Resin sheet, laminated sheet, semiconductor device, and method for producing the same

Abstract

To provide a resin sheet, a laminated sheet, a semiconductor device, and a method for producing the same that achieve superior productivity, allow excellent coatability even in cases where a plurality of semiconductor elements are covered collectively, and exhibit high reliability.SOLUTION: A resin sheet 12 for semiconductor sealing comprises a thermosetting composition containing a resin (A) and a crosslinking agent (B), the resin sheet 12 having an elongation at break of 10-400% at 23°C after being heated at 150°C for 1 hour, the resin sheet 12 having a relative permittivity of 3 or less at a frequency of 10 GHz and 23°C after being heated at 150°C for 1 hour, and also having a dielectric loss tangent of 0.01 or less at a frequency of 10 GHz and 23°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a resin sheet, a laminate sheet, a semiconductor device, and a method for manufacturing the same. [Background technology]

[0002] The sealing layer protects electronic components from physical impacts, temperature changes, etc. The formation of the sealing layer is gradually being replaced by a heat-melting resin sheet instead of the conventional conformal coating. For example, Patent Document 1 discloses a method for encapsulating electronic components by covering electronic components mounted on a substrate with a sheet made of a thermosetting composition and then heat-curing the composition. Patent Document 2 discloses a method for manufacturing an encapsulating film having an insulating layer and an electromagnetic wave shielding layer. The encapsulating film has an elongation percentage of 150 to 3500% at its softening point and is provided with concaves and convexes corresponding to the concaves and convexes formed on the electronic component-mounted substrate. Patent Document 3 discloses a method for manufacturing a semiconductor device, including the steps of temporarily attaching an encapsulating film to a semiconductor chip formed on a mounting substrate and heating and pressurizing the film in a reduced pressure environment to embed the semiconductor chip in a resin composition layer, and curing the resin composition layer to encapsulate the semiconductor chip and obtain a cured product. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-054363 [Patent Document 2] Japanese Patent Application Publication No. 2019-021757 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-29958 Summary of the Invention [Problem to be solved by the invention]

[0004] The method of Patent Document 3 allows for simultaneous coating using a sealing film, thereby improving versatility and productivity. However, there are problems with productivity, such as the need to form via holes that penetrate from the top surface of the cured body to the connecting wiring using a laser after forming the cured body of the sealing film (see Figures 8 to 10 in the same document).

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide a resin sheet, a laminated sheet, a semiconductor device, and a method for manufacturing the same, which are highly productive, have excellent coverage even when multiple semiconductor elements are collectively covered, and are capable of forming a highly reliable sealing layer. [Means for solving the problem]

[0006] As a result of extensive research, the present inventors have found that the problems of the present disclosure can be solved in the following aspects, and have thus completed the present disclosure. [1]: A resin sheet for semiconductor encapsulation for forming an encapsulation layer of a semiconductor element, the resin sheet is a thermosetting composition containing a resin (A) and a crosslinking agent (B), the resin sheet has an elongation at break of 10 to 400% at 23°C after being heated at 150°C for 1 hour; A resin sheet for semiconductor encapsulation, wherein the resin sheet has a relative dielectric constant of 3 or less at a frequency of 10 GHz and 23°C after heating at 150°C for 1 hour, and a dielectric dissipation factor of 0.01 or less at a frequency of 10 GHz and 23°C. [2]: The resin sheet for semiconductor encapsulation according to [1], wherein the resin sheet is sandwiched between two 50 μm PPS (polyphenylene sulfide) substrates, thermocompressed at 5 MPa and 80°C, then heat-treated at 150°C for 1 hour, and then subjected to a 2-week wet heat test at 121°C and 100% humidity. When a peel test is performed between one of the PPS substrates and the resin sheet at a peel angle of 90° and a peel speed of 300 mm / min, at least a portion of the material breaks. [3]: Resin (A) is The resin sheet for semiconductor encapsulation according to [1] or [2], comprising a urethane-based resin (A1) that contains a structural unit derived from at least one polyol selected from dimerdiol and trimertriol, and / or a structural unit derived from at least one polyamine selected from dimerdiamine and trimertriamine, and that has a urethane bond and may also have a urea bond. [4]: The resin sheet for semiconductor encapsulation according to [3], wherein the urethane resin (A1) has an acid value of 1 to 20 mgKOH / g. [5]: The resin sheet for semiconductor encapsulation according to [3] or [4], wherein the urethane resin (A1) has a weight average molecular weight of 50,000 to 200,000. [6]: The resin sheet for semiconductor encapsulation according to any one of [1] to [5], wherein the crosslinking agent (B) contains an epoxy compound. [7]: A laminated sheet obtained by laminating the resin sheet according to any one of [1] to [6] and one or more functional sheets. [8]: A semiconductor device comprising: a substrate; a semiconductor element mounted on the substrate; and an encapsulating layer that encapsulates the semiconductor element, wherein the encapsulating layer is formed from a cured product of the resin sheet according to any one of [1] to [6]. [9]: The semiconductor device according to [8], wherein the average thickness of the cured product is 10 to 300 μm.

[10] : A method for manufacturing a semiconductor device that collectively covers a plurality of semiconductor elements mounted on a substrate, a step of temporarily attaching the resin sheet according to any one of [1] to [6] to the side of the plurality of semiconductor elements; a step of softening the resin sheet by heating and / or pressurizing the resin sheet, and covering and bonding the upper surface of the substrate and the upper and side surfaces of the plurality of semiconductor elements; and curing the resin sheet to encapsulate the semiconductor element. [Effects of the Invention]

[0007] The present disclosure has the excellent effect of providing a resin sheet, a laminated sheet, a semiconductor device, and a manufacturing method thereof that are highly productive, have excellent coverage even when multiple semiconductor elements are collectively covered, and are highly reliable. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a laminate according to an embodiment of the present invention. [Figure 2] FIG. 10 is a schematic cross-sectional view showing an example of a laminate according to Modification 1. [Figure 3] FIG. 10 is a schematic cross-sectional view showing an example of a laminate according to Modification 2. [Figure 4] FIG. 11 is a schematic cross-sectional view showing an example of a laminate according to Modification 3. [Figure 5] 1A to 1C are cross-sectional views schematically showing an example of a manufacturing process for a semiconductor device according to an embodiment of the present invention. [Figure 6] 1A to 1C are cross-sectional views schematically showing an example of a manufacturing process for a semiconductor device according to an embodiment of the present invention. [Figure 7] 1A to 1C are cross-sectional views schematically showing an example of a manufacturing process for a semiconductor device according to an embodiment of the present invention. [Figure 8] 1A to 1C are cross-sectional views schematically showing an example of a manufacturing process for a semiconductor device according to an embodiment of the present invention. [Figure 9] 1A to 1C are cross-sectional views schematically showing an example of a manufacturing process for a semiconductor device according to an embodiment of the present invention. [Figure 10] 1A to 1C are cross-sectional views schematically showing an example of a manufacturing process for a semiconductor device according to an embodiment of the present invention. [Figure 11] FIG. 1 is a schematic cross-sectional view showing an example of a semiconductor device according to an embodiment of the present invention. [Figure 12] FIG. 2 is a schematic cross-sectional view of a test substrate according to the present embodiment. [Figure 13] FIG. 3 is a schematic cross-sectional view for explaining a method for evaluating coverage in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present disclosure will be described in detail below. Other embodiments are also included within the scope of the present disclosure as long as they are consistent with the spirit of the present disclosure. In this specification, a numerical range specified using "to" includes the numerical values ​​before and after "to" as the lower and upper limits. Unless otherwise noted, each component in this specification may be used independently, either alone or in combination of two or more types. The numerical values ​​described in this specification refer to values ​​obtained by the methods described in the Examples below, etc.

[0010] 1. Resin sheet The resin sheet of the present disclosure (hereinafter also referred to as the present resin sheet) is a sheet suitable for forming an encapsulating layer that encapsulates semiconductor elements (for semiconductor encapsulation). The present resin sheet has the advantage that it can encapsulate multiple semiconductor elements formed on a substrate or the like at once. Of course, the present resin sheet may also be used to encapsulate a single semiconductor element. The present resin sheet is a thermosetting composition containing a resin (A) and a crosslinking agent (B), and is converted into an encapsulating layer, which is a cured product, through an encapsulation process. The present resin sheet may be a single layer or multiple layers. In the case of multiple layers, it is formed by laminating layers of the same and / or different resin compositions.

[0011] Because the resin sheet has excellent flexibility, it is suitable for use in forming an encapsulating layer on an unencapsulated semiconductor element. Furthermore, because the resin sheet is lightweight, offers high design flexibility, and can be integrated into complex shapes, it is suitable for use in mounting multiple encapsulated semiconductor chips on a substrate and encapsulating them all at once. Furthermore, taking advantage of the low dielectric properties of the resin sheet, it may also be used to form a coating layer on electronic components, including semiconductor chips with encapsulated semiconductor elements (packaged ICs, etc.), for the purpose of insulating and protecting them in addition to encapsulation purposes.

[0012] In this specification, the term "semiconductor element" refers to power semiconductor elements such as IGBTs (insulated gate bipolar transistors), MOSFETs (metal oxide semiconductor field effect transistors), bipolar transistors, and diodes; light-emitting elements such as LEDs; optical semiconductor elements such as light-receiving elements; semiconductor integrated circuits formed on semiconductor substrates such as silicon substrates; and semiconductor chips obtained by dicing semiconductor integrated circuits formed on semiconductor substrates. As mentioned above, this resin sheet has excellent dielectric properties, is lightweight, can be integrated into complex shapes, and offers a high degree of design freedom, making it particularly suitable for use in the information and communications field. Semiconductor elements are typically formed or mounted on the top surface of a base substrate.

[0013] In the present disclosure, encapsulation refers to forming an encapsulating layer by using the present resin sheet to cover an object such as a semiconductor element (hereinafter, described as a semiconductor element) and curing the resin sheet. The encapsulating layer of the present disclosure includes all modes in which a semiconductor element is covered with an encapsulating layer, including modes in which the semiconductor element is directly encapsulated, as well as modes in which a semiconductor module or the like in which the semiconductor element is encapsulated is further encapsulated. Among these, the present resin sheet has low elasticity and excellent adhesion and stress relaxation, making it particularly suitable for use in modes in which substrates are encapsulated together while preventing warping.

[0014] It is important that the resin sheet has an elongation at break of 10 to 400% at 23°C after being heated at 150°C for 1 hour. Furthermore, it is important that the resin sheet has a relative permittivity of 3 or less at a frequency of 10 GHz and 23°C after being heated at 150°C for 1 hour, and a dielectric loss tangent of 0.01 or less at a frequency of 10 GHz and 23°C.

