds in the molecule, and the like. Examples of the monofunctional (meth)acrylate monomer include, in addition to those described above, phenyloxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, benzyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, and the like. Examples of the polyfunctional (meth)acrylate monomer include neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6 - hexanediol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethylene oxide - modified bisphenol A di(meth)acrylate, ethylene oxide - modified trimethylolpropane tri(meth)acrylate, ethylene oxide - modified pentaerythritol tetra(meth)acrylate, tris[(meth)acryloxyethyl] isocyanurate, ethylene oxide - modified dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate, and the like.

[0052] The above radical polymerizable monomers can be used alone or in combination of two or more. As the above radical polymerizable monomers, commercially available products can be used.

[0053] The photoinitiator is not particularly limited as long as it is a compound that generates radicals upon irradiation with light (such as ultraviolet light). Examples of the photoinitiator include acetophenone-based photoinitiators, benzoin-based photoinitiators, benzophenone-based photoinitiators, thioxanthone-based photoinitiators, acylphosphine oxide-based photoinitiators, and the like. Commercially available products can be used as the photoinitiator.

[0054] When the above coating agent is cured not only by light irradiation but also by moisture (humidity) in the air, the above coating agent may contain an isocyanate monomer. Examples of the isocyanate monomer include aromatic diisocyanate monomers, alicyclic diisocyanate monomers, aliphatic diisocyanate monomers, etc. These monomers may have 2 to 4 isocyanate groups in the molecule. Examples of the aromatic diisocyanate monomer include monomers such as tolylene diisocyanate, diphenylmethane diisocyanate, diphenylpropane diisocyanate, triphenylmethane diisocyanate, phenylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate. Examples of the alicyclic diisocyanate monomer include monomers such as hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, cyclohexylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), 3-isocyanatoethyl-3,5,5-trimethylcyclohexyl isocyanate, 3-isocyanatoethyl-3,5,5-triethylcyclohexyl isocyanate, etc. Examples of the aliphatic diisocyanate monomer include hexamethylene diisocyanate monomer, etc. Note that the isocyanate monomer may be an adduct-modified product, biuret-modified product, isocyanurate form, or polymeric form of at least any one of the above monomers. These monomers can be used singly or in combination of two or more kinds.

[0055] When the above coating agent is cured not only by light irradiation but also in an anaerobic state, in addition to the above radical polymerizable monomer, the above coating agent may further contain a reducing agent such as saccharin, an organic peroxide, or an amine compound such as a secondary amine or a tertiary amine.

[0056] In the present embodiment, in the coating film forming step, with the convex portions on the mounting surface of the mounting substrate 10 fitted into the concave portions in the transfer mold Y onto which the convex portions are transferred, the coating agent disposed between the mounting substrate 10 and the transfer mold Y is cured. The cured coating agent becomes a coating film 30 that covers the surface of the mounting substrate 10.

[0057] The coating film 30 is a cured product obtained by curing the above-described coating agent by a curing treatment. In other words, the coating film 30 is formed by curing the coating agent disposed between the mounting substrate 10 and the transfer mold Y.

[0058] The thickness of the coating film 30 may be, for example, 50 μm or more and 200 μm or less.

[0059] In the coating film forming step, when the coating agent is a thermosetting coating agent, the thermosetting coating agent disposed between the mounting substrate 10 and the transfer mold Y is cured by heat treatment. In the heat treatment, for example, temperature conditions of 60°C or more and 150°C or less and a heating time of 20 minutes or more and 2 hours or less are adopted.

[0060] In the coating film forming step, when the coating agent is a photocurable coating agent, the photocurable coating agent disposed between the mounting substrate 10 and the transfer mold Y is cured by irradiation with light. As the light to be irradiated, ultraviolet rays are preferable in terms of relatively high safety for the human body and relatively high irradiation energy.

[0061] In the coating film forming step, the light transmitted through the transfer type Y may be irradiated onto the coating agent to form a coating film from such a coating agent. In other words, with the mounting substrate 10 fitted into the transfer type Y, light may be irradiated onto the coating agent from the transfer type side. In addition, light may be irradiated onto the surface of the mounting substrate 10 on the side opposite to the mounting surface, and a coating film may be formed on the opposite surface.

