JP6584752B2 - Resin sheet for sealing - Google Patents

Description

  The present invention relates to a sealing resin sheet.

  In recent years, as the speed of data processing in electronic device devices (for example, semiconductor devices) has increased, the amount of heat generated from electronic devices (for example, semiconductor chips) has increased, and it is important to design electronic device devices that have heat dissipation properties. Sex is increasing. The heat has various adverse effects not only on the electronic device apparatus itself but also on the electronic equipment body in which it is incorporated.

  Thus, conventionally, a thermosetting resin composition containing a heat conductive secondary aggregate obtained by aggregating scaly boron nitride has been proposed (see, for example, Patent Document 1). The secondary aggregate of boron nitride has high thermal conductivity and electrical insulation. Therefore, if it is used for an electronic device apparatus, it can be expected to be an electronic device apparatus having high heat dissipation. Here, the general crystal structure of boron nitride is scaly, and the thermal conductivity in the a-axis direction (plane direction) of the crystal is several times to several times the thermal conductivity in the c-axis direction (thickness direction). The thermal anisotropy is 10 times. Therefore, in Patent Document 1, it is used as a secondary aggregate aggregated so as to require isotropy.

JP 2014-40533 A

  However, when a secondary aggregate of boron nitride is contained in the resin sheet, there is a problem that the sheet becomes hard and brittle due to reasons such as the resin entering the voids in the secondary aggregate, and the followability is poor. Therefore, resin sheets containing secondary aggregates of boron nitride are used only in places where the influence of sheet hardness does not matter, even though they have high thermal conductivity and electrical insulation. I couldn't. For example, Patent Document 1 describes that it can be used to join a power semiconductor element, which is a heat source, and a heat sink. In such a use, there is almost no influence by the hardness of the resin sheet. However, it is considered that the sheet cannot be used as a sealing resin sheet in which the followability of the sheet becomes a problem.

  This invention is made | formed in view of the said problem, The objective is to provide the resin sheet for sealing which has higher thermal conductivity.

  The inventors of the present application have found that the above-mentioned problems can be solved by adopting the following configuration, and have completed the present invention.

That is, the sealing resin sheet according to the present invention is
Including a first filler and a second filler different from the first filler;
The first filler is a secondary aggregate obtained by agglomerating boron nitride crystals having thermal anisotropy having different thermal conductivities depending on directions so as to be isotropic,
The thermal conductivity after thermosetting is 3 W / m · K or more.

According to the above configuration, the first filler and the second filler different from the first filler, and the first filler has boron anisotropy having thermal anisotropy having different thermal conductivity depending on directions. Is a secondary aggregate obtained by agglomerating the crystals so as to have isotropic properties. Therefore, the thermal conductivity of the sealing resin sheet can be increased by the first filler. Further, by including a second filler different from the first filler, it is possible to reduce the increase in viscosity and the increase in elastic modulus of the sheet. That is, since the first filler is a secondary aggregate of boron nitride, it causes a high viscosity and a high elastic modulus of the sheet due to the resin entering the voids in the secondary aggregate. By making it contain with a 2nd filler, content of a 1st filler can be reduced relatively and high viscosity and high elastic modulus can be reduced. Further, by selecting the second filler, functions other than the thermal conductivity (for example, reduction of the linear expansion coefficient, etc.) can be exhibited.
Moreover, since the heat conductivity after thermosetting is 3 W / m · K or more, the heat conductivity is excellent. According to the study by the present inventors, it is extremely difficult to achieve a thermal conductivity of 3 W / m · K or more when boron nitride is not used as a filler.
Thus, according to the said structure, even if it contains boron nitride as a filler, since the high viscosity and high elastic modulus are reduced, the resin sheet for sealing which has higher thermal conductivity than before is provided. can do.

  The said structure WHEREIN: It is preferable that the average particle diameter of a said 1st filler is 1 micrometer or more and 80 micrometers or less.

  In recent years, an electronic device device in which an electronic device is sealed with a sealing resin sheet has been required to be thin. Therefore, when the average particle diameter of the first filler is 1 μm or more and 80 μm or less, it is easy to reduce the thickness of the electronic device device.

  The said structure WHEREIN: It is preferable that the largest particle size of a said 1st filler is 200 micrometers or less.

  When the maximum particle size of the first filler is 200 μm or less, it is easier to reduce the thickness of the electronic device device.

