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

Abstract

Provided are: an electronic component coating sheet capable of forming a coating layer of excellent quality that makes it possible to 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. The problem addressed by the present invention is solved by an electronic component coating sheet (4) for use in TOM molding or the like for forming a coating layer (3) of an electronic component mounting substrate (10) comprising a substrate (1), an electronic component (2), and the coating layer (3), wherein the electronic component coating sheet (4) has (i) a breaking elongation of 800-2000% as measured at a tension speed of 50 mm / min at Tg to Tg+40°C, (ii) a breaking elongation of 500-1500% as measured at a tension speed of 1000 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.

Description

Electronic component mounting substrate and its manufacturing method, electronic component covering sheet, and laminated sheet

[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.

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

[0003] The formation of coating layers is being replaced by heat-meltable electronic component covering sheets, instead of conventional conformal coating. For example, Patent Document 1 discloses a method for sealing electronic components by covering electronic components mounted on a substrate with a sheet made of a thermosetting resin composition and then heat-curing the composition. 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 3,500% at its softening point and is provided with pre-formed irregularities corresponding to the irregularities formed on the electronic component-mounted substrate.

[0004] JP 2012-054363 A JP 2019-021757 A

[0005] One known method for applying a film to a three-dimensional shape is the three-dimensional overlay method (TOM) molding. The TOM molding method allows for coating that conforms to the contours of the surface and can impart various functions, such as decorativeness and insulation, making it suitable for decorative applications in automotive interior components. Because the TOM molding method is suitable for coating three-dimensional shapes, it is also promising as a coating layer for electronic component-mounted substrates. However, electronic components are small in size and densely packed with electronic components of different shapes and heights, making coating defects such as wrinkles and breaks in the coating layer more likely to occur. This coating defect not only results in poor appearance, but also in quality and performance degradation. In the case of a coating layer that requires insulation, this can cause insulation defects in electronic component-mounted substrates. Furthermore, in the case of a coating layer that requires electromagnetic wave shielding, this can result in a decrease in shielding properties. These problems can become more serious as products become lighter, thinner, shorter, and smaller. Furthermore, preventing misalignment of the coating layer would enable options such as limiting the coating to the areas that require it. Furthermore, it is expected that the versatility will be significantly improved. Although the above has been described as a problem in TOM molding, similar problems can arise in vacuum molding, pressure molding, vacuum pressure molding, press molding, injection molding, and the like.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose 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.

[0007] As a result of extensive research, the present inventors have found that the problems of the present disclosure can be solved in the following aspects, and have thus completed the present disclosure. [1]: An electronic component covering sheet for forming a covering layer of an electronic component-mounted substrate, the electronic component covering the electronic component and at least a portion of the substrate, the electronic component covering sheet comprising: a substrate; electronic components mounted on the substrate; and a covering layer covering the electronic components and at least a portion of the substrate, wherein: (i) the electronic component covering sheet at room temperature has a breaking elongation of 800 to 2000% when measured at a temperature of Tg of the electronic component covering sheet to Tg + 40°C and at a tensile speed of 50 mm / min at the temperature; (ii) the electronic component covering sheet at room temperature has a breaking elongation of 500 to 1500% when measured at a temperature of Tg of the electronic component covering sheet to Tg + 40°C and at a tensile speed of 1000 mm / min at the temperature; and (iii) the electronic component covering sheet has a puncture strength per unit film thickness of 10 to 200 N / mm at 23°C, as measured in a puncture test in accordance with JIS Z1707. [2]: The electronic component covering sheet at room temperature is placed in a temperature range of Tg to Tg+40°C of the electronic component covering sheet, and the Young's modulus E is measured at the temperature and at a tensile speed of 50 mm / min. ５０ The electronic component covering sheet at room temperature is placed in a temperature range of Tg to Tg+40°C of the electronic component covering sheet, and the Young's modulus E is measured at the temperature and at a tensile speed of 1000 mm / min. １０００ Relative to E １０００ / E ５０ [3]: The electronic component covering sheet according to [1], wherein Tg is 0.8 or more. [4]: ​​The electronic component covering sheet according to [1] or [2], comprising a thermosetting resin and a curable compound, the curable compound containing a trifunctional or higher curable compound (c1) having an N atom, and a bifunctional curable compound (c2) having no N atom. [5]: The electronic component covering sheet according to [4], comprising a support layer and the electronic component covering sheet according to any one of [1] to [3]. [6]: The electronic component covering sheet according to [4], comprising a release layer between the support layer and the electronic component covering sheet. [7]: The electronic component covering sheet according to [6], wherein Tg is set to Tg ２ and the Tg of the electronic part covering sheet is Tg １ When |Tg ２ -Tg １|≦20°C. [7]: An electronic component mounting substrate comprising a substrate, electronic components mounted on the substrate, and a covering layer covering the electronic components and at least a portion of the substrate, wherein the covering layer 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 mounting substrate comprising a substrate, electronic components mounted on the substrate, and a covering layer covering the electronic components and at least a portion of the substrate, the method comprising a covering step of forming the covering layer using the electronic component covering sheet according to any one of [1] to [3], wherein the covering step is carried out by any one of a turn-on-metal molding 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 at least a portion of the electronic components and 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, wherein the coating step is carried out by any one of a TOM forming method, a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a press forming method, and an injection molding method.

