Electronic component covering sheet, electronic component mounting substrate, and method for manufacturing the same

Abstract

The present invention provides a highly productive electronic component coating sheet, an electronic component mounting substrate, and a method for manufacturing the same, which are suitable for use in pick-and-place technology. [Solution] An electronic component coating sheet 10 for forming a coating layer for an electronic component mounting substrate, comprising a substrate 1, an electronic component 2 mounted on the substrate 1, and a coating layer covering at least a part of the electronic component 2 and the substrate 1, wherein the ratio [H2] / [H1] of the hardness [H1] of the surface 16 of the electronic component coating sheet 10 opposite to the surface 15 facing the electronic component 2, measured by nanoindentation, is 1.00 to 50.00.

Description

[Technical Field]

[0001] This disclosure relates to an electronic component coating sheet, and also to an electronic component mounting substrate and a method for manufacturing the same. [Background technology]

[0002] To protect electronic components such as IC chips mounted on circuit boards from bending, impact, and thermal shock caused by temperature changes, liquid encapsulation methods have traditionally been employed. In this method, a liquid resin composition is applied to the circuit board on which the electronic components are mounted and then cured to cover and protect the components. However, liquid encapsulation methods require application and curing processes, and are not considered highly efficient. Furthermore, it is difficult to ensure uniformity of the encapsulation thickness, and the fluidity of the liquid makes it prone to uneven filling between components and the inclusion of air bubbles. In addition, there is the problem of volatile components being released during curing.

[0003] As a means of solving these problems, heat-meltable electronic component coating sheets have been proposed. For example, Patent Document 1 proposes a thermosetting encapsulating sheet in which the product α of the thickness t [mm] and the storage modulus G' [Pa] at 50°C is within a specific range, which is suitable for embedding semiconductor chips. Patent Document 2 also proposes an encapsulating resin sheet having a first encapsulating resin layer with a high tensile storage modulus and an encapsulating resin layer having a first encapsulating resin layer with a low tensile storage modulus. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-50240 [Patent Document 2] Japanese Patent Publication No. 2021-197495 [Overview of the project] [Problems that the invention aims to solve]

[0005] Heat-meltable electronic component coating sheets do not contain solvents and can be molded by heating. This characteristic simplifies the manufacturing process and improves the uniformity of the encapsulation. Therefore, as electronic components and circuit boards become more high-performance and smaller, the demand for heat-meltable electronic component coating sheets is increasing. Pick-and-place technology has traditionally been used in semiconductor manufacturing and electronic circuit board assembly. This method involves picking up semiconductor chips and other components, transporting them to a desired location, and placing them precisely in that position, resulting in excellent productivity. Applying this method to electronic component coating sheets can dramatically increase productivity.

[0006] This disclosure is made in view of the above background, and aims to provide a highly productive electronic component coating sheet, an electronic component mounting substrate, and a method for manufacturing the same, which can be suitably used in pick-and-place technology. [Means for solving the problem]

[0007] After diligent research by the present inventors, we have found that the problems of this disclosure can be solved in the following embodiments, and have completed this disclosure. [1]: An electronic component covering sheet for forming the covering layer of an electronic component mounting substrate, comprising a substrate, an electronic component mounted on the substrate, and a covering layer covering at least a part of the electronic component and the substrate, An electronic component coating sheet having a ratio [H2] / [H1] of the hardness [H1] of the surface of the electronic component coating sheet opposite to the surface facing the electronic component, measured by nanoindentation, where [H2] / [H1] is between 1.00 and 50.00. [2]: The electronic component coating sheet according to [1], wherein the sum of the composite elastic modulus [E1] of the opposing surface of the electronic component coating sheet and the composite elastic modulus [E2] of the surface layer of the electronic component coating sheet, [E1]+[E2], measured by nanoindentation, is 10 MPa or more. [3]: The electronic component coating sheet according to [1] or [2], wherein the hardness [H1] of the opposing surface of the electronic component coating sheet, as measured by nanoindentation, is 15.0 MPa or less. [4]: An electronic component coating sheet according to any one of [1] to [3], wherein the composite elastic modulus [E2] of the surface layer of the electronic component coating sheet, as measured by nanoindentation, is 8 MPa or greater. [5]: An electronic component coating sheet according to any one of [1] to [4], wherein the hardness [H2c] of the surface layer of the cured sheet obtained by curing the electronic component coating sheet at 160°C for 2 hours, as measured by nanoindentation, is 1.0 MPa or higher. [6]: An electronic component coating sheet according to any one of [1] to [4], wherein the ratio [E2c] / [E2] of the composite elastic modulus [E2c] of the surface layer of a cured sheet obtained by curing the electronic component coating sheet at 160°C for 2 hours to the composite elastic modulus [E2] of the surface layer of the electronic component coating sheet, as measured by nanoindentation, is 0.5 to 25.0. [7]: An electronic component coating sheet according to any of [1] to [6], containing a thermosetting resin (A) with a functional group concentration of 10 to 550 mmol / kg. [8]: A substrate comprising a substrate, an electronic component mounted on the substrate, and a covering layer covering at least a portion of the electronic component and the substrate, wherein the covering layer is formed from a cured product of an electronic component covering sheet according to any one of [1] to [7]. [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 part of the electronic component and the substrate, The steps include: placing an electronic component covering sheet according to any of [1] to [7] on the substrate on which the electronic component is mounted; A step of forming the coating layer that covers the electronic component and at least a portion of the substrate using the electronic component coating sheet, A method for manufacturing an electronic component mounting substrate, comprising a step of curing the aforementioned coating layer.

[10] : The step of forming the coating layer is performed without pressure or while applying pressure in the method for manufacturing an electronic component mounting substrate described in [9].

Advantages of the Invention

[0008] According to the present disclosure, there is an excellent effect that a highly productive electronic component coating sheet, an electronic component mounting substrate, and a method for manufacturing the same that can be suitably used for the pick-and-place technology can be provided.

Brief Description of the Drawings

[0009] [Figure 1] A schematic cross-sectional view showing an example of an electronic component mounting substrate according to the present embodiment. [Figure 2] A schematic cross-sectional view showing another example of an electronic component mounting substrate according to the present embodiment. [Figure 3] A schematic cross-sectional view showing an example of an electronic component coating sheet according to the present embodiment. [Figure 4] A schematic cross-sectional view showing another example of an electronic component coating sheet according to the present embodiment. [Figure 5] A schematic cross-sectional view showing still another example of an electronic component coating sheet according to the present embodiment. [Figure 6] (a) to (d): Schematic side views for explaining the pick-and-place method. [Figure 7] [[ID=?]] (a), (b): Schematic side views for explaining the method of measuring the hardness and complex elastic modulus of the sheet surface by the nanoindentation method.<000008* [Figure 8] A graph showing an example of a load-displacement curve obtained by the nanoindentation method. [Figure 9] An explanatory diagram of the method for evaluating the conveyance suitability of the electronic component coating sheet of the example.

Modes for Carrying Out the Invention

[0010] The following describes an example of an embodiment to which this disclosure applies. In this specification, numerical ranges indicated by "~" include the values ​​described before and after them as the minimum and maximum values, unless otherwise specified. The drawings have been simplified as appropriate for clarity of explanation, and the scale of each component may differ. Unless otherwise noted, the various components described in this specification can be used individually or in combination of two or more. When two or more are used in combination, the total content value is used. Furthermore, the numerical values ​​specified in this specification are values ​​obtained by the methods of the examples described later.

[0011] <Electronic component mounting substrate and method for manufacturing the same> The electronic component mounting substrate according to this disclosure (hereinafter also referred to as "this mounting substrate") comprises a substrate, electronic components mounted on the substrate, and a coating layer covering at least a portion of the electronic components and the substrate. The coating layer is formed using the electronic component coating sheet according to this disclosure (hereinafter also referred to as "this coating sheet"). Hereinafter, Figures 1 and 2 show two examples of schematic cross-sectional views of the electronic component mounting substrate according to this embodiment.

[0012] The electronic component mounting substrate 101 shown in Figure 1 comprises a substrate 1, an electronic component 2 mounted on the substrate 1, and a coating layer 3. The coating layer 3 covers the entire exposed surface of one main surface of the electronic component mounting substrate. On the other hand, the electronic component mounting substrate 102 shown in Figure 2 has a coating layer 3a provided on a part of one main surface of the electronic component mounting substrate. The coating layer 3a covers a part of the exposed surface of the substrate 1 and one main surface of the electronic component 2. Thus, in this mounting substrate, the coating layer formed using the electronic component coating sheet according to this disclosure may be provided so as to cover a part of the electronic component and the substrate, or it may be provided so as to cover the entire surface of the electronic component and the substrate.

[0013] The substrate 1 can be any substrate that can mount electronic components 2 and withstand the molding process for each application, and can be arbitrarily selected. Electrode and wiring patterns, vias (not shown), etc., can be optionally provided on the substrate 1. The substrate may be either a rigid substrate or a flexible substrate. Examples include workboards, mounting module substrates, printed circuit boards, and build-up substrates formed by build-up methods, etc., with conductive patterns made of copper foil or the like formed on the surface and / or inside.

[0014] Electronic component 2 is mounted on the main surface of substrate 1. When multiple electronic components are mounted, their shapes and heights may be the same or different. Specific examples of electronic component 2 include IC chips, multilayer ceramic chip capacitors (MLCCs), inductors, and thermistors.

[0015] The coating layers 3 and 3a cover the top surface and sides of the electronic component 2, and further, the entire or partial surface of one main surface of the substrate 1. In other words, the coating follows the stepped portions (uneven portions) formed by the mounting of the electronic component 2, and the coating layers 3 and 3a are provided on the entire or partial surface of one main surface of the substrate 1. The coating layers 3 and 3a are formed using the electronic component coating sheet (the coating sheet) according to this disclosure, and are cured products obtained by curing the coating sheet. In this specification, the coating sheet is uncured or semi-cured (so-called B-stage). In contrast, the coating layers 3 and 3a of the electronic component mounted substrate after manufacturing are cured products of the coating sheet, and the coating sheet has been fully cured.

[0016] The electronic component mounting substrate of this disclosure comprises the steps of: placing the coating sheet on a substrate on which the electronic component is mounted; forming a coating layer using the coating sheet that covers at least a portion of the electronic component and the substrate; and curing the coating layer.

[0017] The method for forming the coating layers 3 and 3a from this coating sheet is not limited, but preferred examples include press molding, the three-dimensional surface coating method TOM (Three-dimensional Overlay Method) molding, vacuum forming, pressure forming, vacuum pressure forming, injection molding, and pick-and-place methods. Among these, the pick-and-place method is particularly suitable for manufacturing this coating sheet.

