Electronic component mounting substrate, method for producing the same, electronic component coating sheet, and laminated sheet

Abstract

To provide: an electronic component coating sheet capable of forming a coating layer of excellent quality that can improve breakage and the occurrence of wrinkles while suppressing deviation of a coating position; an electronic component mounting substrate having the coating layer; and a method for producing the electronic component mounting substrate.SOLUTION: There is provided an electronic component coating sheet for use in TOM molding or the like for forming a coating layer 3 of an electronic component mounting substrate 10 that includes a substrate 1, an electronic component 2, and the coating layer 3. The coating sheet has (i) a breaking elongation of 800-2,000% as measured at a tension speed of 50 mm / min at Tg to Tg+40°C, (ii) a breaking elongation of 500-1,500% as measured at a tension speed of 1,000 mm / min at Tg to Tg+40°C, and (iii) a piercing strength of 10-200 N / mm per unit film thickness at 23°C as measured by a piercing test conforming to JIS Z1707.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an electronic component mounting substrate and a manufacturing method thereof, and also to an electronic component covering sheet and a laminate sheet. [Background technology]

[0002] Electronic components such as IC chips mounted on a substrate are protected by a coating layer, which increases the substrate's resistance to bending and protects it from physical impacts and temperature changes.

[0003] The formation of the covering layer is being replaced by a heat-meltable electronic component covering sheet instead of the conventional conformal coating. For example, Patent Document 1 discloses a method for sealing an electronic component in which an electronic component mounted on a substrate is covered with a sheet made of a thermosetting resin composition and then cured by heating. Patent Document 2 discloses a method for manufacturing a sealing film having an insulating layer and an electromagnetic wave shielding layer. The sealing film has an elongation rate of 150 to 3500% at the softening point, and is provided with concaves and convexes corresponding to the concaves and convexes formed on the electronic component mounting substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-054363 A [Patent Document 2] JP 2019-021757 A Summary of the Invention [Problem to be solved by the invention]

[0005] As a method for attaching a film to a three-dimensional shape, for example, the Three Dimension Overlay Method (TOM) is known. The TOM method can cover the uneven shape and can provide various functions such as decorativeness and insulation, so it is used for decorative applications such as interior parts of automobiles. Since the TOM method is suitable for covering three-dimensional shapes, it is also promising as a covering layer for electronic component mounting substrates. However, electronic components are small in size and electronic components with different shapes and heights are densely mounted, so covering defects such as wrinkles and breaks in the covering layer are likely to occur. Covering defects not only cause poor appearance, but also lead to quality deterioration and performance deterioration. In the case of a covering layer that requires insulation, it can cause insulation defects in electronic component mounting substrates. In addition, in the case of a covering layer that requires electromagnetic wave shielding, the shielding properties can be reduced. These problems can become more serious due to the reduction in weight, thickness, and size. In addition, if the positional deviation of the covering layer can be prevented, it becomes possible to cover only the areas that need to be covered. Furthermore, it is expected that versatility will be significantly improved. Although the above has been described as a problem with TOM molding, similar issues can arise in vacuum molding, pressure molding, vacuum and pressure molding, press molding, injection molding, and the like.

[0006] The present disclosure has been made in consideration of the above problems, and an object of the present disclosure is to provide an electronic component covering sheet, a laminated sheet, and an electronic component mounting substrate having the covering layer, which can form a high-quality covering layer that can improve wrinkles and breakage and suppress misalignment of the covering position, and a method for manufacturing the same. [Means for solving the problem]

[0007] As a result of extensive investigations, the present inventors have found that the problems of the present disclosure can be solved in the following aspect, and have thus completed the present disclosure. [1]: An electronic component covering sheet for forming a covering layer of an electronic component mounting substrate, the electronic component mounting layer comprising: a substrate; an electronic component mounted on the substrate; and a covering layer covering the electronic component and at least a part of the substrate, (i) the electronic component covering sheet is placed in an atmosphere of from room temperature to Tg to Tg+40° C. of the electronic component covering sheet, and the breaking elongation measured at the temperature and at a tensile speed of 50 mm / min is 800% to 2000%, (ii) the electronic component covering sheet is placed in an atmosphere of from room temperature to Tg to Tg+40° C. of the electronic component covering sheet, and has a breaking elongation of 500 to 1500% when measured at a tensile speed of 1000 mm / min at the temperature; and (iii) The electronic part covering sheet has a puncture strength per unit thickness at 23° C. of 10 to 200 N / mm as measured in a puncture test in accordance with JIS Z1707. [2]: The electronic component covering sheet is placed in an atmosphere of room temperature to Tg to Tg+40°C of the electronic component covering sheet, and the Young's modulus E is measured at the temperature and a tensile speed of 50 mm / min. 50 and, The electronic component covering sheet is placed in an atmosphere of room temperature to Tg to Tg+40° C. of the electronic component covering sheet, and the Young's modulus E is measured at the temperature and a tensile speed of 1000 mm / min. 1000 E 1000 / E 50 The electronic part covering sheet according to [1], wherein the refractive index is 0.8 or more. [3]: A composition comprising a thermosetting resin and a curable compound, the curable compound being a trifunctional or higher curable compound having a N atom (c1); and The electronic part covering sheet according to [1] or [2], comprising a bifunctional curable compound (c2) having no N atom. [4]: A laminate sheet comprising a support layer and the electronic part covering sheet according to any one of [1] to [3]. [5]: The laminate sheet according to [4], having a release layer between the support layer and the electronic component covering sheet. [6]: The glass transition temperature Tg2 of the support layer and the glass transition temperature Tg1 of the electronic component covering sheet are |Tg2-Tg1|≦20℃ The laminate sheet according to [4] or [5], wherein: [7]: An electronic component mounting substrate comprising a substrate, an electronic component mounted on the substrate, and a covering layer covering the electronic component and at least a portion of the substrate, The covering layer is an electronic component mounting substrate, which is a layer formed using the electronic component covering sheet according to any one of [1] to [3]. [8]: A method for manufacturing an electronic component-mounted substrate comprising a substrate, an electronic component mounted on the substrate, and a covering layer covering the electronic component and at least a portion of the substrate, comprising: A method for producing an electronic component mounting substrate, comprising a covering step of forming the covering layer using the electronic component covering sheet according to any one of [1] to [3], the covering step being carried out by any one of a TOM method, a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a press forming method, and an injection molding method. [9]: A method for manufacturing an electronic component-mounted substrate comprising a substrate, electronic components mounted on the substrate, and a coating layer that covers the electronic components and at least a portion of the substrate, the method comprising: a coating step of forming the coating layer using a laminate sheet according to any one of [4] to [6]; and a step of removing layers of the laminate sheet other than the coating layer after the coating step, the method being performed by any one of a TOM method, a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a press molding method, and an injection molding method. Effect of the Invention

[0008] The present disclosure has the excellent effect of providing an electronic component covering sheet, a laminated sheet, and an electronic component mounting substrate having the covering layer, which can form a high-quality covering layer that can improve wrinkles and breakage and suppress misalignment of the covering position, and a method for manufacturing the same. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of an electronic component mounting board according to a first embodiment. [Diagram 2] FIG. 1 is a schematic cross-sectional view showing an example of an electronic component covering sheet according to a first embodiment. [Diagram 3]3A to 3C are schematic cross-sectional views showing an example of a manufacturing process of the first embodiment. [Figure 4] 3A to 3C are schematic cross-sectional views showing an example of a manufacturing process of the first embodiment. [Diagram 5] 3A to 3C are schematic cross-sectional views showing an example of a manufacturing process of the first embodiment. [Figure 6] FIG. 11 is a schematic cross-sectional view showing an example of an electronic component covering sheet according to a second embodiment. [Figure 7] 11A to 11C are schematic cross-sectional views showing an example of a laminate sheet according to a third embodiment and a manufacturing process thereof. [Figure 8] FIG. 11 is a schematic cross-sectional view showing an example of a laminate sheet according to a fourth embodiment. [Figure 9] 9 is a cross-sectional view taken along line IX-IX of FIG. 8 . [Figure 10] FIG. 13 is a schematic cross-sectional view showing an example of an electronic component mounting board according to a fifth embodiment. [Figure 11] FIG. 13 is a schematic top view showing an example of a laminate sheet according to a fifth embodiment. [Figure 12] FIG. 2 is a schematic side view showing an example of a substrate on which an electronic component according to an embodiment is mounted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An example of an embodiment to which the present disclosure is applied will be described below. Each embodiment can be combined in any way. The size and ratio of each member in the following figures are for convenience of explanation and are not limited thereto. In addition, in the present specification, the description of "any number A to any number B" includes the number A as the lower limit and the number B as the upper limit in the range. In addition, the sheet and the film are synonymous. Furthermore, the numerical values ​​specified in this specification are values ​​obtained by the method disclosed in the embodiment or example. In addition, each component may be used alone or in combination of two or more types, unless otherwise specified.

