JP7343989B2 - Sealing sheet - Google Patents

Description

The present invention relates to a sealing sheet, and more particularly to a sealing sheet for sealing an electronic device.

2. Description of the Related Art Conventionally, it has been known to seal electronic elements mounted on a substrate with a sealing sheet to obtain an electronic element package.

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

Japanese Patent Application Publication No. 2018-103584

However, when heating and pressing the resin sheet to seal an electronic element, the resin sheet flows considerably and spreads over the substrate, causing a problem that the resin sheet protrudes outside the substrate. In this case, the resin sheet contaminates the area around the substrate (eg, press equipment, etc.).

Further, in the electronic device package after being sealed, warping may occur due to the difference in materials between the substrate and the cured resin sheet.

The present invention provides a sealing sheet that can both suppress contamination of the surroundings during sealing and suppress warpage after sealing.

The present invention [1] is a sealing sheet for sealing an electronic device, which includes a first layer that contacts the electronic device and a second layer that is exposed to the outside when the electronic device is sealed. are provided in order toward one side in the thickness direction, the first layer and the second layer each have thermosetting properties, and the other surface of the first layer in the thickness direction is The sealing sheet includes a sealing sheet that is harder than one surface in the thickness direction of the layer, and the elastic modulus of the second layer after thermosetting is larger than the elastic modulus 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 includes a first organic component containing a first thermosetting resin and a first thermoplastic resin, and the second layer includes a second thermosetting resin. a second organic component containing a resin and a second thermoplastic resin, the mass ratio of the second thermoplastic resin to the second organic component is the mass ratio of the first thermoplastic resin to the first organic component; The sealing sheet according to [1] or [2] is included, which is smaller than the proportion.

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 Since the elastic modulus is higher than the elastic modulus of one layer after thermosetting, it is possible to suppress contamination of the surroundings during sealing and suppress warpage after sealing.

FIG. 1A and FIG. 1B show diagrams explaining one embodiment of the sealing sheet of the present invention and its manufacture, in which FIG. 1A is a cross-sectional view of the sealing sheet, and FIG. The diagram shows the preparation of each of the layers. 2A-B show diagrams explaining the method for measuring the amount of dent by iron ball drop test, FIG. 2A is a diagram showing preparing a sealing sheet and iron ball, and FIG. 2B is a diagram showing the amount of dent and its enlarged view. shows. 3A to 3C are diagrams illustrating a method for encapsulating an electronic device using the encapsulation sheet shown in FIG. 1A, and FIG. Figures 3B and 3B show how electronic devices are sealed with a sealing sheet and the sealing sheet is thermally cured, and FIG. 3C shows how a plurality of electronic device packages are obtained. FIG. 4 shows a plan view when evaluating contamination in an example. FIG. 5 shows a cross-sectional view when evaluating warpage in the example.

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 is the upper side (one side in the thickness direction), and the lower side of the paper is the lower side (the other side in the thickness direction).

As shown in FIGS. 1A and 3A, a sealing sheet 1 according to an embodiment of the present invention is used to seal an electronic element 51 with respect to an electronic member including a substrate 50 and an electronic element 51. This is a sheet for device sealing.

Further, the sealing sheet 1 is a component for manufacturing an electronic device package 7, which will be described later, and is not the electronic device package 7 itself. It does not include the board 50 to be mounted, and specifically, it is a component that can be distributed as a single component and can be used industrially.

Note that the sealing sheet 1 is not the sealing sheet 8 (FIGS. 3B and 3C) after sealing the electronic element 51, but is the 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) perpendicular to the thickness direction.

The sealing sheet 1 includes a first layer 2 and a second layer 3 in this order toward the top. That is, the sealing sheet 1 includes a first layer 2 and a second layer 3 disposed on the upper surface of the first layer 2. The sealing sheet 1 preferably consists of 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. The first layer 2 is a contact layer that is brought into contact with the electronic element 51 when the sealing sheet 1 attempts to seal the electronic element 51 (see FIG. 3A), as will be described later.

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, melts and flows, and hardens by further heating.

Further, the first thermosetting resin is in the B stage in the first layer 2 before sealing the electronic element 51, and is not in the C stage (that is, in a state before being completely cured).

