Resin sheet for sealing and electronic element package

Abstract

To provide a resin sheet for sealing and an electronic element package which can suppress warpage of an electronic element package containing a resin sheet for sealing after curing, while suppressing contamination of its periphery by a second layer, in hot pressing and after curing.SOLUTION: A resin sheet 1 for sealing includes a first layer 11, and a second layer 12 in this order in a thickness direction. When the resin sheet 1 for sealing seals an electronic element 3, the first layer 11 is brought into contact with the electronic element 3. The first layer 11 and the second layer 12 contain a thermosetting component, respectively. The second layer 12 further contains a thermoplastic component and a filler. A blending ratio of the filler in the second layer 12 is 30 mass% or more and 60 mass% or less. Viscosity at 70°C of the second layer 12 is more than 35 kPa s or more and 150 kPa s or less. Tensile storage elastic modulus E' at 25°C of the second layer 12 after curing is 0.5 GPa or more and 2.3 GPa or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sealing resin sheet and an electronic element package. [Background technology]

[0002] The sealing resin sheet is used, for example, to seal electronic elements. A sealing resin sheet is known that has a first layer and a second layer toward one side in the thickness direction, and when the sealing resin sheet seals the electronic element, the first layer comes into contact with the electronic element and the second layer is exposed to the outside (for example, see Patent Document 1 below).

[0003] In the sealing resin sheet described in Patent Document 1, each of the first layer and the second layer contains a thermosetting component, a thermoplastic component, and a filler.

[0004] In Patent Document 1, a sealing resin sheet is heat-pressed against a mounting substrate on which electronic elements are mounted to seal the electronic elements with the sealing resin sheet, and then the sealing resin sheet is cured to form a sealing layer, thereby producing a laminate (package) including the mounting substrate and the sealing layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-103721 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the laminate, the sealing layer is hard, and there is a problem that the laminate is easily warped.

[0007] Therefore, a tentative attempt has been made to reduce the warpage of the laminate by reducing the mixing ratio of the filler in the sealing layer, particularly the mixing ratio of the filler in the second layer exposed to the outside. With this tentative plan, the second layer becomes soft after curing, which is thought to contribute greatly to reducing the warpage of the laminate.

[0008] However, when an electronic element is sealed with the sealing resin sheet, i.e., when the sealing resin sheet is heated, the second layer of the above-mentioned trial solution tends to flow excessively, causing a problem that the surrounding components are contaminated by the second layer.

[0009] On the other hand, it is also necessary to prevent the second layer from contaminating the surrounding members even after curing.

[0010] The object of the present invention is to provide a sealing resin sheet and an electronic element package that can suppress contamination of the surroundings by the second layer during heat pressing and after curing, while reducing warping of an electronic element package including the cured sealing resin sheet. [Means for solving the problem]

[0011] The present invention [1] is an encapsulating resin sheet for encapsulating an electronic element, the encapsulating resin sheet comprising a first layer and a second layer in this order in a thickness direction, the first layer contacting the electronic element when the encapsulating resin sheet encapsulates the electronic element, each of the first layer and the second layer containing a thermosetting component, the second layer further containing a thermoplastic component and a filler, the blending ratio of the filler in the second layer being 30 mass % or more and 60 mass % or less, the viscosity of the second layer at 70°C being more than 35 kPa s and 150 kPa s or less, and the tensile storage modulus E' at 25°C, as determined by dynamic viscoelasticity measurement of the second layer after curing at a heating rate of 10°C / min, a frequency of 1 Hz, and a tensile mode, is 0.5 GPa or more and 2.3 GPa or less.

[0012] The present invention [2] includes the sealing resin sheet according to [1], wherein the blending ratio of the thermoplastic component to the total amount of the thermosetting component and the thermoplastic component in the second layer is 25 mass% or more and 55 mass% or less.

[0013] The present invention [3] includes the encapsulating resin sheet according to [1] or [2], wherein the thermosetting component in the second layer includes an epoxy resin, a phenolic resin, and a curing accelerator.

[0014] The present invention [4] includes the encapsulating resin sheet according to [3], wherein the viscosity of the epoxy resin at 150°C is 0.1 Pa·s or more, and the viscosity of the phenol resin at 150°C is 0.2 Pa·s or more.

[0015] The present invention [5] includes the sealing resin sheet according to [3] or [4], wherein a blending ratio of the total amount of the epoxy resin and the phenol resin to the total amount of the thermosetting component and the thermoplastic component in the second layer is 48 mass% or more and 69 mass% or less.

[0016] The present invention [6] includes an electronic element package comprising: an electronic element; a mounting board on which the electronic element is mounted; and a sealing layer which is a cured product of the sealing resin sheet according to any one of [1] to [5], the sealing layer sealing the electronic element and contacting the mounting board and one side of the electronic element in a thickness direction, wherein the thickness of the electronic element is 200 μm or less, the thickness of the mounting board is 125 μm or less, and the thickness of the sealing layer disposed on one side of the electronic element in the thickness direction is 100 μm or less. Effect of the Invention

[0017] In this sealing resin sheet, the viscosity of the second layer at 70° C. is greater than 35 kPa·s and less than 150 kPa·s, so that contamination of the surroundings by the second layer can be suppressed during heat pressing and even after curing.