[0018] The coating layers 3 and 3a consist of an insulating single or multi-layer structure. The coating layers can be given functions according to needs. For example, they may be given thermal conductivity, waterproofing, shielding, colorability, flame retardancy, hard coating properties, decorative properties, etc. In addition to protecting the exposed surface of the main surface of the substrate 1 with the coating layer 3, the sides of the substrate 1 may also be protected with the coating layer 3 as shown in Figure 1. In the examples in Figures 1 and 2, an example in which an electronic component 2 is mounted on one main surface of the substrate 1 is 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 the coating layer.

[0019] Because this mounting substrate uses the electronic component coating sheet described later in this disclosure, the coating layer exhibits excellent conformability to the electronic components. Furthermore, high dimensional accuracy of the coating layer can be achieved. In addition, this mounting substrate is particularly suitable for the pick-and-place method, resulting in excellent productivity.

[0020] <Electronic component covering sheet> As described above, the electronic component coating sheet (the coating sheet) relating to this disclosure is suitably used as a sheet for forming a coating layer on an electronic component mounting substrate. Figures 3 to 5 show three examples of schematic cross-sectional views of electronic component coating sheets according to this disclosure. The electronic component coating sheet 10 shown in Figure 3 consists of a single layer of first layer 11. The electronic component coating sheet 10a shown in Figure 4 has a laminated structure of first layer 21 and second layer 22. The electronic component coating sheet 10b shown in Figure 5 has a laminated structure in which first layer 31, second layer 32 and third layer 33 are laminated in this order. The number of layers may be four or more. The electronic component coating sheet may have a release sheet on one or both sides for surface protection.

[0021] This covering sheet is an insulating sheet that physically protects electronic components and can also provide them with specific functions. If the electronic component covering sheet is multilayered, each layer may have the same function or different functions.

[0022] From the viewpoint of freely adjusting the hardness [H1] of the opposing surface of the coating sheet, the hardness [H2] of the surface layer, the composite elastic modulus [E1] of the opposing surface, and the composite elastic modulus [E2] of the surface layer, it is preferable that the coating sheet be multi-layered. In the case of a single layer, for example, one method is to adjust the coating conditions so that the inorganic filler (F) content is higher on the surface layer than on the opposing surface. For example, when manufacturing the coating sheet, one method is to carry out the drying process slowly so that the inorganic filler (F) settles easily.

[0023] Each layer of this coating sheet can be given various functions such as heat dissipation, light shielding, moisture resistance, decorative properties, hard coating properties, flame retardancy, and gas barrier properties. These properties can be provided, for example, by selecting an inorganic filler (F) as described later. The layer of this coating sheet placed on the electronic component side preferably has excellent adhesion to the electronic component.

[0024] For this coating sheet, it is important that the ratio [H2] / [H1], which is the ratio of the hardness [H1] of the surface facing the electronic component to the hardness [H2] of the surface opposite to the surface facing the electronic component, measured by nanoindentation, is between 1.00 and 50.00.

[0025] In the example in Figure 3, the first layer 11 constituting the electronic component covering sheet 10 has a facing surface 15 on the side facing the electronic component 2 and a main surface, the surface layer 16, opposite to the facing surface 15, and the ratio of the hardness [H2] of the surface layer 16 to the hardness [H1] of the facing surface 15, [H2] / [H1], satisfies the above range. In the example in Figure 4, the surface of the first layer 21 constituting the electronic component covering sheet 10a is the facing surface 25 facing the electronic component 2, and the surface of the second layer 22 is the surface layer 26. In the example in Figure 5, the surface of the first layer 31 constituting the electronic component covering sheet 10b is the facing surface 35 facing the electronic component 2, and the surface of the third layer 33 is the surface layer 36. In the examples in Figures 4 and 5, [H2] / [H1] is set to 1.00 to 50.00.

[0026] In this context, nanoindentation is a method for determining the hardness and composite modulus of a minute region on the surface of a sample by pressing a nanometer-precision indenter into the sample and analyzing the resulting load and displacement. In this example, indentation tests were performed using a diamond indenter to depths on the order of several tens of nanometers to several tens of micrometers, and the indentation depth and load curve of the indenter were measured while applying minute loads in stages.

[0027] Figure 7 shows an explanatory diagram of hardness measurement using the nanoindentation method. A diamond indenter 61 is placed opposite the electronic component coated sheet 10, which is the sample to be measured (Figure 7(a)), and a load is applied to the electronic component coated sheet 10 and held at the maximum load (Figure 7(b)). Then the diamond indenter 61 is unloaded. When the load and displacement of the indentation depth at this time are graphed, a load-displacement curve like the one shown in Figure 8 is obtained.

[0028] The hardness of the sheet surface can be determined from the load-displacement curve obtained by measurement using the following formula (1). Hardness H[MPa]=Pmax / Ac...(1) (Pmax: maximum load, Ac: projected contact area) Here, the contact projection area is the deformation mark after unloading. In the nanoindentation method, the load is very small, so Ac cannot be directly determined from the indentation. Therefore, as shown in Figure 7, the equation hc = hmax - ε·Pmax / S (where ε is a variable that depends on the indenter shape, and is 0.75 in the case of a barco pitch indenter; S is the slope as shown in Figure 8) holds, and Ac = f(hc). Also, the composite modulus of elasticity [E] is given by E = S·π 1 / 2 / 2 / Ac 1 / 2 It can be calculated from this. A larger composite modulus of elasticity [E] suggests that plastic deformation is more likely, while a smaller composite modulus [E] suggests that elastic deformation is more likely.

[0029] In this coating sheet, the ratio [H2] / [H1] of the hardness [H1] of the surface facing the electronic component to the hardness [H2] of the opposite surface (the surface layer) is 1.00 to 50.00, thereby improving the pick-and-place properties of the coating sheet. Furthermore, positional displacement of the coating sheet with respect to the component on which it is placed can be effectively suppressed during picking. Additionally, adhesion to the electronic component is improved during placing, and positional displacement can be suppressed until processing. The lower limit of [H2] / [H1] is preferably 2.50, more preferably 5.00, and even more preferably 10.00. The upper limit of [H2] / [H1] is preferably 48.00, more preferably 45.00, and even more preferably 40.00.

[0030] The upper limit of the hardness [H1] of the opposing surface is preferably 15.0 MPa, more preferably 12.0 MPa, more preferably 10.0 MPa, and even more preferably 5.0 MPa. Having a hardness [H1] of 15.0 MPa or less on the opposing surface effectively improves the coverage between electronic components. The lower limit of the hardness [H1] of the opposing surface is preferably 0.1 MPa, more preferably 0.2 MPa, more preferably 0.3 MPa, and even more preferably 0.4 MPa. Having a hardness [H1] of 0.1 MPa or more on the opposing surface improves the coverage of electronic components.

[0031] The lower limit of the surface hardness [H2] is preferably 0.1 MPa, more preferably 1.0 MPa, even more preferably 2.0 MPa, and even more preferably 4.0 MPa. The upper limit of the surface hardness [H2] is preferably 50.0 MPa, more preferably 30.0 MPa, even more preferably 20.0 MPa, and even more preferably 15.0 MPa.

[0032] Here, we will explain the method for manufacturing this mounting substrate using the pick-and-place method, with reference to Figure 6. The following explanation will use the coating sheet shown in Figure 3 as an example. The coating sheet 10 is cut to a size suitable for use as a coating layer on an electronic component mounting substrate. Next, if a release film is laminated on the opposing surface 15 and / or the surface layer 16 of the coating sheet 10, the release film is removed and the sheet is placed so that the opposing surface 15 is in contact with the carrier film 50 (see Figure 6(a)). A substrate such as a glass plate, plastic plate, ceramic plate, or metal plate may be used instead of the carrier film 50. Alternatively, the coating sheet 10, which has been cut to the desired size in advance, can be placed on the release film to form a roll, and then this roll can be unwound to use the release film as the carrier film.

[0033] Next, the covering sheet 10 placed on the carrier film 50 is picked up by suction onto a plate 51 of a pick-and-place device (not shown) (see Figure 6(b)). A suction type is preferred as the picking method. In the suction type, for example, a plurality of micropores are provided on the surface of the plate 51 that contacts the covering sheet, and the covering sheet 10 is held by suction through these micropores. When suction is stopped, the covering sheet is released from the plate 51. To prevent the covering sheet 10 from bending or wrinkling during suction, it is preferable that the hardness [H2] of the surface layer of the covering sheet 10 is high.

[0034] The covering sheet 10 picked up by the plate 51 is transported to a desired position on the substrate 1 on which the electronic component 2 is mounted (see Figure 6(c)). Accurate positioning of the covering sheet 10 is important to improve yield. Methods for adjusting the position to improve positional accuracy include methods using imaging devices such as cameras or laser beams, positioning methods using non-imaging sensors such as ultrasonic sensors, or control methods using position adjustment units for the mounting base of the plate 51 and the electronic component substrate. The position and angle of the covering sheet may be corrected while observing with an imaging device. Alternatively, the imaging device or sensors may be positioned by automatic control.

[0035] The coating sheet 10 is accurately transported to the position on the substrate 1 on which the electronic components are mounted where the coating layer 3 will be applied, and then placed on the electronic components 2 (see Figure 6(d)). In the case of suction type, the coating sheet 10 is released from the plate 51 by releasing the suction, and the coating sheet 10 is placed on the electronic components. By reducing the hardness [H1] of the opposing surface 15 of the coating sheet 10, positional displacement on the electronic components 2 can be effectively suppressed. In addition, to prevent positional displacement, heating or other methods may be performed at the time the coating sheet 10 is placed on the electronic components 2 to temporarily bond it.

[0036] With this coating sheet, by setting the [H2] / [H1] ratio to 1.00 to 50.00, excellent pick-and-place properties can be achieved. Within this range, the greater the hardness [H2] of the surface layer and the smaller the hardness [H1] of the opposing surface, the better the performance. The main reason for this is that a greater hardness [H2] of the surface layer allows for superior suction and detachment of the suction / desorption unit that picks up the coating sheet. For example, when the coating sheet is picked up by a suction nozzle, a greater hardness [H2] of the surface layer makes it easier to suction. Also, during placement, the sheet detaches more easily when the suction is released. On the other hand, a smaller hardness [H1] of the opposing surface reduces the likelihood of misalignment between the coating sheet and the mounting member on which it is placed before picking. Furthermore, it improves adhesion with electronic components during placement and effectively suppresses misalignment of the coating sheet during the process from placement to the formation of the coating layer. As a result, the accuracy of the installation position of this coating sheet is significantly improved. For these reasons, this coating sheet is suitable for the pick-and-place method and can provide a highly productive coating sheet for electronic components.

