JP2014009343A - Resin sheet and production method of the same, resin sheet cured product, and heat radiation component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin sheet that exerts excellent thermal conductivity, a production method of the same and a heat radiation component using the same.SOLUTION: A resin sheet is produced by a production method that includes the steps of: imparting a filler to at least one surface of a first composite sheet containing a first curable component and a first filler to form a filler layer; laminating a second composite sheet containing a second curable component and a second filler on the filler layer to obtain a laminate; and bringing the first composite sheet and the second composite sheet into contact with each other, and embedding the filler layer in at least one chosen from the first composite sheet and the second composite sheet to obtain a resin sheet. Moreover, a heat radiation component includes a metallic workpiece and the resin sheet disposed to contact with the metallic workpiece.

Description

  The present invention relates to a resin sheet and a method for producing the same, a cured resin sheet, and a heat dissipation member.

  In the field of semiconductors such as power transistors, thermistors, printed wiring boards and IC chips, and other fields of electrical and electronic components, epoxy resins and inorganic fillers are included as thermally conductive insulating materials constituting the heat dissipation member. Thermally conductive resin compositions are widely used.

  The thermal conductive resin sheet is required to have excellent thermal conductivity. Therefore, in many cases, a method of adding an inorganic filler having a high thermal conductivity to the thermally conductive resin sheet at a high filling rate is used.

  For example, Patent Document 1 discloses a heat conductive resin composition in which boron nitride filler is filled in an epoxy resin at a high filling rate of 55 volume% to 60 volume%, and 4.4 W / mK to 6. It is said that a molded product having a thermal conductivity of 9 W / mK can be obtained.

JP 2008-179720 A

  As a conventional method for filling an inorganic filler, a method of simply mixing a resin component and a filler is common. For example, in Patent Document 1, a slurry containing an epoxy resin and a boron nitride filler is kneaded with a mixer. Such a method is considered to have two problems. The first problem is that it is very difficult to achieve a higher filler filling rate. For example, when the above method is employed using alumina or boron nitride, the filling to about 70% by volume becomes the limit. If the filler filling rate is further increased, coating becomes difficult and moldability as a resin sheet tends to be lowered.

  The second problem is that when the resin component and the filler are kneaded, the surface of the filler is gradually covered with the resin, and thus it may be difficult to obtain sufficient thermal conductivity. This is presumably because when the surface of the filler is coated with a resin, the filler and the filler are difficult to approach each other, that is, the distance between the fillers is increased, and sufficient thermal conductivity cannot be obtained. For example, in Patent Document 1, although an inorganic filler is filled at a high filling rate of 55% to 60% by volume, only a molded product having a thermal conductivity of 4.4 W / mK to 6.9 W / mK is obtained. Absent.

  As described above, it is difficult to solve the two problems by the method of kneading resin and filler, and there is a limit to greatly improving the thermal conductivity. Thus, in the field of heat dissipation materials that require higher thermal conductivity, the current situation is that the demand has not been fully met.

  Therefore, the subject of this invention is providing the resin sheet which solves the said subject, and expresses the outstanding heat conductivity, its manufacturing method, and a heat radiating member using the same.

  As a result of diligent investigation to solve the above problems, it is possible to bring the filler close to the filler and to infiltrate the molten resin into the gap between the fillers by devising the manufacturing process. I found out that Thereby, it came to implement | achieve the resin sheet which expresses higher thermal conductivity, its manufacturing method, and a heat radiating member using the same. That is, specific means for solving the above problems are as follows.

<1> A step of forming a filler layer by applying a filler on at least one surface of a first composite sheet containing a curable component and a filler, and a step of containing a curable component and a filler on the filler layer. Laminating two composite sheets to obtain a laminate, bringing the first composite sheet and the second composite sheet into contact with each other, and forming the filler layer into the first composite sheet and the second composite sheet. And a step of embedding in at least one selected from the above to obtain a resin sheet.

<2> The process of obtaining the said resin sheet is a manufacturing method of the resin sheet as described in said <1> including a press process.

<3> The method for producing a resin sheet according to <1> or <2>, wherein the curing components of the first composite sheet and the second composite sheet independently include an epoxy resin and a curing agent.

<4> The resin sheet is a method for producing a resin sheet according to any one of the items <1> to <3>, in which a filler content is 75% by volume or more in a total solid content volume.

<5> A resin sheet obtained by the production method according to any one of <1> to <4>.

<6> A cured resin sheet that is a cured product of the resin sheet according to <5>.

<7> A cured resin sheet obtained by removing a part of the cured product from at least one surface of the cured product of the resin sheet according to <5>.

<8> A heat dissipating member comprising a metal workpiece and the resin sheet according to <5>.

<9> A heat dissipation member comprising a metal workpiece and the cured resin sheet according to <6> or <7>.

<10> A resin sheet comprising a curable component and a filler, wherein the content of the filler is 75% by volume or more in the total solid content volume.

<11> The resin sheet according to <10>, wherein a surface of the resin sheet has adhesiveness.

<12> The curable component is the resin sheet according to <10> or <11>, which includes an epoxy resin and a curing agent.

<13> A cured resin sheet, which is a cured product of the resin sheet according to any one of <10> to <12>.

<14> A heat radiating member comprising a metal workpiece and the resin sheet according to any one of <10> to <12>.

<15> A heat dissipating member comprising a metal workpiece and the cured resin sheet according to <13>.

  ADVANTAGE OF THE INVENTION According to this invention, the resin sheet which expresses the outstanding heat conductivity, its manufacturing method, and a heat radiating member using the same can be provided.