[0015] In the present disclosure, the elongation at break and dielectric properties were evaluated under conditions for a fully cured stage, i.e., the resin sheet was heat-treated at 150°C for 1 hour. The term "fully cured stage" may refer to a cured product as well as a product in the process of curing. In this specification, a cured product refers to a product that has been cured to the extent that further heating does not substantially promote the curing reaction, and the sealing layer is considered a cured product. The term "cured product" does not include a product that may undergo a partial curing reaction during the formation of the resin sheet but may be cured by further heating. The thermosetting composition may also be in a B-stage state, in which some of the components are semi-cured. A cured product of a thermosetting composition is generally obtained by heat-treating the composition at 100 to 180°C for 20 minutes to 2 hours.

[0016] By setting the elongation at break at 23°C after heating at 150°C for 1 hour to 10-400%, the resin sheet has excellent coverage over recesses formed by mounting semiconductor elements. More specifically, by setting the elongation at break at 23°C after heating at 150°C for 1 hour to 10% or more, the resin sheet can maintain an appropriate breaking strength while maintaining a moderate deformation force, thereby significantly reducing defects such as cracks and breaks in the encapsulating layer. By setting the elongation at break at 23°C after heating at 150°C for 1 hour to 400% or less, the resin sheet has excellent mechanical strength. As a result, cracks and breaks in the encapsulating layer, which can cause reduced reliability, can be significantly reduced.

[0017] The lower limit of the elongation at break is more preferably 100%, even more preferably 120%, and even more preferably 200%. The upper limit of the elongation at break is more preferably 390%, even more preferably 380%, and even more preferably 360%. If the resin sheet is anisotropic in elongation after heating at 150°C for 1 hour, the direction with the lowest elongation is 10% or more, and the direction with the highest elongation is 400% or less. The elongation at break refers to the permanent elongation after the resin sheet breaks when a tensile test is performed on the sheet at 23°C after heating at 150°C for 1 hour. This test was performed using the method described in the examples below, i.e., the method specified in JIS K7161:1994.

[0018] The breaking strength of this resin sheet at 23°C after heating at 150°C for 1 hour is preferably 10 to 60 MPa, more preferably 15 to 50 MPa, and even more preferably 20 to 45 MPa, from the viewpoint of increasing flexibility and improving coverage of uneven surfaces such as semiconductor elements.

[0019] The elongation at break of a resin sheet after heating at 150°C for 1 hour can be adjusted by the thickness of the resin sheet. The elongation at break tends to decrease as the thickness increases. The elongation at break can also be adjusted by the type of resin (A) in the resin sheet and the weight-average molecular weight (Mw) of the resin (A). The crosslink density of the sealing layer can also be adjusted to adjust the elongation at break at 23°C after heating at 150°C for 1 hour. Another suitable method for adjusting the elongation at break at 23°C after heating at 150°C for 1 hour is to adjust the number of functional groups and equivalent weight of the crosslinking agent (B) in the thermosetting composition used to form the resin sheet. The crosslinking agent (B) is preferably bifunctional or higher, and more preferably contains a trifunctional or tetrafunctional crosslinking agent (B). The crosslinking agent (B) can also be adjusted by the content of the crosslinking agent (B) in the composition. Furthermore, the type, amount, and particle size of the filler can also be adjusted. The flexibility can also be adjusted by the type of flexibility adjuster that does not contribute to crosslinking, such as a plasticizer, an inert resin that is not reactive per se, or an oligomer.

[0020] In high-frequency circuits, the transmission loss of electrical signals is significantly affected by dielectric loss. Dielectric loss increases in proportion to the product of the square root of the material's dielectric constant and its dielectric loss tangent. For this reason, insulating layers in contact with conductors require materials with low dielectric constants and dielectric loss tangents. Although the encapsulating material used to encapsulate semiconductor elements is not located in close proximity to the conductor, transmission loss can be effectively suppressed by using a material with excellent dielectric properties. Therefore, the resin sheet of the present disclosure is suitable for use in fifth-generation communication systems (5G) and next-generation communication systems (beyond 5G), etc.

[0021] The upper limit of the dielectric constant is more preferably 2.8, even more preferably 2.6, and even more preferably 2.5. The lower limit of the dielectric constant is not particularly limited, but is preferably 1.5 from the viewpoint of productivity. The upper limit of the dielectric loss tangent is more preferably 0.008, even more preferably 0.005, and even more preferably 0.004. The lower limit of the dielectric loss tangent is not particularly limited, but is preferably 0.0001 from the viewpoint of productivity.

[0022] The dielectric constant and dielectric loss tangent of the resin sheet after heating at 150°C for 1 hour can be adjusted by the type of resin (A), the number of polar groups in resin (A), the acid value, the acid value of the thermosetting composition, etc. The type and acid value of resin (A) will be described later.

[0023] The total content of the resin (A) and the crosslinking agent (B) in the present resin sheet (total mass) is preferably from 70 to 100 mass %, more preferably from 80 to 95 mass %.

[0024] The resin sheet preferably has a peel strength of 2 N / cm or more under the following measurement conditions. Specifically, the resin sheet is sandwiched between two 50 μm PPS substrates and thermocompression bonded at 5 MPa and 80°C. Heat treatment is then performed at 150°C for 1 hour. A two-week wet heat test is then performed at 121°C and 100% humidity. After these steps, a peel test is performed on the test piece between one PPS substrate and the resin sheet at a peel angle of 90° and a peel rate of 300 mm / min. The lower limit of the peel strength is more preferably 2.5 N / cm, even more preferably 3 N / cm, and even more preferably at least partial breakage. By achieving a peel strength of 2 N / cm or more, a resin sheet can be provided that provides a sealing layer with excellent mechanical properties.

[0025] The thickness of the resin sheet can be designed as appropriate. For example, the thickness of the resin sheet can be set to 1 to 1,000 μm. From the viewpoints of coverage and ease of handling, a thickness of 1 to 500 μm is preferred, 3 to 300 μm is more preferred, and 10 to 150 μm is even more preferred. By setting the thickness Ta of the resin sheet to 1 μm or more, the pressure during the pressing process is diffused within the resin sheet, thereby providing sufficient coverage. By setting the thickness of the resin sheet to 1,000 μm or less, the degree of design freedom can be increased. Furthermore, the resin sheet absorbs little pressure loss from the pressure applied during the pressing process, allowing the resin (A) and other components to flow sufficiently, thereby providing excellent coverage.

[0026] From the viewpoint of coating film strength, the Tg of the resin sheet after heating at 150°C for 1 hour is preferably 0 to 100°C. The lower limit of the Tg is more preferably 10°C, and even more preferably 15°C. The upper limit of the Tg is more preferably 80°C, and even more preferably 45°C.

[0027] From the viewpoint of coating properties, the tensile storage modulus of this resin sheet at 10 Hz and 25°C after heating at 150°C for 1 hour is 5 × 10 6 ~5×10 9 Preferably, it is 1×10 7 ~3×10 9 More preferably, it is 2×10 7 ~1×10 9Furthermore, it is more preferable that the tensile storage modulus of the resin sheet at 10 Hz and 150°C after heating at 150°C for 1 hour is 1×10 5 ~1×10 7 Preferably, it is 5 x 10 5 ~5×10 6 More preferably, it is 7×10 5 ~2×10 6 It is more preferable that:

[0028] From the viewpoint of achieving a balance between the handling property and heat resistance of the coating film, the Tan δ peak value at 23°C after heating the resin sheet at 150°C for 1 hour is preferably 0.3 to 1.2, more preferably 0.5 to 1.1, and even more preferably 0.6 to 1.0. The tensile storage modulus and Tan δ peak value can be adjusted by the type of resin (A) and the type and amount of crosslinking agent (B).

[0029] Liquid inks and the like have traditionally been used as sealing layers, but this poses productivity challenges. The sealing film of Patent Document 3 improves productivity by allowing the sealing layer to be filled into recesses between semiconductor chips all at once, but has the problem of being difficult to handle due to its high fluidity. When changing from a filling type like Patent Document 3 to a coating type, i.e., when the sealing layer is coated to conform to the shape of the semiconductor element, gaps are likely to form between the adherend and the coating layer at corners of unevenness formed by mounting the semiconductor element, particularly at right angles, and further gaps are likely to form over time, resulting in poor storage stability.

[0030] With this resin sheet, the encapsulating layer can be formed in one go to conform to the shape of the semiconductor element, thereby reducing material waste in the resin sheet. Furthermore, the ability to coat in one go significantly increases productivity and design freedom. Furthermore, since the resin sheet has a breaking elongation at 23°C after heating at 150°C for one hour within the above range, gaps that occur at corners (e.g., right-angled parts) between the adherend (e.g., semiconductor element) and the coating layer, which was previously difficult to achieve, are significantly improved, achieving excellent coating properties. After forming the encapsulating layer, other functional layers, such as a conductive layer, may be further coated. This method allows functional layers to be stacked using the same equipment, resulting in excellent productivity.

[0031] 1-1.Thermosetting composition The resin sheet is a thermosetting composition containing a resin (A) and a crosslinking agent (B). The crosslinking agent (B) preferably has two or more functional groups. At least one of the resin (A) and the crosslinking agent (B) contains a thermosetting component. A preferred embodiment is one in which the resin (A) and the crosslinking agent (B) are mutually cured by heat treatment. Note that the thermosetting component may be partially cured at the stage of the resin sheet.

[0032] 1-1a.Resin (A) Resin (A) functions as a binder to adhere and fix the adherend. Resin (A) is preferably a thermosetting resin, but thermoplastic resins, photocurable resins, and mixtures thereof may also be used. Thermosetting resins are resins that have multiple functional groups that can be used in crosslinking reactions by heating, and may also have self-crosslinkable functional groups.

[0033] The functional group of the thermosetting resin may be appropriately selected depending on the combination with the crosslinking agent (B) described below, and examples thereof include a hydroxyl group, a carboxyl group, an amino group, an epoxy group, an oxetanyl group, an oxazoline group, an oxazine group, an aziridine group, a thiol group, an isocyanate group, a blocked isocyanate group, and a silanol group. From the viewpoint of reactivity, the functional group is preferably a carboxyl group, a hydroxyl group, or an epoxy group.

[0034] The acid value of the thermosetting resin is preferably 1 to 30 mgKOH / g, more preferably 2 to 20 mgKOH / g, and even more preferably 3 to 15 mgKOH / g. By setting the acid value of resin (A) to 1 mgKOH / g or more, it is possible to optimize the crosslink density with crosslinking agent (B) while maintaining good intermolecular forces with adherends such as semiconductor elements, thereby improving sealing properties. Furthermore, by setting the acid value of resin (A) to 30 mgKOH / g or less, it is possible to improve adhesion while maintaining good intermolecular forces with adherends such as semiconductor elements.

[0035] The content of resin (A) in the present resin sheet (total mass) is preferably 50 to 99.5 mass%. Examples of resin (A) include amide resins, imide resins, (meth)acrylic resins, maleic acid resins, butadiene resins, urethane resins such as urethane resins and urethane urea resins, oxetane resins, phenoxy resins, polyamideimide resins, alkyd resins, amino resins, polylactic acid resins, oxazoline resins, benzoxazine resins, silicone resins, and fluororesins. Among these, resin (A) preferably contains a urethane resin including a urethane resin and / or a urethane urea resin.

