WO2019212051A1 - Heat conductor and electronic device using same - Google Patents

Abstract

Provided is a heat conductor that has an excellent heat transfer property, that is capable of preventing scattering of fragments, dust, etc., even when cracking occurs therein, and that is capable of being tightly attached to any heat-radiating portions. A heat conductor 1 comprises: a ceramics sheet 2; and resin coating layers 3a, 3b formed on both surfaces of the ceramics sheet 2.

Description

Thermal conductor and electronic device using the same

The present technology relates to a heat conductor disposed between a heating element such as an electronic component and a heat conduction member that diffuses heat of the electronic component, and an electronic apparatus including the heat conductor. This application includes Japanese Patent Application No. 2018-088940 filed on May 2, 2018 in Japan, Japanese Patent Application No. 2018-118471 filed on June 22, 2018 in Japan, Claiming priority based on Japanese Patent Application No. 2019-085828 filed on April 26, 2019 in Japan, and these applications are incorporated herein by reference. The

Various electric devices such as personal computers and smartphones and other electronic devices are becoming smaller, more functional and more complicated, and along with this, the integration density of small electronic components on circuit boards is increasing more and more. . As a result, problems such as failure, functional failure, and shortening of the life due to heat generation of the circuit board and the electronic components mounted on the circuit board become problems.

In order to realize quick heat dissipation of circuit boards and electronic components, the circuit board itself is made of a material with excellent heat dissipation, a heat sink is attached to the circuit board and electronic components, or a sheet-like shape with excellent heat conductivity Measures such as arranging a heat conductor are taken.

JP 2003-092384 A

Conventionally, a graphite sheet has been used as a sheet-like heat conductor used for heat dissipation. Graphite sheets are manufactured from natural graphite or artificial graphite, and because of their crystallinity, they have anisotropy in heat conduction, low thermal conductivity in the thickness direction, are difficult to conduct heat, and are parallel to the surface of the sheet. The thermal conductivity in the surface direction is high and heat is easily transmitted. Further, the graphite sheet has a characteristic that it can be adjusted to an arbitrary thickness of several tens of microns to several thousand microns.

Furthermore, the graphite sheet has a high dielectric constant, shielding properties, and performance as an electromagnetic field shield. Therefore, there is a possibility that an unexpected failure may occur near various communication devices such as communication using high frequency. Due to such properties, the use position of the graphite sheet is limited, and it has been difficult to cope with the case where the shape of the heat radiation portion and the heat conduction member is diversified.

A ceramic sheet is an example of a low dielectric material in the heat conductive material. However, there is a problem that a thin ceramic sheet is cracked when an external force is applied and a critical stress is exceeded. If the ceramic sheet is broken, debris and dust may scatter in the electronic device, which may cause an unexpected failure in the surrounding area.

Therefore, an object of the present technology is to provide a heat conductor that has low dielectric constant and high heat conduction and can be in close contact with any heat radiation portion, and an electronic device using the heat conductor.

In order to solve the above-described problems, a thermal conductor according to the present technology includes a ceramic sheet and a resin coating layer formed on at least one surface of the ceramic sheet.

Also, an electronic device according to the present technology includes an electronic component and a heat conductor that is thermally connected to the electronic component.

According to the present technology, by forming the resin coating layer on at least one surface of the ceramic sheet, the stress applied to the ceramic sheet is relaxed, and the occurrence of cracks can be suppressed. Even when an external force exceeding the limit stress is applied and the ceramic sheet is cracked, it is possible to prevent the ceramic sheet fragments and dust from scattering to the surroundings, thereby preventing an unexpected failure. Moreover, since it is coat | covered with the thin resin coating layer, while being able to maintain a shape, the fall of heat conductivity can be suppressed. Furthermore, the adhesiveness with the site | part installed can be maintained.

FIG. 1A is a cross-sectional view showing an example of an electronic device to which the present technology is applied, and shows an electronic device 10 in which a heat conductor 1 is sandwiched between an electronic component 12 and an external housing 30 as a heat conducting member. It is sectional drawing. FIG. 1B is a cross-sectional view illustrating an example of an electronic device to which the present technology is applied, and is a cross-sectional view illustrating the electronic device 10 having a space between the outer housing 30 and the heat conductor 1. FIG. 1C is a cross-sectional view showing an electronic device 10 having a space between the heat conductor 1 and the electronic component 12. FIG. 1D is a cross-sectional view showing the electronic device 10 in which the heat conductor 1 is sandwiched between the electronic component 12 that is not carried on the substrate 12 and the external housing 30 as a heat conducting member. 2A and 2B are cross-sectional views showing a heat conductor to which the present technology is applied, in which FIG. 2A shows a heat conductor in which a resin coating layer 3 is formed only on one surface of a ceramic sheet 2, and FIG. 2B shows a ceramic sheet. 2 shows a heat conductor in which the resin coating layer 3 is formed on both surfaces, and (C) shows a heat conductor in which the resin coating layers 3 a and 3 b are formed on both surfaces including the end of the ceramic sheet 2. FIG. 3 is a cross-sectional view illustrating an example of the heat conductor 1 in which the resin coating layers 3 a and 3 b are configured by the double-sided adhesive tape 40. FIG. 4 is a cross-sectional view showing a process of disposing the ceramic sheet 2 on the resin composition 21 supported by the PET film 20. FIG. 5 is a cross-sectional view showing a state in which the resin coating layer 3 a is formed on one surface of the ceramic sheet 2. FIG. 6 is a cross-sectional view showing a process of disposing the ceramic sheet 2 having the resin coating layer 3a formed on one surface on the resin composition 21 supported by the PET film. FIG. 7 is a cross-sectional view showing a state in which the resin coating layer 3b is formed on the other surface of the ceramic sheet 2 on which the resin coating layer 3a is formed. FIG. 8 is a cross-sectional view showing the heat conductor 1 in which the ceramic sheet 2 is divided into a plurality of pieces and bendable. In FIG. 9, the electronic component 12 is mounted on both surfaces of the circuit board 11, and the thermoelectric conductor 1 is placed between the electronic component 12 mounted on one surface side of the circuit board 11 and the equipment outer casing 30 that is a heat conducting member. 1 is a cross-sectional view showing an electronic device 10 in which an electronic component 12 sandwiched and mounted on the other surface side of a circuit board 11 is connected to a heat sink 31. FIG.