[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.

[0009] 8 is a schematic cross-sectional view showing an example of an electronic component mounting substrate according to the first embodiment. FIG. 9 is a schematic cross-sectional view showing an example of an electronic component covering sheet according to the first embodiment. FIG. 10 is a schematic cross-sectional view showing an example of a manufacturing process of the first embodiment. FIG. 11 is a schematic cross-sectional view showing an example of a manufacturing process of the first embodiment. FIG. 12 is a schematic cross-sectional view showing an example of an electronic component covering sheet according to the second embodiment. FIG. 13 is a schematic cross-sectional view showing an example of a laminate sheet and a manufacturing process of the third embodiment. FIG. 14 is a schematic cross-sectional view showing an example of a laminate sheet according to the fourth embodiment. FIG. 15 is a cross-sectional view taken along line IX-IX of FIG. 8. FIG. 16 is a schematic cross-sectional view showing an example of an electronic component mounting substrate according to the fifth embodiment. FIG. 17 is a schematic top view showing an example of a laminate sheet according to the fifth embodiment. FIG. 18 is a schematic side view showing an example of a substrate on which electronic components according to the examples are mounted.

[0010] An example of an embodiment to which the present disclosure is applied will be described below. Each embodiment can be combined as desired. The size and ratio of each component in the following figures are for the sake of convenience and are not limited thereto. Furthermore, in this specification, the expression "any number A to any number B" refers to a range in which number A is the lower limit and number B is the upper limit. Furthermore, the terms sheet and film are synonymous. Furthermore, the numerical values ​​specified in this specification are values ​​determined by the methods disclosed in the embodiments or examples. Furthermore, unless otherwise specified, each component may be used alone or in combination of two or more types.

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

[0012] The substrate 1 can be selected arbitrarily as long as it can mount the electronic component 2 and can withstand the molding process for each application. The substrate 1 can be provided with any electrode / wiring pattern, vias (not shown), and the like. The substrate may be rigid or flexible. Examples include work boards on which a conductive pattern made of copper foil or the like is formed on and / or inside, mounting module boards, printed wiring boards, and build-up boards 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 electronic components may have the same shape and height or may have different shapes and heights. Specific examples of the electronic component 2 include an IC chip, a multilayer ceramic chip capacitor (MLCC), an inductor, and a thermistor.

[0014] The coating layer 3 covers the top and side surfaces of the electronic components 2 and also covers the entire exposed surface of one main surface of the substrate 1. In other words, the coating conforms to the unevenness (concave and convex portions) formed by the mounting of the electronic components 2, and the coating layer 3 is provided on the entire exposed surface of one main surface of the substrate 1. The coating layer 3 is formed using the electronic component coating sheet of the present disclosure (hereinafter also referred to as the present coating sheet). The method for forming the coating layer 3 from the present coating sheet is not limited, but any one of the three-dimensional surface coating methods TOM (Three Dimension Overlay Method) molding, vacuum forming, pressure forming, vacuum pressure forming, press molding, and injection molding is preferred. Among these, the present coating sheet is particularly suitable for TOM molding.

[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 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 electronic components 2 are 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-mounted 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 on an electronic component-mounted substrate. The present covering sheet can physically protect electronic components and also impart specific functions. Suitable examples of the present covering sheet include insulating sheets with insulating properties, conductive sheets that function as electromagnetic wave shielding layers, thermally conductive sheets that dissipate heat from electronic components, shielding sheets that prevent electronic components from being seen or that block light, moisture-proof sheets that protect electronic components from moisture, decorative sheets, flame-retardant sheets that have been imparted with flame retardancy, protective sheets that have been imparted with hard coating properties, and sheets that have any combination of these functions. Suitable examples of covering sheets with multiple functions include covering sheets that combine insulating and thermally conductive properties, covering sheets that combine insulating and shielding properties, covering sheets that combine electrical conductivity and shielding properties, and covering sheets that combine insulating 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 / a conductive layer, an insulating layer / a hard coat layer, an insulating layer / a waterproof layer, or a thermally conductive layer / an insulating layer may be exemplified.

[0019] FIG. 2 is a schematic cross-sectional view of an example of an 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 may be electrically connected to the ground (not shown) of the substrate 1 by a pin (not shown) or the like. Alternatively, the conductive layer 32 may be disposed on the electronic component 2 side, and the insulating layer 31 may be disposed thereon.