It is typical sectional drawing which shows an example of the heat radiating member concerning this embodiment. It is process drawing which shows an example of the manufacturing method of the resin sheet hardened | cured material concerning this embodiment.

<Method for producing resin sheet>
The method for producing a resin sheet of the present invention includes a step of forming a filler layer by applying a filler on at least one surface of a first composite sheet containing a curable component and a filler, and curing on the filler layer. A step of laminating a second composite sheet containing a sex component and a filler to obtain a laminate, contacting the first composite sheet and the second composite sheet, and forming the filler layer into the first composite sheet. And a step of embedding in at least one selected from the second composite sheets to obtain a resin sheet. The method for producing the resin sheet may further include other steps as necessary.

  By manufacturing the resin sheet by integrating the two composite sheets in a state where the filler is sandwiched between the two prepared composite sheets, the filling rate of the filler in the obtained resin sheet is drastically improved. And excellent thermal conductivity can be exhibited. Moreover, since the composite sheet is prepared in advance, the moldability of the produced resin sheet is excellent, and the productivity of the resin sheet is also excellent. Hereinafter, the manufacturing method of the resin sheet of this invention is demonstrated in detail. Note that in this specification, the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used if the intended purpose of the process is achieved. included. Moreover, the numerical range shown using "to" shows the range which includes the numerical value described before and behind "to" as a minimum value and a maximum value, respectively. Further, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.

[Composite sheet preparation process]
The method for producing a resin sheet of the present invention preferably further includes a composite sheet preparation step of preparing a first composite sheet containing a curable component and a filler, and a second composite sheet containing a curable component and a filler. . The preparation step of the composite sheet may be a step of appropriately selecting the first composite sheet and the second composite sheet from commercially available products, respectively, and the first composite sheet and the second composite sheet having a desired configuration. It may be a step of manufacturing each composite sheet. The first composite sheet and the second composite sheet may be the same or different from each other. When the first composite sheet and the second composite sheet are different, for example, at least selected from the group consisting of average thickness, type of filler, filler content, type of curable component, content of curable component It is sufficient that one element is different from each other. It is preferable that the first composite sheet and the second composite sheet have the same configuration.

(Curing component)
The first composite sheet and the second composite sheet (hereinafter also simply referred to as “composite sheet”) include at least one curable component. The curable component constituting the composite sheet is preferably curable by heat or light. Examples of the curable component include a thermosetting resin and a photocurable resin. More specifically, a curable resin such as an epoxy resin, a phenol resin, a polyimide resin, or a polyurethane resin can be used. From the viewpoint of excellent adhesiveness, at least one curable resin selected from the group consisting of an epoxy resin and a polyurethane resin is preferable, and from the viewpoint of adhesiveness and electrical insulation, it is more preferable to be at least one epoxy resin. . The curable components contained in the first composite sheet and the second composite sheet may be different from each other or the same.

  Examples of the epoxy resin include bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthalene type epoxy resin, and cyclic aliphatic epoxy resin. Among these, from the viewpoint of increasing the thermal conductivity, it is preferable to use an epoxy resin having a mesogenic group in the molecule, which is a structure that is easily self-aligned, such as a biphenyl group. An epoxy resin having such a mesogenic group in the molecule is disclosed, for example, in JP-A-2005-206814. Examples of the epoxy resin include 1-[(3-methyl-4-oxiranylmethoxy) phenyl] -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene, 1-[(3-methyl-4 -Oxiranylmethoxy) phenyl] -4- (4-oxiranylmethoxyphenyl) benzene, 1,4-bis [4- (oxiranylmethoxy) phenyl] cyclohexane. Among these, 1-[(3-methyl-4-oxiranylmethoxy) phenyl] -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene is preferable from the viewpoint of a low melting temperature.

  When the composite sheet contains an epoxy resin, the content of the epoxy resin is preferably 5% by mass to 25% by mass in the total amount of the non-volatile components of the composite sheet, and is 10% by mass to 20% by mass. Is more preferable.

(Curing agent)
The composite sheet preferably further includes at least one curing agent in addition to the curable resin as a curable component. There is no restriction | limiting in particular as said hardening | curing agent, According to curable resin, it can select suitably. In particular, when the curable resin is an epoxy resin, the curing agent can be appropriately selected from curing agents usually used as a curing agent for epoxy resins. Specific examples include amine curing agents such as dicyandiamide and aromatic diamine; phenolic curing agents such as phenol novolac resin, cresol novolac resin, and catechol resorcinol novolak resin. Among these, from the viewpoint of improving thermal conductivity, a phenolic curing agent is preferable, and a phenolic curing agent including a structure derived from a bifunctional phenol compound such as catechol, resorcinol, or p-hydroquinone is preferable.

  The content of the curing agent in the composite sheet is not particularly limited. For example, the content rate of a hardening | curing agent can be 0.1-2 on an equivalent basis with respect to curable resin, and it is preferable that it is 0.5-1.5. Adhesiveness and heat conductivity can be improved more because the content rate of a hardening | curing agent is the said range.