  The said structure WHEREIN: It is preferable that a said 2nd filler is at least one of an alumina and a fused silica.

Alumina (aluminum oxide, Al ₂ O ₃ ) has a relatively high thermal conductivity although it is lower than boron nitride. Further, since the resin does not enter into the alumina particles because it is not an aggregate, the higher the viscosity and the higher the elastic modulus of the sheet are less likely to occur as the secondary aggregate is used. Therefore, if alumina is used as the second filler, thermal conductivity can be maintained while reducing the occurrence of high viscosity and high elastic modulus of the sheet.
In addition, fused silica has a low linear expansion integer and is close to a semiconductor material. Therefore, if fused silica is used as the second filler, warping of the electronic device device can be further suppressed.
If both alumina and fused silica are used, the effects of both can be achieved.

It is sectional drawing which shows typically the resin sheet for sealing which concerns on one Embodiment of this invention. It is a figure which shows typically 1 process of the manufacturing method of the electronic device apparatus which concerns on one Embodiment of this invention. It is a figure which shows typically 1 process of the manufacturing method of the electronic device apparatus which concerns on one Embodiment of this invention. It is a figure which shows typically 1 process of the manufacturing method of the electronic device apparatus which concerns on one Embodiment of this invention. It is a figure which shows typically 1 process of the manufacturing method of the electronic device apparatus which concerns on one Embodiment of this invention. It is a figure which shows typically 1 process of the manufacturing method of the electronic device apparatus which concerns on one Embodiment of this invention.

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

  [Resin sheet for sealing]

  FIG. 1 is a cross-sectional view schematically showing a sealing resin sheet (hereinafter also simply referred to as “resin sheet”) according to an embodiment of the present invention. The resin sheet 11 is typically provided in a state of being laminated on a separator 11a such as a polyethylene terephthalate (PET) film. The separator 11a may be subjected to a mold release process in order to easily peel the resin sheet 11.

The resin sheet 11 has a thermal conductivity after thermosetting of 3 W / m · K or more, preferably 4 W / m · K or more, and more preferably 5 W / m · K or more. Since the thermal conductivity after thermosetting is 3 W / m · K or more, the thermal conductivity is excellent. As a method of setting the thermal conductivity after thermosetting to 3 W / m · K or more, as described later, it can be achieved by containing a first filler.
In the present invention, “thermal conductivity after thermosetting” refers to the thermal conductivity after heating at a pressure of 3 MPa and a temperature of 90 ° C. for 5 minutes and further at 150 ° C. for 30 minutes.

  The resin sheet 11 includes a first filler and a second filler that is different from the first filler.

  The first filler is a secondary aggregate obtained by agglomerating boron nitride crystals having thermal anisotropy having different thermal conductivities depending on directions so as to have isotropic properties.

  The average particle diameter of the first filler is preferably 1 μm or more and 80 μm or less, more preferably 3 μm or more and 70 μm or less. By setting the average particle size of the first filler to 1 μm or more, thermal conductivity can be suitably imparted. On the other hand, when the average particle size of the first filler is 80 μm or less, it is easy to make the electronic device device manufactured using the resin sheet 11 thinner.

The maximum particle size of the first filler is preferably 200 μm or less, and more preferably 180 μm or less. By making the maximum particle size of the first filler 200 μm or less, it is easier to make the electronic device device thinner.
In the present specification, the average particle size and the maximum particle size of the filler are values obtained by measuring with a laser diffraction type particle size distribution measuring device.

  The shape of the first filler, that is, the secondary aggregate is not limited to a spherical shape as long as thermal isotropy is ensured, and may be another shape such as a scale shape. However, when the resin sheet 11 is manufactured, the secondary aggregated particles are spherical in consideration of the fact that the blending amount of the secondary aggregates can be increased while ensuring the fluidity of the thermosetting resin. Is preferred. When the first filler has a shape other than the spherical shape, the average particle size means the length of the long side in the shape.

  The secondary aggregate can be produced according to a known method using a predetermined boron nitride crystal. Specifically, a predetermined boron nitride crystal is fired and crushed, or the predetermined boron nitride crystal is aggregated by a known method such as spray drying and then fired and sintered (grain growth). . Here, the firing temperature is not particularly limited, but is generally 2,000 ° C.

