JP6883937B2 - Manufacturing method of sealing sheet and hollow package - Google Patents

Description

The present invention relates to a sealing sheet and a hollow package.

In recent years, development of microelectronic devices called MEMS such as SAW (Surface Acoustic Wave) filters, CMOS (Complementary Metal Oxide Sensor) sensors, and acceleration sensors has been promoted. Each package containing these electronic devices generally has a hollow structure for propagating surface acoustic waves, maintaining an optical system, and ensuring the mobility of movable members of the electronic device. This hollow structure is often provided as a space between the substrate and the element. At the time of sealing, it is necessary to seal while maintaining the hollow structure so as to secure the operation reliability of the movable member and the connection reliability of the element. For example, Patent Document 1 describes a technique for sealing an element using a resin composition sheet.

Japanese Unexamined Patent Publication No. 2009-91389

As shown in FIGS. 13 and 14, the laminate 531 having the device mount 502 and the sheet-shaped thermosetting composition 511 arranged on the device mount 502 is pressurized and mounted on the substrate 522 and the substrate 522. A hollow package can be produced by a method including a step of forming a sealing body 532 having a thermosetting composition 511 covering the electronic device 523 and the electronic device 523, a step of heating the sealing body 532, and the like. The device mount 502 has a substrate 522 and an electronic device 523 mounted on the substrate 522. A space 525 is provided between the substrate 522 and the electronic device 523.

In such a manufacturing method, it is desired to reduce the amount of the thermosetting composition 511 that enters the space 525 between the substrate 522 and the electronic device 523. Further, since the cured product formed by curing the thermosetting composition 511 is heat-shrinked, the substrate 522 may be warped. The warp of the substrate 522 causes a transfer failure.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to reduce the amount of the thermosetting composition entering the space between the substrate and the electronic device, and reduce the warp of the substrate. It is to provide a sealing sheet that can be used. Another object of the present invention is to provide a method for manufacturing a hollow package capable of reducing the amount of the thermocurable composition entering the space between the substrate and the electronic device and reducing the warp of the substrate. is there.

The present invention relates to a sealing sheet used to manufacture a hollow package. A thermosetting composition in which the sealing sheet forms a sheet is provided. The thermosetting composition contains an inorganic filler and residual components. The residual component contains an acrylic polymer. The content of the acrylic polymer in the residual component is 40% by weight or more. The cured product obtained by curing the thermosetting composition has a sea-island structure including a matrix portion and a domain portion. The matrix part contains an acrylic polymer as a main component. The matrix part is softer than the domain part. The storage elastic modulus of the cured product at 25 ° C. is 5 × 10 ⁷ Pa to 5 × 10 ^{9 Pa.}

When the content of the acrylic polymer in the residual component is 40% by weight or more, the storage elastic modulus of the cured product can be reduced. Storage modulus at 25 ° C. of the cured product by not more than 5 × 10 9 ^Pa, can be reduced warpage of the substrate. By being able to form a sea-island structure that includes a domain part and a matrix part that is softer than the domain part, it is possible to control the flow and reduce the amount of thermosetting composition that enters the space between the substrate and the electronic device. it can.

It is preferable that the residual component further contains a thermosetting resin. It is preferable that the domain portion contains a thermosetting resin as a main component.

The content of the inorganic filler in the thermosetting composition is preferably 55% by volume to 85% by volume. When it is 55% by volume or more, the coefficient of linear expansion of the cured product can be brought close to the coefficient of linear expansion of the substrate, and the warp of the substrate can be effectively reduced.

The present invention also relates to a method for producing a hollow package, which comprises a step of pressurizing a device mount and a laminate having a thermosetting composition arranged on the device mount. The device mount comprises a substrate and electronic devices mounted on the substrate.

It is the schematic sectional drawing of the sealing sheet which concerns on Embodiment 1. FIG. It is a TEM observation image of the cross section of the cured product. The lower observation image is a partially enlarged image of the upper observation image. It is an AFM phase image of the cross section of a cured product. In order to clearly show the sea-island structure, a cured product obtained by curing a thermosetting composition having an epoxy resin, a phenol resin, an acrylic polymer and a curing accelerator and without a filler and a pigment was observed. It is a TEM observation image of the cross section of the cured product. In order to clearly show the sea-island structure, a cured product obtained by curing a thermocurable composition having an epoxy resin, a phenol resin, an acrylic polymer and a curing accelerator and without a filler and a pigment was observed. It is a schematic sectional view of a laminated body and the like. It is the schematic sectional drawing of the process of hot-pressing a laminated body. It is the schematic sectional drawing of the sealing body. It is a schematic sectional view of a structure. It is the schematic sectional drawing of the hollow package. It is the schematic sectional drawing of the sealing sheet which concerns on modification 1. FIG. It is a front schematic view of the laminated body for test. It is a front schematic view of the laminated body for test. It is the schematic sectional drawing of the hollow package manufacturing process. It is the schematic sectional drawing of the hollow package manufacturing process.

Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited to these embodiments.

[Embodiment 1]
(Sealing sheet 1)
The sealing sheet 1 will be described.

As shown in FIG. 1, the thermosetting composition 11 in which the sealing sheet 1 forms a sheet is provided. The sealing sheet 1 further includes a separator 12. Specifically, the sealing sheet 1 includes a separator 12 and a thermosetting composition 11 arranged on the separator 12. Examples of the separator 12 include a polyethylene terephthalate (PET) film and the like. The separator 12 is preferably one that has undergone a mold release treatment.