(Fira)
The composite sheet contains at least one filler. The filler is not particularly limited, and can be appropriately selected from fillers known in the art. The filler may be conductive or non-conductive. The filler may be an organic filler or an inorganic filler. Of these, inorganic fillers are preferred from the viewpoint of thermal conductivity. For example, gold, silver, nickel, copper, etc. are mentioned as a conductive inorganic filler. When a conductive inorganic filler is used, the thermal conductivity can be improved, but the insulation tends to be lowered. Examples of the non-conductive inorganic filler include aluminum oxide (alumina), magnesium oxide, aluminum nitride, boron nitride, silicon nitride, and silicon oxide. One kind of inorganic filler may be used, or two or more kinds of mixed fillers may be used. Moreover, you may use combining the filler which has a different particle size. It is preferably selected from the group consisting of alumina and boron nitride from the viewpoint of high thermal conductivity, and boron nitride is more preferable from the viewpoint of being soft and easy to press. In one embodiment of the present invention, it is preferable to use boron nitride which is soft and has high thermal conductivity as the filler.

  The boron nitride may be, for example, primary particles of boron nitride formed in a scaly shape or secondary particles formed by agglomerating such primary particles. Examples of the boron nitride include hexagonal boron nitride (h-BN), cubic boron nitride (c-BN), and wurtzite boron nitride. Among these, from the viewpoint of high thermal conductivity and low thermal expansion, at least one selected from hexagonal boron nitride (h-BN) and cubic boron nitride (c-BN) is preferable, and from the viewpoint of molding processability, soft Hexagonal boron nitride (h-BN) is more preferable.

  There is no restriction | limiting in particular in the volume average particle diameter of the said boron nitride. Among these, from the viewpoint of high thermal conductivity, those having an average particle diameter of 10 μm to 200 μm are preferable, and those having an average particle diameter of 50 μm to 150 μm are more preferable. When it is 10 μm or more, the thermal conductivity tends to be further improved. It can suppress that the anisotropy of a particle shape becomes it too large that it is 200 micrometers or less. The volume average particle diameter of boron nitride can be measured with a laser scattering diffraction particle size distribution analyzer or the like.

  The filler content contained in the composite sheet is not particularly limited. Among them, the filler content is preferably 50% by volume or more, and preferably 50% by volume to 70% by volume in the total solid volume of the composite sheet from the viewpoint of thermal conductivity and moldability as a resin sheet. Is more preferable, and it is still more preferable that it is 60 volume%-70 volume%. The total solid content volume means the total volume of non-volatile components.

  The types of fillers included in the first composite sheet and the second composite sheet may be different from each other or the same. The filler content in the first composite sheet and the second composite sheet may be different from each other or the same.

(Curing catalyst)
It is preferable that the composite sheet further contains at least one curing catalyst. There is no restriction | limiting in particular as a curing catalyst, According to the kind of curable resin, it can select from the curing catalyst used normally, and can use it. When the curable resin is an epoxy resin, specific examples of the curing catalyst include triphenylphosphine, triphenylphosphine derivatives, 2-ethyl-4-methylimidazole, boron trifluoride amine complex, 1-benzyl-2- And methyl imidazole. Among them, it is preferable to use triphenylphosphine from the viewpoint of achieving high thermal conductivity.

  When the composite sheet further contains a curing catalyst, the content of the curing catalyst is not particularly limited. For example, the content of the curing catalyst can be 0.1% by mass to 2.0% by mass, and preferably 0.5% by mass to 1.5% by mass with respect to the curable resin. Adhesiveness and heat conductivity can be improved more because the content rate of a curing catalyst is the said range.

(solvent)
The composite sheet may further contain at least one solvent. The solvent is not particularly limited as long as it does not inhibit the curing reaction of the curable component, and can be appropriately selected from commonly used organic solvents. Specific examples include ketone solvents such as methyl ethyl ketone and cyclohexanone. The content of the solvent in the composite sheet is not particularly limited, and can be appropriately selected according to the applicability of the composition containing the curable component and the filler.

(Additive)
In addition to the curable component and the filler, the composite sheet may further include other additives other than the curing catalyst and the solvent as described above, as necessary. Examples of other additives include various additives generally used for resin compositions such as coupling agents, elastomers, antioxidants, antioxidants, stabilizers, flame retardants, and thickeners. When the composite sheet further contains additives, the content of these additives is not particularly limited as long as the effects of the present invention are not impaired.

  The average thickness of the composite sheet is not particularly limited and can be appropriately selected according to the purpose. For example, the average thickness of the composite sheet is preferably 100 μm to 200 μm, and more preferably 150 μm to 200 μm. In addition, the average thickness of a composite sheet is calculated | required as an arithmetic average value by measuring thickness of 5 points | pieces using a micrometer.

  The composite sheet is preferably in the A stage state rather than the semi-cured state (B stage state). When the A-stage composite sheet is used, the meltability and fluidity of the resin are better, so that it becomes easier to enter the gap between the fillers sandwiched between the composite sheets during the pressing process, The gap can be sufficiently embedded. The A stage state means that the curable component is in an uncured state. Specifically, when the composite sheet is produced by applying a resin varnish as described later, it means a state after drying at a predetermined temperature for a predetermined time in order to remove the solvent.

(Composite sheet manufacturing method)
The composite sheet can be produced by a generally used method as long as it can form a composition containing a curable component and a filler into a sheet shape. For example, a resin varnish containing a curable resin, a curing agent, a curing catalyst, a solvent, a filler, an additive, and the like is prepared by a conventional method, and this is applied onto a release film such as a PET film and dried to release it. A composite sheet can be formed on the film.