[0011] 1. First embodiment 1-1. Electronic component mounting board An example of a schematic cross-sectional view of an electronic component mounting board according to a first embodiment of the present disclosure is shown in Fig. 1. As shown in the figure, an electronic component mounting board 10 of the first embodiment includes a substrate 1, an electronic component 2 mounted on the substrate 1, and a covering layer 3.

[0012] The substrate 1 may be any substrate capable of mounting the electronic component 2 and enduring the molding process for each application. It may be selected arbitrarily. The substrate 1 may be provided with an electrode / wiring pattern, vias (not shown), etc., as desired. The substrate may be rigid or flexible. Examples of the substrate include a work board having a conductive pattern made of copper foil or the like formed on its surface and / or inside, a mounting module substrate, a printed wiring board, and a build-up substrate formed by a build-up method or the like.

[0013] The electronic component 2 is mounted on the main surface of the substrate 1. When multiple electronic components are mounted, the shapes and heights of the electronic components may be the same or different. Specific examples of the electronic components 2 include IC chips, multilayer ceramic chip capacitors (MLCCs), inductors, and thermistors.

[0014] The covering layer 3 covers the upper surface and the side surface of the electronic component 2, and further covers the entire exposed surface of one main surface of the substrate 1. In other words, the covering layer 3 is provided so as to cover the step portion (uneven portion) formed by mounting the electronic component 2, and the covering layer 3 is provided on the entire exposed surface of one main surface of the substrate 1. The covering layer 3 is formed by using the electronic component covering sheet of the present disclosure (hereinafter, also referred to as the present covering sheet). Although there is no limitation on the method for forming the covering layer 3 from the present covering sheet, any one of the three-dimensional surface covering methods TOM (Three Dimension Overlay Method) forming method, vacuum forming method, pressure forming method, vacuum pressure forming method, press forming method, and injection molding method is preferable. Among these, the present covering sheet is particularly suitable for TOM forming.

[0015] The coating layer 3 is formed of a single layer or multiple layers. The coating layer can be given functions according to needs. For example, it can be composed of an insulating layer, a conductive layer, a thermally conductive layer, a waterproof layer, a shielding layer, a colored layer, a flame retardant layer, a hard coat layer, a decorative layer, etc. Examples include a single or multiple insulating layer, a single or multiple conductive layer, and a coating layer of an insulating layer / conductive layer. In addition to protecting the exposed surface of the main surface of the substrate 1 with the coating layer 3, the side surface of the substrate 1 may also be protected with the coating layer 3 as shown in FIG. 1.

[0016] 1, an example in which the electronic component 2 is mounted on one main surface of the substrate 1 has been described, but electronic components may be mounted on both main surfaces of the substrate, and both main surfaces of the substrate may be covered with a covering layer. Also, a covering layer may be provided not on the entire exposed surface of the main surface of the substrate 1, but only on a part of it, as in the case of an electronic component mounting substrate of a fifth embodiment described later.

[0017] 1-2. Electronic component covering sheet As described above, the electronic component covering sheet (present covering sheet) of the present disclosure is a sheet for forming a covering layer of an electronic component mounting board. The present covering sheet can physically protect electronic components and can impart specific functions. Suitable examples of the present covering sheet include an insulating sheet having insulation properties, a conductive sheet functioning as an electromagnetic wave shielding layer, a heat conductive sheet that dissipates heat from electronic components, a shielding sheet that prevents electronic components from being seen or blocks light, a moisture-proof sheet that protects electronic components from moisture, a decorated sheet, a flame-retardant sheet that has been given flame retardancy, a protective sheet that has been given hard coat properties, and a sheet having any combination of these functions. Suitable examples of covering sheets having multiple functions include a covering sheet that combines insulation and thermal conductivity, a covering sheet that combines insulation and shielding properties, a covering sheet that combines conductivity and shielding properties, and a covering sheet that combines insulation and moisture-proof properties.

[0018] The coating sheet may be a single layer or a multi-layer. In the case of a multi-layer, a plurality of layers having the same function may be laminated, or layers having different functions may be laminated. For example, a coating sheet having a laminated structure of an insulating layer / conductive layer, an insulating layer / hard coat layer, an insulating layer / waterproof layer, or a thermally conductive layer / insulating layer can be exemplified.

[0019] FIG. 2 is a schematic cross-sectional view of an example of the electronic component covering sheet according to the first embodiment. As shown in the figure, the covering sheet 4 of the first embodiment has a laminated structure of an insulating layer 31 and a conductive layer 32. The insulating layer 31 is disposed on the electronic component 2 side to insulate and protect the electronic component, and the conductive layer 32 disposed thereon can provide, for example, electromagnetic wave shielding properties. The conductive layer 32 and the ground (not shown) of the substrate 1 may be electrically connected by a pin (not shown) or the like. Instead of the above embodiment, the conductive layer 32 may be disposed on the electronic component 2 side, and the insulating layer 31 may be disposed thereon.

[0020] The present covering sheet is a precursor product of the covering layer, and satisfies the following (i) to (iii). In the case of a multi-layer structure, each layer does not need to satisfy (i) to (iii), and it is sufficient that the covering sheet satisfies (i) to (iii). (i) The electronic part covering sheet is placed in an atmosphere of from room temperature to Tg to Tg+40° C., and the breaking elongation is 800 to 2000% when measured at the temperature and at a tensile speed of 50 mm / min. (ii) When the electronic part covering sheet is placed in an atmosphere of from room temperature to Tg to Tg+40° C. and measured at that temperature at a tensile speed of 1000 mm / min, the breaking elongation is 500 to 1500%. (iii) The electronic part covering sheet has a puncture strength per unit film thickness at 23° C. of 10 to 200 N / mm, as measured in a puncture test in accordance with JIS Z1707. The Tg in the present disclosure is a value obtained by the method of this embodiment. Moreover, "Tg to Tg+40°C" is a condition for indicating the characteristics of the electronic component covering sheet, and does not limit the temperature when forming the covering layer to this range. Moreover, the numerical values ​​of (i) to (iii) above are values ​​obtained by carrying out the method and conditions described in the embodiment described later.

[0021] The breaking elongation refers to the permanent elongation value after the covering sheet breaks when the covering sheet is subjected to a tensile test, which was performed according to the method specified in JIS K7161:1994.

[0022] In the present covering sheet, by setting the breaking elongation of the above (i) to 800% or more and the breaking elongation of the above (ii) to 500% or more, the covering sheet can be made to have good elongation and the covering layer can be prevented from breaking. On the other hand, by setting the breaking elongation of the above (i) to 2000% or less and the breaking elongation of the above (ii) to 1500% or less, the occurrence of wrinkles can be prevented. The control for satisfying the above (i) and (ii) in the present covering sheet can be adjusted by the type of the curable compound in the composition forming the present covering sheet. Specifically, it can be adjusted by the number of functional groups and equivalent weight of the curable compound. It can also be adjusted by the content of the curable compound in the composition. It can also be adjusted by the type, amount and particle size of the filler. It can also be adjusted by a flexibility adjuster that does not contribute to crosslinking, such as a plasticizer, an inert resin or an oligomer that is not reactive by itself.

[0023] The puncture strength is a value obtained in a puncture test conforming to JIS Z1707 (23°C), specifically, the strength at which a stainless steel rod (diameter 1 mm) is dropped perpendicularly onto a covering sheet and the covering sheet breaks. The puncture strength per unit thickness is obtained by dividing the puncture strength by the thickness of the covering sheet for electronic components. When the puncture strength per unit thickness satisfies the above (iii), breakage of the covering sheet at the edges of electronic components can be effectively prevented, and a covering sheet with excellent quality can be provided.

[0024] The control for satisfying the above (iii) can be easily adjusted by the crosslink density of the present coating layer. A method of adjusting the number of functional groups and equivalent weight of the curable compound in the composition for forming the present coating sheet is suitable. The curable compound is preferably bifunctional or more, and more preferably contains a trifunctional or tetrafunctional curable compound. It can also be adjusted by the content of the curable compound in the composition. It can also be adjusted by the type, amount and particle size of the filler. It can also be adjusted by the type of flexibility regulator that does not contribute to crosslinking, such as a plasticizer, an inert resin or an oligomer that is not reactive by itself.

[0025] By satisfying the above (i) and (ii), it is possible to effectively suppress the occurrence of wrinkles in the covering layer during the decompression process such as TOM molding. Furthermore, by satisfying the above (i) and (ii) and further satisfying (iii), it is possible to effectively prevent the sheet from breaking at the edge when heat and stress are applied to the covering sheet or when the electronic component mounting substrate is subjected to an impact. It is also possible to suppress deviation of the lamination position. As a result, it is possible to significantly improve the quality of the covering sheet. In addition, it is possible to effectively improve appearance defects. Therefore, according to the present covering sheet, it is possible to provide an electronic component mounting substrate having a covering layer of excellent quality, including a substrate mounted with electronic components of different heights.

