JP2016117836A - Heat-conductive sheet, cured article of heat-conductive sheet and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-conductive sheet capable of achieving a semiconductor device excellent in insulation stability under high temperature and high humidity environment, a cured article of the heat-conductive sheet and a semiconductor device excellent in insulation stability under high temperature and high humidity environment.SOLUTION: The heat-conductive sheet contains a thermosetting resin, an inorganic filler dispersed in the thermosetting resin and silicone oil. The silicone oil is preferably modified silicone oil having in a molecular structure, one or more kind selected from an epoxy group, a hydroxyl group, a polyether group, an amino group, a carboxyl group, a carbinol group, an acryl group, a methacryl group, a mercapto group, a fluoroalkyl group, a phenyl group, an aralkyl group, an ester group, an alkyl group having 2 or more carbon atoms, an amide group, a hydrogen group, a carboxylic acid anhydride group, an alkoxy group, a phenol group and a diol group.SELECTED DRAWING: None

Description

  The present invention relates to a heat conductive sheet, a cured product of the heat conductive sheet, and a semiconductor device.

2. Description of the Related Art Conventionally, an inverter device or a power semiconductor device is known in which an insulated gate bipolar transistor (IGBT) and a semiconductor chip such as a diode, a resistor, and an electronic component such as a capacitor are mounted on a substrate.
These power control devices are applied to various devices according to their withstand voltage and current capacity. In particular, from the viewpoint of environmental problems in recent years and the promotion of energy saving, the use of these power control devices for various electric machines is increasing year by year.
In particular, regarding an in-vehicle power control device, it is desired to install the power control device in an engine room together with downsizing and space saving. The engine room has a harsh environment such as a high temperature and a large temperature change, and a member that is more excellent in heat dissipation and insulation at high temperatures is required.

  For example, Patent Document 1 discloses a semiconductor device in which a semiconductor chip is mounted on a support such as a lead frame, and the support and a heat radiating plate connected to a heat sink are bonded with an insulating resin layer.

JP2011-216619A

In a semiconductor device, for example, by providing a heat dissipation member via a heat conductive material formed using a cured product obtained by curing a heat conductive sheet, heat generated inside the device is effectively dissipated to the outside. I am letting. As a result, failures due to characteristic fluctuations in semiconductor elements and the like are suppressed, and the stability of the semiconductor device is improved.
On the other hand, semiconductor devices used for in-vehicle applications and the like are required to have a failure rate under a severe high temperature and high humidity environment at a very low level and to further improve the stability thereof. However, it has been difficult to realize a semiconductor device having sufficient insulation stability, particularly in a high temperature / high humidity environment.

  The present inventor diligently studied the factors that cause the insulation stability of a semiconductor device to deteriorate in a high temperature / high humidity environment. As a result, the insulation stability of the semiconductor device under high-temperature and high-humidity environment is affected by the history of high-temperature and high-humidity. And it discovered newly that it originates in that the thermal radiation efficiency with respect to the Joule heat_generation | fever resulting from the leakage current which arises from the inside of a semiconductor device falls.

  This invention is made | formed in view of the said situation, and provides the heat conductive sheet which can implement | achieve the semiconductor device excellent in the insulation stability in a high temperature and high humidity environment.

According to the present invention,
There is provided a thermally conductive sheet including a thermosetting resin, an inorganic filler dispersed in the thermosetting resin, and silicone oil.

Moreover, according to the present invention,
A cured product of the heat conductive sheet obtained by curing the heat conductive sheet is provided.

Moreover, according to the present invention,
A metal plate,
A semiconductor chip provided on the first surface side of the metal plate;
A heat conductive material joined to a second surface opposite to the first surface of the metal plate;
A sealing resin for sealing the semiconductor chip and the metal plate;
A semiconductor device in which the heat conductive material is formed of the heat conductive sheet is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the heat conductive sheet which can implement | achieve the semiconductor device excellent in the insulation stability in a high temperature / high humidity environment, its hardened | cured material, and the semiconductor device excellent in the insulation stability in a high temperature / high humidity environment are provided. it can.

It is sectional drawing of the semiconductor device which concerns on one Embodiment of this invention. It is sectional drawing of the semiconductor device which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and detailed description thereof is appropriately omitted so as not to overlap. Moreover, the figure is a schematic diagram and does not necessarily match the actual dimensional ratio. Moreover, unless otherwise specified, "~" between the numbers in the sentence represents the following from the above.

  First, the heat conductive sheet which concerns on this embodiment is demonstrated.

The heat conductive sheet which concerns on this embodiment contains a thermosetting resin (A), the inorganic filler (B) disperse | distributed in the thermosetting resin (A), and silicone oil (C).
Here, in this embodiment, a heat conductive sheet says the thing of a B stage state. Moreover, what hardened | cured the heat conductive sheet is called "the hardened | cured material of a heat conductive sheet." In addition, a thermally conductive sheet applied to a semiconductor device and cured is referred to as a “thermal conductive material”. The cured product of the heat conductive sheet includes a heat conductive material. Further, in the present embodiment, the cured product of the heat conductive sheet refers to a C stage state, and is obtained by curing the B stage state heat conductive sheet by, for example, heat treatment at 180 ° C. and 10 MPa for 40 minutes. It is what was done.

The heat conductive sheet is provided, for example, at a bonding interface that requires high heat conductivity in the semiconductor device, and promotes heat conduction from the heat generating element to the heat radiating element. As a result, failures due to characteristic fluctuations in the semiconductor chip or the like are suppressed, and the stability of the semiconductor device is improved.
As an example of the semiconductor device to which the thermally conductive sheet according to the present embodiment is applied, for example, a semiconductor chip is provided on a heat sink (metal plate), and the surface of the heat sink opposite to the surface to which the semiconductor chip is bonded is provided. A structure in which a heat conductive material is provided on the surface is mentioned.
In addition, as another example of the semiconductor device to which the thermally conductive sheet according to the present embodiment is applied, the thermal conductive material, the semiconductor chip bonded to one surface of the thermal conductive material, and the one of the thermal conductive materials. What has a metal member joined to the surface opposite to the surface, and a sealing resin for sealing the heat conductive material, the semiconductor chip, and the metal member.