  The method for applying the resin varnish on the release film is not particularly limited, and can be carried out by a known method. Specific examples of the coating method include comma coating, die coating, lip coating, and gravure coating. As a coating method for forming a composition layer with a predetermined thickness, a comma coating method in which an object to be coated is passed between gaps, a die coating method in which a resin varnish whose flow rate is adjusted from a nozzle, or the like is applied. it can. For example, when the thickness of the composition layer before drying is 50 μm to 500 μm, it is preferable to use a comma coating method. The method for drying the composition layer formed by applying the resin varnish is not particularly limited as long as at least a part of the solvent contained in the composition layer can be removed. For example, the method of drying the composition layer can be a heat treatment at 100 to 150 ° C. for 10 to 30 minutes.

[Filler layer formation process]
The manufacturing method of the resin sheet of this invention has a filler layer formation process which provides a filler and forms a filler layer on the at least one surface of the 1st composite sheet containing a sclerosing | hardenable component and a filler. When the first composite sheet is formed on a release film, a filler layer is formed by applying a filler on the surface of the composite sheet opposite to the surface facing the release film.

  The filler provided on the surface of the first composite sheet is not particularly limited, and can be appropriately selected from fillers known in the art. The filler may be conductive or non-conductive. The filler may be an organic filler or an inorganic filler. Of these, inorganic fillers are preferred from the viewpoint of thermal conductivity. For example, gold, silver, nickel, copper, etc. are mentioned as a conductive inorganic filler. When a conductive inorganic filler is used, the thermal conductivity can be improved, but the insulation tends to be lowered. Examples of the non-conductive inorganic filler include aluminum oxide (alumina), magnesium oxide, aluminum nitride, boron nitride, silicon nitride, and silicon oxide. One kind of inorganic filler may be used, or two or more kinds of mixed fillers may be used. Moreover, you may use combining the filler which has a different particle size. It is preferably selected from the group consisting of alumina and boron nitride from the viewpoint of high thermal conductivity, and boron nitride is more preferable from the viewpoint of being soft and easy to press. In one embodiment of the present invention, it is preferable to use boron nitride which is soft and has high thermal conductivity as the filler. The details and preferred embodiments of boron nitride are the same as boron nitride in the composite sheet.

  The kind of filler provided on the first composite sheet may be different from or different from the filler constituting the first or second composite sheet. It is preferable to use the same type of filler.

  The amount of filler applied on the first composite sheet is not particularly limited. The total amount of the filler contained in each of the first composite sheet and the second composite sheet and the filler applied on the first composite sheet is 75% by volume or more in the total solid content volume of the resin sheet. It is preferable that the volume is 75% by volume to 95% by volume, and more preferably 75% by volume to 90% by volume. By adjusting the amount of filler applied on the first composite sheet so that the total amount of filler contained in the resin sheet is 75% by volume or more, the filler becomes more highly filled and has better thermal conductivity. Tend to develop. On the other hand, by adjusting the amount of filler applied on the first composite sheet so that the total amount of filler contained in the resin sheet is 95% by volume or less, the applied filler is sufficiently embedded in the composite sheet. Thus, the moldability of the resin sheet tends to be further improved. The total solid content volume means the total volume of the components constituting the two composite sheets and the non-volatile components contained in the filler sandwiched between the composite sheets.

  The method for applying the filler on the first composite sheet is not particularly limited. Among these, the method for imparting filler is preferably a method for increasing the uniformity of filler distribution. Further, the state of the filler to be applied may be a powder state or a state dispersed in a medium. Specific examples of the filler application method include a method of applying a powdery filler so that the distribution is uniform through a sieve. The sieve used in applying the filler is not particularly limited, and can be appropriately selected according to the average particle diameter of the filler to be applied.

[Step of obtaining laminated body]
On the filler layer formed on the first composite sheet, a second composite sheet is laminated to obtain a laminate in which the first composite sheet, the filler layer, and the second composite sheet are laminated in this order. It is done. When the second composite sheet is formed on the release film, the second composite sheet is arranged such that the surface opposite to the surface facing the release film of the second composite sheet faces the filler layer. Laminate sheets. The size in the surface direction of the second composite sheet to be laminated is preferably the same as the size in the surface direction of the first composite sheet, and the first composite sheet and the second composite sheet have a filler layer. It is more preferable that the non-overlapping portions are stacked in a stacked state.

[Step of obtaining resin sheet]
Next, the first composite sheet and the second composite sheet are brought into contact with each other, and the filler layer of the laminate obtained above is embedded in at least one of the first composite sheet and the second composite sheet. By doing so, a resin sheet is obtained. The obtained resin sheet is derived from the first composite sheet, and the first composite layer having the same filler filling ratio of the first composite layer, and at least one of the first composite sheet and the second composite sheet A filler-filled layer formed by embedding a filler layer and a second composite layer derived from the second composite sheet and having the same filler filling ratio of the second composite layer are laminated in this order. . Since the obtained resin sheet has a curable component on the sheet surface, it can be a resin sheet having good adhesion. That is, the filler high-filling layer and the adherend can be attached with excellent adhesiveness by the curable component present on the surface of the resin sheet.

  The method of bringing the first composite sheet and the second composite sheet into contact with each other is preferably a method of pressing the laminate.

  The temperature of the press treatment is not particularly limited. Among these, the temperature of the press treatment is preferably a temperature at which the curable component contained in the composite sheet can be in a molten state. That is, it is preferable that the temperature of press processing is selected according to the curable component contained in a composite sheet. As a result, the curable component is sufficiently filled in the filler layer sandwiched between the composite sheets.

  The time for the press treatment is not particularly limited. The press treatment time is preferably 1 minute to 10 minutes, more preferably 5 minutes to 10 minutes. When the pressing time is 1 minute or longer, the curable component contained in the composite sheet is sufficiently filled in the filler layer sandwiched between the composite sheets.