[0026] The breaking elongation of the above (i) is more preferably 900 to 1700%, and even more preferably 1000 to 1500%, from the viewpoint of preventing the covering layer from breaking and wrinkling. By making it 900% or more, the strength of the covering sheet can be further increased, and breaking of the covering layer can be more effectively prevented. The breaking elongation of the above (ii) is more preferably 650 to 1400%, and even more preferably 800 to 1300%, from the viewpoint of preventing the covering layer from breaking and wrinkling. The puncture strength per unit thickness of the above (iii) is more preferably 50 to 170 N / mm, and even more preferably 70 to 150 N / mm, from the viewpoint of preventing the covering layer from breaking.

[0027] When the covering sheet contains a thermosetting resin, the covering sheet becomes a covering layer through a curing process by heating the covering sheet for electronic parts. The covering sheet for electronic parts may have a release sheet on one or both sides for surface protection.

[0028] In addition, from the viewpoint of preventing the coating layer from breaking and improving its ability to conform to the adherend, the coating sheet is placed at room temperature in an atmosphere of Tg to Tg+40°C and the Young's modulus E is measured at that temperature at a tensile speed of 50 mm / min. 50 The Young's modulus E of the present covering sheet at room temperature is preferably 1 to 18 GPa, more preferably 3 to 15 GPa, and even more preferably 6 to 12 GPa. The Young's modulus E of the present covering sheet at room temperature is measured at a tensile speed of 1000 mm / min at the same temperature by placing the present covering sheet in an atmosphere at Tg to Tg+40°C. 1000The Young's modulus during high speed tension is preferably from 2 to 20 GPa, more preferably from 4 to 18 GPa, and even more preferably from 6 to 15 GPa. It is believed that by setting the Young's modulus during high speed tension within the above range, the sheet does not bend during TOM molding or the like, and wrinkles can be suppressed.

[0029] The Young's modulus can be adjusted to the above range, for example, by adjusting the crosslink density. Specifically, it can be adjusted by adjusting the number of functional groups and equivalent weight of the curable compound in the composition for forming the present covering sheet. It can also be adjusted by the content of the curable compound in the composition. It can also be adjusted by the type, amount, and particle size of the filler. It can also be adjusted by the type of flexibility regulator that does not contribute to crosslinking, such as a plasticizer, an inert resin that is not reactive by itself, or an oligomer.

[0030] Young's Modulus E 1000 and Young's modulus E 50 Ratio of E 1000 / E 50 The ratio E is preferably 0.8 or more. 1000 / E 50 The ratio E is preferably 0.9 or more. 1000 / E 50 The upper limit of the ratio E is preferably 1.4 or less, and more preferably 1.3 or less. 1000 / E 50 By setting the thickness within the above range, breakage of the sheet at uneven portions, particularly at edges, of electronic components can be prevented, and defects in appearance can be more effectively prevented.

[0031] From the viewpoint of preventing the covering layer from breaking and wrinkling, the Tg of the covering sheet is preferably in the range of 0 to 80° C., more preferably 15 to 45° C. When the covering sheet is multi-layered, it is preferable that the Tg of each layer is in the above range. When the covering sheet is multi-layered, the Tg of the layer with the highest Tg is used as the reference.

[0032] The thickness of the covering sheet can be appropriately designed depending on the application. For applications requiring a thinner sheet, the thickness of the covering sheet covering the upper and side surfaces of the electronic component is preferably in the range of 10 to 1000 μm, more preferably 15 to 500 μm, and even more preferably 20 to 250 μm.

[0033] When this covering sheet is used as an insulating layer, the surface resistance is 1.0×10 7 It is preferable that the resistance is Ω / □ or more, and 1.0×10 8 More preferably, it is 1.0×10 9 It is more preferable that the surface resistance of the conductive layer is 1.0×10 5 It is preferable that the resistance is Ω / □ or less, and 1.0×10 3 It is more preferable that the resistance is 1.0×10 2 It is more preferable that the resistance is Ω / □ or less.

[0034] The covering sheet includes a binder component. The binder component is a component that serves as the base of the covering layer. Examples of resins used in the binder component include thermosetting resins, photocurable resins, and mixtures thereof. Curable compounds that crosslink with these resins are also included in the binder component. As the thermosetting resin, in addition to self-crosslinking thermosetting resins, thermosetting resins that can react with curable compounds are suitable. These may be combined. As the binder resin, a combination of a thermosetting resin and a curable compound is suitable. When a curable compound is used, a thermosetting resin having a reactive functional group that can react with the curable compound is preferred. The binder resin can be used alone or in combination of two or more types.

[0035] The thermosetting resin has a curable compound or a reactive functional group that self-crosslinks, such as a phenolic hydroxyl group, an acid anhydride group, a methoxymethyl group, a carboxyl group, an amino group, an epoxy group, an oxetanyl group, an oxazoline group, an oxazine group, an aziridine group, a thiol group, an isocyanate group, a blocked isocyanate group, a blocked carboxyl group, a silanol group, etc.

[0036] Examples of the thermosetting resin include polyurethane resin, polyurethane urea resin, phenoxy resin, acrylic resin, polyester resin, polyamide resin, epoxy resin, polystyrene resin, polycarbonate resin, polyamideimide resin, polyesteramide resin, polyetherester resin, alkyd resin, polyimide resin, benzoxazine resin, amino resin, polylactic acid resin, oxazoline resin, silicone resin, and fluororesin. Among these, epoxy resin, polyurethane resin, polyurethane urea resin, polycarbonate resin, phenoxy resin, polyimide resin, polyamideimide resin, and polyamide resin are preferable from the viewpoint of improving high temperature resistance.

[0037] From the viewpoint of improving edge coverage, the acid value of the thermosetting resin is preferably from 3 to 30 mgKOH / g, more preferably from 4 to 20 mgKOH / g, and further preferably from 5 to 10 mgKOH / g.

[0038] The curable compound has a functional group capable of reacting with the thermosetting resin. It is preferable that the functional group is a plurality of functional groups. Examples of the curable compound include epoxy compounds, isocyanate compounds, polycarbodiimide compounds, aziridine compounds, acid anhydride group-containing compounds, dicyandiamide compounds, amine compounds such as aromatic diamine compounds, phenolic compounds such as phenol novolac resins, and organometallic compounds. The curable compound may be a resin or a low molecular weight compound. When a resin is used as the curable compound, the thermosetting resin and the curable compound are distinguished by the fact that the one with a higher content is the thermosetting resin and the one with a lower content is the curable compound. The curable compound may be used alone or in combination of two or more kinds.

[0039] From the viewpoint of effectively suppressing wrinkles and breakage of the covering layer, a combination of a trifunctional or higher curable compound (c1) having an N atom (hereinafter also referred to as curable compound (c1)) and a bifunctional curable compound (c2) having no N atom in the functional group (hereinafter also referred to as curable compound (c2)) is suitable. By using the curable compound (c1), the curing reaction before the curing process can be promoted to some extent, and breakage of the covering sheet during elongation in TOM molding or the like can be effectively prevented. On the other hand, by using the curable compound (c2), the crosslinking density can be suppressed and crosslinking can be allowed to proceed slowly, so that the breaking elongation during TOM molding or the like can be maintained at a good level.

[0040] Suitable examples of the curable compound (c1) include trifunctional or higher glycidylamines and trifunctional or higher aziridines, and suitable examples of the curable compound (c2) include bifunctional epoxy compounds.

[0041] Examples of trifunctional or higher functional glycidylamines include N-glycidyl compounds obtained by reacting aromatic amines (such as aniline and toluidine) having 6 to 20 carbon atoms and 2 to 4 active hydrogen atoms with epichlorohydrin. Specifically, tetraglycidylamine phenylmethane, triglycidyl-p-aminophenol, and tetraglycidyl-m-xylylenediamine are also suitable. Examples of commercially available products include Sumiepoxy ELM-100, ELM-120 (manufactured by Sumitomo Chemical Co., Ltd.), MY721 (manufactured by Ciba Specialty Chemicals Co., Ltd.), TETRAD-X and TETRAD-C (trade names) manufactured by Mitsubishi Gas Chemical Co., Ltd., and GAN (trade name) manufactured by Nippon Kayaku Co., Ltd.