[0037] In this coating sheet, the hardness [H1] of the opposing surface and the hardness [H2] of the surface layer can be controlled by, for example, the type of thermosetting resin (R), glass transition temperature (Tg), weight-average molecular weight (Mw), and functional group concentration, as described later. For example, a lower Tg of the thermosetting resin (R) tends to result in lower hardness, while a higher Tg tends to result in higher hardness. It can also be adjusted by the type and amount of curable compound (C), or by the crosslinking density of the three-dimensional network structure formed by the curing treatment. For example, using a liquid epoxy compound as the curable compound (C) tends to result in lower hardness, while using a solid epoxy compound tends to result in higher hardness. Furthermore, the hardness can be adjusted by the type, particle size, particle shape, and amount of filler (F). To increase hardness, for example, increasing the density of the three-dimensional network structure tends to increase hardness, so increasing the functional group concentration of the thermosetting resin (R) or increasing the amount of curable compound (C) is effective. Furthermore, increasing the concentration of filler on the surface of the coated sheet also tends to increase hardness. To lower the hardness, the opposite adjustments can be made. In the case of a single layer as shown in Figure 3, for example, by adjusting the filler concentration, a microscopic distribution of density can be created within the coating sheet, thereby allowing adjustment of the hardness [H2] of the surface layer and the hardness [H1] of the opposing surface. In the case of a two-layer structure as shown in Figure 4, for example, the first layer 21 facing the electronic component may be made using a curable compound (C) containing a thermosetting resin (R) and a liquid curable compound (C), and an inorganic filler (F) may be added in an amount of, for example, 20% by mass or less. The second layer 22, which is placed on one of the surface layers, may be made using a curable compound (C) containing a thermosetting resin (R) and a solid curable compound (C), and an inorganic filler (F) may be added in an amount of, for example, 10% by mass or more.

[0038] In the pick-and-place method, from the viewpoint of improving the transportability of the coating sheet, it is preferable that the sum of the composite modulus [E1] of the opposing surface (the surface in contact with the electronic component) and the composite modulus [E2] of the surface (the surface opposite to the opposing surface) of the coating sheet, measured by nanoindentation, [E1]+[E2] is 10 MPa or more. The lower limit of [E1]+[E2] is more preferably 20 MPa, even more preferably 50 MPa, and even more preferably 100 MPa. The upper limit of [E1]+[E2] is preferably 1500 MPa, more preferably 1400 MPa, even more preferably 1300 MPa, and even more preferably 1200 MPa. By setting the sum of the composite moduli [E1]+[E2] to 10 MPa or more, the yield in the pick-and-place process can be increased.

[0039] The lower limit of the composite modulus [E1] of the opposing surface is preferably 2 MPa, more preferably 3 MPa, even more preferably 4 MPa, and even more preferably 5 MPa. The upper limit of the composite modulus [E1] of the opposing surface is preferably 800 MPa, more preferably 700 MPa, even more preferably 600 MPa, and even more preferably 500 MPa.

[0040] The lower limit of the composite modulus [E2] of the outermost surface is preferably 8 MPa, more preferably 15 MPa, even more preferably 30 MPa, and even more preferably 60 MPa. The upper limit of the composite modulus [E1] of the opposing surface is preferably 1000 MPa, more preferably 900 MPa, even more preferably 800 MPa, and even more preferably 700 MPa. By setting [E2] to 8 MPa or higher, it is possible to effectively prevent the coating sheet from shrinking due to thermal melting when covering electronic components with this coating sheet, thereby improving dimensional stability. Furthermore, it is possible to suppress the expansion of the coating sheet when it is pressed during thermal melting, thereby improving dimensional stability.

[0041] In this coating sheet, the composite modulus [E1] of the opposing surface and the composite modulus [E2] of the surface can be controlled, for example, by the type of thermosetting resin (R), the weight-average molecular weight Mw, and the functional group concentration. Furthermore, it can be adjusted by the type and amount of curable compound (C), and even the amount of filler (F). Additionally, using liquid epoxy compounds tends to result in a lower composite modulus, while using solid epoxy compounds tends to result in a higher composite modulus. One way to increase the composite modulus is to increase the cohesive force of the coated sheet, which tends to increase the composite modulus. Therefore, increasing the functional group concentration of the thermosetting resin (R) is an effective method. Furthermore, by having aromatic ring skeletons, urethane bonds, ester bonds, etc., in the thermosetting resin (R), the flexibility of the coated sheet can be increased while increasing the elongation at break, thus increasing the composite modulus. In addition, by using hydroxyl groups or carboxyl groups as functional groups of the thermosetting resin (R), pseudo-crosslinking is formed by hydrogen bonding. Unlike crosslinking by crosslinking agents, this pseudo-crosslinked structure is due to reversible intermolecular interactions by hydrogen bonding, making it easy to adjust the composite modulus of the sheet without impairing curability or processability. The composite modulus tends to increase as the amount of pseudo-crosslinked structure increases. Furthermore, the composite modulus can be controlled by adjusting the coated sheet to a semi-cured state at the stage of the coated sheet by adjusting the skeleton and amount of curable compound (C).

[0042] From the viewpoint of improving the moisture heat resistance of the coating layer covering the electronic components, the hardness [H2c] of the surface layer of the cured sheet obtained by curing the coating sheet at 160°C for 2 hours, as measured by nanoindentation, is preferably 1.0 MPa or higher. The lower limit of the hardness [H2c] is more preferably 1.5 MPa, even more preferably 2.0 MPa, and even more preferably 4.0 MPa. The upper limit of the hardness [H2c] is preferably 100.0 MPa, more preferably 95.0 MPa, even more preferably 90.0 MPa, and even more preferably 85.0 MPa.

[0043] The hardness [H1c] of the opposing surface of the cured sheet, obtained by curing the coating sheet at 160°C for 2 hours, as measured by nanoindentation, is preferably 0.9 MPa or higher. The lower limit of the hardness [H1c] is more preferably 1.4 MPa, even more preferably 1.8 MPa, and even more preferably 3.6 MPa. The upper limit of the hardness [H1c] is preferably 90.0 MPa, more preferably 85.5 MPa, even more preferably 81.0 MPa, and even more preferably 76.5 MPa.

[0044] The hardness [Hc1] of the opposing surface and the hardness [Hc2] of the surface layer of the cured sheet, obtained by curing this coating sheet at 160°C for 2 hours, can be controlled, for example, by the type of thermosetting resin (R), Mw, and functional group concentration. Furthermore, it can be adjusted by the type and amount of curable compound (C), and even the amount of filler added. As a method for increasing the hardness of the cured sheet, polyurethane resins and (meth)acrylic resins are suitable as the thermosetting resin (R). In addition, increasing the density of the three-dimensional network structure is effective, and this can be achieved by increasing the functional group concentration of the thermosetting resin (R), increasing the amount of curable compound (C) blended, or using a curable compound (C) with two or more functional groups.

[0045] From the viewpoint of suppressing warping of the coating layer covering electronic components, it is preferable that the ratio [E2c] / [E2], which is the ratio of the composite elastic modulus [E2c] of the surface layer of the cured sheet obtained by curing the coating sheet at 160°C for 2 hours to the composite elastic modulus [E2] of the surface layer of the coating sheet measured by nanoindentation, is 0.5 to 25.0. From the viewpoint of more effectively reducing warping, the upper limit of [E2c] / [E2] is more preferably 20.0, even more preferably 10.0, and even more preferably 5.0. The lower limit of [E2c] / [E2] is more preferably 0.6, even more preferably 0.7, and even more preferably 0.8.

[0046] The lower limit of the composite modulus [E2c] of the surface layer of the cured sheet obtained by curing the coating sheet at 160°C for 2 hours, as measured by nanoindentation, is preferably 16 MPa, more preferably 30 MPa, even more preferably 60 MPa, and even more preferably 120 MPa. The upper limit of the composite modulus [E2c] is preferably 2000 MPa, more preferably 1800 MPa, even more preferably 1600 MPa, and even more preferably 1400 MPa.

[0047] The lower limit of the composite modulus [E1c] of the opposing surface of the cured sheet obtained by curing the coating sheet at 160°C for 2 hours, as measured by the same method, is preferably 4 MPa, more preferably 6 MPa, even more preferably 8 MPa, and even more preferably 10 MPa. The upper limit of the composite modulus [E1c] is preferably 1600 MPa, more preferably 1400 MPa, even more preferably 1200 MPa, and even more preferably 1000 MPa.

[0048] The composite modulus [Ec1] of the opposing surface and the composite modulus [Ec2] of the surface layer of the cured sheet, obtained by curing this coating sheet at 160°C for 2 hours, can be controlled, for example, by the type of thermosetting resin (R), the weight-average molecular weight Mw, and the functional group concentration. Furthermore, it can be adjusted by the type and amount of curable compound (C), and even the amount of filler added. Furthermore, the [E2c] / [E2] ratio can be controlled to 0.5 to 25.0 by using a functional group concentration of 10 to 550 mmol / kg for the thermosetting resin (R) and controlling the crosslinking density. Methods for increasing the composite elastic modulus of the cured sheet include preparation methods similar to those used to increase the composite elastic modulus of the original coating sheet before curing. Furthermore, forming a structure with a high concentration of aromatic rings in the three-dimensional network structure tends to increase the composite elastic modulus.

[0049] The thickness of this coating sheet can be designed as appropriate depending on the application. For applications where thinness is required, the thickness of this coating sheet covering the top and sides of electronic components is preferably 5 to 500 μm, more preferably 10 to 300 μm, and even more preferably 15 to 250 μm.

[0050] As mentioned above, this covering sheet is composed of an insulating layer. The surface resistance of the insulating layer is 1.0 × 10⁻⁶. 7 It is preferable that the ratio be Ω / □ or greater, and 1.0 × 10 8 It is more preferable that the ratio is Ω / □ or greater, and 1.0 × 10 9 It is even more preferable that the ratio is Ω / □ or greater.

[0051] This coating sheet contains a binder component that forms the base of the coating layer. Examples of the binder component include thermosetting resins (R), and in addition to self-crosslinking thermosetting resins (R), thermosetting resins (R) that can react with curable compounds (C) are also preferred. Combinations of these are also possible. In particular, a combination of a thermosetting resin (R) and a curable compound (C) as the binder component is preferred. When using a curable compound (C), a thermosetting resin (R) having a reactive functional group and capable of reacting with the curable compound (C) is preferred.