[0018] In this encapsulating resin sheet, the tensile storage modulus E' of the second layer after curing is 2.3 GPa or less, so that warping of an electronic element package including the encapsulating resin sheet after curing can be reduced. [Brief description of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view of one embodiment of an encapsulating resin sheet of the present invention. [Diagram 2] FIG. 2 is a manufacturing process diagram of a sealing resin sheet. [Diagram 3] 1 is a cross-sectional view of one embodiment of an electronic device package of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 1. Sealing resin sheet One embodiment of the encapsulating resin sheet of the present invention will be described with reference to FIGS.

[0021] The encapsulating resin sheet 1 shown in FIG. 1 is used to encapsulate an electronic element 3 shown in FIG. 3. Specifically, the encapsulating resin sheet 1 is an electronic element encapsulating sheet for encapsulating the electronic element 3 to produce an electronic element package 5. This encapsulating resin sheet 1 is not the electronic element package 5, nor is it the encapsulating layer 4 after encapsulating the electronic element 3. The encapsulating resin sheet 1 is a precursor (before complete curing) sheet for forming the encapsulating layer 4, which is a part of the electronic element package 5, and does not include the electronic element 3. More specifically, the encapsulating resin sheet 1 is a device that is distributed as a component alone and is industrially applicable.

[0022] As shown in Fig. 1, the encapsulating resin sheet 1 extends in a planar direction. The planar direction is perpendicular to the thickness direction of the encapsulating resin sheet 1. The encapsulating resin sheet 1 includes a first layer 11 and a second layer 12 in this order in the thickness direction. Preferably, the encapsulating resin sheet 1 includes only the first layer 11 and the second layer 12. In the encapsulating resin sheet 1, the first layer 11 and the second layer 12 are arranged in this order toward one side in the thickness direction.

[0023] 1.1 First layer11 3, when the encapsulating resin sheet 1 encapsulates the electronic element 3, the first layer 11 comes into contact with the electronic element 3. That is, the first layer 11 is an electronic element embedding layer. The first layer 11 includes the other surface of the encapsulating resin sheet 1 in the thickness direction. The first layer 11 extends in the planar direction.

[0024] 1.1.1 Components of the first layer 11 The first layer 11 includes a thermosetting component. Examples of the thermosetting component include epoxy resin, melamine resin, vinyl ester resin, cyanoester resin, maleimide resin, and silicone resin. The thermosetting component is preferably an epoxy resin from the viewpoint of increasing affinity with the epoxy resin of the second layer 12 described below, that is, increasing adhesion between the first layer 11 and the second layer 12.

[0025] Examples of the epoxy resin include bifunctional epoxy resins and trifunctional or higher epoxy resins. Examples of the bifunctional epoxy resin include bisphenol A type epoxy resins, bisphenol F type epoxy resins, modified bisphenol A type epoxy resins, modified bisphenol F type epoxy resins, and biphenyl type epoxy resins. Examples of the trifunctional or higher epoxy resins include phenol novolac type epoxy resins, cresol novolac type epoxy resins, trishydroxyphenylmethane type epoxy resins, tetraphenylolethane type epoxy resins, and dicyclopentadiene type epoxy resins. Examples of the epoxy resin include preferably bifunctional epoxy resins, more preferably bisphenol F type epoxy resins.

[0026] The viscosity of the epoxy resin at 150° C. is, for example, less than 0.02 Pa·s, preferably 0.01 Pa·s or less, and for example, 0.001 Pa·s or more, preferably 0.003 Pa·s or more. Catalog values ​​are used as the viscosity of the epoxy resin.

[0027] The epoxy resin is in a solid or liquid state at 25° C. (room temperature). Preferably, the epoxy resin is in a solid state at 25° C. If the epoxy resin of the first layer 11 is in a solid state at 25° C., the first layer 11 has excellent sealing reliability for the electronic element 3.

[0028] The blending ratio of the epoxy resin in the first layer 11 is, for example, 1 mass % or more, preferably 5 mass % or more, and for example, 25 mass % or less, preferably 10 mass % or less. The blending ratio of the epoxy resin in the thermosetting component is, for example, 40 mass % or more, preferably 60 mass % or more, and for example, 90 mass % or less, preferably 70 mass % or less.

[0029] Epoxy resins, for example, are included in the thermosetting component along with phenolic resins and curing accelerators.

[0030] The phenolic resin is an epoxy resin curing agent that cures the epoxy resin. Examples of the phenolic resin include phenolic novolac resin, phenolic aralkyl resin, triphenylmethane novolac resin, cresol novolac resin, and biphenyl type phenolic resin. These may be used in combination. Examples of the novolac resin include preferably phenolic novolac resin and triphenylmethane type phenolic resin. As the novolac resin, preferably, a phenol novolac resin and a triphenylmethane type phenol resin are used in combination.

[0031] The phenol resin is in a solid or liquid state at 25° C. Preferably, the phenol resin is in a solid state at 25° C. If the phenol resin of the first layer 11 is in a solid state at 25° C., the first layer 11 will have excellent sealing reliability for the electronic element 3.