[0042] Examples of the trifunctional or higher functional aziridines include trifunctional aziridines such as trimethylolpropane tris(3-(2-methyl-1-aziridyl)propionic acid) ester, trimethylolpropane tris(3-(1-aziridyl)propionic acid) ester, pentaerythritol tris(3-(2-methyl-1-aziridyl)propionic acid) ester, pentaerythritol tris(3-(1-aziridyl)propionic acid) ester, dipentaerythritol tris(3-(1-aziridyl)propionic acid) ester, and sorbitol tris(3-(1-aziridyl)propionic acid) ester;

[0043] Examples of aziridines include tetrafunctional aziridines such as sorbitol tetrakis(3-(1-aziridyl)propionic acid) ester, sorbitol tetrakis(3-(1-aziridyl)propionic acid) ester, and ditrimethylolpropane tetrakis(3-(1-aziridyl)propionic acid) ester; pentafunctional aziridines such as sorbitol pentakis(3-(1-aziridyl)propionic acid) ester and dipentaerythritol pentakis(3-(1-aziridyl)propionic acid) ester; and hexafunctional aziridines such as dipentaerythritol hexakis(3-(1-aziridyl)propionic acid) ester and sorbitol hexakis(3-(1-aziridyl)propionic acid) ester.

[0043] Examples of bifunctional epoxy compounds include bisphenol-based diglycidyl ethers such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol E diglycidyl ether, bisphenol Z diglycidyl ether, bisphenol S diglycidyl ether, bisphenol AD ​​diglycidyl ether, bisphenol acetophenone diglycidyl ether, bisphenol trimethylcyclohexane diglycidyl ether, bisphenol fluorene diglycidyl ether, tetramethyl bisphenol A diglycidyl ether, tetramethyl bisphenol F diglycidyl ether, tetra-t-butyl bisphenol A diglycidyl ether, and tetramethyl bisphenol S diglycidyl ether; biphenol-based diglycidyl ethers such as biphenol diglycidyl ether, tetramethyl biphenol diglycidyl ether, dimethyl biphenol diglycidyl ether, and tetra-t-butyl biphenol diglycidyl ether; hydroquinone diglycidyl ether, dihy Benzene diglycidyl ethers such as dihydroanthracene diglycidyl ether, methylhydroquinone diglycidyl ether, dibutylhydroquinone diglycidyl ether, resorcinol diglycidyl ether, and methylresorcinol diglycidyl ether; aromatic diglycidyl ethers such as dihydroanthrahydroquinone diglycidyl ether, dihydroxydiphenyl ether diglycidyl ether, thiodiphenol diglycidyl ether, and dihydroxynaphthalene diglycidyl ether; Epoxy compounds in which hydrogen has been added to the aromatic ring of diglycidyl ethers selected from the group consisting of bisphenol diglycidyl ethers, biphenol diglycidyl ethers, benzenediol diglycidyl ethers and aromatic diglycidyl ethers; epoxy resins produced from various carboxylic acids such as adipic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, methylhexahydrophthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, biphenyldicarboxylic acid and dimer acid, and epihalohydrin;Examples of the alkylene glycol diglycidyl ether include (poly)alkylene glycol diglycidyl ethers consisting only of a chain structure, such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, 1,5-pentanediol diglycidyl ether, polypentamethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyhexamethylene glycol diglycidyl ether, 1,7-heptanediol diglycidyl ether, polyheptamethylene glycol diglycidyl ether, 1,8-octanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, and 2,2-dimethyl-1,3-propanediol diglycidyl ether; and alkylene glycol diglycidyl ethers having a cyclic structure, such as 1,4-cyclohexanedimethanol diglycidyl ether. Examples of commercially available products include EPICLON 830, 840, 850, 860, 1050, 2050, 3050, 4050, 7050, HM-091, and 101 manufactured by DIC, and Denacol EX-211, 212, 252, 711, and 721 manufactured by Nagase ChemteX.

[0044] In a heat press or the like, the epoxy group of the epoxy compound thermally crosslinks with the carboxyl group or hydroxyl group of the thermosetting resin to obtain a crosslinked structure. As the epoxy compound, an epoxy compound that is liquid at room temperature (25°C) is also suitable. Specific examples include liquid bisphenol-type epoxy resins such as "R140P" (epoxy equivalent 188) manufactured by Mitsui Chemicals, Inc., "DER383" manufactured by Dow Chemical Company, and "Epicoat #807" (epoxy equivalent 170) manufactured by Japan Epoxy Resins.

[0045] The content of the curable compound (c1) is preferably 0.1 to 7 parts by mass, more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the thermosetting resin r. The content of the curable compound (c2) is preferably 1 to 50 parts by mass, more preferably 5 to 30 parts by mass, per 100 parts by mass of the thermosetting resin r. The ratio of the curable compound (c2) / curable compound (c1) is preferably 3 to 150, more preferably 3 to 50. By setting the ratio within the above range, a strong crosslinked structure is formed in the coating layer, and excessive curing of the coating layer is suppressed, and the conformability to the uneven shape can be improved. Furthermore, a coating layer that can effectively suppress wrinkles and breakage in the TOM molding method or the like can be formed.

[0046] The covering sheet may further contain a filler. When insulation is required, an insulating filler is used, when conductivity is required, a conductive filler is used, and when electromagnetic wave absorption is required, an electromagnetic wave absorbing filler is used. The shape of the filler can be appropriately selected. For example, flake-shaped, needle-shaped, spherical, dendritic, and fibrous fillers can be used. Fillers of different shapes can be used in combination. A suitable example is a combination of a flake-shaped filler and a dendritic filler.

[0047] The average particle size D50 of the filler is preferably 1 to 100 μm, more preferably 2 to 80 μm, even more preferably 3 to 50 μm, and particularly preferably 5 to 20 μm. Similarly, the average particle size D50 of the dendritic conductive filler is preferably in the range of 2 to 100 μm, more preferably 2 to 80 μm, even more preferably 3 to 50 μm, and particularly preferably 5 to 20 μm.

[0048] From the viewpoint of preventing the covering layer from breaking and wrinkling, the filler content is preferably 1 to 50 mass% and more preferably 1.5 to 35 mass% relative to 100 mass% of the covering sheet. In the case of a multi-layered sheet, the total of all layers (where n is an integer of 2 or more) (filler content of n layers×film thickness of n layers / (film thickness of entire covering layer)) is preferably 1 to 50 mass%, more preferably 1.5 to 35 mass%.

[0049] Examples of the insulating filler include non-metallic inorganic fillers such as silica, alumina, boron nitride, aluminum nitride, magnesium silicon nitride, silicon carbide, titania, glass, ceramics, etc. The insulating filler may be used alone or in combination of two or more kinds.

[0050] Examples of the conductive filler include metal fillers, conductive ceramic fillers, and mixtures thereof. Examples of the metal filler include metal powders such as gold, silver, copper, and nickel, alloy powders such as solder, and core-shell fillers such as silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. From the viewpoint of obtaining excellent conductive properties, conductive fillers containing silver are preferred. From the viewpoint of cost, silver-coated copper powder is particularly preferred.

[0051] Examples of the electromagnetic wave absorbing filler include iron alloys such as iron, Fe-Ni alloy, Fe-Co alloy, Fe-Cr alloy, Fe-Si alloy, Fe-Al alloy, Fe-Cr-Si alloy, Fe-Cr-Al alloy, and Fe-Si-Al alloy, ferrite-based substances such as Mg-Zn ferrite, Mn-Zn ferrite, Mn-Mg ferrite, Cu-Zn ferrite, Mg-Mn-Sr ferrite, and Ni-Zn ferrite, and carbon fillers. Examples of the carbon filler include acetylene black, ketjen black, furnace black, carbon black, carbon fiber, fillers made of carbon nanotubes, graphene fillers, graphite fillers, and carbon nanowalls.

[0052] The covering sheet may contain a flexibility regulator. The flexibility regulator can reduce wrinkling and tearing of the covering sheet during molding. Examples of the flexibility regulator include a plasticizer and an inert thermoplastic resin.

[0053] Examples of the plasticizer include fatty acid esters, phthalic acid esters, aromatic polyvalent carboxylic acid esters, and polyesters. Examples of fatty acid esters include trioctyl trimellitate (TOTM), manufactured by Mitsubishi Gas Chemical Trading Co., Ltd., butyl stearate, Unistar M-9676, Unistar M-2222SL, Unistar H-476, Unistar H-476D, Panasate 800B, Panasate 875, Panasate 810 (all manufactured by NOF Corp.), DBA, DIBA, DBS, DOA, DINA, DIDA, DOS, BXA, DOZ, and DESU (all manufactured by Daihachi Chemical Co., Ltd.). Examples of phthalic acid esters include DMP, DEP, DBP, #10, BBP, DOP, DINP, and DIDP (hereinafter, manufactured by Daihachi Chemical Co., Ltd.), PL-200, and DOIP (all manufactured by C.G. Ester Co., Ltd.), and Sanso Cizer DUP (manufactured by New Japan Chemical Co., Ltd.). Examples of aromatic polycarboxylic acid esters include TOTM (manufactured by Daihachi Chemical Industry Co., Ltd.), Monocizer W-705 (manufactured by Daihachi Chemical Industry Co., Ltd.), UL-80, and UL-100 (manufactured by ADEKA Corporation). Examples of polyesters include Polysizer TD-1720, Polysizer S-2002, Polysizer S-2010 (all manufactured by DIC Corporation), and BAA-15 (manufactured by Daihachi Chemical Industry Co., Ltd.). Among these, DMP, DEP, DBP, DOP, DINP, DIDP, and TOTM are more preferable. The plasticizers may be used alone or in combination of two or more.

