JP2013048155A - Method for manufacturing metal base substrate and method for manufacturing liquid crystal polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a liquid crystal polyester film excellent in thermal conductivity and withstand voltage property even when a pressure applied during a pressing process of the method is low, and a method capable of manufacturing a metal base substrate including the liquid crystal polyester film.SOLUTION: In the method for manufacturing a liquid crystal polyester film, a liquid crystal polyester liquid composition is coated on a conductive foil 13, the liquid crystal polyester liquid composition containing liquid crystal polyesters, heat conduction fillers and a solvent while the proportion of the heat conduction fillers in the total content of the liquid crystal polyesters and the heat conduction fillers is 50-80 vol.%, the solvent is removed from the coated liquid composition to form a liquid polyester-containing layer 12', the conductive foil 13 and the liquid crystal polyester-containing layer 12' are pressed, the liquid crystal polyester-containing layer 12' after pressing is subjected to heat treatment to form an insulation layer 12 on the conductive foil 13, and a metal layer 11 is provided on the insulation layer 12 by heat pressing to form a metal base substrate 1. A liquid crystal polyester film is obtained by removing the conductive foil 13 and the metal layer 11 from the metal base substrate 1.

Description

  The present invention relates to a metal base substrate excellent in thermal conductivity and voltage resistance and a method for producing a liquid crystal polyester film.

  In response to the recent progress in high-density mounting of electronic components such as power transistors and hybrid ICs, the purpose of stabilizing the operation of these electronic components is to diffuse the heat generated by these electronic components, Development of heat dissipation materials such as metal base substrates and heat dissipation films for efficient heat dissipation is underway.

  The metal base substrate is used when electronic components are mounted, and an insulating layer having thermal conductivity is provided between the metal layer and the conductive foil to electrically insulate them. is there. The heat dissipation film is provided between the electronic component and the heat dissipation component such as a heat dissipation fin in order to conduct heat.

  The metal base substrate can be manufactured, for example, by providing an insulating layer on a conductive foil, and overlapping and pressing the metal layer on the insulating layer. A heat dissipation film can be manufactured in the same manner. For example, an insulating layer is provided on one base material, the other base material is stacked on the insulating layer and pressed, and the insulating layer is used as a heat dissipation film. It can manufacture by removing.

  On the other hand, as the insulating layer and the heat dissipation film (hereinafter collectively referred to as “insulating layer etc.”), the same materials can be used, for example, silicone containing boron nitride or aluminum oxide as a heat conductive filler. Rubber, epoxy resin, and the like have been proposed (see Patent Document 1). In addition, it has been proposed to improve the thermal conductivity by using liquid crystal polyester as a resin component as compared with the case of using a general-purpose resin such as an epoxy resin (see Patent Document 2).

JP 2003-60134 A International Publication No. 10/117033

  However, as described in Patent Documents 1 and 2, when an insulating layer or the like includes a heat conductive filler, a high pressure is required in the pressing process as described above when manufacturing a metal base substrate or a heat dissipation film. There was a problem. This is because if the pressure in the pressing process is low, the thermal conductivity and voltage resistance of the insulating layer and the like are lowered, and the heat dissipation and reliability are lowered. Moreover, when the pressure in a press process is high, there existed a problem that productivity of a metal base substrate and a thermal radiation film will become low. Therefore, as a heat dissipation film with a high heat dissipation effect, development of a method for manufacturing a liquid crystal polyester film containing a heat conductive filler and a metal base substrate having such a film as an insulating layer at a low pressure in the pressing process. Was desired.

  The present invention has been made in view of the above circumstances, and can manufacture a liquid crystal polyester film excellent in thermal conductivity and voltage resistance and a metal base substrate having the same even if the pressure in the pressing process is low. It is an object to provide a method.