[0032] The viscosity of phenolic resin at 150°C is, for example, 0.01 Pa·s or more and 0.5 Pa·s or less. The catalog value is used as the viscosity of phenolic resin.

[0033] The equivalent of the hydroxyl group in the phenol resin relative to 1 equivalent of the epoxy group in the epoxy resin is, for example, 0.7 equivalents or more, preferably 0.9 equivalents or more, and, for example, 1.5 equivalents or less, preferably 1.2 equivalents or less. The blending ratio of the phenol resin to 100 parts by mass of the epoxy resin is, for example, 20 parts by mass or more, preferably 40 parts by mass or more, and, for example, 80 parts by mass or less, preferably 60 parts by mass or less.

[0034] The curing accelerator is a catalyst (thermosetting catalyst) that accelerates the curing of an epoxy resin by heating. Examples of the curing accelerator include imidazole compounds, organic phosphorus compounds, and urea compounds. Examples of the curing accelerator include a urea compound. Examples of the urea compound include aliphatic dimethylurea. The blending ratio of the curing accelerator to 100 parts by mass of the epoxy resin is, for example, 0.1 parts by mass or more, and, for example, 10 parts by mass or less.

[0035] The blending ratio of the thermosetting component in the first layer 11 (when the thermosetting component contains an epoxy resin, the total of the epoxy resin, the phenolic resin and the curing accelerator) is, for example, 5 mass% or more, preferably 10 mass% or more, and for example, 25 mass% or less, preferably 15 mass% or less.

[0036] In addition to the thermosetting component, the first layer 11 may also contain a thermoplastic component, a filler, and an additive.

[0037] The thermoplastic component may be a thermoplastic resin. Examples of the thermoplastic resin include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resin, phenoxy resin, acrylic resin, saturated polyester resin, polyamideimide resin, fluororesin, and styrene-isobutylene-styrene block copolymer. The thermoplastic resin may preferably be an acrylic resin from the viewpoint of improving dispersibility with the epoxy resin.

[0038] Examples of the acrylic resin include a carboxyl group-containing (meth)acrylic acid ester copolymer obtained by polymerizing a monomer component including a (meth)acrylic acid alkyl ester having a linear or branched alkyl group and another monomer (copolymerizable monomer). A preferred example of the carboxyl group-containing (meth)acrylic acid ester copolymer is a carboxyl group-containing acrylic acid ester copolymer.

[0039] Examples of the alkyl group include alkyl groups having a carbon number of 1 to 6. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, pentyl, and hexyl.

[0040] Examples of the other monomers include carboxyl group-containing monomers, such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0041] The blending ratio of the thermoplastic component in the first layer 11 is, for example, 0.1 mass% or more, preferably 1 mass% or more, and for example, 10 mass% or less, preferably 3 mass% or less. The blending ratio of the thermoplastic component to the total amount of the thermosetting component and the thermoplastic component in the first layer 11 is, for example, 10 mass% or more, preferably 20 mass% or more, more preferably 25 mass% or more, and for example, 45 mass% or less, preferably 40 mass% or less, more preferably 35 mass% or less.

[0042] Examples of the filler include inorganic fillers (excluding layered silicates) and layered silicates. Examples of the inorganic filler include silicon compounds, aluminum compounds, magnesium compounds, and boron compounds. Examples of the silicon compounds include silicon nitride, silicon carbide, and silicon oxide (silica). Examples of the aluminum compounds include aluminum oxide (alumina), aluminum nitride, and aluminum hydroxide. Examples of the magnesium compounds include magnesium oxide and magnesium hydroxide. Examples of the boron compounds include boron nitride. Examples of the filler include a combination of inorganic fillers (excluding layered silicates) and layered silicates.

[0043] The average particle size of the filler is, for example, 0.1 μm or more, preferably 0.2 μm or more, and, for example, 20 μm or less, preferably 15 μm or less. In addition, two or more fillers having different average particle sizes can be used in combination. Such fillers are described, for example, in JP 2016-162909 A.

[0044] The blending ratio of the filler in the first layer 11 is, for example, 65 mass% or more, preferably 70 mass% or more, more preferably 75 mass% or more, and even more preferably 80 mass% or more, and for example, 95 mass% or less, preferably 90 mass% or less, and more preferably 85 mass% or less. When the blending ratio of the filler in the first layer 11 is within the above-mentioned range, the reliability of sealing the electronic element 3 by the first layer 11 is excellent.

[0045] Examples of the additives include a silane coupling agent and a pigment. Examples of the silane coupling agent include an epoxy group-containing silane coupling agent, specifically 3-glycidoxypropyltrimethoxysilane. The blending ratio of the silane coupling agent in the second layer 12 is, for example, 0.1% by mass or more and 10% by mass or less. Examples of the pigments include carbon black. The blending ratio of the pigment in the first layer 11 is, for example, 0.1% by mass or more and 2% by mass or less.

[0046] 1.1.2 Physical properties of the first layer 11 The viscosity of the first layer 11 at 70° C. is, for example, more than 150 kPa·s, preferably 200 kPa·s or more, and for example, 500 kPa·s or less, preferably 400 kPa·s or less. The viscosity can be measured by the method described in the Examples below.