  The pressure for the press treatment is not particularly limited. The pressure for the press treatment is preferably 30 MPa to 60 MPa. By pressing at a pressure in this range, the fillers sandwiched between the composite sheets can come into close contact with each other, and the thermal conductivity is increased.

  The press treatment is preferably performed under reduced pressure. The decompression conditions are not particularly limited. For example, the decompression condition is preferably 1 kPa or less.

<Resin sheet>
The resin sheet of this invention is obtained by the manufacturing method of the said resin sheet. The resin sheet is formed by laminating the first composite layer, the filler high filling layer, and the second composite layer in this order. Since the resin sheet has a curable component on the sheet surface, the resin sheet can be a resin sheet having good adhesion. That is, the filler high-filling layer and the adherend can be attached with excellent adhesiveness by the curable component present on the surface of the resin sheet. Moreover, the resin sheet can be cured to a C stage state to form a cured resin sheet having excellent thermal conductivity. Furthermore, the resin sheet hardened | cured material which improved heat conductivity more can be obtained by shaving at least one surface of the obtained resin sheet hardened | cured material. In this case, the obtained resin sheet cured product can have more excellent thermal conductivity by scraping the surface of the cured resin sheet so that the cured layer derived from the filler high filling layer remains.

  The average thickness of the resin sheet is not particularly limited and can be appropriately selected according to the purpose. For example, the average thickness of the resin sheet is preferably 100 μm to 500 μm, and more preferably 100 μm to 300 μm. In addition, the average thickness of the resin sheet is obtained as an arithmetic average value by measuring the thickness of five points using a micrometer.

<Hardened resin sheet>
The cured resin sheet of the present invention is a cured product of the resin sheet, and is obtained by curing the resin sheet to a C-stage state. The curing temperature and the curing time can be appropriately selected according to the configuration of the composite sheet constituting the resin sheet. For example, it can be 2 to 4 hours at 160 ° C to 190 ° C. Furthermore, you may perform a hardening process on several heating temperature conditions.

  In order to prevent oxidation of the curable component during the curing process, it is preferable to attach a metal plate or a metal foil to both sides in the pressing stage before curing. After curing, the metal plate or metal foil can be removed by etching or the like. The metal plate and the metal foil are not particularly limited. For example, a copper plate, copper foil, etc. are mentioned.

  The obtained resin sheet cured product has a sandwich structure. That is, both surfaces of the cured resin sheet are a cured layer derived from the first composite layer and a cured layer derived from the second composite layer, respectively, and a cured layer derived from the first and second composite layers. The part between is a hardened layer derived from the filler high filling layer. The cured resin sheet is a highly thermally conductive resin sheet cured product in which at least a part of the cured layer derived from the composite layer on both sides of the cured resin sheet is removed so that the filler is more highly filled. There may be. The method for removing the cured layer derived from the composite layer is not particularly limited. For example, a diamond polishing apparatus can be used. Abrasive paper having a predetermined roughness can also be used.

  The cured resin sheet and the cured resin sheet having high thermal conductivity may be used by being bonded to an adherend through a cured layer derived from the composite layer remaining on the surface, or may be adhered via grease or the like. You may stick and use a body.

  An example of a method for producing the cured resin sheet will be described with reference to the drawings. In FIG. 2, a resin varnish is obtained by mixing a resin that is a curable component, a solvent, and a filler. The obtained resin varnish is coated on a polyethylene terephthalate film (PET film) with a bar coater or the like to form a resin composition layer. A solvent is removed from the obtained resin composition layer by a drying treatment to obtain a first composite sheet as an A stage sheet. The PET film is peeled off from the obtained A stage sheet, a copper foil is pasted on one surface, and filler is spread on the other surface to form a filler layer. A resin sheet is obtained by laminating an A stage sheet, which is the second composite sheet, and a copper foil on the filler layer and pressing the laminate. The obtained resin sheet is cured to obtain a cured resin sheet having copper foil on both sides. Next, the cured resin sheet can be produced by removing the copper foils on both sides by etching.

<Heat dissipation member>
The 1st aspect of the heat radiating member of this invention is equipped with a metal workpiece and the said resin sheet arrange | positioned in contact with the said metal workpiece. Moreover, the 2nd aspect of the member for thermal radiation of this invention is equipped with a metal workpiece and the said resin sheet hardened | cured material arrange | positioned in contact with the said metal workpiece. The heat radiating member may further include other elements as necessary. Here, the “metal workpiece” means a molded product made of a metal material that can function as a heat dissipation member, including a metal foil, a substrate, a fin, and the like. For example, a substrate composed of various metals such as Al and Cu is preferable. FIG. 1 shows a schematic cross-sectional view of an example of a heat radiating member using the resin sheet of the present invention.