  Moreover, a well-known thing can be used as said secondary aggregate. Specific products include “PT” series (for example, “PTX60”, etc.) manufactured by Momentive Performance Materials Japan GK, and “HP series” (for example, “HP” manufactured by Mizushima Alloy Iron Co., Ltd.). -40 ", etc.), and" Shubi NU UHP "series (for example," Shubi NU UHP-EX ") manufactured by Showa Denko KK can be mentioned.

The second filler is not particularly limited as long as it is different from the first filler. However, the second filler has a certain degree of thermal conductivity, or can impart other functions other than thermal conductivity to the resin sheet 11. Preferably, metal nitrides such as aluminum nitride, silicon nitride, gallium nitride; for example, silicon dioxide, aluminum oxide, magnesium oxide, titanium oxide, zinc oxide, tin oxide, copper oxide, nickel oxide Metal oxides such as aluminum hydroxide, boehmite, magnesium hydroxide, calcium hydroxide, zinc hydroxide, silicic acid, iron hydroxide, copper hydroxide, barium hydroxide, etc .; for example, zirconium oxide water Japanese, tin oxide hydrate, basic magnesium carbonate, hydrotalcite, dowsonite, borax, zinc borate What hydrated metal oxides; silicon carbide, calcium carbonate, barium titanate, and the like potassium titanate. Among these, at least one of alumina and fused silica is preferable.
Alumina (aluminum oxide, Al ₂ O ₃ ) has a relatively high thermal conductivity (36 W / m · K) although it is lower than boron nitride. Further, since the resin does not enter into the alumina particles because it is not an aggregate, the higher the viscosity and the higher the elastic modulus of the sheet are less likely to occur as the secondary aggregate is used. Therefore, if alumina is used as the second filler, thermal conductivity can be maintained while reducing the increase in viscosity and elasticity of the sheet.
Moreover, fused silica has a low linear expansion integer (0.5 × 10 ⁻⁶ / K) and is close to a semiconductor material. Therefore, if fused silica is used as the second filler, warping of the electronic device device can be further suppressed.
If both alumina and fused silica are used, the effects of both can be achieved.

  The average particle diameter of the second filler is not particularly limited, but is, for example, 0.005 μm or more and 80 μm or less. The maximum particle size of the second filler can be set to 200 μm or less, for example. Further, the shape of the second filler is not particularly limited, and may be spherical, for example.

  The content of the first filler is preferably 20% by volume to 80% by volume and more preferably 25% by volume to 75% by volume with respect to the entire resin sheet 11. By setting it as 20 volume% or more, heat conductivity can be provided suitably. Moreover, by setting it as 80 volume% or less, the increase in the viscosity of an extreme sheet | seat and a high elastic modulus can be suppressed.

  The content of the second filler varies depending on the material to be selected, but is preferably 5% by volume or more and 65% by volume or less, and preferably 10% by volume or more and 60% by volume or less based on the entire resin sheet 11. More preferably.

  The total content of the first filler and the second filler is preferably 25% by volume or more and 85% by volume or less, and 30% by volume or more and 80% by volume or less with respect to the entire resin sheet 11. It is more preferable.

  The resin sheet 11 preferably includes a thermosetting resin and a thermoplastic resin.

  As said thermosetting resin, an epoxy resin and a phenol resin are preferable. Thereby, favorable thermosetting is obtained.

  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 an epoxy resin, a phenol novolac type epoxy resin, and a 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, it is preferable that the epoxy equivalent is 150 to 250, and the softening point or the melting point is 50 to 130 ° C., which is solid at room temperature. Of these, triphenylmethane type epoxy resin, cresol novolac type epoxy resin, and biphenyl type epoxy resin are more preferable from the viewpoint of reliability. Further, bisphenol F type epoxy resin is preferable because flexibility can be imparted to the thermosetting resin sheet 11.

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

  As the phenol resin, it is preferable to use a phenol resin having a hydroxyl group equivalent of 70 to 250 and a softening point of 50 to 110 ° C. from the viewpoint of reactivity with the epoxy resin. From the viewpoint of high curing reactivity, a phenol novolac resin can be suitably used. From the viewpoint of reliability, low hygroscopic materials such as phenol aralkyl resins and biphenyl aralkyl resins can also be suitably used.

  From the viewpoint of curing reactivity, the blending ratio of the epoxy resin and the phenol resin is blended so 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 group in the epoxy resin. Preferably, it is 0.9 to 1.2 equivalents.