[0054] Examples of the inert thermoplastic resin include polyolefin resins, vinyl resins, styrene-acrylic resins, diene resins, terpene resins, petroleum resins, cellulose resins, polyamide resins, polyurethane resins, polyester resins, polycarbonate resins, polyimide resins, liquid crystal polymers, and fluororesins. Although not particularly limited, polyamide resins, polyurethane resins, polyester resins, polycarbonate resins, polyimide resins, liquid crystal polymers, and fluororesins are more preferable from the viewpoint of heat resistance.

[0055] Furthermore, the coating sheet may contain a tackifier resin to improve adhesion to the substrate. The tackifier resin is a component that supplementarily improves adhesive strength, has a weight-average molecular weight of less than 5,000, and is distinguished from the thermoplastic resin and binder resin. Examples of the tackifier resin include rosin resin, terpene resin, alicyclic petroleum resin, and aromatic petroleum resin.

[0056] The covering sheet may further contain a colorant, a flame retardant, a lubricant, an antiblocking agent, etc. Examples of the flame retardant include a halogen-containing flame retardant, a phosphorus-containing flame retardant, a nitrogen-containing flame retardant, an inorganic flame retardant, etc. Examples of the lubricant include a fatty acid ester, a hydrocarbon resin, paraffin, a higher fatty acid, a fatty acid amide, an aliphatic alcohol, a metal soap, a modified silicone, etc. Examples of the antiblocking agent include calcium carbonate, silica, polymethylsilsesquioxane, and aluminum silicate.

[0057] In the example of FIG. 2, an example of a covering sheet consisting of a multi-layer of insulating layer 31 / conductive layer 32 is given, but as described above, it may be a single-layer covering sheet or a covering sheet consisting of multiple layers with the same function. In addition, a second layer may be patterned at an arbitrary position of the first layer. For example, by using a covering sheet in which an insulating layer 31 is patterned at an arbitrary position of the conductive layer 32, the conductive layer 32 can be formed on the entire exposed surface of one main surface of the substrate 1, and a covering layer having an insulating layer 31 can be formed at a location requiring insulation protection. According to this covering sheet, the displacement of the covering layer can be effectively prevented, so that the design freedom of the covering sheet can be significantly increased.

[0058] 1-3. Manufacturing method of electronic component covering sheet The method for producing the present covering sheet is not particularly limited, but for example, a method of applying a composition in which the material such as the binder resin forming the covering layer is dissolved in a solvent or the like to a release sheet can be mentioned. Examples of the application method include gravure coating, kiss coating, die coating, lip coating, comma coating, blade coating, roll coating, knife coating, spray coating, bar coating, spin coating, dip coating, and various printing methods. In the case of multiple layers, known methods such as lamination and lamination via an easy adhesive can be applied.

[0059] 1-4. Uses of electronic component covering sheets The covering sheet of the present invention is particularly suitable for covering electronic component mounting substrates, but may also be used to cover other objects to be covered. Electronic component mounting substrates using the covering sheet of the present invention are preferably provided in electronic devices such as liquid crystal displays, touch panels, notebook PCs, mobile phones, smartphones, tablet terminals, etc.

[0060] 1-5. Manufacturing method for electronic component mounting board An example of a TOM molding method will be described as a method for manufacturing an electronic component mounting substrate using the present covering sheet. However, the method for manufacturing the present electronic component mounting substrate is not limited to the following. The present covering sheet may be used to form a covering layer by a method other than the TOM molding method (e.g., vacuum forming, pressure forming, vacuum pressure forming, press molding, injection molding). For example, the covering layer can be formed from the present covering sheet by the method described in Japanese Patent No. 7193031.

[0061] The method for producing the electronic component mounting board includes a step of mounting one or more electronic components on a board (step A), a step of preparing an electronic component covering sheet cut to a predetermined size (step B), and a covering step of forming a covering layer using the covering sheet or the laminated sheet in which the covering sheet is laminated (step C), thereby obtaining an electronic component mounting board covered and protected by a covering layer formed from the electronic component covering sheet of the present disclosure. Step C will be described below with reference to the schematic manufacturing process diagrams of Figs. 3 to 5.

[0062] First, the substrate 1 on which the electronic components 2 are mounted is placed on the stage 5 in the lower space 21 in the box 20 having the lower space 21 and the upper space 22. Next, the cover sheet 4 is placed on the partition plate 6 so as to separate the upper space 22 from the lower space 21 (see FIG. 3). Then, the inside of the box 20 is made into a vacuum state, and the cover sheet 4 is heated by the heat source 7 to around the Tg of the cover sheet 4 to soften it. Around the Tg is, for example, in the range of Tg ±20°C. Note that, when the cover sheet 4 is a multi-layered sheet, the Tg of the layer with the highest Tg is used as the reference. Note that as long as the cover sheet 4 can be fixed, a fixing jig for sandwiching the sheet may be used instead of the partition plate.

[0063] As the temperature of the covering sheet 4 approaches the temperature around the Tg due to heating by the heating source 7, the covering sheet 4 loses flatness and undulation appears (see FIG. 4). When heating is continued, the undulation of the covering sheet 4 is reduced and the covering sheet 4 begins to bend around the center due to its own weight (see FIG. 5). By heating the covering sheet 4 to this state, it is possible to effectively prevent wrinkles from occurring in the covering layer and improve quality. In addition, in order to improve the adhesion of the covering layer to the substrate 1 and the electronic components 2, it is preferable to heat the stage 5 on which the substrate 1 on which the electronic components 2 are mounted is placed. Heating has the effect of improving production efficiency during continuous production. The temperature of the stage 5 during heating is, for example, 50 to 120° C. From the viewpoint of improving continuous productivity, it is preferable that the temperature of the stage 5 during heating is within the range of Tg±20° C.

[0064] If necessary, the stage 5 installed in the lower space 21 is moved upward to bring a part of the covering sheet 4 into contact with or close to the upper surface of the electronic component 2. The surface of the covering sheet 4 is then pressurized from the upper space 22 by air or compressed air. The covering sheet 4 then conforms to the uneven surface of the substrate 1 on which the electronic component 2 is mounted. Next, the excess covering sheet is removed. If a thermosetting resin is used as the binder resin, a heat curing process is performed, and if a photocuring resin is used, a photocuring process is performed. Through these steps, an electronic component mounting substrate 10 having a covering layer 3 as shown in FIG. 1 is obtained.

[0065] According to the above method, the covering sheet can be cut to fit the covering area, and a covering layer can be formed on a substrate on which electronic components are mounted in a general purpose manner regardless of the shape, arrangement, etc. of the electronic components. In addition, since the covering sheet is applied to the entire surface to form a covering layer, and then the excess covering layer is cut off, there is an advantage in that precise alignment between the covering sheet and the substrate on which electronic components are mounted is not required.

[0066] By satisfying the above (i) to (iii), the present covering sheet can form a high-quality covering layer even on electronic components that are made lighter, thinner, and smaller. By using the TOM method, the present covering sheet can be heated and softened by applying pressure difference to conform to a three-dimensional uneven shape, thereby significantly improving productivity.

[0067] 2. Second embodiment An electronic component covering sheet according to a second embodiment will be described. The electronic component covering sheet according to the second embodiment differs from the first embodiment in terms of layer structure as described later, but the basic structure and manufacturing method are the same as those of the first embodiment. In the following figures, the same elements and members as those described above are appropriately designated by the same reference numerals.

[0068] 6 is a schematic cross-sectional view of an example of the electronic component covering sheet according to the second embodiment. The electronic component covering sheet 4a has a first layer 41, a second layer 42, and a third layer 43, all of which are insulating layers, laminated in this order. The first layer 41, the second layer 42, and the third layer 43 may each independently have the same function or different functions. The preferred components, amounts, and properties of the first, second, and third layers are the same as those of the first embodiment.

[0069] The first layer 41, which is disposed so as to face the electronic component, is preferably designed to reduce warpage and improve embedding properties. The second layer 42 is preferably designed to improve conformability to the three-dimensional shape of the electronic component in TOM molding and to reduce warpage. For this reason, it is preferable that the curable compound of the first layer and the second layer contains a liquid epoxy compound.

