Resin sheet for sealing hollow electronic component, and hollow electronic component

Abstract

Provided are: a resin sheet for sealing a hollow electronic component, the resin sheet being capable of achieving both excellent flexibility and low thermal expansion; and a hollow electronic component using the resin sheet. A resin sheet for sealing a hollow electronic component, the resin sheet being used for forming a sealing layer of a hollow electronic component, the resin sheet being a resin composition containing (A) a thermosetting resin, (B) a polyfunctional maleimide compound having two or more maleimide groups, (C) a benzoxazine compound, and (D) an epoxy resin.

Description

Technical Field

[0001] This disclosure relates to a resin sheet for sealing hollow electronic components and a hollow electronic component. Background Technology

[0002] Hollow electronic components, such as surface acoustic wave (SAW) filters that allow only signals of a specific frequency to pass through and provide noise cutoff, include a sealing layer to protect the electronic components from physical shocks or temperature changes. The sealing layer is required to seal the electronic components while maintaining a hollow structure between the electronic components and the substrate.

[0003] As a sealing layer, many hot-melt resin sheets have been developed that easily maintain a hollow structure and thus have excellent dimensional stability.

[0004] Patent Document 1 discloses a hollow sealing resin sheet containing 70% to 90% by volume of an inorganic filler, and whose physical properties such as the coefficient of linear expansion are within a specific range.

[0005] [Existing technical documents]

[0006] [Patent Literature]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2014-209568 Summary of the Invention

[0008] [The problem the invention aims to solve]

[0009] For resin sheets used to seal hollow electronic components, it is required that the sheet has the flexibility to stretch so as to uniformly coat electronic components of various shapes with height differences. In addition, from the viewpoint of preventing the solder that bonds the substrate to the electronic component from cracking, it is ideal for the resin sheet for sealing hollow electronic components to have low thermal expansion.

[0010] The softness and thermal expansion are usually trade-offs. Although the resin sheet described in Patent Document 1 can suppress thermal expansion to a low level, it contains a large amount of inorganic filler, so the softness is not sufficient.

[0011] This disclosure is made in view of the aforementioned issues, and its object is to provide a resin sheet for sealing hollow electronic components that can achieve both excellent flexibility and low thermal expansion, and a hollow electronic component using the resin sheet.

[0012] [Technical means to solve the problem]

[0013] The inventors have conducted repeated and diligent research and have found that the problems of this disclosure can be solved in the following forms, thereby completing this disclosure.

[0014] [1] A resin sheet for sealing hollow electronic components, which is a resin sheet for sealing hollow electronic components to form a sealing layer of hollow electronic components, wherein the resin sheet is a resin composition comprising a thermosetting resin (A), a polyfunctional maleimide compound having two or more maleimide groups (B), a benzoxazine compound (C) and an epoxy resin (D).

[0015] [2] According to the resin sheet for sealing hollow electronic parts as described in [1], the total content of the polyfunctional maleimide compound (B), benzoxazine compound (C) and epoxy resin (D) having two or more maleimide groups in the resin composition is 5 to 180 parts by mass relative to 100 parts by mass of thermosetting resin (A).

[0016] [3] The resin sheet for sealing hollow electronic components according to [1] or [2], wherein the resin composition further comprises an inorganic filler (E) comprising silica particles.

[0017] [4] According to [3], the content of inorganic filler (E) in the resin composition is 5% to 70% by mass.

[0018] [5] A resin sheet for sealing hollow electronic parts according to any one of [1] to [4], wherein the coefficient of linear expansion of the cured material obtained by curing the resin sheet at 180°C for 2 hours is 3 ppm / K to 750 ppm / K at 150°C to 200°C.

[0019] [6] A resin sheet for sealing hollow electronic parts according to any one of [1] to [5], wherein the elongation at break at 100°C is 300% to 2000%.

[0020] [7] A resin sheet for sealing hollow electronic components according to any one of [1] to [6], wherein the adhesive strength of the cured material formed by bonding the resin sheet to a polyimide substrate and curing it at 180°C for 2 hours is 0.6 N / cm to 40 N / cm at 25°C.

[0021] [8] A hollow electronic component includes: a substrate; an electronic component mounted on the substrate; and a sealing layer that seals the electronic component while maintaining a hollow structure between the substrate and the electronic component, the sealing layer being formed from a hardened resin sheet for sealing hollow electronic components according to any one of [1] to [7].

[0022] [The effects of the invention]

[0023] This disclosure provides the following excellent effects: it provides a resin sheet for sealing hollow electronic components that can achieve both excellent flexibility and low thermal expansion, and a hollow electronic component using the resin sheet. Attached Figure Description

[0024] Figure 1 of (a) Figure 1 (b) is a schematic cross-sectional view showing two examples of hollow electronic components in this embodiment.

[0025] Figure 2 of (a) Figure 2 (b) is a schematic diagram of the experimental substrate of this embodiment.

[0026] Explanation of icon numbers

[0027] 1, 11: substrate

[0028] 2, 12: Electronic components

[0029] 3: Hollow structure

[0030] 4: Sealing layer (first sealing layer)

[0031] 5: Second sealing layer

[0032] 6, 13: Welding balls

[0033] 10: Hollow electronic components

[0034] 20: Test substrate Detailed Implementation

[0035] The following provides a detailed description of the resin sheet for sealing hollow electronic components and the hollow electronic components using the resin sheet.

[0036] Furthermore, other embodiments are also included within the scope of this disclosure as long as they are consistent with the spirit of this disclosure.

[0037] In this specification, the numerical range specifically specified by “~” includes the values ​​before and after “~” as the lower limit and upper limit.

[0038] In the numerical ranges described in this specification, the upper or lower limit of one numerical range may be replaced by the upper or lower limit of another numerical range described in other stages. Furthermore, the upper or lower limit of the numerical ranges described in this specification may also be replaced by the values ​​shown in the embodiments.

[0039] Unless otherwise specified, each component in this specification may be used independently or in combination with two or more. The numerical values ​​described in this specification refer to values ​​obtained through the methods described in the [Examples] and other sections described later.

[0040] 1. Resin sheets for sealing hollow electronic components

[0041] The resin sheet for sealing hollow electronic components disclosed herein (hereinafter also referred to as the resin sheet) is a suitable sheet for the application of forming a sealing layer for sealing hollow electronic components (for sealing hollow electronic components). Figure 1 As shown in (a), the hollow electronic component (hollow-type device) includes: a substrate 1; an electronic component 2 mounted on the substrate 1; and a sealing layer 4 that seals the electronic component 2 while maintaining the hollow structure 3 (hollow portion) between the substrate 1 and the electronic component 2. Therefore, in the hollow electronic component 10, electronic components 2 of various shapes with height differences are uniformly covered by the sealing layer 4 while maintaining the hollow structure 3 between the substrate 1 and the electronic component 2. Thus, this resin sheet has the advantage of being able to uniformly seal multiple electronic components 2 formed on the substrate 1, etc. Of course, this resin sheet can also be used for sealing a single electronic component (semiconductor element). Furthermore, as... Figure 1 As shown in (b), the electronic component 2 can also be secondary-sealed using a second sealing layer 5 disposed on the sealing layer (first sealing layer) 4, which serves as a primary seal. Thus, the hollow electronic component of this disclosure can have a second sealing layer 5 formed on the sealing layer (first sealing layer) 4, and the electronic component can be sealed using multiple sealing layers. Furthermore, Figure 1 (a) and Figure 1 (b) is a schematic cross-sectional view showing two examples of the hollow electronic component 10 in this embodiment. Symbol 6 represents, for example, lead-free solder balls that bond the substrate 1 to the electronic component 2.