[0052] [Thermosetting resin (R)] The weight-average molecular weight (Mw) of the thermosetting resin (R) is not limited, but is preferably between 10,000 and 2,000,000. The lower limit of Mw is more preferably 20,000, even more preferably 25,000, and even more preferably 30,000. The upper limit of Mw is more preferably 1,500,000, even more preferably 1,200,000, and even more preferably 1,000,000 and 900,000. By setting the Mw of the thermosetting resin (R) to 2,000,000 or less, the entanglement of molecular chains becomes easier to untangle when the coating sheet is applied, improving embedding performance. By setting the Mw of the thermosetting resin (R) to 10,000 or more, the coating strength of the coating sheet can be increased.

[0053] The thermosetting resin (R) can be used alone or in combination of two or more types. The content of the thermosetting resin (R) is not limited, but is preferably 15 to 95% by mass based on the total amount (100% by mass) of the coating sheet. The lower limit of the content is more preferably 25%, 35%, 45%, and 50%, and even more preferably 60% and 70% by mass. The upper limit of the content is preferably 90% and 85%, and even more preferably 80% by mass. By setting the content of the thermosetting resin (R) in the coating sheet to 15% by mass or more, the film-forming properties of the coating sheet can be improved, and by setting it to 95% by mass or less, the embedding properties of the coating sheet can be improved.

[0054] Examples of reactive functional groups for the thermosetting resin (R) include phenolic hydroxyl groups, acid anhydride groups, methoxymethyl groups, carboxyl groups, amino groups, epoxy groups, oxetanyl groups, oxazoline groups, oxazine groups, aziridine groups, thiol groups, isocyanate groups, blocked isocyanate groups, blocked carboxyl groups, and silanol groups. Reactive functional groups may be used individually or in combination of two or more. From the viewpoint of improving pick-and-place suitability and coating properties for electronic components, among these, phenolic hydroxyl groups, carboxyl groups, aziridine groups, and epoxy groups are preferred as reactive functional groups.

[0055] From the viewpoint of improving pick-and-place suitability and excellent embedding and coating properties, the lower limit of the functional group concentration of the thermosetting resin (R) is preferably 10 mmol / kg or more, more preferably 50 mmol / kg or more, and even more preferably 100 mmol / kg or more. Furthermore, from the viewpoint of improving pick-and-place suitability and excellent embedding and coating properties, the upper limit of the functional group concentration of the thermosetting resin (R) is preferably 550 mmol / kg or less, more preferably 400 mmol / kg or less, and even more preferably 300 mmol / kg or less. The functional group concentration can be determined by the method described in the examples below.

[0056] The glass transition temperature (Tg) of the thermosetting resin (R) is not limited, but is preferably -30 to 80°C, more preferably -20 to 70°C, even more preferably -12 to 50°C, and most preferably 5 to 45°C. Setting the temperature to -30 to 80°C reduces residual stress after the pressing process, thus improving warpage.

[0057] Preferred examples of thermosetting resins (R) include polyurethane resins, polyurethane urea resins, phenoxy resins, (meth)acrylic resins, polyester resins, polyamide resins, epoxy resins, polystyrene resins, polycarbonate resins, polyamide-imide resins, polyesteramide resins, polyether ester resins, alkyd resins, polyimide resins, benzoxazine resins, amino resins, polylactic acid resins, oxazoline resins, silicone resins, and fluororesins. From the viewpoint of improving the covering and embedding properties of the coating sheet, among these, the thermosetting resins (R) that are preferred are polyurethane resins including polyurethane resins and polyurethane urea resins; and (meth)acrylic resins including (meth)acrylic acid esters, (meth)acrylic acid esters, (meth)acrylonitrile, and (meth)acrylamide.

[0058] a. Polyurethane resins Polyurethane resins are resins containing two or more urethane bonds in one molecule. Polyurethane resins can be obtained by reacting a polyisocyanate with a polyol. The polyisocyanate only needs to have two or more isocyanate groups in one molecule, and from the viewpoint of uniform dispersion of the coating sheet, diisocyanate or triisocyanate is preferred, with diisocyanate being more preferred. As the diisocyanate, it can be appropriately selected from known aliphatic diisocyanates such as hexamethylene diisocyanate or known aromatic diisocyanates such as benzene-1,3-diisocyanate. Alternatively, an isocyanate-terminated prepolymer obtained by reacting a polyol with an excess of polyisocyanate may be used as an intermediate for the urethane resin. The polyol can be any polyol having two or more hydroxyl groups in one molecule, and diols or triols are preferred, with diols being more preferred. As the diol, it can be appropriately selected from known aliphatic diols such as ethylene glycol or known aromatic diols such as benzenediol. In addition, prepolymers such as polyether polyols, polyester polyols, and polycarbonate polyols may be used.

[0059] The polyurethane resin may also be a polyurethane urea resin having urea bonds. Polyurethane urea resin can be synthesized, for example, by reacting a polyamine with a urethane resin having isocyanate groups at its terminals. Polyamines can be any polyamine having two or more amino groups in one molecule. From the viewpoint of dispersibility, diamines or triamines are preferred, and diamines are more preferred. As for diamines, they can be appropriately selected from known aliphatic diamines such as ethylenediamine and known aromatic diamines such as phenylenediamine.

[0060] Polyurethane resins preferably have reactive functional groups such as hydroxyl groups, carboxyl groups, and epoxy groups, and more preferably have carboxyl groups. Furthermore, polyurethane resins having urethane bonds and ester bonds, and polyurethane urea resins having urethane bonds, urea bonds, and ester bonds are more preferable from the viewpoint of improving the coverage of the coating layer and reducing warping. Polyurethane resins can be produced, for example, by the method described in the examples. Polyurethane resins having ester bonds can be obtained, for example, by synthesizing a polyester polyol by condensation reaction of a polyol and a polycarboxylic acid, and then reacting the obtained polyester polyol with a polyisocyanate. Polyurethane urea resins having ester bonds can be obtained, for example, by reacting the aforementioned polyester polyol with a polyisocyanate and then reacting it with a polyamine.

[0061] b. (Meth)acrylic resin (Meth)acrylic resins are preferably acrylic copolymers obtained by copolymerizing monomers containing (meth)acrylic acid ester monomers. Examples of preferred (meth)acrylic acid ester monomers include alkyl (meth)acrylic acid ester monomers. To introduce reactive functional groups into the (meth)acrylic resin, (meth)acrylic copolymers obtained by copolymerizing a functional group-containing monomer with a (meth)acrylic acid ester monomer are preferred.

[0062] Alkyl (meth)acrylate monomers are compounds obtained by esterifying (meth)acrylic acid and introducing an alkyl or cycloalkyl group, where the alkyl or cycloalkyl group may be a linear, branched, or cyclic saturated aliphatic hydrocarbon group. A saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms is preferred, and a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms is more preferred. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, and (meth)acrylic acid. Examples include decyl, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, 4-n-butylcyclohexyl (meth)acrylate, and isobornyl (meth)acrylate. Among these, methyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate are particularly preferred from the viewpoint of uniform dispersion of the coating sheet, and methyl (meth)acrylate and n-butyl (meth)acrylate are more preferred.

[0063] Examples of reactive functional groups in (meth)acrylic resins include carboxyl groups, hydroxyl groups, epoxy groups, and amino groups. A simple method for introducing reactive functional groups is to use functional group-containing monomers during polymerization. Specifically, it is preferable to polymerize (meth)acrylic resins using carboxyl group-containing monomers, hydroxyl group-containing monomers, epoxy group-containing monomers, and / or amino group-containing monomers. By including functional group-containing monomers, a tough coating layer can be obtained during the curing process of this coating sheet.

[0064] Examples of carboxyl group-containing monomers include (meth)acrylic acid, β-carboxyethyl (meth)acrylate, p-carboxybenzyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, and isocrotonic acid. Among these, (meth)acrylic acid is preferred from the viewpoint of improving coating properties on electronic components and substrates.

[0065] Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Among these, 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate are more preferred from the viewpoint of improving coating properties to electronic components and substrates.

[0066] Examples of amino group-containing monomers include monoalkylamino esters of (meth)acrylates such as monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, and monoethylaminopropyl (meth)acrylate.

[0067] Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, 2,3-epoxypropyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, 4,5-epoxypentyl (meth)acrylate, 5,6-epoxyhexyl (meth)acrylate, 6,7-epoxyheptyl acrylate, 6,7-epoxyheptyl (meth)acrylate, 10,11-epoxyundecyl (meth)acrylate, and 4-glycidylcyclohexyl (meth)acrylate.

[0068] The (meth)acrylic resin preferably contains a total of 0.1 to 20% by mass of structural units derived from functional group-containing monomers in 100% by mass of the monomers constituting the (meth)acrylic resin. By setting the (meth)acrylic resin within this range, the coating and embedding properties can be adjusted. It is preferable that the constituent units derived from carboxyl group-containing monomers are present in an amount of 0.1 to 10% by mass relative to 100% by mass of the monomers constituting the (meth)acrylic resin. Being within this range can improve coating and embedding properties. It is preferable that the constituent units derived from hydroxyl group-containing monomers are present in an amount of 0.1 to 10% by mass relative to 100% by mass of the monomers constituting the (meth)acrylic resin. Being within this range can improve coating and embedding properties.

[0069] The (meth)acrylic resin may contain structural units derived from alkyl (meth)acrylates and other monomers copolymerizable with functional group-containing monomers. Examples include monomers having alkylene oxy groups and other vinyl monomers. Examples include methoxyethyl acrylate, methoxydiethylene glycol acrylate, vinyl acetate, vinyl crotate, styrene, acrylonitrile, and acrylamide. The structural units derived from the other monomers are present in an amount of, for example, 0.1 to 20% by mass of 100% by mass of the monomers constituting the (meth)acrylic resin.

[0070] (Meth)acrylic resins are obtained by polymerizing the aforementioned (meth)acrylic monomer mixture. A polymerization initiator may be used during polymerization as needed. The amount of polymerization initiator is, for example, 0.01 to 10 parts by mass per 100 parts by mass of the monomer mixture. The polymerization method is not limited. For example, polymerization can be carried out by solution polymerization, bulk polymerization, emulsion polymerization, or suspension polymerization, and solution polymerization is preferred due to the ease of polymerization control. Examples of solvents used in solution polymerization include acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, toluene, xylene, anisole, cyclohexanone, and isopropyl alcohol. The polymerization temperature can be, for example, 60 to 120°C, and the polymerization time can be about 2 to 12 hours.