[0070] A liquid epoxy compound refers to an epoxy compound that is liquid at 25° C. Suitable examples include jER (registered trademark (omitted below)) YL980, jERYL983U, jER152, jER630, jERYX8000 (all trade names, manufactured by Mitsubishi Chemical Corporation), EPICLON (registered trademark), and HP-4032 (all trade names, manufactured by DIC Corporation). The liquid epoxy compounds may be used alone or in combination of two or more kinds.

[0071] The third layer 43 is preferably designed to optimize hardness and enhance durability of the covering sheet, in addition to adjusting the film thickness. It is preferable that the third layer 43 contains a filler to enhance durability.

[0072] According to the second embodiment, the three-layer structure increases the design freedom of each layer, and the coating layer has high functionality. As a result, the adhesion and conformability of the bonding surfaces between the coating sheet 4a and the electronic components 2 and the like are improved, and the coating layer is effectively prevented from wrinkling and from breaking at edges and the like.

[0073] In the second embodiment, an example of a covering sheet having a three-layer structure is given, but the covering sheet may be a single layer or multiple layers (two layers, four or more layers) without departing from the spirit of the present disclosure.

[0074] 3. Third embodiment The manufacturing method for an electronic component mounting substrate in the third embodiment differs from the manufacturing method for the first embodiment in that a laminate sheet having the present covering sheet is used, etc., but the basic structure of the electronic component mounting substrate and the basic manufacturing method are the same as those in the first embodiment.

[0075] 7 is a schematic diagram showing an example of a manufacturing process of an electronic component mounting board according to the third embodiment. In the first embodiment, the cover sheet 4 is placed on the partition plate 6, but in the third embodiment, a laminated sheet 50 is placed on the partition plate 6. The laminated sheet 50 has a support layer 8 and a cover sheet 4 formed on the support layer 8. The size of the cover sheet 4 is set to a size required for forming a cover layer. This method makes it possible to omit the step of cutting off unnecessary parts after forming the cover layer.

[0076] The method for manufacturing the laminated sheet 50 is not limited, but a method of attaching the covering sheet 4 to a desired position on the support layer 8 is simple. A suitable method is, for example, a method of heating the covering sheet 4 to the support layer 8 and temporarily attaching it. The support layer 8 has a role of fixing (in this example, placing and fixing on the partition plate 6) during the manufacturing process and a role of supporting the covering sheet. The support layer can also be called a peeling layer because it is peeled off after the covering layer is formed. The laminated sheet 50 is applied to the substrate 1 on which the electronic components 2 are mounted in the same manner as in the first embodiment to form the covering layer 3, and then the support layer 8 is peeled off to obtain an electronic component-mounted substrate.

[0077] The support layer 8 is not particularly limited as long as it has the above-mentioned functions. Suitable examples include polyvinyl chloride (PVC), polyolefin, and the like. The thickness of the support layer 8 is preferably 5 to 500 μm, and more preferably 10 to 250 μm, from the viewpoint of improving the conformability to the adherend. The Tg of the support layer 8 is preferably 30 to 90° C., and more preferably 40 to 80° C., from the viewpoint of improving the conformability to the adherend. The Tg1 of the cover sheet 4 and the Tg2 of the support layer 8 are |Tg2-Tg1|≦20℃ By setting the relationship in this range, the conformability to the uneven shape of electronic components and the like can be more effectively improved. |Tg2-Tg1|≦10℃ The Tg2 of the support layer can be adjusted by the type of resin and the manufacturing conditions thereof. The temperature inside the box 20 is preferably set within a range of ±20° C. between the higher of Tg1 and Tg2.

[0078] The alignment between the substrate on which the electronic components are mounted and the cover sheet can be performed by any known method without limitation. For example, precise alignment can be performed by aligning a mark on the support layer with a mark on the stage.

[0079] According to the covering sheet of the third embodiment, there is no need to use a covering sheet 4 of a size that can be placed on the partition plate 6 of the box 20, so that loss of the covering sheet 4 can be eliminated and costs can be reduced. In addition, the covering sheet 4a can be adjusted to a desired size according to the size of the board on which the electronic components are mounted, so that versatility can be significantly improved. In addition, since the covering sheet 4 can be supported by the support layer 8, there is an advantage in that it is easy to realize a thin covering layer.

[0080] 4. Fourth embodiment The laminated sheet according to the fourth embodiment is different from the laminated sheet according to the third embodiment, which does not have the release layer 9, in that the laminated sheet according to the fourth embodiment has a release layer 9 between the support layer 8 and the covering sheet 4a. FIG. 8 shows a schematic plan view of an example of the laminated sheet according to the fourth embodiment, and FIG. 9 shows a cross-sectional view of the IX-IX cut portion of FIG. 8. As shown in these figures, the support layer 8, the release layer 9, and the covering sheet 4a are laminated in this order. The areas of the layers are support layer 8>release layer 9>covering sheet 4a, and in the top view, the frame area of ​​the release layer 9 is on the outside of the covering sheet 4a, and the frame area of ​​the support layer 8 is on the outside of the release layer 9. The support layer 8 has a size that can be placed on the partition plate 6, and the covering sheet 4a has an optimal size for forming a covering layer. The release layer 9 has an area extended from the end of the covering sheet 4a in consideration of ease of peeling after the covering layer is formed. Suitable examples of the release layer 9 include polypropylene (PP) and polyethylene (PE).

[0081] The thickness of the release layer 9 is, for example, about 5 to 1000 μm. From the viewpoint of improving the conformability to the adherend, the thickness is preferably 5 to 500 μm, and more preferably 10 to 250 μm. The Tg of the release layer 9 is preferably -50 to 50°C, and more preferably -20 to 20°C.

[0082] According to the fourth embodiment, by using the release layer 9, it is possible to effectively prevent adhesion between the support layer 8 and the covering sheet 4a, prevent damage to the covering layer 3, and increase the manufacturing yield. It is also possible to significantly increase the options for the material of the support layer 8. Also, it is possible to effectively improve the misalignment of the stacking positions.

[0083] 5. Fifth embodiment The fifth embodiment differs from the first embodiment in that a covering layer is provided on the entirety of one main surface of an electronic component mounting substrate in that a covering layer is provided on a part of one main surface of the electronic component mounting substrate. 10 shows a schematic cross-sectional view of an example of an electronic component mounting board according to the fifth embodiment. A covering layer 3a provided on an electronic component mounting board 11 covers a part of an exposed surface of one main surface of the substrate 1 and the electronic component 2. The partially covered covering layer 3a can be formed, for example, by using the laminate sheet of the third or fourth embodiment.

[0084] According to the electronic component mounting board of the fifth embodiment, a covering layer can be easily formed at a position where protection is required. Moreover, by using the laminated sheet of the third or fourth embodiment, misalignment can be effectively prevented. Moreover, as shown in FIG. 11, a plurality of covering sheets 4 may be laminated on a support layer 8. According to this method, a plurality of covering layers 3 having necessary functions can be formed at a time at desired positions according to the functions required for the electronic component mounting board. EXAMPLES

[0085] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to the following examples. Note that the "parts" and "%" below are values ​​based on "parts by mass" and "% by mass", respectively.

[0086] A. Covering sheet The raw materials used in the examples are shown below. A-1.Thermosetting resin [Synthesis of thermosetting resin r1] A glass flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen inlet tube, and a pressure reducing device was charged with 166 parts of terephthalic acid, 146 parts of adipic acid, 212 parts of 3-methyl-1,5-pentanediol, and 25 parts of ethylene glycol, and stirred while passing nitrogen gas through it. The temperature was gradually increased under normal pressure, and the mixture was reacted at 200 to 230°C for about 8 hours to obtain a liquid with an acid value of 43. Next, 0.01 parts of tetra-n-butoxytitanium was charged, and after nitrogen replacement, the mixture was stirred at 180°C for 30 minutes under a sealed condition. The mixture was then reacted at 230°C and 5mmHg for 2 hours to obtain a polyester diol with an acid value of 1.1, a hydroxyl value of 114.2, and a molecular weight of 982.

[0087] Next, 734 parts of the polyester diol, 23.9 parts of dimethylolpropionic acid, 219 parts of toluene diisocyanate, and 242 parts of toluene were charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, and reacted for 8 hours at 50° C. under a nitrogen atmosphere. 1200 parts of toluene were added to this to obtain a urethane prepolymer solution having an isocyanate group at its end.

[0088] Next, the obtained urethane prepolymer solution was heated to 70°C, and while maintaining the temperature, a solution containing 20.0 parts of 1,3-diaminopropane, 3.1 parts of benzylamine, 600 parts of 2-propanol, and 961 parts of toluene was added dropwise over 1 hour. After the addition was completed, the mixture was allowed to react at 70°C for an additional 6 hours to obtain a polyurethane resin with a molecular weight (Mw) of 130,000, an acid value of 10 mgKOH / g, a Tg of 20°C, and a solid content of 25%.