[0062] In the coating film forming step, by irradiating the coating agent with light such as ultraviolet rays, the photoinitiator in the coating agent starts a radical reaction, and the above-described radical polymerizable monomer and the like undergo a polymerization reaction, and the curing of the coating agent proceeds.

[0063] In the coating film forming step, as a light source for irradiating the coating agent with ultraviolet rays, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, an LED lamp, or the like can be used. As the irradiation intensity, for example, 10~10,000 mW / cm 2 can be adopted. The energy to be irradiated is, for example, 100 mJ / cm 2 or more and 10,000 mJ / cm 2 or less.

[0064] In the coating film forming step, the orientation of the mounting surface when irradiating light (the orientation of the surface of the mounting substrate 10 covered with the coating agent) is not particularly limited. For example, light may be irradiated onto the coating agent in a state where the surface of the mounting substrate 10 covered with the coating agent faces either upward or downward, or light may be irradiated onto the coating agent in a state where the surface of the mounting substrate 10 covered with the coating agent faces laterally.

[0065] For example, as shown in FIG. 4, in the coating film forming step, light L is irradiated onto the surface of the mounting substrate 10 on the side opposite to the mounting surface (first irradiation), and the coating agent on the opposite surface is cured to form a coating film 30. Next, the mounting surface of the mounting substrate 10 is irradiated with light L (second irradiation) to cure the coating agent on the mounting surface and form a coating film 30. In the second irradiation, the light transmitted through the transfer mold Y is irradiated onto the coating agent on the mounting surface. Therefore, the transfer mold Y is preferably light-transmissive as described above. Further, when the transfer mold Y contains the particulate light-scattering material described above, the light passing through the transfer mold Y is sufficiently scattered, so that it easily reaches not only the surface of the convex portion but also the surface of the concave portion of the mounting surface. Thus, the coating agent on the surface of the concave portion of the mounting surface can be sufficiently cured. Therefore, the surface of the concave portion of the mounting surface can be sufficiently covered with the coating film 30.

[0066] The time for irradiating light in the coating film forming step is not particularly limited as long as the coating agent can be sufficiently cured. By irradiating light having stronger energy, the irradiation time can be made shorter.

[0067] In the coating film forming step, when the coating agent is a moisture-curing type coating agent, the moisture-curing type coating agent disposed between the mounting substrate 10 and the transfer mold Y can be cured by moisture in the air. When the curing reaction proceeds by moisture (humidity) in the air, for example, it is left in the air for several hours to several days. In this case, the temperature of the air left is preferably 20 to 40°C, and the humidity of the air is preferably 40 to 90RH%.

[0068] In the coating film forming step, when the coating agent is an anaerobic-curing type coating agent, the anaerobic-curing type coating agent disposed between the mounting substrate 10 and the transfer mold Y is cured in an anaerobic state.

[0069] As described above, the element 12 mounted on the substrate 11 has, for example, a plate-shaped element body 12a and a lead bending portion 12b that extends while bending from the element body 12a to the substrate 11. Since the lead bending portion 12b of the element 12 has a relatively complex shape, the mounting surface of the mounting substrate 10 has a complex uneven shape. Therefore, simply applying a coating agent to the mounting surface of the mounting substrate 10 may cause dripping of the liquid or insufficient wet spreading of the liquid, so that the surface in the recess of the lead bending portion 12b cannot necessarily be sufficiently covered with the coating agent. Therefore, there is a possibility that the coating film 30 may not necessarily be sufficiently formed on the surface of the lead bending portion 12b on the mounting surface. On the other hand, by implementing the coating method of the present embodiment, the coating film 30 can be sufficiently formed also on the surface of the lead bending portion 12b on the mounting surface having a relatively complex shape.

[0070] The coating method of the present embodiment may further include a step of separating from each other the control device 1 in a state where the mounting surface of the mounting substrate 10 is covered with the coating film 30 and the transfer mold Y (referred to as a mold release step). When the peeling step is performed, for example, as shown in FIG. 5, the control device 1 in which the surface of the mounting substrate 10 is covered with the coating film 30 can be obtained.

[0071] Subsequently, an embodiment of the manufacturing method of the control device according to the present invention will be described.