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 types. From the viewpoint of heat resistance and the like, the first thermosetting resin is preferably an epoxy resin or a phenol resin, and more preferably a combination of an epoxy resin and a phenol resin.

Examples of the epoxy resin include bifunctional epoxy resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, modified bisphenol A epoxy resin, modified bisphenol F epoxy resin, biphenyl epoxy resin, and phenol novolak epoxy resin. Examples include trifunctional or higher functional epoxy resins such as cresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenylolethane type epoxy resin, and dicyclopentadiene type epoxy resin. These epoxy resins can be used alone or in combination of two or more. Preferably, a bifunctional epoxy resin, more preferably a bisphenol F type epoxy resin.

The epoxy equivalent of the epoxy resin is, for example, 230 g/eq. Below, preferably 210g/eq. or less, and for example, 10g/eq. Above, preferably 50g/eq. That's 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. It is.

Phenolic resin is a resin that hardens together with epoxy resin. Examples of the phenolic resin include trifunctional or higher functional phenolic resins such as phenol novolak 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, phenol novolak resin is used.

The hydroxyl equivalent of the phenol resin is, for example, 230 g/eq. Below, preferably 210g/eq. or less, and for example, 10g/eq. Above, preferably 50g/eq. That's 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. It is.

The ratio of the epoxy resin to the phenol resin is such that the total amount of hydroxyl groups in the phenol resin is, for example, 0.7 equivalent or more and 1.5 equivalent or less, preferably 0.7 equivalent or more and 1.5 equivalent or less, per 1 equivalent of epoxy group in the epoxy resin. The amount is adjusted to be 9 equivalents or more and 1.2 equivalents or less.

The proportion 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. % by mass or less. The proportion of the first thermosetting resin 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, based on the first composition. % or less.

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

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, Polycarbonate resin, thermoplastic polyimide resin, polyamide resin (6-nylon, 6,6-nylon, etc.), phenoxy resin, acrylic resin, saturated polyester resin (PET, etc.), polyamide-imide resin, fluororesin, styrene-isobutylene-styrene block Examples include copolymers. Preferably, acrylic resin is used.

As the acrylic resin, for example, an acrylic polymer obtained by polymerizing the monomer component using one or more types of (meth)acrylic acid alkyl ester having a linear or branched alkyl group as a monomer component, etc. can be mentioned. In addition, "(meth)acrylic" represents "acrylic and/or methacryl."

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, Examples include alkyl groups having 1 to 20 carbon atoms such as isodecyl, undecyl, lauryl, tridecyl, tetradecyl, stearyl, octadecyl, and dodecyl. Preferred is an alkyl group 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, acid anhydride monomers such as maleic anhydride and itaconic anhydride, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, (meth)acrylate, etc. 4-hydroxybutyl acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate or (4- Hydroxyl group-containing monomers such as hydroxymethylcyclohexyl)-methyl acrylate, for example styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl(meth) ) acrylate, (meth)acryloyloxynaphthalene sulfonic acid and other sulfonic acid group-containing monomers, for example, phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate, and styrene monomers such as acrylonitrile. These monomers can be used alone or in combination of two or more. Among these, carboxyl group-containing monomers are preferred.

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. If Tg is below the above upper limit, the sealing sheet 1 will easily penetrate into the gaps between the plurality of electronic elements 51 during sealing, resulting in excellent embeddability.

The glass transition point is obtained from the maximum value of the loss tangent (tan δ) measured using a dynamic viscoelasticity measurement device (DMA, frequency 1 Hz, temperature increase 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, 1,000,000 or less. Note that the weight average molecular weight is measured by gel permeation chromatography (GPC) based on a standard polystyrene equivalent value.

The proportion 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 at most 80% by mass, more preferably at most 65% by mass. The proportion of the first thermoplastic resin 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, based on the first composition. 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. This reduces the viscosity of the entire resin, improves resin fluidity, and improves embedding into the electronic element 51.

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 silane coupling agent. Examples include silane coupling agents, isocyanurate group-containing silane coupling agents, mercapto group-containing silane coupling agents, and preferably epoxy group-containing silane coupling agents.

Examples of epoxy group-containing silane coupling agents include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltrimethoxysilane. Examples include sidoxypropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane. Preferably, from the viewpoint of reactivity, 3-glycidoxypropyltriethoxysilane is used.