[0036] The weight-average molecular weight (Mw) of the resin (A) can be appropriately designed, but is preferably 10,000 to 1,000,000 from the viewpoint of increasing the mechanical strength of the sealing layer and enhancing the storage stability of the resin sheet. From the viewpoint of durability and adhesion, it is more preferably 25,000 to 300,000, and even more preferably 50,000 to 200,000. The ratio (Mw / Mn) of the number-average molecular weight (Mn) to Mw, which indicates the degree of dispersion of the resin (A), is preferably 1 to 17, more preferably 5 to 14, and even more preferably 6.5 to 10. By setting the Mw / Mn to 1 to 17, it becomes easier to control the fluidity of the resin, improving coating properties. In addition, the rate at which the resin wets the adherend is made uniform, thereby improving adhesion.

[0037] The urethane resin can be designed appropriately and is not limited. However, a urethane resin (A1) containing a structural unit derived from at least one polyol selected from dimer diol and trimer triol, and / or a structural unit derived from at least one polyamine selected from dimer diamine and trimer triamine, and having a urethane bond and optionally a urea bond, is preferred. Hereinafter, structures derived from these structural units are collectively referred to as "dimer structures." The urethane bond is formed by the reaction of a hydroxy group with an isocyanate group, and the urea bond is formed by the reaction of an amino group with an isocyanate group. Urethane resins are obtained by urethane bonding between reaction components containing two or more polyol components per molecule and a polyisocyanate component having two or more isocyanate groups per molecule. Urethane urea resins are obtained, for example, by reacting a urethane prepolymer with terminal isocyanates, obtained by the reaction of a polyol with a polyisocyanate, with a chain extender such as a polyamine component having two or more amino groups per molecule.

[0038] The use of a urethane resin (A1) that combines a dimer structure with a urethane bond or a urethane bond and a urea bond results in excellent flexibility and an appropriate elongation at break at 23°C after heat treatment of the resin sheet at 150°C for 1 hour, resulting in excellent sealing properties. Furthermore, the unshared electron pairs of the nitrogen atoms contained in the urethane bonds and other bonds are thought to prevent tearing and fracture of the sealing layer, thereby achieving not only excellent coating properties but also strong adhesive strength to the adherend.

[0039] Suitable examples of the urethane resin (A1) include a urethane resin (A1-1) having a dimer structure, a urethane bond, and no urea bond, and a urethane urea resin (A1-2) having a dimer structure and a urethane bond and a urea bond. The urethane resin (A1) can be used alone or in combination of two or more. The use of the urethane resin (A1) can achieve both excellent sealing properties for semiconductor elements and adhesion and bonding properties to various adherends. Another advantage is that the biomass content can be increased.

[0040] Dimer diols and trimer triols can be obtained by reducing the carboxy groups of dimer acids and trimer acids, respectively, to alcohols. Dimer diamines and trimer triamines can be obtained, for example, by amidating the carboxy groups of dimer acids and trimer acids, respectively, and then converting them to amines by Hofmann rearrangement. The carboxy groups of dimer acids can be converted to isocyanate groups by Curtius rearrangement, and dimer polyisocyanates containing at least dimer diisocyanates and trimer triisocyanates can be used to synthesize the urethane resin (A1).

[0041] Commercially available dimer diol products include, for example, "Pripol 2033" manufactured by Croda Japan.

[0042] Commercially available dimer diamine products include, for example, "Priamine 1071," "Priamine 1073," "Priamine 1074," and "Priamine 1075" manufactured by Croda Japan, and "Versamine 551" and "Versamine 552" manufactured by BASF Japan.

[0043] The proportion of the monomer having a dimer structure used in the polymerization of the urethane resin (A1) is preferably 25 to 100% by mass per 100% by mass of all monomers used in the synthesis. By setting the proportion at 25% by mass or more, the covering ability to conform to the irregularities between multiple semiconductor elements can be improved. The lower limit is more preferably 40% by mass, and even more preferably 50% by mass. The upper limit is more preferably 90% by mass, and even more preferably 70% by mass. The proportion of the structural unit having a dimer structure can be determined from the content (% by mass) of the monomer having a dimer structure among the raw material monomers used in synthesizing the urethane resin (A1) relative to 100% by mass of all monomers. Usually, the ratio of the monomers used in the synthesis is the same as the constituent ratio in the resin.

[0044] Dimer acids are produced primarily from unsaturated fatty acids (e.g., oleic acid and linolenic acid, both of which are C18 unsaturated fatty acids) derived from natural sources such as vegetable oils. They are liquid dibasic acids primarily composed of dicarboxylic acids, produced by dimerization, for example, by reacting double bonds together in the presence of a catalyst at temperatures above 200°C. Dimer acids do not have a single skeleton, but rather have multiple structures, resulting in the existence of several isomers. Dimer acids derived from C18 unsaturated fatty acids include, for example, monocyclic, aromatic, polycyclic, and linear types, as shown in (1) below. [ka]

[0045] Trimer acids are typically by-products of dimer acid production. Like dimer acids, trimer acids exist as isomers. Dimer acids are typically mixtures of dimer and trimer acids, and commercially available dimer polyols are typically mixtures containing dimer diols and trimer triols. Similarly, commercially available dimer diamines are typically mixtures containing dimer diamines and trimer triamines.

[0046] The unsaturated fatty acid is preferably a raw material having 10 to 30 carbon atoms, and more preferably an unsaturated fatty acid having 12 to 24 carbon atoms. Specific examples of unsaturated fatty acids include natural fatty acids such as soybean oil fatty acid, tall oil fatty acid, and rapeseed oil fatty acid, as well as oleic acid, linoleic acid, linolenic acid, and erucic acid, which are obtained by refining these fatty acids. The unsaturated bonds may be hydrogenated as needed to reduce the degree of unsaturation. Dimer polyamines and dimer polyols with reduced degrees of unsaturation are suitable in terms of oxidation resistance (particularly coloration at high temperatures) and suppression of gelation during synthesis. The urethane resin (A1) has a dimer structure derived from one or more types of monomers.

[0047] The urethane resin (A1) preferably has, in addition to a dimer structure, a structural unit derived from a monomer having an alicyclic structure (excluding structural units derived from a monomer having a dimer structure; hereinafter, also referred to as an alicyclic structure). By using a urethane resin (A1) that combines a dimer structure and an alicyclic structure, the adhesion of the sealing layer can be more effectively improved.

[0048] From the viewpoint of achieving better water resistance, it is preferable to contain 0 to 200 parts by mass of a monomer (m2) having an alicyclic structure (hereinafter also referred to as monomer (m2); monomers corresponding to monomer (m1) are not included in (m2)) relative to 100 parts by mass of a monomer (m1) having a dimer structure used in the synthesis of the urethane-based resin (A1) (hereinafter also referred to as monomer (m1)). The lower limit of the content is more preferably 25 parts by mass, even more preferably 40 parts by mass. The upper limit of the content is more preferably 130 parts by mass, even more preferably 80 parts by mass. The monomer (m2) is preferably a low-molecular-weight compound. The molecular weight is preferably 50 to 800, more preferably 100 to 250.

[0049] The type of monomer (m2) is not limited. When the monomer (m2) is a polyol, suitable examples include 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and mixtures thereof, 1,3-cyclohexanediol, 1,4-cyclohexanediol, and mixtures thereof, and hydrogenated bisphenol A. Among these, 1,4-cyclohexanedimethanol is preferred. In 100% by mass of the polyol used in the synthesis of the urethane resin (A1), the content of the dimer polyol is preferably 50 to 100% by mass, more preferably 60 to 99% by mass, and even more preferably 70 to 97% by mass.

[0050] Suitable examples of the monomer (m2) that is a polyisocyanate include hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, etc. These may be polymeric compounds such as trimers. Preferred examples of the monomer (m2) when it is a polyamine include isophoronediamine (IPDA), menthenediamine, norbornanediamine, tricyclodecanediamine, adamantanediamine, diaminocyclohexane, 1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-3,6-diethylcyclohexane, diaminodiethylmethylcyclohexane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (bis(4-amino-3-methylcyclohexyl)methane), 3,3',5,5'-tetramethyl-4,4'-diaminodicyclohexylmethane, and 4,4'-diaminodicyclohexylmethane. Among these, isophoronediamine is preferred.

[0051] The urethane resin (A1) preferably has, in addition to a dimer structure, a structural unit derived from a monomer having a polyolefin structure (excluding structural units derived from a monomer having a dimer structure). Hereinafter, this will also be referred to as a polyolefin structure. By using a urethane resin (A1) that combines a dimer structure and a polyolefin structure, the dielectric properties of the sealing layer can be more effectively improved. From the viewpoint of the balance between the flexibility and heat resistance of the coating film, the number average molecular weight of the monomer having a polyolefin structure is preferably 500 to 5,000, more preferably 1,000 to 3,000.

[0052] From the viewpoint of improving the dielectric properties, it is preferable to contain 0 to 100 parts by mass of a monomer (m3) having a polyolefin structure (hereinafter also referred to as monomer (m3). Monomers corresponding to monomers (m1) or (m2) are not included in (m3)) per 100 parts by mass of a monomer (m1) having a dimer structure used in the synthesis of the urethane-based resin (A1). The lower limit of the content is more preferably 1 part by mass, and even more preferably 2 parts by mass. The upper limit of the content is more preferably 70 parts by mass, and even more preferably 45 parts by mass.

[0053] The type of monomer (m3) is not limited. When the monomer (m3) is a polyol, a suitable example is a hydrogenated polyolefin. A suitable example of the hydrogenated polyolefin is polybutadiene polyol. Commercially available products can be used as they are. Examples of commercially available hydrogenated polybutadiene polyols include GI-1000, GI-2000, and GI-3000 (trade names manufactured by Nippon Soda Co., Ltd.), "R-45EPI" (trade name manufactured by Idemitsu Petrochemical Co., Ltd.), "Polytail H" (trade name manufactured by Mitsubishi Chemical Corporation), and "KRASOL HLBH-P2000" and "KRASOL HLBH-P3000" (trade names manufactured by Cray Valley Chemical Industries, Ltd.). The number-average molecular weight (Mn) of the hydrogenated polybutadiene polyol is 500 to 10,000 from the viewpoints of lamination suitability and tack reduction. The lower limit of Mn is more preferably 800, and even more preferably 1,000. The upper limit of the Mn is more preferably 5000, further preferably 3000, and even more preferably 2500. The larger the molecular weight of the polyolefin structure, the greater the effect of lowering the dielectric constant.

[0054] Furthermore, in order to adjust the acid value, it is preferable to use a diol having a carboxy group in the molecule as a monomer. Suitable examples include dimethylolpropionic acid (DMPA), dimethylolbutanoic acid (DMBA), N,N-bishydroxyethylglycine, and methyl 3-[bis(2-hydroxyethyl)amino]propionate. Among these, dimethylolpropionic acid and dimethylolbutanoic acid are preferred from the viewpoint of solubility in solvents. By using a diol having a carboxy group in the molecule, a carboxy group can be introduced into the urethane resin (A1-1) and the urethane urea resin (A1-2), which can impart crosslinkability with a crosslinking agent (B) having, for example, an epoxy group or a carbodiimide group.