[0089] A-2. Curing compound Curable compound (c1): Multifunctional epoxy resin "TETRAD-X", manufactured by Mitsubishi Gas Chemical Company, Inc. Curable compound (c2): Epoxy resin "jER828", bifunctional, manufactured by Mitsubishi Chemical Corporation

[0090] A-3.Softening agent Plasticizer p1: Trioctyl trimellitate, manufactured by Mitsubishi Gas Chemical Trading Co., Ltd. A-4. Filler Filler f1: Silica "Ultrasil U360" (DBP oil absorption: 220 mL / 100 g, volume resistivity: 1.6 x 10 16 Ω·cm) NANOCYL

[0091] B. Support layer Support layer X1: polyvinyl chloride sheet made by melt rolling polyvinyl chloride powder (manufactured by Zeon Corporation), Tg: 76°C Support layer X2: polyvinyl chloride sheet made by the solvent method using polyvinyl chloride powder (manufactured by Zeon Corporation), Tg: 54°C

[0092] C.Release layer Release layer Y1: Co-extrusion protective film, Eltec MX 157N3U, manufactured by Nihon Matai Co., Ltd., Tg: -1°C

[0093] D.Measurement method D-1. Glass transition temperature Tg The Tg of the measurement sample (electronic component covering sheet), release layer and support layer of each Example and Comparative Example was measured using a dynamic viscoelasticity measuring device DVA-200 (manufactured by IT Measurement & Control Co., Ltd.) in accordance with JIS K7198. The measurement was performed by cutting the electronic component covering sheet of each Example to 0.5 cm x 3 cm and removing the release film. The deformation mode was tensile, and the temperature at which the main dispersion peak of the loss tangent (tan δ) appeared was determined as Tg, measured at a strain of 0.08%, a frequency of 10 Hz and a heating rate of 10°C / min.

[0094] D-2. Breaking elongation and Young's modulus The electronic component covering sheet with release film of each Example and Comparative Example obtained by the method described below was cut into a size of 20 mm wide x 60 mm long. Next, the release film was peeled off to obtain a measurement sample (electronic component covering sheet) made of the covering sheet. Each measurement sample (covering sheet) was placed in an atmosphere (air, 50% RH) from room temperature to Tg+40°C, and one minute later, a tensile test was performed at that temperature with a tensile speed of 50 mm / min and a relative humidity of 50% using a small tabletop testing machine EZ-TEST (manufactured by Shimadzu Corporation) with an effective tensile size of 20 x 23 mm, and the elongation at break at a tensile speed of 50 mm / min was obtained. In addition, the tangent of the linear region before the yield point was obtained in the stress-strain curve during the tensile test, and the Young's modulus E 50 It was decided. Similarly, the covering sheet was placed in an atmosphere at room temperature to Tg+40°C, and one minute later, a tensile test was carried out at that temperature, under conditions of a tensile speed of 1000 mm / min and a relative humidity of 50%, with an effective tensile size of 20 x 23 mm, to determine the elongation at break at a tensile speed of 1000 mm / min. Furthermore, using the same method with the above device, the Young's modulus E 1000 asked for.

[0095] D-3.Piercing strength The electronic component covering sheets (100 mm x 100 mm) of each example and comparative example were prepared, and the puncture strength per unit thickness at 23 ° C. was measured by a puncture test conforming to JIS Z1707. Specifically, the sample was clamped in a sample mounting jig having an opening of 80 mm in diameter, and placed in a TE-1003 low-temperature and high-temperature peel tester II type (manufactured by Tester Sangyo Co., Ltd.) equipped with a stainless steel rod (length 17 mm) having a diameter of 1 mm as a measurement probe. Under the condition of a measurement temperature of 23 ° C., the probe was penetrated into the electronic component covering sheet at a speed of 100 mm / min, and the strength at the time of breakage was recorded and used as the puncture strength. The puncture strength α per unit thickness was calculated by dividing the obtained puncture strength value by the thickness of the electronic component covering sheet.

[0096] D-4. Film thickness The thickness of the coating layer on the electronic component mounting substrate was measured by polishing the cross-section and measuring the film thickness at the thickest point on the upper surface area of ​​the electronic component with a laser microscope. Five samples of cross-sections of different electronic component mounting substrates were similarly measured, and the average value was taken as the thickness.

[0097] E. Preparation of Electronic Component Covering Sheets and Laminated Sheets [Example 1] 100 parts of thermosetting resin r1 (solid content), 2 parts of curable compound c1, 20 parts of curable compound c2, 5 parts of flexibility regulator, and 22.4 parts of filler f1 were charged into a container, and a mixed solvent of toluene:isopropyl alcohol (mass ratio 2:1) was added so that the non-volatile content concentration was 45 mass%, and the mixture was stirred with a disperser for 10 minutes to obtain a composition. This composition was applied to a release film (polyethylene terephthalate film with release treatment, thickness 50 μm) using a doctor blade so that the dry thickness was 70 μm. Next, the composition was dried at 100 ° C for 2 minutes to obtain an electronic component covering sheet with a release film of Example 1. The obtained electronic component covering sheet with a release film was cut into 60 mm squares, and then the release film was peeled off, and a support layer X1 (300 mm square) having a release function was laminated on the surface where the release film had been laminated, thereby obtaining a laminated sheet (electronic component covering sheet with a support layer) according to Example 1. The electronic component covering sheet was disposed in the center of the support layer X1 in a plan view.

[0098] [Examples 2 to 18, Comparative Examples 1 to 5] Laminate sheets (electronic part covering sheets with a support layer) according to Examples 2 to 18 and Comparative Examples 1 to 5 were obtained in the same manner except that the blending amounts in Tables 1 to 3 were changed.

[0099] [Example 19] 100 parts of thermosetting resin r1 (solid content), 2 parts of curable compound c1, 20 parts of curable compound c2, 5 parts of flexibility regulator, and 22.4 parts of filler f1 were charged in a container, and a mixed solvent of toluene:isopropyl alcohol (mass ratio 2:1) was added so that the non-volatile content concentration was 45% by mass, and the mixture was stirred with a disperser for 10 minutes to obtain a composition. This composition was applied to a release film (polyethylene terephthalate film with release treatment, thickness 50 μm) using a doctor blade so that the dry thickness was 70 μm. Then, the mixture was dried at 100 ° C for 2 minutes to obtain a laminate of release film / first layer α.

[0100] Next, 100 parts of thermosetting resin r1 (solid content), 6.7 parts of curable compound c1, 20 parts of curable compound c2, 5 parts of flexibility regulator, and 23.3 parts of filler 1 were charged into a container, and a mixed solvent of toluene:isopropyl alcohol (mass ratio 2:1) was added so that the non-volatile content concentration was 45 mass%, and the mixture was stirred with a disperser for 10 minutes to obtain a composition. The obtained composition was applied onto the first layer α of the release film / first layer α using a doctor blade so that the dry thickness was 70 μm, thereby obtaining a second layer β. Then, the mixture was dried at 100° C. for 2 minutes to obtain a laminate of release film / first layer α / second layer β.

[0101] The obtained laminate of release film / first layer α / second layer β was cut into 60 mm squares, and the release film was then peeled off. A support layer X1 (300 mm square) having a release function was laminated on the surface where the release film had been laminated in the same manner as in Example 1, thereby obtaining a laminate sheet (support layer / first layer α / second layer β) of Example 19. The first layer α / second layer β corresponds to the electronic component covering sheet.

[0102] [Example 20] A laminate sheet of Example 20 was obtained in the same manner as in Example 19, except that the blending amounts were changed.

[0103] [Example 21] 100 parts of thermosetting resin r1 (solid content), 6.7 parts of curable compound c1, 20 parts of curable compound c2, 5 parts of flexibility regulator, and 23.3 parts of filler 1 were charged in a container, and a mixed solvent of toluene:isopropyl alcohol (mass ratio 2:1) was added so that the non-volatile content concentration was 45 mass%, and the mixture was stirred with a disperser for 10 minutes to obtain the composition. The third layer γ was formed on the second layer β of the release film / first layer α / second layer β using a doctor blade so that the dry thickness was 70 μm. Then, by drying at 100 ° C. for 2 minutes, a laminate consisting of the release film / first layer α / second layer β / third layer γ was obtained. The obtained laminate consisting of release film / first layer α / second layer β / third layer γ was cut into 60 mm squares, and then the release film was peeled off. A support layer X1 (300 mm square) was laminated as a release layer on the surface where the release film had been laminated, thereby obtaining a laminate sheet of support layer / first layer α / second layer β / third layer γ of Example 21.

[0104] [Example 22] A laminate sheet of Example 22 was obtained in the same manner as in Example 21, except that the blending amounts in Table 4 were changed.