By using the thermally conductive sheet according to the present embodiment, a semiconductor device having excellent insulation stability under a high temperature and high humidity environment, particularly insulation reliability under application of a DC voltage can be realized. Although this reason is not necessarily clear, the following reasons can be considered.
According to the study of the present inventor, when a semiconductor device using a conventional heat conductive sheet is placed in a severe high temperature / high humidity environment such as in an automobile engine room for a long time, the insulating property of the heat conductive material As a result, it has become clear that the insulation stability of the semiconductor device is lowered. Therefore, the conventional semiconductor device is inferior in insulation stability in a high temperature / high humidity environment.
On the other hand, the semiconductor device using the thermally conductive sheet according to the present embodiment is excellent in insulation stability even in a high temperature / high humidity environment. The reason for this is presumed that the silicone oil (C) in the heat conducting material according to the present embodiment can constrain moisture that has penetrated into the semiconductor device and block the passage of water molecules in the heat conducting material. The
When the passage of water molecules in the heat conducting material is blocked, it is possible to suppress a decrease in insulating properties of the heat conducting material. Therefore, according to the heat conductive sheet concerning this embodiment, a semiconductor device with high insulation stability in a high temperature and high humidity environment is realizable.

The heat conductive sheet according to the present embodiment preferably has a glass transition temperature of 150, which is measured by dynamic viscoelasticity measurement under conditions of a temperature rising rate of 5 ° C./min and a frequency of 1 Hz, of the cured product of the heat conductive sheet. It is more than 160 degreeC, More preferably, it is 160 degreeC or more, More preferably, it is 175 degreeC or more, Most preferably, it is 190 degreeC or more. Although the upper limit of the said glass transition temperature is not specifically limited, For example, it is 300 degrees C or less.
Here, the glass transition temperature of the hardened | cured material of a heat conductive sheet can be measured as follows. First, the heat conductive sheet is heat-treated at 180 ° C. and 10 MPa for 40 minutes to obtain a cured product of the heat conductive sheet. Next, the glass transition temperature (Tg) of the obtained cured product is measured under the conditions of a temperature rising rate of 5 ° C./min and a frequency of 1 Hz by DMA (dynamic viscoelasticity measurement).
When the glass transition temperature is equal to or higher than the above lower limit value, it is possible to further suppress the movement release of the conductive component, and thus it is possible to further suppress the deterioration of the insulating property of the heat conductive sheet due to the temperature rise. As a result, a semiconductor device with even better insulation stability can be realized.
The glass transition temperature can be controlled by appropriately adjusting the type and blending ratio of each component constituting the heat conductive sheet and the method for producing the heat conductive sheet.

  The heat conductive sheet according to the present embodiment is, for example, between a heat generating element such as a semiconductor chip and a substrate such as a lead frame on which the heat generating element is mounted or a wiring board (interposer), or heat dissipation from the substrate and a heat sink. It is provided between the members. Thereby, the heat generated from the heating element can be effectively dissipated to the outside of the semiconductor device while maintaining the insulation of the semiconductor device. For this reason, it becomes possible to improve the insulation stability of a semiconductor device.

  The planar shape of the heat conductive sheet according to the present embodiment is not particularly limited, and can be appropriately selected according to the shape of the heat radiating member, the heating element, and the like, and may be rectangular, for example. The film thickness of the cured product of the heat conductive sheet is preferably 50 μm or more and 250 μm or less. Thereby, the heat | fever from a heat generating body can be more effectively transmitted to a heat radiating member, improving mechanical strength and heat resistance. Furthermore, the balance between heat dissipation and insulation of the heat conducting material is further improved.

  The heat conductive sheet which concerns on this embodiment contains a thermosetting resin (A), the inorganic filler (B) disperse | distributed in the thermosetting resin (A), and silicone oil (C). Hereinafter, each material which comprises the heat conductive sheet which concerns on this embodiment is demonstrated.

(Thermosetting resin (A))
Examples of the thermosetting resin (A) include epoxy resins, cyanate resins, polyimide resins, benzoxazine resins, unsaturated polyester resins, phenol resins, melamine resins, silicone resins, bismaleimide resins, acrylic resins, and the like. As the thermosetting resin (A), one of these may be used alone, or two or more may be used in combination.
As the thermosetting resin (A), an epoxy resin (A1) is preferable. By using the epoxy resin (A1), the glass transition temperature can be increased, and the thermal conductivity of the thermal conductive sheet 140 can be improved.

  Examples of the epoxy resin (A1) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, and bisphenol M type epoxy resin (4,4 ′-(1,3- Phenylenediisopridiene) bisphenol type epoxy resin), bisphenol P type epoxy resin (4,4 '-(1,4-phenylenediisopridiene) bisphenol type epoxy resin), bisphenol Z type epoxy resin (4,4' -Cyclohexidiene bisphenol type epoxy resin), etc .; phenol novolac type epoxy resin, cresol novolac type epoxy resin, tetraphenol group ethane type novolac type epoxy resin, condensed ring aromatic hydrocarbon structure Novolak type epoxy resins such as volac type epoxy resins; epoxy resins having a biphenyl skeleton; arylalkylene type epoxy resins such as xylylene type epoxy resins and epoxy resins having a biphenyl aralkyl skeleton; naphthylene ether type epoxy resins, naphthol type epoxy resins, Naphthalene type epoxy resins, bifunctional or tetrafunctional epoxy type naphthalene resins, binaphthyl type epoxy resins, naphthalene type epoxy resins such as epoxy resins having a naphthalene aralkyl skeleton; anthracene type epoxy resins; phenoxy type epoxy resins; dicyclopentadiene skeletons Epoxy resin having norbornene type epoxy resin; Epoxy resin having adamantane skeleton; Fluorene type epoxy resin; Epoxy having phenol aralkyl skeleton Resins.