  The content of the thermosetting resin in 100% by weight of all components other than the filler is preferably 70% by weight or more, more preferably 75% by weight or more, and further preferably 80% by weight or more. CTE1 of hardened | cured material can be made small as it is 70 weight% or more. On the other hand, the content of the thermosetting resin is preferably 95% by weight or less, more preferably 92% by weight or less, still more preferably 90% by weight or less, and particularly preferably 88% by weight or less.

  It is preferable that the resin sheet 11 contains a hardening accelerator.

  The curing accelerator is not particularly limited as long as it cures the epoxy resin and the phenol resin. For example, 2-methylimidazole (trade name; 2MZ), 2-undecylimidazole (trade name; C11). -Z), 2-heptadecylimidazole (trade name; C17Z), 1,2-dimethylimidazole (trade name; 1.2 DMZ), 2-ethyl-4-methylimidazole (trade name; 2E4MZ), 2-phenylimidazole (Trade 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-cyano Tyl-2-undecylimidazole (trade name; C11Z-CN), 1-cyanoethyl-2-phenylimidazolium trimellitate (trade name; 2PZCNS-PW), 2,4-diamino-6- [2'-methyl Imidazolyl- (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-dihydroxyme Examples include imidazole-based curing accelerators such as ruimidazole (trade name; 2PHZ-PW) and 2-phenyl-4-methyl-5-hydroxymethylimidazole (trade name; 2P4MHZ-PW). )).

  Of these, 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole are preferable. Since 2-phenyl-4,5-dihydroxymethylimidazole promotes curing at a high temperature, it can be suppressed from being cured by heat in the embedding process. Moreover, although 2-phenyl-4-methyl-5-hydroxymethylimidazole promotes curing at a relatively low temperature, it is suitable for the case where it is desired to rapidly proceed with thermal curing after the embedding step.

  The content of the curing accelerator is preferably 0.2 parts by weight or more, more preferably 0.5 parts by weight or more, further preferably 0.8 parts by weight or more with respect to 100 parts by weight of the total of the epoxy resin and the phenol resin. It is. The content of the curing accelerator is preferably 5 parts by weight or less, more preferably 2 parts by weight or less with respect to 100 parts by weight of the total of the epoxy resin and the phenol resin.

  The resin sheet 11 preferably contains a thermoplastic resin. Thereby, the heat resistance of the sealing resin sheet obtained, flexibility, and intensity | strength can be improved. The thermoplastic resin is preferably one that can function as an elastomer.

  Examples of the thermoplastic resin include acrylic elastomers, urethane elastomers, silicone lastmers, and polyester elastomers. Of these, acrylic elastomers are preferred from the viewpoints of obtaining flexibility and good dispersibility with the epoxy resin.

  The acrylic elastomer is not particularly limited, and 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. The polymer (acrylic copolymer) etc. which use as a component is mentioned. Examples of the alkyl group include a 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, 2- Examples include an ethylhexyl 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, and a dodecyl group.

  In addition, the other monomer forming the polymer is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Carboxyl group-containing monomers such as acid anhydride monomers such as maleic anhydride or itaconic anhydride, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4- (meth) acrylic acid 4- Hydroxybutyl, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate or (4-hydroxymethylcyclohexyl) -Methyla Hydroxyl group-containing monomers such as relate, styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate or (meth) Examples thereof include sulfonic acid group-containing monomers such as acryloyloxynaphthalene sulfonic acid, and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate. Especially, it is preferable to include at least one of a carboxyl group-containing monomer, a glycidyl group (epoxy group) -containing monomer, and a hydroxyl group-containing monomer from the viewpoint of increasing the viscosity of the resin sheet 11 by reacting with the epoxy resin.

  The thermoplastic resin may have a functional group. As the functional group, a carboxyl group, an epoxy group, a hydroxyl group, an amino group, and a mercapto group are preferable, and a carboxyl group is more preferable.