Hereinafter, a heat conductor to which the present technology is applied and an electronic device using the heat conductor will be described in detail with reference to the drawings. In addition, this technique is not limited only to the following embodiment, Of course, a various change is possible in the range which does not deviate from the summary of this technique. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Heat conductor]
The electronic device 10 using the thermal conductor 1 to which the present technology is applied includes an electronic component 12, a thermal conductor 1 that is thermally connected to the electronic component 12, and the electronic component 12 in contact with the thermal conductor 1. And a heat conducting member 30 that dissipates heat. FIG. 1A is a cross-sectional view illustrating an example of an electronic device 10 that uses an external housing 30 as a heat conducting member. Below, the electronic device 10 and the heat conductor 1 which concern on this technique using the electronic device 10 shown to FIG. 1A are demonstrated.

The electronic device 10 includes a circuit board 11, an electronic component 12 mounted on one surface of the circuit board 11, a thermal conductor 1 thermally connected to the electronic component 12, and an electronic component 12 in contact with the thermal conductor 1. And a device outer casing 30 serving as a heat conducting member for transferring heat generated by the heat sink. The heat conductor 1 is formed in a sheet shape, is disposed between the outer housing 30 and the electronic component 12, and is thermally connected to the outer housing 30 and the electronic component 12. That is, the heat conductor 1 shown in FIG. 1A is used as a so-called heat spreader. 1A, the electronic component 12 and the heat conductor 1 may be connected to each other via the heat conductive sheet 5 or directly without using the heat conductive sheet 5. It may be connected.

FIG. 2 is a cross-sectional view showing a heat conductor 1 to which the present technology is applied. A heat conductor 1 to which the present technology is applied has a ceramic sheet 2 and a resin coating layer 3 formed on at least one surface of the ceramic sheet 2 as shown in FIG. The layer 3 is in contact with the outer casing 30. In particular, as shown in FIG. 2B, in the heat conductor 1, resin coating layers 3a and 3b are formed on both surfaces of the ceramic sheet 2, and one of the resin coating layers 3a and 3b is in contact with the external housing 30. It is preferable. More preferably, in the heat conductor 1, as shown in FIG. 2C, the resin coating layer 3 is formed on both surfaces including the end portion of the ceramic sheet 2, and one of the resin coating layers 3 is an external housing 30. It is preferable to contact with. Below, it demonstrates using the heat conductor 1 by which resin coating layer 3a, 3b was formed in both surfaces of the ceramic sheet 2 shown to FIG. 2 (B).

[Ceramic sheet]
The ceramic sheet 2 is a member having a low dielectric constant, excellent thermal conductivity and serving as a base of the thermal conductor 1, and is not particularly limited as long as it is a material having a high thermal conductivity of 10 W / mK or more. For example, a material having a thermal conductivity of 20 W / mK or higher, such as aluminum nitride, alumina, boron nitride, silicon nitride, or the like as the main component, is preferably used as the main component. Moreover, the ceramic sheet 2 may be comprised by several members, such as what coated the alumina which is an oxide film on the surface of aluminum nitride, for example.

The thickness of the ceramic sheet 2 can be appropriately set according to the space where the heat conductor 1 can be installed. However, the thickness of the electronic device can be reduced, and the thinner the ceramic sheet 2 is, the greater the heat in the thickness direction. Since resistance becomes small, the thinner one is preferable. The thickness of the ceramic sheet 2 is preferably 500 μm or less, for example. In addition, it is preferable that it is 40 micrometers or more from points, such as the handleability of the ceramic sheet 2 and the manufacturing cost of the heat conductor 1.

Further, in general, the ceramic sheet is easily broken as the thickness is reduced, and the broken ceramic sheet impairs the thermal conductivity in the surface direction. However, the thermal conductor 1 to which the present technology is applied is formed by the resin coating layers 3a and 3b. Since the ceramic sheet 2 is coated, shape retention and thermal conductivity can be maintained. This point will be described in detail later.

Further, the shape and size of the ceramic sheet 2 can be appropriately designed according to the shape of the heat dissipating part where the heat conductor 1 is disposed, and can be formed into, for example, a sheet shape or a strip shape. By appropriately giving the ceramic sheet 2 shape anisotropy such as forming the ceramic sheet 2 in a strip shape, the resistance to external force can be improved and cracking can be suppressed.

[Resin coating layer]
The resin coating layers 3a and 3b for coating the ceramic sheet 2 enhance the adhesion between the heat conductor 1 and the external housing 30 and coat at least one surface, preferably both surfaces of the ceramic sheet 2, The stress applied to the ceramic sheet 2 is relieved to suppress the generation of cracks, and even when the ceramic sheet 2 is broken, scattering of debris and dust is prevented. The resin coating layer 3 is not particularly limited as long as it has such an effect, but in view of the function of the adhesive layer made of a stickable material such as an adhesive tape or the function of the heat conductor 1 from the viewpoint of productivity. Thus, it is preferably formed of a heat conductive resin layer made of a resin material used for a conventional heat conductive sheet. Further, in the heat conductor 1, both the resin coating layers 3a and 3b may be constituted by an adhesive layer or a heat conductive resin layer, or one of the resin coating layers 3a and 3b is constituted by an adhesive layer. The other may be constituted by a heat conductive resin layer.

For example, the resin coating layers 3a and 3b are binder resins, and preferably contain components such as a heat conductive filler as necessary. Further, the resin coating layer 3 in contact with the outer casing 30 may be a heat insulating material (for example, a foaming agent or a binder resin containing a foaming agent is used).