Among these, the thermosetting resin (A) has an epoxy resin having a dicyclopentadiene skeleton, an epoxy resin having a biphenyl skeleton, an epoxy resin having an adamantane skeleton, an epoxy resin having a phenol aralkyl skeleton, and a biphenyl aralkyl skeleton. One or more selected from an epoxy resin, an epoxy resin having a naphthalene aralkyl skeleton, a cyanate resin, and the like are preferable.
By using such a thermosetting resin (A), the glass transition temperature of the cured product of the thermally conductive sheet according to the present embodiment is increased, and the heat dissipation and insulation of the thermally conductive sheet and the cured product are increased. Can be improved.

The content of the thermosetting resin (A) contained in the thermally conductive sheet according to the present embodiment is preferably 1% by mass to 30% by mass, and preferably 5% by mass with respect to 100% by mass of the thermally conductive sheet. More preferred is 28% by mass or less. When the content of the thermosetting resin (A) is not less than the above lower limit value, the handling property is improved, and it becomes easy to form a heat conductive sheet.
When the content of the thermosetting resin (A) is not more than the above upper limit, the strength and flame retardancy of the thermally conductive sheet and its cured product are further improved, or the heat of the thermally conductive sheet and its cured product. The conductivity is further improved.

(Inorganic filler (B))
Examples of the inorganic filler (B) include silica, alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide and the like. These may be used alone or in combination of two or more.

  The shape of the inorganic filler (B) is not particularly limited, but is usually spherical.

  The inorganic filler (B) is formed by agglomerating primary particles of scaly boron nitride from the viewpoint of further improving the thermal conductivity of the thermally conductive sheet and the cured product thereof according to this embodiment. The secondary agglomerated particles are preferred.

Secondary agglomerated particles formed by agglomerating the primary particles of flaky boron nitride are prepared by mixing a binder with flaky boron nitride to prepare a slurry, and aggregating it using a spray drying method or the like. It can be formed by firing. The firing temperature is, for example, 1200 to 2500 ° C. The firing time is, for example, 2 to 24 hours.
Thus, when using secondary agglomerated particles obtained by sintering primary particles of flaky boron nitride as the inorganic filler (B), the inorganic filler (B) in the thermosetting resin (A) ) Is particularly preferred as the thermosetting resin (A) is an epoxy resin having a dicyclopentadiene skeleton.

The average particle diameter of the secondary aggregated particles formed by aggregating the flaky boron nitride is, for example, preferably from 5 μm to 180 μm, and more preferably from 10 μm to 100 μm. Thereby, a more excellent thermal conductive sheet can be realized by a balance between thermal conductivity and insulation.
Here, the average particle size of the secondary agglomerated particles is the median diameter (D ₅₀ ) when the particle size distribution of the particles is measured on a volume basis by a laser diffraction particle size distribution measuring device.

The average major axis of the scaly boron nitride primary particles constituting the secondary agglomerated particles is preferably 0.01 μm or more and 20 μm or less, more preferably 0.1 μm or more and 15 μm or less. Thereby, a more excellent thermal conductive sheet and a cured product thereof can be realized by a balance between thermal conductivity and insulation.
The average major axis can be measured by an electron micrograph. For example, the measurement is performed according to the following procedure. First, secondary agglomerated particles are cut with a microtome or the like to prepare a sample. Subsequently, several cross-sectional photographs of the secondary aggregated particles magnified several thousand times are taken with a scanning electron microscope. Next, arbitrary secondary agglomerated particles are selected, and the major axis of the primary particles of scaly boron nitride is measured from the photograph. At this time, the major axis is measured for 10 or more primary particles, and the average value thereof is taken as the average major axis.

The content of the inorganic filler (B) contained in the heat conductive sheet according to the present embodiment is preferably 50% by mass or more and 95% by mass or less with respect to 100% by mass of the heat conductive sheet. More preferably, it is more than mass% and below 88 mass%, and it is especially preferable that they are 60 mass% or more and 80 mass% or less.
By making content of an inorganic filler (B) more than the said lower limit, the thermal conductivity and mechanical strength in a heat conductive sheet and its hardened | cured material can be improved more effectively. On the other hand, by setting the content of the inorganic filler (B) to the upper limit value or less, the film formability and workability of the resin composition are improved, and the film thickness uniformity of the thermally conductive sheet and its cured product is improved. Can be made even better.

The inorganic filler (B) according to the present embodiment is a scale constituting the secondary aggregated particles in addition to the secondary aggregated particles from the viewpoint of further improving the thermal conductivity of the thermal conductive sheet and the cured product thereof. It is preferable that primary particles of scaly boron nitride other than the primary particles of shaped boron nitride are further included. The average major axis of the primary particles of the scaly boron nitride is preferably 0.01 μm or more and 20 μm or less, more preferably 0.1 μm or more and 15 μm or less.
Thereby, a more excellent thermal conductive sheet and a cured product thereof can be realized by a balance between thermal conductivity and insulation.

(Silicone oil (C))
In the present embodiment, the silicone oil (C) is a compound that is oily at room temperature (23 ° C.) among polymer compounds having a siloxane bond as a main skeleton.

In this embodiment, the kinematic viscosity of the silicone oil at 25 ° C. by kinematic viscometer (C) is, fluidity during compacting, from the viewpoint of dispersibility in the resin composition, 50 mm ² / s or more 10,000 mm ² / S or less, more preferably 100 mm ² / s or more and 5,000 mm ² / s or less.