To solve the above problem,
The present invention is a method for producing a metal base substrate comprising a liquid crystal polyester and a heat conductive filler, an insulating layer, a conductive foil, and a metal layer, comprising the liquid crystal polyester, the heat conductive filler and a solvent, A liquid crystal polyester liquid composition in which the ratio of the heat conductive filler to the total content of the liquid crystal polyester and the heat conductive filler is 50 to 80% by volume is applied onto the conductive foil, and the solvent is removed from the applied liquid composition. Removing the film and forming a liquid crystal polyester-containing layer, a first press step of pressing the conductive foil and the liquid crystal polyester-containing layer, and heat-treating the liquid crystal polyester-containing layer after the first press step, A heat treatment step of forming an insulating layer on the conductive foil; and a second pressing step of providing a metal layer on the insulating layer by a heat press. It provides a method for producing a metal-based substrate that.
In the manufacturing method of the metal base substrate of this invention, it is preferable that the press in said 1st press process is a heat press at 60-250 degreeC.
In the manufacturing method of the metal base substrate of this invention, it is preferable that the solvent content of the said liquid-crystal polyester content layer is 5-15 mass%.
In the metal base substrate manufacturing method of the present invention, it is preferable that the heat conductive filler is at least one selected from the group consisting of aluminum oxide, aluminum nitride, and boron nitride.
In the manufacturing method of the metal base substrate of this invention, it is preferable that the said liquid crystalline polyester has a repeating unit represented by following General formula (1), (2) and (3).
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
(3) ^-X-Ar 3 -Y-
(In the formula, Ar ¹ is a phenylene group, a naphthylene group or a biphenylylene group; Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylylene group or a group represented by the following general formula (4): Yes; X and Y are each independently an oxygen atom or imino group; one or more hydrogen atoms in Ar ¹ , Ar ² and Ar ³ are each independently substituted with a halogen atom, an alkyl group or an aryl group May be.)
(4) -Ar ⁴ -Z-Ar ^5-
(In the formula, Ar ⁴ and Ar ⁵ are each independently a phenylene group or a naphthylene group; Z is an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)
In the method for producing a metal base substrate of the present invention, the liquid crystalline polyester comprises 30 to 80 mol% of the repeating unit represented by the general formula (1) with respect to the total amount of all repeating units constituting the liquid crystal polyester. It is preferable to have 10 to 35 mol% of the repeating unit represented by the general formula (2) and 10 to 35 mol% of the repeating unit represented by the general formula (3).
In the method for producing a metal base substrate of the present invention, in the general formula (3), X and / or Y are preferably imino groups.
Moreover, this invention is a manufacturing method of the liquid crystalline polyester film containing a heat conductive filler, Comprising: Liquid crystal polyester, a heat conductive filler, and a solvent, It occupies for the total content of the said liquid crystal polyester and a heat conductive filler. A liquid crystal polyester liquid composition having a heat conductive filler ratio of 50 to 80% by volume is applied onto the first heat-resistant substrate, and the solvent is removed from the applied liquid composition to form a liquid crystal polyester-containing layer. A drying step to form, a first press step for pressing the first heat-resistant substrate and the liquid crystal polyester-containing layer, and heat treatment of the liquid crystal polyester-containing layer after the first press step, A heat treatment process for forming a liquid crystal polyester film on a heat resistant substrate and a second pre-treatment in which a second heat resistant substrate is provided on the liquid crystal polyester film by a heat press. A step, and removing the first and second heat-resistant base member, to provide a manufacturing method of a liquid crystal polyester film and having a film step to obtain a liquid crystal polyester film, a.

  ADVANTAGE OF THE INVENTION According to this invention, even if the pressure in a press process is low, the manufacturing method which can manufacture the liquid crystalline polyester film excellent in heat conductivity and withstand voltage property, and a metal base substrate provided with the same can be provided.

It is a schematic sectional drawing which illustrates a metal base substrate. It is a schematic sectional drawing for demonstrating the manufacturing method of the metal base substrate which concerns on this invention. In the manufacturing method shown in FIG. 2, it is a schematic sectional drawing for demonstrating the method of pressing a conductive foil and a liquid crystal polyester content layer.

<Production method of metal base substrate>
A method of manufacturing a metal base substrate according to the present invention is a method of manufacturing a metal base substrate including a liquid crystal polyester and a heat conductive filler, an insulating layer, a conductive foil, and a metal layer. A liquid crystal polyester liquid composition containing a material and a solvent and having a ratio of the heat conductive filler to the total content of the liquid crystal polyester and the heat conductive filler of 50 to 80% by volume is applied onto the conductive foil, A drying step of removing the solvent from the applied liquid composition to form a liquid crystal polyester-containing layer, a first press step of pressing the conductive foil and the liquid crystal polyester-containing layer, and the liquid crystal polyester after the first press step A heat treatment step of heat-treating the containing layer to form an insulating layer on the conductive foil, and a second pre-treatment in which a metal layer is provided on the insulating layer by a heat press. And having a step. By performing the pressing process twice and lowering the pressure in each pressing process, a metal base substrate excellent in thermal conductivity and voltage resistance can be obtained.
Hereinafter, the present invention will be described in detail for each step with reference to the drawings. In the present specification, the “film” includes a very thin film to a thick sheet unless otherwise specified.

FIG. 1 is a schematic cross-sectional view illustrating a metal base substrate.
In the metal base substrate 1 shown here, an insulating layer 12 and a conductive foil 13 are laminated in this order on a metal layer 11 as a base material.
Hereinafter, the manufacturing method of the metal base board | substrate 1 which concerns on this invention is demonstrated, referring FIG.