[0055] Monomer components other than those listed above may be used without departing from the spirit of the present disclosure. Examples of suitable polyol components include aromatic polyols, polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone diols, polycarbonate polyols, polyacrylate polyols, polysiloxane polyols, polyisoprene polyols, and polybutadiene polyols. Other examples include polyamine components such as aromatic-containing aliphatic polyamines, aromatic polyamines, and polyamines having heterocyclic structures. Further examples include aromatic polyisocyanates, aliphatic polyisocyanates, trimers or polymers thereof, allophanate polyisocyanates, and biuret polyisocyanates. Among the above monomers, a monomer having an alicyclic structure is referred to as monomer (m2). Similarly, among the above monomers, a monomer having a polyolefin structure is referred to as monomer (m3). The same applies hereinafter.

[0056] From the viewpoint of achieving excellent resistance to moist heat, it is preferable that the composition does not contain a "polyester structure" such as polyester polyol, or a "polycarbonate structure" such as polycarbonate polyol.

[0057] Specific examples of other monomers in polyols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3,3,5-trimethylpentanediol, 2,4-diethyl-1,5-pentanediol, 1,12-octadecanediol, 1,2-alkanediol, 1,3-alkanediol, 1-monoglyceride, 2-monoglyceride, 1-monoglycerin ether, and 2-monoglycerin ether. Specific examples of other monomers in polyisocyanates include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4- Examples of suitable polyisocyanates include diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, dimeryl diisocyanate, m-tetramethylxylylene diisocyanate, 4,4-diphenylmethane diisocyanate, bis-chloromethyl-diphenylmethane-diisocyanate, and 2,6-diisocyanate-benzyl chloride. These may be trimers to form an isocyanurate ring structure. These polyisocyanates can be used alone or in combination of two or more. Among these, tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and isocyanurate derivatives of hexamethylene diisocyanate are preferred. Although specific examples of other monomers of polyamines are not particularly limited, diamines are preferred because of the ease of adjusting Mw. Specific examples include diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, pentamethylenediamine, and p-phenylenediamine, as well as diamines having hydroxyl groups such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. These polyamines can be used alone or in combination of two or more.

[0058] From the viewpoint of imparting coating hardness, it is preferable that the polyamine contains a structural unit derived from a trifunctional or higher polyfunctional polyamine. Specific examples of trifunctional or higher polyamines include diethylenetriamine, iminobispropylamine (IBPA, 3,3'-diaminodipropylamine), triethylenetetramine, N-(3-aminopropyl)butane-1,4-diamine (spermidine), 6,6-iminodihexylamine, 3,7-diazanonane-1,9-diamine, and N,N'-bis(3-aminopropyl)ethylenediamine. The polyfunctional polyamine preferably has three amino groups. Furthermore, it is preferable to use it in combination with a diamine. Other suitable polyamines include hexamethylenediamine, iminobispropylamine, and bisanilinefluorene.

[0059] Monoamines may also be added during the synthesis of the urethane urea resin (A1-2). Monoamines act as reaction terminators during the production of the urethane urea resin (A1-2), binding to the molecular terminals of the urethane urea resin (A1-2) and inhibiting further reaction. As the amount of monoamine used increases, the molecular weight of the urethane urea resin decreases, so the final molecular weight of the urethane urea resin (A1-2) can be adjusted by changing the ratio of the polyamine and monoamine used. Examples of monoamines include n-butylamine, di-n-butylamine (DnBA), n-propylamine, n-pentylamine, n-hexylamine, n-octylamine, benzylamine (BA), and dibenzylamine. Furthermore, by using a monoamine having a reactive functional group other than an amino group, a new reactive functional group can be introduced into the terminal of the urethane urea resin (A1-2). Examples of monoamines having a reactive functional group other than an amino group include monoamines having a phenolic hydroxyl group, monoamines having a non-phenolic hydroxyl group, and monoamines having a sulfanyl group (also called a mercapto group or thiol group). Examples of monoamines having a phenolic hydroxyl group include 2-aminophenol (2-AM), 3-aminophenol (3-AM), 4-aminophenol (4-AM), 2-(aminomethyl)phenol, acetaminophen, and 2-(butylamino)phenol. Examples of monoamines having a non-phenolic hydroxyl group include monoethanolamine, diethanolamine, aminopropanol, and aminobutanol. Examples of monoamines having a sulfanyl group include 4-aminothiol.

[0060] The content of the urethane resin (A1) is preferably 50 to 100 parts by mass, more preferably 70 to 99.9 parts by mass, and even more preferably 80 to 99 parts by mass, per 100 parts by mass of the resin (A), from the viewpoints of improving conformability to semiconductor elements having uneven shapes and preventing cracks and breakage.

[0061] The acid value of the urethane resin (A1) is preferably 1 to 30 mg / KOH, more preferably 3 to 20 mg / KOH, and even more preferably 5 to 15 mg / KOH, from the viewpoint of adjusting the relative dielectric constant and dielectric loss tangent of the resin sheet under the above conditions. The acid value of the urethane resin (A1) can be adjusted, for example, by the amount of a diol component having a carboxy group used as a chain extender.

[0062] Any reactive functional group can be introduced into the urethane resin (A1). Specific examples include a carboxy group, a phenolic hydroxyl group, a hydroxyl group (a hydroxyl group other than a phenolic hydroxyl group), and a sulfanyl group (also called a mercapto group or a thiol group). From the viewpoint of achieving a balance between adhesion and storage stability, a phenolic hydroxyl group and a hydroxyl group (a hydroxyl group other than a phenolic hydroxyl group) are preferred, and a phenolic hydroxyl group is more preferred.

[0063] The Mw of the urethane resin (A1), like the Mw of the resin (A), is preferably from 10,000 to 1,000,000, more preferably from 25,000 to 300,000, and even more preferably from 50,000 to 200,000. By setting the Mw of the urethane resin (A1) within the above range, the breaking elongation can be made appropriate, and cracks and breakage can be effectively prevented.

[0064] The Tg of the urethane resin (A1) is preferably −10 to 100° C., more preferably 0 to 70° C., and even more preferably 5 to 40° C. By setting the Tg of the urethane resin (A1) within the above range, the resin sheet has excellent flexibility and coating properties.

[0065] The amine value of the urethane resin (A1) is preferably 0.1 to 15 mgKOH / g, more preferably 0.5 to 10 mgKOH / g. By setting the amine value of the urethane resin (A1) within the above range, excellent dielectric properties are obtained.

[0066] The hydroxyl value of the urethane resin (A1) is preferably from 1 to 50 mgKOH / g, more preferably from 3 to 30 mgKOH / g. By setting the hydroxyl value of the urethane resin (A1) within the above range, excellent dielectric properties are obtained.

[0067] The method for producing the urethane resin (A1) is not particularly limited, and it can be produced by a known method. The urethane resin (A1-1) can be obtained, for example, by reacting a polyol and a polyisocyanate. The urethane urea resin (A1-2) can be obtained, for example, by reacting a urethane prepolymer having a terminal isocyanate, which is composed of a polyol and a polyisocyanate, with a polyamine and, if necessary, a polymerization terminator. For example, there is a prepolymer method in which a polyol and a polyisocyanate are reacted (urethane-forming reaction) at a temperature of 50°C to 150°C, optionally using a solvent inert to isocyanate groups, and optionally using a urethane-forming catalyst, to produce a prepolymer having an isocyanate group at its terminal. This prepolymer is then reacted with a polyamine at 10°C to 60°C to obtain a urethane urea resin. In the synthesis of the urethane urea resin (A1-2), the ratio of the total molar number of amino groups in the polyamine to the molar number of isocyanate groups in the prepolymer is preferably 0.9 to 2.00, more preferably 0.95 to 1.1. Alternatively, a one-shot method is also suitable in which a high molecular weight polyol, a polyisocyanate, and a polyamine (and, if necessary, a polymerization terminator) are reacted in one step to obtain the urethane resin (A1). The polyamine may be used in the urethane reaction of the polyol and the polyisocyanate.

[0068] To introduce a dimer structure into the urethane resin (A1-1), a dimer polyol and / or a dimer diisocyanate is used.To introduce a dimer structure into the urethane urea resin (A1-2), a dimer polyol, a dimer diisocyanate, and / or a dimer polyamine is used.

[0069] From the viewpoint of imparting coating hardness, it is preferable to contain a structural unit derived from a trifunctional or higher polyfunctional polyamine. Furthermore, a polymerization terminator may be used for the purpose of adjusting Mw, etc. The polymerization terminator is not limited, but examples include monovalent active hydrogen compounds such as monoamine compounds having primary or secondary amino groups.

[0070] In producing the prepolymer of the urethane resin (A1-1) or the urethane urea resin (A1-2), the amounts of the polyol and polyisocyanate are preferably such that the NCO / OH ratio, which is the ratio of the number of moles of isocyanate groups in the polyisocyanate to the total number of moles of hydroxyl groups in the polymer polyol, is in the range of 1.0 to 3.0, more preferably 1.1 to 1.5.

[0071] In order to control the reaction, it is preferable to use an organic solvent in synthesizing the prepolymer of the urethane resin (A1-1) or the urethane urea resin (A1-2). The organic solvent is preferably an organic solvent inert to the isocyanate group, such as ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.); ethers (e.g., dioxane, tetrahydrofuran, etc.); and esters (e.g., ethyl acetate, butyl acetate, propyl acetate, etc.). These may be used alone or in combination of two or more.

[0072] Furthermore, a catalyst may be used in the synthesis of the prepolymer of the urethane resin (A1-1) or the urethane urea resin (A1-2). Examples of the catalyst include tertiary amine catalysts such as triethylamine and dimethylaniline, and metal catalysts such as tin and zinc. These catalysts are usually used in an amount of 0.001 to 1 mol % based on the polyol compound.

[0073] 1-1b. Crosslinking agent (B) The crosslinking agent (B) is a component that can be crosslinked by a curing treatment, and is preferably a component that can be cured by forming a three-dimensional crosslinked structure with the resin (A). The use of the crosslinking agent (B) causes a crosslinking reaction with the reactive functional groups of the resin (A) during heat pressing or heat aging in the pressing process, thereby strengthening adhesion to an adherend such as a semiconductor element. The crosslinking agent (B) preferably has a plurality of functional groups capable of reacting with the functional groups of the resin (A). Examples of the crosslinking agent (B) include known compounds such as silane coupling agents, epoxy compounds, acid anhydride group-containing compounds, imidazole compounds, isocyanate compounds, aziridine compounds, and amine compounds. From the viewpoint of adjusting the elongation at break at 23°C after the heat treatment of the resin sheet, silane coupling agents, epoxy compounds, aziridine compounds, imidazole compounds, and isocyanate compounds are preferred, and epoxy compounds are more preferred.