Silicone oil (C) binds moisture that has penetrated into the heat conducting material more effectively, and from the viewpoint of more effectively improving the insulation stability of the resulting semiconductor device, the epoxy group, hydroxyl group in the molecular structure. , Polyether group, amino group, carboxyl group, carbinol group, acrylic group, methacryl group, mercapto group, fluoroalkyl group, phenyl group, aralkyl group, ester group, alkyl group having 2 or more carbon atoms, amide group, hydrogen It is preferably a modified silicone oil having one or more organic groups selected from a group, a carboxylic acid anhydride group, an alkoxy group, a phenol group, and a diol group, an epoxy group, a hydroxyl group, a polyether group, an amino group , Modified silicone oil having one or more organic groups selected from mercapto groups and alkoxy groups More preferably, it is a modified silicone oil having one or more organic groups selected from an epoxy group, an amino group and a polyether group, and is selected from an epoxy group and a polyether group A modified silicone oil having one or more organic groups is more preferred, and a modified silicone oil having a polyether group is particularly preferred.
In the present embodiment, the modified silicone oil refers to one having a linear siloxane skeleton (also referred to as polysiloxane) and having an organic group other than a hydrocarbon group in the molecular structure.
Among the modified silicone oils, those having a dimethyl silicone skeleton in the molecular structure are preferable.

The organic group in the modified silicone oil may be introduced into a part of the side chain of the polysiloxane, may be introduced into one or both ends of the polysiloxane, or added to the side chain of the polysiloxane. And may be introduced at one or both ends.
Here, the modified silicone oil in which an organic group is introduced into a part of the side chain of the polysiloxane is called a side chain modified silicone oil, and the modified silicone oil in which an organic group is introduced into one end of the polysiloxane is a one-end type. Called modified silicone oil, modified silicone oil in which organic groups are introduced at both ends of polysiloxane is called double-ended modified silicone oil, and organic groups are introduced into part of the polysiloxane side chain and both ends of polysiloxane. The modified silicone oil thus obtained is referred to as a side chain double-end modified silicone oil.

In the present embodiment, examples of the silicone oil (C) include straight silicone oils such as dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil; side chain monoamino modified silicone oil, side chain diamino modified silicone oil, Side chain type special amino modified silicone oil, side chain type epoxy modified silicone oil, side chain type alicyclic epoxy modified silicone oil, side chain type carbinol modified silicone oil, side chain type mercapto modified silicone oil, side chain type carboxyl modified Silicone oil, side chain hydrogen modified silicone oil, side chain amino / polyether modified silicone oil, side chain epoxy / polyether modified silicone oil, side chain epoxy / aralkyl modified silicone Side-chain type modified reactive silicone oils such as side oils; side-chain type polyether-modified silicone oils, side-chain type aralkyl-modified silicone oils, side-chain type fluoroalkyl-modified silicone oils, side-chain type long-chain alkyl-modified silicone oils, side-chains Type higher fatty acid ester modified silicone oil, side chain type higher fatty acid amide modified silicone oil, side chain type polyether / long chain alkyl / aralkyl modified silicone oil, side chain type long chain alkyl / aralkyl modified silicone oil, side chain type phenyl modified Side-chain modified non-reactive silicone oil such as silicone oil; double-ended amino-modified silicone oil, double-ended epoxy-modified silicone oil, double-ended alicyclic epoxy-modified silicone oil, double-ended carbinol-modified silicone oil, Double-ended metak -Modified silicone oil, double-ended polyether-modified silicone oil, double-ended mercapto-modified silicone oil, double-ended carboxyl-modified silicone oil, double-ended phenol-modified silicone oil, double-ended silanol-modified silicone oil, double-ended acrylic Both-end type modified reactive silicone oil such as modified silicone oil, both-end type carboxylic acid anhydride-modified silicone oil; Both-end type modified silicone oil such as both-end type polyether-modified silicone oil and both-end type polyether / methoxy-modified silicone oil Non-reactive silicone oil: One-end type epoxy-modified silicone oil, One-end type carbinol-modified silicone oil, One-end-type diol-modified silicone oil, One-end-type methacryl-modified silicone oil, One-end-type carboxyl-modified One-end-type modified reactive silicone oil such as silicone oil; Side-chain both-end-type modified reactive silicone oil such as side-chain amino / both-end methoxy-modified silicone oil, side-chain both-end-type epoxy-modified silicone oil, etc. 1 type, or 2 or more types can be used.
Among these, side chain type amino / polyether modified silicone oil, side chain type epoxy / polyether modified silicone oil, side chain type polyether modified silicone oil, both side chain type epoxy modified silicone oil, side chain type epoxy / aralkyl. One or more selected from modified silicone oils are preferred, and one or more selected from side-chain polyether-modified silicone oils and side-chain amino-polyether-modified silicone oils are more preferred.
As these silicone oils (C), commercially available products can be used. For example, those sold by Shin-Etsu Silicone Co., Ltd. can be used.

  The content of the silicone oil (C) contained in the heat conductive sheet according to this embodiment is a glass of a cured product of the heat conductive sheet while effectively constraining moisture that has penetrated into the heat conductive material. From the viewpoint of further improving the insulation stability of the resulting semiconductor device by further improving the transition temperature, it is preferably 0.2% by mass or more and 10% by mass or less with respect to 100% by mass of the heat conductive sheet. % To 5% by mass is more preferable, and 1.5% to 4.5% by mass is particularly preferable.

(Curing agent (D))
When the epoxy resin (A1) is used as the thermosetting resin (A), the heat conductive sheet according to the present embodiment preferably further includes a curing agent (D).
As a hardening | curing agent (D), 1 or more types selected from a hardening catalyst (D-1) and a phenol type hardening | curing agent (D-2) can be used.
Examples of the curing catalyst (D-1) include organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octylate, cobalt octylate, bisacetylacetonate cobalt (II), and trisacetylacetonate cobalt (III); Tertiary amines such as triethylamine, tributylamine, 1,4-diazabicyclo [2.2.2] octane; 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 2,4-diethylimidazole, Imidazoles such as 2-phenyl-4-methyl-5-hydroxyimidazole and 2-phenyl-4,5-dihydroxymethylimidazole; triphenylphosphine, tri-p-tolylphosphine, tetraphenylphosphonium tetraphenylborate, triphenyl Phosphine To Organic phosphorus compounds such as phenylborane and 1,2-bis- (diphenylphosphino) ethane; phenolic compounds such as phenol, bisphenol A and nonylphenol; organic acids such as acetic acid, benzoic acid, salicylic acid and p-toluenesulfonic acid; etc. Or mixtures thereof. As the curing catalyst (D-1), one kind including these derivatives can be used alone, or two or more kinds including these derivatives can be used in combination.
Although content of the curing catalyst (D-1) contained in the heat conductive sheet which concerns on this embodiment is not specifically limited, 0.001 mass% or more and 1 mass% or less with respect to 100 mass% of heat conductive sheets. Is preferred.

