JP2020155534A - Sealing sheet - Google Patents

Abstract

To provide a sealing sheet capable of achieving both suppression of contamination to the surroundings during sealing and suppression of warpage after sealing.SOLUTION: A sealing sheet 1 is a sealing sheet for sealing an electronic element 51, and includes, in order toward an upper side, a first layer 2 in contact with the electronic element 51 and a second layer 3 exposed to the outside when the electronic component 51 is sealed. The first layer 2 and the second layer 3 have thermosetting properties, respectively. The bottom surface of the first layer 2 is harder than the top surface of the second layer 3 at 90°C, and the elastic modulus of the second layer 3 after thermosetting is greater than the elastic modulus of the first layer 2 after thermosetting.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sealing sheet, specifically, a sealing sheet for sealing an electronic device.

Conventionally, it is known that an electronic element mounted on a substrate is sealed with a sealing sheet to obtain an electronic element package.

As such a sealing sheet, for example, a resin sheet having an outermost layer and an innermost layer and containing a thermosetting resin and an inorganic filler as the outermost layer has been proposed (see, for example, Patent Document 1). .).

JP-A-2018-103584

However, when the resin sheet is heated and pressed to seal the electronic element, the resin sheet flows greatly, gets wet and spreads on the substrate, and the resin sheet protrudes to the outside of the substrate. Then, the resin sheet contaminates the periphery of the substrate (for example, a pressing device).

Further, in the electronic device package after sealing, there is a problem that warpage occurs due to the difference in material between the substrate and the cured resin sheet.

The present invention provides a sealing sheet capable of both suppressing contamination of the surroundings during sealing and suppressing warpage after sealing.

The present invention [1] is a sealing sheet for sealing an electronic element, and when the electronic element is sealed, a first layer that comes into contact with the electronic element and a second layer that is exposed to the outside. The first layer and the second layer have thermosetting properties, respectively, and the other surface of the first layer in the thickness direction is the second layer at 90 ° C. A sealing sheet is included, which is harder than one surface in the thickness direction of the layer and has a thermosetting elasticity of the second layer larger than that of the first layer after thermosetting.

The present invention [2] includes the sealing sheet according to [1], wherein the elastic modulus of the second layer before thermosetting is smaller than the elastic modulus of the first layer before thermosetting.

In the present invention [3], the first layer contains a first organic component containing a first thermosetting resin and a first thermoplastic resin, and the second layer is a second thermosetting resin. The mass ratio of the second thermoplastic resin to the second organic component, which contains the resin and the second organic component containing the second thermoplastic resin, is the mass of the first thermoplastic resin to the first organic component. The sealing sheet according to [1] or [2], which is smaller than the ratio, is included.

According to the sealing sheet of the present invention, the other surface in the thickness direction of the first layer is harder than the one surface in the thickness direction of the second layer at 90 ° C., and the elastic modulus of the second layer after thermosetting is the first. Since it is larger than the elastic modulus of one layer after thermosetting, it is possible to suppress both contamination of the surroundings at the time of sealing and suppression of warpage after sealing.

1A and 1B show a diagram illustrating an embodiment of the sealing sheet of the present invention and its manufacture, FIG. 1A is a sectional view of the sealing sheet, and FIG. 1B is a first layer and a second layer. The figure which prepares each of the layers is shown. 2A-B show a diagram illustrating a method of measuring the dent amount by the iron ball drop test, FIG. 2A is a diagram in which a sealing sheet and an iron ball are prepared, and FIG. 2B is a dent amount and an enlarged view thereof. Is shown. 3A-C are views for explaining a method of sealing an electronic device using the sealing sheet shown in FIG. 1A, and FIG. 3A prepares an electronic element mounting substrate and a sealing sheet, respectively. FIG. 3B shows a diagram in which an electronic device is sealed with a sealing sheet and the sealing sheet is thermoset, and FIG. 3C shows a diagram in which a plurality of electronic device packages are obtained. FIG. 4 shows a plan view when evaluating pollution in the examples. FIG. 5 shows a cross-sectional view when evaluating warpage in an embodiment.

In FIGS. 1A-B and 3-C, the vertical direction of the paper surface is the vertical direction (thickness direction). The upper side of the paper surface is the upper side (one side in the thickness direction), and the lower side of the paper surface is the lower side (the other side in the thickness direction).

As shown in FIGS. 1A and 3A, the sealing sheet 1 according to the embodiment of the present invention has electrons for sealing the electronic element 51 with respect to the electronic member including the substrate 50 and the electronic element 51. A sheet for sealing elements.

Further, the sealing sheet 1 is a component for manufacturing the electronic element package 7 described later, and is not the electronic element package 7 itself, but the sealing sheet 1 contains the electronic element 51 and the electronic element 51. It does not include the substrate 50 to be mounted, and specifically, it is a member that is distributed as a single component and can be industrially used.

The sealing sheet 1 is not a sealing sheet 8 (FIGS. 3B and 3C) after sealing the electronic element 51, that is, a sheet before sealing the electronic element 51.

As shown in FIG. 1A, the sealing sheet 1 has a substantially plate shape (film shape) extending in a direction (plane direction) orthogonal to the thickness direction.

The sealing sheet 1 includes a first layer 2 and a second layer 3 in this order toward the upper side. That is, the sealing sheet 1 includes a first layer 2 and a second layer 3 arranged on the upper surface of the first layer 2. The sealing sheet 1 preferably comprises only the first layer 2 and the second layer 3.