[0074] The epoxy compound is not particularly limited as long as it has an epoxy group in the molecule. For example, epoxy resins such as glycidyl ether epoxy resins, glycidyl amine epoxy resins, glycidyl ester epoxy resins, and alicyclic (cycloaliphatic) epoxy resins can be used. Polyfunctional epoxy resins with three or more functionalities are useful for improving the heat resistance and adhesion of the coating film, and bifunctional epoxy resins such as bisphenol A and bisphenol F are useful when flexibility of the coating film is required. Examples of glycidyl ether type epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AD ​​type epoxy resins, cresol novolac type epoxy resins, phenol novolac type epoxy resins, α-naphthol novolac type epoxy resins, bisphenol A type novolac type epoxy resins, dicyclopentadiene type epoxy resins, tetrabromobisphenol A type epoxy resins, brominated phenol novolac type epoxy resins, tris(glycidyloxyphenyl)methane, and tetrakis(glycidyloxyphenyl)ethane. Examples of glycidylamine type epoxy resins include tetraglycidyldiaminodiphenylmethane, triglycidyl paraaminophenol, triglycidyl meta-aminophenol, and tetraglycidyl meta-xylylenediamine. Examples of glycidyl ester type epoxy resins include diglycidyl phthalate, diglycidyl hexahydrophthalate, and diglycidyl tetrahydrophthalate. Examples of cycloaliphatic (alicyclic) epoxy resins include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate, or bis(epoxycyclohexyl)adipate. As the epoxy compound, one of the above compounds can be used alone, or two or more of them can be used in combination. As the epoxy compound, from the viewpoint of high adhesiveness and heat resistance, bisphenol A type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, tris(glycidyloxyphenyl)methane, or tetrakis(glycidyloxyphenyl)ethane is preferred. Examples of commercially available products include bisphenol A epoxy resins such as jER828, 1002, and 1004, trade names of Mitsubishi Chemical Corporation; novolac epoxy resins such as jER152 and 154, trade names of Mitsubishi Chemical Corporation and YDPN-638 and YDCN-700, trade names of Nippon Steel Chemical & Material Co., Ltd.; bisphenol F epoxy resins such as YDF-170 and YDF2001, trade names of Nippon Steel Chemical & Material Co., Ltd.; and multifunctional epoxy resins having three or more functional groups, such as JER1031S and 1032H60, trade names of Mitsubishi Chemical Corporation, TETRAD-X, trade name of Mitsubishi Gas Chemical Company, Inc., and TECHMORE VG3101L, trade name of Printec Co., Ltd.

[0075] The aziridine compound is not particularly limited as long as it contains an aziridine group in the molecule. For example, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxite), N,N'-toluene-2,4-bis(1-aziridinecarboxite), bisisophthaloyl-1-(2-methylaziridine), tri-1-aziridinylphosphine oxide, N,N'-hexamethylene-1,6-bis(1-aziridinecarboxite), trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, trimethylolpropane tris[3-(1-aziridinyl)propionate], trimethylolpropane tris[3-( 1-aziridinyl)butyrate], trimethylolpropane tris[3-(1-(2-methyl)aziridinyl)propionate], trimethylolpropane tris[3-(1-aziridinyl)-2-methylpropionate], 2,2'-bishydroxymethylbutanol tris[3-(1-aziridinyl)propionate], pentaerythritol tetra[3-(1-aziridinyl)propionate], diphenylmethane-4,4-bis-N,N'-ethyleneurea, 1,6-hexamethylene bis-N,N'-ethyleneurea, 2,4,6-(triethyleneimino)-Syn-triazine, bis[1-(2-ethyl)aziridinyl]benzene-1,3-carboxylic acid amide. Among these, 2,2'-bishydroxymethylbutanol tris[3-(1-aziridinyl)propionate] is preferred from the viewpoint of heat resistance.

[0076] Imidazole compounds include 2-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-dimethylimidazole, 2-phenylimidazole, imidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[ Examples of imidazole compounds include 2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole, as well as compounds with improved storage stability, such as imidazole compounds encapsulated in microcapsules. Among these, 2-phenylimidazole is preferred from the viewpoint of storage stability.

[0077] The isocyanate compound is not particularly limited as long as it has an isocyanate group in the molecule. In particular, hexamethylene diisocyanate trimer having an isocyanurate ring and blocked with MEK oxime or pyrazole is preferred from the viewpoint of heat resistance.

[0078] In the present disclosure, from the viewpoint of improving water-resistant insulation and coating properties, it is preferable to contain two or more types of crosslinking agents. Suitable examples include those containing two or more types selected from silane coupling agents, epoxy compounds, aziridine compounds, imidazole compounds, and isocyanate compounds. More suitable examples include those containing one or more types of silane coupling agents, epoxy compounds, aziridine compounds, imidazole compounds, and isocyanate compounds in combination with an epoxy compound of a different type from the epoxy compound. Among these, combinations containing two or more types selected from epoxy compounds, aziridine compounds, and imidazole compounds are more suitable.

[0079] The content of the crosslinking agent (B) (total content when two or more types are used in combination) is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 10% by mass, based on the total mass of the resin sheet. By setting the content within this range (0.01 to 30% by mass), compatibility with the resin (A) can be improved while the waterproof insulation properties and coating properties can be suitably adjusted. From the viewpoint of coating film strength, the content of the crosslinking agent (B) relative to the resin (A) is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 3 to 6.5 parts by mass, per 100 parts by mass of the resin (A).

[0080] 1-1c. Other ingredients Organic fillers such as resin beads and inorganic fillers such as metal oxides can be used as additives to adjust the elongation at break at 23°C after heating the resin sheet for 1 hour at 150°C. The amount of organic filler and / or inorganic filler added (the total content when both are used) is preferably 0.1 to 30% by mass, more preferably 0.3 to 15% by mass, and even more preferably 0.5 to 5% by mass, relative to 100% by mass of the total amount of the resin sheet.

[0081] Examples of additives for adjusting the breaking elongation include organic fillers such as poly(meth)acrylate beads, acrylic-styrene copolymer beads, polycarbonate beads, polyvinyl chloride beads, polytetrafluoroethylene powder, polyethylene powder, epoxy resin powder, polyamide powder, polyurethane powder, and polysiloxane powder, as well as polymer fillers such as multilayer core-shell fillers using silicone, acrylic, styrene-butadiene rubber, butadiene rubber, etc. Examples of inorganic fillers include inorganic compounds such as silica, alumina, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, talc, kaolinite, mica, basic magnesium carbonate, sericite, montmorolinite, kaolinite, bentonite, boron nitride, aluminum nitride, titanium nitride, and carbon black. Among these, from the viewpoint of coating film resistance to scratches, titanium oxide, titanium nitride, silica, talc, mica, kaolinite, or montmorillonite is preferred, and titanium oxide, titanium nitride, and silica are more preferred. In the present disclosure, from the viewpoint of coating film resistance, two or more types of inorganic fillers may be contained. Specifically, an example in which silica is contained in combination with one or more types selected from titanium oxide, titanium nitride, silica, talc, mica, kaolinite, or montmorillonite is preferred.

[0082] The average primary particle size (hereinafter referred to as particle size) of the inorganic filler is preferably 1 to 100 nm. By making the particle size 1 nm or more, it is easy to maintain the viscosity of the resin composition at a level suitable for coating. Furthermore, by making the particle size 100 nm or less, the coating film resistance is improved. The particle size of the inorganic filler can be determined from the average value of approximately 20 primary particles observed in an image magnified approximately 50,000 to 1,000,000 times using a transmission electron microscope (TEM).

[0083] The inorganic filler may be mechanically crushed and then mixed with the resin (A), and the mixture may then be further dispersed. A dispersant is preferably used for the dispersion treatment. The dispersant can impart repulsive forces between the inorganic fillers so that the inorganic fillers dispersed through the dispersion treatment described above do not re-aggregate. The dispersant may be a conventionally known compound. Examples include polymeric dispersants, pigment derivative dispersants, and surfactants selected from cationic, anionic, and nonionic surfactants. The Mw of these dispersants is, for example, about 1,000 to 30,000.

[0084] The resin sheet may contain a curing accelerator to adjust the crosslinking rate during the curing treatment or the physical properties of the resin sheet. The curing accelerator is not particularly limited and can be selected appropriately. Specific examples of the curing accelerator include amine-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. These may be used alone or in combination of two or more. From the viewpoint of coating suitability, the content of the curing accelerator is preferably 0.01 to 10 mass %, more preferably 0.1 to 5 mass %, based on the total amount (100 mass %) of the resin sheet.

[0085] The thermosetting composition of the present disclosure may further contain various additives within the scope of the present disclosure. Examples of such additives include thermally conductive fillers and electrically conductive fillers. Furthermore, additives such as antistatic agents, flame retardants, antioxidants, ultraviolet inhibitors, colorants, dispersants, surface conditioning additives, cure retarders, softeners, antiblocking agents, adhesion improvers, and embedding improvers may also be added as appropriate.

[0086] 2.Laminated sheet The laminate sheet of the present disclosure (also referred to as the present laminate sheet) is a sheet obtained by laminating the present resin sheet and one or more functional sheets. The functional sheet is not particularly limited. Specific examples of functional sheets include electromagnetic wave shielding sheets, thermally conductive sheets that dissipate heat from semiconductor elements, shielding sheets that prevent semiconductor elements from being seen or that block light, moisture-proof sheets that protect semiconductor elements from moisture, decorative sheets, flame-retardant sheets that have been imparted with flame retardancy, protective sheets that have been imparted with hard coating properties, bonding sheets that improve bonding to semiconductor elements, etc., and functional sheets that are any combination of these. A functional layer can be formed by coating the functional sheet of the present laminate sheet.

[0087] By using this laminate sheet, it is possible to form an encapsulating layer and a functional layer on a semiconductor element at the same time. The properties of the functional sheet in this laminate sheet can be designed as appropriate. Preferably, the functional sheet is a thermosetting composition containing a resin (A) and a crosslinking agent (B), and the functional sheet has an elongation at break of 10 to 400% at 23°C after heating at 150°C for 1 hour. More preferably, the laminate sheet is a thermosetting composition containing a resin (A) and a crosslinking agent (B), and the functional sheet has an elongation at break of 10 to 400% at 23°C after heating at 150°C for 1 hour.

[0088] It is more preferable that the present laminate sheet has a relative permittivity of 3 or less at a frequency of 10 GHz and 23°C after heating the functional sheet at 150°C for 1 hour, and a dielectric dissipation factor of 0.01 or less at a frequency of 10 GHz and 23°C. It is even more preferable that the present laminate sheet has a relative permittivity of 3 or less at a frequency of 10 GHz and 23°C after heating the functional sheet at 150°C for 1 hour, and a dielectric dissipation factor of 0.01 or less at a frequency of 10 GHz and 23°C.

[0089] When a thermally conductive sheet is used as the functional sheet, it is preferable to add a thermally conductive filler to the thermosetting composition of the resin sheet. When an electromagnetic wave shielding sheet is used as the functional sheet, a conductive filler may be added to the thermosetting composition of the resin sheet.