[Binder resin]
Examples of the binder resin include a pressure-sensitive adhesive containing an elastomer in addition to a non-sticky resin, and may further be in the form of a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on both sides or one side. As the adhesive tape, a single-sided adhesive tape and a double-sided adhesive tape may be selectively used as necessary. The pressure-sensitive adhesive tape may have a base material such as nonwoven fabric, PET, aluminum foil, or may be baseless. The elastomer is not particularly limited, and polymers such as acrylic, silicone, rubber, and urethane can be used.

For example, acrylic pressure-sensitive adhesive layers include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, vinyl acetate, acrylonitrile, acrylamide, styrene, methyl methacrylate, methyl acrylate, acrylic acid, acrylic A polymer obtained by selecting and copolymerizing monomers such as hydroxyethyl acid and glycidyl methacrylate is optionally added with a tackifier and / or blended with a crosslinking agent and cured.

Moreover, the adhesive tape may be used alone or in combination of two or more. Moreover, the heat conductor 1 can reinforce | strengthen the intensity | strength of the ceramic sheet 2 by comprising the resin coating layers 3a and 3b with the adhesive tape which has a base material.

FIG. 3 is a cross-sectional view showing an example of the heat conductor 1 in which the resin coating layers 3a and 3b are composed of the double-sided adhesive tape 40. In the double-sided pressure-sensitive adhesive tape 40, a pressure-sensitive adhesive layer 42 is formed on both surfaces of a base material 41, and a release film 43 such as a PET film is provided on the surface opposite to the surface supported by the base material 41 of each pressure-sensitive adhesive layer 42. It has been.

3 is formed by sticking one adhesive layer 42 of the double-sided adhesive tape 40 to both surfaces of the ceramic sheet 2. At the time of use, the release film 43 is peeled off from the other pressure-sensitive adhesive layer 42 provided with the release film 43, and connected to the electronic component 12 or the external device housing 30 via the other pressure-sensitive adhesive layer 42.

Also, examples of the binder resin include a thermosetting polymer. Examples of the thermosetting polymer include crosslinked rubber, epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenol resin, unsaturated polyester, diallyl phthalate resin, silicone resin, polyurethane, polyimide silicone, thermosetting polyphenylene. Examples include ether and thermosetting modified polyphenylene ether. These may be used individually by 1 type and may use 2 or more types together.

Examples of the crosslinked rubber include natural rubber, butadiene rubber, isoprene rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene propylene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, butyl rubber, halogenated butyl rubber, fluorine rubber, urethane. Examples thereof include rubber, acrylic rubber, polyisobutylene rubber, and silicone rubber. These may be used individually by 1 type and may use 2 or more types together.

Among these, it is particularly preferable that the thermosetting polymer is a silicone resin from the viewpoints of excellent molding processability and weather resistance, and adhesion and followability to the electronic component 12.

There is no restriction | limiting in particular as a silicone resin, Although it can select suitably according to the objective, It is preferable to contain the main ingredient of a liquid silicone gel, and a hardening | curing agent. Examples of such a silicone resin include an addition reaction type silicone resin, a heat vulcanization type millable type silicone resin using a peroxide for vulcanization, and the like. Among these, addition reaction type silicone resin is particularly preferable because adhesion to the electronic component 12 and the outer casing 30 is required.

As the addition reaction type silicone resin, a two-component addition reaction type silicone resin containing a polyorganosiloxane having a vinyl group as a main ingredient and a polyorganosiloxane having a Si—H group as a curing agent is preferable.

In the combination of the main component of liquid silicone gel and the curing agent, the mixing ratio of the main component and the curing agent is not particularly limited and can be appropriately selected according to the purpose.

The binder resin content is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by volume to 100% by volume, more preferably 15% by volume to 90% by volume, and 20% by volume to 85% by volume is particularly preferred. In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.

[Thermal conductive filler]
The heat conductive filler is not particularly limited as long as it is a low dielectric heat conductive filler, and can be appropriately selected according to the purpose. Examples thereof include inorganic fillers.

The inorganic filler is not particularly limited with respect to its shape, material, average particle diameter and the like, and can be appropriately selected according to the purpose. Examples of the shape of the inorganic filler include a spherical shape, an elliptic spherical shape, a lump shape, a granular shape, a flat shape, and a needle shape. Among these, spherical and elliptical shapes are preferable from the viewpoint of filling properties, and spherical shapes are particularly preferable.

Examples of the inorganic filler include aluminum nitride (aluminum nitride: AlN), aluminum hydroxide, silica, aluminum oxide (alumina), boron nitride, glass, zinc oxide, silicon carbide, and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, aluminum oxide, boron nitride, aluminum nitride, zinc oxide, and silica are preferable, and aluminum oxide, aluminum nitride, and zinc oxide are particularly preferable from the viewpoint of thermal conductivity.

In addition, the inorganic filler may be subjected to a surface treatment. When the inorganic filler is treated with a coupling agent as the surface treatment, the dispersibility of the inorganic filler is improved, and the flexibility of the resin coating layers 3a and 3b is improved.

There is no restriction | limiting in particular as an average particle diameter of an inorganic filler, According to the objective, it can select suitably. When the inorganic filler is alumina, the average particle size is preferably 1 μm to 100 μm, and more preferably 1 μm to 90 μm. If the average particle size is less than 1 μm, the viscosity may increase and mixing may become difficult.

When the inorganic filler is aluminum nitride, the average particle size is preferably 0.3 μm to 100 μm, more preferably 1 μm to 100 μm, and particularly preferably 0.5 μm to 1.5 μm. If the average particle size is less than 0.3 μm, the viscosity increases and mixing may be difficult, and if it exceeds 90 μm, the thickness of the resin coating layer may not be reduced.

The average particle diameter of the inorganic filler can be measured by, for example, a particle size distribution meter or a scanning electron microscope (SEM).

The content of the heat conductive filler is preferably 10% by volume to 85% by volume. When content of a heat conductive filler is less than 10 volume%, there exists a possibility that heat conductivity may become low. Moreover, when it exceeds 85 volume%, the surface property of a resin coating layer will worsen, and there exists a possibility that thermal resistance may increase. In addition, when content of a heat conductive filler exceeds 85 volume%, it will also become difficult to form resin coating layer 3a, 3b.