The weight average molecular weight of the thermoplastic resin is preferably 500,000 or more, more preferably 800,000 or more. On the other hand, the weight average molecular weight of the thermoplastic resin is preferably 2 million or less, more preferably 1.5 million or less. When the weight average molecular weight is within the above numerical range, the viscosity is appropriate, and handling during blending is easy.
The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

  The content of the thermoplastic resin in 100% by weight of all components other than the filler is preferably 5% by weight or more, more preferably 10% by weight or more, still more preferably 11% by weight or more, and still more preferably 12% by weight or more. is there. The softness | flexibility and flexibility of a resin sheet are acquired as it is 5 weight% or more. On the other hand, the content of the thermoplastic resin is preferably 30% by weight or less, more preferably 20% by weight or less. If it is 30% by weight or less, the storage elastic modulus of the resin sheet 11 does not become too high, and both embedding and flow regulation can be achieved.

  The resin sheet 11 may include a flame retardant component as necessary. This can reduce the expansion of combustion when ignition occurs due to component short-circuiting or heat generation. As the flame retardant composition, for example, various metal hydroxides such as aluminum hydroxide, magnesium hydroxide, iron hydroxide, calcium hydroxide, tin hydroxide, complex metal hydroxides; phosphazene flame retardants, etc. should be used. Can do.

  The resin sheet 11 may contain a silane coupling agent. It does not specifically limit as a silane coupling agent, 3-Glycidoxypropyl trimethoxysilane etc. are mentioned.

  The content of the silane coupling agent in the resin sheet 11 is preferably 0.1 to 3% by weight. When it is 0.1% by weight or more, the hardness of the cured resin sheet can be increased and the water absorption rate can be reduced. On the other hand, generation | occurrence | production of outgas can be suppressed as the said content is 3 weight% or less.

  The resin sheet 11 preferably contains a pigment. The pigment is not particularly limited, and examples thereof include carbon black.

  The content of the pigment in the resin sheet 11 is preferably 0.1 to 2% by weight. When the content is 0.1% by weight or more, good marking properties can be obtained. The intensity | strength of the resin sheet after hardening can be ensured as it is 2 weight% or less.

  In addition to the above components, other additives can be appropriately blended in the resin composition as necessary.

[Method for producing sealing resin sheet]
The resin sheet 11 is prepared by dissolving and dispersing a resin or the like for forming the resin sheet 11 in an appropriate solvent to adjust the varnish, and coating the varnish on the separator 11a to a predetermined thickness to form a coating film. Then, the coating film can be formed by drying under predetermined conditions. In addition, it is good also as the resin sheet 11 of desired thickness by laminating | stacking a some resin sheet as needed, and heat-pressing (for example, 60 second at 90 degreeC). It does not specifically limit as a coating method, For example, roll coating, screen coating, gravure coating, etc. are mentioned. As drying conditions, for example, the drying temperature is 70 to 160 ° C. and the drying time is 1 to 30 minutes. Moreover, after apply | coating a varnish on a separator and forming a coating film, the coating film may be dried on the said drying conditions, and the resin sheet 11 may be formed. Then, the resin sheet 11 is bonded together with the separator on the separator 11a. In particular, when the resin sheet 11 contains a thermoplastic resin (acrylic resin), an epoxy resin, and a phenol resin, all of them are dissolved in a solvent, and then applied and dried. Examples of the solvent include methyl ethyl ketone, ethyl acetate, toluene and the like.

  Although the thickness of the resin sheet 11 is not specifically limited, For example, it is 100-2000 micrometers, More preferably, it is 110-1800 micrometers. An electronic device can be favorably sealed as it is in the said range.

  The resin sheet 11 may have a single layer structure or a multilayer structure in which two or more resin sheets having different compositions are laminated, but there is no risk of delamination, and the sheet thickness is highly uniform, A single-layer structure is preferable because it easily reduces moisture absorption.

  The resin sheet 11 includes a SAW (Surface Acoustic Wave) filter; a MEMS (Micro Electro Mechanical Systems) such as a pressure sensor and a vibration sensor; a semiconductor such as an IC such as an LSI, a transistor, and a semiconductor chip; a capacitor; a resistor; an electron such as a CMOS sensor. Used for device sealing. Especially, it can use suitably for sealing of the electronic device (specifically SAW filter, MEMS) which needs hollow sealing, and can use it especially especially especially for sealing of a SAW filter.

[Method of manufacturing hollow package]
FIG. 2A to FIG. 2E are views schematically showing one step of the method for manufacturing the electronic device device according to one embodiment of the present invention.
In the present embodiment, a case where the electronic device device is a hollow package will be described. Specifically, a case where a SAW chip 13 mounted on the printed wiring board 12 is hollow sealed with a resin sheet 11 to manufacture a hollow package will be described. However, the present invention is not limited to this example, and a similar method can be adopted for manufacturing an electronic device device having no hollow portion.