Moreover, as a phenol type hardening | curing agent (D-2), novolak-type phenol resins, such as a phenol novolak resin, a cresol novolak resin, a naphthol novolak resin, an aminotriazine novolak resin, a novolak resin, a trisphenylmethane type phenol novolak resin; Modified phenol resins such as modified phenol resins and dicyclopentadiene modified phenol resins; aralkyl resins such as phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton, and naphthol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton; Examples thereof include bisphenol compounds such as bisphenol F; resol type phenol resins and the like, and these may be used alone or in combination of two or more.
Among these, from the viewpoint of improving the glass transition temperature and reducing the linear expansion coefficient, the phenolic curing agent (D-2) is preferably a novolac type phenol resin or a resol type phenol resin.
Although content of a phenol type hardening | curing agent (D-2) is not specifically limited, 1 mass% or more and 30 mass% or less are preferable with respect to 100 mass% of heat conductive sheets, and 5 mass% or more and 15 mass% or less are more. preferable.

(Coupling agent (E))
Furthermore, the heat conductive sheet which concerns on this embodiment may contain a coupling agent (E).
The coupling agent (E) can improve the wettability of the interface between the thermosetting resin (A) and the inorganic filler (B).

As the coupling agent (E), any of those usually used can be used. Specifically, an epoxy silane coupling agent, a cationic silane coupling agent, an aminosilane coupling agent, a titanate coupling agent, and a silicone oil type. It is preferable to use one or more coupling agents selected from coupling agents.
The addition amount of the coupling agent (E) depends on the specific surface area of the inorganic filler (B) and is not particularly limited, but is 0.1 to 10 parts by mass with respect to 100 parts by mass of the inorganic filler (B). The following is preferable, and 0.5 to 7 parts by mass is particularly preferable.

(Phenoxy resin (F))
Furthermore, the thermally conductive sheet according to the present embodiment may further include a phenoxy resin (F). By including the phenoxy resin (F), the bending resistance of the thermally conductive sheet and its cured product can be further improved.
Moreover, by including a phenoxy resin (F), it becomes possible to reduce the elasticity modulus of a heat conductive sheet and its hardened | cured material, and can improve the stress relaxation force of a heat conductive sheet and its hardened | cured material.
Moreover, when a phenoxy resin (F) is included, fluidity | liquidity will reduce by viscosity increase and it can suppress that a void etc. generate | occur | produce. Moreover, the adhesiveness of a heat conductive sheet and a heat radiating member can be improved. These synergistic effects can further increase the insulation stability of the semiconductor device.

  Examples of the phenoxy resin (F) include a phenoxy resin having a bisphenol skeleton, a phenoxy resin having a naphthalene skeleton, a phenoxy resin having an anthracene skeleton, and a phenoxy resin having a biphenyl skeleton. A phenoxy resin having a structure having a plurality of these skeletons can also be used.

  Content of a phenoxy resin (F) is 3 to 10 mass% with respect to 100 mass% of heat conductive sheets, for example.

(Other ingredients)
The heat conductive sheet according to the present embodiment can contain an antioxidant, a leveling agent, and the like as long as the effects of the present invention are not impaired.

The heat conductive sheet which concerns on this embodiment can be produced as follows, for example.
First, the above-mentioned components are added to a solvent to obtain a varnish-like resin composition. In the present embodiment, for example, a thermosetting resin (A), silicone oil (C), etc. are added to a solvent to produce a resin varnish, and then an inorganic filler (B) is put into the resin varnish to add three A resin composition can be obtained by kneading using a roll or the like. Thereby, an inorganic filler (B) and silicone oil (C) can be more uniformly disperse | distributed in a thermosetting resin (A).
Although it does not specifically limit as said solvent, Methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether, cyclohexanone, etc. are mentioned.

  Subsequently, the said resin composition is shape | molded in a sheet form, and a heat conductive sheet is formed. In the present embodiment, for example, after applying the varnish-like resin composition on a substrate, it is heat-treated and dried to obtain a heat conductive sheet. As a base material, the metal foil which comprises a heat radiating member, a lead frame, a peelable carrier material etc. is mentioned, for example. Moreover, the heat processing for drying a resin composition is performed on the conditions of 80-150 degreeC, 5 minutes-1 hour, for example. The film thickness of the heat conductive sheet is, for example, 60 μm or more and 500 μm or less.

  Next, the semiconductor device according to the present embodiment will be described. FIG. 1 is a cross-sectional view of a semiconductor device 100 according to an embodiment of the present invention.

  In the following, in order to simplify the description, the positional relationship (vertical relationship and the like) of each component of the semiconductor device 100 may be described as the relationship shown in each drawing. However, the positional relationship in this description is independent of the positional relationship when the semiconductor device 100 is used or manufactured.

In this embodiment, an example in which the metal plate is a heat sink will be described. The semiconductor device 100 according to the present embodiment is bonded to the heat sink 130, the semiconductor chip 110 provided on the first surface 131 side of the heat sink 130, and the second surface 132 opposite to the first surface 131 of the heat sink 130. The thermal conductive material 140 and the sealing resin 180 that seals the semiconductor chip 110 and the heat sink 130 are provided.
Details will be described below.