The heat conductive filler preferably has a relative dielectric constant of 10 or less. In the case where a non-metallic housing is used as the outer housing 30, when the heat conductor 1 is used around the antenna element, the heat conductive filler is preferably a material that does not inhibit electromagnetic waves. If the relative dielectric constant exceeds 10, there is a risk of causing a delay of electromagnetic waves.

Therefore, by using a heat conductive filler having a relative dielectric constant of 10 or less, the heat conductor 1 can transfer the heat of the electronic component 12 to the housing 30 outside the apparatus and is less likely to cause noise. Become.

Examples of the thermally conductive filler having a relative dielectric constant of 10 or less include alumina (relative dielectric constant: 8.5), hexagonal boron nitride (relative dielectric constant: 3.6 to 4.2), and aluminum nitride (relative dielectric constant: 8.5), magnesium oxide (relative permittivity: 9.6), aluminum hydroxide (relative permittivity: 5.1), magnesium hydroxide (relative permittivity: 4.7), and the like.

[Other ingredients]
[Fibrous filler]
There is no restriction | limiting in particular as a fibrous filler, According to the objective, it can select suitably. For example, alumina fiber, aluminum nitride whisker, pitch-based carbon fiber, PAN-based carbon fiber, carbon fiber graphitized from PBO fiber, arc discharge method, laser evaporation method, CVD method (chemical vapor deposition method), CCVD method (catalyst) A carbon fiber synthesized by a chemical vapor deposition method or the like can be used. Among these, alumina fibers, aluminum nitride whiskers, carbon fibers obtained by graphitizing PBO fibers, and pitch-based carbon fibers are particularly preferable from the viewpoint of thermal conductivity. The carbon fiber is preferably coated with an insulating material.

The fibrous filler can be used by subjecting part or all of the surface to a surface treatment, if necessary. Examples of surface treatment include oxidation treatment, nitridation treatment, nitration, sulfonation, or adhesion or bonding of metals, metal compounds, organic compounds, etc. to the surface of functional groups or carbon fibers introduced to the surface by these treatments. And the like. Examples of the functional group include a hydroxyl group, a carboxyl group, a carbonyl group, a nitro group, and an amino group.

The average fiber length (average major axis length) of the fibrous filler is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 5 μm to 10,000 μm.

The average fiber diameter (average minor axis length) of the fibrous filler is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.1 μm to 20 μm.

The content of the fibrous filler is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1% by volume to 70% by volume. If the content is less than 1% by volume, it may be difficult to obtain a sufficiently low thermal resistance, and if it exceeds 70% by volume, the moldability of the resin coating layers 3a and 3b and the orientation of the fibrous filler May affect sex.

The mass ratio (fibrous filler / binder resin) between the fibrous filler and the binder resin is less than 1.30, preferably 0.10 or more and less than 1.30, more preferably 0.30 or more and less than 1.30. 0.50 or more and less than 1.30 is even more preferable, and 0.60 or more and 1.20 or less is particularly preferable. When the mass ratio is 1.30 or more, the flexibility of the resin coating layers 3a and 3b becomes insufficient.

[Other ingredients]
The other components other than the fibrous filler in the resin coating layers 3a and 3b are not particularly limited and may be appropriately selected depending on the intended purpose. For example, thixotropic agents, dispersants, curing accelerators, delays Agents, slight tackifiers, plasticizers, flame retardants, antioxidants, stabilizers, colorants and the like.

For example, it is preferable to mix aluminum hydroxide from the viewpoint of imparting flame retardancy to the heat conductor 1. When aluminum hydroxide is blended as a flame retardant, the average particle size is preferably 15 μm or less, and the smaller the particle size, the more the flame retardancy is improved. It is preferable to treat the surface with silane coupling agent.

There is no restriction | limiting in particular as average thickness of resin coating layer 3a, 3b, Although it can select suitably according to the objective, It is preferable to set it as 3 micrometers or more and 100 micrometers or less. If the thickness of the resin coating layers 3a and 3b is less than 3 μm, it becomes difficult to maintain the shape of the heat conductor 1 when the ceramic sheet 2 is cracked, and the resin coating layers 3a and 3b are also split. There is a possibility that the thermal conductivity in the surface direction is lowered, and fragments and dust of the broken ceramic sheet 2 are scattered around. Moreover, when the thickness of the resin coating layers 3a and 3b is 100 μm or more, there is a possibility that the thermal conductivity of the thermal conductor 1 is lowered.

When the resin coating layers 3a and 3b are formed of a heat conductive resin layer and a fibrous filler is mixed, the resin coating layers 3a and 3b are so coated that the surfaces of the resin coating layers 3a and 3b follow the convex shape of the protruding fibrous filler. It is preferable that the layers are covered with exuded components that have exuded from the layers 3a and 3b. A method of coating the surfaces of the resin coating layers 3a and 3b with the exudation component will be described later.

In addition, the resin coating layers 3a and 3b formed of the heat conductive resin layer have a volume resistance value of 1.V from an applied voltage of 1,000 V in order to prevent a short circuit of an electronic circuit around the electronic component 12 to be used. It is preferably 0 × 10 ¹³ Ω · cm or more, and more preferably 1.0 × 10 ¹⁵ Ω · cm or more. The volume resistance value is measured according to, for example, JIS K-6911.

The resin coating layers 3 a and 3 b formed of the heat conductive resin layer have a compressibility of 3% or more at a load of 0.5 kgf / cm ² from the viewpoint of adhesion to the outer casing 30 and the electronic component 12. It is preferably 15% or more. There is no restriction | limiting in particular as an upper limit of the compression rate of resin coating layer 3a, 3b, Although it can select suitably according to the objective, 30% or less is preferable.

When the resin coating layers 3a and 3b are formed of a heat conductive resin layer and fibrous fillers are mixed, the fibrous fillers are oriented in the thickness direction of the resin coating layers 3a and 3b in the resin coating layers 3a and 3b. May be. By doing so, coupled with the specific mass ratio of the fibrous filler and the binder resin and the specific content of the resin coating layers 3a and 3b described above, while having high thermal conductivity, it also has an insulating property. An excellent heat conductor 1 is obtained.