The first layer 2 is a lower layer that forms the lower surface (the surface on the other side in the thickness direction) of the sealing sheet 1. The first layer 2 has a substantially plate shape extending in the plane direction. As will be described later, the first layer 2 is a contact layer that comes into contact with the electronic element 51 when the sealing sheet 1 attempts to seal the electronic element 51 (see FIG. 3A).

The material of the first layer 2 is, for example, a first composition containing a first organic component and a first inorganic filler.

The first organic component contains a first thermosetting resin and a first thermoplastic resin.

The first thermosetting resin is a resin that is once softened by heating when sealing the electronic element 51, further melted and flows, and is cured by further heating.

Further, the first thermosetting resin has a B stage in the first layer 2 before sealing the electronic element 51, not a C stage (that is, a state before complete curing).

Examples of the first thermosetting resin include epoxy resin, phenol resin, melamine resin, vinyl ester resin, cyano ester resin, maleimide resin, and silicone resin. These first thermosetting resins can be used alone or in combination of two or more. As the first thermosetting resin, an epoxy resin and a phenol resin are preferably mentioned from the viewpoint of heat resistance and the like, and a combined use of the epoxy resin and the phenol resin is more preferable.

Examples of the epoxy resin include bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, modified bisphenol A type epoxy resin, modified bisphenol F type epoxy resin, and biphenyl type epoxy resin, for example, phenol novolac type epoxy. Examples thereof include trifunctional or higher functional epoxy resins such as resins, cresol novolac type epoxy resins, trishydroxyphenylmethane type epoxy resins, tetraphenylol ethane type epoxy resins, and dicyclopentadiene type epoxy resins. These epoxy resins can be used alone or in combination of two or more. A bifunctional epoxy resin is preferable, and a bisphenol F type epoxy resin is more preferable.

The epoxy equivalent of the epoxy resin is, for example, 230 g / eq. Hereinafter, preferably 210 g / eq. And, for example, 10 g / eq. As mentioned above, preferably 50 g / eq. That is all.

The softening point of the epoxy resin is, for example, 50 ° C. or higher, preferably 70 ° C. or higher, and for example, 110 ° C. or lower, preferably 90 ° C. or lower.

The proportion of the epoxy resin is, for example, 40% by mass or more, preferably 60% by mass or more, and for example, 90% by mass or less, preferably 70% by mass or less, based on the first thermosetting resin. Is.

Phenolic resin is a resin that cures with epoxy resin. Examples of the phenolic resin include trifunctional or higher functional phenolic resins such as phenol novolac resin, cresol novolac resin, phenol aralkyl resin, phenol biphenylene resin, dicyclopentadiene type phenol resin, and resol resin. These phenolic resins can be used alone or in combination of two or more. Preferably, a phenol novolac resin is used.

The hydroxyl group equivalent of the phenol resin is, for example, 230 g / eq. Hereinafter, preferably 210 g / eq. And, for example, 10 g / eq. As mentioned above, preferably 50 g / eq. That is all.

The softening point of the phenol resin is, for example, 40 ° C. or higher, preferably 50 ° C. or higher, and for example, 90 ° C. or lower, preferably 70 ° C. or lower.

The proportion of the phenol resin is, for example, 10% by mass or more, preferably 30% by mass or more, and for example, 60% by mass or less, preferably 40% by mass or less, based on the first thermosetting resin. Is.

The ratio of the epoxy resin to the phenol resin is such that the total number of hydroxyl groups in the phenol resin is, for example, 0.7 equivalents or more and 1.5 equivalents or less, preferably 0, with respect to 1 equivalent of the epoxy groups in the epoxy resin. It is adjusted so that it is 9 equivalents or more and 1.2 equivalents or less.

The ratio of the first thermosetting resin is, for example, 10% by mass or more, preferably 20% by mass or more, and for example, 50% by mass or less, preferably 40% by mass, based on the first organic component. It is mass% or less. The ratio of the first thermosetting resin to the first composition is, for example, 1% by mass or more, preferably 2% by mass or more, and for example, 10% by mass or less, preferably 5% by mass. % Or less.

The first thermoplastic resin is a resin that is softened by heating, but is not thermosetting.

Examples of the first 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, and the like. Polycarbonate resin, thermoplastic polyimide resin, polyamide resin (6-nylon, 6,6-nylon, etc.), phenoxy resin, acrylic resin, saturated polyester resin (PET, etc.), polyamideimide resin, fluororesin, styrene-isobutylene-styrene block Examples thereof include copolymers. Acrylic resin is preferable.

The acrylic resin includes, for example, an acrylic polymer obtained by polymerizing one or more (meth) acrylic acid alkyl esters having a linear or branched alkyl group as monomer components. Can be mentioned. In addition, "(meth) acrylic" represents "acrylic and / or methacrylic".

Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, amyl, isoamyl, hexyl, heptyl, cyclohexyl, 2-ethylhexyl, octyl, isooctyl, nonyl, isononyl, decyl, Alkyl groups having 1 to 20 carbon atoms such as isodecyl, undecyl, lauryl, tridecyl, tetradecyl, stearyl, octadecyl, and dodecyl can be mentioned. Preferred are alkyl groups having 1 to 6 carbon atoms.

The acrylic polymer may be a copolymer of a (meth) acrylic acid alkyl ester and another monomer (copolymerizable monomer).

Examples of other monomers (copolymerizable monomers) include glycidyl group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, and fumaric acid. , Carboxyl group-containing monomers such as crotonic acid, eg, acid anhydride monomers such as maleic anhydride, itaconic anhydride, eg 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) 4-Hydroxybutyl acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate or (4-4-hydroxylauryl) Hydroxyl group-containing monomers such as hydroxymethylcyclohexyl) -methylacrylate, such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methyl propane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth). ) A sulfonic acid group-containing monomer such as acrylate and (meth) acrylic oxynaphthalene sulfonic acid, for example, a phosphoric acid group-containing monomer such as 2-hydroxyethylacryloyl phosphate, for example, a styrene monomer, for example, acrylonitrile and the like. These monomers can be used alone or in combination of two or more. Among these, a carboxyl group-containing monomer is preferably used.