  The semiconductor device 100 includes, for example, a conductive layer 120, a metal layer 150, a lead 160, and a wire (metal wiring) 170 in addition to the above configuration.

  An electrode pattern (not shown) is formed on the upper surface 111 of the semiconductor chip 110, and a conductive pattern (not shown) is formed on the lower surface 112 of the semiconductor chip 110. The lower surface 112 of the semiconductor chip 110 is fixed to the first surface 131 of the heat sink 130 via a conductive layer 120 such as silver paste. The electrode pattern on the upper surface 111 of the semiconductor chip 110 is electrically connected to the electrode 161 of the lead 160 via the wire 170.

  The heat sink 130 is made of metal.

  In addition to the semiconductor chip 110 and the heat sink 130, the sealing resin 180 seals the wires 170, the conductive layer 120, and part of the leads 160 inside. Another part of each lead 160 protrudes from the side surface of the sealing resin 180 to the outside of the sealing resin 180. In the present embodiment, for example, the lower surface 182 of the sealing resin 180 and the second surface 132 of the heat sink 130 are located on the same plane.

  The upper surface 141 of the heat conductive material 140 is attached to the second surface 132 of the heat sink 130 and the lower surface 182 of the sealing resin 180. That is, the sealing resin 180 is in contact with the surface (the upper surface 141) of the heat conducting material 140 on the heat sink 130 side around the heat sink 130.

  The upper surface 151 of the metal layer 150 is fixed to the lower surface 142 of the heat conducting material 140. That is, one surface (upper surface 151) of the metal layer 150 is fixed to a surface (lower surface 142) opposite to the heat sink 130 side of the heat conducting material 140.

  In a plan view, it is preferable that the outline of the upper surface 151 of the metal layer 150 and the outline of the surface (lower surface 142) on the opposite side of the heat conducting material 140 from the heat sink 130 are overlapped.

  Further, the entire surface of the metal layer 150 opposite to the one surface (upper surface 151) (lower surface 152) is exposed from the sealing resin 180. In the case of the present embodiment, as described above, the heat conductive material 140 has the upper surface 141 attached to the second surface 132 of the heat sink 130 and the lower surface 182 of the sealing resin 180, and thus the heat conductive material 140. 140 is exposed to the outside of the sealing resin 180 except for its upper surface 141. The entire metal layer 150 is exposed outside the sealing resin 180.

  In addition, the 2nd surface 132 and the 1st surface 131 of the heat sink 130 are each formed flat, for example.

  Although the mounting floor area of the semiconductor device 100 is not particularly limited, it can be set to 10 × 10 mm or more and 100 × 100 mm or less as an example. Here, the mounting floor area of the semiconductor device 100 is the area of the lower surface 152 of the metal layer 150.

  Further, the number of semiconductor chips 110 mounted on one heat sink 130 is not particularly limited. There may be one or more. For example, it may be 3 or more (6 etc.). That is, as an example, three or more semiconductor chips 110 may be provided on the first surface 131 side of one heat sink 130, and the sealing resin 180 may collectively seal these three or more semiconductor chips 110. .

  The semiconductor device 100 is, for example, a power semiconductor device. The semiconductor device 100 includes, for example, 2 in 1 in which two semiconductor chips 110 are sealed in a sealing resin 180, 6 in 1 in which six semiconductor chips 110 are sealed in a sealing resin 180, or a sealing resin 180. A 7-in-1 configuration in which seven semiconductor chips 110 are sealed can be employed.

  Next, an example of a method for manufacturing the semiconductor device 100 according to the present embodiment will be described.

  First, the heat sink 130 and the semiconductor chip 110 are prepared, and the lower surface 112 of the semiconductor chip 110 is fixed to the first surface 131 of the heat sink 130 via the conductive layer 120 such as silver paste.

  Next, a lead frame (not shown) including the lead 160 is prepared, and the electrode pattern on the upper surface 111 of the semiconductor chip 110 and the electrode 161 of the lead 160 are electrically connected to each other through the wire 170.

  Next, the semiconductor chip 110, the conductive layer 120, the heat sink 130, the wire 170, and a part of the lead 160 are collectively sealed with a sealing resin 180.

Next, the heat conductive material 140 is prepared, and the upper surface 141 of the heat conductive material 140 is attached to the second surface 132 of the heat sink 130 and the lower surface 182 of the sealing resin 180. Furthermore, one surface (upper surface 151) of the metal layer 150 is fixed to a surface (lower surface 142) on the opposite side of the heat conducting material 140 from the heat sink 130 side. Note that the metal layer 150 may be fixed to the lower surface 142 of the heat conductive material 140 in advance before the heat conductive material 140 is attached to the heat sink 130 and the sealing resin 180.
Next, each lead 160 is cut from a frame (not shown) of the lead frame. Thus, the semiconductor device 100 having the structure as shown in FIG. 1 is obtained.

  According to the embodiment as described above, the semiconductor device 100 includes the heat sink 130, the semiconductor chip 110 provided on the first surface 131 side of the heat sink 130, and the second side opposite to the first surface 131 of the heat sink 130. An insulating heat conductive material 140 attached to the surface 132 and a sealing resin 180 sealing the semiconductor chip 110 and the heat sink 130 are provided.

As described above, when the package of the semiconductor device is smaller than a certain level, the larger the area of the package of the semiconductor device, the less the insulation of the heat conductive material becomes a problem. As a result, the electric field at the location where the electric field is most concentrated becomes stronger. For this reason, it is thought that the deterioration of the insulation property by the slight film thickness fluctuation | variation of a heat conductive material may also become apparent as a problem.
On the other hand, the semiconductor device 100 according to the present embodiment includes the heat conductive material 140 having the above structure even when the mounting floor area is a large package having a mounting floor area of 10 × 10 mm or more and 100 × 100 mm or less. Therefore, it can be expected that sufficient durability is obtained.