[0090] The thermally conductive filler may be a metal oxide, a metal nitride, a metal hydroxide, a metal carbonate, a metal silicate, a hydrated metal compound, crystalline silica, amorphous silica, silicon carbide, or a composite thereof. Examples of the conductive filler include a metal filler, a conductive ceramic filler, and a mixture thereof. Examples of the metal filler include metal powders such as gold, silver, copper, and nickel, alloy powders such as solder, and core-shell fillers such as silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. However, from the viewpoint of controlling the relative dielectric constant and dielectric loss tangent, the resin sheet preferably has a lower metal content.

[0091] From the viewpoint of coverage, the content of the inorganic filler (total content when two or more types are included) is preferably 0.01 to 20 mass% based on the total amount (100 mass%) of the functional sheet, with a lower limit of 0.1 mass% being more preferable and an upper limit of 15 mass%, more preferably 10 mass%, even more preferably 5 mass%. By including 0.01 to 20 mass% of the inorganic filler, the effect of increasing the fluidity of the functional sheet during the pressing process is more easily exhibited, improving coverage. Furthermore, from the viewpoint of controlling the dielectric properties, the lower the metal content of the functional sheet, the more preferable. The total amount of the conductive filler and the thermally conductive filler in 100 mass% of the inorganic filler is preferably 0 to 20 mass%, more preferably 0 to 15 mass%. Examples of metal oxides include conductive metal-containing compounds and insulating metal oxides, with insulating metal oxides being preferred.

[0092] 3.Laminate The laminate of the present disclosure is a laminate in which the resin sheet of the present disclosure is integrated with a material used in the manufacturing process or until the time of manufacturing, or a laminate in which the laminate sheet of the present disclosure is integrated with a material used in the manufacturing process. Examples of such materials include cushioning materials and protective sheets. In the manufacturing method of the present semiconductor device, use of the present laminate can simplify the manufacturing process.

[0093] As described below, the use of the present laminate is not essential for the manufacture of the semiconductor device of the present disclosure, and the present resin sheet or the present laminate sheet may be used alone. Also, the present resin sheet and the above-mentioned cushioning material, which is not integrated with the present resin sheet, may be overlaid during the manufacturing process to form a blanket coating. Alternatively, the present resin sheet may be coated to form an encapsulating layer, and then a functional sheet may be coated to form a functional layer. Furthermore, a manufacturing process sheet, such as a cushioning material or a protective sheet, may be overlaid on the present resin sheet or the present laminate sheet to form an encapsulating layer.

[0094] The deeper the recesses and protrusions of the semiconductor elements to be encapsulated are, and the shorter the distance between the semiconductor elements is, the lower the encapsulation performance tends to be. However, the use of a cushioning material is expected to more effectively enhance the covering properties and flexibility of the resin sheet and the laminate sheet. Furthermore, by protecting the resin sheet and the laminate sheet with a protective sheet, the intrusion of dust and other particles into the encapsulation layer can be effectively prevented. From the viewpoint of workability, a release liner is preferable as the protective sheet. Furthermore, a protective sheet may be placed on the cushioning material to prevent the cushioning material from adhering to parts of the manufacturing equipment when softened.

[0095] Examples of release liners include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; plastic films such as polyolefin films such as polypropylene and polyethylene; and plastic sheets coated with a release agent such as silicone resin to provide a release layer. There are no particular restrictions on the thickness of the release liner, but it is usually about 10 to 200 μm.

[0096] A schematic cross-sectional view showing an example of the present laminate is shown in Figure 1. As shown in the figure, laminate 1 is a laminate in which resin sheet 12 is sandwiched between first release liner 11 and second release liner 13.

[0097] FIG. 2 is a schematic cross-sectional view showing an example of a laminate according to Variation 1 of the present disclosure. This laminate 2 is a laminate in which a first release liner 11, a resin sheet 12, and a cushioning material 14 are laminated in this order. The cushioning material 14 is a material that softens or melts when heated and / or pressed, and has the function of promoting conformity of the resin sheet 12 to the semiconductor element. The cushioning material 14 is not particularly limited as long as it is a thermoplastic material, but it preferably has a melting temperature and / or Tg lower than the temperature at which it is heated and / or pressed. Suitable examples include polyolefin sheets, vinyl chloride sheets, and PVA sheets. Depending on the depth of the recesses formed between the semiconductor elements, the thickness of the cushioning material is typically about 100 μm to 1 mm. When multiple cushioning materials 14 are laminated, it is preferable that the total thickness be within this range.

[0098] 3 is a schematic cross-sectional view showing an example of a laminate according to Modification 2 of the present disclosure. This laminate 3 is composed of four layers: a first release liner 11, a first resin sheet 12a, a second resin sheet 12b, and a second release liner 13. The first resin sheet 12a is temporarily attached onto a semiconductor element. Like the laminate 3, the resin sheet may be composed of multiple layers.

[0099] 4 is a schematic top view showing an example of a laminate according to Variation 3 of the present disclosure. This laminate 4 is composed of a first release liner 11, a resin sheet 12, a conductive pattern 15, and a second release liner 13. The resin sheet 12 is an insulating sheet and primarily performs a sealing function. The conductive pattern 15 is formed in a desired position on the resin sheet 12. The conductive pattern 15 is used for purposes such as electrically connecting the encapsulated semiconductor element and / or mounting substrate to the outside.

[0100] 4. Methods for producing resin sheets, laminated sheets, and laminated bodies The method for producing the resin sheet is not particularly limited, but a suitable example is a method in which a resin composition obtained by adding an arbitrary solvent to the components constituting the resin sheet is coated on a substrate, etc. The solvent is added for the purpose of adjusting the viscosity to a level suitable for coating. The method for manufacturing this laminated sheet is not particularly limited, but includes a method in which a functional sheet is formed in the same manner as the resin sheet and then laminated with a resin sheet, a method in which a functional sheet is coated on a resin sheet, or a method in which a resin sheet is coated on a functional sheet. Coating can be performed using a comma coater, die coater, roll coater, lip coater, reverse coater, gravure coater, bar coater, curtain coater, dip coating, spin coating, silk screen, casting, etc. After coating, the solvent contained in the resin composition can be removed by heating and drying the coated film using a hot air oven, infrared heater, etc.

[0101] Laminates can be manufactured by known methods. For example, laminates can be manufactured by laminating each sheet after production. The laminate 1 in FIG. 1 can be obtained, for example, by coating a resin composition on a first release liner 11 and drying the coating to form a resin sheet 12, and then laminating the resin sheet 12 with a second release liner 13. The laminate 2 in FIG. 2 can be obtained, for example, by coating a resin composition on a first release liner 11 and drying the coating to form a resin sheet 12, and then laminating the exposed surface of the resin sheet 12 with a cushioning material 14. The laminate 3 in FIG. 3 can be obtained, for example, by manufacturing a laminate of the first release liner 11 and a first resin sheet 12a constituting the resin sheet, and a laminate of the second release liner 13 and a second resin sheet 12b constituting the resin sheet, each manufactured by the same method as for the laminate 1, and then laminating them together. The laminate of Figure 4 can be obtained, for example, by obtaining a laminate of a first release liner 11 / resin sheet 12, forming a conductive pattern 15 on the resin sheet 12 using a photoresist or the like, and laminating a second release liner 13 onto the conductive pattern 15.

[0102] 5. Semiconductor device and manufacturing method thereof The manufacturing method of the semiconductor device of this embodiment is a manufacturing method of a semiconductor device that collectively covers multiple semiconductor elements mounted on a substrate, and includes the steps of temporarily attaching the resin sheet to the side of the multiple semiconductor elements, softening the resin sheet by heating and / or pressurizing it to cover and bond the upper surface of the substrate and the upper and side surfaces of the multiple semiconductor elements, and hardening the resin sheet to seal the semiconductor elements.

[0103] The resin sheet may be a single layer or multiple layers of the resin sheet of the present disclosure. Alternatively, the resin sheet may be a laminated sheet in which a single layer or multiple layers of the resin sheet and one or more functional sheets are laminated. Furthermore, the resin sheet alone or the laminated sheet may be a laminated resin sheet in which materials used in the manufacturing process or until the manufacturing process are integrated.

[0104] An example of a schematic cross-sectional view of the semiconductor device of this embodiment is shown in Fig. 11. An example of a method for manufacturing the semiconductor device 100 will be described with reference to the cross-sectional views of the manufacturing steps shown in Figs. 5 to 10. However, the method for manufacturing the semiconductor device of this embodiment is not limited to the following method. 5, a mounting substrate 21 on which a conductor pattern 22 such as electrode pads and connection wiring is formed is prepared, and a semiconductor element 24 is mounted via bumps 23. The gap between the semiconductor element 24 and the mounting substrate 21 is filled with an underfill material 25. The size of the semiconductor element is, for example, 1000 μm or less in thickness and 1,000,000 μm in plan view area. 2 The thickness is preferably 800 μm or less, and the area in plan view is 640,000 μm or less. 2 The following is more preferable: a thickness of 500 μm or less and a planar area of ​​250,000 μm 2 The following is more preferable: The interval between the semiconductor elements mounted on the substrate is, for example, 10 to 5000 μm.

[0105] Next, the first release liner 11 is peeled off from the laminate 1, and the exposed resin sheet 12 is placed on the semiconductor element 24 and temporarily attached. Temporary attachment can be performed, for example, by heat pressing. Thereafter, the second release liner 13 is peeled off, and a cushioning material 16 is further placed on the resin sheet 12 (see FIG. 6). A protective sheet such as a release sheet (not shown) may be further placed on the cushioning material 16.

[0106] Next, under reduced pressure, heating and / or pressure is applied from the cushion material 16 side, and the resin sheet 12 softens and deforms due to the pressing force of the cushion material 16, thereby covering the semiconductor element 24 (see FIG. 7). Note that reduced pressure conditions are not essential, and the process may be carried out at normal pressure or in a vacuum. Thereafter, the cushion material 16 is peeled off, and the covered resin sheet is thermally cured to form the encapsulation layer 17 as a cured product (see FIG. 8). Note that although the method of further performing a thermal curing process after peeling off the cushion material has been described, the thermal curing process may also be carried out before peeling off the cushion material. The curing reaction progresses during the aforementioned heating and / or pressure application, and by using a resin sheet that has a moderate elongation even in the cured sealing layer, it is thought that peeling, cracks, and gaps at corners can be suppressed even under room temperature conditions.

[0107] As shown in FIG. 8, the present resin sheet can cover the recesses formed between semiconductor elements in accordance with their shapes. Therefore, the thickness of the present resin sheet can be determined based on the thickness required for the encapsulation layer. This prevents loss of the present resin sheet compared to the mode in which the recesses are filled, as in Patent Document 3. However, in cases where the size of the recesses is small compared to the desired thickness of the encapsulation layer, the present resin sheet may be filled into the recesses instead of covering them, and this does not exclude the filling mode.