The glass transition point (Tg) of the first thermoplastic resin is, for example, 30 ° C. or lower, preferably 0 ° C. or lower, more preferably −5 ° C. or lower, and for example, −50 ° C. or higher. When Tg is not more than the above upper limit, the sealing sheet 1 easily penetrates into the gap between the plurality of electronic elements 51 at the time of sealing, and the embedding property is excellent.

The glass transition point is obtained by the maximum value of the loss tangent (tan δ) measured using a dynamic viscoelasticity measuring device (DMA, frequency 1 Hz, heating rate 10 ° C./min).

The weight average molecular weight of the first thermoplastic resin is, for example, 100,000 or more, preferably 300,000 or more, and for example, 1 million or less. The weight average molecular weight is measured by gel permeation chromatography (GPC) based on a standard polystyrene conversion value.

The ratio of the first thermoplastic resin is, for example, 40% by mass or more, preferably 50% by mass or more, more preferably 55% by mass or more, and, for example, 90% by mass or more, based on the first organic component. It is mass% or less, preferably 80 mass% or less, and more preferably 65 mass% or less. The ratio of the first thermoplastic resin to the first composition is, for example, 1% by mass or more, preferably 5% by mass or more, and for example, 30% by mass or less, preferably 20% by mass. It is as follows.

The first organic component may contain other organic components such as a first silane coupling agent in addition to the first thermosetting resin and the first thermoplastic resin. Preferably, the first organic component contains a first silane coupling agent. As a result, the viscosity of the entire resin is lowered, the fluidity of the resin is improved, and the embedding property in the electronic element 51 is improved.

Examples of the first silane coupling agent include a vinyl group-containing silane coupling agent, an epoxy group-containing silane coupling agent, a styryl group-containing silane coupling agent, a (meth) acrylic group-containing silane coupling agent, and an amino group-containing agent. Examples thereof include a silane coupling agent, an isocyanurate group-containing silane coupling agent, and a mercapto group-containing silane coupling agent, and an epoxy group-containing silane coupling agent is preferable.

Examples of the epoxy group-containing silane coupling agent include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glyci. Examples thereof include sidoxylpropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane. Preferably, from the viewpoint of reactivity, 3-glycidoxypropyltriethoxysilane can be mentioned.

The ratio of the first silane coupling agent to the first organic component is, for example, 1% by mass or more, preferably 5% by mass or more, and for example, 20% by mass or less, preferably 15. It is mass% or less. The ratio of the first silane coupling agent to the first composition is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, and for example, 5% by mass or less, preferably 5% by mass or less. Is 3% by mass or less.

The ratio of the first organic component to the first composition is, for example, 5% by mass or more, preferably 10% by mass or more, and for example, 50% by mass or less, preferably 35% by mass or less. , More preferably, it is 20% by mass or less.

Examples of the first inorganic filler include quartz glass, talc, silica (molten silica, crystalline silica, etc.), alumina, aluminum nitride, silicon nitride, boron nitride and the like. These inorganic fillers can be used alone or in combination of two or more. As the inorganic filler, silica and alumina are preferable, and silica is more preferable.

The size of the first inorganic filler is not particularly limited, and specifically, the average particle size is, for example, 0.1 μm or more, preferably 0.2 μm or more, and for example, 20 μm or less, preferably. Is 15 μm or less. Further, two or more kinds of inorganic fillers having different average particle diameters can be used in combination. Such an inorganic filler is described in, for example, Japanese Patent Application Laid-Open No. 2016-162909.

The ratio of the first inorganic filler to the first composition is, for example, 50% by mass or more, preferably 65% by mass or more, more preferably 80% by mass or more, and for example, 95% by mass. % Or less, preferably 90% by mass or less. When the ratio of the first inorganic filler is in the above range, the heat resistance and reliability can be improved in the electronic device package 7 (described later).

In addition, the first composition may contain a curing accelerator and a pigment.

The curing accelerator is a catalyst (thermosetting catalyst) that accelerates the curing of a thermosetting resin by heating. Examples of the curing accelerator include imidazole compounds such as 2-phenyl-4,5-dihydroxydimethylimidazole (2PHZ-PW) and 2-phenyl-4-methyl-5-hydroxymethylimidazole (2P4MHZ), for example, organic phosphorus. Examples include system compounds. Preferably, an imidazole compound is mentioned. In addition, clathrate compounds in which the above-mentioned imidazole compound is used as a guest and hydroxyisophthalic acid (HIPA) or the like is hosted can also be mentioned. The clathrate compound is described in, for example, Japanese Patent Application Laid-Open No. 2012-232994. These curing accelerators can be used alone or in combination of two or more.

The ratio of the curing accelerator is, for example, 0.1 part by mass or more and, for example, 5 parts by mass or less with respect to 100 parts by mass of the first thermosetting resin.

Examples of the pigment include a black pigment such as carbon black. The average particle size of the pigment is, for example, 0.001 μm or more and 1 μm or less. These pigments can be used alone or in combination of two or more.

The proportion of the pigment is, for example, 0.1% by mass or more and, for example, 5% by mass or less with respect to the first composition.

Further, the first composition can contain additives other than the above-mentioned components in an appropriate ratio.

The thickness T1 of the first layer 2 is, for example, 10 μm or more, preferably 50 μm or more, and for example, 200 μm or less, preferably 100 μm or less.