[0047] The tensile storage modulus E' at 25°C determined by dynamic viscoelastic measurement of the cured first layer 11 at a temperature rise rate of 10°C / min and a frequency of 1 Hz in a tensile mode is more than 2.3 GPa, preferably 2.5 GPa or more, more preferably 5 GPa or more, even more preferably 10 GPa or more, particularly preferably 125 GPa or more, and is 30 GPa or less, preferably 25 GPa or less, more preferably 20 GPa or less. The method for determining the tensile storage modulus E' of the cured first layer 11 will be described in the Examples below.

[0048] 1.1.3 Size of the first layer 11 The first layer 11 has a thickness of, for example, 100 μm or less, preferably 75 μm or less, and for example, 10 μm or more, preferably 25 μm or more.

[0049] 1.2 Second layer12 As shown in FIG. 3, when the encapsulating resin sheet 1 encapsulates the electronic element 3, the second layer 12 is exposed to the outside. That is, the second layer 12 is a cover layer. The second layer 12 has the other side in contact with the first layer 11 and one side located on the opposite side in the thickness direction to the other side. One side of the second layer 12 in the thickness direction is exposed toward one side. As shown in FIG. 1, the second layer 12 is disposed on one side of the first layer 11 in the thickness direction. More specifically, the second layer 12 contacts one side of the first layer 11 in the thickness direction. The second layer 12 includes one side of the encapsulating resin sheet 1 in the thickness direction. One side of the encapsulating resin sheet 1 is flat.

[0050] 1.2.1 Ingredients of the second layer 12 The second layer 12 includes a thermosetting component, a thermoplastic component, and a filler. The thermosetting component includes an epoxy resin, a phenolic resin, and a cure accelerator.

[0051] The epoxy resin may be any of the epoxy resins exemplified for the first layer 11. The epoxy resin of the second layer 12 is preferably different from the epoxy resin of the first layer 11. The epoxy resin may preferably be a bifunctional epoxy resin, more preferably a biphenyl-type epoxy resin. Specific examples of the biphenyl-type epoxy resin include biphenyl aralkyl-type epoxy resins.

[0052] The viscosity of the epoxy resin at 150°C is, for example, 0.02 Pa·s or more, preferably 0.1 Pa·s or more, more preferably 0.2 Pa·s or more, and further preferably 0.25 Pa·s or more, and is, for example, 1 Pa·s or less, preferably 0.5 Pa·s or less, more preferably 0.4 Pa·s or less, and further preferably 0.3 Pa·s or less. If the viscosity of the epoxy resin at 150°C is equal to or greater than the above-mentioned lower limit, the second layer 12 can suppress excessive flow during sealing, and the second layer 12 can suppress contamination of the surrounding members. A catalog value is used as the viscosity of the epoxy resin. The viscosity of the epoxy resin of the second layer 12 is preferably higher than the viscosity of the epoxy resin of the first layer 11.

[0053] The epoxy resin is in a solid or liquid state at 25° C. Preferably, the epoxy resin is in a solid state at 25° C. If the epoxy resin is in a solid state at 25° C., excessive flow of the second layer 12 during heat pressing can be suppressed, and the second layer 12 can be prevented from contaminating surrounding members.

[0054] The phenol resin may be any of the phenol resins exemplified for the first layer 11. The phenol resin of the second layer 12 is preferably different from the phenol resin of the first layer 11. The phenol resin may preferably be a biphenyl-type phenol resin, or more preferably a biphenyl aralkyl phenol resin.

[0055] The viscosity of the phenolic resin at 150°C is, for example, 0.1 Pa·s or more, preferably 0.2 Pa·s or more, more preferably 0.3 Pa·s or more, and for example, 1 Pa·s or less, preferably 0.6 Pa·s or less, more preferably 0.5 Pa·s or less. If the viscosity of the phenolic resin at 150°C is equal to or greater than the above-mentioned lower limit, the second layer 12 can suppress excessive flow during sealing, and the second layer 12 can suppress contamination of surrounding members. The viscosity of the phenolic resin is measured using a cone-plate viscometer. The viscosity of the phenolic resin of the second layer 12 is preferably higher than the viscosity of the phenolic resin of the first layer 11.

[0056] The phenol resin is in a solid or liquid state at 25° C. (room temperature). Preferably, the phenol resin is in a solid state at 25° C. If the phenol resin of the second layer 12 is in a solid state at 25° C., contamination of surrounding members by the second layer 12 can be suppressed.

[0057] The blending ratio of the phenol resin is the same as the blending ratio of the phenol resin exemplified for the first layer 11 .

[0058] Examples of the curing accelerator include the curing accelerators exemplified in the first layer 11. Preferably, the curing accelerator in the second layer 12 is the same as the curing accelerator in the first layer 11. The blending ratio of the curing accelerator is the same as the blending ratio exemplified in the first layer 11.

[0059] The mixing ratio of the thermosetting components (total of the epoxy resin, the phenolic resin, and the curing accelerator) in the second layer 12 is, for example, 20 mass% or more, preferably 30 mass% or more, and for example, 50 mass% or less, preferably 40 mass% or less. The mixing ratio of the thermosetting components in the second layer 12 is higher than the mixing ratio of the thermosetting components in the first layer 11.