[0020] This covering sheet is a precursor article of a covering layer and satisfies the following (i) to (iii). In the case of a multilayer structure, it is not necessary for each layer to satisfy (i) to (iii); it is sufficient for the covering sheet as a whole to satisfy (i) to (iii). (i) When the electronic component covering sheet at room temperature is placed in a temperature range of Tg to Tg + 40°C of the electronic component covering sheet and measured at a tensile speed of 50 mm / min, the breaking elongation is 800 to 2000%. (ii) When the electronic component covering sheet at room temperature is placed in a temperature range of Tg to Tg + 40°C of the electronic component covering sheet and measured at a tensile speed of 1000 mm / min, the breaking elongation is 500 to 1500%. (iii) When the electronic component covering sheet is placed in a puncture test in accordance with JIS Z1707 at 23°C, the puncture strength per unit film thickness is 10 to 200 N / mm. The Tg in the present disclosure is the value obtained by the method of this example. Furthermore, "Tg to Tg + 40°C" is a condition for indicating the characteristics of the electronic component covering sheet, and does not limit the temperature during the formation of the covering layer to this range. Furthermore, the values ​​(i) to (iii) above are values ​​obtained by the method and conditions described in the examples below.

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

[0022] In the present coating sheet, by setting the breaking elongation of (i) above to 800% or more and the breaking elongation of (ii) above to 500% or more, the elongation of the coating sheet can be improved and tearing of the coating layer can be suppressed. On the other hand, by setting the breaking elongation of (i) above to 2000% or less and the breaking elongation of (ii) above to 1500% or less, the occurrence of wrinkles can be suppressed. In the present coating sheet, the control to satisfy the above (i) and (ii) can be adjusted by the type of curable compound in the composition forming the present coating 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. Furthermore, it can be adjusted by the type, amount, and particle size of the filler. It can also be adjusted by using a flexibility adjuster that does not contribute to crosslinking, such as a plasticizer, an inert resin that is not reactive by itself, or an oligomer.

[0023] The puncture strength is a value obtained in a puncture test in accordance with JIS Z1707 (23°C), specifically, the strength at which a stainless steel rod (1 mm in diameter) is dropped perpendicularly onto a covering sheet to break the covering sheet. The puncture strength per unit film thickness is obtained by dividing the puncture strength by the thickness of the covering sheet for electronic components. When the puncture strength per unit film 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 required to satisfy the above condition (iii) can be easily adjusted by adjusting the crosslink density of the coating layer. A suitable method is to adjust the number of functional groups and equivalent weight of the curable compound in the composition for forming the coating sheet. The curable compound is preferably bifunctional or higher, 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 adjuster that does not contribute to crosslinking, such as a plasticizer or an inert resin or 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 coating 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 coating sheet or when the electronic component mounting substrate is subjected to an impact. It is also possible to suppress misalignment of the stacking position. As a result, it is possible to significantly improve the quality of the coating sheet. It is also possible to effectively improve appearance defects. Therefore, with this coating sheet, it is possible to provide an electronic component mounting substrate having a high-quality coating layer, 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 tearing and wrinkling of the coating layer. By making it 900% or more, the strength of the coating sheet can be further increased, and tearing of the coating 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 tearing and wrinkling of the coating layer. The puncture strength per unit film 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 tearing of the coating layer.

[0027] When the covering sheet contains a thermosetting resin, the covering sheet is cured by heating to form a covering layer. The covering sheet may be provided with a release sheet on one or both sides for surface protection.

[0028] Furthermore, from the viewpoint of preventing breakage of the coating layer and improving conformability to the adherend, the present covering sheet is subjected to a temperature of Tg to Tg+40°C of the electronic component covering sheet, and the Young's modulus E is measured at the temperature and at a tension speed of 50 mm / min. ５０ The Young's modulus E of the present covering sheet, which is also at room temperature, is measured at a temperature of Tg to Tg+40°C of the electronic component covering sheet at a tensile speed of 1000 mm / min. １０００It is believed that by setting the Young's modulus at high speed tension within the above range, the sheet will 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 by, for example, adjusting the crosslink density. Specifically, this can be achieved by adjusting the number of functional groups and equivalent weight of the curable compound in the composition for forming the present coating sheet. It can also be adjusted by the content of the curable compound in the composition. Furthermore, 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 adjuster that does not contribute to crosslinking, such as a plasticizer or an inert resin or oligomer that is not reactive by itself.

[0030] Young's modulus E １０００ and Young's modulus E ５０ The ratio E １０００ / E ５０ The ratio E is preferably 0.8 or more. １０００ / E ５０ The ratio E is more 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 of the electronic component, particularly at the edges, can be prevented, and poor appearance can be more effectively prevented.

[0031] The Tg of the present covering sheet is preferably in the range of 0 to 80°C, more preferably 15 to 45°C, from the viewpoint of preventing tearing and wrinkling of the covering layer. When the covering sheet is multilayered, it is preferable that the Tg of each layer is in the above range. In the case of multilayered sheets, the Tg is determined based on the Tg of the layer with the highest Tg.

[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 top and side surfaces of electronic components 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 the present covering sheet is used as an insulating layer, the surface resistance is 1.0 × 10７ It is preferably Ω / □ or more, and 1.0×10 ８ More preferably, it is 1.0×10 ９ When the present covering sheet is used as a conductive layer, the surface resistance is more preferably 1.0×10 ５ It is preferably 1.0×10 Ω / □ or less, ３ It is more preferable that the resistance is Ω / □ or less, and 1.0×10 ２ It is more preferable that the resistance is Ω / □ or less.