The second layer 3 is an upper layer that forms the upper surface (the surface on one side in the thickness direction) of the sealing sheet 1. The second layer 3 has a substantially plate shape extending in the plane direction. The second layer 3 is arranged on the entire upper surface of the first layer 2. As will be described later, the second layer 3 is an exposed layer that is exposed to the outside (upper side) when the sealing sheet 1 seals the electronic element 51. The second layer 3 is preferably a non-contact layer that does not come into contact with the electronic element 51.

The material of the second layer 3 is a second composition containing a second organic component and a second inorganic filler.

The second organic component contains a second thermosetting resin and a second thermoplastic resin.

Examples of the second thermosetting resin include the same thermosetting resins as those exemplified in the first thermosetting resin. The second thermosetting resin preferably includes an epoxy resin and a phenol resin, and specific examples thereof include a combined use of an epoxy resin and a phenol resin.

The ratio of the epoxy resin to the second thermosetting resin is, for example, 40% by mass or more, preferably 60% by mass or more, and for example, 90% by mass or less, preferably 70% by mass or less. Is.

The proportion of the phenol resin is, for example, 10% by mass or more, preferably 30% by mass or more, and for example, 60% by mass or less, preferably 40% by mass or less, based on the second thermosetting resin. Is.

The ratio of the epoxy resin to the phenol resin is such that the total number of hydroxyl groups in the phenol resin is, for example, 0.7 equivalents or more and 1.5 equivalents or less, preferably 0, with respect to 1 equivalent of the epoxy groups in the epoxy resin. It is adjusted so that it is 9 equivalents or more and 1.2 equivalents or less.

The ratio of the second thermosetting resin is, for example, 60% by mass or more, preferably 70% by mass or more, and, for example, 95% by mass or less, preferably 90% by mass, based on the second organic component. It is mass% or less. The ratio of the second thermosetting resin to the second composition is, for example, 5% by mass or more, preferably 10% by mass or more, and for example, 25% by mass or less, preferably 15% by mass. % Or less.

Examples of the second thermoplastic resin include the same thermoplastic resins as those exemplified in the first thermoplastic resin. Acrylic resin is preferable.

The ratio of the second thermoplastic resin to the second organic component is, for example, 1% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, and for example, 40. It is mass% or less, preferably 30 mass% or less, and more preferably 20 mass% or less. The ratio of the second thermoplastic resin to the second composition is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, and for example, 10% by mass or less, preferably 10% by mass or less. 5, 5% by mass or less.

Preferably, the mass ratio A2 of the second thermoplastic resin to the second organic component is smaller than the mass ratio A1 of the first thermoplastic resin to the first organic component. Specifically, the difference in these mass ratios (A1-A2) is, for example, 25% by mass or more, preferably 40% by mass or more, and for example, 60% by mass or less, preferably 50% by mass. It is as follows. When the above difference is within the above range, the lower surface of the first layer 2 is more reliably harder than the upper surface of the second layer 3, and the elastic modulus of the second layer 3 after thermosetting is higher than that of the first layer 2. It can be made larger than the elastic modulus after thermosetting.

In addition to the second thermosetting resin and the second thermoplastic resin, the second organic component may contain other organic components such as a second silane coupling agent. Preferably, the second organic component contains a second silane coupling agent. As a result, the viscosity of the entire resin is lowered, the fluidity of the resin is improved, and the embedding property in the electronic element 51 is improved.

Examples of the second silane coupling agent include the same silane coupling agents as those exemplified in the first silane coupling agent. Preferably, an epoxy group-containing silane coupling agent is used.

The ratio of the second silane coupling agent to the second organic component is, for example, 1% by mass or more, preferably 5% by mass or more, and for example, 20% by mass or less, preferably 15. It is mass% or less. The ratio of the second silane coupling agent to the second composition is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, and for example, 5% by mass or less, preferably 5% by mass or less. Is 3% by mass or less.

The ratio of the second organic component to the second composition is, for example, 5% by mass or more, preferably 10% by mass or more, and for example, 50% by mass or less, preferably 35% by mass or less. , More preferably, it is 20% by mass or less.

Examples of the second inorganic filler include the same inorganic fillers as those exemplified in the first inorganic filler. Preferred is silica.

The ratio of the second inorganic filler to the second composition is, for example, 50% by mass or more, preferably 65% by mass or more, more preferably 80% by mass or more, and for example, 95% by mass. % Or less, preferably 90% by mass or less. When the ratio of the second inorganic filler is within the above range, the heat resistance and reliability can be improved in the electronic device package 7 (described later).

The ratio [C2 / C1] of the ratio C2 (mass%) of the second inorganic filler to the second composition and the ratio C1 (mass%) of the first inorganic filler to the first composition is For example, it is 0.5 or more, preferably 0.8 or more, and for example, 2.0 or less, preferably 1.3 or less. When the above ratio is within the above range, cracks at the interface between the first layer 2 and the second layer 3 can be suppressed in the electronic device package 7 (described later).

The second composition may contain the curing accelerator, the pigment and the like exemplified in the first composition in an appropriate ratio.

The thickness T2 of the second layer 3 is, for example, 50 μm or more, preferably 100 μm or more, more preferably 150 μm or more, and for example, 1000 μm or less, preferably 500 μm or less, more preferably 300 μm or less. ..

The ratio (T2 / T1) of the thickness T2 of the second layer 3 to the thickness T1 of the first layer 2 is, for example, 1 or more, preferably 1.5 or more, more preferably 2 or more, and, for example, It is 10 or less, preferably 5 or less, and more preferably 4 or less. When the above ratio is within the above range, the protrusion can be suppressed more reliably.