[0071] A radical polymerization initiator is preferred as the polymerization initiator. Suitable radical polymerization initiators include peroxides and azo compounds such as 2,2'-azobisisobutyronitrile (AIBN).

[0072] [Curable compound (C)] The curable compound (C) is a resin or compound having reactive functional groups and a weight-average molecular weight (Mw) of less than 10,000, and may be a low-molecular-weight compound. The curable compound (C) can be used alone or in combination of two or more types. It is preferable that the curable compound (C) has functional groups that can react with the thermosetting resin (R). Through curing treatment, the functional groups of the curable compound (C) thermally crosslink with reactive functional groups such as carboxyl groups and hydroxyl groups of the thermosetting resin (R), thereby obtaining a crosslinked structure.

[0073] The curable compound (C) preferably has multiple of the aforementioned functional groups. Examples of curable compound (C) include epoxy compounds, isocyanate compounds, polycarbodiimide compounds, aziridine compounds, imidazole 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. Among these, epoxy compounds, phenolic compounds, organometallic compounds, imidazole compounds, and aziridines are preferred.

[0074] From the viewpoint of achieving both covering and embedding properties, a combination of a curable compound (C1) consisting of one or more selected from epoxy compounds (Ca) and phenol compounds (Cb) and one or more curable compounds (C2) selected from aziridine compounds (Cc) and imidazole compounds (Cd) is preferred. By using curable compound (C2), the curing reaction before the curing process can be promoted to some extent, and breakage of the coating sheet when it is stretched during coating of electronic components can be effectively prevented. On the other hand, by combining curable compound (C2) with curable compound (C1), it is effective in promoting the curing reaction before the curing process to some extent, and it is expected that the pot life of the product can be extended. Furthermore, since the residue of unreacted curable compound (C) can be suppressed in the curing reaction after coating electronic components, the heat resistance of the cured sheet can be effectively expressed. From the viewpoint of increasing adhesion after curing, curable compound (C1) preferably has at least one of an epoxy group and a hydroxyl group, and the combination of epoxy group and hydroxyl group is more preferable.

[0075] The epoxy compound (Ca) is not limited, but epoxy compounds having an N atom, such as glycidylamine, or epoxy compounds having a hydroxyl group are preferred. The number of functional groups in the epoxy group is preferably two or more. The epoxy equivalent of the epoxy compound (Ca) is not limited, but from the viewpoint of heat resistance, 100 to 1000 g / eq is preferred, and 150 to 500 g / eq is more preferred.

[0076] Examples of glycidylamines include N-glycidyl compounds obtained by the reaction of 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-xylenediamine are also suitable. Examples of commercially available products include SumiEpoxy ELM-100 and ELM-120 (both trade names, manufactured by Sumitomo Chemical Co., Ltd.), MY721 (trade name, manufactured by Ciba Specialty Chemicals), TETRAD-X and TETRAD-C (trade names from Mitsubishi Gas Chemical Co., Ltd.), and GAN (trade name from Nippon Kayaku Co., Ltd.).

[0077] Examples of difunctional epoxy compounds include bisphenol 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 fluoroorange diglycidyl ether, tetramethylbisphenol A diglycidyl ether, tetramethylbisphenol F diglycidyl ether, tetra-t-butylbisphenol A diglycidyl ether, and tetramethylbisphenol S diglycidyl ether; biphenol diglycidyl ethers such as biphenol diglycidyl ether, tetramethylbiphenol diglycidyl ether, dimethylbiphenol diglycidyl ether, and tetra-t-butylbiphenol diglycidyl ether; hydroquinone diglycidyl ether, dihydroquinone diglycidyl ether, and dihydroquinone diglycidyl ether. Benzene diglycidyl ethers such as dianthracene diglycidyl ether, methyl hydroquinone diglycidyl ether, dibutyl hydroquinone diglycidyl ether, resorcinol diglycidyl ether, and methyl resorcinol diglycidyl ether; aromatic diglycidyl ethers such as dihydroanthrahydroquinone diglycidyl ether, dihydroxydiphenyl ether diglycidyl ether, thiodiphenol diglycidyl ether, and dihydroxynaphthalene diglycidyl ether; Epoxy compounds obtained by adding hydrogen to the aromatic ring of diglycidyl ethers selected from bisphenol-based diglycidyl ethers, biphenol-based diglycidyl ethers, benzenediol-based 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 epihalohydrins;Examples include (poly)alkylene glycol diglycidyl ethers consisting solely of chain structures, 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 cyclic structures, such as 1,4-cyclohexanedimethanol diglycidyl ether. Examples of commercially available products include DIC's EPICLON 830, 840, 850, 860, 1050, 2050, 3050, 4050, 7050, HM-091, 101; Nagase ChemteX's Denacol EX-211, 212, 252, 711, 721; and Mitsubishi Chemical's jER1001.

[0078] As the epoxy compound (Ca), from the viewpoint of improving coating properties to electronic components, an epoxy compound that is liquid at 25°C or an epoxy compound having a softening point of 100°C or lower is preferred. Specific examples include liquid bisphenol-type epoxy resins such as "jER1001" (epoxy equivalent 470 g / eq, solid, softening point 64°C) manufactured by Mitsubishi Chemical Corporation, "R140P" (epoxy equivalent 188 g / eq, liquid) manufactured by Mitsui Chemicals, "DER383, liquid" manufactured by Dow Chemical Corporation, and "Epicote #807, liquid" (epoxy equivalent 170 g / eq) manufactured by Japan Epoxy Resin Co., Ltd.

[0079] The phenol compound (Cb) is not limited, but examples include phenol-type novolac resins. Examples of phenol-type novolac resins include bisphenol A type novolac resin, bisphenol F type novolac resin, and bisphenol S type novolac resin. The hydroxyl group equivalent is not limited, but from the viewpoint of resistance to moist heat and adhesion, 80 to 500 g / eq is preferred, and 100 to 250 g / eq is more preferred.

[0080] Examples of commercially available phenolic compounds (Cb) include Phenolite TD-2090, Phenolite TD-2131 (manufactured by Dai Nippon Printing Co., Ltd.), Besmol CZ-256-A (manufactured by DIC Corporation), Shounol BRG-555, Shounol BRG-556 (manufactured by Showa Denko Corporation), and CGR-951 (manufactured by Showa Polymer Co., Ltd.).

[0081] The aziridine compound (Cc) is not limited to trifunctional aziridines such as trimethylolpropanetris(3-(2-methyl-1-aziridyl)propionic acid) ester, trimethylolpropanetris(3-(1-aziridyl)propionic acid) ester, pentaerythritoltris(3-(2-methyl-1-aziridyl)propionic acid) ester, pentaerythritoltris(3-(1-aziridyl)propionic acid) ester, dipentaerythritoltris(3-(1-aziridyl)propionic acid) ester and sorbitoltris(3-(1-aziridyl)propionic acid) ester; pentaerythritoltetrakis(3-(1- Examples of tetrafunctional aziridines include aziridyl (3-(1-aziridyl)propionic acid) ester, sorbitol tetrakis(3-(1-aziridyl)propionic acid) ester, and ditrimethylolpropane tetrakis(3-(1-aziridyl)propionic acid) ester; pentahylated aziridines include sorbitol pentakis(3-(1-aziridyl)propionic acid) ester and dipentaerythritol pentakis(3-(1-aziridyl)propionic acid) ester; and hexahylated aziridines include dipentaerythritol hexakis(3-(1-aziridyl)propionic acid) ester and sorbitol hexakis(3-(1-aziridyl)propionic acid) ester. A commercially available example is Chemitight PZ-33 (trade name, manufactured by Nippon Shokubai Co., Ltd.).

[0082] The imidazole compound (Cd) is not limited to, but examples include: Ajinomoto Fine Techno Co., Ltd.'s product names: Amicure PN-23, Amicure PN-23J, Amicure PN-31, Amicure PN-31J, Amicure PN-40, Amicure PN-40J, Amicure PN-50, Amicure PN-H; ADEKA Corporation's product names: Adeka Hardener EH3293S, Adeka Hardener EH3366S, Adeka Hardener EH4346S; Air Products Japan Co., Ltd.'s product name: Sanmide LH210, Shikoku Chemical Co., Ltd. Examples of products manufactured by Seikogyo Co., Ltd. include: Cureazole SIZ, Cureazole 2MZ-H, Cureazole C11Z-A, Cureazole C17Z, Cureazole C11Z, Cureazole 1.2DMZ, Cureazole 2E4MZ, Cureazole 2PZ, Cureazole 2PZ-PW, Cureazole 2MZ-A, Cureazole 2MA-OK, Cureazole 2PHZ, Cureazole 2P4MHZ, Cureazole 2MZ-CN, Cureazole C11Z-CN, Cureazole 2E4MZ-CN, Cureazole 2PZ-CN, etc.

[0083] Imidazole compounds (Cd) are effective in accelerating the curing reaction before the curing process to some extent, and imidazoles with low activity temperatures and low solvent solubility are preferred in order to maintain a long pot life of the product. Specific examples include the trade names "Cureazole C17Z" (activity temperature: 85°C), "Cureazole C11Z" (activity temperature: 90°C), and "Cureazole 2P4MZ" (activity temperature: 100°C). By using these imidazole compounds (Cd), the curing reaction before the curing process can be easily controlled, and adhesion and coating properties can be easily controlled.

[0084] The content of the curable compound (C1) is preferably 1 to 250 parts by mass, and more preferably 5 to 150 parts by mass, per 100 parts by mass of the thermosetting resin (R). The content of the curable compound (C2) is preferably 0.01 to 5 parts by mass, and more preferably 0.1 to 2 parts by mass, per 100 parts by mass of the thermosetting resin (R). The ratio of curable compound (C1) to curable compound (C2), (C1) / (C2), is preferably 5 to 500, and more preferably 10 to 200. By setting the content within the above range, a strong cross-linked structure is formed in the coating layer, excessive curing of the coating layer is easily suppressed, and the ability to conform to uneven shapes can be further improved. Furthermore, wrinkles and fractures at the edges of the coating layer can be effectively suppressed.

[0085] [Inorganic filler (F)] This coating sheet may contain an inorganic filler (F) as an optional component. From the viewpoint of improving embedding properties, the content of inorganic filler (F) (total content if two or more types are included) is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on the total amount of solids in this coating sheet. From the viewpoint of bringing out the properties of inorganic filler (F), the lower limit of its content is preferably 5% by mass, more preferably 10% by mass, and the lower limit may be 15%, 20%, or 25% by mass.

[0086] The shape of the inorganic filler (F) can be selected as appropriate. Examples include flake-shaped, needle-shaped, spherical, dendritic, and fibrous fillers. Fillers of different shapes may be used in combination. A preferred example is a combination of flake-shaped and spherical fillers.