[0042] This resin sheet is a resin composition comprising a thermosetting resin (A), a polyfunctional maleimide compound having two or more maleimide groups (B), a benzoxazine compound (C), and an epoxy resin (D). When sealing electronic component 2 while maintaining a hollow structure, it is converted into a cured material, namely a sealing layer 4. This resin sheet can be a single layer or multiple layers. In the case of multiple layers, it is formed by stacking layers of resin compositions of the same type and / or different types. In addition, the thermosetting resin (A), the polyfunctional maleimide compound having two or more maleimide groups (B), the benzoxazine compound (C), the epoxy resin (D), and the inorganic filler (E) described later are referred to as components (A) to (E), respectively. Furthermore, the second sealing layer 5 may contain these components, which may also satisfy the structure of this resin sheet.

[0043] As described above, this resin sheet, due to its excellent flexibility, is suitable for forming a sealing layer 4 on unsealed electronic components 2 while maintaining a hollow structure 3. Furthermore, because this resin sheet is lightweight, offers high design flexibility, and can be integrated into complex shapes, it is suitable for mounting multiple sealed semiconductor chips onto a substrate and sealing them uniformly. Moreover, due to its low thermal expansion, this resin sheet prevents solder cracking during the fabrication of hollow electronic components.

[0044] In this specification, electronic component 2 is a component incorporated into an electrical circuit or electronic device and controlling electrical signals, and may include the following semiconductor elements. Semiconductor elements include: insulated gate bipolar transistors (IGBTs), metal oxide semiconductor field-effect transistors (MOSFETs), surface acoustic wave filters (SAW filters), bipolar transistors, diodes, and other power semiconductor elements; light-emitting elements such as light-emitting diodes (LEDs), light-receiving elements, and other light semiconductor elements; semiconductor integrated circuits formed on semiconductor substrates such as silicon substrates, and semiconductor chips obtained by monolithically processing semiconductor integrated circuits formed on semiconductor substrates.

[0045] This resin sheet allows for lightweight design and integration of complex shapes, offering high design flexibility and excellent dielectric properties, making it suitable for applications in the information and communication field. Electronic components such as semiconductor devices are typically formed or mounted on the upper surface of a substrate.

[0046] In this disclosure, sealing refers to covering an object (e.g., substrate 1 and electronic component 2) with the resin sheet while maintaining the hollow structure 3, and then curing it to form a sealing layer 4. The sealing layer 4 of this disclosure includes all forms of covering the electronic component 2, including forms that directly seal the electronic component 2, as well as forms that further seal semiconductor modules containing the electronic component 2. Among these, the resin sheet is particularly suitable for applications where a uniform seal is performed while preventing it from lifting or peeling off the substrate 1, due to its excellent flexibility, low thermal expansion, and consequently, excellent adhesion and heat resistance.

[0047] The coefficient of linear expansion and adhesive strength disclosed herein are based on conditions of a sufficiently cured stage for evaluating these properties, namely, curing (heating) the resin sheet at 180°C for 2 hours. Furthermore, the "sufficiently cured stage" may include not only the cured product but also a state of intermediate curing that is not a cured product. In this specification, a cured product refers to a state where it has been cured to the point that further heating will not substantially induce a curing reaction, and the sealing layer is defined as a (fully) cured product. During the formation of this resin sheet, a portion of it may undergo a curing reaction, but a state where further heating would allow it to harden is not included in the (fully) cured product described herein. In the resin composition (thermosetting resin composition) stage, a partially cured B-stage state may also be present. The cured product of the resin composition can generally be obtained by heat treatment at 100°C to 180°C for approximately 30 minutes to 5 hours.

[0048] Based on the above, this resin sheet may include a resin sheet before it is fully cured, more specifically, an uncured resin sheet, and a semi-cured resin sheet. Furthermore, the cured product of this resin sheet refers to the substance after the resin sheet has been fully cured.

[0049] The coefficient of thermal expansion (CTE) of the cured material, obtained by curing the resin sheet at 180°C for 2 hours, at 150°C to 200°C is preferably 3 ppm / K to 750 ppm / K. If the CTE is 3 ppm / K or higher, even if the encapsulated structure after sealing is subjected to high-temperature treatment, the difference in thermal expansion between the resin sheet and the substrate or electronic components can be reduced, easily preventing substrate warping, etc. Furthermore, from the same viewpoint, the CTE is more preferably 5 ppm / K or higher, more preferably 50 ppm / K or higher, and particularly preferably 120 ppm / K or higher. Furthermore, if the CTE is 750 ppm / K or lower, solder crack resistance is even better. Also from the same viewpoint, the CTE is more preferably 500 ppm / K or lower, more preferably 300 ppm / K or lower, and particularly preferably 200 ppm / K or lower. The method for measuring the CTE will be described later.

[0050] Furthermore, the coefficient of linear expansion can be adjusted by changing the types or amounts of components (B) to (E) in the resin composition. More specifically, it is believed that the rigid molecular structure of the polyfunctional maleimide compound (B), the structural stabilization brought about by the intramolecular hydrogen bonds formed by the benzoxazine compound (C), the increased crosslinking density brought about by the epoxy resin (D), and the high filling of the inorganic filler (E) contribute to the decrease in the coefficient of linear expansion.

[0051] The elongation at break of the resin sheet (before curing) at 100°C is preferably 300% to 2000%. If the elongation at break is 300% to 2000%, the coverage of recesses formed due to the mounting of electronic components is superior. More specifically, if the elongation at break is 300% or more, it can moderately possess deformable force and appropriately maintain fracture strength, significantly improving the situation of defects such as cracks and fractures in the sealing layer. From the same viewpoint, the elongation at break is more preferably 500% or more, more preferably 900% or more, and particularly preferably 1200% or more. Furthermore, if the elongation at break is 2000% or less, it is easier to prevent the resin sheet from entering the hollow portion. From the same viewpoint, the elongation at break is more preferably 1800% or less, more preferably 1600% or less, and particularly preferably 1500% or less.

[0052] Furthermore, when the elongation of the resin sheet is anisotropic, the direction with the lowest elongation is set to 300% or more, and the direction with the highest elongation is set to 2000% or less. The method for determining the elongation at break will be described later.

[0053] Furthermore, the elongation at break can be adjusted by changing the types of components (A) to (E) in the resin composition or by adjusting the amount added. More specifically, by introducing a rigid skeleton such as a polyfunctional maleimide compound (B) or by formulating an inorganic filler (E), the resin sheet becomes more elastic, and the elongation at break tends to decrease. On the other hand, by adding a thermoplastic resin or an epoxy resin (D) with a low melting temperature, the resin softens upon heating, and the flexibility tends to increase. In addition, the benzoxazine compound (C) tends to increase the elongation at break by increasing its molecular weight through B-stage crosslinking with a hardener or resin.

[0054] The adhesion strength of the cured product, formed by bonding the resin sheet to a polyimide substrate and curing (heating) at 180°C for 2 hours, at 25°C is preferably 0.6 N / cm to 40 N / cm. If the adhesion strength is 0.6 N / cm or higher, the resin sheet can be easily prevented from lifting and peeling off the bonded material during thermal shock testing. From the same perspective, the adhesion strength is more preferably 0.9 N / cm or higher, more preferably 1.2 N / cm or higher, and particularly preferably 1.5 N / cm or higher. Furthermore, if the adhesion strength is 40 N / cm or lower, the resin sheet can be easily peeled off again in case of processing defects or failure analysis, facilitating reprocessing and part recycling. From the same perspective, the adhesion strength is more preferably 25 N / cm or lower, more preferably 15 N / cm or lower, and particularly preferably 10 N / cm or lower.