In the sealing sheet 1, the lower surface of the first layer 2 (the other surface in the thickness direction) is harder than the upper surface of the second layer 3 (one surface in the thickness direction) at 90 ° C. That is, the upper surface of the second layer 3 is softer than the lower surface of the first layer 2 at 90 ° C. In other words, the lower surface of the first layer 2 is less likely to be dented than the upper surface of the second layer 3 at 90 ° C.

Specifically, as shown in the iron ball drop test of FIG. 2A, the sealing sheet 1 is arranged on the heating table 10 so that the first layer 2 is on the upper side, and the sealing sheet 1 is placed at 90 ° C. The iron ball 11 is subsequently dropped onto the surface (lower surface) of the first layer 2. At that time, as shown in FIG. 2B, the amount of dent (depth) formed on the surface of the first layer 2 is defined as D1. Similarly, the sealing sheet 1 is arranged on the heating table 10 so that the second layer 3 is on the upper side, the sealing sheet 1 is heated to 90 ° C., and then the second layer 3 The iron ball 11 is dropped on the surface (upper surface). At that time, the amount of dent (depth) formed on the surface of the second layer 3 is defined as D2. In this case, the dent amount D1 of the first layer 2 is smaller than the dent amount D2 of the second layer 3. That is, D1 <D2 is satisfied.

Specifically, the dent amount D1 in the iron ball drop test is, for example, less than 80 μm, preferably 65 μm or less, and for example, 10 μm or more, preferably 30 μm or more.

The dent amount D2 in the iron ball drop test is, for example, 80 μm or more, preferably 100 μm or more, and for example, 200 μm or less, preferably 160 μm or less.

The size of the iron ball is 18 mm in diameter, its weight is 21.7 g, and its drop height is 10 cm. Details will be described in Examples.

If the first layer 2 is harder than the second layer 3 at 90 ° C., the sealing sheet 1 can be heated to suppress the protrusion of the sealing sheet 1 when the electronic element 1 is sealed. it can. Therefore, contamination around the electronic device package 7 can be suppressed.

In the sealing sheet 1, the elastic modulus of the second layer 3 (that is, the elastic modulus of the second layer 3 before heat curing) is preferably the elastic modulus of the first layer 2 (that is, the first before heat curing). It is smaller than the elastic modulus of layer 2).

The elastic modulus of the second layer 3 is, for example, less than 3.0 × 10 ^-3 GPa, preferably 2.5 × 10 ^-3 GPa or less, and for example, 1.0 × 10 ^-5 GPa or more. Preferably, it is 1.0 × 10 ^-4 GPa or more.

The elastic modulus of the first layer 2 is, for example, 3.0 × 10 ^-3 GPa or more, preferably 4.0 × 10 ^-3 GPa or more, and for example, 1.0 × 10 ^-1 GPa or less. Preferably, it is 1.0 × ^10-2 GPa or less.

The ratio of the elastic modulus of the second layer 3 to the elastic modulus of the first layer 2 (second layer / first layer) is, for example, less than 1.0, preferably 0.8 or less, and for example. , 0.1 or more, preferably 0.3 or more.

The elastic modulus is the indentation elastic modulus, which is measured, for example, by performing an indentation test on the surface of each layer (first layer or second layer) at room temperature (25 ° C.), and specifically, super Use a microhardness meter. Details will be described in Examples.

In the sealing sheet 1, if the elastic modulus of the second layer 3 is smaller than the elastic modulus of the first layer 2, the protrusion of the sealing sheet 1 can be further suppressed.

To manufacture the sealing sheet 1, each of the first layer 2 and the second layer 3 is prepared as shown in FIG. 1B.

For example, the first composition is dissolved and / or dispersed in a solvent (eg, methyl ethyl ketone, toluene, ethyl acetate, etc.) to prepare a first varnish, which is applied to the first release sheet 4 shown by a virtual line. ,dry. As a result, the first layer 2 is prepared in a state of being supported by the first release sheet 4.

The second composition is dissolved and / or dispersed in a solvent to prepare a second varnish, which is applied to the second release sheet 5 shown by a virtual line and dried. As a result, the second layer 3 is prepared while being supported by the second release sheet 5.

It is also possible to prepare the first layer 2 and / or the second layer 3 by kneading extrusion without preparing the varnish.

The first thermosetting resin in the first layer 2 and the second thermosetting resin in the second layer 3 are, for example, B stages.

After that, the first layer 2 and the second layer 3 are bonded together.

Next, a method of sealing the electronic element 51 to manufacture the electronic element package 7 using the sealing sheet 1 will be described with reference to FIGS. 3A-C. The electronic device 51, the electronic device package 7, and a method for manufacturing the same are also described in JP-A-2016-162909.

As shown in FIG. 3A, first, the electronic element 51 is prepared.

The electronic element 51 has a substantially flat plate shape extending in the plane direction. The electronic element 51 is not particularly limited, and examples thereof include various electronic elements, such as hollow electronic elements and semiconductor elements. A plurality of electronic elements 51 are mounted so as to face the upper surface of the substrate 50. The plurality of electronic elements 51 are, for example, flip-chip mounted on the substrate 50. In this case, electrodes (not shown) provided on the lower surfaces of the plurality of electronic elements 51 are electrically connected to terminals (not shown) provided on the upper surface of the substrate 50. Further, the electronic element 51 may be die-bonded to the electronic element 51 via an adhesive layer (die bonding film or the like) (not shown).

To prepare the electronic element 51, an electronic element mounting substrate 55 including the electronic element 51 and the substrate 50 on which the electronic element 51 is mounted is prepared.