(SAW chip mounting substrate preparation process)
In the method for manufacturing a hollow package according to the present embodiment, first, as shown in FIG. 2A, a laminate 15 in which a plurality of SAW chips 13 are mounted on a printed wiring board 12 is prepared (step A).
The SAW chip 13 corresponds to the electronic device of the present invention. The printed wiring board 12 corresponds to the support body of the present invention.
The SAW chip 13 can be formed by dicing a piezoelectric crystal on which predetermined comb-shaped electrodes are formed by a known method. For mounting the SAW chip 13 on the printed wiring board 12, a known device such as a flip chip bonder or a die bonder can be used. The SAW chip 13 and the printed wiring board 12 are electrically connected via protruding electrodes 13a such as bumps. In addition, a hollow portion 14 is maintained between the SAW chip 13 and the printed wiring board 12 so as not to inhibit the propagation of surface acoustic waves on the surface of the SAW filter. The distance (width of the hollow portion) between the SAW chip 13 and the printed wiring board 12 can be set as appropriate, and is generally about 10 to 100 μm.

(Resin sheet preparation process)
Moreover, in the manufacturing method of the hollow package which concerns on this embodiment, the resin sheet 11 is prepared (process B). As described above, the resin sheet 11 contains secondary aggregates obtained by agglomerating boron nitride crystals having thermal anisotropy having different thermal conductivities depending on directions so as to have isotropic properties.

(Resin sheet placement process)
Next, as shown in FIG. 2B, the laminate 15 is disposed on the lower heating plate 41 with the surface on which the SAW chip 13 is mounted facing upward, and the resin sheet 11 is disposed on the surface of the SAW chip 13. (Process C). In this step, the laminated body 15 may be first arranged on the lower heating plate 41, and then the resin sheet 11 may be arranged on the laminated body 15, and the resin sheet 11 is laminated on the laminated body 15 first. Thereafter, a laminate in which the laminate 15 and the resin sheet 11 are laminated may be disposed on the lower heating plate 41. The separator 11a is preferably not peeled off at this stage.

(Embedding process)
Next, as shown in FIG. 2C, the SAW chip 13 is embedded in the resin sheet 11 by hot pressing with the lower heating plate 41 and the upper heating plate 42 (step D). The embedding process refers to a process from the start of embedding of the SAW chip 13 until the entire SAW chip 13 is embedded.

The hot press conditions for embedding the SAW chip 13 in the resin sheet 11 are preferably such that the SAW chip 13 can be suitably embedded in the resin sheet 11, and the temperature is, for example, 40 to 150 ° C., preferably It is 60-120 degreeC, and a pressure is 0.1-10 Mpa, for example, Preferably it is 0.5-8 Mpa.
In addition, in consideration of improvement in adhesion and followability of the resin sheet 11 to the SAW chip 13 and the printed wiring board 12, it is preferable to press under reduced pressure conditions. As said pressure reduction conditions, it is 0.1-5 kPa, for example, More preferably, it is 0.1-100 Pa.