[0034] The present coating sheet contains a binder component. The binder component is a component that serves as the base of the coating 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, self-crosslinking thermosetting resins as well as thermosetting resins that can react with curable compounds are suitable. These may also 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 can self-crosslink, 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, or a silanol group.

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

[0037] From the viewpoint of improving edge coating properties, the acid value of the thermosetting resin is preferably 3 to 30 mgKOH / g, more preferably 4 to 20 mgKOH / g, and even more preferably 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 curable compound has 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 compounds can be used alone or in combination of two or more types.

[0039] From the viewpoint of effectively suppressing wrinkling and breakage of the coating 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 preferred. The use of curable compound (c1) promotes the curing reaction before the curing process to some extent, effectively preventing breakage of the coating sheet when stretched during TOM molding or the like. On the other hand, the use of curable compound (c2) reduces the crosslinking density and allows crosslinking to proceed slowly, thereby maintaining good elongation at break during TOM molding or the like.

[0040] Suitable examples of the curable compound (c1) include tri- or higher functional glycidyl amines and tri- or higher functional aziridines, and suitable examples of the curable compound (c2) include bifunctional epoxy compounds.

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

[0042] Examples of 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; tetrafunctional aziridines such as sorbitol pentakis(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, dihydroxybenzoyl ether, and the like. Benzenediol 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 is added to the aromatic ring of diglycidyl ethers selected from the 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 groups of the epoxy compound thermally crosslink with the carboxyl groups or hydroxyl groups of the thermosetting resin, thereby obtaining 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 "Epikote #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, and 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, and 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) to the curable compound (c1) is preferably 3 to 150, and more preferably 3 to 50. By setting the content within the above range, a strong crosslinked structure is formed in the coating layer, excessive curing of the coating layer is suppressed, and conformability to uneven shapes can be improved. Furthermore, a coating layer that can effectively suppress wrinkling and breakage can be formed in a TOM molding method or the like.

[0046] The coating 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 selected appropriately. Examples include flake-shaped, needle-shaped, spherical, dendritic, and fibrous fillers. Fillers of different shapes may also be used in combination. A suitable example is a combination of a flake-shaped filler and a dendritic filler.

[0047] The average particle diameter 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 diameter 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 tearing and wrinkling of the coating layer, the filler content is preferably 1 to 50 mass% and more preferably 1.5 to 35 mass% relative to 100 mass% of the coating sheet. In the case of a multilayer coating, the total of all layers (filler content of n layers × film thickness of n layers / (total film thickness of coating layers)) (where n is an integer of 2 or more) 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, ceramic, etc. The insulating filler may be used alone or in combination of two or more.

[0050] Examples of conductive fillers include metal fillers, conductive ceramic fillers, and mixtures thereof. Examples of metal fillers 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 alloys, Fe—Co alloys, Fe—Cr alloys, Fe—Si alloys, Fe—Al alloys, Fe—Cr—Si alloys, Fe—Cr—Al alloys, and Fe—Si—Al alloys, 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 adjuster. The flexibility adjuster can reduce wrinkling and tearing of the covering sheet during molding. Examples of the flexibility adjuster include plasticizers and inert thermoplastic resins.

[0053] Examples of the plasticizer include fatty acid esters, phthalate esters, aromatic polycarboxylic acid esters, and polyesters. Examples of fatty acid esters include trioctyl trimellitate (TO™), 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, and Panasate 810 (all manufactured by NOF Corp.), DBA, DIBA, DBS, DOA, DINA, DIDA, DOS, BXA, DOZ, and DESU (all manufactured by Daihachi Chemical Industry Co., Ltd.). Examples of phthalate esters include DMP, DEP, DBP, #10, BBP, DOP, DINP, DIDP (hereinafter, manufactured by Daihachi Chemical Industry Co., Ltd.), PL-200, 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 Polycizer TD-1720, Polycizer S-2002, and Polycizer S-2010 (all manufactured by DIC Corporation), and BAA-15 (manufactured by Daihachi Chemical Industry Co., Ltd.). Of these, DMP, DEP, DBP, DOP, DINP, DIDP, and TOTM are more preferred. 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, from the viewpoint of heat resistance, polyamide resins, polyurethane resins, polyester resins, polycarbonate resins, polyimide resins, liquid crystal polymers, and fluororesins are more preferred.

[0055] Furthermore, the coating sheet may contain a tackifying resin to improve adhesion to the substrate. A tackifying 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 resins and binder resins described above. Examples of tackifying resins include rosin-based resins, terpene-based resins, alicyclic petroleum resins, and aromatic petroleum resins.