The thermosetting composition 11 contains an inorganic filler and residual components.

Examples of the residual component include a resin component, a curing accelerator, a pigment and the like.

Examples of the resin component include acrylic polymers and thermosetting resins.

In the thermosetting composition 11, it is preferable that the acrylic polymer and the thermosetting resin are compatible with each other. When they are compatible with each other, segregation of the thermosetting resin and segregation of the acrylic polymer do not occur, so that the warp of the substrate can be reduced. The fact that the acrylic polymer and the thermosetting resin are compatible means that the phase-separated structure of the acrylic polymer and the thermosetting resin is not observed in the observation image observed by a transmission electron microscope (TEM). Say.

Acrylic polymers are preferable because they are easily flexible and have good dispersibility with epoxy resins. Of these, a thermoplastic acrylic polymer is preferable.

The acrylic polymer is not particularly limited, and contains one or more esters of acrylic acid or methacrylic acid having a linear or branched alkyl group having 30 or less carbon atoms, particularly 4 to 18 carbon atoms. Examples thereof include a polymer (acrylic copolymer). Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, t-butyl group, isobutyl group, amyl group, isoamyl group, hexyl group, heptyl group, cyclohexyl group and 2-ethylhexyl. Examples thereof include a group, an octyl group, an isooctyl group, a nonyl group, an isononyl group, a decyl group, an isodecyl group, an undecyl group, a lauryl group, a tridecyl group, a tetradecyl group, a stearyl group, an octadecyl group, or a dodecyl group.

The other monomer forming the polymer is not particularly limited, and is, for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like. Carboxyl group-containing monomer, acid anhydride monomer such as maleic anhydride or itaconic anhydride, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxy (meth) acrylate Butyl, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate or (4-hydroxymethylcyclohexyl)- Hydroxyl group-containing monomers such as methyl acrylate, styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropansulfonic acid, (meth) acrylamide propanesulfonic acid, sulfopropyl (meth) acrylate or (meth) ) Examples thereof include a sulfonic acid group-containing monomer such as acryloyloxynaphthalene sulfonic acid and a phosphoric acid group-containing monomer such as 2-hydroxyethylacryloyl phosphate. Among them, at least one of a carboxyl group-containing monomer, a glycidyl group (epoxy group) -containing monomer, and a hydroxyl group-containing monomer is contained from the viewpoint of increasing the viscosity of the thermosetting composition 11 by reacting with the epoxy resin. Is preferable.

The acrylic polymer preferably has a functional group. As the functional group, a carboxyl group (-COOH), an epoxy group, a hydroxyl group, an amino group, and a mercapto group are preferable, and a carboxyl group is more preferable, because the sea-island structure can be easily formed.

The acid value of the acrylic polymer is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, still more preferably 10 mgKOH / g or more. When it is 1 mgKOH / g or more, the domain portion can be made small, and the flow of the thermosetting composition 11 can be regulated. On the other hand, the acid value of the acrylic polymer is preferably 100 mgKOH / g or less, more preferably 60 mgKOH / g or less, still more preferably 50 mgKOH / g or less, and particularly preferably 40 mgKOH / g or less. When it is 100 mgKOH / g or less, the storage stability of the thermosetting composition 11 can be relatively well maintained.
The acid value can be measured by the neutralization titration method specified in JIS K 0070-1992.

The weight average molecular weight of the acrylic polymer is preferably 400,000 or more, more preferably 500,000 or more. When it is 400,000 or more, the viscosity of the acrylic polymer is not too low, so that it is easy to handle. On the other hand, the weight average molecular weight of the acrylic polymer is preferably 2 million or less, more preferably 1.5 million or less. When it is 2 million or less, the viscosity of the acrylic polymer is not too high, so that it is easy to handle.
The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

The Tg of the acrylic polymer is preferably −70 ° C. or higher, more preferably −60 ° C. or higher, and even more preferably −50 ° C. or higher. When the temperature is −70 ° C. or higher, the storage elastic modulus of the thermosetting composition 11 at the molding temperature is not too low, so that the flow of the thermosetting composition 11 can be easily controlled. On the other hand, the Tg of the acrylic polymer is preferably 20 ° C. or lower, more preferably 0 ° C. or lower. When the temperature is 20 ° C. or lower, the storage elasticity of the thermosetting composition 11 at the molding temperature is not too high, so that the flow of the thermosetting composition 11 can be easily controlled.

In the present specification, the glass transition temperature of the acrylic polymer refers to a theoretical value obtained by the Fox formula.
Another method for determining the glass transition temperature is to determine the glass transition temperature of the acrylic polymer based on the temperature at the maximum heat absorption peak measured by a differential scanning calorimeter (DSC). Specifically, the sample to be measured is about 50 ° C. higher than the predicted glass transition temperature (predicted temperature) of the sample using a differential scanning calorimeter (“Q-2000” manufactured by TA Instruments). After heating at the temperature for 10 minutes, it is cooled to a temperature 50 ° C. lower than the predicted temperature for pretreatment, and then the temperature is raised at a temperature rising rate of 5 ° C./min under a nitrogen atmosphere to measure the heat absorption start point temperature. This is referred to as the glass transition temperature.

The content of the acrylic polymer in the residual component is 40% by weight or more, preferably 50% by weight or more, more preferably 55% by weight or more, still more preferably 60% by weight or more. Examples of the lower limit of the content of the acrylic polymer in the residual component include 65% by weight, 70% by weight, 75% by weight and the like. On the other hand, the content of the acrylic polymer in the residual component is preferably 95% by weight or less, more preferably 90% by weight or less.