[0108] The pressing method is not particularly limited, but heat pressing and / or vacuum pressing are preferred. From the viewpoint of the filling property of the resin sheet, the pressing temperature is preferably 20 to 200°C, more preferably 30 to 150°C, even more preferably 40 to 130°C, and particularly preferably 60 to 110°C. The curing conditions after peeling off the cushioning material 16 can be appropriately designed as long as the thermosetting resin is cured. For example, the heating temperature is preferably 40 to 250°C, more preferably 80 to 220°C, and even more preferably 100 to 190°C. The heating time is preferably 30 to 300 minutes, more preferably 60 to 240 minutes, and even more preferably 90 to 180 minutes. By using the above heating temperature and heating time, the curing of the resin composition constituting the resin sheet is promoted, residual stress in the sealing layer can be removed, and the quality of the sealing layer can be improved. Through these processes, the sealing layer is formed from the resin sheet. The average thickness of the sealing layer (cured product) can be appropriately designed, but is preferably 10 to 300 μm.

[0109] Next, half-cut grooves 26 are formed in the mounting substrate 21 (see FIG. 9). The half-cut grooves can be manufactured by a known method. For example, the half-cut grooves can be formed by dicing. Instead of the half-cut grooves, contact holes may be formed by laser processing.

[0110] Thereafter, conductive sheet 18 is placed on sealing layer 17 and temporarily attached to sealing layer 17, and cushioning material 16 is further placed on conductive sheet 18 (see FIG. 10). A release sheet or the like (not shown) may further be placed on cushioning material 16.

[0111] Next, under reduced pressure, heat and / or pressure is applied from the cushion material 16 side, whereby the conductive sheet 18 is deformed by the pressing force of the cushion material 16 to cover the sealing layer 17. Then, by peeling off the cushion material 16, the conductive layer 19 is collectively covered on the sealing layer 17. Through these steps, the semiconductor device 100 is formed (see FIG. 11).

[0112] The resin sheet of the present invention has high conformability to uneven surfaces, making it suitable for use in encapsulating multiple semiconductor elements. In the above embodiment, a manufacturing example has been described in which a sealing layer 17 is formed using a resin sheet 12, and a conductive layer 19 is formed thereon. In this semiconductor device, for example, a sealing layer or the like may be formed using a laminate shown in FIGS. 2 to 4. A laminate sheet may also be used instead of a resin sheet. Note that, although a method for manufacturing a semiconductor device using the resin sheet has been described above, a similar method can also be used when using the laminate sheet. [Example]

[0113] The present disclosure will be specifically described below with reference to examples and comparative examples, but the present disclosure is not limited to these examples. In the following description, "parts" and "%" represent "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0114] The values ​​obtained in this example were obtained by the following method. [Weight average molecular weight (Mw)] Mw is a polystyrene-equivalent value determined by GPC (gel permeation chromatography) measurement under the following measurement conditions: Apparatus: Shodex GPC System-21 (Showa Denko K.K.) Column: A column consisting of one Shodex KF-802 (Showa Denko K.K.), one Shodex KF-803L (Showa Denko K.K.), and one Shodex KF-805L (Showa Denko K.K.) connected in series. Solvent: tetrahydrofuran Flow rate: 1.0mL / min Temperature: 40℃ Sample concentration: 0.2% Sample injection volume: 100 μL

[0115] [Acid value] The acid value (mgKOH / g) was measured in accordance with the potentiometric titration method of JIS K0070 using an automatic titrator GT-200 manufactured by Mitsubishi Chemical Analic Corporation, and was calculated by converting the measured acid value into solid content.

[0116] [Tg of resin (A)] The coating solution of resin (A) was applied to the release layer of a 75 μm-thick second release liner (Mitsui Chemicals Tohcello, Inc., SP-PET-O3) to a dry thickness of 25 μm and dried in a hot air oven at 100°C for 3 minutes. The release layer of a 50 μm-thick first release liner (Mitsui Chemicals Tohcello, Inc., SP-PET-O1) was then bonded to the resin (A) side. The first and second release liners were then peeled off, and the Tg of the resulting resin (A) was measured using a differential scanning calorimeter (TA Instruments, "Discovery DSC 2500"). Approximately 2 mg of sample was placed in an aluminum pan, weighed, and inserted into the differential scanning calorimeter. The sample was held at 100°C for 5 minutes, followed by rapid cooling to -50°C using liquid nitrogen, using an aluminum pan of the same type but without the sample as a reference. Thereafter, the temperature was increased at a rate of 5°C / min, and the Tg of the resin (A) was determined from the obtained DSC chart.

[0117] [Production example of resin (A)] [Production Example of Urethane Resin (A1-1) R1] A reaction vessel (hereinafter simply referred to as "reaction vessel") equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube was charged with 130 parts of Pripol 2033 as a dimer diol, 8 parts of dimethylol butanoic acid (DMBA) as a polyol other than dimer, 85 parts of isophorone diisocyanate (IPDI) as a polyisocyanate, and 100 parts of toluene, and the mixture was reacted for 8 hours at 80°C under a nitrogen atmosphere. An appropriate amount of toluene was added to the mixture to obtain a 30% solids solution of urethane resin R1 with an acid value of 10 mgKOH / g, Mw of 60,000, and Tg of 0°C.

[0118] [Production example of urethane urea resin (A1-2) R2] A reaction vessel was charged with 130 parts of Pripol 2033 as a dimer diol, 8 parts of dimethylol butanoic acid as a non-dimer polyol, 85 parts of isophorone diisocyanate as a polyisocyanate, and 100 parts of toluene, and the mixture was allowed to react for 8 hours at 80°C under a nitrogen atmosphere. 122 parts of toluene was added to obtain a solution of a urethane prepolymer having an isocyanate group at its end. The resulting prepolymer solution was heated to 70°C and maintained at that temperature. A solution containing 67 parts of Priamin 1075 as a dimer diamine, 140 parts of isopropyl alcohol, and 331 parts of methyl ethyl ketone was added dropwise over 1 hour. After the addition, the mixture was allowed to react for another 8 hours at 70°C. An appropriate amount of toluene was added to the mixture to obtain a 30% solids solution of urethane urea resin R2 with an acid value of 10 mgKOH / g, Mw of 190,000, and Tg of 23°C.

[0119] [Production examples of urethane urea resins (A1-2, etc.) R3 to R9)] Urethane urea resins R3 to R9 were produced in the same manner as urethane urea resin R2, except that the compositions and blending amounts (parts by mass) were changed as shown in Table 1. Note that blank spaces indicate that no blending was performed. The acid value, Mw, and Tg are shown in Table 1.

[0120] [Production example of (meth)acrylic resin R10] A reaction vessel was charged with 80 parts ethyl acetate, 20 parts methyl methacrylate, 79 parts n-butyl methacrylate, 1 part methacrylic acid, and 0.1 parts 2,2'-azobisisobutyronitrile as an initiator, and the atmosphere inside the reaction vessel was replaced with nitrogen gas. The mixture was then heated to 65°C while stirring under a nitrogen atmosphere to initiate the reaction. The reaction solution was then reacted at 65°C for 4 hours. After the reaction was completed, the mixture was cooled and diluted with ethyl acetate to obtain a 25% solids solution of (meth)acrylic resin R10 with a Mw of 35,000, a Tg of 35°C, and an acid value of 7 mgKOH / g.

[0121] The abbreviations in the table are as follows: (Dimer diol) Pripol 2033: Croda Japan Co., Ltd. (carbon number: 36, hydroxyl value: 209 mg KOH / g) (Other polyols) CHDM: Cyclohexanedimethanol GI-1000: G-1000 manufactured by Nippon Soda Co., Ltd. (hydroxyl value: 75.5 mg KOH / g, number average molecular weight: 1486) HDO: 1,6-hexanediol DMBA: Dimethylolbutanoic acid (Polyisocyanate component) IPDI: Isophorone diisocyanate HDI: Hexamethylene diisocyanate (Dimer diamine) Priamine 1075: Croda Japan Co., Ltd. (amine value: 208 mg KOH / g, diamine content: 98% or more) (Other polyamines) IPDA: Isophoronediamine (Other ingredients) DnBA: di-n-butylamine Silica: SiO2 (AEROSIL 50, manufactured by Nippon Aerosil Co., Ltd., number average primary particle diameter 50 nm, specific surface area by BET method 35 to 65 m 2 / g)

[0122] [Production example of resin composition] [Example 1] As the resin (A1-1), 333 parts of a solution of urethane resin R1 (100 parts of resin (A), 233 parts of solvent) was mixed with 5 parts (solids equivalent) of an epoxy compound (JER1031S, manufactured by Mitsubishi Chemical Corporation) and 1 part (solids equivalent) of an imidazole compound (Curesol 2PZ, manufactured by Shikoku Chemicals Corporation) as the crosslinking agent (B). Next, an appropriate amount of toluene was added, and the mixture was filtered through a membrane filter with a pore size of 10 μm to remove coarse foreign matter that may cause coating unevenness, yielding a resin composition with a solids content of 25%.

[0123] [Examples 2 to 11, Comparative Examples 1 and 2] Resin compositions were prepared in the same manner as in Example 1, except that the components, blending amounts (blending amounts converted into solid content), etc. were changed as shown in Table 2.

[0124] [Examples of manufacturing resin sheets and laminates] Each resin composition of the Examples and Comparative Examples was applied to the release layer of a 75 μm-thick second release liner (Mitsui Chemicals Tohcello, Inc., SP-PET-O3) so that the dried thickness would be 50 μm (for the resin sheet used to measure dielectric properties, the coating was applied so that the dried film thickness would be 200 μm), and then dried in a hot air oven at 100°C for 3 minutes to form a resin sheet on the release liner. Next, the release layer side of a 50 μm-thick first release liner (Mitsui Chemicals Tohcello, Inc., SP-PET-O1) was attached to the exposed resin sheet, yielding laminates of Examples 2 to 11 and Comparative Examples 1 and 2, in which the first release liner / resin sheet / second release liner were laminated in this order.

[0125] [Elongation at break] Each laminate was cut into a size of 15 mm wide x 20 mm long. The first and second release liners were then peeled off to obtain a resin sheet specimen. Each resin sheet was heated at 150°C for 1 hour, and then the specimen was subjected to a tensile test at room temperature (23°C), a pulling rate of 50 mm / min, and a relative humidity of 50% using a tensile tester to measure the elongation at which the coating broke (according to the method specified in JIS K7161:1994). The elongation was defined as 0% when no deformation occurred, 100% when the stretched length doubled, and 200% when the stretched length tripled.

[0126] [Breaking strength] The strength of each sample at the time of break was determined under the same conditions as in the measurement of breaking elongation.

[0127] [Peeling strength after wet heat test] For each laminate, the first and second release liners were removed from the resin sheet, which was sandwiched between two 50 μm PPS (polyphenylene sulfide) substrates (Toray Industries, Inc., Torelina #50 3030) and thermocompression bonded at 5 MPa and 80°C. The resulting laminate was then heated at 150°C for one hour. A two-week wet heat test was then performed at 121°C and 100% humidity. After these steps, a peel test was performed on the resulting specimen between one PPS substrate and the resin sheet at a peel angle of 90° and a peel rate of 300 mm / min. If the peel strength was measurable, the value was recorded. If at least a portion of the resin sheet was broken and the peel strength could not be measured, the value was marked as "Good."