[0056] The coating sheet may further contain a colorant, a flame retardant, a lubricant, an antiblocking agent, etc. Examples of flame retardants include halogen-containing flame retardants, phosphorus-containing flame retardants, nitrogen-containing flame retardants, and inorganic flame retardants. Examples of lubricants include fatty acid esters, hydrocarbon resins, paraffin, higher fatty acids, fatty acid amides, aliphatic alcohols, metal soaps, and modified silicones. Examples of antiblocking agents include calcium carbonate, silica, polymethylsilsesquioxane, and aluminum silicate.

[0057] In the example of FIG. 2 , an example of a coating sheet consisting of a multilayer structure of insulating layer 31 and conductive layer 32 is shown. However, as mentioned above, the coating sheet may be a single layer, or may be a coating sheet consisting of multiple layers with the same function. Furthermore, a second layer may be patterned at any position on the first layer. For example, by using a coating sheet in which insulating layer 31 is patterned at any position on conductive layer 32, conductive layer 32 can be formed over the entire exposed surface of one main surface of substrate 1, and a coating layer having insulating layer 31 can be formed in areas requiring insulating protection. This coating sheet effectively prevents misalignment of the coating, significantly increasing the design flexibility of the coating sheet.

[0058] 1-3. Manufacturing Method of Electronic Component Covering Sheet The manufacturing method of the covering sheet is not particularly limited, but examples include a method in which a composition in which a material such as the binder resin forming the covering layer is dissolved in a solvent or the like is applied to a release sheet. 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 a multilayer structure, known methods such as lamination and lamination via an easy-to-use adhesive can be applied.

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

[0060] 1-5. Manufacturing Method of Electronic Component Mounting Substrate An example of a TOM molding method for manufacturing an electronic component mounting substrate using the present covering sheet will be described. However, the manufacturing method of the present electronic component mounting substrate is not limited to the following. The covering layer may be formed from the present covering sheet by a method other than TOM molding (e.g., vacuum forming, pressure forming, vacuum pressure forming, press molding, injection molding). For example, a 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 substrate includes steps of mounting one or more electronic components on a substrate (Step A), preparing an electronic component covering sheet cut to a predetermined size (Step B), and forming a covering layer using the covering sheet or a laminated sheet in which the covering sheet is laminated (Step C), thereby obtaining an electronic component mounting substrate that is 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 Figures 3 to 5.

[0062] First, a substrate 1 with electronic components 2 mounted thereon is placed on a stage 5 in the lower space 21 of a box 20 having a lower space 21 and an upper space 22. Next, a cover sheet 4 is placed on a partition plate 6 so as to separate the upper space 22 from the lower space 21 (see FIG. 3 ). The box 20 is then evacuated, and the cover sheet 4 is heated by a heat source 7 to a temperature near the Tg of the cover sheet 4 to soften it. "Around the Tg" refers to, for example, a range of Tg ±20°C. Note that if the cover sheet 4 is multilayered, 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 that sandwiches the sheet may be used instead of a partition plate.

[0063] As the temperature of the covering sheet 4 approaches the temperature around the Tg due to heating by the heat source 7, the covering sheet 4 loses its flatness and undulations appear (see FIG. 4). Further heating reduces the undulation of the covering sheet 4, causing the covering sheet 4 to bend around its center due to its own weight (see FIG. 5). Heating the covering sheet 4 to this state effectively prevents wrinkles from forming in the covering layer, improving quality. Furthermore, to improve adhesion of the covering layer to the substrate 1 and electronic components 2, it is preferable to heat the stage 5 on which the substrate 1 carrying the electronic components 2 is placed. Heating improves production efficiency during continuous production. The temperature of the stage 5 during heating is, for example, 50 to 120°C. From the perspective of improving continuous productivity, it is preferable that the temperature of the stage 5 during heating be 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 portion of the cover sheet 4 into contact with or close to the top surface of the electronic component 2. The surface of the cover sheet 4 is then pressurized from the upper space 22 with atmospheric or compressed air. This causes the cover sheet 4 to conform to the uneven surface of the substrate 1 on which the electronic component 2 is mounted. Next, excess cover sheet is removed. If a thermosetting resin is used as the binder resin, a heat curing treatment is performed, and if a photocurable resin is used, a photocuring treatment is performed. Through these steps, an electronic component-mounted substrate 10 having a cover 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. Furthermore, since the covering sheet is applied to the entire surface to form the 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 requirements (i) to (iii), the present covering sheet can form a high-quality covering layer even on electronic components that are becoming lighter, thinner, and smaller. The TOM molding method allows the present covering sheet to be heated and softened by applying a 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 layer structure as described below, 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 an electronic component covering sheet according to the second embodiment. The electronic component covering sheet 4 a includes a first layer 41, a second layer 42, and a third layer 43, all of which are insulating layers, stacked 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, blending amounts, and layer 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 during TOM molding or the like, and to reduce warpage. For this reason, it is preferable that the curable compound for the first and second layers contains a liquid epoxy compound.

[0070] Liquid epoxy compounds refer to epoxy compounds that are liquid at 25°C. Suitable examples include jER (registered trademark (hereinafter omitted)) YL980, jERYL983U, jER152, jER630, and jERYX8000 (all trade names, manufactured by Mitsubishi Chemical Corporation), EPICLON (registered trademark), and HP-4032 (all trade names, manufactured by DIC Corporation). Liquid epoxy compounds can be used alone or in combination of two or more.