[0072] The manufacturing method of the control device 1 of the present embodiment is a manufacturing method of a control device including a substrate 11, a mounting substrate 10 having an element 12 mounted on one surface of the substrate 11, and a coating film 30 covering the mounting surface of the element 12 on the mounting substrate 10, a step of producing a transfer mold in which the uneven shape on the mounting surface of the mounting substrate 10 is transferred (the above transfer mold production step), A step of disposing a coating agent between the mounting substrate 10 and a transfer mold in a state where a convex portion on the mounting surface of the mounting substrate 10 is fitted into a concave portion in the transfer mold onto which the convex portion has been transferred (the above-described coating agent disposing step); A step of forming a coating film 30 that covers the mounting surface of the mounting substrate 10 by curing the coating agent (the above-described coating film forming step); A step of separating from each other the control device 1 in a state where the mounting surface of the mounting substrate 10 is covered with the coating film 30 and the transfer mold (the above-described mold releasing step).

[0073] The method for manufacturing a control device according to the present embodiment can be implemented by a method similar to the above-described coating method for a mounting substrate. By the method for manufacturing a control device according to the present embodiment, for example, a semiconductor control device in which an electric circuit or a mounting substrate 10 having an electric circuit is covered with a coating film 30 can be manufactured.

[0074] The method for manufacturing a control device according to the present embodiment and the coating method for a mounting substrate are as exemplified above, but the present invention is not limited to the method for manufacturing a control device and the coating method for a mounting substrate exemplified above. That is, various forms used in a general method for manufacturing a control device and a coating method for a mounting substrate can be adopted as long as the effects of the present invention are not impaired.

[0075] The matters disclosed by this specification include the following. (1) A coating method for a mounting substrate that coats a mounting substrate having a substrate and an element mounted on one surface side of the substrate with a coating film on the mounting surface on which the element is mounted, A step of producing a transfer mold in which the concavo-convex shape on the mounting surface of the mounting substrate is transferred; A step of disposing a coating agent between the mounting substrate and the transfer mold in a state where a convex portion on the mounting surface of the mounting substrate is fitted into a concave portion in the transfer mold onto which the convex portion has been transferred; A step of forming a coating film that covers the mounting surface of the mounting substrate by curing the coating agent. A method for coating a mounting substrate, comprising: (2) The coating agent is a photocurable coating agent that cures by irradiation with light. In the step of forming the coating film, the photocurable coating agent is cured by irradiation with the light. The method for coating a mounting substrate according to (1) above. (3) The coating agent is a moisture-curable coating agent that cures by moisture. In the step of forming the coating film, the moisture-curable coating agent is cured by the moisture. The method for coating a mounting substrate according to (1) or (2) above. (4) The coating agent is an anaerobic-curable coating agent that cures in an anaerobic state. In the step of forming the coating film, the anaerobic-curable coating agent is cured in the anaerobic state. The method for coating a mounting substrate according to any one of (1) to (3) above. (5) In the step of producing the transfer mold, a curable composition containing a curable silicone resin and a particulate light-scattering material is brought into a semi-cured state, and while transferring the uneven shape of the mounting substrate to the semi-cured curable composition, the curable composition is cured to produce the transfer mold. The method for coating a mounting substrate according to (2) above. (6) The mounting substrate has an electric circuit or an electronic circuit including the element. The method for coating a mounting substrate according to any one of (1) to (5) above. (7) A method for manufacturing a control device, comprising a substrate and a mounting substrate having an element mounted on one surface of the substrate, and a coating film that covers the mounting surface of the mounting substrate on which the element is mounted. A step of producing a transfer mold in which an uneven shape on the mounting surface of the mounting substrate is transferred. A step of producing a transfer mold in which an uneven shape on the mounting surface of the mounting substrate is transferred. A step of disposing a coating agent between the mounting substrate and the transfer mold in a state where the convex portions on the mounting surface of the mounting substrate are fitted into the concave portions in the transfer mold onto which the convex portions are transferred; A step of forming a coating film that covers the mounting surface of the mounting substrate by curing the coating agent; A step of separating the control device in a state where the mounting surface of the mounting substrate is covered with the coating film and the transfer mold from each other; A method for manufacturing a control device, including the above steps.

Example

[0076] Next, the present invention will be described in more detail by experimental examples, but the present invention is not limited thereto.

[0077] <Mounting substrate> As the mounting substrate, a semiconductor mounting substrate on which semiconductor elements are mounted was used. Such a semiconductor mounting substrate includes, for example, as shown in FIGS. 1A and 1B, a rectangular element body and a bent portion (such as a terminal) extending from the element body to the substrate. Therefore, unevenness is formed on the mounting surface of the semiconductor mounting substrate by the bent portion and the periphery of the bent portion.