[Drying process]
In the drying step, the liquid crystal polyester liquid composition is applied onto the conductive foil 13, the solvent is removed from the applied liquid composition, and the liquid crystal polyester-containing layer 12 ′ is formed as shown in FIG. Form.
What is necessary is just to adjust the thickness after application | coating of the said liquid composition suitably considering the thickness of the insulating layer 12 mentioned later.

The conductive foil 13 forms, for example, a circuit wiring pattern, and is preferably a metal foil from the viewpoint of easy handling of materials, simple formation, and excellent economy, and the material thereof is copper, aluminum, Silver or an alloy containing one or more metals selected from these is preferable, and copper or a copper alloy is more preferable.
The thickness of the conductive foil 13 is preferably 15 to 500 μm.

  The liquid composition contains liquid crystal polyester, a heat conductive filler and a solvent, and the liquid crystal polyester is preferably dissolved in the solvent.

  The liquid crystalline polyester in the liquid composition is a liquid crystalline polyester exhibiting liquid crystallinity in a molten state, and is preferably melted at a temperature of 450 ° C. or lower. The liquid crystal polyester may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, or a liquid crystal polyester imide. The liquid crystal polyester is preferably a wholly aromatic liquid crystal polyester using only an aromatic compound as a raw material monomer.

As a typical example of liquid crystal polyester,
(I) An aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine are polymerized (polycondensed). thing,
(II) a polymer obtained by polymerizing plural kinds of aromatic hydroxycarboxylic acids,
(III) A polymer obtained by polymerizing an aromatic dicarboxylic acid and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine and an aromatic diamine,
(IV) What polymerizes polyester, such as a polyethylene terephthalate, and aromatic hydroxycarboxylic acid is mentioned. Here, the aromatic hydroxycarboxylic acid, the aromatic dicarboxylic acid, the aromatic diol, the aromatic hydroxyamine, and the aromatic diamine are each independently replaced with a part or all of the polymerizable derivative. Also good.

Examples of polymerizable derivatives of a compound having a carboxyl group such as aromatic hydroxycarboxylic acid and aromatic dicarboxylic acid include those obtained by converting a carboxyl group into an alkoxycarbonyl group or an aryloxycarbonyl group (ester), carboxyl Examples include those obtained by converting a group into a haloformyl group (acid halide), and those obtained by converting a carboxyl group into an acyloxycarbonyl group (acid anhydride).
Examples of polymerizable derivatives of hydroxyl group-containing compounds such as aromatic hydroxycarboxylic acids, aromatic diols and aromatic hydroxyamines include those obtained by acylating hydroxyl groups and converting them to acyloxyl groups (acylated products) ).
Examples of polymerizable derivatives of amino group-containing compounds such as aromatic hydroxyamines and aromatic diamines include those obtained by acylating an amino group and converting it to an acylamino group (acylated product).

  The liquid crystalline polyester preferably has a repeating unit represented by the following general formula (1) (hereinafter sometimes referred to as “repeating unit (1)”). The repeating unit (1) and the following general formula (2) ) (Hereinafter sometimes referred to as “repeat unit (2)”) and a repeat unit represented by the following general formula (3) (hereinafter referred to as “repeat unit (3)”). More preferably).

(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
(3) ^-X-Ar 3 -Y-
(In the formula, Ar ¹ is a phenylene group, a naphthylene group or a biphenylylene group; Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylylene group or a group represented by the following general formula (4): Yes; X and Y are each independently an oxygen atom or imino group; one or more hydrogen atoms in Ar ¹ , Ar ² and Ar ³ are each independently substituted with a halogen atom, an alkyl group or an aryl group May be.)
(4) -Ar ⁴ -Z-Ar ^5-
(In the formula, Ar ⁴ and Ar ⁵ are each independently a phenylene group or a naphthylene group; Z is an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)

As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned.
Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, An n-heptyl group, a 2-ethylhexyl group, an n-octyl group, an n-nonyl group, and an n-decyl group may be mentioned, and the number of carbon atoms is preferably 1-10.
Examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naphthyl group, and the carbon number thereof is 6 to 20. Is preferred.
When the hydrogen atom is substituted with these groups, the number is preferably 2 or less independently for each of the groups represented by Ar ¹ , Ar ² or Ar ^3. More preferably.

  Examples of the alkylidene group include a methylene group, an ethylidene group, an isopropylidene group, an n-butylidene group, and a 2-ethylhexylidene group, and preferably have 1 to 10 carbon atoms.

The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. As repeating unit (1), Ar ¹ is a 1,4-phenylene group (repeating unit derived from p-hydroxybenzoic acid), and Ar ¹ is a 2,6-naphthylene group (6-hydroxy). Preferred is a repeating unit derived from 2-naphthoic acid.