[0060] Examples of the thermoplastic component include the thermoplastic components exemplified for the first layer 11. Preferably, the thermoplastic component of the second layer 12 is the same as the thermoplastic component of the first layer 11.

[0061] The blending ratio of the thermoplastic component in the second layer 12 is, for example, 10% by mass or more, preferably 15% by mass or more, more preferably 18% by mass or more, and, for example, 30% by mass or less, preferably 25% by mass or less, more preferably 22.5% by mass or less. The blending ratio of the thermoplastic component to the total amount of the thermosetting component and the thermoplastic component in the second layer 12 is, for example, 25% by mass or more, preferably 30% by mass or more, more preferably 35% by mass or more, and, for example, 55% by mass or less, preferably 50% by mass or less, more preferably 45% by mass or less. If the blending ratio of the thermoplastic component is equal to or more than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, contamination of the surrounding members of the second layer 12 during sealing and heat curing can be suppressed. The blending ratio of the thermoplastic component in the second layer 12 is higher than the blending ratio of the thermoplastic component in the first layer 11.

[0062] The blending ratio of the total amount of epoxy resin and phenol resin to the total amount of thermosetting components and thermoplastic components in the second layer 12 is 48 mass% or more, preferably 50 mass% or more, more preferably 55 mass% or more, and 69 mass% or less, preferably 60 mass% or less, more preferably 58.5 mass% or less. If the blending ratio of the total amount of epoxy resin and phenol resin to the total amount of thermosetting components and thermoplastic components is equal to or more than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, contamination of the surrounding members of the second layer 12 during sealing and heat curing can be suppressed.

[0063] Examples of the filler include the fillers exemplified in the first layer 11. Examples of the filler include preferably an inorganic filler, and more preferably a silicon compound. The inorganic filler of the second layer 12 is the same as the inorganic filler of the first layer 11. Also, preferably, the filler of the second layer 12 does not contain a layered silicate. The average particle diameter of the filler is the same as the average particle diameter of the filler exemplified in the first layer 11.

[0064] The blending ratio of the filler in the second layer 12 is 30% by mass or more, preferably 35% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and 60% by mass or less, preferably 57% by mass or less, more preferably 55% by mass or less, even more preferably 53% by mass or less. If the blending ratio of the filler in the second layer 12 is below the above-mentioned lower limit, the resin (the material of the second layer 12) becomes easily flowable and contaminates the surrounding members. If the blending ratio of the filler in the second layer 12 exceeds the above upper limit, an increase in the tensile storage modulus E' of the second layer 12 after curing cannot be suppressed, and warping of the electronic element package 5 cannot be suppressed. The blending ratio of the filler in the second layer 12 is preferably lower than the blending ratio of the filler in the first layer 11.

[0065] The second layer 12 may contain additives in addition to the thermosetting component, the thermoplastic component, and the filler. The types and blending ratios of the additives are the same as those exemplified for the first layer 11.

[0066] 1.2.2 Physical properties of the second layer 12 The viscosity of the second layer 12 at 70°C is greater than 35 kPa·s, preferably 39 kPa·s or more, more preferably 50 kPa·s or more, even more preferably 70 kPa·s or more, and is 150 kPa·s or less, preferably 130 kPa·s or less, more preferably 110 kPa·s or less.

[0067] If the viscosity of the second layer 12 at 70°C is below the above-mentioned lower limit (35 kPa·s), when the electronic element 3 is encapsulated using the encapsulating resin sheet 1, the second layer 12 is likely to flow, and the surrounding members are contaminated by the second layer 12. Specifically, if the viscosity of the second layer 12 at 70°C is below the above-mentioned lower limit (35 kPa·s), as the fluidity of the second layer 12 increases, the second layer 12 comes into contact with the electronic element 3 and, unlike the first layer 11 which is not exposed to the outside, is exposed to the outside, and therefore the second layer 12 contaminates the surrounding members.

[0068] On the other hand, if the viscosity of the second layer 12 at 70°C exceeds the upper limit (150 kPa·s) described above, the moldability of the second layer 12 at the time of encapsulation decreases. Specifically, one surface of the encapsulating resin sheet 1 in the thickness direction, which is located on one side of the electronic element 3, is not flat and forms a convex portion. Also, if the viscosity of the second layer 12 at 70°C exceeds the upper limit (150 kPa·s) described above, the blending ratio of the thermoplastic component described below may become high. In that case, while the flow of the second layer 12 can be suppressed when encapsulating the electronic element 3 using the encapsulating resin sheet 1, the flowability of the second layer 12 after hardening cannot be suppressed, and the second layer 12 after hardening contaminates the surrounding members.

[0069] The tensile storage modulus E' at 25°C determined by measuring the dynamic viscoelasticity of the cured second layer 12 in a tensile mode at a heating rate of 10°C / min and a frequency of 1 Hz is 0.5 GPa or more, preferably 1 GPa or more, more preferably 1.3 GPa or more, more preferably 1.5 GPa or more, even more preferably 1.7 GPa or more, and is 2.3 GPa or less, preferably 2.0 GPa or less, more preferably 1.8 GPa or less, and even more preferably 1.6 GPa or less.