[0078] <Raw materials for the coating agent (type using both ultraviolet curing and anaerobic curing)> A coating agent with a viscosity of 700 mPa·s was prepared by mixing the following raw materials. The viscosity was measured at 25°C and 10 rpm using a rotor with a diameter of 30 mm and an angle of 1.34° of the E-type viscometer "RE-80E" manufactured by Toki Sangyo Co., Ltd. · Photo-curable resin: 100 g Product name "UA-290TM", manufactured by Shin-Nakamura Chemical Co., Ltd. · Radical polymerizable monomer: 153 g Isobornyl acrylate (commercial product, containing 100 ppm of MEHQ) · Photoinitiator: 5.1 g [[ID=۳۸]]Product name "Omnirad BMS", manufactured by IGM RESINS · Photopolymerization accelerator: 2.5 g Ethyl dimethylaminobenzoate · Photo sensitizer: 1.3 g Product name "KAYACURE DETX-S" manufactured by Nippon Kayaku Co., Ltd. · Organic peroxide (for anaerobic curing): 1.3 g Containing 70% t-butyl hydroperoxide · Saccharin (for anaerobic curing): 1.3 g · Fluorescent dye for resin formation confirmation Product name "Irganox 1010" manufactured by BASF Japan <Raw materials for transfer-type curable resin> · Silicone resin (set of main agent and curing agent) Product name "Transparent silicone for mold taking" manufactured by Box Modeling Village · Light scattering material Glass beads (with a diameter in the range of 0.105 mm to 0.125 mm) <Substrate for evaluation> Product name "PIC877A Module Ver.2" manufactured by Akizuki Electronics Co., Ltd.

[0079] (Test Examples 1 and 2) Under each condition shown in Table 1, the transfer-type manufacturing process, the coating agent placement process, and the coating film formation process were carried out to manufacture a control device. In other words, the mounting surface of the mounting substrate was covered with a coating agent and coated with a coating film by a curing treatment.

[0080] <Transfer-type manufacturing process> After mixing the above silicone resin main agent and curing agent, glass beads were added as necessary. The stirred mixture was sufficiently stirred by a Shinchi-made planetary mixer (product name "Cheap Tarou for foaming"). The stirred mixture was put into an aluminum cup with a diameter of 60 mm and held at room temperature for 2 hours. After confirming that the cured mixture had appropriate elasticity, the coated surface (surface) of the above mounting substrate was turned downward, and the entire mounting substrate was submerged in the mixture while keeping the surface direction of the mounting substrate horizontal. After allowing the curing to proceed for 24 hours with the mounting substrate submerged, the mounting substrate was removed to produce a transfer mold.

[0081] <Coating agent placement process> The coated surface of the mounting substrate was turned downward, and the mounting substrate was fitted into the inner space of the transfer type described above. After that, the coating agent was injected only through the gap along one side of the rectangular element body, and the coated surface of the mounting substrate was covered with the coating agent using the capillary phenomenon. At this time, the coating agent that came out of the gap was confirmed near each side of the rectangular element body. Further, the coating agent was applied to the back surface of the mounting substrate.

[0082] <Coating Film Formation Step> The coating agent covering the mounting substrate was cured by a curing process. Specifically, ultraviolet rays were irradiated from the back side of the mounting substrate with a 500W UV lamp so that the integrated light quantity became the light intensity of 3 J / cm 2 Next, ultraviolet rays were irradiated from the front surface side (transfer type side) of the mounting substrate so that the integrated light quantity became the light intensity of 10 J / cm 2 to perform a curing process, and the coating agent was cured to form a coating film.

[0083] <Release Step> The coating film covering the mounting substrate was peeled off from the transfer type. Thereby, a control device in which the mounting surface of the mounting substrate was covered with the coating film was manufactured.

[0084]

Table 1

[0085] (Spray Method, Conventional Method) Using a spray device, the coating agent prepared as described above was atomized and applied to the front and back surfaces of the mounting substrate. The mounting substrate was placed horizontally, and the coating agent was applied so that the thickness of the coating film became 200 μm.