[0055] Furthermore, the adhesive strength can be adjusted by modifying the amount of components (B) to (E) in the resin composition and the film thickness of the resin sheet. More specifically, by increasing the amount of polyfunctional maleimide compound (B) or benzoxazine compound (C) and epoxy resin (D), the crosslinking density within the resin sheet increases, tending to increase the adhesive strength. On the other hand, by increasing the amount of inorganic filler (E), the anchoring to the substrate is impaired, tending to decrease the adhesive strength. Additionally, by thinning the film thickness of the resin sheet, the stress generated at the bonding interface increases, tending to decrease the adhesive strength.

[0056] From the viewpoint of heat resistance, the heat resistance temperature (Tg) of the resin sheet after heating at 180°C for 2 hours is preferably 20°C to 200°C. The lower limit of Tg is more preferably 25°C, further preferably 30°C, and particularly preferably 40°C. The upper limit of Tg is more preferably 190°C, further preferably 180°C, and particularly preferably 170°C.

[0057] Furthermore, the Tg of the resin sheet can be adjusted by changing the amount of components (B) to (E) added to the resin composition. Specifically, by increasing the amount of polyfunctional maleimide compound (B) or benzoxazine compound (C) and epoxy resin (D), the rigid molecular structure in the resin sheet increases, thereby increasing the crosslinking density and thus raising the Tg.

[0058] The thickness of this resin sheet can be appropriately designed within the range that achieves the effects of this disclosure. For example, the thickness of this resin sheet can be set to 1 μm to 1000 μm. From the viewpoint of coverage and operability, 5 μm to 300 μm is suitable, and 10 μm to 100 μm is more preferred. By setting the thickness of this resin sheet to 1 μm or more, the pressure in the pressing process can be diffused within the resin sheet, and sufficient coverage can be easily achieved. By setting the thickness of this resin sheet to 1000 μm or less, the design freedom can be further improved. In addition, the pressure loss absorbed by this resin sheet is small in the pressure applied in the pressing process, and the resin (A) and the like flow sufficiently, thus excellent coverage can be easily achieved.

[0059] Previously, encapsulation layers (Encap) and the like have been used as sealing layers 4, but this sometimes presents challenges in terms of production. Therefore, when using coating types such as resin sheets, that is, when sealing layers 4 are applied along the shape of electronic components 2, gaps easily form between the adhered material and the coating layer in the uneven corners, especially right angles, formed by mounting electronic components 2. Consequently, these gaps tend to accumulate over time, sometimes making it difficult to maintain stability.

[0060] However, according to this resin sheet, the sealing layer 4 can be uniformly formed along electronic components 2 with various shapes having height differences, thus suppressing material loss of the resin sheet. Furthermore, since uniform coating is possible, productivity and design freedom are significantly improved. Moreover, by including the specific materials described later, this resin sheet significantly improves gaps generated at the corners (especially right angles and other shaped portions) between the adherend (electronic component 2) and the coating layer, achieving excellent coating properties. After forming the sealing layer 4, other functional layers such as conductive layers can be further coated, and functional layers can be stacked using the same equipment, thus resulting in excellent productivity.

[0061] This resin sheet can also be used as a laminate of one or more functional sheets. There are no particular limitations on the functional sheets. Specifically, examples of functional sheets include: electromagnetic wave shielding sheets, thermally conductive sheets that dissipate heat from semiconductor elements, shielding sheets that prevent visibility of semiconductor elements or block light, moisture-proof sheets that protect semiconductor elements from moisture, decorative sheets, flame-retardant sheets, protective sheets that provide hard coating properties, bonding sheets that improve adhesion to semiconductor elements, and any combination thereof. A functional layer can be formed by coating this resin sheet with functional sheets.

[0062] In addition, such as Figure 1 As shown in (b), a second sealing layer 5, such as in tablet, liquid, granular, or sheet form, can also be coated onto the resin sheet (sealing layer 4) to provide secondary sealing for the substrate 1 and electronic components 2. As the second sealing layer 5, a sealing material comprising, for example, known epoxy resin, hardener, inorganic filler, hardening catalyst, coupling agent, flame retardant, coloring material, etc., can be suitable. Furthermore, as described above, the second sealing layer 5 can satisfy the structure of the resin sheet.

[0063] This resin sheet can be suitably manufactured using existing known methods; for details, please refer to the examples described below.

[0064] 1-1. Resin Composition

[0065] This resin sheet is a resin composition (hereinafter also referred to as the "composition") comprising a thermosetting resin (A), a polyfunctional maleimide compound (B) having two or more maleimide groups, a benzoxazine compound (C), and an epoxy resin (D). Preferably, these components of the resin composition are cured together by heat treatment. Furthermore, a portion of the resin composition may also be cured during the resin sheet stage.

[0066] 1-1a. Thermosetting resins (A)

[0067] Thermosetting resin (A) functions as an adhesive to bond and fix objects. Thermosetting resin (A) may include thermoplastic resins, photocurable resins, etc., in addition to thermosetting resins, as long as it possesses thermosetting properties as a whole, or it may consist solely of thermosetting resins. Thermosetting resin is a resin having multiple functional groups available in a crosslinking reaction based on heating, and may also have functional groups capable of self-crosslinking.

[0068] The functional groups of the thermosetting resin can be appropriately selected based on their combination with other components described below. Examples include: hydroxyl, carboxyl, amino, epoxy, oxacyclobutyl, oxazoline, oxazinyl, aziridinyl, thiol, isocyanate, block isocyanate, and silanol. From a reactivity point of view, the functional groups are preferably carboxyl, hydroxyl, or epoxy.

[0069] The acid value of the thermosetting resin is preferably 1 mgKOH / g to 30 mgKOH / g, more preferably 2 mgKOH / g to 20 mgKOH / g, and even more preferably 3 mgKOH / g to 15 mgKOH / g. By setting the acid value of the thermosetting resin to 1 mgKOH / g or higher, the crosslinking density with other components is optimized while maintaining good intermolecular forces with the adhered materials such as electronic components, thereby further improving the sealing performance. Furthermore, by setting the acid value of the thermosetting resin to 30 mgKOH / g or lower, the intermolecular forces with the adhered materials such as electronic components are well maintained, and the adhesion is further improved.

[0070] The content of thermosetting resin (A) in this resin sheet (solid component) is preferably 20% to 50% by mass. Examples of thermosetting resin (A) include, for example, amide resins, imide resins, (meth)acrylic resins, maleic acid resins, butadiene resins, urethane resins or urethane urea resins, oxetane resins, phenoxy resins, polyamide-imide resins, alkyd resins, amino resins, polylactic acid resins, oxazoline resins, benzoxazine resins, silicone resins, and fluororesins. Among these, thermosetting resin (A) is preferably a urethane resin comprising urethane resin and / or urethane urea resin. Existing known resins may be used, for example, commercially available products may be used.