The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (2), Ar ² is a 1,4-phenylene group (repeating unit derived from terephthalic acid), Ar ² is a 1,3-phenylene group (repeating unit derived from isophthalic acid) ), Ar ² is a 2,6-naphthylene group (repeating unit derived from 2,6-naphthalenedicarboxylic acid), and Ar ² is a diphenyl ether-4,4′-diyl group (diphenyl) Preferred is a repeating unit derived from ether-4,4′-dicarboxylic acid).

The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine. As the repeating unit (3), Ar ³ is a 1,4-phenylene group (a repeating unit derived from hydroquinone, p-aminophenol or p-phenylenediamine), and Ar ³ is a 4,4′-biphenylylene group. (Repeating unit derived from 4,4′-dihydroxybiphenyl, 4-amino-4′-hydroxybiphenyl or 4,4′-diaminobiphenyl) is preferred.

The content of the repeating unit (1) is the total amount of all repeating units constituting the liquid crystal polyester (the substance of each repeating unit is obtained by dividing the mass of each repeating unit constituting the liquid crystal polyester by the formula weight of each repeating unit). The equivalent amount (mole) is obtained, and the sum of these is preferably 30 mol% or more, more preferably 30 to 80 mol%, still more preferably 30 to 60 mol%, and particularly preferably 30 to 40 mol%. Mol%.
The content of the repeating unit (2) is preferably 35 mol% or less, more preferably 10 to 35 mol%, still more preferably 20 to 35 mol%, based on the total amount of all repeating units constituting the liquid crystal polyester. Most preferably, it is 30-35 mol%.
The content of the repeating unit (3) is preferably 35 mol% or less, more preferably 10 to 35 mol%, still more preferably 20 to 35 mol%, based on the total amount of all repeating units constituting the liquid crystal polyester. Most preferably, it is 30-35 mol%.
As the content of the repeating unit (1) is increased, the heat resistance, strength and rigidity are likely to be improved. However, if the content is too large, the solubility in a solvent is likely to be lowered.

  The ratio between the content of the repeating unit (2) and the content of the repeating unit (3) is expressed as [content of repeating unit (2)] / [content of repeating unit (3)] (mol / mol). The ratio is preferably 0.9 / 1 to 1 / 0.9, more preferably 0.95 / 1 to 1 / 0.95, and still more preferably 0.98 / 1 to 1 / 0.98.

  In addition, liquid crystalline polyester may have 2 or more types of repeating units (1)-(3) each independently. The liquid crystal polyester may have a repeating unit other than the repeating units (1) to (3), and the content thereof is preferably 10 with respect to the total amount of all repeating units constituting the liquid crystal polyester. The mol% or less, more preferably 5 mol% or less.

  The liquid crystalline polyester has a repeating unit (3) in which X and / or Y is an imino group (—NH—), that is, a repeating unit derived from a predetermined aromatic hydroxylamine and / or an aromatic diamine. It is preferable that the repeating unit (3) has only those in which X and / or Y is an imino group. By doing in this way, liquid crystalline polyester becomes the thing which was more excellent in the solubility with respect to a solvent.

  The liquid crystal polyester is preferably produced by melt polymerization of raw material monomers corresponding to the repeating units constituting the liquid crystal polyester and solid-phase polymerization of the obtained polymer (prepolymer). Thereby, high molecular weight liquid crystal polyester having high heat resistance, strength and rigidity can be produced with good operability. Melt polymerization may be carried out in the presence of a catalyst. Examples of the catalyst in this case include metals such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide. Compounds, nitrogen-containing heterocyclic compounds such as 4- (dimethylamino) pyridine, 1-methylimidazole and the like can be mentioned, and nitrogen-containing heterocyclic compounds are preferably used.

  The liquid crystal polyester has a flow initiation temperature of preferably 250 ° C. or higher, more preferably 250 ° C. to 350 ° C., and still more preferably 260 ° C. to 330 ° C. As the flow start temperature is higher, the heat resistance, strength and rigidity are more likely to be improved. However, if the flow start temperature is too high, the solubility in a solvent tends to be low, and the viscosity of the liquid composition described later tends to be high.

The flow start temperature is also called flow temperature or flow temperature, and the temperature is raised at a rate of 4 ° C./min under a load of 9.8 MPa (100 kg / cm ² ) using a capillary rheometer while liquid crystal polyester is used. Is a temperature showing a viscosity of 4800 Pa · s (48000 poise) when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm, and is a measure of the molecular weight of the liquid crystalline polyester (Naide Koide, “ “Liquid Crystal Polymer—Synthesis / Molding / Application—”, CMC Co., Ltd., June 5, 1987, p. 95).