[0086] As shown below, the control devices (hereinafter referred to as chip resistors) manufactured in each test example were evaluated. [Observation with a Microscope] While irradiating with a handy black light as a light source, the adhesion state of the coating film was observed with a microscope manufactured by KEYENCE. Specifically, the adhesion state of the coating film was observed at the terminal lead portions of the QFP arranged along each side of the four sides of the rectangular chip resistor, and at the side portions of the chip resistor (the surface perpendicular to the horizontal plane of the substrate). [Measurement of Coating Film Thickness] The thicknesses of the coating film were measured at the central portion (flat portion) of the chip resistor and at the terminal lead portion (terminal portion) of the QFP, respectively. Specifically, the thickness at the central portion (flat portion) of the chip resistor was measured by the focus depth method using a macroscope. On the other hand, for the terminal lead portion of the chip resistor, the coating film thicknesses at two locations were measured, namely, at the lead bending shoulder portion (indicated by S in FIG. 1B) where the coating agent is likely to drip, and at the lead leg portion (indicated by T in FIG. 1B) where the dripped liquid is likely to accumulate. As the measuring instrument, "Optical Microscope Film Thickness Meter OPTM - A3" manufactured by Otsuka Electronics Co., Ltd. was used. The results are shown in Table 2.

[0087]

Table 2

[0088] As can be understood from the evaluation results shown in Table 2, by manufacturing a control device by the manufacturing method corresponding to the embodiment of the present invention, the mounting surface having unevenness can be sufficiently coated with a coating film using a relatively small amount of coating agent. In Test Example 2 using a transfer type containing a particulate light scattering material, the mounting surface could be coated more sufficiently.

Industrial Applicability

[0089] The coating method for the mounting substrate and the manufacturing method for the control device of the present invention are suitably used, for example, for manufacturing a control device that is moisture - proofed by a coating film.

Explanation of Reference Numerals

[0090] 1: Control device, 10: Mounting substrate, 11: Substrate, 12: Element, 12a: Element body, 12b: Lead bending part (terminal), 30: Coating film.

Claims

1. A method for coating a mounting substrate having a substrate and an element mounted on one surface side of the substrate, the method comprising coating, with a coating film, the mounting surface on which the element is mounted, the method comprising: a step of producing a transfer mold having the uneven shape on the mounting surface of the mounting substrate transferred thereto; a step of disposing a coating agent between the mounting substrate and the transfer mold in a state where the convex portions on the mounting surface of the mounting substrate are fitted into the concave portions in the transfer mold in which the convex portions are transferred; a step of forming a coating film that covers the mounting surface of the mounting substrate by curing the coating agent; A method for coating a mounting substrate, including the above steps.

2. The coating agent is a photocurable coating agent that cures by irradiation with light, In the step of forming the coating film, the photocurable coating agent is cured by irradiation with light. The method for coating a mounting substrate according to claim 1.

3. The coating agent is a moisture-curable coating agent that cures by moisture, In the step of forming the coating film, the moisture-curable coating agent is cured by the moisture. The method for coating a mounting substrate according to claim 1.

4. The coating agent is an anaerobic-curable coating agent that cures in an anaerobic state, In the step of forming the coating film, the anaerobic-curable coating agent is cured in the anaerobic state. The method for coating a mounting substrate according to claim 1.

5. In the step of producing the transfer mold, a curable composition containing a curable silicone resin and a particulate light-scattering material is brought into a semi-cured state, and while transferring the uneven shape of the mounting substrate to the semi-cured curable composition, the curable composition is cured to produce the transfer mold. The method for coating a mounting substrate according to claim 2.

6. The mounting substrate has an electric circuit or an electronic circuit including the element. The method for coating a mounting substrate according to any one of claims 1 to 5.

7. A method for manufacturing a control device including a substrate, a mounting substrate having an element mounted on one surface of the substrate, and a coating film covering the mounting surface of the mounting substrate on which the element is mounted, the method comprising: a step of producing a transfer mold having the uneven shape on the mounting surface of the mounting substrate transferred thereto; A step of disposing a coating agent between the mounting substrate and the transfer mold in a state where the convex portions on the mounting surface of the mounting substrate are fitted into the concave portions in the transfer mold onto which the convex portions are transferred; A step of forming a coating film covering the mounting surface of the mounting substrate by curing the coating agent; A step of separating the control device in a state where the mounting surface of the mounting substrate is covered with the coating film and the transfer mold from each other; A method for manufacturing a control device, including the above steps.

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