[0071] The weight-average molecular weight (Mw) of the thermosetting resin (A) can be appropriately designed, and from the viewpoint of improving the mechanical strength of the sealing layer and the storage stability of the resin sheet, a value of 10,000 to 1,000,000 is suitable. From the viewpoint of durability and adhesion, a value of 25,000 to 300,000 is more preferred, and even more preferably 50,000 to 200,000. The ratio of the number-average molecular weight (Mn) to Mw (Mw / Mn), which represents the dispersibility of the thermosetting resin (A), is preferably 1.0 to 17, more preferably 1.5 to 14, and even more preferably 2.0 to 10. By setting Mw / Mn to 1.0 to 17, the flowability of the resin is more easily controlled, and the coating properties are further improved. In addition, since the speed of wetting the adhered material is also uniformized, the adhesion is further improved.

[0072] Carbamate resins can be suitably designed and are not limited in scope. Suitable carbamate resins include structural units derived from at least one polyol from dimerized glycols and trimerized glycols, and / or structural units derived from at least one polyamine from dimericamines and trimerized aminos, and have carbamate bonds, or may have urea bonds (A1). Hereinafter, structures derived from the aforementioned structural units will be collectively referred to as "dimer structures". Carbamate bonds are formed by the reaction of hydroxyl groups with isocyanate groups, and urea bonds are formed by the reaction of amino groups with isocyanate groups. Carbamate resins are obtained by subjecting reactants to carbamate bonding, wherein the reactants include a polyol component having two or more hydroxyl groups in one molecule and a polyisocyanate component having two or more isocyanate groups in one molecule. Carbamate urea resins are, for example, obtained by reacting a carbamate prepolymer of terminal isocyanates obtained by reacting a polyol with a polyisocyanate, and a chain extender such as a polyamine component having two or more amino groups in one molecule.

[0073] By using urethane-based resins (A1) that combine dimer structures with urethane bonds or a combination of dimer structures, urethane bonds, and urea bonds, excellent flexibility and suitable elongation at break of the resin sheet are achieved, resulting in excellent sealing performance. Furthermore, the non-shared electron pairs of nitrogen atoms contained in the urethane bonds prevent cracking or breakage of the sealing layer, achieving not only excellent coating properties but also strong adhesion to the adhered material.

[0074] 1-1b. Polyfunctional maleimide compounds (B)

[0075] Multifunctional maleimide compounds (B) are compounds having two or more maleimide groups and can be represented by the following general formula (1).

[0076] [Chemistry 1]

[0077]

[0078] In equation (1), R 1 For an organic group with a valence of k, R 2 R 3 It can be a hydrogen atom or a monovalent organic group.

[0079] The organic group can be a hydrocarbon group consisting only of C and H, or it can be a group that contains heteroatoms or halogen atoms such as N, O, and S in addition to C and H.

[0080] k is an integer greater than or equal to 2, preferably an integer between 2 and 10.

[0081] R 2 R 3 They can be the same base or different bases.

[0082] In equation (1), R is used as 1 Examples of alkylene groups include alkylene and arylenes. Alkylenes can be groups with 1 to 20 carbon atoms. Alkylenes can be chain-like or cyclic. Chain-like alkylenes can be either straight-chain or branched-chain. Examples of chain-like alkylenes include methylene, ethylene, and hexamethylene. Arylenes can be groups with 1 to 20 carbon atoms. Examples of arylenes include phenylene and methylphenylene.

[0083] In equation (1), R is used as 2 R 3 The organic group can be an alkyl or aryl group having 1 to 20 carbon atoms. Alkyl groups include methyl, ethyl, propyl, etc. Aromatic groups include phenyl, substituted phenyl, naphthyl, substituted naphthyl, etc.

[0084] Examples of such multifunctional maleimide compounds include: N,N'-ethylidene bismaleimide, N,N'-hexamethylene bismaleimide, N,N'-(1,3-phenylene)bismaleimide, N,N'-[1,3-(2-methylphenylene)]bismaleimide, N,N'-(1,4-phenylene)bismaleimide, bis(4-maleimidephenyl)methane, bis(3-methyl-4-maleimidephenyl)methane, bis(4-maleimidephenyl) ether, bis(4-maleimidephenyl) sulfone, bis(4-maleimidephenyl) sulfide, bis(4-maleimidephenyl) ketone, bis(4-maleimidecyclohexyl)methane, and 1,4-bis(4-maleimidephenyl)cyclohexane. 1,4-bis(4-maleimidemethyl)cyclohexane, 1,4-bis(maleimidemethyl)benzene, 1,3-bis(3-maleimidephenoxy)benzene, bis[4-(4-maleimidephenoxy)phenyl]methane, 1,1-bis[4-(3-maleimidephenoxy)phenyl]ethane, 1,1-bis[4-(4-maleimidephenoxy)phenyl]ethane, 1,2-bis[4-(3-maleimidephenoxy)phenyl]ethane, 1,2-bis[4-(4-maleimidephenoxy)phenyl]ethane, 2,2-bis[4-(4-maleimidephenoxy)phenyl]propane, 2,2-bis[4-(3-maleimidephenoxy)phenyl]butane, 2,2-bis[4-(3-maleimide)phenyl]butane, [phenoxy]phenyl]butane, 2,2-bis[4-(3-maleimidephenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-maleimidephenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4'-bis(3-maleimidephenoxy)biphenyl, 4,4'-bis(4-maleimidephenoxy)biphenyl, bis[4-(3-maleimidephenoxy)phenyl]one, bis[4-(4-maleimidephenoxy)phenyl]one, bis[4-(3-maleimidephenoxy)phenyl]sulfide, bis[4-(4-maleimidephenoxy)phenyl]sulfide, bis[4-(3-maleimidephenoxy)phenyl]sulfoxide, bis[4-(4-)- ... [4-(3-maleimidephenoxy)phenyl] sulfoxide, bis[4-(4-maleimidephenoxy)phenyl] sulfoxide, bis[4-(3-maleimidephenoxy)phenyl] sulfoxide, bis[4-(3-maleimidephenoxy)phenyl] ether, bis[4-(4-maleimidephenoxy)phenyl] ether, 1,4-bis[4-(4-maleimidephenoxy)-α,α-dimethylbenzene]benzene, 1,3-bis[4-(4-maleimidephenoxy)-α,α-dimethylbenzene]benzene, 1,4-bis[4-(3-maleimidephenoxy)-α,α-dimethylbenzene]benzene, 1,3-bis[4-(3-maleimidephenoxy)-α,α-dimethylbenzene]benzene, 1,3-bis[4-(3-maleimidephenoxy)-α,α-dimethylbenzene]benzene, 1,4-bis[4-(4-maleimidephenoxy)-3 ...[5-Dimethyl-α,α-dimethylbenzene]benzene, 1,3-bis[4-(4-maleimidephenoxy)-3,5-dimethyl-α,α-dimethylbenzene]benzene, 1,4-bis[4-(3-maleimidephenoxy)-3,5-dimethyl-α,α-dimethylbenzene]benzene, 1,3-bis[4-(3-maleimidephenoxy)-3,5-dimethyl-α,α-dimethylbenzene]benzene, etc.

[0085] In addition, as a multifunctional maleimide compound (B), not only the non-polymers mentioned above can be listed, but also the polymers represented by the following general formulas (2) and (3).

[0086] [Chemistry 2]

[0087]

[0088] [Chemistry 3]

[0089]

[0090] In formulas (2) and (3), n and m represent the number of repeating units, with an average value of 0 to 10. In formulas (2) and (3), methylene is a group bonded to the 2nd or 3rd position of an aromatic ring, and R is one or more substituents bonded at any position where there is no methylene bond. Examples of R include alkyl groups, aryl groups, etc., with 1 to 20 carbon atoms.