[0087] Average particle size D of inorganic filler (F) 50 The average particle size D of the inorganic filler (F) is preferably 0.02 to 10 μm, more preferably 0.03 to 5 μm. Even more preferably 0.1 to 2 μm, and particularly preferably 0.2 to 1 μm. 50 This can be measured using a light scattering particle size analyzer such as the "Microtrac MT3000II" (product name; manufactured by Nikkiso Co., Ltd.).

[0088] Examples of inorganic fillers (F) include silica, alumina, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, tin oxide, zirconium oxide, magnesium hydroxide, barium sulfate, calcium carbonate, talc, kaolinite, mica, sericite, montmorrolinite, bentonite, magnesium carbonate base, boron nitride, aluminum nitride, titanium nitride, magnesium silicon nitride, silicon carbide, titania, glass, ceramics, and carbon. Among these, silica, alumina, titanium oxide, zinc oxide, calcium carbonate, titanium nitride, and carbon are preferred. Two or more inorganic fillers may be combined. A preferred combination is silica with one or more selected from carbon and titanium oxide.

[0089] The inorganic filler (F) may be surface-modified with a surface modifier from the viewpoint of improving dispersibility in the coated sheet. Examples of surface modifiers include organic acids, silane coupling agents, surfactants, titanium coupling agents, and metal impurities, and it is preferable that an organic acid is included. Inorganic filler (F) is preferably used after dispersion treatment. Dispersers used for mechanical crushing for dispersion treatment include ball mills, roll mills, sand mills, bead mills, and nanomizers. Among these, bead mills are preferred. Examples of commercially available bead mills include Super Mill, Sand Grinder, Agitator Mill, Glen Mill, Dyno Mill, Pearl Mill, and Cobol Mill (all are trade names).

[0090] [Other ingredients] The coating sheet may contain an inert thermoplastic resin (P). Examples of inert thermoplastic resins (P) 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. While not particularly limited, polyamide resins, polyurethane resins, polyester resins, polycarbonate resins, polyimide resins, liquid crystal polymers, and fluororesins are more preferred from the viewpoint of heat resistance.

[0091] The inclusion of a thermoplastic resin (P) improves wrinkles and tears during molding. The thermoplastic resin (P) content is preferably 50 parts by mass or less per 100 parts by mass of thermosetting resin (R).

[0092] Furthermore, the coating sheet may contain a tackifying resin to improve adhesion to the substrate. The tackifying resin is a component that supplementarily improves adhesive strength, has a weight-average molecular weight of less than 5,000, and is distinct from the thermoplastic resin and thermosetting resin (R) mentioned above. Examples of tackifying resins include rosin-based resins, terpene-based resins, alicyclic petroleum resins, and aromatic petroleum resins.

[0093] This coating sheet may contain a plasticizer. The plasticizer can improve wrinkles and tears during the molding process of the coating sheet. Examples of plasticizers include fatty acid esters, phthalate esters, aromatic polycarboxylic acid esters, and polyesters.

[0094] This coating sheet may further contain colorants, flame retardants, lubricants, anti-blocking agents, silane coupling agents, antistatic agents, 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, paraffins, higher fatty acids, fatty acid amides, aliphatic alcohols, metal soaps, and modified silicones. Examples of anti-blocking agents include calcium carbonate, silica, polymethylsilsesquiosan, and aluminum silicate salts. By adding an antistatic agent, the generation of static electricity with other components such as pick-and-place plate members can be suppressed.

[0095] <Method for manufacturing electronic component covering sheets> The method for manufacturing the coating sheet is not particularly limited, but one example is a method of coating a release sheet with a composition obtained by dispersing or dissolving materials such as a thermosetting resin (R) and a curable compound (C), which are binder components that form the coating layer, in a solvent. Examples of coating methods 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 multi-layered sheets, known methods such as lamination and lamination via an easy-to-use adhesive can be applied.

[0096] <Applications of electronic component covering sheets> This coating sheet is particularly suitable for coating electronic component mounting substrates, but it may also be used to coat other items to be coated. Electronic component mounting substrates using this coating sheet are preferably incorporated into electronic devices such as liquid crystal displays, touch panels, notebook PCs, mobile phones, smartphones, and tablet terminals. [Examples]

[0097] This disclosure will be further described in detail by examples. This disclosure is not limited by these examples. In the examples, "parts" means "parts by mass" and "%" means "percent mass".

[0098] A. Raw materials for electronic component coating sheets, etc. <Thermosetting resin (R)> [Thermosetting resin r2] a. Synthesis of polyester diols In a glass flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and vacuum equipment, 266 parts terephthalic acid, 30 parts adipic acid, 212 parts 3-methyl-1,5-pentanediol, and 25 parts ethylene glycol were charged and stirred while passing nitrogen gas through. The mixture was gradually heated under atmospheric pressure and reacted at 200-230°C for approximately 8 hours to obtain a liquid with an acid value of 43 mg KOH / g. Next, 0.01 parts tetra-n-butoxytitanium was charged, and after purging with nitrogen, the mixture was stirred at 180°C for 30 minutes under a sealed condition. Then, the mixture was reacted at 230°C and 5 mmHg for 2 hours to obtain a polyester diol with an acid value of 1.1 mg KOH / g, a hydroxyl value of 114.2 mg KOH / g, and a molecular weight of 982.

[0099] b. Synthesis of urethane prepolymers Next, 734 parts of the polyester diol, 23.9 parts of dimethylolpropionic acid, 219 parts of tolylene diisocyanate, and 242 parts of toluene were charged into a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube, and the mixture was reacted at 50°C under a nitrogen atmosphere for 8 hours. To this, 1200 parts of toluene was added to obtain a urethane prepolymer solution having isocyanate groups at the ends.

[0100] c. Synthesis of urethane polymers Next, the obtained urethane prepolymer solution was heated to 70°C, and while maintaining this temperature, a solution of 20.0 parts 1,3-diaminopropane, 600 parts 2-propanol, and 961 parts toluene was added dropwise over 1 hour. After the dropwise addition was complete, the reaction was continued at 70°C for a further 6 hours to obtain a polyurethane resin (thermosetting resin r2) with an Mw of 130,000, a carboxyl group functional group concentration of 178 mmol / kg, a Tg of 20°C, and a solids content of 25%.

[0101] [Thermosetting resin r1] In the synthesis of thermosetting resin r2, the amount of dimethylolpropionic acid used in "b. Synthesis of urethane prepolymer" was changed from 23.9 parts to 1.3 parts in order to adjust the carboxyl group functional group concentration. In addition, the amount of tolylene diisocyanate used was changed from 219 parts to 394 parts in order to adjust the Tg. Furthermore, in order to adjust the solid content, the amount of toluene used in "c. Synthesis of urethane polymer" was changed from 961 parts to 3200 parts. Except for these changes, the resin was synthesized in the same manner as thermosetting resin r2, and a polyurethane resin (thermosetting resin r1) with Mw of 250,000, carboxyl group functional group concentration of 10 mmol / kg, Tg of 10°C, and solid content of 18% was obtained.

[0102] [Thermosetting resin r5] In the synthesis of thermosetting resin r2, the amount of dimethylolpropionic acid used in "b. Synthesis of urethane prepolymer" was changed from 23.9 parts to 67.1 parts in order to adjust the carboxyl group functional concentration. In addition, the amount of tolylene diisocyanate used in "c. Synthesis of urethane polymer" was changed from 219 parts to 198 parts in order to adjust the Tg. Furthermore, the amount of toluene used was changed from 961 parts to 1800 parts in order to adjust the solid content. Except for these changes, the resin was synthesized in the same manner as thermosetting resin r2, and a polyurethane resin (thermosetting resin r5) with Mw of 110,000, carboxyl group functional concentration of 535 mmol / kg, Tg of 40°C, and solid content of 21% was obtained.

[0103] [Thermosetting resins r3, r4, and r6] The following acrylic thermosetting resins were prepared. • Thermosetting resin r3: Acrylic thermosetting resin "Teisan Resin SG-PS (product name)", Mw = 850,000, epoxy group functional group concentration = 210 mmol / kg, Tg = 12℃, manufactured by Nagase ChemteX Corporation. • Thermosetting resin r4: Acrylic thermosetting resin "PARACRON MD-2000 (product name)", Mw = 600,000, carboxyl group functional group concentration = 356 mmol / kg, Tg = -11℃, manufactured by Negami Kogyo Co., Ltd. • Thermosetting resin r6: Acrylic thermosetting resin "Acrit 8UA-366 (product name)", Mw=30,000, hydroxyl group concentration=570 mmol / kg, Tg=27℃, manufactured by Taisei Fine Chemical Co., Ltd.

[0104] <Thermoplastic resin (P)> In the synthesis of thermosetting resin r2, the same method was used as for thermosetting resin r2, except that dimethylolpropionic acid was not added. This yielded a polyurethane-based thermoplastic resin p1 that was free of functional groups, had an Mw of 135,000, a Tg of 10°C, and a solids content of 20% (functional group concentration was 0 mmol / g).

[0105] <Curable compound (C)> • Curable compound c1:2 functional epoxy compound "EP-4100E (product name)", liquid, epoxy equivalent 190 g / eq, manufactured by ADEKA Corporation. • Curable compound c2: Polyfunctional novolac epoxy compound "EPICLON N-660 (trade name)", solid form, softening temperature 64°C, epoxy equivalent 210 g / eq, manufactured by DIC Corporation. ·Curable compound c3:2 functional epoxy compound "EPICLON 1055 (product name)", solid, softening temperature 67℃, epoxy equivalent 475g / eq, hydroxyl group-containing, manufactured by DIC • Curing compound c4: Novolac-type phenol compound "DL-92 (trade name)", hydroxyl group equivalent 107 g / eq, manufactured by Meiwa Kasei Co., Ltd. • Curable compound c5: Imidazole compound "Cureazole C17Z (trade name)", manufactured by Shikoku Chemicals Co., Ltd.

[0106] <Filler (F)> · Filler f1: Carbon black "Mitsubishi Carbon Black #20 (product name)", D 50 = 50 nm, manufactured by Mitsubishi Chemical Corporation · Filler f2: Silica "FB-3SDC (product name)", D 50 = 3.1 μm, manufactured by DENKA Co., Ltd.