The proportion of the first silane coupling agent is, for example, 1% by mass or more, preferably 5% by mass or more, and, for example, 20% by mass or less, preferably 15% by mass or more, based on the first organic component. % by mass or less. The proportion of the first silane coupling agent 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 is 3% by mass or less.

The proportion of the first organic component 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, based on the first composition. , more preferably 20% by mass or less.

Examples of the first inorganic filler include quartz glass, talc, silica (such as fused silica and crystalline silica), alumina, aluminum nitride, silicon nitride, and boron nitride. These inorganic fillers can be used alone or in combination of two or more. Preferable examples of the inorganic filler include silica and alumina, more preferably silica.

The dimensions of the first inorganic filler are not particularly limited, and specifically, the average particle diameter 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. Moreover, two or more types of inorganic fillers having different average particle diameters can be used together. Such an inorganic filler is described, for example, in JP-A No. 2016-162909.

The proportion of the first inorganic filler 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 more, based on the first composition. % or less, preferably 90% by mass or less. If the ratio of the first inorganic filler is within the above range, the heat resistance reliability of the electronic device package 7 (described later) can be improved.

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

A curing accelerator is a catalyst (thermosetting catalyst) that accelerates 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), and organic phosphorus. Examples include compound compounds. Preferably, imidazole compounds are used. Also included are clathrate compounds in which the above imidazole compound is a guest and hydroxyisophthalic acid (HIPA) or the like is a host. Note that the clathrate compound is described in, for example, JP-A No. 2012-232994. These curing accelerators can be used alone or in combination of two or more types.

The ratio of the curing accelerator is, for example, 0.1 parts 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 black pigments such as carbon black. The average particle diameter 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, based on the first composition.

Furthermore, the first composition can contain additives other than the above-mentioned components in appropriate proportions.

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 disposed over the entire upper surface of the first layer 2. The second layer 3 is an exposed layer exposed to the outside (upper side) when the sealing sheet 1 seals the electronic element 51, as will be described later. Note that the second layer 3 is preferably a non-contact layer that does not contact 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 thermosetting resins similar to those exemplified for the first thermosetting resin. Preferably, the second thermosetting resin includes an epoxy resin and a phenol resin, and specifically, a combination of an epoxy resin and a phenol resin is included.

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 second thermosetting resin. It 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. It is.

The ratio of the epoxy resin to the phenol resin is such that the total amount of hydroxyl groups in the phenol resin is, for example, 0.7 equivalent or more and 1.5 equivalent or less, preferably 0.7 equivalent or more and 1.5 equivalent or less, per 1 equivalent of epoxy group in the epoxy resin. The amount is adjusted to be 9 equivalents or more and 1.2 equivalents or less.

The proportion 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. % by mass or less. The proportion of the second thermosetting resin 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, based on the second composition. % or less.

Examples of the second thermoplastic resin include the same thermoplastic resins as those exemplified for the first thermoplastic resin. Preferably, acrylic resin is used.

The proportion of the second thermoplastic resin 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% by mass or more, based on the second organic component. It is at most 30% by mass, preferably at most 30% by mass, more preferably at most 20% by mass. The proportion of the second thermoplastic resin 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 , 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 proportions (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. If the difference is within the above range, it is more certain that the lower surface of the first layer 2 is harder than the upper surface of the second layer 3, and that the elastic modulus of the second layer 3 after thermosetting is the same as that of the first layer 2. The elastic modulus can be made larger than the elastic modulus after thermosetting.

The second organic component may contain other organic components such as a second silane coupling agent in addition to the second thermosetting resin and the second thermoplastic resin. Preferably, the second organic component contains a second silane coupling agent. This reduces the viscosity of the entire resin, improves resin fluidity, and improves embedding into the electronic element 51.

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

The proportion of the second silane coupling agent is, for example, 1% by mass or more, preferably 5% by mass or more, and, for example, 20% by mass or less, preferably 15% by mass or more, based on the second organic component. % by mass or less. The proportion of the second silane coupling agent 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 is 3% by mass or less.

The proportion of the second organic component 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, based on the second composition. , more preferably 20% by mass or less.

Examples of the second inorganic filler include the same inorganic fillers as those exemplified for the first inorganic filler. Preferably, silica is used.