[0091] The proportion of the polyfunctional maleimide compound (B) in this composition is preferably 5 to 80 parts by weight relative to 100 parts by weight of the thermosetting resin (A). If the proportion of the polyfunctional maleimide compound (B) is 5 parts by weight or more, the solder crack resistance and heat resistance are superior. From the same viewpoint, the proportion of the polyfunctional maleimide compound (B) is more preferably 10 parts by weight or more, and even more preferably 15 parts by weight or more. Furthermore, if the proportion of the polyfunctional maleimide compound (B) is 80 parts by weight or less, the adhesion is superior. From the same viewpoint, the proportion of the polyfunctional maleimide compound (B) is more preferably 60 parts by weight or less, and even more preferably 40 parts by weight or less.

[0092] 1-1c. Benzoxazine compounds (C)

[0093] Benzoxazine compound (C) is a compound having a benzoxazine ring within its molecule. There is no particular limitation on benzoxazine compound (C), but from the viewpoint of crosslinking properties and hardening properties, compounds having two or more benzoxazine rings within one molecule are preferred. Specific examples of benzoxazine compounds include: Fa-type benzoxazine compounds obtained by reacting bisphenol A-type benzoxazine compounds and bisphenol F-type benzoxazine compounds with an amine compound (e.g., aniline) and formaldehyde; and Pd-type benzoxazine compounds obtained by reacting a phenyldiamine compound with a phenol compound and formaldehyde, such as diaminodiphenylmethane-type benzoxazine compounds.

[0094] These can utilize compounds that are commercially available. Furthermore, these are non-polymers. Among Fa-type and Pd-type benzoxazine compounds, Pd-type benzoxazine compounds are preferred from the viewpoint of superior heat resistance.

[0095] For example, bisphenol F benzoxazine compounds, which are Fa-type benzoxazine compounds, have the structure shown in formula (4). They are compounds obtained by reacting bisphenol F with aniline and formaldehyde.

[0096] [Chemistry 4]

[0097]

[0098] For example, Pd-type benzoxazine compounds have the structure shown in formula (5). These compounds are obtained by reacting 4,4'-methylenediphenylamine with phenol and formaldehyde.

[0099] [Chemistry 5]

[0100]

[0101] The proportion of the benzoxazine compound (C) in this composition is preferably 1 to 50 parts by mass relative to 100 parts by mass of the thermosetting resin (A). If the proportion of the benzoxazine compound (C) is 1 part by mass or more, the flame retardancy can be further improved. From the same viewpoint, the proportion of the benzoxazine compound (C) is more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. Furthermore, if the proportion of the benzoxazine compound (C) is 50 parts by mass or less, the brittleness of the sheet can be mitigated, and the conformability of electronic components can be easily improved. From the same viewpoint, the proportion of the benzoxazine compound (C) is more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0102] 1-1d. Epoxy resin (D)

[0103] Epoxy resin (D) can be any resin containing epoxy groups within its molecule, without particular limitation. To improve the heat resistance or adhesion of the coating, multifunctional epoxy resins with trifunctionality or higher are useful. When coating flexibility is required, difunctional epoxy resins such as bisphenol A and bisphenol F (described later) are useful. Epoxy resin (D) may consist solely of trifunctional epoxy resins, or may include a combination of trifunctional epoxy resins and difunctional or monofunctional epoxy resins.

[0104] Examples of epoxy resins (D) include: bisphenol type epoxy resins, triphenylmethane type epoxy resins, phenolic varnish type epoxy resins, alicyclic epoxy resins, glycidyl esters, glycidyl amines, heterocyclic epoxy resins, brominated epoxy resins, etc.

[0105] Examples of bisphenol-type epoxy resins include: bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin.

[0106] Examples of phenylmethane-type epoxy resins include diphenylmethane-type epoxy resins and triphenylmethane-type epoxy resins.

[0107] Examples of phenolic varnish-type epoxy resins include: phenolic varnish-type epoxy resin, cresol varnish-type epoxy resin, bisphenol A varnish-type epoxy resin, and dicyclopentadiene varnish-type epoxy resin.

[0108] Examples of alicyclic epoxy resins include: 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexane carboxylate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, and 1-epoxyethyl-3,4-epoxycyclohexane.

[0109] Examples of glycidyl esters include: diglycidyl phthalate, tetrahydrodiglycidyl phthalate, and dimeric glycidyl esters.

[0110] Examples of glycidylamines include tetraglycidyldiaminodiphenylmethane, triglycidylp-aminophenol, and N,N-diglycidylaniline.

[0111] Examples of heterocyclic epoxy resins include 1,3-diglycidyl-5,5-dimethylhydantoin and triglycidyl isocyanurate.

[0112] Examples of brominated epoxy resins include: tetrabromobisphenol A type epoxy resin, tetrabromobisphenol F type epoxy resin, brominated cresol phenolic varnish type epoxy resin, brominated phenol phenolic varnish type epoxy resin, etc.

[0113] The epoxy resin (D) in this composition is preferably 1 to 50 parts by weight relative to 100 parts by weight of the thermosetting resin (A). If the epoxy resin (D) content is 1 part by weight or more, the adhesion is superior. From the same viewpoint, the epoxy resin (D) content is more preferably 3 parts by weight or more, and even more preferably 5 parts by weight or more. Furthermore, if the epoxy resin (D) content is 50 parts by weight or less, the protection of electronic components is superior. From the same viewpoint, the epoxy resin (D) content is more preferably 45 parts by weight or less, and even more preferably 40 parts by weight or less.

[0114] Relative to 100 parts by weight of the thermosetting resin (A), the total content of the polyfunctional maleimide compound (B), benzoxazine compound (C), and epoxy resin (D) in this composition is preferably 5 to 180 parts by weight. If the total content of these components is 5 parts by weight or more, the solder crack resistance and adhesion are superior. From the same viewpoint, the total content of these components is more preferably 10 parts by weight or more, more preferably 20 parts by weight or more, and particularly preferably 60 parts by weight or more. Furthermore, if the total content of these components is 180 parts by weight or less, the resin flakes can be easily prevented from entering the hollow portion, resulting in superior adhesion. From the same viewpoint, the total content of these components is more preferably 160 parts by weight or less, more preferably 140 parts by weight or less, particularly preferably 120 parts by weight or less, and most preferably 100 parts by weight or less.

[0115] Furthermore, components (B) to (D) can also be mixed with other components (e.g., thermosetting resin (A)) in a pre-mixed state. Additionally, heat (e.g., above 100°C) can be applied and melt-mixed at this time.

[0116] 1-1e. Other ingredients

[0117] Inorganic filler (E)

[0118] This composition may contain inorganic fillers (E) such as metal oxides. Examples of inorganic fillers (E) include: silicon dioxide, aluminum oxide, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, talc, kaolinite, mica, basic magnesium carbonate, sericite, montmorillonite, bentonite, boron nitride, aluminum nitride, titanium nitride, carbon black, and other inorganic compounds.

[0119] From the viewpoint of coating resistance to scratches, titanium oxide, titanium nitride, silicon dioxide, talc, mica, kaolinite, or montmorillonite are preferred, titanium oxide, titanium nitride, and silicon dioxide are more preferred, and silicon dioxide is particularly preferred. In this composition, silicon dioxide is particularly preferably contained in the form of particle-shaped silicon dioxide particles. In this disclosure, from the viewpoint of coating resistance, two or more inorganic fillers may also be included.