  Further, in the semiconductor device 100 according to the present embodiment, for example, three or more semiconductor chips 110 are provided on the first surface 131 side of one heat sink 130, and the sealing resin 180 collectively covers these three or more semiconductor chips. Even if the semiconductor device 100 has a sealed structure, that is, even if the semiconductor device 100 is a large package, sufficient durability can be obtained by including the heat conductive material 140 having the above structure. I can expect that.

  Further, when the semiconductor device 100 further includes a metal layer 150 having one surface (upper surface 151) fixed to a surface (lower surface 142) opposite to the heat sink 130 side of the heat conducting material 140, the metal layer 150 is provided. Therefore, the heat dissipation of the semiconductor device 100 is improved.

Further, if the upper surface 151 of the metal layer 150 is smaller than the lower surface 142 of the heat conducting material 140, the lower surface 142 of the heat conducting material 140 is exposed to the outside, and there is a concern that cracks may occur in the heat conducting material 140 due to protrusions such as foreign matters. Occurs. On the other hand, when the upper surface 151 of the metal layer 150 is larger than the lower surface 142 of the heat conducting material 140, the end of the metal layer 150 is in a floating state, and the metal layer 150 is handled in the manufacturing process. May come off.
On the other hand, in a plan view, by forming a structure in which the outer shape line of the upper surface 151 of the metal layer 150 and the outer shape line of the lower surface 142 of the heat conducting material 140 are overlapped, generation of cracks in the heat conducting material 140 and The peeling of the metal layer 150 can be suppressed.

  Further, since the entire surface of the lower surface 152 of the metal layer 150 is exposed from the sealing resin 180, heat can be radiated on the entire surface of the lower surface 152 of the metal layer 150, and high heat dissipation of the semiconductor device 100 can be obtained.

  FIG. 2 is a cross-sectional view of a semiconductor device 100 according to an embodiment of the present invention. The semiconductor device 100 is different from the semiconductor device 100 shown in FIG. 1 in the points described below, and is otherwise configured in the same manner as the semiconductor device 100 shown in FIG.

  In the case of this embodiment, the heat conductive material 140 is sealed in the sealing resin 180. The metal layer 150 is also sealed in the sealing resin 180 except for the lower surface 152 thereof. The lower surface 152 of the metal layer 150 and the lower surface 182 of the sealing resin 180 are located on the same plane.

  FIG. 2 shows an example in which at least two or more semiconductor chips 110 are mounted on the first surface 131 of the heat sink 130. The electrode patterns on the upper surface 111 of the semiconductor chip 110 are electrically connected to each other through a wire 170. For example, a total of six semiconductor chips 110 are mounted on the first surface 131. That is, for example, two semiconductor chips 110 are arranged in three rows in the depth direction of FIG.

  Note that by mounting the semiconductor device 100 shown in FIG. 1 or 2 on a substrate (not shown), a power module including the substrate and the semiconductor device 100 can be obtained.

  It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to these. Moreover, each thickness is represented by the average film thickness.

(Preparation of secondary agglomerated particles composed of primary particles of scaly boron nitride)
A mixture obtained by mixing melamine borate (boric acid: melamine = 2: 1 (molar ratio)) and flaky boron nitride powder (average major axis: 15 μm) (melamine borate: flaky boron nitride powder = 10: 1 (mass ratio)) was added to a 0.2 mass% aqueous solution of ammonium polyacrylate, and mixed for 2 hours to prepare a slurry for spraying (aqueous solution of ammonium polyacrylate: mixture = 100: 30 (mass ratio)). ). Subsequently, this slurry was supplied to a spray granulator and sprayed under the conditions of an atomizer rotation speed of 15000 rpm, a temperature of 200 ° C., and a slurry supply amount of 5 ml / min, thereby producing composite particles. Next, the obtained composite particles were fired under a nitrogen atmosphere at 2000 ° C. for 10 hours to obtain aggregated boron nitride having an average particle size of 80 μm.
Here, the average particle diameter of the aggregated boron nitride was determined by measuring the particle size distribution of the particles on a volume basis with a laser diffraction particle size distribution measuring apparatus (LA-500, manufactured by HORIBA), and the median diameter (D ₅₀ ). .

(Preparation of thermal conductive sheet)
About Examples 1-7 and the comparative example 1, the heat conductive sheet was produced as follows.
First, according to the composition shown in Table 1, a thermosetting resin (A), silicone oil (C), and a curing agent (D) are added to methyl ethyl ketone as a solvent, and this is stirred to form a thermosetting resin composition. A product solution was obtained. Next, the inorganic filler (B) was put into this solution and premixed, and then kneaded with three rolls to obtain a resin composition for a heat conductive sheet in which the inorganic filler was uniformly dispersed. Next, after applying the resin composition for a heat conductive sheet onto a copper foil by using a doctor blade method, this was dried by a heat treatment at 100 ° C. for 30 minutes to form a B-stage having a film thickness of 400 μm. A thermally conductive sheet was produced.
The details of each component in Table 1 are as follows.

(Thermosetting resin (A))
Epoxy resin 1: Epoxy resin having a dicyclopentadiene skeleton (XD-1000, manufactured by Nippon Kayaku Co., Ltd.)
Epoxy resin 2: Epoxy resin having a biphenyl skeleton (YX-4000, manufactured by Mitsubishi Chemical Corporation)
Cyanate resin 1: phenol novolac type cyanate resin (PT-30, manufactured by Lonza Japan)

(Inorganic filler (B))
Filler 1: Agglomerated boron nitride produced by producing secondary agglomerated particles composed of primary particles of flaky boron nitride

(Silicone oil (C))
Silicone oil 1: KF615A (manufactured by Shin-Etsu Chemical Co., Ltd., side chain polyether-modified silicone oil, kinematic viscosity at 25 ° C. by a kinematic viscometer: 920 mm ² / s)
Silicone oil 2: X-22-3939A (manufactured by Shin-Etsu Chemical Co., Ltd., side chain amino / polyether-modified silicone oil, kinematic viscosity at 25 ° C. by dynamic viscometer: 3300 mm ² / s)
Silicone oil 3: X-22-2000 (manufactured by Shin-Etsu Chemical Co., Ltd., side chain type epoxy-modified silicone oil (side chain phenyl type), kinematic viscosity at 25 ° C. by a kinematic viscometer: 190 mm ² / s)

(Curing agent (D))
(Curing catalyst D-1)
Curing catalyst 1: 2-phenyl-4,5-dihydroxymethylimidazole (2PHZ-PW, manufactured by Shikoku Chemicals)
Curing catalyst 2: Triphenylphosphine (Hokuko Chemical Co., Ltd.)
(Phenolic curing agent D-2)
Phenol curing agent 1: Trisphenol methane type phenol resin (MEH-7500, manufactured by Meiwa Kasei Co., Ltd.)