  In FIG. 1, a resin sheet 20 is disposed between a first metal workpiece 10 made of, for example, Cu and a second metal workpiece 30 made of, for example, Al, and one surface thereof is on the surface of the metal workpiece 10. The other surface is bonded to the surface of the metal work 30. Since the resin sheet 20 has excellent thermal conductivity, for example, the heat generated from the first metal workpiece 10 made of Cu is transferred to the second metal workpiece 30 side made of Al via the resin sheet 20. It is possible to conduct heat efficiently and to dissipate heat to the outside. Although the heat radiating member provided with the resin sheet is illustrated in FIG. 1, the heat radiating member may be configured by providing a cured resin sheet instead of the resin sheet.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Preparation of catechol resorcinol novolak (CRN) resin)
Into a 3 L separable flask equipped with a stirrer, a cooler, and a thermometer, 594 g of resorcinol, 66 g of catechol, 316.2 g of 37% by mass formalin, 15 g of oxalic acid, and 100 g of water were added and heated to 100 ° C. while heating in an oil bath. The temperature was raised and the reaction was continued for 4 hours at the reflux temperature.
Thereafter, the temperature in the flask was raised to 170 ° C. while distilling off water. The reaction was continued for 8 hours while maintaining 170 ° C. Thereafter, concentration was performed under reduced pressure for 20 minutes to remove water and the like in the system, and a catechol resorcinol novolak (CRN) resin was taken out. The obtained catechol resorcinol novolak (CRN) resin had a number average molecular weight of 530 and a weight average molecular weight of 930. The phenol equivalent of the phenol resin is 65 g / eq. Met.

<Example 1>
(1) Production of Composite Sheet In a plastic bottle, 4.119 parts by mass (solid content 50% by mass) of cyclohexanone dissolved in catechol resorcinol novolak (CRN) resin prepared in advance as a curing agent and 1- (3 as epoxy resin 1-{(3-methyl-4-oxiranylmethoxy) phenyl} -4 synthesized by a conventional method from -methyl-4-hydroxyphenyl) -4- (4-hydroxyphenyl) -1-cyclohexene and epichlorohydrin -(4-oxiranylmethoxyphenyl) -1-cyclohexene 6.6775 parts by mass, triphenylphosphine 0.0707 parts by mass (manufactured by Wako Pure Chemical Industries), and cyclohexanone 25.90 parts by mass (manufactured by Wako Pure Chemical Industries) Added and mixed. Thereafter, 37.38 parts by mass of boron nitride particles (volume average particle diameter of 40 μm, manufactured by Mizushima Alloy Iron Co., Ltd., trade name “HP-40MF100”) as a filler is added and further mixed to form a composite sheet coating liquid (resin varnish). Obtained.
In addition, the content rate of the filler in the total solid content volume of the resin varnish was 70 volume%.

  Thickness of the obtained composite sheet coating solution on the release surface of a polyethylene terephthalate film (Fujimori Kogyo Co., Ltd., 75E-0010CTR-4, hereinafter simply abbreviated as “PET film”) with an applicator. It apply | coated so that it might become about 200 micrometers, and it was made to dry for 10 minutes with a 100 degreeC box-type oven, and formed the composite sheet of the A stage state on PET film. The average thickness of the obtained composite sheet was 150 μm. In addition, the average thickness of the composite sheet was obtained as an arithmetic average value by measuring the thickness of five points using a micrometer.

(2) Production of resin sheet and cured resin sheet A composite sheet (A stage, obtained by the above-described method on the roughened surface of a copper foil (5 cm × 5 cm, manufactured by Furukawa Electric Co., Ltd., GTS foil) having a thickness of 85 μm. 5 cm × 5 cm) were aligned and overlapped so that the copper foil and the composite sheet just overlapped, and then the PET film was peeled off. On the composite sheet, 0.5 parts by mass of the same boron nitride particles as described above were directly sprayed using a sieve so as to be evenly distributed to form a filler layer. Next, on the filler layer, another composite sheet is aligned and overlapped so as to overlap the composite sheet on the copper foil, and then the PET film is peeled off, and the same copper foil as described above is further stacked. Got. The obtained laminate was pressed by a high-temperature vacuum press under the conditions of a temperature of 180 ° C., a degree of vacuum ≦ 1 kPa, a pressure of 60 MPa, and a time of 10 minutes to obtain a resin sheet having copper foil on both sides. The resin sheet after the press treatment was put in an oven, and a cured resin sheet having a copper foil on both sides was obtained by step curing at 160 ° C. for 30 minutes and then at 190 ° C. for 2 hours. From the obtained resin sheet cured product having copper foil on both surfaces, the copper foil was etched away using a sodium persulfate solution to obtain a resin sheet cured product having a sandwich structure. The average thickness of the obtained cured resin sheet was 300 μm. In addition, the average thickness of the cured resin sheet was obtained as an arithmetic average value by measuring the thickness of five points using a micrometer.

<Evaluation>
About the resin sheet hardened | cured material obtained above, the following evaluation was performed. The results are shown in Table 1. "-" In Table 1 indicates that it has not been evaluated.

(Thermal conductivity)
About the obtained resin sheet hardened | cured material, the heat resistance value of the resin sheet hardened | cured material was measured using the Yamayo Tester Co., Ltd. product (YST-901S) heat resistance evaluation apparatus. The thermal conductivity (W / m · K) was calculated by back-calculating the obtained thermal resistance value.
The heat conductivity of the cured resin sheet was 20.0 W / mK.

(Dielectric breakdown voltage)
About the obtained resin sheet cured | curing material, the dielectric breakdown voltage was measured using the dielectric breakdown test apparatus (SOKEN insulation material test system DAC-6032C). The measurement was performed with a cylindrical electrode having a diameter of 10 mm, and the pressure increase rate was 500 V / s, the alternating current was 50 Hz, the cut-off current was 10 mA, room temperature, and oil.
The dielectric breakdown voltage (BDV) of the cured resin sheet was 60 kV / mm or more.