Here, “the fibrous filler is oriented in the thickness direction of the resin coating layers 3a and 3b” means that 45% or more of the fibrous filler contained in the resin coating layers 3a and 3b is in the thickness direction. It is oriented within the range of 0 ° to 45 °. Note that the fibrous fillers do not necessarily have to be oriented in the same direction. The orientation of the fibrous filler can be measured by, for example, an electron microscope.

[Heat conduction materials and electronic components]
In the heat conductor 1, one of the resin coating layers 3 a and 3 b formed on both surfaces of the ceramic sheet 2 is in contact with the external housing 30. Note that when the resin coating layer 3 is formed on only one surface of the ceramic substrate, the heat conductor 1 may or may not come into contact with the housing 30 outside the device. The external casing 30 is thermally connected to the circuit board 11 and a heating element such as the electronic component 12 mounted on the circuit board 11 via the thermal conductor 1 to promote heat dissipation of the heating element. The material of the external housing 30 is not particularly limited and can be appropriately selected according to the purpose. However, non-metal is good around the antenna, and heat conductivity such as aluminum having high thermal conductivity in other portions. It is preferable to use a metal material having a high thickness. In addition, the heat conductor 1 may be connected with the housing | casing 30 outside an apparatus through the heat conductive sheet 5 suitably.

The electronic component 12 is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include various semiconductor elements such as a CPU, MPU, graphic arithmetic element, antenna element, battery, and the like. In the electronic device illustrated in FIG. 1A, the electronic component 12 is illustrated as a heating element that requires heat dissipation. However, an electronic device to which the present technology is applied can also be applied to the circuit board 11 as a heating element that requires heat dissipation. .

In the heat conductor 1, the resin coating layers 3a and 3b formed of the heat conductive resin layer may have non-adhesiveness. Then, the non-adhesive surface of the heat conductor 1 can be bonded to the electronic component 12 or the heat conductive member 5 using an adhesive. In addition, the heat conductor 1 has at least one of the resin coating layers 3a and 3b to be tacky (slightly tacky) and adheres to the electronic component 12 and the heat conducting member 5 by this adhesive force. Good.

[Effect of thermal conductor]
In such a heat conductor 1, when the resin coating layer 3 is formed on at least one of the ceramic sheets 2, the stress applied to the ceramic sheet 2 is relieved and the occurrence of cracks can be suppressed. Further, even when an external force exceeding the limit stress is applied and the ceramic sheet 2 is cracked, the fragments and dust of the ceramic sheet 2 are prevented from scattering around. Therefore, an unexpected failure of the electronic device can be prevented.

Further, the thermal conductor 1 is coated with the resin coating layer 3 having good thermal conductivity even when the ceramic sheet 2 is cracked by forming the resin coating layer 3 on at least one of the ceramic sheets 2. Therefore, the shape can be maintained and the decrease in thermal conductivity can be suppressed.

Furthermore, the heat conductor 1 can maintain the adhesiveness even if the portion to be installed is not flat by forming the resin coating layer 3 on at least one of the ceramic sheets 2. Even in the case of cracking, the resin coating layer 3 can maintain the adhesion with the electronic component 12 and the external housing 30.

[Covering of ceramic sheet]
Moreover, as for the heat conductor 1, as shown in FIG.2 (C), it is preferable that the ceramic sheet 2 is coat | covered the whole surface including an edge part with the resin coating layer 3. FIG. Thereby, the heat conductor 1 can prevent reliably the fragment of the ceramic sheet 2, and scattering of dust.

A heat conductive sheet 5 may be provided between the heat conductor 1 and the electronic component 12. There is no restriction | limiting in particular in the heat conductive sheet 5, A well-known heat conductive sheet can be used.

[Method for producing heat conductor]
The heat conductor 1 can be formed by laminating a resin composition constituting the resin coating layers 3 a and 3 b made of an adhesive layer or a heat conductive resin layer on the ceramic sheet 2. Alternatively, the heat conductor 1 can be formed by laminating the resin composition constituting the resin coating layers 3a and 3b on the ceramic sheet 2 and appropriately curing the resin composition before or after the lamination. Alternatively, the heat conductor 1 is obtained by supporting the resin composition constituting the resin coating layers 3a and 3b on a support, laminating the ceramic sheet 2, and appropriately curing the resin composition before or after the lamination. Can be formed.

The resin composition constituting the resin coating layers 3a and 3b is an adhesive composition or a heat conductive resin composition, and contains a heat conductive filler and other components as necessary. Examples of the support that supports the resin composition include a PET (polyethylene terephthalate) film. The support may also be present in the resin composition like a double-sided pressure-sensitive adhesive tape. Further, when the support is provided on the outermost surface of the resin coating layers 3a and 3b, the surface that supports the resin composition may be subjected to a peeling treatment.

4 to 7 are cross-sectional views showing an example of the manufacturing process of the heat conductor 1. First, as shown in FIG. 4, a resin composition 21 is applied to the PET film 20 that has been subjected to the peeling treatment. The coating thickness of the resin composition 21 can be appropriately selected according to the purpose, and is 5 μm as an example. One surface of the ceramic sheet 2 is disposed on the resin composition 21 supported by the PET film 20 so that the resin composition 21 spreads over the entire surface of the ceramic sheet 2. The thickness of the ceramic sheet 2 can be appropriately selected according to the purpose in the range of 50 μm to 500 μm, and is 50 μm as an example.

When the resin composition 21 is a pressure-sensitive adhesive composition, it is cured in advance and the ceramic sheet 2 is pasted. Thereby, as shown in FIG. 5, the resin coating layer 3 a supported by the PET film 20 can be formed on one surface of the ceramic sheet 2.