The thermosetting resin is not particularly limited, but an epoxy resin and a phenol resin are preferable.

The epoxy resin is not particularly limited. For example, triphenylmethane type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, modified bisphenol A type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, modified bisphenol F type epoxy resin, dicyclopentadiene type. Various epoxy resins such as epoxy resin, phenol novolac type epoxy resin, and phenoxy resin can be used. These epoxy resins may be used alone or in combination of two or more.

From the viewpoint of ensuring the reactivity of the epoxy resin, an epoxy equivalent of 150 to 250, a softening point or a solid at room temperature of 50 to 130 ° C. is preferable. Of these, a triphenylmethane type epoxy resin, a cresol novolac type epoxy resin, and a biphenyl type epoxy resin are more preferable from the viewpoint of reliability. Further, a bisphenol F type epoxy resin is preferable because it can impart flexibility to the thermosetting composition 11.

The phenol resin is not particularly limited as long as it causes a curing reaction with the epoxy resin. For example, phenol novolac resin, phenol aralkyl resin, biphenyl aralkyl resin, dicyclopentadiene type phenol resin, cresol novolac resin, resol resin and the like are used. These phenol resins may be used alone or in combination of two or more.

From the viewpoint of reactivity with the epoxy resin, the phenol resin preferably has a hydroxyl group equivalent of 70 to 250 and a softening point of 50 to 110 ° C. From the viewpoint of high curing reactivity, a phenol novolac resin can be preferably used. Further, from the viewpoint of reliability, those having low hygroscopicity such as phenol aralkyl resin and biphenyl aralkyl resin can also be preferably used.

From the viewpoint of curing reactivity, the mixing ratio of the epoxy resin and the phenol resin is such that the total number of hydroxyl groups in the phenol resin is 0.7 to 1.5 equivalents with respect to 1 equivalent of the epoxy groups in the epoxy resin. It is preferably 0.9 to 1.2 equivalents.

The content of the thermosetting resin in the residual component is preferably 10% by weight or more, more preferably 15% by weight or more, still more preferably 17% by weight or more, and particularly preferably 20% by weight or more. On the other hand, the content of the thermosetting resin in the residual component is preferably 55% by weight or less, more preferably 45% by weight or less, still more preferably 40% by weight or less, and particularly preferably 30% by weight or less.

The curing accelerator is not particularly limited as long as it promotes the curing of the epoxy resin and the phenol resin, and is, for example, 2-methylimidazole (trade name; 2MZ) and 2-undecylimidazole (trade name; C11-Z). ), 2-Heptadecylimidazole (trade name: C17Z), 1,2-dimethylimidazole (trade name: 1.2DMZ), 2-ethyl-4-methylimidazole (trade name: 2E4MZ), 2-phenylimidazole (trade name) Name; 2PZ), 2-phenyl-4-methylimidazole (trade name: 2P4MZ), 1-benzyl-2-methylimidazole (trade name: 1B2MZ), 1-benzyl-2-phenylimidazole (trade name: 1B2PZ), 1-Cyanoethyl-2-methylimidazole (trade name: 2MZ-CN), 1-cyanoethyl-2-undecylimidazole (trade name: C11Z-CN), 1-cyanoethyl-2-phenylimidazolium trimerite (trade name) 2PZCNS-PW), 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine (trade name; 2MZ-A), 2,4-diamino-6- [ 2'-Undecylimidazolyl- (1')] -ethyl-s-triazine (trade name; C11Z-A), 2,4-diamino-6- [2'-ethyl-4'-methylimidazolyl- (1') )]-Ethyl-s-triazine (trade name; 2E4MZ-A), 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine isocyanuric acid adduct (trade name) 2MA-OK), 2-phenyl-4,5-dihydroxymethylimidazole (trade name: 2PHZ-PW), 2-phenyl-4-methyl-5-hydroxymethylimidazole (trade name: 2P4MHZ-PW) and other imidazoles. Examples include system curing accelerators (both manufactured by Shikoku Kasei Kogyo Co., Ltd.).

Among them, an imidazole-based curing accelerator is preferable because it has a good curing promoting ability and a cured product having a high Tg can be obtained. 2-Phenyl-4,5-dihydroxymethylimidazole, 2,4-diamino-6- [ 2'-Ethyl-4'-methylimidazolyl- (1')]-ethyl-s-triazine is more preferred, and 2-phenyl-4,5-dihydroxymethylimidazole is even more preferred.

The content of the curing accelerator is preferably 0.2 parts by weight or more, more preferably 0.5 parts by weight or more, still more preferably 0.8 parts by weight or more, based on 100 parts by weight of the total of the epoxy resin and the phenol resin. Is. The content of the curing accelerator is preferably 5 parts by weight or less, more preferably 2 parts by weight or less, based on 100 parts by weight of the total of the epoxy resin and the phenol resin.

The pigment is not particularly limited, and examples thereof include carbon black.

Examples of the inorganic filler include quartz glass, talc, silica (molten silica, crystalline silica, etc.), alumina (aluminum oxide), boron nitride, aluminum nitride, silicon dioxide, and the like. Of these, silica is preferable because it can satisfactorily reduce the coefficient of thermal expansion. As the silica, molten silica is preferable, and spherical fused silica is more preferable because of its excellent fluidity. Further, because of high thermal conductivity, a thermally conductive filler is preferable, and alumina, boron nitride, and aluminum nitride are more preferable. The inorganic filler is preferably an electrically insulating filler.