Examples of the thermally conductive filler in the liquid composition include those having a thermal conductivity of preferably 10 W / (m · K) or more, more preferably 30 W / (m · K) or more. One or more compounds selected from the group consisting of metal nitrides and metal carbides can be exemplified.
Among them, the thermal conductive filler is preferably selected from oxides, nitrides and carbides of elements up to the seventh column of each of the II, III and IV groups of the periodic table, and specifically, beryllium oxide. , Magnesium oxide, aluminum oxide, thorium oxide, zinc oxide, silicon nitride, aluminum nitride, boron nitride, silicon carbide and the like. Aluminum oxide, aluminum nitride, boron nitride are more preferable, and boron nitride is excellent in thermal conductivity. Is particularly preferred.
The heat conductive filler is preferably in the form of powder.

  In the liquid composition, the ratio of the heat conductive filler to the total content of the liquid crystal polyester and the heat conductive filler is 50 to 80% by volume, preferably 60 to 70% by volume at room temperature such as 23 ° C. By setting it to the lower limit value or more, the insulating layer described later has sufficient thermal conductivity, and by setting the lower limit value or less, the insulating layer has sufficient strength.

  The solvent in the liquid composition may be one in which the liquid crystal polyester to be used does not dissolve (disperses), but one in which the liquid crystal polyester to be used can be dissolved is preferable. Examples that can be dissolved at a concentration of 1% by mass or more ([liquid crystal polyester] / [liquid crystal polyester + solvent] × 100) can be given.

  Examples of the solvent include halogenated hydrocarbons such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chlorobutane, chlorobenzene, and o-dichlorobenzene. Halogenated phenols such as p-chlorophenol, pentachlorophenol and pentafluorophenol; ethers such as diethyl ether, tetrahydrofuran and 1,4-dioxane; ketones such as acetone and cyclohexanone; esters such as ethyl acetate and γ-butyrolactone; Carbonates such as ethylene carbonate and propylene carbonate; amines such as triethylamine; nitrogen-containing heterocyclic aromatic compounds such as pyridine; nitriles such as acetonitrile and succinonitrile; N, N-dimethylformamide; N-dimethylacetamide, N-methylpyrrolidone (N-methyl-2-pyrrolidone) and other amide compounds (compounds having an amide bond); tetramethylurea and other urea compounds; nitromethane and nitrobenzene and other nitro compounds; dimethyl sulfoxide And sulfur compounds such as sulfolane; and phosphorus compounds such as hexamethylphosphoric acid amide and tri-n-butylphosphoric acid, and two or more of these may be used.

As the solvent, since it is low in corrosivity and easy to handle, an aprotic compound, particularly a solvent mainly comprising an aprotic compound having no halogen atom, is preferred, and the proportion of the aprotic compound in the entire solvent is: Preferably it is 50-100 mass%, More preferably, it is 70-100 mass%, More preferably, it is 90-100 mass%.
The aprotic compound is preferably N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, tetramethylurea, or γ-butyrolactone, since it easily dissolves liquid crystal polyester. N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone are more preferable.

  Moreover, as a solvent, since it is easy to melt | dissolve liquid crystalline polyester, the solvent which has a compound whose dipole moment is 3-5 as a main component is preferable, and the compound whose dipole moment occupies the whole solvent is 3-5 The ratio is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 90 to 100% by mass, and a compound having a dipole moment of 3 to 5 is used as the aprotic compound. It is preferable.

  Moreover, as a solvent, since it is easy to remove, the solvent which has as a main component the compound whose boiling point in 1 atmosphere is 220 degrees C or less is preferable, and the boiling point in 1 atmosphere which occupies the whole solvent of the compound which is 220 degrees C or less The ratio is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 90 to 100% by mass. As the aprotic compound, a compound having a boiling point of 220 ° C. or less at 1 atm. It is preferable to use it.

  In the liquid composition, the content of the liquid crystal polyester with respect to 100 parts by mass of the solvent is preferably 0.01 to 100 parts by mass. By setting it to the lower limit value or more, the viscosity of the liquid crystal polyester liquid composition does not become too low, and by setting it to the upper limit value or less, the viscosity of the liquid crystal polyester liquid composition does not become too high, and each coating is easy. Become. From the viewpoint of workability and economy, the content of the liquid crystal polyester is more preferably 1 to 50 parts by mass, and further preferably 2 to 40 parts by mass.

  The liquid composition may contain one or more other components such as a filler other than the heat conductive filler, an additive, and a resin other than the liquid crystal polyester.

  Examples of the filler include inorganic fillers such as silica, titanium oxide, zirconia, kaolin, barium titanate, strontium titanate, aluminum hydroxide, calcium carbonate, calcium phosphate; epoxy resin, benzoguanamine resin, acrylic resin, melamine resin And organic fillers such as urea resin and styrene resin.