(Primary thermosetting process)
After the embedding step, the resin sheet 11 is heated to be first thermally cured while maintaining a state in which the laminate 15 and the resin sheet 11 are pressed in a direction in which they are brought closer (step E). Thereby, the sealing body 16 is obtained.
The present inventors, after Step D, that is, after embedding the electronic device in the sealing resin sheet, temporarily heat the sealing resin sheet without applying the pressure to first heat cure. In this case, since the resin sheet 11 is almost not thermally cured, the thickness of the resin sheet 11 deformed so as to be thin due to the pressure at the time of embedding is returned to a slightly thicker direction (spring-backed) It was found that it was cured in the state). And it was guessed that the distance between the secondary aggregates was separated from that at the time of embedding due to this spring back, and this caused the improvement in thermal conductivity.
On the other hand, according to the present embodiment, after the SAW chip 13 is embedded in the resin sheet 11, the resin is maintained while pressing the laminated body 15 and the resin sheet 11 so as to suppress the spring back while maintaining the pressed state. The sheet 11 is heated and subjected to primary thermosetting. Therefore, it is possible to suppress the distance between the secondary aggregates from being buried and improve the thermal conductivity.
In addition, primary thermosetting refers to thermosetting that does not cause springback even if the pressure is released after primary thermosetting, or is less affected by springback, not complete thermosetting. Also good.
The pressurization in the primary thermosetting step may be performed by releasing the pressurization at the time of the embedding step, and then pressurizing again without changing the pressurization at the time of the embedding step. You may perform the pressurization in a thermosetting process.
The conditions of the primary thermosetting step (step E) are those that are 0.8 or more when the thermal conductivity of the resin sheet 11 after thermosetting at a pressure of 3 MPa and a temperature of 150 ° C. for 1 hour is 1. It is preferable that the condition is 0.85 or more.
The condition of thermosetting for 1 hour at a pressure of 3 MPa and a temperature of 150 ° C. is a condition assuming a case where the sealing resin sheet is completely thermoset under pressure conditions that do not cause springback.
If the condition of the step E is 0.8 or more when the thermal conductivity of the resin sheet 11 after thermosetting at a pressure of 3 MPa and a temperature of 150 ° C. for 1 hour is 1, the springback is performed. Even so, the thermal conductivity can be 0.8 or more compared to the case where no springback occurs. Therefore, it is possible to improve the thermal conductivity more suitably.
Specific numerical values of the conditions in the step E can be set as appropriate according to the constituent material of the resin sheet 11, but the pressure conditions are preferably 0.01 to 20 MPa, more preferably 0.05 to 18 MPa, for example. . Moreover, as temperature conditions of the said process E, 50-200 degreeC is preferable, for example, and 60-180 degreeC is more preferable. In addition, the thermosetting time in the step E is preferably, for example, 10 seconds to 3 hours, and more preferably 20 seconds to 2 hours.

(Secondary heat curing process)
Next, the separator 11a is peeled off, and the resin sheet 11 is subjected to secondary thermosetting (see FIG. 2D). The conditions for the secondary thermosetting treatment can be appropriately set according to the conditions for the primary thermosetting treatment and the constituent materials of the resin sheet 11, but for example, the heating temperature is preferably 100 ° C or higher, more preferably 120 ° C. That's it. 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 more, more preferably 30 minutes or more. On the other hand, the upper limit of the heating time is preferably 180 minutes or less, more preferably 120 minutes or less. Moreover, you may pressurize as needed, Preferably it is 0.1 Mpa or more, More preferably, it is 0.5 Mpa or more. On the other hand, the upper limit is preferably 10 MPa or less, more preferably 5 MPa or less.
In the primary thermosetting step, when the resin sheet 11 is completely thermoset, the secondary thermosetting treatment step may not be performed. Moreover, the timing which peels the separator 11a is not limited after primary thermosetting and before secondary thermosetting.

(Dicing process)
Subsequently, the sealing body 16 may be diced (see FIG. 2E). Thereby, the hollow package 18 in the SAW chip 13 unit can be obtained.

(Board mounting process)
If necessary, a substrate mounting process can be performed in which rewiring and bumps are formed on the hollow package 18 and mounted on a separate substrate (not shown). For mounting the hollow package 18 on the substrate, a known device such as a flip chip bonder or a die bonder can be used.

  In the embodiment described above, the case where the support of the present invention is the printed wiring board 12 has been described. However, the support of the present invention is not limited to this example, and may be a ceramic substrate, a silicon substrate, a metal substrate, or the like. May be.

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

The components used in Examples and Comparative Examples 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: LVR8210DL (Novolak type phenol resin, hydroxyl equivalent: 104 g / eq., Softening point: 60 ° C.) manufactured by Gunei Chemical Co., Ltd.
Thermoplastic resin: ME-2000M manufactured by Negami Kogyo Co., Ltd. (carboxyl group-containing acrylic ester polymer, weight average molecular weight: about 600,000, Tg: -35 ° C., acid value: 20 mgKOH / g)
Carbon black: # 20 manufactured by Mitsubishi Chemical
Filler 1: Secondary aggregate of boron nitride (manufactured by Mizushima Alloy Iron Company, product name: HP-40 (average particle size: 40 μm, maximum particle size: 180 μm))
Filler 2: Alumina (manufactured by Admatechs, product name: AE-9104SME (average particle size: 3 μm, maximum particle size: 10 μm))
Filler 3: FB-5SDC manufactured by Denki Kagaku Kogyo Co., Ltd. (spherical fused silica, average particle size 5 μm, maximum particle size: 20 μm)
Curing accelerator 1: 2PHZ-PW (2-phenyl-4,5-dihydroxymethylimidazole) manufactured by Shikoku Kasei Kogyo Co., Ltd.
Curing accelerator 2: 2P4MHZ-PW (2-phenyl-4-methyl-5-hydroxymethylimidazole) manufactured by Shikoku Kasei Kogyo Co., Ltd.