The board 50 is, for example, a printed wiring board. The substrate 50 has a substantially flat plate shape extending in the plane direction. The substrate 50 has a size surrounding a plurality of electronic elements 51 in a plan view. The substrate 50 has a terminal (not shown) that is electrically connected to the electronic element 51 on its upper surface. The substrate 50 is made of, for example, a ceramic plate, a glass epoxy plate, or the like.

Next, the sealing sheet 1 is prepared.

The size of the sealing sheet 1 is adjusted to a size that allows a plurality of electronic elements 51 to be sealed together, that is, a size that includes all of the plurality of electronic elements 51 when projected in the thickness direction. Has

As shown in FIG. 3B, the electronic element 51 is then sealed with the sealing sheet 1.

For example, the electronic element 51 is sealed with the sealing sheet 1 by using a flat plate press 97 including the lower plate 98 and the upper plate 99 shown by the virtual line in FIG. 3B.

The electronic element mounting substrate 55 is arranged on the lower plate 98. Specifically, the lower surface of the substrate 50 is placed on the upper surface of the lower plate 98.

Subsequently, the sealing sheet 1 is arranged on the electronic element mounting substrate 55. Specifically, the first layer 2 is brought into contact with the upper surfaces of the plurality of electronic elements 51. On the other hand, the second layer 3 faces the upper side. At this time, if the first release sheet 4 supports the first layer 2, the first release sheet 4 is peeled from the first layer 2.

Next, the upper plate 99 is pushed down toward the sealing sheet 1. At the same time, the sealing sheet 1 is heated by heat sources (not shown) provided on the lower plate 98 and the upper plate 99.

The heating temperature is, for example, 40 ° C. or higher, preferably 60 ° C. or higher, and for example, 100 ° C. or lower, preferably 95 ° C. or lower. The pressure is, for example, 0.05 MPa or more, preferably 0.1 MPa or more, and for example, 10 MPa or less, preferably 5 MPa or less. The press time is, for example, 0.3 minutes or more, preferably 0.5 minutes or more, and for example, 10 minutes or less, preferably 5 minutes or less.

In the hot press, in addition to the flat plate press 97 (virtual line in FIG. 3B), a roll press or the like is also used.

When the sealing sheet 1 is hot-pressed, the sealing sheet 1 is softened and a plurality of electronic elements 51 are embedded. In other words, a plurality of electronic elements 51 are embedded in the sealing sheet 1.

Specifically, the first layer 2 covers the upper surface and the side surface of the electronic element 51 and the upper surface of the substrate 50 that does not overlap with the electronic element 51 when projected in the thickness direction. That is, the first layer 2 is plastically deformed according to the outer shape of the electronic element 51.

On the other hand, the lower surface of the second layer 3 is deformed in response to the deformation of the first layer 2, while the upper surface of the second layer 3 is pressed by the upper plate 99, so that the flat shape is maintained.

At this time, since the first layer 2 is hard, it does not spread excessively on the substrate 50 and does not easily flow to the outside of the substrate 50, that is, to the lower plate 98. Therefore, the first layer 2 does not easily reach the side surface or the lower surface of the lower plate 98 or the substrate 50, and contamination to the surroundings is suppressed.

Then, the sealing sheet 1 is cured by heating. Specifically, the first thermosetting resin contained in the first layer 2 and the second thermosetting resin contained in the second layer 3 are thermally cured (completely cured, C-staged).

After sealing and curing, the sheet that seals the electronic element 51 is no longer the sealing sheet 1 but the sealing sheet 8. The sealing sheet 8 does not have a flat plate shape, but has a recess corresponding to the electronic element 51 and opening downward.

In the sealing sheet 8, the first thermosetting resin and the second thermosetting resin are C-tages.

If the second release sheet 5 supports the second layer 3 before the sealing sheet 1 is heat-cured, the second release sheet 5 is peeled from the second layer 3. Alternatively, the second release sheet 5 can be peeled from the second layer 3 before the electronic element 51 is sealed by the sealing sheet 1.

The heating temperature (cure temperature) is, for example, 100 ° C. or higher, preferably 120 ° C. or higher, and for example, 200 ° C. or lower, preferably 180 ° C. or lower. The heating time is, for example, 10 minutes or more, preferably 30 minutes or more, and for example, 180 minutes or less, preferably 120 minutes or less.

In order to thermoset the sealing sheet 1, the sealing sheet 1, the electronic element 51 and the substrate 50 are taken out from the flat plate press 97 and put into a heating furnace or the like, for example. It is also possible to heat-cure the sealing sheet 1 by using the heat source provided in the flat plate press 97 without removing the sealing sheet 1, the electronic element 51 and the substrate 50 from the flat plate press 97.

If necessary, the upper surface of the second layer 3 located on the plurality of electronic elements 51 is then marked (marked) by laser irradiation or the like. The mark includes information (product information, lot number, etc.) regarding the electronic device package 7 described below.

In the sealing sheet 8 (sealing sheet 1 after heat curing), the elastic modulus of the second layer 3 (that is, the elastic modulus of the second layer 3 after heat curing) is the elastic modulus of the first layer 2 (that is, that is. , The elastic modulus of the first layer 2 after heat curing).

The elastic modulus of the second layer 3 after thermosetting is, for example, 1.0 GPa or more, preferably 2.0 GPa or more, and for example, 100 GPa or less, preferably 10 GPa or less.

The elastic modulus of the first layer 2 after thermosetting is, for example, less than 1.0 GPa, preferably 0.5 GPa or less, and for example, 0.01 GPa or more, preferably 0.1 GPa or more.