[0105] [Example 23] A laminated sheet of Example 23 (support layer X2 / first layer α / second layer β / third layer γ) was obtained in the same manner as in Example 21, except that a laminate of support layer X2 was used instead of support layer X1.

[0106] [Example 24] The laminated sheet of Example 24 (support layer X2 / release layer Y1 / first layer α / second layer β / third layer γ) was obtained in the same manner as in Example 23, except that a release layer Y1 was laminated between the support layer X2 and the first layer α.

[0107] F. Preparation of Test Substrates A substrate made of glass epoxy was prepared with 5 x 5 mold-sealed electronic components (1 cm x 1 cm) mounted in an array. The thickness of the substrate was 0.3 mm, and the mold sealing thickness, i.e., the height from the top surface of the substrate to the top surface of the mold sealing material (component height) H, was 0.7 mm. After that, half dicing was performed along the grooves between the components to obtain a substrate with electronic components mounted (see Figure 12). The half-cut groove depth was 0.8 mm (the cut groove depth of the chain extension described in Substrate 1 was 0.1 mm), and the half-cut groove width was 200 μm. A line was drawn at the edge of a 6 cm x 6 cm area centered on the area where the electronic components were mounted, to identify the area for misalignment evaluation.

[0108] G. Evaluation G-1.TOM aptitude The samples were arranged so that the electronic component covering sheet portion (6 cm x 6 cm) of the laminated sheet of each Example and Comparative Example overlapped the pattern position of the area for evaluating the deviation (6 cm x 6 cm) on the test substrate, and overlay molding was performed at a set temperature of Tg + 40 using a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd.). After peeling off the release layer (support layer, or support layer + release layer), post-baking was performed at 180°C for 60 minutes to obtain an electronic component mounted substrate. The appearance of the obtained electronic component mounted substrate was evaluated in terms of wrinkles and tears according to the following criteria.

[0109] G-2.Wrinkles The number and length of wrinkles present in the electronic component covering layer on the electronic component mounting board were measured and evaluated according to the following criteria. ++++: The number of wrinkles is 0 to 2, and the length of each wrinkle is less than 3 mm. +++: The number of wrinkles is 0 to 2, and the length of each wrinkle is 3 mm or more and less than 5 mm. ++: The number of wrinkles is 3 to 10, and the length of each wrinkle is less than 3 mm. +: The number of wrinkles is 3 to 10, and the length of each wrinkle is 3 mm or more and less than 5 mm. (Practical level) NG: The number of wrinkles is 11 or more, or the length of each wrinkle is 5 mm or more.

[0110] G-3. Torn The number of tears present in the electronic component covering layer on the electronic component mounting board was counted and evaluated according to the following criteria. ++++: The number of tears is between 0 and 1. +++: The number of tears is between 2 and 5. ++: The number of tears is between 6 and 10. +: The number of tears is between 11 and 15. (Practical level) NG: There are 16 or more tears.

[0111] G-4. Stacking position misalignment The distance from the edge of the part where the electronic component covering layer protruded the most from the area on the test substrate for evaluating the misalignment to the edge of the area for evaluating the misalignment was measured, and the amount of misalignment was evaluated according to the following criteria. ++++: The deviation is less than 1 mm. +++: The deviation is 1 mm or more and less than 3 mm. ++: The deviation is 3 mm or more and less than 5 mm. +: The deviation is 5mm or more and less than 7mm. (Practical level) NG: The deviation is 7mm or more.

[0112] G-5. Mold releasability The laminated sheets of each of the examples and comparative examples were cut to 25 mm x 100 mm, and a 75 μm-thick polyimide film ("Kapton 300H" manufactured by Toray DuPont Co., Ltd.) was placed on the electronic component covering sheet side and laminated at 80° C. Next, the obtained samples were peeled between the release layer and the electronic component covering sheet at a peeling speed of 50 mm / min using a tensile tester, and the peel strength was measured. The results were evaluated according to the following criteria. ++++: Peeling is possible at the interface between the release layer and the electronic component covering sheet, and the peeling force is 1 N / cm or less. +++: Peeling is possible at the interface between the release layer and the electronic component covering sheet, and the peeling force is greater than 1 N / cm and less than 2 N / cm. ++: Peeling is possible at the interface between the release layer and the electronic component covering sheet, and the peeling force is greater than 2 N / cm and less than 3 N / cm. +: The release layer and the electronic component covering sheet can be peeled off at the interface, and the peel strength is greater than 3N / cm. (Practical level) NG: Peeling is not possible at the interface between the release layer and the electronic component covering sheet.

[0113] [Table 1]

[0114] [Table 2]

[0115] [Table 3]

[0116] [Table 4]

[0117] It was confirmed that the covering sheet having a breaking elongation of less than 800% in (i) and / or less than 500% in (ii) had a problem with breaking during processing, as shown in Comparative Examples 1, 2, and 5. On the other hand, it was confirmed that the covering sheet having a breaking elongation of more than 2000% in (i) and more than 1500% in (ii) had a problem with wrinkling during processing, as shown in Comparative Example 3. In contrast, it was confirmed that the covering sheet of this example, which satisfies all of the above-mentioned (i) to (iii), was excellent in suppressing wrinkling and breaking during processing, and was also excellent in terms of lamination position misalignment and releasability. [Explanation of symbols]

[0118] 1: Substrate 2: Electronic components 3: Covering layer 4: Electronic component covering sheet 5: Stage 6: Partition plate 7:Heating source 8:Support layer 9: Release layer 10, 11: Electronic component mounting board 20: Box 21: Lower space 22: Upper space 31: Insulating layer 32: Conductive layer 41:First layer 42:Second layer 43:Third layer 50~52: Laminated sheet

Claims

1. An electronic component covering sheet for forming the covering layer of an electronic component mounting substrate, comprising a substrate, electronic components mounted on the substrate, and a covering layer covering at least a portion of the electronic components and the substrate, The aforementioned electronic component covering sheet has multiple layers containing a thermosetting resin and a curable compound. The curable compound contains a curable compound (c1) that is trifunctional or more and has an N atom, and a curable compound (c2) that is bifunctional and does not have an N atom. An electronic component coating sheet comprising a trifunctional or more glycidylamine as the curable compound (c1).

2. The electronic component covering sheet according to Claim 1, wherein the electronic component covering sheet has a three-layer structure in which a first layer, a second layer, and a third layer are laminated in that order.

3. (i) The electronic component coating sheet at room temperature is placed under a temperature of Tg to Tg + 40°C, and the elongation at break measured at a tensile speed of 50 mm / min at that temperature is 800 to 2000%, and (ii) The electronic component coating sheet according to claim 1, wherein the electronic component coating sheet at room temperature is placed under a temperature of Tg to Tg + 40°C, and the elongation at break measured at a tensile speed of 1000 mm / min at that temperature is 500 to 1500%.

4. A laminated sheet comprising a support layer and an electronic component covering sheet as described in claim 1.

5. The laminated sheet according to claim 4, wherein a release layer is provided between the support layer and the electronic component covering sheet.

6. The Tg of the support layer ２ The Tg of the electronic component coating sheet is set to Tg １ In that case, |Tg ２ -Tg １ |≦20℃ The laminated sheet according to claim 4, which is in a relationship with the other.

7. The area of ​​the support layer, the release layer, and the electronic component covering sheet in a plan view is The relationship is: support layer > release layer > electronic component coating sheet. The laminated sheet according to claim 5, wherein, in a plan view, the release layer has a region that extends outward from the edge of the electronic component coating sheet.

8. An electronic component mounting substrate comprising a substrate, electronic components mounted on the substrate, and a covering layer covering at least a portion of the electronic components and the substrate, An electronic component mounting substrate, wherein the coating layer is a layer formed using the electronic component coating sheet described in any one of claims 1 to 3.

9. A method for manufacturing an electronic component mounting substrate, comprising a substrate, an electronic component mounted on the substrate, and a coating layer covering at least a portion of the electronic component and the substrate, The process includes a coating step of forming the coating layer using an electronic component coating sheet according to any one of claims 1 to 3, A method for manufacturing an electronic component mounting substrate, wherein the coating step is performed by one of the following methods: TOM molding, vacuum forming, pressure forming, vacuum pressure forming, press forming, or injection molding.

10. A method for manufacturing an electronic component mounting substrate, comprising a substrate, an electronic component mounted on the substrate, and a coating layer covering at least a portion of the electronic component and the substrate, A coating step of forming the coating layer using the laminated sheet described in any one of claims 4 to 7, The process includes removing layers other than the coating layer from the laminated sheet after the coating process, A method for manufacturing an electronic component mounting substrate, wherein the coating step is performed by one of the following methods: TOM molding, vacuum forming, pressure forming, vacuum pressure forming, press forming, or injection molding.

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