[0120] The average primary particle size (hereinafter, particle size) of the inorganic filler (E) is preferably 0.1 μm to 50 μm. By setting the particle size to 0.1 μm or more, it is easier to maintain the viscosity of the resin composition at a level suitable for coating. In addition, by setting the particle size to 50 μm or less, the smoothness of the coating film is further improved. Furthermore, the particle size of the inorganic filler (E) can be determined based on the average value of about 20 primary particles that can be observed in an image magnified to about 50,000 to 1,000,000 times using a transmission electron microscope (TEM).

[0121] The inorganic filler (E) can also be mixed with the thermosetting resin (A) after mechanical disintegration, and the mixture can be further dispersed. The dispersion treatment preferably uses a dispersant. The dispersant imparts repulsive forces between the inorganic fillers, preventing the dispersed inorganic fillers from re-aggregating.

[0122] As dispersants, existing known compounds can be used. Examples include: polymeric dispersants, pigment derivative dispersants, or surfactants selected from cationic, anionic, or nonionic systems. The Mw of these dispersants is, for example, around 1,000 to 30,000.

[0123] The content of inorganic filler (E) in this composition (solid component) is preferably 5% to 70% by mass. If the content of inorganic filler (E) is 5% by mass or more, it is easier to prevent resin flakes from entering the hollow portion, thereby improving solder crack resistance. From the same viewpoint, the content of inorganic filler (E) is more preferably 10% by mass or more. Furthermore, if the content of inorganic filler (E) is 70% by mass or less, the adhesion and solder crack resistance are even better. From the same viewpoint, the content of inorganic filler (E) is more preferably 60% by mass or less.

[0124] To adjust the crosslinking rate during the curing process or the physical properties of the resin sheets, this composition may also contain a curing accelerator. There are no particular limitations on the curing accelerator; it can be selected appropriately. Specific examples of curing accelerators include: amine-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. These can be used alone or in combination of two or more.

[0125] From the viewpoint of application suitability, the content of the curing accelerator in this composition (solid component) is preferably 0.01% to 10% by mass, more preferably 0.1% to 5% by mass.

[0126] This composition can further be supplemented with various additives without departing from the spirit of this disclosure. For example, thermally conductive fillers may be exemplified. Furthermore, antistatic agents, flame retardants, antioxidants, UV stabilizers, colorants, dispersants, surface conditioning additives, curing delay agents, softeners, anti-caking agents, adhesion modifiers, embedment modifiers, and other additives may be suitably added.

[0127] 2. Hollow electronic components

[0128] like Figure 1 As shown in (a), the hollow electronic component 10 of this disclosure (hereinafter also referred to as the hollow electronic component) includes: a substrate 1; an electronic component 2 mounted on the substrate 1; and a sealing layer 4 that seals the electronic component 2 while maintaining the hollow structure 3 between the substrate 1 and the electronic component 2. Here, in the hollow electronic component, the sealing layer 4 is formed from a hardened resin sheet for sealing the hollow electronic component of the present disclosure.

[0129] The manufacturing method of this hollow electronic component is not particularly limited, and existing known methods can be applied. By using this resin sheet, multiple electronic components 2, such as semiconductor elements, can be uniformly coated and mounted on the substrate 1 while maintaining the hollow structure 3. Specifically, the resin sheet is temporarily attached to the sides of the multiple electronic components 2, and the resin sheet is heated and / or pressurized to soften it. While maintaining the hollow structure 3, the resin sheet covers the upper surface of the substrate 1 and the upper and side surfaces of the multiple electronic components 2 and is then bonded. The resin sheet is then hardened to form a sealing layer 4 that seals the electronic components 2, thereby obtaining the hollow electronic component.

[0130] At this time, the resin sheet can be a single layer or multiple layers of the resin sheet disclosed herein. Additionally, as... Figure 1 As shown in (b), the hollow electronic component can also have a second sealing layer 5, such as ingot-shaped, liquid-shaped, granular, or sheet-shaped, coated on the sealing layer (first sealing layer) 4 formed from the hardened resin sheet, to perform secondary sealing of the substrate 1 and the electronic component 2. Thus, in the hollow electronic component, multiple sealing layers can be used to seal the electronic component 2.

[0131] [Example]

[0132] The present disclosure is described in detail below through embodiments and comparative examples, but the present disclosure is not limited to the embodiments. In addition, unless otherwise specified, "parts" and "%" in the following description refer to "parts by mass" and "% by mass", respectively.

[0133] 1. Resin sheet for sealing hollow electronic components (hereinafter, resin sheet)

[0134] The following shows the raw materials used in each example.

[0135] 1-1. Thermosetting resin (A)

[0136] Synthesis of thermosetting resin a1

[0137] [Synthesis of Polyester Diol]

[0138] In a glass flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet pipe, and pressure reducing apparatus, 266 parts of terephthalic acid, 30 parts of adipic acid, 212 parts of 3-methyl-1,5-pentanediol, and 25 parts of ethylene glycol were added, and the mixture was stirred while being purged with nitrogen gas. The mixture was slowly heated under normal pressure and reacted at 200℃–230℃ for approximately 8 hours to obtain a liquid with an acid value of 43 mg KOH / g. Then, 0.01 parts of tetra-n-butoxytitanium were added, and after nitrogen purging, the mixture was stirred at 180℃ for 30 minutes under a sealed environment. Subsequently, the mixture was reacted at 230℃ and 5 mmHg for 2 hours to obtain a polyester glycol with an acid value of 1.1 mg KOH / g, a hydroxyl value of 114.2 mg KOH / g, and a molecular weight of 982. In addition, the acid value and hydroxyl value are determined by weighing the thermosetting resin and measuring it according to the potentiometric titration method of Japanese Industrial Standards (JIS) K0070 using an automatic titration device GT-200 (trade name) manufactured by Mitsubishi Chemical Analytech Co., Ltd., and by converting the solid composition.

[0139] Synthesis of carbamate prepolymers

[0140] Subsequently, in a reaction vessel including a stirrer, thermometer, reflux cooler, dropping device, and nitrogen inlet pipe, 734 parts of the polyester diol, 23.9 parts of dimethylolpropionic acid, 219 parts of toluene diisocyanate, and 242 parts of toluene were added, and the mixture was reacted at 50°C for 8 hours under nitrogen atmosphere. Then, 1200 parts of toluene were added to obtain a urethane prepolymer solution with isocyanate groups at the ends.

[0141] [Synthesis of Carbamate Polymers]

[0142] Next, the obtained urethane prepolymer solution was heated to 70°C, and while maintaining this temperature, a solution consisting of 20.0 parts of 1,3-diaminopropane, 600 parts of 2-propanol, and 961 parts of toluene was added dropwise over a period of 1 hour. After the addition was completed, the mixture was further reacted at 70°C for 6 hours to obtain a polyurethane resin (thermosetting resin a1) with a molecular weight (Mw) of 130,000, an acid value of 10 mgKOH / g, a Tg of 20°C, and a solids content of 25%.

[0143] 1-2. Maleimide complex (a mixture of components (B) to (D))

[0144] [Preparation of maleimide complex compounds m1 to m4]

[0145] The following compounds are prepared as maleimide complexes comprising a multifunctional maleimide compound (B) having two or more maleimide groups, a benzoxazine compound (C) and an epoxy resin (D).

[0146] Maleimide complex m1: "HR3053 (trade name)", manufactured by Printec Corporation.

[0147] Maleimide complex m2: “HR-YSP (trade name)”, manufactured by Printec Corporation.

[0148] Maleimide complex m3: "HR3070 (trade name)", manufactured by Printec Corporation.

[0149] Maleimide complex m4: "HR3072 (trade name)", manufactured by Printec Corporation.