[0128] [Dielectric properties of resin sheet after heat treatment] The resin sheet of each example (film thickness after drying: 200 μm) was heated at 150°C for 1 hour, and then the relative permittivity and dielectric loss tangent of the sheet were determined using a dielectric constant measuring device manufactured by AET Corporation by the cavity resonator method at a measurement temperature of 23°C and a measurement frequency of 10 GHz.

[0129] [Tg of resin sheet after heat treatment] The resin sheet of each example (film thickness after drying: 50 μm) was heated at 150° C. for 1 hour, and then the Tg was measured in the same manner as for the Tg of resin (A).

[0130] [Tensile storage modulus and Tanδ peak value of resin sheet after heat treatment] The resin sheet (50 μm film thickness after drying) of each example was heated at 150 ° C for 1 hour and measured using a dynamic modulus measuring device (model number: DVA-200, manufactured by IT Measurement Control) under the conditions of "tensile" deformation mode, frequency 10 Hz, heating rate 10 ° C / min, and measurement temperature range -30 to 200 ° C, and the measured values ​​of tensile storage modulus at 25 ° C and 150 ° C were read. In addition, the loss tangent was calculated by dividing the value of the loss modulus measured at the same time by the value of the storage modulus, and the Tan δ peak value at -30 to 200 ° C was read.

[0131] [Preparation of test substrate] A substrate was prepared in which non-molded semiconductor elements (1 × 1 cm) 24a were mounted in a 5 × 5 array on a substrate 21a made of glass epoxy. The thickness of the substrate 21a was 0.3 mm, and the thickness of the semiconductor elements 24a, i.e., the height from the upper surface of the substrate 21a to the top surface of the semiconductor elements 24a, was 0.7 mm (see FIG. 12). To evaluate under harsh conditions where gaps are likely to occur in the coating, the angle between the substrate 21a and the semiconductor elements 24a was set to 90° (the corners (see FIG. 13) were 90°).

[0132] [Evaluation method and criteria] [Water-resistant insulation] The first and second release liners of each 50mm wide x 100mm long laminate were peeled off, and the exposed resin sheet (50μm thick after drying) was pressed against a 70mm wide x 120mm long Kapton 300H sheet at 170°C, 2.0MPa, and 30 minutes, followed by thermal curing to obtain a test piece. The surface resistance of the test piece resin sheet was measured at 23°C and 50%RH using a ring probe URS on a Mitsubishi Chemical Analytech Hiresta UP MCP-HT800, and this was recorded as the initial surface resistance. The test piece was then left to stand at 121°C and 100% RH for one week, and then at 23°C and 50% RH for one hour, and the surface resistance was measured in the same manner as the initial value, and this was taken as the surface resistance value after the water resistance test. The difference between the initial surface resistance value and the surface resistance value after the water resistance test was calculated and evaluated according to the following criteria. A: The difference is 1.0 x 10 2 Ω / □ or less. B: The difference is 1.0 x 10 2 / □ over, 1.0×10 3 Ω / □ or less. C: The difference is 1.0 x 10 3 Ω / □ over 1.0×10 4 Ω / □ or less. D: The difference is 1.0 x 10 4 Ω / □ over 1.0×10 5 Ω / □ or less. E: The difference is 1.0 x 10 5 Over Ω / □.

[0133] [Coating] Each laminate was cut to a 10 cm x 10 cm size, and the first release liner was peeled off to expose the resin sheet. The resin sheet side was then placed on the semiconductor element of the test substrate. The second release liner on the opposite side was then peeled off, and a 50 μm-thick TPX (Opulent X-44B, manufactured by Mitsui Chemicals Tocello) and a 2.0 mm-thick PVC film (Celeb T, manufactured by Okamoto Corporation) were laminated in this order as cushioning materials on the exposed surface, followed by cardboard to prevent sticking. Next, the test specimen was pressed against the substrate surface from above at 5 MPa and 160°C for 30 minutes, covering the resin sheet along the shape of the semiconductor element and forming an encapsulating layer. The cushioning material and cardboard were then peeled off. The encapsulating layer that protruded from the test substrate of the obtained test specimen was roughly removed using a cutter, and a cross section of the test substrate was formed by polishing, allowing observation of the gap between the semiconductor elements. Coverage was evaluated by observing the gap between the semiconductor elements with an electron microscope (magnification: 500x). Between the semiconductor elements, the sealing layer and the test substrate were deemed to be covered when the maximum diameter of the gap 51 at the corner (encircled line in FIG. 13) was 10 μm or less. The pass rate of the coverage test on the observed cross section was determined and evaluated according to the following criteria. A: 100%. B: Does not meet criterion A and is 90% or higher. C: Does not meet criteria A or B and is 80% or higher. D: Does not meet criteria A to C and is 70% or more. E: Does not meet any of the criteria A to D.

[0134] [Storage stability] Four samples of each laminate were prepared and stored at -10°C, 0°C, 15°C, and 25°C for 48 hours at 50% humidity. Test pieces were then prepared using the same method as in the evaluation of coating properties and evaluated in the same manner as in [Coating Properties] above. That is, the clear rate of the coating test on the observed cross section was determined and evaluated according to the following criteria. A: For test pieces prepared after storing the laminate at 25°C, the pass rate in the coating test is 70% or more. B: Not applicable to standard A, and the pass rate of the coating test for test pieces prepared after storing the laminate at 15°C is 70% or more. C: Not applicable to criteria A and B, and the pass rate of the coating test for test pieces prepared after storing the laminate at 0°C is 70% or more. D: Not applicable to criteria A to C, and the pass rate of the coating test for test pieces prepared after storing the laminate at -10°C is 70% or more. E: Does not meet criteria A to D.

[0135] [tear] As in the evaluation of coating properties, using a test substrate of a test piece on which a sealing layer was formed, the number of tears (maximum length 1 μm or more) present in the sealing layer was counted under a microscope (magnification 50x) and evaluated according to the following criteria. A: The number of tears is 0 to 1. B: The number of tears is 2 to 5. C: The number of tears is 6 to 10. D: The number of tears is 11 to 15. E: The number of tears is 16 or more.

[0136] All of the above evaluations were rated on a five-point scale, with A being particularly outstanding, B being the next best, C being the next best, D being practical, and E being the failure to achieve the target performance.

[0137] [Table 1]

[0138] [Table 2]

[0139] When a resin sheet having an elongation at break of less than 100% at 23°C after heat treatment at 150°C for 1 hour was used, it was confirmed that there were problems with coverage, storage stability, and tearing, as shown in Comparative Example 1. Furthermore, when a resin sheet having a dielectric constant that does not satisfy the requirements of 3 or less and 0.01 or less after heat treatment at 150°C for 1 hour was used, it was confirmed that there were problems with water-resistant insulation, as shown in Comparative Example 2. On the other hand, when a resin sheet according to the present disclosure having an elongation at break of 10 to 400% at 23°C after heat treatment at 150°C for 1 hour, and a dielectric constant of 3 or less and a dielectric dissipation factor of 0.01 or less after heat treatment at 150°C for 1 hour was used, it was confirmed that a resin sheet having excellent coverage, high productivity, and excellent reliability could be obtained, as shown in Examples 1 to 11.

[0140] The storage stability of a resin sheet is significantly affected by the reactivity of the crosslinking agent used. In other words, when a highly reactive crosslinking agent is used as a component of the resin sheet, refrigerated or frozen storage may be necessary to maintain quality. In this example, evaluation was performed using a highly reactive crosslinking agent. By setting the elongation at break after the heat treatment of the resin sheet to a specific range and the dielectric properties to a specific range, it was confirmed that excellent storage stability was achieved, as shown in Examples 1 to 11. Furthermore, it was confirmed that even better storage stability could be achieved by using a urethane-based resin (A1) having a dimer structure as the resin (A) or by adjusting the amount of the crosslinking agent (B) appropriately. [Explanation of symbols]

[0141] 1 to 4: Laminate 11: First release liner 12: Resin sheet 13: Second release liner 14, 16: Cushioning material 15: Conductor pattern 17: Sealing layer 18: Conductive sheet 19: Conductive layer 21: Mounting board 22: Conductor pattern 23: Bump 24: Semiconductor element 25: Underfill material 26: Half cut groove 51: Gap 100: Semiconductor device

Claims

1. A resin sheet for semiconductor encapsulation for forming an encapsulation layer of a semiconductor element, the resin sheet is a thermosetting composition containing a resin (A) and a crosslinking agent (B), the resin sheet has an elongation at break of 10 to 400% at 23°C after being heated at 150°C for 1 hour; The resin sheet for semiconductor encapsulation has a relative dielectric constant of 3 or less at a frequency of 10 GHz and 23°C after heating the resin sheet at 150°C for 1 hour, and a dielectric loss tangent of 0.01 or less at a frequency of 10 GHz and 23°C.

2. 2. The resin sheet for semiconductor encapsulation according to claim 1, wherein the resin sheet is sandwiched between two 50 μm PPS (polyphenylene sulfide) substrates, thermocompressed at 5 MPa and 80° C., then heat-treated at 150° C. for 1 hour, and then subjected to a two-week wet heat test under conditions of 121° C. and 100% humidity. When a peel test is performed between one of the PPS substrates and the resin sheet under conditions of a peel angle of 90° and a peel speed of 300 mm / min, at least a portion of the material breaks.

3. 2. The resin sheet for semiconductor encapsulation according to claim 1, wherein the resin (A) comprises a urethane-based resin (A1) that contains a structural unit derived from at least one polyol selected from the group consisting of dimerdiol and trimertriol, and / or a structural unit derived from at least one polyamine selected from the group consisting of dimerdiamine and trimertriamine, and that has a urethane bond and may also have a urea bond.

4. 4. The resin sheet for semiconductor encapsulation according to claim 3, wherein the urethane resin (A1) has an acid value of 1 to 20 mgKOH / g.

5. 4. The resin sheet for semiconductor encapsulation according to claim 3, wherein the urethane resin (A1) has a weight average molecular weight of 50,000 to 200,000.

6. 2. The resin sheet for semiconductor encapsulation according to claim 1, wherein the crosslinking agent (B) contains an epoxy compound.

7. A laminated sheet comprising the resin sheet according to any one of claims 1 to 6 and one or more functional sheets laminated together.

8. A semiconductor device comprising: a substrate; a semiconductor element mounted on the substrate; and a sealing layer that seals the semiconductor element, wherein the sealing layer is formed from a cured product of the resin sheet according to any one of claims 1 to 6.

9. 9. The semiconductor device according to claim 8, wherein the average thickness of the cured product is 10 to 300 μm.

10. A method for manufacturing a semiconductor device that collectively covers a plurality of semiconductor elements mounted on a substrate, comprising: a step of temporarily attaching the resin sheet according to any one of claims 1 to 6 to the side of the plurality of semiconductor elements; a step of softening the resin sheet by heating and / or pressurizing the resin sheet, and covering and bonding the upper surface of the substrate and the upper and side surfaces of the plurality of semiconductor elements; and curing the resin sheet to encapsulate the semiconductor element.

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