[0070] If the tensile storage modulus E' of the cured second layer 12 exceeds the above-mentioned upper limit, the cured second layer 12 becomes excessively hard, and as a result, it is not possible to suppress warpage of the electronic element package 5. If the tensile storage modulus E' of the cured second layer 12 falls below the above-mentioned lower limit, the reliability of sealing the electronic element 3 via the first layer 11 decreases.

[0071] The method for determining the tensile storage modulus E' of the second layer 12 after curing will be described in the Examples section below.

[0072] 1.2.3 Size of the second layer 12 The thickness of the second layer 12 is, for example, 100 μm or less, preferably 75 μm or less, and for example, 10 μm or more, preferably 25 μm or more. The ratio of the thickness of the second layer 12 to the thickness of the first layer 11 is, for example, 0.3 or more, preferably 0.5 or more, and for example, 5 or less, preferably 2 or less.

[0073] The thickness of the encapsulating resin sheet 1 shown in FIG. 1 is the sum of the thickness of the first layer 11 and the thickness of the second layer 12, and is, for example, 200 μm or less, preferably 150 μm or less, and for example, 20 μm or more, preferably 50 μm or more.

[0074] 1.3 Manufacturing method of the encapsulating resin sheet 1 The above-mentioned components are mixed to prepare the first resin composition and the second resin composition. Each of the first resin composition and the second resin composition contains a thermosetting component, a thermoplastic component, a filler, and an additive. If necessary, a solvent is mixed into each of the first resin composition and the second resin composition. This prepares the first varnish and the second varnish. As shown in FIG. 2, the first varnish and the second varnish are then applied to the surfaces of the release sheets 13 and 14, respectively, and then dried by heating. This produces the first layer 11 and the second layer 12, respectively. At this time, each of the first layer 11 and the second layer 12 is in a B-stage state. Then, as shown in FIG. 1, the first layer 11 and the second layer 12 are bonded together. This produces an encapsulating resin sheet 1 having the first layer 11 and the second layer 12.

[0075] 2. Manufacturing method of electronic element package 5 Next, a method for manufacturing an electronic element package 5 using the above-mentioned sealing resin sheet 1 will be described with reference to FIG.

[0076] As shown in FIG. 3, first, the above-mentioned sealing resin sheet 1 (see FIG. 1), the mounting substrate 2, and the electronic element 3 are prepared.

[0077] The mounting substrate 2 extends in the planar direction. Examples of materials for the mounting substrate 2 include ceramics, metals, and resins. The mounting substrate 2 has a thickness of 150 μm or less, preferably 125 μm or less, and for example, 90 μm or more, preferably 110 μm or more. If the thickness of the mounting substrate 2 is equal to or less than the above-mentioned upper limit, the electronic device package 5 to be manufactured can be made thin. However, if the thickness of the mounting substrate 2 is equal to or less than the above-mentioned upper limit, the warping of the electronic device package 5 is likely to increase due to a mismatch in the linear expansion coefficients of the mounting substrate 2 and the sealing layer 4. However, in this embodiment, as described later, the tensile storage modulus E' of the sealing resin sheet 1 (sealing layer 4 in the electronic device package 5) after curing is equal to or less than a desired value, and therefore the warping of the electronic device package 5 can be reduced.

[0078] An electronic element 3 is mounted on the mounting board 2. Specifically, the electronic element 3 is disposed on one surface of the mounting board 2 in the thickness direction. A plurality of electronic elements 3 are disposed at intervals from one another in the planar direction. The thickness of each of the plurality of electronic elements 3 is, for example, 250 μm or less, preferably 200 μm or less, and for example, 75 μm or more, preferably 100 μm or more. If the thickness of the electronic element 3 is equal to or less than the above-mentioned upper limit, the electronic element package 5 can be made thin.

[0079] Next, the encapsulating resin sheet 1 is placed on one surface of the electronic element 3 in the thickness direction, with the first layer 11 being in contact with the electronic element 3. Next, the encapsulating resin sheet 1 is heat-pressed against the electronic element 3 and the mounting board 2 using a press (not shown).

[0080] The temperature of the heat press is, for example, 40° C. or more, preferably 60° C. or more, and for example, 100° C. or less, preferably 95° C. or less. The pressure of the heat press is, for example, 0.01 MPa or more, and for example, 10 MPa or less.

[0081] By hot pressing the encapsulating resin sheet 1 , the encapsulating resin sheet 1 flows to cover the peripheral side surface of the electronic element 3 and to come into contact with one surface of the mounting board 2 around the electronic element 3 .

[0082] Thereafter, the encapsulating resin sheet 1 is heated and cured (thermal curing). The heating temperature is, for example, 150° C. or more and, for example, 200° C. or less, preferably 180° C. or less. The heating time is, for example, 10 minutes or more and 200 minutes or less.