[0107] B. Measurement method <Weight-average molecular weight (Mw)> The Mw of thermosetting resins, etc. is the value in terms of polystyrene obtained by GPC (gel permeation chromatography) measurement. The measurement conditions are as follows. Apparatus: Shodex GPC System-21 (manufactured by Showa Denko KK) Column: A connected column formed by connecting in series one Shodex KF-802 (manufactured by Showa Denko KK), one Shodex KF-803L (manufactured by Showa Denko KK), and one Shodex KF-805L (manufactured by Showa Denko KK) Solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Temperature: 40 °C Sample concentration: 0.2% Sample injection volume: 100 μL

[0108] <Glass transition temperature (Tg)> The glass transition temperature (Tg) of resin (A), etc. was measured in accordance with JIS K7198 using a dynamic viscoelasticity measuring device DVA-200 (manufactured by IT Measurement & Control Co., Ltd.). For the measurement, a 50-μm-thick PET film coated with a silicone release agent was used as the release substrate. The resin was coated on this release substrate to a thickness of 20 μm using a doctor blade, dried at 100 °C for 2 minutes, and then the obtained sheet was cut into 0.5 cm × 3 cm, and the sample was prepared by peeling off the release substrate. The measurement was carried out in the tensile mode under the conditions of a strain of 0.08%, a frequency of 10 Hz, a temperature increase rate of 10 °C / min, and a temperature range of -50 to 300 °C, and the temperature at which the main dispersion peak of the loss tangent (tanδ) appears was taken as Tg.

[0109] <Functional group concentration> The functional group concentrations of the thermosetting resin (R) were determined by the following method. Specifically, acidic groups such as hydroxyl groups, phenolic hydroxyl groups, and carboxyl groups were measured in accordance with JIS K0070:1992, bases such as amino groups in accordance with JIS K7237:1995, and epoxy groups in accordance with JIS K7236:2001, using an automatic titrator GT-200 manufactured by Mitsubishi Chemical Analytical Corporation, and the functional group concentrations were determined by converting them to solid content.

[0110] <Acid value> The acid value (mgKOH / g) was determined by converting the measured value to solid content using a GT-200 automatic titrator manufactured by Mitsubishi Chemical Analytical Corporation, in accordance with the potentiometric titration method specified in JIS K0070. <Hydroxyl value> The hydroxyl value (mgKOH / g) was determined by converting the measured hydroxyl value to solid content using a GT-200 automatic titrator manufactured by Mitsubishi Chemical Analytical Corporation, in accordance with the potentiometric titration method specified in JIS K0070.

[0111] <Hardness measured by nanoindentation method> [Sample preparation] The electronic component coating sheets with release film obtained by the method described later were cut to a size of 5 mm x 5 mm, and the release film was peeled off to prepare the electronic component coating sheets. The cured electronic component coating sheets were prepared by curing the electronic component coating sheets with release film at 160°C for 2 hours, cutting them to a size of 5 mm x 5 mm, and peeling off the release film. Next, a 5 μm thick layer of epoxy adhesive "DEV-TUBD-S208" (manufactured by Devcon) was applied to a 1 mm thick "S1112" glass slide (manufactured by Matsunami Glass Industry Co., Ltd.). Immediately after application, the electronic component coating sheet was placed on top of the adhesive with the measurement surface facing upwards, and left for 20 minutes to allow the adhesive to harden and fix in place, thus becoming the measurement sample.

[0112] [Measurement conditions] Measurements were performed on the electronic component coating sheet using a nanoindata under the following conditions. • Nanoindenter: Bruker "TI Premier" ·Indenter: Berkovich (triangular pyramid type) • Measurement mode: Single press (displacement control) ·Measurement temperature: Room temperature (25℃) • Indentation depth: 2μm ·Load speed: 200nm / s ·Unloading speed: 2μm / s ·Holding time: 5s • Measurement location: Center of the covering sheet of the electronic component • Number of measurement points: 10 locations 〔evaluation〕 From the load-displacement curves obtained by measurement, the hardness [H1] of the surface of the electronic component coating sheet that contacts the electronic component, and the hardness [H2] of the surface of the electronic component coating sheet opposite to the contact surface were determined using the formula (1) below. Furthermore, the hardness of the surface of the hardened sheet (coating layer) after curing of the electronic component coating sheet that contacts the electronic component was defined as [H1c], and the hardness of both the surface and the surface of the same hardened sheet (coating layer) that contacts the electronic component was defined as [H2c], and these hardnesses were determined using the same method. Hardness H[MPa]=Pmax / Ac...(1) (Pmax: maximum load, Ac: projected contact area) Hardness was calculated using the arithmetic mean of the six points remaining after subtracting values ​​that deviated by more than 20% above or below the arithmetic mean of the ten points.

[0113] <Composite elastic modulus by nanoindentation method> A sample was prepared in the same manner as the hardness measurement using the nanoindentation method described above, and the measurement was performed in the same manner as the hardness measurement using the nanoindentation method described above.

[0114] From the load-displacement curves obtained by measurement, the composite elastic modulus [E1] of the surface of the electronic component coating sheet that is in contact with the electronic component, and the composite elastic modulus [E2] of the surface of the electronic component coating sheet opposite to the surface in contact with the electronic component were determined using the formula (2) below. In addition, the composite elastic modulus [E1c] of the surface of the electronic component coating sheet that is in contact with the electronic component after curing, and the composite elastic modulus [E2c] of the surface of the electronic component coating sheet that is in contact with the electronic component and the surface were determined using the same method. Combined modulus of elasticity E [MPa] = (S·π) 1 / 2 ) / (2·Ac 1 / 2 )···(2) (S: Slope of the tangent line at the maximum load of the unloading curve, Ac: Contact projected area) The composite modulus of elasticity was calculated using the arithmetic mean of the six points remaining after subtracting the values ​​that deviated by more than 20% above or below the arithmetic mean of the ten points.

[0115] C. Fabrication of electronic component covering sheets [Example 1] 100 parts of thermosetting resin r2 (solids), 15 parts of curable compound c1 (EX-212L), 1 part of curable compound c4 (H-4), 0.5 parts of curable compound c5 (C11Z), and 1.2 parts of filler f1 were weighed out and placed in a container. Toluene was then added to the container to achieve a non-volatile content concentration of 33% by mass, and the mixture was stirred with a disperser for 10 minutes to prepare the composition. This composition was coated onto a release film (Y) using a doctor blade to achieve a thickness of 80 μm after drying. Next, it was dried at 100°C for 4 minutes to obtain an electronic component coating sheet with a single-layer (first layer) release film. In this sheet, the side with the release film was designated as the surface that does not come into contact with the electronic component, and the opposite side was designated as the opposing surface that comes into contact with the electronic component. Furthermore, a release-treated polyethylene terephthalate film with a thickness of 50 μm was used as the release film (Y) (the same applies to the following examples, etc.).

[0116] [Examples 2-6, Comparative Examples 1-3] Using the same method as in Example 1, only the type and amount of composition were changed as shown in Table 1 to produce single-layer release film coated electronic component sheets corresponding to Examples 2-6 and Comparative Examples 1-3.

[0117] [Example 7] 100 parts of thermosetting resin r2 (solids), 15 parts of curable compound c1 (EP-4100E), 1 part of curable compound c4 (DL-92), 0.5 parts of curable compound c5 (C17Z), and 1.4 parts of filler f1 were weighed out and placed in a container. Toluene was then added to the container to achieve a non-volatile content concentration of 33% by mass, and the mixture was stirred with a disperser for 10 minutes to prepare composition A. Composition A was then coated onto a release film (Y1) using a doctor blade to achieve a thickness of 80 μm after drying. Next, it was dried at 100°C for 4 minutes to form the first layer on the release film, obtaining a single-layer (first layer) pre-electronic component coated sheet with a release film.

[0118] Next, 100 parts of thermosetting resin r2 (solids), 20 parts of curable compound c2 (EPICLON 1055), 2 parts of curable compound c5 (C17Z), 1.4 parts of filler f1, and 13.7 parts of filler f2 were weighed out and placed in a container. Then, toluene was added to the container so that the non-volatile content concentration was 33% by mass, and the mixture was stirred with a disperser for 10 minutes to prepare composition B. Composition B was then coated onto a release film (Y2) using a doctor blade so that the thickness after drying was 40 μm. Next, it was dried at 100°C for 4 minutes to form a second layer on the release film (Y2), obtaining a single-layer (second-layer) pre-electronic component coated sheet with a release film.

[0119] Next, the coated surfaces of the first layer of pre-electronic component coating sheet with release film and the second layer of pre-electronic component coating sheet with release film were bonded together, and thermal lamination was performed under the conditions of 90°C, 0.3 MPa, and 1 m / min to obtain a two-layer electronic component coating sheet with release film (release film / first layer / second layer / release film).

[0120] [Examples 8-15, Comparative Examples 4-6] Except for changing the types and amounts of each composition used to prepare the first and second layers, as shown in Tables 1A and 1B, a two-layer electronic component coating sheet with a release film (release film / first layer / second layer / release film) was obtained in the same manner as in Example 7.

[0121] Tables 1A and 1B show the ingredients and their proportions for each example and comparative example. [Table 1A] [Table 1B]

[0122] D. Rating The following evaluations were performed on the release film-attached electronic component coating sheets and electronic component mounting substrates of each example and comparative example.

[0123] D-1. Assessment of pick-and-place suitability The pick-and-place suitability of the electronic component coating sheets of each example and comparative example onto a test substrate was evaluated using the compact mounter "SMT-64RH" (manufactured by Okuhara Electric Co., Ltd.). As a test substrate, a substrate made of glass cloth epoxy FR-4 (length 80 mm, width 80 mm, height 0.25 mm) was prepared, on which 0603 multilayer ceramic capacitors (MLCCs) (length 0.6 mm, width 0.3 mm, height 0.37 mm) were arranged in a 5x5 array with a mounting interval of 1 mm. Hereinafter, this substrate will be referred to as test substrate (S). First, the electronic component coating sheets with release films for each example and comparative example were cut to 11 mm vertically and 18 mm horizontally, and the release films were peeled off. The single-layer electronic component coating sheets were placed with the peeled surface facing upwards, and the double-layer electronic component coating sheets were placed with the second layer facing upwards, on the stick base of the compact mounter, and the test substrate (S) was fixed to the work holder. Next, the center of the electronic component coating sheet was picked up using a nozzle head (tip dimensions: 7mm vertical, 14mm horizontal, number of suction holes: 6), and the picked electronic component coating sheet was then transported to the top of the test substrate (S). After that, the transported electronic component coating sheet was placed on the MLCC on the test substrate (S) and pressed down with a load of 500g to place it. The following evaluations were performed at each step (picking, transporting, and placing).