Silica, alumina and the like may be used in combination as the inorganic filler.

The average particle size of the inorganic filler is preferably 0.5 μm or more, more preferably 1 μm or more. When it is 0.5 μm or more, it is easy to obtain the flexibility and flexibility of the thermosetting composition 11. The average particle size of the filler is preferably 30 μm or less, more preferably 10 μm or less. When it is 30 μm or less, the filler can be easily filled.
The average particle size can be derived, for example, by using a sample arbitrarily extracted from the population and measuring it with a laser diffraction / scattering type particle size distribution measuring device.

As the inorganic filler, it is preferable to use a surface-treated inorganic filler pretreated with a silane coupling agent. As a result, the wettability of the inorganic filler with respect to the resin component can be improved, and the dispersibility of the inorganic filler can be improved. As the inorganic filler, it is preferable to use an untreated inorganic filler that has not been pretreated with a surface-treated inorganic filler and a silane coupling agent.

As the silane coupling agent, for example, a compound having a methacryloxy group or an acryloxy group can be preferably used. The methacryloxy and acryloxy groups are non-reactive with thermosetting resins. By using a compound having a methacryloxy group or an acryloxy group as a silane coupling agent, it is possible to suppress an increase in the minimum viscosity of the thermosetting composition 11 due to the reaction between the silane coupling agent and the thermosetting resin.

A compound having a methacryloxy group or an acryloxy group preferably further has an alkoxy group having 1 to 6 carbon atoms. Examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group and an ethoxy group.

Examples of the compound having a methacryloxy group or an acryloxy group include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and methacryloxy. Examples thereof include octyl trimethoxysilane and methacryloxyoctyl ethoxysilane. Of these, 3-methacryloxypropyltrimethoxysilane is preferable from the viewpoint of reactivity and cost.

It is preferable that at least peak A and peak B are present in the particle size distribution of the inorganic filler. Specifically, it is preferable that the peak A exists in the particle size range of 0.01 μm to 10 μm and the peak B exists in the particle size range of 1 μm to 100 μm. Since the inorganic filler forming the peak A can be filled between the inorganic fillers forming the peak B, the inorganic filler can be highly filled.

It is more preferable that the peak A exists in the particle size range of 0.1 μm or more. It is more preferable that the peak A exists in the particle size range of 1 μm or less.

It is more preferable that the peak B exists in a particle size range of 3 μm or more. It is more preferable that the peak B exists in the particle size range of 10 μm or less.

In the particle size distribution of the inorganic filler, peak C and the like other than peak A and peak B may be present.

The particle size distribution of the inorganic filler can be measured by the following method.

Method for Measuring Particle Size Distribution of Inorganic Filler The thermosetting composition 11 is placed in a crucible and heated strongly to incinerate the thermosetting composition 11. The obtained ash is dispersed in pure water and ultrasonically treated for 10 minutes, and the particle size distribution (volume standard) is used using a laser diffraction / scattering particle size distribution measuring device (Beckman Coulter, "LS 13 320"; wet method). ).

The content of the inorganic filler in the thermosetting composition 11 is preferably 55% by volume or more, more preferably 60% by volume or more, still more preferably 70% by volume or more. By increasing the content of the inorganic filler, it is possible to bring the coefficient of linear expansion of the cured product closer to the coefficient of linear expansion of the substrate. On the other hand, the content of the inorganic filler in the thermosetting composition 11 is preferably 85% by volume or less, more preferably 80% by volume or less. When it is 85% by volume or less, it is easy to mold into a sheet.

The content of the inorganic filler can also be explained in units of "% by weight". Typically, the silica content will be described in units of "% by weight".
Since the specific gravity of silica is usually 2.2 g / cm ³ , the preferable range of the silica content (% by weight) is as follows, for example.
That is, the content of silica in the thermosetting composition 11 is preferably 60% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more. On the other hand, the content of silica in the thermosetting composition 11 is preferably 91% by weight or less, more preferably 88% by weight or less.

Since the specific gravity of alumina is usually 3.9 g / cm ³ , the preferable range of the alumina content (% by weight) is as follows, for example.
That is, the content of alumina in the thermosetting composition 11 is preferably 72% by weight or more, more preferably 80% by weight or more, still more preferably 87% by weight or more. On the other hand, the content of alumina in the thermosetting composition 11 is preferably 95% by weight or less, more preferably 93% by weight or less.

The cured product obtained by curing the thermosetting composition 11 has a sea-island structure.

FIG. 2 shows an observation image obtained by observing the cured product with a transmission electron microscope (TEM). In the observation image placed on the left of the upper row, the dark part, which is the matrix part (hereinafter, also referred to as "sea phase"), and the domain part (hereinafter, also referred to as "island phase") are located above the observation image. You can see a light part of a certain color. In the observation image arranged on the right side of the upper row, a dark part of the matrix part and a light color part of the domain part can be confirmed at the upper part of the observation image. The circular object is a filler.

As shown in FIG. 2, the cured product has a sea-island structure including a matrix portion and a domain portion. The matrix part is softer than the domain part. The cured product comprises a filler dispersed in the matrix portion.
The cured product can be obtained, for example, by heating the thermosetting composition 11 at 150 ° C. for 1 hour.

The softness of the matrix part and the domain part can be known by, for example, an interatomic force microscope (AFM).