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

[0072] According to the second embodiment, the three-layer structure increases the design flexibility of each layer, thereby improving the functionality of the coating layer, thereby improving the adhesion and conformability of the bonding surfaces between the coating sheet 4 a and the electronic components 2, etc., and effectively preventing wrinkles in the coating layer and breakage at the edges of the coating layer.

[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 of an electronic component mounting substrate according to the third embodiment differs from the manufacturing method of the first embodiment in that a laminate sheet having the present covering sheet is used, but the basic structure of the electronic component mounting substrate and the basic manufacturing method are the same as those of the first embodiment.

[0075] 7 is a schematic diagram showing an example of a manufacturing process for 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 determined to be the size required to form the cover layer. This method makes it possible to omit the step of cutting off unnecessary portions after forming the cover layer.

[0076] Although the manufacturing method of the laminate sheet 50 is not limited, a method of attaching the cover sheet 4 to the desired position of the support layer 8 is simple. A suitable method is, for example, a method of heating the cover sheet 4 to the support layer 8 and temporarily attaching it. The support layer 8 serves to fix the cover sheet 4 during the manufacturing process (in this example, it is placed on and fixed to the partition plate 6) and to support the cover sheet. The support layer can also be called a release layer because it is peeled off after the cover layer is formed. The laminate 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 cover 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, etc. The thickness of the support layer 8 is preferably 5 to 500 μm, more preferably 10 to 250 μm, from the viewpoint of improving conformability to the adherend. The Tg of the support layer 8 is preferably 30 to 90° C., more preferably 40 to 80° C., from the viewpoint of improving conformability to the adherend. The Tg of the covering sheet 4 is set to Tg １ and the Tg of the support layer 8 is Tg ２ When |Tg ２ -Tg １ It is preferable that the relationship of |≦20° C. is satisfied. By setting the temperature in this range, the ability to conform to the uneven shapes of electronic components and the like can be more effectively improved. It is more preferable that |Tg ２ -Tg １ |≦10° C. Tg of the support layer ２ The temperature in the box 20 can be adjusted by the type of resin and the manufacturing conditions. １ and Tg ２ It is preferable to set the temperature within the range of ±20°C, whichever is higher.

[0078] The alignment of 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 achieved 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, which eliminates loss of the covering sheet 4 and reduces costs. Furthermore, the covering sheet 4a can be adjusted to a desired size depending on the size of the substrate on which electronic components are mounted, significantly increasing versatility. Furthermore, since the covering sheet 4a can be supported by the support layer 8, there is an advantage in that it is easy to achieve a thinner covering layer.

[0080] 4. Fourth Embodiment The laminate sheet according to the fourth embodiment differs from the laminate sheet according to the third embodiment, which does not have a release layer 9, in that it has a release layer 9 between the support layer 8 and the covering sheet 4a. FIG. 8 is a schematic plan view illustrating an example of the laminate sheet according to the fourth embodiment, and FIG. 9 is a cross-sectional view taken along line IX-IX 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. In top view, the frame region of the release layer 9 is located outside the covering sheet 4a, and the frame region of the support layer 8 is located outside the release layer 9. The support layer 8 is sized to be placed on the partition plate 6, and the covering sheet 4a is sized optimally for forming the covering layer. The release layer 9 has an area extending beyond the edge of the covering sheet 4a to facilitate 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 conformability to the adherend, it 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 materials for the support layer 8. It is also possible to effectively improve misalignment of the stacking positions.

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

[0084] According to the electronic component mounting substrate of the fifth embodiment, a covering layer can be easily formed in a position where protection is required. Furthermore, by using the laminated sheet of the third or fourth embodiment, misalignment can be effectively prevented. Furthermore, as shown in FIG. 11 , multiple covering sheets 4 may be laminated on a support layer 8. According to this method, multiple covering layers 3 having the required functions can be formed simultaneously in desired positions depending on the functions required of the electronic component mounting substrate.

[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 listed below. A-1. Thermosetting Resin [Synthesis of Thermosetting Resin r1] 166 parts of terephthalic acid, 146 parts of adipic acid, 212 parts of 3-methyl-1,5-pentanediol, and 25 parts of ethylene glycol were charged into a glass flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and pressure reducing equipment, and stirred while passing nitrogen gas through. The temperature was gradually increased under normal pressure, and the mixture was allowed to react at 200-230°C for approximately 8 hours, yielding a liquid with an acid value of 43 mgKOH / g. Next, 0.01 parts of tetra-n-butoxytitanium was charged, and after nitrogen substitution, the mixture was stirred at 180°C for 30 minutes in a sealed container. The mixture was then allowed to react for 2 hours at 230°C and 5 mmHg, yielding a polyester diol with an acid value of 1.1 mgKOH / g, a hydroxyl value of 114.2 mgKOH / g, and a molecular weight of 982. The acid value and hydroxyl value were determined by weighing the thermosetting resin, measuring it using an automatic titrator GT-200 manufactured by Mitsubishi Chemical Analic Corporation in accordance with the potentiometric titration method of JIS K0070, and converting it into a solid content.