When the resin composition 21 is an uncured thermally conductive resin composition, one surface of the ceramic sheet 2 is disposed on the uncured resin composition 21, and uncured heat conduction is performed on the entire surface of the ceramic sheet 2. The conductive resin composition 21 is spread. Next, as shown in FIG. 5, the heat conductive resin composition 21 is cured by heating the laminate in which the heat conductive resin composition 21 supported by the PET film 20 is laminated on one surface of the ceramic sheet 2. Thus, the resin coating layer 3a is obtained. The heating conditions can be appropriately set according to the composition of the thermally conductive resin composition 21 and the coating thickness, and as an example, the heating condition is 100 ° C. for 30 minutes.

Next, as shown in FIG. 6, the other surface of the ceramic sheet 2 having the resin coating layer 3 a formed on one surface is disposed on the resin composition 21 supported by the PET film 20, and the entire surface is disposed on the other surface of the ceramic sheet 2. The resin composition 21 is spread throughout.

When the resin composition 21 is a pressure-sensitive adhesive composition, it is cured in advance and the ceramic sheet 2 is pasted. Thereby, as shown in FIG. 7, the resin coating layer 3 b supported by the PET film 20 can be formed on the other surface of the ceramic sheet 2.

When the resin composition 21 is an uncured heat conductive resin composition, the laminate having the heat conductive resin composition 21 supported by the PET film 20 on the other surface of the ceramic sheet 2 is heated to heat The conductive resin composition 21 is cured. Thereby, as shown in FIG. 7, the resin coating layer 3b supported by the PET film 20 on the other surface of the ceramic sheet 2 is obtained. The heating conditions can be appropriately set according to the composition of the thermally conductive resin composition 21 and the coating thickness, and as an example, the heating condition is 100 ° C. for 30 minutes.

Thereby, the heat conductor 1 in which the surfaces of the resin coating layers 3a and 3b are coated with the PET film 20 is obtained. At the time of use, the PET film 20 is appropriately peeled from the respective surfaces of the resin coating layers 3a and 3b according to the method of use. When the resin coating layers 3a and 3b are single-sided adhesive tapes, they are used as they are.

In such a heat conductor 1, when fibrous fillers are blended in the resin coating layers 3a and 3b, since the fibrous fillers are randomly oriented, the entanglement between the fibrous fillers increases, so that the fibrous conductors The thermal conductivity is greater than when the filler is oriented in a certain direction. Moreover, since the fibrous fillers are randomly oriented, in addition to the entanglement between the fibrous fillers, the number of contacts with the heat conductive filler (for example, inorganic filler) also increases, so the fibrous filler is oriented in a certain direction. The thermal conductivity is further increased as compared with the case where this is done.

The heat conductor 1 is made to cover the surface of the resin coating layers 3a and 3b formed of the heat conductive resin layer with exuding components that have exuded from the resin coating layers 3a and 3b by pressing, leaving, etc. May be. The “exuding component” refers to a component that is contained in the thermally conductive resin composition but does not contribute to curing, and that does not contribute to the reaction among the non-curable component and the binder resin.

By covering the surfaces of the resin coating layers 3a and 3b with exuded components, the heat conductor 1 can improve the followability and adhesion to the surfaces of the electronic component 12 and the external housing 30 and reduce the thermal resistance. it can. Further, when a fibrous filler is blended in the resin coating layers 3a and 3b, if the coating by the exudation component has a thickness that reflects the shape of the fibrous filler on the surface of the resin coating layers 3a and 3b, An increase in resistance can be avoided.

The press treatment can be performed by using, for example, a pair of press devices including a flat plate and a press head having a flat surface. Moreover, you may perform a press process, heating using the press head which incorporated the heater. Moreover, you may perform a press process using a pinch roll.

Further, the leaving time of the leaving treatment is not particularly limited and can be appropriately selected according to the purpose.

[Division of ceramic sheets]
Moreover, as shown in FIG. 8, the heat conductor 1 may be formed so that the ceramic sheet 2 is divided into a plurality of pieces and bendable. Even when the ceramic sheet 2 is divided into a plurality of parts, the heat conductor 1 can be maintained in shape and at least one surface of the ceramic sheet 2 is covered with the resin coating layers 3a and 3b. A decrease in rate can be suppressed.

Further, since the heat conductor 1 can be bent, the heat conductor 1 can follow the shape of the arrangement surface even when arranged on a non-flat surface, and can maintain the adhesion to the arrangement surface. The heat generated by the electronic component 12 can be efficiently transmitted to the external housing 30 for heat dissipation.

The heat conductor 1 in which the ceramic sheet 2 is divided into a plurality of parts can be formed by applying an external force to the heat conductor 1 formed in a sheet shape and breaking the ceramic sheet 2.

In addition, the heat conductor 1 in which the ceramic sheet 2 is divided into a plurality is provided with a plurality of ceramic sheets 2 arranged adjacent to each other, and a resin coating layer 3 a is continuously formed on one surface of the plurality of ceramic sheets 2. Then, the resin coating layer 3b may be continuously formed on the other surface of the plurality of ceramic sheets 2 continuously. Further, in the heat conductor 1 in which the ceramic sheet 2 is divided into a plurality, the resin coating layer 3 is formed on one surface of the ceramic sheet 2, and after the ceramic sheet 2 is split, the resin coating layer 3 is formed on the other surface. May be provided.

Example embodiment

Hereinafter, embodiments of the heat conductor 1 will be described. Note that the present technology is not limited to the embodiments described below.

[Embodiment 1]
A heat conductive resin composition for forming a resin coating layer is applied on the peeled PET film (application thickness: 5 μm), and a 50 μm thick aluminum nitride ceramics sheet is formed on the heat conductive resin composition film before curing. The heat conductive resin composition spread over the entire surface of the substrate, and then cured in an oven at 100 ° C. for 30 minutes to form a resin coating layer on one surface of the aluminum nitride ceramic sheet. Next, a thermally conductive resin composition for forming a resin coating layer is applied on the peeled PET film (application thickness: 5 μm), and the other surface of the obtained aluminum nitride ceramic sheet with a resin coating layer is placed. After allowing the heat conductive resin composition to spread over the entire surface of the substrate, it was cured in an oven at 100 ° C. for 30 minutes, and a resin coating layer was formed on the other surface of the aluminum nitride ceramic sheet to obtain a heat conductor.