[0124] [Pick suitability] In the above evaluation of pick-and-place suitability, the picking process was performed 10 times, and the number of times the electronic component coating sheet was successfully picked up (number of successful picks) was evaluated according to the following criteria. +++: All times (10 times) (Excellent). ++: 6 or more times, 9 or less times (excellent). +: 3 or more times, 5 or less times (usable). NG: 2 times or less (Target not met).

[0125] [Placement suitability] In the pick-and-place suitability evaluation, the time required to press the electronic component coating sheet onto the MLCC on the test substrate (S) during the placing process was evaluated according to the following criteria. +++: Less than 30 seconds (Excellent). ++: 30 seconds or more but less than 60 seconds (excellent). +: 60 seconds or more but less than 120 seconds (usable). NG: 120 seconds or more, or failure to crimp (target not met).

[0126] [Suitable for transport] In evaluating the suitability of the pick-and-place system, the angle θ (see Figure 9) of the protruding edge of the electronic component covering sheet from the nozzle head during transport was evaluated according to the following criteria. +++: Less than 5° (excellent). ++: 5° or more, less than 15° (excellent). +: 15° or more, less than 60° (usable). NG: 60° or higher (Target not met).

[0127] D-2. Evaluation of Coverage 1 (Coverage by Pressurization Process) After performing the above-described pick-and-place suitability evaluation, the sample on which each example and comparative example's electronic component coating sheet was placed was laminated with the cushioning material "Opulan CR1040" (manufactured by Mitsui Chemicals ICT Materials Co., Ltd.). Next, a manual hydraulic press (manufactured by Imoto Seisakusho Co., Ltd.) was used to perform heat-pressing under the conditions of 100°C, 0.1 MPa, and 3 min. After the heat-pressing was completed, the cushioning material was peeled off by hand, and the substrate was heated at 160°C for 2 hours. Through these processes, an electronic component mounted substrate covered with a coating layer, which is the cured product of the electronic component coating sheet, was obtained. The obtained electronic component mounted substrate was evaluated as follows.

[0128] [Coverage between electronic components] The electronic component-mounted substrates of each example and comparative example were polished to form cross-sections in which the spaces between MLCCs could be observed. Next, the presence or absence of voids (air bubbles) between the test substrate and the coating layer in 10 locations in the central region of the 25 MLCCs arranged in an array was observed and evaluated according to the following criteria. An electron microscope (magnification 400x) was used to confirm the presence of voids. +++: No voids were generated (excellent). ++: Voids occur in 1-3 locations (excellent). +: Voids occur in 4-7 locations (usable). NG: Voids occurred in 8 or more locations (target not met).

[0129] [Coverage properties of electronic components] The coating properties of the coating layer on 25 MLCCs on the electronic component mounting substrate of each example and comparative example were observed using an electron microscope (magnification 400x), and the number of MLCCs with exposed edges or top surfaces was counted and evaluated according to the following criteria. +++: Number of exposed MLCCs is 0 (extremely good). ++: Number of exposed MLCCs is 1-3 (excellent). +: Number of exposed MLCCs is 4-9 (practical). NG: More than 10 exposed MLCCs (target not met).

[0130] [Dimensional stability] The vertical and horizontal dimensions of the electronic component coating sheet on the electronic component mounting substrate of each example and comparative example were measured, and the maximum dimensional difference was evaluated by comparing it with the electronic component coating sheet before coating (11 mm vertical, 18 mm horizontal) according to the following criteria. The evaluation method for the dimensional difference was calculated as a negative value if the dimensions after coating were smaller than the dimensions before coating, and a positive value if they were larger. +++: Absolute value of dimensional change is less than 1 mm (excellent) ++: The absolute value of the dimensional change is 1 mm or more and less than 2 mm (excellent). +: Absolute value of dimensional change is 2mm or more and less than 3mm (practical). NG: Dimensional change is 3mm or more in absolute value (target not met).

[0131] D-3. Evaluation of Coverage 2 (Coverage by non-pressurized process) After performing the above-described pick-and-place suitability evaluation, a cushioning material "Opulan CR1040" (manufactured by Mitsui Chemicals ICT Materials Co., Ltd.) was laminated onto a sample on which the electronic component coating sheets of each example and comparative example were placed on a test substrate (S). Next, the sample was placed in a constant temperature bath (manufactured by ESPEC Corporation) set to 140°C under atmospheric pressure, and the electronic component coating sheet was heated and melted for 30 minutes to coat the MLCC area of ​​the test substrate (S) with the coating layer. After that, it was heated at 160°C for 2 hours. Through these processes, an electronic component mounted substrate coated with a coating layer, which is the cured product of the electronic component coating sheet, was obtained. The obtained electronic component mounted substrate was evaluated using the same methods and evaluation criteria as described in D-2 above for [coverage between electronic components], [coverage of electronic components], and [dimensional stability].

[0132] D-4. Evaluation of the moisture heat resistance of the coating layer After cutting the electronic component coating sheets with release films for each example and comparative example to 30 mm in length and 30 mm in width, the release films were peeled off and heat-laminated onto a substrate (G1) made of glass cloth epoxy FR-4 (50 mm in length, 50 mm in width, 0.25 mm in thickness) at 90°C, 0.3 MPa, and 1 m / min, and then heated at 160°C for 2 hours. This resulted in obtaining an evaluation substrate (E1) coated with a coating layer, which is a cured sheet of the electronic component coating sheet. Subsequently, the evaluation substrate (E) was kept in a constant temperature chamber (manufactured by ESPEC Corporation) set to 85°C and 85% humidity for 500 hours, after which the substrate was removed. Then, 100 grid lines with a 1 mm spacing were created on the coating layer using a cross-cut guide in accordance with JIS K5600. Next, adhesive tape was firmly pressed onto the grid lines, and the end of the tape was peeled off in one swift motion at a 45° angle. The survival rate of the 100 grid lines remaining on the coating layer on the electronic components (cross-cut survival rate) was evaluated according to the following criteria. Cellotape (registered trademark, manufactured by Nichiban Corporation) was used as the adhesive tape. +++: 100 / 100 (Excellent). ++: 95 / 100~99 / 100 (Excellent). +:80 / 100~94 / 100 (usable). NG: Less than 80 / 100 (Target not met).

[0133] D-5. Warp After cutting the electronic component coating sheets with release film for each example and comparative example to 150 mm in length and 150 mm in width, the release film was peeled off and the sheets were heat-laminated onto a substrate (G2) made of glass cloth epoxy FR-4 (150 mm in length, 150 mm in width, 0.6 mm thick) at 90°C, 0.3 MPa, and 1 m / min, and then heated at 160°C for 2 hours. This resulted in obtaining an evaluation substrate (E2) coated with a coating layer, which is a cured sheet of the electronic component coating sheet. The obtained evaluation substrate (E2) was placed on a flat surface, and the maximum distance between the mounting surface and the edge of the substrate was measured, and the warp height was evaluated according to the following criteria. +++: Less than 2mm (excellent). ++: 2mm or more, less than 3mm (excellent). +: 3mm or more, less than 5mm (usable). NG: 5mm or more (Target not met).

[0134] The physical properties and evaluation results of each example and comparative example are shown in Table 2 below. [Table 2]

[0135] Electronic component coating sheets with a hardness ratio [H2] / [H1] greater than 50.00 or less than 1.00 were found to have issues with pick-and-place suitability during pick-and-place operations, as shown in Comparative Examples 1-6. Furthermore, electronic component coating sheets with a composite modulus [E1]+[E2] less than 10 MPa were found to have issues with transport suitability during pick-and-place operations, as shown in Comparative Examples 1-3.

[0136] On the other hand, the embodiment in which the hardness ratio [H2] / [H1] satisfies 50.00 to 1.00 was confirmed to have excellent pick-and-place suitability. Furthermore, the embodiment in which the composite modulus [E1]+[E2] satisfies 10 MPa had excellent transport suitability during pick-and-place. In addition, the laminated electronic component coating sheet shown in Example 9 was confirmed to be particularly excellent, with coating properties (pressurized), coating properties (unpressurized), moisture heat resistance, and warpage being +++.

[0137] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from the spirit of this disclosure. Furthermore, this disclosure may be implemented by combining the embodiments described above or examples thereof as appropriate. [Explanation of Symbols]

[0138] 1 circuit board 2 Electronic components 3 Covering layer 10 Electronic component covering sheets 11, 21, 31 First layer 22, 32 First layer 33 Third layer 15, 25, 35 Opposite surfaces 16, 26, 36 Surface surface 50 Carrier Film 51 Plates 61 Diamond indenter 101, 102 Electronic component mounted circuit board

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 ratio [H2] / [H1] of the hardness [H1] of the surface of the electronic component coating sheet opposite to the surface facing the electronic component, measured by nanoindentation, is 1.00 to 50.

00. The hardness [H1] of the opposing surface of the electronic component coating sheet, as measured by nanoindentation, is 0.2 MPa or more and 15.0 MPa or less. An electronic component coating sheet having a ratio [E2c] / [E2] of the composite elastic modulus [E2c] of the surface layer of a cured sheet obtained by curing the electronic component coating sheet at 160°C for 2 hours to the composite elastic modulus [E2] of the surface layer of the electronic component coating sheet, measured by nanoindentation, which is 1.2 to 25.

0.

2. The electronic component coating sheet according to claim 1, wherein the sum of the composite elastic modulus [E1] of the opposing surface of the electronic component coating sheet and the composite elastic modulus [E2] of the surface layer of the electronic component coating sheet, [E1] + [E2], measured by nanoindentation, is 10 MPa or more.

3. The electronic component coating sheet according to claim 1, wherein the composite elastic modulus [E2] of the surface layer of the electronic component coating sheet, as measured by nanoindentation, is 8 MPa or more.

4. The electronic component coating sheet according to claim 1, wherein the hardness [H2c] of the surface layer of the cured sheet obtained by curing the electronic component coating sheet at 160°C for 2 hours, as measured by nanoindentation, is 1.0 MPa or more.

5. The electronic component coating sheet according to claim 1, comprising a thermosetting resin (A) having a functional group concentration of 10 to 550 mmol / kg.

6. 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, wherein the coating layer is formed from a cured product of an electronic component coating sheet according to any one of claims 1 to 5.

7. 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 step of placing the electronic component covering sheet according to any one of claims 1 to 5 on the substrate on which the electronic component is mounted, A step of forming the coating layer that covers the electronic component and at least a portion of the substrate using the electronic component coating sheet, A method for manufacturing an electronic component mounting substrate, comprising a step of curing the aforementioned coating layer.

8. The method for manufacturing an electronic component mounting substrate according to claim 7, wherein the step of forming the coating layer is performed without pressure or while applying pressure.

Images