[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 placed in 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. To this was added 1,200 parts of toluene to obtain a urethane prepolymer solution having an isocyanate group at its terminal.

[0088] The resulting urethane prepolymer solution was then heated to 70°C, and while maintaining that 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 completion of the dropwise addition, the reaction was continued for an additional 6 hours at 70°C, yielding a polyurethane resin having a molecular weight (Mw) of 130,000, an acid value of 10 mgKOH / g, a Tg of 20°C, and a solids content of 25%.

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

[0090] A-3. Flexibility adjuster 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 × 10 １６ Ω cm) manufactured by NANOCYL

[0091] B. Support layer Support layer X1: Polyvinyl chloride sheet prepared by melt rolling polyvinyl chloride powder (manufactured by Nippon Zeon Co., Ltd.), Tg: 76°C Support layer X2: Polyvinyl chloride sheet prepared by solvent method polyvinyl chloride powder (manufactured by Nippon Zeon Co., Ltd.), Tg: 54°C

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

[0093] D. Measurement Methods D-1. Glass Transition Temperature (Tg) The Tg of the measurement samples (electronic component covering sheets), release layers, and support layers 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. For the measurement, the electronic component covering sheets of each Example were cut to 0.5 cm x 3 cm, and the release film was peeled off. The deformation mode was tensile, and the temperature at which the main dispersion peak of the loss tangent (tan δ) appeared was measured at a strain of 0.08%, a frequency of 10 Hz, and a heating rate of 10°C / min. Tg was defined as the temperature at which the main dispersion peak of the loss tangent (tan δ) appeared.

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

[0095] D-3. Puncture Strength Electronic component covering sheets (100 mm x 100 mm) of each example and comparative example were prepared, and the puncture strength per unit film thickness at 23 ° C was measured using a puncture test in accordance with JIS Z1707. Specifically, the sample was clamped between a sample mounting jig with an 80 mm diameter opening and placed in a TE-1003 low-temperature / high-temperature peel tester Type II (manufactured by Tester Sangyo Co., Ltd.) equipped with a 1 mm diameter stainless steel rod (17 mm long) as a measurement probe. At a measurement temperature of 23 ° C, the probe was penetrated into the electronic component covering sheet at a rate of 100 mm / min, and the strength at break was recorded and used as the puncture strength. The puncture strength α per unit film 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 region of the electronic component with a laser microscope. Five cross section samples 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 Sheet and Laminated Sheet [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 modifier, and 22.4 parts of filler f1 were placed in a container, and a mixed solvent of toluene: isopropyl alcohol (mass ratio 2:1) was added to a non-volatile content of 45% by mass. The mixture was stirred with a disperser for 10 minutes to obtain a composition. This composition was applied to a release film (release-treated polyethylene terephthalate film, thickness 50 μm) using a doctor blade to a dry thickness of 70 μm. The electronic component covering sheet with release film of Example 1 was then obtained by drying at 100 ° C for 2 minutes. The obtained electronic component covering sheet with a release film was cut into 60 mm squares, and then the release film was 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, thereby obtaining a laminated sheet (electronic component covering sheet with a support layer) according to Example 1. The electronic component covering sheet was placed 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 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 modifier, 22.4 parts of filler f1 were placed in a container, and a mixed solvent of toluene: isopropyl alcohol (mass ratio 2:1) was added to the non-volatile content concentration of 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 (a polyethylene terephthalate film with a release treatment, a thickness of 50 μm) using a doctor blade so that the dry thickness was 70 μm. Then, the composition 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 modifier, and 23.3 parts of filler 1 were placed in a container, and a mixed solvent of toluene: isopropyl alcohol (mass ratio 2:1) was added to a non-volatile content of 45% by mass, and the mixture was stirred with a disperser for 10 minutes to obtain a composition. The obtained composition was applied to 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, by drying at 100 ° C. for 2 minutes, a laminate of release film / first layer α / second layer β was obtained.

[0101] The obtained laminate of release film / first layer α / second layer β was cut into 60 mm squares, and then the release film was peeled off. A support layer X1 (300 mm square) having release properties 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 modifier, 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 to a non-volatile content of 45% by mass, and the mixture was stirred with a disperser for 10 minutes to obtain a composition. This composition was then used with a doctor blade to form a third layer γ on the second layer β of a release film / first layer α / second layer β structure to a dry thickness of 70 μm. Then, by drying at 100 ° C. for 2 minutes, a laminate consisting of a 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 onto 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] A 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 was prepared with a 5 x 5 array of mold-sealed electronic components (1 cm x 1 cm) mounted on a glass epoxy substrate. The substrate thickness 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. Half-dicing was then performed along the grooves between the components to obtain a substrate with mounted electronic components (see Figure 12). The half-cut groove depth was 0.8 mm (the cut groove depth for the chain extension described in Substrate 1 was 0.1 mm), and the half-cut groove width was 200 μm. A line was drawn around 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 Suitability Samples were placed so that the electronic component covering sheet portion (6 cm x 6 cm) of the laminate sheet of each Example and Comparative Example overlapped the pattern position of the area for misalignment evaluation (6 cm x 6 cm) on the test substrate, and overlay molding was performed using a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd.) at a set temperature of Tg + 40. 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 using the following criteria.