The proportion of the second inorganic filler 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 more, based on the second composition. % or less, preferably 90% by mass or less. If the ratio of the second inorganic filler is within the above range, the heat resistance reliability of the electronic device package 7 (described later) can be improved.

Further, the ratio [C2/C1] between 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 is, for example, 2.0 or less, preferably 1.3 or less. If the 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, pigment, etc. exemplified in the first composition in appropriate proportions.

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 is, 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, more preferably 4 or less. If the above ratio is within the above range, extrusion can be more reliably suppressed.

In the sealing sheet 1, the lower surface (the other surface in the thickness direction) of the first layer 2 is harder at 90° C. than the upper surface (one surface in the thickness direction) of the second layer 3. 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 depressed 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 placed on the heating table 10 with the first layer 2 facing upward, and the sealing sheet 1 is heated to 90°C. Then, the iron ball 11 is dropped onto the surface (lower surface) of the first layer 2. At this time, as shown in FIG. 2B, the amount (depth) of the depression formed on the surface of the first layer 2 is defined as D1. Similarly, the sealing sheet 1 is placed 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 sealing sheet 1 is heated to 90°C. An iron ball 11 is dropped onto the surface (upper surface). At this time, the amount (depth) of the depression formed on the surface of the second layer 3 is defined as D2. In this case, the amount of depression D1 in the first layer 2 is smaller than the amount of depression D2 in the second layer 3. That is, D1<D2 is satisfied.

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

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

The iron ball has a diameter of 18 mm, a weight of 21.7 g, and a falling height of 10 cm. Details will be explained in Examples.

If the first layer 2 is harder than the second layer 3 at 90°C, it is difficult to prevent the sealing sheet 1 from protruding when heating the sealing sheet 1 to seal the electronic element 1. 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 (i.e., the elastic modulus of the second layer 3 before thermosetting) is preferably the elastic modulus of the first layer 2 (i.e., the elastic modulus of the first layer 3 before thermosetting). 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 an indentation modulus, and is measured, for example, by conducting an indentation test on the surface of each layer (first layer or second layer) at room temperature (25°C). Use a microhardness tester. Details will be explained in Examples.

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

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

For example, a first varnish is prepared by dissolving and/or dispersing the first composition in a solvent (for example, methyl ethyl ketone, toluene, ethyl acetate, etc.), and this is applied to the first release sheet 4 shown by the phantom line. ,dry. As a result, the first layer 2 is prepared while being supported by the first release sheet 4.

A second varnish is prepared by dissolving and/or dispersing the second composition in a solvent, and this is applied to the second release sheet 5 shown by the phantom line and dried. In this way, the second layer 3 is prepared while being supported by the second release sheet 5.

Alternatively, the first layer 2 and/or the second layer 3 can be prepared by kneading and extrusion without preparing a varnish.

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

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

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

As shown in FIG. 3A, first, an electronic device 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 includes various electronic elements, such as a hollow electronic element, a semiconductor element, and the like. A plurality of electronic elements 51 are mounted on the upper surface of the substrate 50 so as to face each other. 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 surface 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 (such as a die-bonding film) not shown.

To prepare the electronic element 51, an electronic element mounting board 55 including the electronic element 51 and a 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 that surrounds the plurality of electronic elements 51 in a plan view. The substrate 50 has terminals (not shown) on its upper surface that are electrically connected to the electronic elements 51. The substrate 50 is made of, for example, a ceramic plate, a glass epoxy plate, or the like.

Next, a sealing sheet 1 is prepared.

The size of the sealing sheet 1 is adjusted to a size that allows the plurality of electronic devices 51 to be sealed together. In other words, when projected in the thickness direction, the size of the sealing sheet 1 is adjusted to include all of the plurality of electronic devices 51. It has a certain quality.

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 using a flat plate press 97 having a lower plate 98 and an upper plate 99 shown by the imaginary lines in FIG. 3B.

The electronic element mounting board 55 is placed 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 placed on the electronic element mounting board 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 upward. 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 is, for example, 10 MPa or less, preferably 5 MPa or less. The pressing time is, for example, 0.3 minutes or more, preferably 0.5 minutes or more, and is, for example, 10 minutes or less, preferably 5 minutes or less.

Note that in the heat press, in addition to the flat plate press 97 (imaginary 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 therein. In other words, the plurality of electronic elements 51 are embedded in the sealing sheet 1.