(Shear strength)
A composite sheet (A stage, 5 cm × 5 cm) obtained by the above-described method was stacked on a 7 cm × 7 cm aluminum plate (thickness 3 mm), and the PET film was peeled off. Further, a filler layer was formed by directly spraying 0.5 parts by mass of the same boron nitride particles as the filler from above the composite sheet using a sieve so as to be evenly distributed. Another composite sheet (A stage, 5 cm × 5 cm) was aligned and overlapped so as to overlap the composite sheet on the aluminum plate. Further, a 3.4 cm × 3.0 cm copper plate was stacked to obtain a laminate. The obtained laminate was pressure-bonded by a high-temperature vacuum press under the conditions of a temperature of 180 ° C., a degree of vacuum ≦ 1 kPa, a pressure of 60 MPa, and a time of 10 minutes. The sample after the pressure-bonding treatment was put in an oven and post-cured by step curing at 160 ° C. for 30 minutes and at 190 ° C. for 2 hours to prepare a metal substrate to which the resin sheet cured product was attached.
The shear bond strength of the metal substrate to which the cured resin sheet thus obtained was attached was measured using a Tensilon universal testing machine “RTC-1350A” manufactured by Orientec Co., Ltd. The measurement was performed by peeling the aluminum plate and the copper plate at a test speed of 1 mm / min at room temperature.
The sheared adhesive strength of the obtained resin sheet cured product was 1.5 MPa.

(Fila content)
Using a differential thermogravimetric analyzer (TG / DTA6300) manufactured by Vacuum Riko Co., Ltd., the mass content of the thermal decomposition of the resin component is measured for the filler content in the cured resin sheet having the sandwich structure obtained by the above method. Calculated by. The measurement was performed by heating from 30 ° C. to 700 ° C. in nitrogen at a constant rate of 10 ° C./min.
The filler content of the obtained cured resin sheet was 75% by volume.

(Formability)
A resin sheet that was considered to be good in handling and would not cause a problem during molding was evaluated as “◯”, and a resin sheet that required careful handling or was unable to be molded into a resin sheet was determined as “x”.

<Example 2>
(1) Preparation of composite sheet In a plastic bottle, 2.2142 parts by mass (solid content 50% by mass) of a catechol resorcinol novolak (CRN) resin prepared in advance as a curing agent and a general-purpose epoxy resin EPPN-502H 3.0000 parts by mass (manufactured by Nippon Kayaku), 0.0329 parts by mass of triphenylphosphine (manufactured by Wako Pure Chemical Industries), and 12.03 parts by mass of cyclohexanone (manufactured by Wako Pure Chemical Industries, Ltd.) were added and mixed. Thereafter, 17.57 parts by mass of boron nitride particles (volume average particle diameter of 40 μm, manufactured by Mizushima Alloy Iron Co., Ltd., trade name “HP-40MF100”) were added as fillers and further mixed to form a composite sheet coating solution (resin varnish). Got.
In addition, the content rate of the filler in the total solid content volume of the resin varnish was 70 volume%.

  The obtained composite sheet coating solution was applied on the release surface of the PET film with an applicator so that the thickness was about 200 μm, and dried in a box oven at 100 ° C. for 10 minutes. A composite sheet in a stage state was formed. The average thickness of the obtained composite sheet was 150 μm.

(2) Production of resin sheet and cured resin sheet A composite sheet (A stage, obtained by the above-described method on the roughened surface of a copper foil (5 cm × 5 cm, manufactured by Furukawa Electric Co., Ltd., GTS foil) having a thickness of 85 μm. 5 cm × 5 cm) were aligned and overlapped so that the copper foil and the composite sheet just overlapped, and then the PET film was peeled off. On the composite sheet, 0.5 parts by mass of the same boron nitride particles as described above were directly sprayed using a sieve so as to be evenly distributed to form a filler layer. Next, on the filler layer, another composite sheet is aligned and overlapped so as to overlap the composite sheet on the copper foil, and then the PET film is peeled off, and the same copper foil as described above is further stacked. Got. The obtained laminate was pressed by a high-temperature vacuum press under the conditions of a temperature of 180 ° C., a degree of vacuum ≦ 1 kPa, a pressure of 60 MPa, and a time of 10 minutes to obtain a resin sheet having copper foil on both sides. The resin sheet after the press treatment was put in an oven, and a cured resin sheet having a copper foil on both sides was obtained by step curing at 160 ° C. for 30 minutes and then at 190 ° C. for 2 hours. From the obtained resin sheet cured product having copper foil on both surfaces, the copper foil was etched away using a sodium persulfate solution to obtain a resin sheet cured product having a sandwich structure. The average thickness of the obtained cured resin sheet was 300 μm.

The obtained cured resin sheet was evaluated in the same manner as in Example 1. The thermal conductivity of the cured resin sheet having the sandwich structure obtained above was 13.0 W / mK. The dielectric breakdown voltage (BDV) was 60 kV / mm or more.
Moreover, the shear bond strength of the obtained cured resin sheet was 1.3 MPa.
Moreover, the filler content rate of the obtained resin sheet cured | curing material was 75 volume%.