The ratio of the elastic modulus of the second layer 3 to the elastic modulus of the first layer 2 (second layer / first layer) is, for example, 1.0 or more, preferably 5.0 or more, and for example, 20. Hereinafter, it is preferably 15 or less.

In the sealing sheet 8, when the elastic modulus of the second layer 3 is larger than the elastic modulus of the first layer 2, the warp of the electronic element package 7 can be suppressed.

Further, since the second layer 3 has a relatively high elastic modulus, marking of the electronic device package 7 is easy. Further, the grind for lowering the package height can be facilitated, and the wear of the grindstone can be reduced.

As shown in FIG. 3C, the sealing sheet 8 between the plurality of electronic elements 51 is then cut by dicing, for example, to separate the electronic element 51 and the substrate 50 into individual pieces. As a result, the electronic element package 7 including one sealing sheet 8, one electronic element 51, and one substrate 50 is manufactured.

After that, the electronic element package 7 is mounted on another substrate.

Then, in the sealing sheet 1 (the sheet before forming the sealing sheet 8) shown in FIG. 1A, the lower surface of the first layer 2 is harder than the upper surface of the second layer 3 at 90 ° C. Therefore, when the sealing sheet 1 is heated to seal the electronic element 1, the relatively hard first layer 2 comes into contact with the electronic element 51 and the substrate 50, so that it becomes difficult to wet and spread. Therefore, the protrusion of the sealing sheet 1 can be suppressed. Therefore, contamination around the electronic device package 7 can be suppressed. That is, it is excellent in low pollution. Further, since the first layer 2 does not easily protrude in the state of sealing (before curing and dicing) shown in FIG. 3B, it is possible to suppress deformation of the end portion of the second layer 3, and the yield of the electronic element package 7 can be suppressed. Can be improved.

Further, in the sealing sheet 1, the elastic modulus of the second layer 3 after thermosetting is larger than the elastic modulus of the first layer 2 after thermosetting. Therefore, the warp of the electronic device package 7 can be suppressed. That is, the electronic device package 7 includes a substrate 50 and a second layer 3, and sandwiches the first layer 2 by these. Therefore, even when the electronic device package 7 is left at a high temperature, the electronic device package 7 has a sandwich structure composed of a substrate 50 (for example, a ceramic substrate) having a relatively high elastic modulus and a second layer 3. Therefore, it is possible to suppress the occurrence of warpage of the electronic element package 7. Further, the laser marking property for the second layer 3 is good. In addition, since there is little dimensional change, reliability by thermal cycle test or the like is good.

Further, in the sealing sheet 1, if the elastic modulus of the second layer 3 before thermosetting is smaller than the elastic modulus of the first layer 2 before thermosetting, the protrusion of the sealing sheet 1 is further suppressed. can do. Further, since the second layer 3 (upper layer) is plastically deformable, the influence of the unevenness on the upper surface of the electronic element 51 can be reduced, and as a result, the upper surface of the electronic element package 7 can be made flat.

Further, if the ratio of the second thermoplastic resin to the second organic component is smaller than the ratio of the first thermoplastic resin to the first organic component, the physical properties of the sealing sheet 1 can be easily adjusted. be able to. Further, since the proportion of the first thermoplastic resin is high, the sheet has good flexibility, good handleability at the time of sealing, and the occurrence of cracks can be suppressed.

Examples and comparative examples are shown below, and the present invention will be described in more detail. The present invention is not limited to Examples and Comparative Examples. In addition, specific numerical values such as the compounding ratio (content ratio), physical property values, and parameters used in the following description are the compounding ratios corresponding to those described in the above-mentioned "Form for carrying out the invention". Substitute for the upper limit (numerical value defined as "less than or equal to" or "less than") or lower limit (numerical value defined as "greater than or equal to" or "exceeded") such as content ratio), physical property value, and parameters. it can.

Each component used in Examples and Comparative Examples is shown below.
YSLV-80XY: Epoxy resin (bisphenol F type epoxy resin), Epokin equivalent: 200 g / eq. , Softening point: 80 ° C., LVR8210DL manufactured by Nippon Steel Chemical Co., Ltd .: Phenolic resin (novolac type phenol resin), hydroxyl group equivalent: 104 g / eq. , Softening point: 60 ° C, HME-2006M manufactured by Gunei Chemical Co., Ltd .: Acrylic resin (methyl ethyl ketone solution of 20% by mass of acrylic acid ester polymer containing carboxyl group, weight average molecular weight: about 600,000, Tg: -30 ° C, root SG-70L manufactured by Kogyo Co., Ltd .: Acrylic resin (methyl ethyl ketone solution of 12.5% by mass of acrylic acid ester polymer containing carboxyl group, weight average molecular weight: about 800,000, Tg: -10 ° C, KBM-403 manufactured by Nagase ChemteX Co., Ltd. : Epoxysilane coupling agent, 3-glycidoxypropyltrimethoxysilane, Shin-Etsu Silicone FB-8SM: Silica, average particle size: 6 μm, Denka SC220G-SMJ: silica, average particle size: 0.5 μm, Admatex # 20: Carbon black, average molecular weight: 50 nm, Mitsubishi Chemical 2PHZ-PW: Curing accelerator, imidazole compound (2-phenyl-4,5-dihydroxydimethylimidazole), Shikoku Kasei Co., Ltd. Example 1
Each component was dissolved and dispersed in methyl ethyl ketone according to the formulation shown in Table 1 (the numerical value in Table 1 indicates the amount of solid content) to obtain a first varnish and a second varnish. The solid content concentration of the first varnish was 84% by mass, and the solid content concentration of the second varnish was 70% by mass.