Specifically, the first layer 2 covers the upper surface and side surfaces 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 in accordance with the outer shape of the electronic element 51.

On the other hand, the lower surface of the second layer 3 deforms in accordance with the deformation of the first layer 2, while the upper surface of the second layer 3 maintains a flat shape because it is pressed against the upper plate 99.

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 bottom surface of the lower plate 98 or the substrate 50, and contamination of the surroundings is suppressed.

Thereafter, 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 concave portion that corresponds to the electronic element 51 and opens downward.

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

Note that if the second release sheet 5 supports the second layer 3 before thermosetting the sealing sheet 1, the second release sheet 5 is peeled from the second layer 3. Alternatively, the second release sheet 5 can be peeled off from the second layer 3 before the electronic element 51 is sealed with the sealing sheet 1.

The heating temperature (cure temperature) is, for example, 100°C or higher, preferably 120°C or higher, and is, 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 is, for example, 180 minutes or less, preferably 120 minutes or less.

To heat-cure the sealing sheet 1, the sealing sheet 1, electronic element 51, and substrate 50 are taken out from the flat plate press 97 and placed in, for example, a heating furnace. In addition, the sealing sheet 1 can also be thermally cured using the heat source provided in the flat plate press 97 without taking out the sealing sheet 1, the electronic element 51, and the board|substrate 50 from the flat plate press 97.

If necessary, then a mark is applied (marked) to the upper surface of the second layer 3 located above the plurality of electronic elements 51 by laser irradiation or the like. The mark includes information (product information, lot number, etc.) regarding the electronic device package 7, which will be described next.

In the sealing sheet 8 (the sealing sheet 1 after thermosetting), the elastic modulus of the second layer 3 (i.e., the elastic modulus of the second layer 3 after thermosetting) is the same as the elastic modulus of the first layer 2 (i.e., the elastic modulus of the second layer 3 after thermosetting). , the elastic modulus of the first layer 2 after thermosetting).

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 is, 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 less than 0.5 GPa, and is, for example, more than 0.01 GPa, preferably more than 0.1 GPa.

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 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, warping of the electronic element package 7 can be suppressed.

Furthermore, since the second layer 3 has a relatively high modulus of elasticity, marking of the electronic device package 7 is easy. Furthermore, grinding for reducing the height of the package can be facilitated, and wear of the grinding wheel can be reduced.

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

Thereafter, the electronic element package 7 is mounted on another board.

In the sealing sheet 1 shown in FIG. 1A (the sheet before forming the sealing sheet 8), 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, making it difficult to wet and spread. Therefore, protrusion of the sealing sheet 1 can be suppressed. Therefore, contamination around the electronic device package 7 can be suppressed. In other words, it has excellent low contamination properties. Furthermore, since the first layer 2 is difficult to protrude in the sealed state (before curing and dicing) shown in FIG. can be improved.

Moreover, in this 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, warpage of the electronic element package 7 can be suppressed. That is, the electronic element package 7 includes the substrate 50 and the second layer 3, and the first layer 2 is sandwiched between them. Therefore, even if the electronic device package 7 is left under high temperature, the electronic device package 7 has a sandwich structure including the substrate 50 (for example, a ceramic substrate) having a relatively high elastic modulus and the second layer 3. Therefore, the occurrence of warping of the electronic element package 7 can be suppressed. Furthermore, the laser marking property on the second layer 3 is good. Furthermore, since there is little dimensional change, reliability in thermal cycle tests and the like is good.

In addition, in this 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 can be further suppressed. can do. Furthermore, since the second layer 3 (upper layer) can be plastically deformed, the influence of unevenness on the top surface of the electronic device 51 can be reduced, and as a result, the top surface of the electronic device 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. Furthermore, since the proportion of the first thermoplastic resin is high, the sheet has good flexibility, has good handling properties during sealing, and can suppress the occurrence of cracks.

Examples and Comparative Examples are shown below to further specifically explain the present invention. Note that the present invention is not limited to the Examples and Comparative Examples. In addition, the specific numerical values of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description are the corresponding blending ratios ( Content percentage), physical property values, parameters, etc. can be replaced with the upper limit (value defined as "less than" or "less than") or lower limit (value defined as "more than" or "exceeding"). can.