[0083] As a result, the sealing resin sheet 1 becomes a C-stage sealing layer 4. The sealing layer 4 seals the electronic element 3. The sealing layer 4 contacts one side of the mounting board 2 and the electronic element 3 in the thickness direction. The thickness of the sealing layer 4 is, for example, 150 μm or less, preferably 100 μm or less, more preferably 75 μm or less, and for example, 50 μm or more. If the thickness of the sealing layer 4 is equal to or less than the above-mentioned upper limit, the thickness of the electronic element package 5 can be made thin. The thickness of the sealing layer 4 is the thickness of the sealing layer 4 arranged on one side of the electronic element 3 in the thickness direction, and is the distance from one side of the electronic element 3 to one side of the sealing layer 4.

[0084] 3. Effects of one embodiment In this sealing resin sheet 1, the viscosity of the second layer 12 at 70°C is greater than 35 kPa s, so that contamination of the surroundings by the second layer 12 during heat pressing can be suppressed. Since the viscosity of the second layer 12 at 70°C is 150 kPa s or less, the resin (material of the second layer 12) flows and can be made flat during pressing, so that marking on the surface of the resin (second layer 12) can be easily performed in the next step.

[0085] Since the tensile storage modulus E' of the second layer 12 after curing is 2.3 GPa or less, warping of the electronic element package 5 including the sealing resin sheet 1 after curing can be reduced.

[0086] Furthermore, in the electronic element package 5, if the thickness of the electronic element 3 is 200 μm or less, the thickness of the mounting substrate 2 is 125 μm or less, and the thickness of the sealing layer 4 is 100 μm or less, the electronic element package 5 can be made thin. EXAMPLES

[0087] The present invention will be described in more detail below with reference to preparation examples, examples, and comparative examples. The present invention is not limited to the preparation examples, examples, and comparative examples. The specific numerical values ​​of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (numeric value defined as "less than or equal to" or "less than") or lower limit (numeric value defined as "more than or equal to" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Form for carrying out the invention".

[0088] The components used in the preparation examples are shown below.

[0089] Epoxy resin A: YSLV-80XY, bisphenol F type epoxy resin, solid at 25°C, viscosity at 150°C 0.008 Pa s, manufactured by Nippon Steel Chemical Co., Ltd. Epoxy resin B: NC-3000-H, biphenyl aralkyl type epoxy resin, solid at 25°C, viscosity at 150°C 0.28 Pa s, manufactured by Nippon Kayaku Co., Ltd. Epoxy resin C: EXA-4850-150, bisphenol A type epoxy resin, liquid at 25°C, viscosity at 25°C: 1.5 Pa s, manufactured by DIC

[0090] Phenolic resin A: MEHC-7851H, biphenyl aralkyl phenolic resin, viscosity 0.4 Pa s at 150°C, manufactured by Meiwa Kasei Co., Ltd. Phenol resin B: MEHC-7851SS, phenol aralkyl resin, liquid at 25°C, viscosity at 150°C 0.07 Pa s, manufactured by Meiwa Kasei Co., Ltd. Phenolic resin C: LVR-8210DL, phenolic novolac resin, liquid at 25°C, viscosity 0.03 Pa s at 150°C, manufactured by Meiwa Kasei Co., Ltd. Phenolic resin D: TPM-100, triphenylmethane type phenolic resin, liquid at 25°C, viscosity at 150°C 0.4 Pa·s, manufactured by Gun-ei Chemical Co., Ltd.

[0091] Acrylic resin: HME-2006M, acrylic resin containing carboxyl groups, manufactured by Negami Chemical Industries, Ltd. Silane coupling agent: KBM-403, 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd. Silica A: FB-8SMFD (spherical fused silica powder (inorganic filler), average particle size 7.0 μm) Silica B: An inorganic filler obtained by surface-treating Admatechs' SC220G-SMJ (average particle size 0.5 μm) with 3-methacryloxypropyltrimethoxysilane (Shin-Etsu Chemical's product name: KBM-503). Layered silicate: Esben NX, manufactured by Hojun Co., Ltd. Curing accelerator: U-CAT 3513N (aliphatic dimethylurea), manufactured by San-Apro Co., Ltd. Pigment: #20 (carbon black), manufactured by Mitsubishi Chemical Corporation

[0092] (Preparation of first layer 11) A first resin composition was prepared according to the formulation shown in Table 1. A first coating film was formed by applying the first resin composition to the surface of a release sheet 13. The release sheet 13 was a PET film, and the surface thereof had been subjected to a silicone release treatment.

[0093] Subsequently, the first coating film was dried by heating at 120° C. for 2 minutes to produce a 50 μm-thick first layer 11. The first layer 11 was in the B stage.

[0094] (Preparation of second layer 12) (Preparation Example A to Preparation Example K) A second resin composition was prepared according to the formulation shown in Table 2. A second coating film was formed by applying the second resin composition to the surface of a release sheet 14. The release sheet 14 was a PET film, and the surface thereof had been subjected to a silicone release treatment.

[0095] Subsequently, the second coating film was dried by heating at 120° C. for 2 minutes to produce a second layer 12 having a thickness of 50 μm. The second layer 12 was in the B stage.

[0096] Example 1 The first layer 11 and the second layer 12 of Preparation Example A were attached to each other at 90° C. In this way, an encapsulating resin sheet 1 having a thickness of 100 μm was produced. The encapsulating resin sheet 1 was in the B stage.