(Measurement of Tg (glass transition temperature))
The glass transition temperature of the cured product of the heat conductive sheet was measured as follows. First, the obtained heat conductive sheet was heat-treated at 180 ° C. and 10 MPa for 40 minutes to obtain a cured product of the heat conductive sheet. Next, the glass transition temperature (Tg) of the obtained cured product was measured by DMA (dynamic viscoelasticity measurement) under conditions of a temperature rising rate of 5 ° C./min and a frequency of 1 Hz.

(Insulation stability evaluation)
For each of Examples 1 to 7 and Comparative Example 1, the insulation stability of the semiconductor package was evaluated as follows. First, the semiconductor package shown in FIG. 1 was manufactured using the hardened | cured material of a heat conductive sheet. Next, the insulation resistance in continuous humidity was evaluated using this semiconductor package under the conditions of a temperature of 85 ° C., a humidity of 85%, and a DC applied voltage of 1.5 kV. A resistance value of 10 ⁶ Ω or less was regarded as a failure. The evaluation criteria are as follows.
◎: No failure for 300 hours or more ◎: Failure for 200 hours to less than 300 hours ○: Failure for 150 hours to less than 200 hours △: Failure for 100 hours to less than 150 hours ×: Failure for less than 100 hours

The semiconductor packages of Examples 1 to 7 using the heat conductive sheet containing silicone oil (C) were excellent in insulation stability in a high temperature / high humidity environment.
The semiconductor package of Comparative Example 1 containing no silicone oil (C) was inferior in insulation stability in a high temperature / high humidity environment.
Therefore, it was found that by using the heat conductive sheet according to the present invention, a semiconductor device having excellent insulation stability under a high temperature and high humidity environment can be obtained.

DESCRIPTION OF SYMBOLS 100 Semiconductor device 110 Semiconductor chip 111 Upper surface 112 Lower surface 120 Conductive layer 130 Heat sink (metal plate)
131 1st surface 132 2nd surface 140 Thermal conductive sheet (thermal conductive material)
141 Upper surface 142 Lower surface 150 Metal layer 151 Upper surface 152 Lower surface 160 Lead 161 Electrode 170 Wire 180 Sealing resin 182 Lower surface

Claims (11)

  A thermally conductive sheet comprising a thermosetting resin, an inorganic filler dispersed in the thermosetting resin, and silicone oil. In the heat conductive sheet according to claim 1,
The silicone oil has an epoxy group, hydroxyl group, polyether group, amino group, carboxyl group, carbinol group, acrylic group, methacryl group, mercapto group, fluoroalkyl group, phenyl group, aralkyl group, ester group in the molecular structure. Thermal conductivity which is a modified silicone oil having one or more organic groups selected from an alkyl group having 2 or more carbon atoms, an amide group, a hydrogen group, a carboxylic acid anhydride group, an alkoxy group, a phenol group and a diol group Sex sheet. In the heat conductive sheet of Claim 1 or 2,
Thermally conductive sheet kinematic viscosity at 25 ° C. of the silicone oil is less than 100 mm ² / s or more 5,000 mm ² / s. In the heat conductive sheet as described in any one of Claims 1 thru | or 3,
The thermosetting resin has an epoxy resin having a dicyclopentadiene skeleton, an epoxy resin having a biphenyl skeleton, an epoxy resin having an adamantane skeleton, an epoxy resin having a phenol aralkyl skeleton, an epoxy resin having a biphenyl aralkyl skeleton, and a naphthalene aralkyl skeleton. The heat conductive sheet which is 1 type, or 2 or more types selected from an epoxy resin and cyanate resin. In the heat conductive sheet as described in any one of Claims 1 thru | or 4,
The said inorganic filler is a heat conductive sheet which is the secondary aggregation particle comprised by the primary particle of scale-like boron nitride. In the heat conductive sheet according to claim 5,
The heat conductive sheet whose average particle diameter of the said secondary aggregation particle is 5 micrometers or more and 180 micrometers or less. In the heat conductive sheet of Claim 5 or 6,
The heat conductive sheet whose average major axis of the primary particle which constitutes the secondary aggregation particle is 0.01 micrometer or more and 20 micrometers or less. In the heat conductive sheet as described in any one of Claims 1 thru | or 7,
The heat conductive sheet whose content of the said inorganic filler is 50 to 95 mass% with respect to 100 mass% of the said heat conductive sheets. In the heat conductive sheet as described in any one of Claims 1 thru | or 8,
The heat conductive sheet whose content of the said silicone oil is 1 to 5 mass% with respect to 100 mass% of the said heat conductive sheets.   The hardened | cured material of the heat conductive sheet formed by hardening | curing the heat conductive sheet as described in any one of Claims 1 thru | or 9. A metal plate,
A semiconductor chip provided on the first surface side of the metal plate;
A heat conductive material joined to a second surface opposite to the first surface of the metal plate;
A sealing resin for sealing the semiconductor chip and the metal plate;
The semiconductor device with which the said heat conductive material was formed with the heat conductive sheet as described in any one of Claims 1 thru | or 9.

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