Each component used in Examples and Comparative Examples is shown below.
YSLV-80XY: Epoxy resin (bisphenol F type epoxy resin), epoxy equivalent: 200 g/eq. , Softening point: 80°C, LVR8210DL manufactured by Nippon Steel Chemical Co., Ltd.: Phenol resin (novolak type phenol resin), hydroxyl group equivalent: 104 g/eq. , Softening point: 60°C, Gun-ei Chemical Co., Ltd. HME-2006M: Acrylic resin (methyl ethyl ketone solution of 20% by mass of acrylic acid ester polymer containing carboxyl group, weight average molecular weight: approximately 600,000, Tg: -30°C, Negami) SG-70L manufactured by Kogyo Co., Ltd.: Acrylic resin (methyl ethyl ketone solution containing 12.5% by mass of acrylic acid ester polymer containing carboxyl groups, weight average molecular weight: approximately 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 particle size: 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 values in Table 1 indicate the 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.

The first varnish and the second varnish were each 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, a first layer 2 with a thickness of 65 μm and a second layer 3 with a thickness of 195 μm were prepared.

After that, the first layer 2 and the second layer 3 were bonded together. In this way, a sealing sheet 1 including a first layer 2 (lower layer) and a second layer 3 (upper layer) was produced.

Examples 2-3 and Comparative Examples 1-4
Sealing sheet 1 was produced 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 and lower surfaces of the sealing sheet (50 mm×50 mm) of each Example and each Comparative Example. 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 bottom and the second layer was on the top. It was dropped onto the top surface of the sealing sheet. After falling, the iron ball 11 was left for 5 minutes and removed (see FIGS. 2A and 2B).

The amount of depression D2 on the upper surface of the sealing sheet (surface on the second layer side) was measured using a 3CCD color confocal microscope ("MC-1000A", manufactured by Lasertec Corporation) under the conditions of confocal mode and 5x magnification. It was measured.

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

These results are shown in Table 2.

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

Moreover, the sealing sheets of each Example and each Comparative Example were heated at 150° C. for 1 hour to completely cure them. The indentation modulus of the first layer and second layer of this cured sheet (sealing sheet) was determined in the same manner as above. These results are shown in Table 2.

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

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

X [%] = (A [mm] / 80 [mm]) × 100
If X is 100% or more and 105% or less, evaluate as ○; if X exceeds 105% and 110% or less, evaluate as △; if X exceeds 110%, evaluate as × rated it as. The results are shown in Table 2.

<Evaluation of warpage suppression>
A ceramic plate 30 measuring 100 mm x 100 mm x 200 μm in thickness was prepared. A sealing sheet (80 mm x 80 mm x 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 the sealing sheet, and a pressure of 0.1 MPa was applied using a vacuum plate press machine. , 90° C., and 1 minute to obtain a laminate 31.

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

The case where the amount of warpage was 5 mm or less was evaluated as ○, and the case where the amount of warp exceeded 5 mm was evaluated as ×. The results are shown in Table 2.

1 Sealing sheet 2 First layer 3 Second layer 8 Sealing sheet 50 Substrate 51 Electronic element

Claims (3)

It is a sealing sheet for sealing electronic devices,
When sealing the electronic device, a first layer in contact with the electronic device 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 each have thermosetting properties,
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 in the sealing sheet at 90° C., and the sealing sheet is arranged such that the first layer is on the upper side. A first iron ball drop test in which an iron ball is dropped onto the surface of the first layer after placing it on a heating table and heating the sealing sheet to 90°C (diameter of the iron ball: 18 mm, drop height: 10 cm) The amount of depression formed on the other surface in the thickness direction of the first layer is such that the sealing sheet is placed on the heating table with the second layer facing upward, and the sealing sheet is placed on the heating table with the second layer facing upward. In a second iron ball drop test (diameter of the iron ball: 18 mm, drop height: 10 cm) in which an iron ball was dropped onto the surface of the second layer after heating to 90°C, the thickness direction of the second layer was smaller than the amount of dent formed in the direction,
A sealing sheet, wherein 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 includes a first organic component containing a first thermosetting resin and a first thermoplastic resin,
The second layer includes a second organic component containing a second thermosetting resin and a second thermoplastic resin,
The seal according to claim 1 or 2, characterized in that 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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