[0150] 1-3. Epoxy Resin (D)

[0151] [Preparation of epoxy resin d1 to epoxy resin d3]

[0152] The following compounds are prepared as epoxy resins.

[0153] Epoxy resin d1: Trifunctional epoxy compound "VG3101L (trade name)", epoxy equivalent 210 g / eq, manufactured by Printec Corporation.

[0154] Epoxy resin d2: a difunctional epoxy compound, "Epiclon 840 (trade name)", with an epoxy equivalent of 190 g / eq, containing hydroxyl groups, manufactured by DIC Corporation.

[0155] Epoxy resin d3: Phenolic varnish-type epoxy compound "MEH-7851-SS (trade name)", epoxy equivalent 105 g / eq, manufactured by Nippon Kayaku Co., Ltd.

[0156] 1-4. Adding materials

[0157] Prepare the following compounds as additives.

[0158] Additive f1: Carbodilite V-01 (trade name), a carbodiimide compound, with an epoxy equivalent of 105 g / eq, manufactured by Nisshinbo Chemical Co., Ltd.

[0159] Additive f2: Imidazole compound "Curezol 2E4MZ (trade name)", manufactured by Shikoku Chemical Co., Ltd.

[0160] Additive F3: Silane coupling agent "KBM403 (trade name)", manufactured by Shin-Etsu Chemical Industry Co., Ltd.

[0161] 1-5. Inorganic fillers (E)

[0162] [Preparation of Inorganic Filler E1 and Inorganic Filler E2]

[0163] The following compounds are prepared as inorganic fillers.

[0164] Inorganic filler e1: "Hipresica TSN3N (trade name)", D 50 =2.0 μm, manufactured by Ube Exsymo Co., Ltd.

[0165] Inorganic filler e2: "Mitsubishi Carbon Black MA-8 (trade name)", D 50 =24 nm, manufactured by Mitsubishi Chemical Corporation

[0166] 2. Measurement Method

[0167] 2-1. Elongation at break

[0168] The resin sheets with release films obtained by the methods described later in each embodiment and comparative example were cut into sizes of 20 mm wide × 60 mm long. The release film was then peeled off, thereby obtaining test specimens (electronic component coating sheets). The test specimens were placed at a temperature of 100°C (atmosphere, 50% RH), and after 1 minute at the stated temperature, a tensile test was performed using a small benchtop testing machine, EZ-TEST (trade name, manufactured by Shimadzu Corporation), at a tensile speed of 50 mm / min, with an effective tensile dimension of 20 mm × 17 mm, and the elongation at break (%) was determined.

[0169] 2-2. Coefficient of linear expansion (CTE)

[0170] The resin sheets with release films from each example and comparative example were cured at 180°C for 2 hours, and the release films were then peeled off. The sheets were cut into pieces 4 mm wide and 20 mm long. Using a TMA Q400 instrument manufactured by TA Instruments, the displacement was measured when a heating load of 1 g was applied at a heating rate of 6°C / min from 0°C to 300°C. The coefficient of linear expansion was determined by averaging the slopes between 150°C and 200°C when the sample temperature was plotted on the horizontal axis and the displacement on the vertical axis.

[0171] 2-3. Adhesive strength

[0172] The resin sheets with release films obtained by the method described later for each embodiment and comparative example were cut into 90 mm × 90 mm sizes. Additionally, two polyimide films of the same size and 50 μm thickness ("Kapton 200EN" (trade name) manufactured by Toray DuPont Co., Ltd.) were prepared. Then, the release films of the electronic component coverslips in each example were peeled off, and the polyimide films were temporarily bonded sequentially to both sides of the electronic component coverslips at 90°C, 0.3 MPa, and 1 m / min. Afterward, they were hot-pressed at 100°C, 1.0 MPa, and 3 min, followed by a curing treatment at 180°C for 2 hours. Test pieces with a width of 10 mm and a length of 90 mm were cut from the hardened specimens. A 90-degree peel test was conducted at a tensile speed of 50 mm / min using a small benchtop testing machine EZ-TEST (trade name, manufactured by Shimadzu Corporation) at 25°C and 50%RH to determine the adhesive strength A (N / cm).

[0173] 2-4. Glass transition temperature Tg

[0174] According to JIS K7198, the Tg of the test specimens (electronic component coated sheets) of each example and comparative example were measured using a dynamic viscoelasticity measuring device DVA-200 (trade name, manufactured by IT Measurement & Control Co., Ltd.). The following items were used in the measurement: resin sheets with release films from each example were cured at 180°C for 2 hours, cut into 0.5 cm × 3 cm pieces, and the release film was peeled off. The deformation mode was tension, and the loss tangent was measured at a strain of 0.08%, a frequency of 10 Hz, a heating rate of 10°C / min, and a temperature range of -50°C to 300°C. The temperature at which the main dispersion peak appears is set as Tg. Furthermore, in multilayer coated sheets, there are sometimes multiple loss tangents (…). The maximum value of ) is set to the highest temperature, which is then set as the Tg (°C) of the sample.

[0175] 3. Preparation of resin sheets

[0176] [Example 1]

[0177] 100 parts of thermosetting resin a1 (solid component), 3 parts of maleimide composite compound m1 (HR3053), 0.8 parts of additive f1 (Carbodilite V-01), 0.1 parts of additive f2 (2E4MZ), 45 parts (30% by mass) of inorganic filler e1, and 0.8 parts (0.5% by mass) of inorganic filler e2 were loaded into a container. Toluene was then added to the container at a non-volatile component concentration of 33% by mass, and the mixture was stirred for 10 minutes using a disperser to obtain the composition. The composition was then applied to a release film (a 50 μm thick polyethylene terephthalate film after demolding) to a dry thickness of 20 μm using a doctor blade. The film was then dried at 100°C for 2 minutes to obtain a single-layer (first layer) resin sheet with a release film.

[0178] [Examples 2-24, Comparative Example 1, Comparative Example 2]

[0179] Except for changes to the formulation of the composition as described in Tables 1 and 2, resin sheets with release films of Examples 2 to 24, Comparative Example 1 and Comparative Example 2 were obtained using the same method as in Example 1.

[0180] The formulations of each embodiment and comparative example are shown in Tables 1 and 2 below.

[0181] [Table 1]

[0182] Table 1

[0183]

[0184] [Table 2]

[0185] Table 2

[0186]

[0187] 4. Preparation of the experimental substrate with SAW chip (hereinafter, experimental substrate 20)

[0188] A test substrate 20 is prepared on an FR-4 substrate (80 mm in length, 80 mm in width, and 0.25 mm in height) containing glass epoxy resin, on which SAW chips (1.2 mm in length, 1.2 mm in width, and 0.2 mm in height) as electronic components are mounted in 5 columns and 5 rows with a mounting interval of 0.2 mm (200 μm). The SAW chips are bonded to the FR-4 substrate using lead-free solder balls 13 (50 μm in height). The solder balls 13 are positioned 0.1 mm inside the SAW chip from its end, and the four corners of the SAW chip are bonded to the FR-4 substrate under bonding conditions at 200°C (see reference). Figure 2 of (a) Figure 2 (b)). Furthermore, Figure 2 of (a) Figure 2 (b) is a schematic diagram of the experimental substrate of this embodiment. Figure 2 (a) represents its top view (plan view). Figure 2 (b) represents the front cross-sectional view.