Each of the first varnish and the second varnish was applied to the surfaces of the first release sheet 4 and the second release sheet 5, and then dried at 110 ° C. for 5 minutes. As a result, each of the first layer 2 having a thickness of 65 μm and the second layer 3 having a thickness of 195 μm was prepared.

Then, the first layer 2 and the second layer 3 were bonded together. As a result, a sealing sheet 1 provided with the first layer 2 (lower layer) and the second layer 3 (upper layer) was produced.

Examples 2-3 and Comparative Examples 1-4
A sealing sheet 1 was prepared in the same manner as in Example 1 according to the formulation shown in Table 1.

(Evaluation)
The following items were evaluated. The results are shown in Table 2.

<Measurement of dent amount by iron ball drop test>
Polyethylene terephthalate (thickness 38 μm) was placed on the upper surface and the lower surface of the sealing sheet (50 mm × 50 mm) of each Example and each Comparative Example, respectively. Next, the iron ball 11 (diameter 18 mm, weight 21.7 g) was placed on a hot plate 10 at 90 ° C. so that the first layer was on the lower side and the second layer was on the upper side, and the height was 10 cm. Was dropped onto the upper surface of the sealing sheet. After the fall, the iron ball 11 was removed by leaving it for 5 minutes (see FIGS. 2A-B).

The amount of dent D2 on the upper surface of the sealing sheet (the surface on the second layer side) was measured using a 3CCD color confocal microscope (Lasertec, "MC-1000A") in confocal mode and at a magnification of 5 times. It was measured.

The amount of dent D1 on the surface of the first layer was measured in the same manner as above, except that the first layer was arranged on the upper side and the second layer was on the lower side.

These results are shown in Table 2.

<Measurement of elastic modulus>
The indentation elastic modulus of the first layer and the second layer for sealing of each Example and each Comparative Example was measured 5 times under the following conditions using a micro surface hardness tester, and the average value was obtained.

Further, the sealing sheets of each Example and each Comparative Example were heated under the condition of 150 ° C. for 1 hour to be completely cured. The indentation elastic modulus of the first layer and the second layer of the cured sheet (sealing sheet) was determined in the same manner as described above. These results are shown in Table 2.

Equipment: "DUH-211", manufactured by Shimadzu Corporation Test mode: Load-unloading test
Test force: 0.5 mN (before curing), 9.8 mN (after curing)
Setting depth: 1.0000 μm
Load speed: 1.0 mN / sec
Data processing: Dynamic hardness Sample size: 1 cm x 1.5 cm x thickness 260 μm
<Evaluation of pollution control (protrusion control)>
A glass plate 20 having a thickness of 100 mm × 100 mm × thickness 1.1 mm was prepared. A sealing sheet 1 (80 mm × 80 mm × thickness 260 μm) of each Example and each Comparative Example was arranged in the center of the glass plate 20 so that the first layer was in contact with the glass plate 20, and the pressure was 0. These were bonded together under the conditions of 1 MPa, 90 ° C. and 1 minute.

Next, in the sealing sheet after bonding, the lengths L ₁ and L ₂ of the straight line connecting the midpoints of the two opposing sides were measured (see FIG. 4). With the larger value as A, the protrusion ratio X was calculated by the following formula.

X [%] = (A [mm] / 80 [mm]) x 100
When X is 100% or more and 105% or less, it is evaluated as ◯, when X exceeds 105% and is 110% or less, it is evaluated as Δ, and when X exceeds 110%, it is evaluated as ×. I evaluated it. The results are shown in Table 2.

<Evaluation of warpage suppression>
A ceramic plate 30 having a thickness of 100 mm × 100 mm × thickness 200 μm was prepared. A sealing sheet (80 mm × 80 mm × thickness 260 μm) of each Example and each Comparative Example was placed in the center of the ceramic plate 30 so that the first layer was in contact with each other, and the pressure was 0.1 MPa with a vacuum plate press. , 90 ° C., 1 minute, and the like, to obtain a laminated body 31.

Next, the laminate 31 was placed in a dryer at 150 ° C. for 1 hour to completely cure the sealing sheet to obtain a sealing sheet 8. Then, the laminated body 31 was returned to room temperature and placed on the horizontal table 32. The average value of the heights of the four corners of the ceramic plate 30 and the horizontal base 32 was measured as the amount of warpage (see FIG. 5).

A case where the amount of warpage was 5 mm or less was evaluated as ◯, and a case where the amount of warpage exceeded 5 mm was evaluated as x. The results are shown in Table 2.

1 Sealing sheet 2 1st layer 3 2nd layer 8 Sealing sheet 50 Substrate 51 Electronic element

Claims (3)

A sealing sheet for sealing electronic devices.
When sealing the electronic element, a first layer in contact with the electronic element and a second layer exposed to the outside are provided in order toward one side in the thickness direction.
The first layer and the second layer are each thermosetting and have a thermosetting property.
The other surface in the thickness direction of the first layer is harder than the one surface in the thickness direction of the second layer at 90 ° C.
A sealing sheet, characterized in that the elastic modulus of the second layer after thermosetting is larger than the elastic modulus of the first layer after thermosetting. The sealing sheet according to claim 1, wherein the elastic modulus of the second layer before thermosetting is smaller than the elastic modulus of the first layer before thermosetting. The first layer contains a first organic component containing a first thermosetting resin and a first thermoplastic resin.
The second layer contains a second organic component containing a second thermosetting resin and a second thermoplastic resin.
The seal according to claim 1 or 2, wherein the mass ratio of the second thermoplastic resin to the second organic component is smaller than the mass ratio of the first thermoplastic resin to the first organic component. Stop sheet.

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