[Production of sealing resin sheet]
According to the blending ratio 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. The varnish was applied on a release treatment film made of a polyethylene terephthalate film having a thickness of 38 μm after the release treatment of silicone, and then dried at 110 ° C. for 3 minutes. This sheet was laminated to obtain a thermosetting resin sheet having a thickness of 220 μm.

(Measurement of thermal conductivity after thermosetting)
First, the sealing resin sheets of Examples and Comparative Examples were heated while being pressed by a parallel plate method, and were thermally cured. At this time, after heating at a pressure of 3 MPa and a temperature of 90 ° C. for 5 minutes, heating was performed at 150 ° C. for 30 minutes.
Next, the thermal conductivity of these sealing resin sheets after thermosetting was measured. The thermal conductivity was obtained from the following formula. The results are shown in Table 1.
(Thermal conductivity) = (thermal diffusion coefficient) x (specific heat) x (specific gravity)

<Thermal diffusion coefficient>.
After producing the sealing resin sheet, it was heated at a pressure of 3 MPa and a temperature of 90 ° C. for 5 minutes, and then heated at 150 ° C. for 30 minutes. Using this sample, the thermal diffusion coefficient was measured using a xenon flash method calorimeter (manufactured by Netch Japan Co., Ltd., LFA447 nanoflash).

<Specific heat>
It calculated | required by the measuring method according to the specification of JIS-7123 using DSC (The product made from TA instrument, Q-2000).

<Specific gravity>
Measurement was performed by the Archimedes method using an electronic balance (manufactured by Shimadzu Corporation, AEL-200).

(Sealability evaluation)
A SAW chip having the following specifications on which an aluminum comb-shaped electrode was formed was mounted on a ceramic substrate under the following bonding conditions to produce a SAW chip mounting substrate including the ceramic substrate and the 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: manufactured by Panasonic Electric Works Co., Ltd. Bonding conditions: 200 ° C., 3N, 1 sec, ultrasonic output 2W

A sealing resin sheet was disposed on the SAW chip mounting substrate.
Next, under the conditions shown below, the SAW chip was embedded in the sealing resin sheet by vacuum pressing using a parallel plate method.

<Vacuum press conditions>
Temperature: 60 ° C
Applied pressure: 4 MPa
Degree of vacuum: 1.6 kPa
Press time: 1 minute

  After opening to atmospheric pressure, a primary thermosetting treatment was further performed under the following conditions.

<First thermosetting treatment conditions>
Temperature: 90 ° C
Applied pressure: 3 MPa
Press time: 5 minutes

  The obtained sealing body was peeled off at the interface between the substrate and the sealing resin (sealing resin sheet) to expose the element surface of the SAW chip. Then, it observed with the optical microscope. The sealing resin sheet has good followability with respect to the SAW chip, and the case where the SAW chip is sealed without a void between the SAW chip and the sealing resin sheet is indicated as “◯”. The case where the followability of the resin sheet was poor and the SAW chip was sealed with a void between the SAW chip and the sealing resin sheet was evaluated as “x”. The results are shown in Table 1.

11 Resin sheet for hollow sealing 11a Support 13 SAW chip 16 Sealing body 18 Hollow package

Claims (3)

A second filler different from the first filler and the first filler and a thermoplastic resin;
The first filler is a secondary aggregate obtained by agglomerating boron nitride crystals having thermal anisotropy having different thermal conductivities depending on directions so as to be isotropic,
Der thermal conductivity of 3W / m · K or more after heat curing is,
The second filler, alumina and at least one encapsulating resin sheet, characterized in der Rukoto of fused silica.   2. The sealing resin sheet according to claim 1, wherein an average particle diameter of the first filler is 1 μm or more and 80 μm or less.   The sealing resin sheet according to claim 1, wherein the first filler has a maximum particle size of 200 μm or less.

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