In FIG. 3, a light-colored portion (non-black portion) is a portion having a small phase delay. The portion with a small phase delay has low adsorptivity and is hard. On the other hand, the dark part is the part where the phase delay is large. The portion having a large phase delay has high adsorptivity and is soft.

By being able to form a sea-island structure including a domain part and a matrix part softer than the domain part, it is possible to control the flow, and the amount of the thermosetting composition 11 that enters the space between the substrate and the electronic device Can be reduced.

The matrix portion contains an acrylic polymer as a main component. The domain portion contains a thermosetting resin as a main component.

By comparing the AFM observation result of the cured product with the observation result of the transmission electron microscope (TEM), it can be clarified that the matrix portion contains the acrylic polymer as a main component. It can be clarified that the domain portion contains a thermosetting resin as a main component.

For reference, FIG. 4 shows a TEM observation image of the cured product used in FIG. The dark-colored portion is a low-luminance region and is a portion containing an acrylic polymer as a main component.

By adjusting the type of functional group of the acrylic polymer, the content of the acrylic polymer, and the like, a thermosetting composition 11 capable of forming a sea-island structure including a domain portion and a matrix portion softer than the domain portion can be obtained.

By increasing the content of the acrylic polymer, a matrix portion softer than the domain portion can be easily formed.

The maximum particle size of the domain portion is preferably 0.01 μm or more, more preferably 0.03 μm or more, and further preferably 0.05 μm or more. When it is 0.01 μm or more, the flow of the thermosetting composition 11 can be regulated. On the other hand, the maximum particle size of the domain portion is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less, still more preferably 1 μm or less, still more preferably 0.8 μm or less, still more preferably 0.5 μm or less. .. When it is 5 μm or less, it is possible to impart a thixotropy-like action, and the flow of the thermosetting composition 11 can be regulated.

The maximum particle size of the domain portion can be controlled by the amount of functional groups of the acrylic polymer. For example, the maximum particle size of the domain portion can be reduced by blending an acrylic polymer having a large amount of functional groups. The compatibility between the thermosetting resin and the acrylic polymer also affects the maximum particle size of the domain portion. However, the amount of functional groups in the acrylic polymer has a greater effect.

The maximum particle size of the domain portion is the maximum distance between two points on the contour of the domain portion in the observation image observed by a transmission electron microscope (TEM). The maximum particle size of the domain portion can be calculated by averaging the measured values obtained by observing 100 domain portions. When a plurality of domain parts are aggregated or aggregated, those having continuous contours are treated as one domain part.

The storage elastic modulus of the cured product at 25 ° C. is 5 × 10 ⁷ Pa or more, preferably 9 × 10 ⁷ Pa or more. When it is 5 × 10 ⁷ Pa or more, the electronic device can be well sealed. On the other hand, the storage elastic modulus of the cured product at 25 ° C. is 5 × 10 ⁹ Pa or less, preferably 1 × 10 ⁹ Pa or less, and more preferably 1 × 10 ⁸ Pa or less. When it is 5 × 10 ⁹ Pa or less, the stress generated by returning the cured product to room temperature can be reduced, and the warpage of the substrate can be reduced. In addition, the warpage of the substrate generated by reflow heating can be reduced.
The storage elastic modulus can be measured by the method described in Examples.

The storage elastic modulus of the cured product can be controlled by the content of the acrylic polymer, the content of the inorganic filler, and the like.

The method for producing the sealing sheet 1 is not particularly limited. For example, a resin for forming the thermosetting composition 11 is dissolved and dispersed in an appropriate solvent to prepare a varnish, and the varnish is placed on the separator 12. The sealing sheet 1 can be obtained by applying the coating film to a predetermined thickness to form a coating film and then drying the coating film under predetermined conditions. The coating method is not particularly limited, and examples thereof include roll coating, screen coating, and gravure coating. The drying conditions are, for example, a drying temperature of 70 to 160 ° C. and a drying time of 1 to 30 minutes. Further, a varnish is applied on a separator different from the separator 12 to form a coating film, and the coating film is dried to form a thermosetting composition 11, and then the thermosetting composition 11 is pasted on the separator 12. The method of matching is also suitable. Examples of the solvent include methyl ethyl ketone, ethyl acetate, toluene and the like.

The thermosetting composition 11 is also preferably produced by kneading extrusion. As a result, a thermosetting composition 11 that can be easily formed into a sheet, has few voids, and has a uniform thickness can be obtained. As a method for producing by kneading extrusion, for example, a method of plastically processing a kneaded product obtained by kneading each of the above components (for example, an inorganic filler, an acrylic polymer, etc.) into a sheet shape is preferable. By manufacturing by kneading extrusion, the inorganic filler can be highly filled.

Specifically, a kneaded product is prepared by melt-kneading a thermosetting resin, a curing accelerator, an acrylic polymer, an inorganic filler, etc. with a known kneader such as a mixing roll, a pressure kneader, or an extruder. The kneaded product is plastically processed into a sheet. As the kneading condition, the upper limit of the temperature is preferably 140 ° C. or lower, more preferably 130 ° C. or lower. The lower limit of the temperature is preferably equal to or higher than the softening point of each of the above-mentioned components, for example, 30 ° C. or higher, preferably 50 ° C. or higher. The kneading time is preferably 1 to 30 minutes. Further, the kneading is preferably performed under reduced pressure conditions (under a reduced pressure atmosphere), and the pressure under reduced pressure conditions is, for example, 1 × 10 ^{-4 to} 0.1 kg / cm ² .