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

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

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

[0112] G-5. Releasability The laminated sheets of each Example and Comparative Example were cut into 25 mm x 100 mm pieces, 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. The resulting samples were then peeled at a peel rate of 50 mm / min using a tensile tester to measure the peel strength between the release layer and the electronic component covering sheet. The results were evaluated according to the following criteria: ++++: Peeling was possible at the interface between the release layer and the electronic component covering sheet, and the peel strength was 1 N / cm or less. +++: Peeling was possible at the interface between the release layer and the electronic component covering sheet, and the peel strength was greater than 1 N / cm and less than 2 N / cm. ++: Peeling was possible at the interface between the release layer and the electronic component covering sheet, and the peel strength was greater than 2 N / cm and less than 3 N / cm. +: Peeling was possible at the interface between the release layer and the electronic component covering sheet, and the peel strength was greater than 3 N / cm. (Practical level) NG: Peeling was not possible at the interface between the release layer and the electronic component covering sheet.

[0113]

[0114]

[0115]

[0116]

[0117] It was confirmed that a covering sheet having a breaking elongation of less than 800% in (i) and / or less than 500% in (ii) had a problem with tearing during processing, as shown in Comparative Examples 1, 2, and 5. On the other hand, a 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 tearing during processing, and was also excellent in preventing misalignment of the lamination and in releasability.

[0118] This application claims priority based on Japanese Patent Application No. 2023-128861, filed on August 7, 2023, the disclosure of which is incorporated herein in its entirety by reference.

[0119] 1: Substrate 2: Electronic component 3: Covering layer 4: Electronic component covering sheet 5: Stage 6: Partition plate 7: Heat source 8: Support layer 9: Release layer 10, 11: Electronic component mounting substrate 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 sheets

Claims

1. An electronic component covering sheet for forming a covering layer of an electronic component mounting substrate, the electronic component covering the 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 electronic component covering sheet comprising: (i) a breaking elongation of the electronic component covering sheet at room temperature, measured at a temperature of Tg to Tg+40°C of the electronic component covering sheet and at a tensile speed of 50 mm / min, is 800 to 2000%, (ii) a breaking elongation of the electronic component covering sheet at room temperature, measured at a temperature of Tg to Tg+40°C of the electronic component covering sheet and at a tensile speed of 1000 mm / min, is 500 to 1500%, and (iii) a puncture strength per unit film thickness at 23°C, measured in a puncture test in accordance with JIS Z1707, is 10 to 200 N / mm.

2. The electronic component covering sheet at room temperature is placed in a temperature range of Tg to Tg+40°C of the electronic component covering sheet, and the Young's modulus E is measured at a tensile speed of 50 mm / min at that temperature. ５０ The electronic component covering sheet at room temperature is placed in a temperature range of Tg to Tg+40° C. of the electronic component covering sheet, and the Young's modulus E is measured at the temperature and at a tensile speed of 1000 mm / min. １０００ Comparison with E １０００ / E ５０ The electronic part covering sheet according to claim 1 , wherein the thickness of the electronic part covering sheet is 0.8 or more.

3. The electronic component covering sheet according to claim 1, comprising a thermosetting resin and a curable compound, the curable compound comprising: a trifunctional or higher curable compound (c1) having an N atom; and 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 claim 1.

5. The laminate sheet according to claim 4, further comprising a release layer between said support layer and said electronic part covering sheet.

6. The Tg of the support layer is Tg ２ and the Tg of the electronic part covering sheet is Tg １ When |Tg ２ -Tg １ The laminate sheet according to claim 4, wherein the relationship is |≦20° C.

7. An electronic component mounting substrate comprising a substrate, electronic components mounted on the substrate, and a covering layer covering the electronic components and at least a portion of the substrate, the covering layer being a layer formed using an electronic component covering sheet according to any one of claims 1 to 3.

8. A method for manufacturing an electronic component-mounted substrate comprising a substrate, electronic components mounted on the substrate, and a covering layer covering the electronic components and at least a portion of the substrate, the method comprising a covering step of forming the covering layer using an electronic component covering sheet according to any one of claims 1 to 3, the covering step being carried out by any one of TOM forming, vacuum forming, pressure forming, vacuum pressure forming, press forming, and injection molding.

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, comprising: a coating step of forming the coating layer using a laminated sheet according to any one of claims 4 to 6; and a step of removing layers of the laminated sheet other than the coating layer after the coating step, wherein the coating step is carried out by any one of TOM forming, vacuum forming, pressure forming, vacuum pressure forming, press forming, and injection molding.

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