  Examples of the additive include a coupling agent, an anti-settling agent, a heat stabilizer, a leveling agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, a flame retardant, and a colorant, and the content thereof is The amount is preferably 0 to 5 parts by mass with respect to 100 parts by mass of the liquid crystalline polyester.

  Examples of the resin other than the liquid crystal polyester include polypropylene, polyamide, polyester other than the liquid crystal polyester, thermoplastic resin such as polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether, polyether imide; phenol resin, epoxy Thermosetting resins such as resins, polyimide resins, and cyanate resins; elastomers such as copolymers of glycidyl methacrylate and polyethylene, and the content thereof is preferably 0 to 20 masses with respect to 100 parts by mass of the liquid crystalline polyester. Part.

  The liquid composition can be prepared by mixing the liquid crystal polyester, the heat conductive filler, the solvent, and other components used as necessary, all at once or in an appropriate order. Especially, it is preferable to prepare by dissolving liquid crystalline polyester in a solvent to obtain a liquid crystalline polyester solution and dispersing a heat conductive filler in the liquid crystalline polyester solution. When the filler is used as another component, it is preferable to prepare the filler by further dispersing the filler in addition to the heat conductive filler.

Application of the liquid composition onto the conductive foil 13 is preferably performed by casting. For example, a roller coating method, a dip coating method, a spray coating method, a spinner coating method, a curtain coating method, a slot coating method, a screen. Various methods such as a printing method can be adopted.
In addition, the liquid composition may be applied onto the conductive foil 13 after filtering with a filter or the like as necessary to remove fine foreign matters.

  The method for removing the solvent from the liquid composition applied on the conductive foil 13 is not particularly limited, but is preferably a method of evaporating the solvent from the viewpoint of simple operation, and any one of heating, decompression and ventilation is used alone. Or a method of evaporating by combining two or more. Among these, from the viewpoint of production efficiency and handleability, a method of evaporating by heating is preferable, and a method of evaporating while ventilating and heating is more preferable. The heating for evaporating the solvent is preferably performed at 40 to 200 ° C. for 5 minutes to 2 hours. Here, “removing the solvent” does not necessarily mean “removing all the solvent”.

  The liquid crystal polyester-containing layer 12 'thus formed preferably has a solvent content of 5 to 15% by mass, more preferably 7 to 12% by mass. By setting it to the lower limit value or more, the porosity of the liquid crystal polyester-containing layer 12 ′ after the first pressing step described later and the insulating layer 12 formed therefrom is reduced. It is excellent in the property and heat conductivity. Moreover, the shape of liquid crystal polyester content layer 12 'after a 1st press process is maintained more stably by setting it as an upper limit or less.

[First press process]
Following the drying step, in the first pressing step, the conductive foil 13 and the liquid crystal polyester-containing layer 12 ′ formed thereon are pressed (pressurized). By pressing, the amount of bubbles in the liquid crystal polyester-containing layer 12 ′ is reduced and the porosity is reduced.
In the first pressing step, for example, as shown in FIG. 3, a sheet-like or film-like release material 9 is disposed on the liquid crystal polyester-containing layer 12 ′, and the release material 9 and the conductive foil are indicated by arrows. It can carry out by pressing the conductive foil 13 and liquid crystal polyester content layer 12 'from the any one or both sides of 13. FIG.

The material of the release material 9 may be a known material such as a polyimide resin.
The release material 9 may be removed after the press.

The pressing in the first pressing step may be performed under normal pressure or under vacuum.
The pressure at the time of pressing in the first pressing step is preferably equal to or lower than the pressure at the time of pressing in the second pressing step to be described later.

The temperature during pressing in the first pressing step is preferably 20 ° C or higher, and more preferably 30 ° C or higher.
And it is preferable that the press in a 1st press process is a heat press, and it is preferable that the temperature at the time of a heating is 60-250 degreeC, and it is more preferable that it is 100-250 degreeC. By heat-pressing, the porosity of the liquid crystal polyester-containing layer 12 ′ is reduced, and the insulating layer 12 and the metal base substrate 1 are more excellent in voltage resistance and thermal conductivity.

What is necessary is just to set the press time in a 1st press process in consideration of the presence or absence of a heating, the pressure at the time of a press, etc.
For example, the heating press is preferably performed at 60 to 250 ° C for 5 to 30 minutes, and more preferably at 100 to 250 ° C for 10 to 20 minutes.

[Heat treatment process]
Following the first pressing step, in the heat treatment step, the pressed liquid crystal polyester-containing layer 12 ′ is heat-treated, and as shown in FIG. 2B, an insulating layer (liquid crystal polyester film) is formed on the conductive foil 13. 12 is formed. By the heat treatment, the liquid crystalline polyester is further increased in molecular weight and heat resistance is improved. Moreover, since the porosity of liquid crystal polyester content layer 12 'after a 1st press process is small, the porosity of the formed insulating layer 12 also becomes small and a withstand voltage property improves.