The kneaded product after melt-kneading is preferably plastically worked in a high temperature state without cooling. The plastic working method is not particularly limited, and examples thereof include a flat plate pressing method, a T-die extrusion method, a screw die extrusion method, a roll rolling method, a roll kneading method, an inflation extrusion method, a coextrusion method, and a calendar forming method. The plastic working temperature is preferably equal to or higher than the softening point of each component described above, and in consideration of the thermosetting property and moldability of the epoxy resin, for example, 40 to 150 ° C., preferably 50 to 140 ° C., more preferably 70 to 120 ° C. is there.

The thickness of the thermosetting composition 11 is not particularly limited, but is preferably 100 μm or more, more preferably 150 μm or more. The thickness of the thermosetting composition 11 is preferably 2000 μm or less, more preferably 1000 μm or less.

The sealing sheet 1 is used to manufacture a hollow package. Examples of the hollow package include a sensor package, a MEMS (Micro Electro Mechanical Systems) package, a SAW (Surface Acoustic Wave) filter, and the like.

The hollow package includes, for example, a substrate, an electronic device mounted on the substrate, and a protective portion that covers the electronic device. A space is provided between the electronic device and the substrate. Examples of the substrate include a printed wiring board, an LTCC (Low Temperature Co-fired Ceramics) substrate (hereinafter, also referred to as a low-temperature co-fired ceramic substrate), a ceramic substrate, a silicon substrate, and a metal substrate. Examples of electronic devices include sensors, MEMS, SAW chips and the like. The electronic device is preferably a pressure sensor, a vibration sensor, a SAW chip, and more preferably a SAW chip. The protective portion is formed by curing the thermosetting composition 11.

As a method of manufacturing a hollow package using the sealing sheet 1, for example, there is a method of embedding an electronic device in the thermosetting composition 11.

(Manufacturing method of hollow package)
As shown in FIG. 5, the laminated body 31 is arranged between the lower heating plate 41 and the upper heating plate 42. The laminate 31 includes a device mounting body 2, a thermosetting composition 11 arranged on the device mounting body 2, and a separator 12 arranged on the thermosetting composition 11.

The device mount 2 includes a substrate 22 and a SAW chip 23 mounted on the substrate 22. The SAW chip 23 can be obtained by dying a piezoelectric crystal on which a predetermined comb-shaped electrode is formed by a known method to individualize it. The SAW chip 23 can be fixed to the substrate 22 by using a known device such as a flip chip bonder or a die bonder. The SAW chip 23 and the substrate 22 are electrically connected via a protrusion electrode 24 such as a bump. Further, a hollow portion 25 is arranged between the SAW chip 23 and the substrate 22 so as not to hinder the propagation of surface acoustic waves on the surface of the SAW filter. The distance between the SAW chip 23 and the substrate 22 (hereinafter, also referred to as the width of the hollow portion 25) can be appropriately set, and is generally about 10 μm to 100 μm. That is, the device mount 2 includes a substrate 22, a protrusion electrode 24 arranged on the substrate 22, and a SAW chip 23 arranged on the protrusion electrode 24.

As shown in FIG. 6, the laminated body 31 is hot-pressed by the parallel plate method using the lower heating plate 41 and the upper heating plate 42 to form the sealing body 32.

The temperature of the hot press is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 60 ° C. or higher. When the temperature is 40 ° C. or higher, the seal can be firmly sealed. The temperature of the hot press is preferably 150 ° C. or lower, more preferably 90 ° C. or lower, still more preferably 80 ° C. or lower. When the temperature is 150 ° C. or lower, the curing reaction does not proceed excessively before molding by hot pressing, so that the seal can be tightly sealed.

The pressure for hot-pressing the laminate 31 is preferably 0.1 MPa or more, more preferably 0.5 MPa or more, still more preferably 1 MPa or more. The pressure for hot-pressing the laminate 1 is preferably 10 MPa or less, more preferably 8 MPa or less. When it is 10 MPa or less, the SAW chip 23 is not significantly damaged.

The time for hot pressing is preferably 0.3 minutes or longer, more preferably 0.5 minutes or longer. The time for hot pressing is preferably 10 minutes or less, more preferably 5 minutes or less.

The hot press is preferably performed in a reduced pressure atmosphere. By hot pressing in a reduced pressure atmosphere, voids can be reduced and unevenness can be satisfactorily filled. As the depressurizing condition, the pressure is, for example, 0.01 kPa to 5 kPa, preferably 0.1 Pa to 100 Pa.

The sealing body 32 obtained by hot-pressing the laminate 31 includes a substrate 22, a SAW chip 23 mounted on the substrate 22, and a thermosetting composition 11 that covers the SAW chip 23. A separator 12 is arranged on the sealing body 32.

As shown in FIG. 7, the separator 12 is peeled off.

The thermosetting composition 11 is cured by heating the sealing body 32 to form the structure 33.

The heating temperature is preferably 100 ° C. or higher, more preferably 120 ° C. or higher. On the other hand, the upper limit of the heating temperature is preferably 200 ° C. or lower, more preferably 180 ° C. or lower. The heating time is preferably 10 minutes or longer, more preferably 30 minutes or longer. On the other hand, the upper limit of the heating time is preferably 180 minutes or less, more preferably 120 minutes or less. It is preferable to heat the sealing body 32 in a pressurized atmosphere, and the pressure is preferably 0.1 MPa or more, more preferably 0.5 MPa or more. On the other hand, the upper limit is preferably 10 MPa or less, more preferably 5 MPa or less. It is also preferable to heat the sealant 32 under atmospheric pressure.