<Comparative Example 1>
(Production of composite sheet)
In a plastic bottle, a cyclohexanone-dissolved product of catechol resorcinol novolak (CRN) resin prepared in advance as a curing agent, 4.119 parts by mass (solid content 50% by mass), and 1- (3-methyl-4-hydroxyphenyl) -4 1-{(3-methyl-4-oxiranylmethoxy) phenyl} -4- (4-oxiranylmethoxyphenyl) synthesized by a conventional method from-(4-hydroxyphenyl) -1-cyclohexene and epichlorohydrin -1-cyclohexene 6.6775 mass parts (epoxy resin), triphenylphosphine 0.0707 mass parts (made by Wako Pure Chemical Industries), and cyclohexanone 33.98 mass parts (made by Wako Pure Chemical Industries) were added and mixed. Thereafter, 48.05 parts by mass of boron nitride particles (volume average particle diameter of 40 μm, manufactured by Mizushima Alloy Iron Co., Ltd., trade name “HP-40MF100”) as a filler is added and further mixed to form a composite sheet coating solution (resin varnish) Got.
In addition, the content rate of the filler in the total solid content volume of the resin varnish was 75 volume%.

When the obtained composite sheet coating liquid was applied with an applicator so that the thickness was about 200 μm on the release surface of the PET film, the viscosity of the resin varnish became too high due to the high filler content, It could not be applied uniformly. When the coated surface was observed, filler aggregates were observed. Subsequently, it was dried in a box oven at 100 ° C. for 10 minutes, but a sheet having poor sheet formability and a fragile composite sheet was obtained.
The obtained composite sheet was poor in handleability and could not withstand subsequent processes and evaluations.

<Comparative example 2>
(Production of composite sheet)
In a plastic bottle, 2.2142 parts by mass (solid content 50% by mass) of a pre-prepared catechol resorcinol novolak (CRN) resin and 2.000 parts by mass of a general-purpose epoxy resin EPPN-502H (manufactured by Nippon Kayaku) ), 0.0329 parts by mass of triphenylphosphine (manufactured by Wako Pure Chemical Industries), and 15.84 parts by mass of cyclohexanone (manufactured by Wako Pure Chemical Industries, Ltd.) were added and mixed. Thereafter, 22.59 parts by mass of boron nitride particles (volume average particle diameter of 40 μm, manufactured by Mizushima Alloy Iron Co., Ltd., trade name “HP-40MF100”) as a filler is added and further mixed to form a composite sheet coating liquid (resin varnish) Got.
In addition, the content rate of the filler in the total solid content volume of the resin varnish was 75 volume%.

When the obtained composite sheet coating liquid was applied with an applicator so that the thickness was about 200 μm on the release surface of the PET film, the viscosity of the resin varnish became too high due to the high filler content, It could not be applied uniformly. When the coated surface was observed, filler aggregates were observed. Subsequently, it was dried in a box oven at 100 ° C. for 10 minutes, but a sheet having poor sheet formability and a fragile composite sheet was obtained.
The obtained composite sheet was poor in handleability and could not withstand subsequent processes and evaluations.

<Comparative Example 3>
In Example 1, a resin sheet cured product was produced and evaluated in the same manner as in Example 1 except that no filler was applied when two composite sheets were stacked.
The heat conductivity of the cured resin sheet was 10.1 W / mK. The dielectric breakdown voltage (BDV) was 30 kV / mm or more.
Moreover, the shear bond strength of the obtained resin sheet cured product was 1.7 MPa.
Moreover, the filler content rate of the obtained resin sheet cured | curing material was 70 volume%.

From the above, it can be seen that by using the production method of the present invention, it is possible to produce a resin sheet with a high filler filling (for example, 75% by volume or more) with good moldability. Moreover, it turns out that the resin sheet hardened | cured material formed using the manufacturing method of this invention is highly filled with a filler, and has the outstanding heat conductivity.
Moreover, it turns out that preparation of the resin sheet whose filler content rate is 75 volume% or more is difficult by a normal method.

10 First metal workpiece 20 Resin sheet 30 Second metal workpiece

Claims (15)

Providing a filler on at least one surface of the first composite sheet containing a curable component and a filler to form a filler layer;
A step of laminating a second composite sheet containing a curable component and a filler on the filler layer to obtain a laminate;
Contacting the first composite sheet and the second composite sheet, and embedding the filler layer in at least one selected from the first composite sheet and the second composite sheet; and obtaining a resin sheet; ,
The manufacturing method of the resin sheet which has this.   The method for producing a resin sheet according to claim 1, wherein the step of obtaining the resin sheet includes press treatment.   The method for producing a resin sheet according to claim 1 or 2, wherein the curable components of the first composite sheet and the second composite sheet each independently include an epoxy resin and a curing agent.   The said resin sheet is a manufacturing method of the resin sheet of any one of Claims 1-3 whose content rate of a filler is 75 volume% or more in a total solid content volume.   The resin sheet obtained by the manufacturing method of any one of Claims 1-4.   A cured resin sheet, which is a cured product of the resin sheet according to claim 5.   A cured resin sheet obtained by removing a part of the cured product from at least one surface of the cured product of the resin sheet according to claim 5.   A member for heat dissipation provided with a metal work and the resin sheet according to claim 5 arranged in contact with the metal work.   A heat dissipation member comprising a metal workpiece and the cured resin sheet according to claim 7 disposed in contact with the metal workpiece.   A resin sheet comprising a curable component and a filler, wherein the content of the filler is 75% by volume or more in the total solid volume.   The resin sheet according to claim 10, wherein a surface of the resin sheet has adhesiveness.   The resin sheet according to claim 10 or 11, wherein the curable component includes an epoxy resin and a curing agent.   A cured resin sheet, which is a cured product of the resin sheet according to any one of claims 10 to 12.   A heat radiating member comprising a metal workpiece and the resin sheet according to any one of claims 10 to 12 disposed in contact with the metal workpiece.   A heat dissipating member comprising a metal workpiece and the cured resin sheet according to claim 13 disposed in contact with the metal workpiece.