[0097] Example 2 to Comparative Example 6 An encapsulating resin sheet 1 was produced in the same manner as in Example 1. However, the type of the first layer 11 was changed according to Table 2.

[0098] (evaluation) The following items were evaluated, and the results are shown in Table 2.

[0099] (Viscosity of the second layer 12 and the first layer 11 at 70° C.) The second layer 12 was laminated at 90°C to a thickness of about 1 mm to prepare a laminate of the second layer 12. The laminate had a plurality of second layers 12. The laminate was punched out with an 8 mmφ punch to prepare a sample. Thereafter, the viscosity of the sample (second layer 12) was measured using a rheometer (Mars III) with an 8 mmφ plate at a temperature of 70°C, a strain of 0.005%, a frequency of 1 Hz, and a measurement GAP of 0.8 mm.

[0100] The viscosity of the first layer 11 at 70° C. was also measured in the same manner as above.

[0101] (Tensile storage modulus E' of second layer 12 and first layer 11 after curing at 150°C) First, the second layer 12 was cured by heat treatment at 150°C for 1 hour to prepare a test piece. The test piece had a size of 5 mm wide x 40 mm long. Using a dynamic viscoelasticity measuring device (product name "RSA-G2", manufactured by TA Instruments), the test piece was subjected to dynamic viscoelasticity measurement at an initial chuck distance of 20 mm, in a tensile mode, in the range of -10°C to 260°C, at a heating rate of 10°C / min, at a frequency of 1 Hz, and at a dynamic strain of 0.05%. Thus, the tensile storage modulus E' of the second layer 12 at the curing degree at 150°C was obtained.

[0102] For the second layer 12 after curing, the tensile storage modulus E' at 25°C was also determined in the same manner as above.

[0103] (warp) A sealing resin sheet 1 having a thickness of 100 μm was prepared. Specifically, the second layer 12 having a thickness of 50 μm and the first layer 11 having a thickness of 50 μm were laminated at 70° C. using a roll laminator. Then, the outer shape was machined to a size of 45mm x 45mm.

[0104] The above-mentioned sealing resin sheet 1 was attached to the surface of a metal plate made of 42 alloy and having a thickness of 0.15 mm under a load of 0.1 MPa at 90° C. The first layer 11 was pressed onto the surface of the metal plate.

[0105] Thereafter, the sealing resin sheet 1 was heated at 150°C for 1 hour to form a sealing layer 4. After leaving it to stand at 25°C for 1 hour, the average value of the lifting amount of the four corners from the surface of the metal plate was obtained, and the warpage was evaluated according to the following criteria. The lifting amount was measured by placing a ruler on each side of the four corners.

[0106] ○ The amount of floating was 1.0 mm or less. △ The amount of floating was greater than 1.0 mm and less than 1.5 mm. × The amount of floating was 1.5 mm or more.

[0107] [Table 1]

[0108] [Table 2] [Explanation of symbols]

[0109] 1 Sealing resin sheet 2. Mounting Board 3. Electronic elements 4. Sealing layer 5 Electronic device packages

Claims

1. An encapsulating resin sheet for encapsulating an electronic element, The encapsulating resin sheet includes a first layer and a second layer in this order in a thickness direction, When the electronic element is encapsulated in the encapsulating resin sheet, the first layer comes into contact with the electronic element, each of the first layer and the second layer comprises a thermosetting component; the second layer further comprises a thermoplastic component and a filler; The blending ratio of the filler in the second layer is 30% by mass or more and 60% by mass or less, The viscosity of the second layer at 70° C. is greater than 35 kPa·s and less than 150 kPa·s; the second layer after curing has a tensile storage modulus E' at 25°C determined by dynamic viscoelasticity measurement at a temperature rise rate of 10°C / min, a frequency of 1 Hz, and a tensile mode, of 0.5 GPa or more and 2.3 GPa or less.

2. 2. The sealing resin sheet according to claim 1, wherein a blending ratio of the thermoplastic component to a total amount of the thermosetting component and the thermoplastic component in the second layer is 25 mass% or more and 55 mass% or less.

3. The encapsulating resin sheet according to claim 1 , wherein the thermosetting component in the second layer includes an epoxy resin, a phenolic resin, and a curing accelerator.

4. The viscosity of the epoxy resin at 150° C. is 0.1 Pa·s or more, The sealing resin sheet according to claim 3 , wherein the phenol resin has a viscosity of 0.2 Pa·s or more at 150° C.

5. 5. The sealing resin sheet according to claim 3, wherein a blending ratio of a total amount of the epoxy resin and the phenol resin to a total amount of the thermosetting component and the thermoplastic component in the second layer is 48 mass% or more and 69 mass% or less.

6. An electronic element; a mounting substrate on which the electronic element is mounted; a sealing layer that is a cured product of the sealing resin sheet according to claim 1, the sealing layer sealing the electronic element and contacting one side of the mounting board and the electronic element in a thickness direction; The thickness of the electronic element is 200 μm or less, The thickness of the mounting substrate is 125 μm or less, An electronic element package, wherein the sealing layer disposed on one side of the electronic element in a thickness direction has a thickness of 100 μm or less.

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