As shown in FIG. 8, the structure 33 includes a substrate 22, a SAW chip 23 mounted on the substrate 22, and a protective portion 26 that covers the SAW chip 23.

As shown in FIG. 9, the structure 33 is diced to obtain a hollow package 34. The hollow package 34 includes a substrate 22, a SAW chip 23 mounted on the substrate 22, and a protective portion 26 that covers the SAW chip 23. A space is provided between the SAW chip 23 and the substrate 22.

Bumps may be formed on the hollow package 34 and mounted on a separate substrate (not shown). A known device such as a flip tip bonder or a die bonder can be used for mounting the hollow package 34 on the substrate.

As described above, the method for manufacturing a hollow package includes a step of pressurizing the laminated body 31. The laminate 31 comprises a device mount 2 and a thermosetting composition 11 arranged on the device mount 2. The laminate 31 further comprises a separator 12 on which the thermosetting composition 11 is arranged. The device mount 2 includes a substrate 22 and a SAW chip 23 mounted on the substrate 22. The method for producing a hollow package further includes a step of heating the sealed body 32 obtained by the step of pressurizing the laminated body 31. The method for manufacturing the hollow package further includes a step of dividing the structure 33 obtained by the step of heating the sealing body 32 into each SAW chip 23.

(Modification example 1)
As shown in FIG. 10, the sealing sheet 1 of the modified example 1 includes a separator 12, a thermosetting composition 11 arranged on the separator 12, and a separator 13 arranged on the thermosetting composition 11. .. Examples of the separator 13 include a polyethylene terephthalate (PET) film and the like. The separator 13 is preferably one that has undergone a mold release treatment.

(Modification 2)
In the second modification, the thermosetting composition 11 has a multi-layer structure including a plurality of layers.

(Modification example 3)
In the first embodiment, the laminated body 31 is pressed by the parallel plate method, but in the modified example 3, the laminated body 31 is pressed by using a laminator.

Hereinafter, preferred embodiments of the present invention will be described in detail exemplarily. However, the materials, blending amounts, and the like described in this example are not intended to limit the scope of the present invention to those only unless otherwise specified.

[Preparation of thermosetting sheet]
The components used to prepare the thermosetting sheet will be described.
Epoxy resin: YSLV-80XY manufactured by Nippon Steel Chemical Co., Ltd. (bisphenol F type epoxy resin, Epokin equivalent: 200 g / eq., Softening point: 80 ° C.)
Phenol resin: LVR-8210DL manufactured by Gunei Chemical Co., Ltd. (Novolak type phenol resin, hydroxyl group equivalent: 104 g / eq., Softening point: 60 ° C.)
Acrylic polymer: HME-2006M manufactured by Negami Kogyo Co., Ltd. (Carboxyl group-containing acrylic acid ester copolymer, weight average molecular weight: about 600,000, Tg: -35 ° C., acid value: 33 mgKOH / g)
Inorganic filler 1: FB-5SDC (spherical silica, average particle size 5 μm) manufactured by Denki Kagaku Kogyo Co., Ltd.
Inorganic filler 2: SC220G-SMJ manufactured by Admatex (silica with an average particle size of 0.5 μm surface-treated with 3-methacryloxypropyltrimethoxysilane)
Carbon black: # 20 manufactured by Mitsubishi Chemical Corporation
Curing accelerator: 2PHZ-PW (2-phenyl-4,5-dihydroxymethylimidazole) manufactured by Shikoku Chemicals Corporation

According to the compounding ratios shown in Table 1, each component was dissolved and dispersed in methyl ethyl ketone as a solvent to obtain a varnish having a concentration of 90% by weight. This varnish was applied on a silicone release-treated polyethylene terephthalate film having a thickness of 38 μm, and then dried at 110 ° C. for 5 minutes. As a result, a sheet having a thickness of 42 μm was obtained. By laminating 5 sheets of this sheet, a thermosetting sheet having a thickness of 210 μm was obtained.

[Preparation of cured product]
A cured product was obtained by heating and curing a thermosetting sheet at 150 ° C. for 1 hour using a heating oven.

[Preparation of observation sample]
An observation sheet was prepared in the same manner as the thermosetting sheet except that the inorganic filler 1, the inorganic filler 2, and carbon black were not blended. An observation sample was obtained by heating and curing the observation sheet at 150 ° C. for 1 hour using a heating oven.
The reason for creating the observation sample is to observe the sea-island structure. The sea-island structure can be confirmed by observing the cured product, but the sea-island structure can be easily confirmed by observing the observation sample.

[Evaluation]
The following evaluations were performed on the thermosetting sheet, the cured product, and the observation sample. The results are shown in Table 1.

(TEM observation)
The presence or absence of phase separation was confirmed by observing the cut surface of the thermosetting sheet with TEM.

(Tension storage elastic modulus of cured product at 25 ° C)
A strip-shaped test piece having a length of 40 mm, a width of 10 mm, and a thickness of 200 μm was cut out from the cured product with a utility knife. The storage elastic modulus of the test piece was measured at −50 ° C. to 300 ° C. using a solid viscoelasticity measuring device (RSAIII, manufactured by Leometric Scientific Co., Ltd.). The measurement conditions were a frequency of 1 Hz and a heating rate of 10 ° C./min.