[0189] 5. Evaluation

[0190] The resin sheets with release films of each embodiment and comparative example were arranged on a test substrate with the resin sheet side of the resin sheet having a release film attached. After hot pressing at 100°C, 0.1 MPa, and 1 min, the release film was peeled off, and then hot pressing was performed again at 100°C, 0.5 MPa, and 3 min. The substrate was heated at 180°C for 2 hours to obtain a test substrate coated with a resin sheet (test substrate with resin sheet). The obtained test substrate with resin sheet was evaluated as follows.

[0191] 5-1. SAW chip protection

[0192] A cross-section of a test substrate with a resin sheet was formed by grinding to allow observation of the resin sheet's coating of the SAW chip and its insertion into the hollow portion of the SAW. Ten SAW chips were randomly selected and observed using an electron microscope (400x magnification). The protective properties of the SAW chips were determined according to the following criteria.

[0193] 5-1-1. SAW chip coverage

[0194] Observe the coating state of the resin sheet on the SAW chip, count the number of SAW chips that are completely coated by the resin sheet, and evaluate them according to the following criteria.

[0195] Evaluation Criteria

[0196] A: The number of SAW chips coated with resin sheets is 10.

[0197] B: The number of SAW chips coated with resin sheets is 8 to 9.

[0198] C: The number of SAW chips coated with resin sheets is 6 to 7.

[0199] D: The number of SAW chips coated with resin sheets is 4 to 5.

[0200] E: The number of SAW chips coated with resin sheets is 3 or less. Not practical.

[0201] 5-1-2. SAW Hollow Section Accessibility

[0202] Observe the entry state of the resin sheet into the hollow part of the SAW chip, count the number of SAW chips whose solder balls at the bottom of the SAW chip are in contact with the resin sheet, and evaluate according to the following criteria.

[0203] Evaluation Criteria

[0204] A: The number of SAW chips in contact with the solder balls is 0.

[0205] B: The number of SAW chips in contact with the resin sheet and solder balls is 1 to 2.

[0206] C: The number of SAW chips in contact with the resin sheet and solder balls is 3 to 4.

[0207] D: The number of SAW chips in contact with the resin sheet and solder balls is 5 to 6.

[0208] E: The number of SAW chips in contact with the resin sheet and solder balls is 7 or more. Not suitable for practical use.

[0209] 5-2. Solder crack resistance after thermal shock testing

[0210] The test substrate with the resin sheet was placed in a thermal shock apparatus TSA-43EL (trade name, manufactured by ESPEC) and subjected to 1000 cycles of thermal shock testing at various temperatures, with an exposure time of 10 minutes at each temperature, ranging from -50°C to 125°C. A cross-section of the test substrate with the resin sheet was formed after the test by grinding to allow observation of the state of the solder balls at the bottom of the SAW chip. For any 10 SAW chips, observation was performed using an electron microscope (400x magnification), and the cracks appearing in the solder balls at the bottom of the SAW chips were judged according to the following criteria.

[0211] Evaluation Criteria

[0212] A: The number of SAW chips with cracks in the solder balls is 0.

[0213] B: The number of SAW chips with cracks in the solder ball is 1 to 2.

[0214] C: The number of SAW chips with cracks in the solder ball is 3 to 4.

[0215] D: The number of SAW chips with cracks in the solder balls is 5 to 6.

[0216] E: The number of SAW chips with cracks in the solder balls is 7 or more. Not suitable for practical use.

[0217] 5-3. Adhesion after thermal shock test

[0218] The test substrate with the resin sheet was placed in a thermal shock apparatus TSA-43EL (trade name, manufactured by ESPEC) and subjected to 1000 cycles of thermal shock testing at various temperatures, with an exposure time of 10 minutes at each temperature, ranging from -50°C to 125°C. A cross-section of the test substrate with the resin sheet was formed after the test by grinding to allow observation of the bonding state between the resin sheet and the SAW chip. For any 10 SAW chips, observation was performed using an electron microscope (400x magnification), and the delamination state between the resin sheet and the SAW chip was determined according to the following criteria.

[0219] Evaluation Criteria

[0220] A: The number of SAW chips that caused the resin sheet to peel off is 0.

[0221] B: The number of SAW chips that cause the resin sheet to peel off is 1 to 2.

[0222] C: The number of SAW chips that cause the resin sheet to peel off is 3 to 4.

[0223] D: The number of SAW chips that cause the resin sheet to peel off is 5 to 6.

[0224] E: The number of SAW chips that cause resin sheet peeling is 7 or more. Not practical.

[0225] The physical properties and evaluation results of each embodiment and comparative example are shown in Tables 3 and 4 below.

[0226] [Table 3]

[0227] Table 3

[0228]

[0229] [Table 4]

[0230] Table 4

[0231]

[0232] In Comparative Example 2, which does not contain thermosetting resin (A), or Comparative Examples 1 and 2, which do not contain polyfunctional maleimide compound (B) and benzoxazine compound (C), issues were identified regarding SAW chip protection or adhesion after thermal shock testing due to poorer flexibility or adhesion compared to other examples. That is, it was found that in these comparative examples, it was difficult to achieve both excellent flexibility and low thermal expansion.

[0233] On the other hand, the SAW chip protection of this resin sheet, which contains thermosetting resin (A), a multifunctional maleimide compound (B), a benzoxazine compound (C), and epoxy resin (D), is excellent. Furthermore, the solder crack resistance and adhesion after thermal shock testing are also good. In addition, the evaluation results for all items of the resin sheets shown in Examples 6 to 8 and Examples 13 to 15 were confirmed to be A, which is particularly excellent.

[0234] Furthermore, this disclosure is not limited to the described embodiments, and can be appropriately modified without departing from the spirit of the matter. Additionally, this disclosure can also be implemented by combining the described embodiments or examples thereof.

Claims

1. A resin sheet for sealing hollow electronic components, which is a resin sheet used to form a sealing layer for sealing hollow electronic components. The resin sheet is a resin composition comprising a polyurethane resin, a multifunctional maleimide compound (B) having two or more maleimide groups, a benzoxazine compound (C), and an epoxy resin (D).

2. The resin sheet for sealing hollow electronic components according to claim 1, wherein, Relative to 100 parts by weight of the polyurethane resin, the total content of the polyfunctional maleimide compound (B) having two or more maleimide groups, the benzoxazine compound (C), and the epoxy resin (D) in the resin composition is 5 to 180 parts by weight.

3. The resin sheet for sealing hollow electronic components according to claim 1, wherein, The resin composition further comprises an inorganic filler (E) comprising silica particles.

4. The resin sheet for sealing hollow electronic components according to claim 3, wherein, The content of inorganic filler (E) in the resin composition is 5% to 70% by mass.

5. The resin sheet for sealing hollow electronic components according to claim 1, wherein, The coefficient of linear expansion of the cured material obtained by curing the resin sheet at 180°C for 2 hours is 3 ppm / K to 750 ppm / K at 150°C to 200°C.

6. The resin sheet for sealing hollow electronic components according to claim 1, wherein, The elongation at break at 100℃ is 300% to 2000%.

7. The resin sheet for sealing hollow electronic components according to claim 1, wherein, The cured product, formed by bonding the resin sheet to a polyimide substrate and curing it at 180°C for 2 hours, has an adhesion strength of 0.6 N / cm to 40 N / cm at 25°C.

8. A hollow electronic component, comprising: substrate; Electronic components are mounted on the substrate; And a sealing layer that seals the electronic component while maintaining the hollow structure between the substrate and the electronic component, the sealing layer being formed from a hardened resin sheet for sealing hollow electronic components as described in any one of claims 1 to 7.

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