The heat treatment is preferably performed in an atmosphere of an inert gas such as nitrogen gas.
The heat treatment is preferably performed at 200 to 400 ° C. for 30 minutes to 5 hours.

  Although the thickness of the insulating layer 12 after the heat treatment can be arbitrarily adjusted according to the purpose, it is preferably 10 to 500 μm from the viewpoint of film formability and mechanical properties, and further from the viewpoint of suppressing thermal resistance. , 200 μm or less is preferable.

The porosity of the insulating layer 12 is preferably 30% or less. In particular, when the porosity is 20% or less, the voltage resistance and thermal conductivity of the insulating layer 12 are remarkably excellent.
The porosity (%) of the insulating layer is calculated by multiplying the value obtained by dividing the actually measured density of the insulating layer by the theoretical density of the insulating layer by 100.

  The insulating layer 12 has small anisotropy in the longitudinal direction (the casting direction of the liquid composition) and the lateral direction (the direction perpendicular to the casting direction of the liquid composition), and is excellent in mechanical strength. In addition, the liquid crystal polyester has excellent high-frequency characteristics, low water absorption, and other performances.

[Second press process]
Following the heat treatment step, in the second pressing step, the metal layer 11 is provided on the insulating layer 12 by hot pressing. The metal plate which comprises the metal layer 11 is fixed on the insulating layer 12 by fusion | melting by a hot press, and as shown in FIG.2 (c), the metal base substrate 1 is obtained. Moreover, by heat-pressing, the holes of the insulating layer 12 are further reduced, and the voltage resistance is improved.

The metal layer 11 is the same as the metal layer (metal base) in the conventional electronic circuit board, and the material thereof is copper, aluminum, silver, an alloy containing one or more metals selected from these, or stainless steel. Preferably there is.
The thickness of the metal layer 11 is preferably 18 to 5000 μm.
The metal layer 11 is not necessarily flat and may be bent such as having a curved surface.

The heat press in the second pressing step is preferably performed under vacuum or in an inert gas atmosphere in order to prevent an oxidation reaction.
When heat-pressing under vacuum, it is preferable to carry out under reduced pressure, such as 2 KPa or less.
When heat-pressing in an inert gas atmosphere, an inert gas such as nitrogen gas may be used.

The pressure during the hot pressing in the second pressing step is preferably 50 to 150 kg / cm ² .
The temperature during the hot pressing in the second pressing step is preferably 260 to 360 ° C.
And the time of the heat press in a 2nd press process should just be set in consideration of the pressure at the time of a press.
The heating press in the second pressing step is preferably performed, for example, at 260 to 360 ° C. for 10 to 40 minutes at 50 to 150 kg / cm ² .

  In the metal base substrate 1, a circuit wiring pattern can be formed by patterning the conductive foil 13 into a desired shape by etching or the like. Then, electronic components are mounted on the metal base substrate 1 using this wiring pattern.

  The metal base substrate obtained by the above-described manufacturing method has a low porosity of the liquid crystal polyester-containing layer after the first pressing step, and then the porosity of the formed insulating layer also decreases. Excellent voltage and thermal conductivity. Specifically, for example, a metal base substrate having a withstand voltage value of 2.5 kV or more and a thermal conductivity of 7.5 or more can be suitably obtained. In this way, the press process is performed twice, and the first press process for the purpose of mainly reducing the porosity of the insulating layer, and the second press process for the purpose of providing a metal layer, However, by carrying out at a low pressing pressure, it is possible to produce a metal base substrate that is excellent in voltage resistance and thermal conductivity, and has high reliability and heat dissipation without reducing productivity. Such metal base substrate stabilizes the operation of these electronic components even when electronic components such as power transistors and hybrid ICs are mounted with high density, by dissipating (dissipating heat) through the insulating layer and metal layer. Can be made.

<Method for producing liquid crystal polyester film>
The method for producing a liquid crystal polyester film according to the present invention is a method for producing a liquid crystal polyester film containing a heat conductive filler, comprising liquid crystal polyester, a heat conductive filler and a solvent, and the liquid crystal polyester and the heat conductive filler. The liquid crystalline polyester liquid composition in which the proportion of the heat conductive filler in the total content of the liquid is 50 to 80% by volume is applied onto the first heat-resistant substrate, and the solvent is removed from the applied liquid composition. A first step of pressing the first heat-resistant substrate and the liquid crystal polyester-containing layer, and a heat treatment of the liquid crystal polyester-containing layer after the first press step. A heat treatment step of forming a liquid crystal polyester film on the first heat-resistant substrate, and a heat press, on the liquid crystal polyester film A second pressing step of providing a second heat-resistant base member, the first and by removing the second heat-resistant base member, and having a film step to obtain a liquid crystal polyester film, a. A liquid crystal polyester film excellent in thermal conductivity and voltage resistance can be obtained by performing the pressing step twice and reducing the pressure in each pressing step.