(Phase separation of observation sample)
The presence or absence of phase separation was confirmed by observing the cut surface of the observation sample with TEM.

(AFM observation of observation sample)
By observing the cut surface of the observation sample with AFM, it was confirmed which of the thermosetting resin and the acrylic polymer was the main component of the sea phase. Regarding the island phase, it was confirmed which of the thermosetting resin and the acrylic polymer was the main component.

[Evaluation]
The following evaluation was performed using a thermosetting sheet. The results are shown in Table 1.

(Amount of warpage)
As shown in FIG. 11, the alumina substrate 122 (alumina substrate manufactured by Kyocera Corporation, length 102 mm × width 102 mm × thickness 0.2 mm) and the thermosetting sheet 111 (length 102 mm × width 102 mm ×) arranged on the alumina substrate 122. The test laminate 91 having a thickness of 0.21 mm) was heat-pressed at 90 ° C. and 0.2 Pa using an instantaneous vacuum laminate (VS008-1515, manufactured by Mikado Technos). After the heat press, the test laminate 91 was heated at 150 ° C. for 1 hour using a dryer (STH-120 manufactured by ESPEC) to cure the thermosetting sheet 111. After such heating, the test laminate 91 was left at room temperature (25 ° C.) for 1 hour. As shown in FIG. 12, the test laminate 91 was placed on the desk 201, and the distance 301 between the corner of the test laminate 91 and the desk 201 was measured with a ruler.

(Amount of resin infiltrated into the hollow part)
A SAW chip having the following specifications having an aluminum comb-shaped electrode was mounted on a ceramic substrate under the following bonding conditions to prepare a ceramic substrate and a SAW chip mounting substrate having a SAW chip mounted on the ceramic substrate. The gap width between the SAW chip and the ceramic substrate was 20 μm.

<SAW chip>
Chip size: 1.2 mm square (thickness 150 μm)
Bump material: Au (height 20 μm)
Number of bumps: 6 bumps Number of chips: 100 (10 x 10)

<Bonding conditions>
Equipment: Panasonic Electric Works Co., Ltd. Bonding conditions: 200 ° C, 3N, 1sec, ultrasonic output 2W

A laminate was obtained by arranging a thermosetting sheet on the SAW chip mounting substrate. Under the heating and pressurizing conditions shown below, the laminated body was vacuum-pressed by a parallel plate method to obtain a sealed body.

<Vacuum press conditions>
Temperature: 60 ° C
Pressurized pressure: 4 MPa
Vacuum degree: 1.6 kPa
Press time: 1 minute

After opening to atmospheric pressure, the sealed body was heated at 150 ° C. for 1 hour in a hot air dryer to obtain a structure. The interface between the ceramic substrate and the protective portion was cleaved, and the amount of resin penetrated into the hollow portion between the SAW chip and the ceramic substrate was measured with a trade name "Digital Microscope" (200 times) manufactured by KEYENCE. For the resin penetration amount, the maximum reachable distance of the resin penetrated from the end portion of the SAW chip into the hollow portion was measured, and this was taken as the resin penetration amount. When the resin penetration amount was 100 μm or less, it was judged as “◯”. When it exceeded 200 μm, it was judged as “x”.

1 Sealing sheet
2 Device mount 11 Thermosetting composition 12 Separator 13 Separator 22 Substrate 23 SAW chip 24 Protruding electrode 25 Hollow part 26 Protective part 31 Laminated body 32 Encapsulant 33 Structure 34 Hollow package 41 Lower heating plate 42 Upper heating plate

Claims (3)

A sealing sheet used to manufacture a hollow package in which a space is provided between a substrate and an electronic device.
With a thermosetting composition in the form of a sheet,
The thermosetting composition contains an inorganic filler and a residual component.
The content of the inorganic filler in the thermosetting composition is 55% by volume to 85% by volume and 80% by volume or more.
The residual component contains an acrylic polymer and
The content of the acrylic polymer in the residual component is 40% by weight or more, and is
The cured product obtained by curing the thermosetting composition has a sea-island structure including a matrix portion and a domain portion.
The matrix portion contains the acrylic polymer as a main component and contains the acrylic polymer as a main component.
The matrix part is softer than the domain part,
A sealing sheet having a storage elastic modulus of the cured product at 25 ° C. of 5 × 10 ⁷ Pa to 5 × 10 ^{9 Pa.} The residual component further contains a thermosetting resin, and the residual component further contains.
The sealing sheet according to claim 1, wherein the domain portion contains the thermosetting resin as a main component. A step of pressurizing a substrate and a device mount including an electronic device mounted on the substrate, and a laminate having a sheet-like thermosetting composition arranged on the device mount is included.
The thermosetting composition contains an inorganic filler and a residual component.
The content of the inorganic filler in the thermosetting composition is 55% by volume to 85% by volume and 80% by volume or more.
The residual component contains an acrylic polymer and
The content of the acrylic polymer in the residual component is 40% by weight or more, and is
The cured product obtained by curing the thermosetting composition has a sea-island structure including a matrix portion and a domain portion.
The matrix portion contains the acrylic polymer as a main component and contains the acrylic polymer as a main component.
The matrix part is softer than the domain part,
The storage elastic modulus of the cured product at 25 ° C. is 5 × 10 ⁷ Pa to 5 × 10 ^{9 Pa.}
A method for manufacturing a hollow package in which a space is provided between the substrate and the electronic device.

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