[Embodiment 2]
The aluminum nitride ceramic sheet of the heat conductor obtained in Embodiment 1 was split by applying an external force to obtain a bendable heat conductor.

[Embodiment 3]
A heat conductive resin composition for forming a resin coating layer is applied on the peeled PET film (coating thickness: 5 μm), and a strip-shaped nitridation with a thickness of 50 μm is formed on the heat conductive resin composition film before curing. After placing the aluminum ceramic sheet so that the silicone spreads over the entire surface of the substrate, it was cured in an oven at 100 ° C. for 30 minutes to form a resin coating layer on one surface of the aluminum nitride ceramic sheet. Next, a thermally conductive resin composition for forming a resin coating layer is applied on the peeled PET film (application thickness: 5 μm), and the other surface of the obtained aluminum nitride ceramic sheet with a resin coating layer is placed. After the heat conductive resin composition is spread over the entire surface of the strip-shaped substrate, it is cured in an oven at 100 ° C. for 30 minutes, and a resin coating layer is formed on the other surface of the aluminum nitride ceramic sheet to form a strip-shaped heat conductor. Got. Since the heat conductor according to the third embodiment is formed in a strip shape, it can improve the resistance of the aluminum nitride ceramic sheet to the external force.

[Embodiment 4]
A heat conductive resin composition mixed with aluminum hydroxide to form a resin coating layer is applied on the peeled PET film (coating thickness: 10 μm), and 50 μm on the heat conductive resin composition film before curing. After placing a thick aluminum nitride ceramic sheet so that the thermally conductive resin composition spread over the entire surface of the substrate, it was cured in an oven at 100 ° C. for 30 minutes to form a resin coating layer on one surface of the aluminum nitride ceramic sheet. . Next, a heat conductive resin composition in which aluminum hydroxide is mixed to form a resin coating layer on the peeled PET film is applied (application thickness: 10 μm), and the resulting aluminum nitride ceramic sheet with a resin coating layer is obtained. After placing the other side of the substrate so that the thermally conductive resin composition spreads over the entire surface of the substrate, it was cured in an oven at 100 ° C. for 30 minutes, and a resin coating layer was formed on the other side of the aluminum nitride ceramic sheet to conduct heat conduction. Got the body.

[Embodiment 5]
The aluminum nitride ceramic sheet of the heat conductor obtained in Embodiment 4 was split to obtain a heat conductor that can be bent.

[Embodiment 6]
A heat conductive resin composition mixed with aluminum hydroxide to form a resin coating layer is applied on the peeled PET film (coating thickness: 10 μm), and 50 μm on the heat conductive resin composition film before curing. After placing a thick strip-shaped aluminum nitride ceramic sheet so that the thermally conductive resin composition spreads over the entire surface of the substrate, it is cured in an oven at 100 ° C. for 30 minutes, and a resin coating layer is formed on one surface of the aluminum nitride ceramic sheet. Formed. Next, a heat conductive resin composition in which aluminum hydroxide is mixed to form a resin coating layer on the peeled PET film is applied (application thickness: 10 μm), and the resulting aluminum nitride ceramic sheet with a resin coating layer is obtained. After placing the other side to spread the heat conductive resin composition over the entire surface of the strip substrate, it was cured in an oven at 100 ° C. for 30 minutes to form a resin coating layer on the other side of the aluminum nitride ceramic sheet, A strip-shaped heat conductor was obtained. Since the heat conductor according to the sixth embodiment is formed in a strip shape, the resistance to external force of the aluminum nitride ceramic sheet can be improved.

[Embodiment 7]
A heat conductive resin composition for forming a resin coating layer is applied on the peeled PET film (application thickness: 5 μm), and a 50 μm thick aluminum nitride ceramics sheet is formed on the heat conductive resin composition film before curing. The heat conductive resin composition spread over the entire surface of the substrate, and then cured in an oven at 100 ° C. for 30 minutes to form a resin coating layer on one surface of the aluminum nitride ceramic sheet. Next, a heat conductive resin composition in which aluminum hydroxide is mixed to form a resin coating layer on a PET film that has been subjected to a release treatment is applied (application thickness: 5 μm), and the resulting aluminum nitride ceramic sheet with a resin coating layer is obtained. After placing the other side of the substrate so that the thermally conductive resin composition spreads over the entire surface of the substrate, it was cured in an oven at 100 ° C. for 30 minutes, and a resin coating layer was formed on the other side of the aluminum nitride ceramic sheet to conduct heat conduction. Got the body.

[Embodiment 8]
The aluminum nitride ceramic sheet of the heat conductor obtained in Embodiment 7 was split by applying an external force to obtain a bendable heat conductor.

[Embodiment 9]
A heat conductive resin composition for forming a resin coating layer is applied on the peeled PET film (application thickness: 10 μm), and a strip-shaped nitridation with a thickness of 50 μm is formed on the heat conductive resin composition film before curing. After placing the aluminum ceramic sheet so that the thermally conductive resin composition spread over the entire surface of the substrate, it was cured in an oven at 100 ° C. for 30 minutes to form a resin coating layer on one surface of the aluminum nitride ceramic sheet. Next, a heat conductive resin composition in which aluminum hydroxide is mixed to form a resin coating layer on a PET film that has been subjected to a release treatment is applied (application thickness: 5 μm), and the resulting aluminum nitride ceramic sheet with a resin coating layer is obtained. After placing the other side to spread the heat conductive resin composition over the entire surface of the strip substrate, it was cured in an oven at 100 ° C. for 30 minutes to form a resin coating layer on the other side of the aluminum nitride ceramic sheet, A strip-shaped heat conductor was obtained. Since the heat conductor according to the ninth embodiment is formed in a strip shape, it can improve the resistance of the aluminum nitride ceramic sheet to the external force.

[Embodiment 10]
Double-sided adhesive tape (base material: 12 μm PET film, adhesive layer: 10 μm) is pressed with a hand roller on one side of a 50 μm thick aluminum nitride ceramic sheet, and an acrylic adhesive layer resin coating layer is applied to the aluminum nitride ceramic sheet. Formed. Next, heat is applied by pressing a double-sided adhesive tape (base material: 60 μm PET film, adhesive layer: 10 μm) with a hand roller so as to cover the edge on the other surface of the aluminum nitride ceramic sheet, and cutting the protruding part. A conductor was obtained.

In each of the thermal conductors according to the first to tenth embodiments, since the resin coating layer is formed on both surfaces of the aluminum nitride substrate, the stress applied to the aluminum nitride substrate is relaxed, and the occurrence of cracks is suppressed. Even when the aluminum substrate is cracked or cracked, it is possible to prevent the fragments and dust of the ceramic sheet 2 from scattering to the surroundings. Unexpected failures can be prevented.

In addition, since the thermal conductors according to Embodiments 1 to 10 above all have a resin coating layer having good thermal conductivity on both surfaces of the aluminum nitride substrate, even when the aluminum nitride ceramic sheet is cracked. While maintaining a shape, the fall of thermal conductivity can be suppressed.

Further, any of the thermal conductors according to Embodiments 1 to 10 above can break the aluminum nitride ceramic sheet, or can be bent because the aluminum nitride ceramic sheet is cracked in advance, and the installation site is flat. Even if it is not, adhesiveness can be maintained.

[Variations of electronic devices]
In addition to the embodiment shown in FIG. 1A, the electronic device 10 has electronic components 12 mounted on both surfaces of the circuit board 11 as shown in FIG. 9, and heat is applied between the device outer casing 30 and one electronic component 12. The thermoconductor 1 may be sandwiched together with the conductive sheet 5. In this case, the electronic components 12 mounted on both surfaces of the circuit board 11 may be mounted at positions facing each other, or may be mounted at positions not facing each other as shown in FIG. Further, as shown in FIG. 9, the electronic device 10 is a housing outside the device which is a heat conducting member that dissipates heat from the electronic component 12 and the electronic component 12 on the one surface side of the circuit board 11. The electronic component 12 may be connected to the heat sink 31 via the heat conductive sheet 5 on the other surface side of the circuit board 11.

Further, as shown in FIG. 1B, the electronic device 10 may be provided with a space S between the heat conductor 1 and the device outer casing 30. Also in the configuration illustrated in FIG. 1B, the electronic device 10 can transfer and diffuse the heat generated by the electronic component 12 to the heat conductor 1 through the heat conductive sheet 5 as appropriate. Further, the heat conductor 1 can release heat transferred from the electronic component 12 to the space S.

Moreover, as shown in FIG. 1C, the electronic device 10 may be provided with a space S between the electronic component 12 and the heat conductor 1. Also in the configuration illustrated in FIG. 1C, the electronic device 10 can transfer and diffuse the heat generated by the electronic component 12 to the heat conductor 1 through the space S. Moreover, by providing the space S between the electronic component 12 and the heat conductor 1, it becomes difficult to become a factor that inhibits electromagnetic waves.

In addition, as shown in FIG. 1D, the electronic device 10 does not necessarily have the electronic component 12 supported on the substrate 12. An electronic component 12 such as a battery pack is mounted in the electronic device 10 without being carried on the substrate 12, is in contact with the heat conductor 1, and is thermally connected to the external housing 30 via the heat conductor 1. Connected to. In the configuration shown in FIG. 1D, the heat conductive sheet 5 may be appropriately interposed between the electronic component 12 and the heat conductor 1.

DESCRIPTION OF SYMBOLS 1 Thermal conductor, 2 Ceramic sheet, 3a, 3b Resin coating layer, 5 Thermal conductive member, 10 Electronic device, 11 Circuit board, 12 Electronic component, 20 PET film, 21 Thermal conductive resin composition, 30 External housing 31 heat sink

Claims (19)

1. Ceramic sheets,
   A heat conductor having a resin coating layer formed on at least one surface of the ceramic sheet.
2. The heat conductor according to claim 1, wherein the resin coating layer is formed on both surfaces of the ceramic sheet.
3. The thermal conductor according to claim 1 or 2, wherein the resin coating layer is formed on both surfaces including an end surface of the ceramic sheet.
4. The heat conductor according to claim 1 or 2, wherein the ceramic sheet is divided into a plurality of pieces and is bendable.
5. The heat conductor according to claim 1 or 2, wherein the resin coating layer is formed of an adhesive layer.
6. 6. The thermal conductor according to claim 5, wherein the resin coating layer is formed of an adhesive tape in which the adhesive layer is supported by a support.
7. The heat conductor according to claim 1 or 2, wherein the resin coating layer is formed of a heat conductive resin layer.
8. The heat conductor according to claim 7, wherein the resin coating layer is non-adhesive.
9. The heat conductor according to claim 7, wherein the resin coating layer contains a heat conductive filler.
10. The heat conductor according to claim 9, wherein the heat conductive filler has a dielectric constant of 10 or less.
11. The heat conductor according to claim 1 or 2, wherein the resin coating layer has a thickness of 3 µm to 100 µm.
12. The thermal conductor according to claim 1 or 2, wherein the ceramic sheet has a thickness of 40 µm or more and 500 µm or less.
13. The thermal conductor according to claim 1 or 2, wherein the ceramic sheet is mainly composed of any one of aluminum nitride, alumina, silicon nitride, and boron nitride.
14. Ceramic sheets,
    A resin coating layer formed on at least one surface of the ceramic sheet,
    The resin coating layer is a heat conductor that is a binder resin.
15. The heat conductor according to claim 14, wherein the resin coating layer further contains a heat conductive filler.
16. An electronic device having an electronic component and a heat conductor thermally connected to the electronic component.
17. The thermal conductor is
    Ceramic sheets,
    The electronic device according to claim 16, further comprising a resin coating layer formed on at least one surface of the ceramic sheet.
18. The electronic device according to claim 16 or 17, further comprising a heat conductive member that contacts the heat conductor and dissipates heat of the electronic component.
19. The heat conducting member is an outer casing of an electronic device,
    The electronic device according to claim 18, further comprising a space layer between the heat conductor connected to the electronic component and the housing outside the device.

Images