  The method for producing a liquid crystal polyester film according to the present invention uses a first heat-resistant substrate instead of the conductive foil, and a second heat-resistant substrate instead of the metal layer (metal plate). Except having the process of removing the 1st and 2nd heat resistant base material, it is the same as that of the manufacturing method of said metal base substrate.

As the first heat-resistant substrate, not only the metal foil in the method for producing a metal base substrate, but also any material can be used as long as it has heat resistance suitable for a heating press. For example, the material is not limited to metal, and may be resin or the like. The thickness may be the same as that of the metal foil or may be different from that of the metal foil, as long as it can be removed in the film forming step, and is preferably 5 to 500 μm.
As the second heat-resistant substrate, not only the metal layer in the method for producing a metal base substrate, but also any material having heat resistance suitable for heating press can be used. May be the same.

In the film forming step, the first and second heat-resistant substrates may be removed by a method suitable for the material and the like.
For example, when using a metal or metal alloy as the first and second heat-resistant substrates, including the case where the metal base substrate obtained by the above manufacturing method is used, The second heat resistant substrate may be removed by etching. Moreover, what is necessary is just to remove the 1st and 2nd heat resistant base materials which consist of resin, such as a polyimide, by peeling.

  The liquid crystal polyester film is suitable as a heat dissipation film because it is excellent in thermal conductivity like the insulating layer in the metal base substrate. Further, since the anisotropy in the vertical and horizontal directions is small, the mechanical strength is excellent, and the performance such as high frequency characteristics and low water absorption is excellent, it is suitable as various insulating films for electronic parts. Moreover, you may use it with a film form or a sheet form, and may use it as other shapes, such as a container shape.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples. In addition, the flow start temperature of liquid crystalline polyester and the viscosity of liquid crystalline polyester liquid composition were measured by the following methods, respectively.

(Measurement of flow start temperature of liquid crystal polyester)
Using a flow tester (manufactured by Shimadzu Corp., CFT-500 type), about 2 g of liquid crystalline polyester was filled into a cylinder equipped with a die having a nozzle having an inner diameter of 1 mm and a length of 10 mm, and 9.8 MPa (100 kg / cm ^2). The liquid crystal polyester was melted while being heated at a rate of 4 ° C./min under a load of 4), extruded from a nozzle, and a temperature showing a viscosity of 4800 Pa · s (48000 poise) was measured.

(Measurement of viscosity of liquid crystal polyester liquid composition)
Liquid crystal polyester (28.2 parts by mass) is added to N, N-dimethylacetamide (DMAc) (100 parts by mass), heated at 100 ° C. for 2 hours, and liquid crystal polyester liquid composition for test (liquid crystal polyester solution) The viscosity of the liquid crystal polyester liquid composition was measured at 23 ° C. using a B type viscometer “TVL-20 type” (rotor No. 21, rotation speed 5 rpm) manufactured by Toki Sangyo Co., Ltd.

<Manufacture of liquid crystal polyester liquid composition>
[Production Example 1]
(Manufacture of liquid crystal polyester)
A reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser was charged with 6-hydroxy-2-naphthoic acid (1976 g, 10.5 mol) and 4-hydroxyacetanilide (1474 g, 9. 75 mol), isophthalic acid (1620 g, 9.75 mol) and acetic anhydride (2374 g, 23.25 mol) were charged, and the gas in the reactor was sufficiently replaced with nitrogen gas, followed by stirring under a nitrogen gas stream. The temperature was raised from room temperature to 150 ° C. over 15 minutes, and this temperature (150 ° C.) was maintained and refluxed for 3 hours.
Next, while distilling off the by-product acetic acid to be distilled off and unreacted acetic anhydride, the temperature was raised to 300 ° C. over 170 minutes, and the time at which an increase in torque was observed was regarded as the reaction end time. The contents were removed. The contents were cooled to room temperature, and the resulting solid was pulverized with a pulverizer to obtain a liquid crystal polyester powder having a relatively low molecular weight. The flow starting temperature of this liquid crystal polyester powder was 235 ° C. This liquid crystal polyester powder was subjected to solid phase polymerization by heat treatment at 223 ° C. for 3 hours in a nitrogen gas atmosphere. The flow starting temperature of the liquid crystal polyester after solid phase polymerization was 270 ° C.

(Manufacture of liquid crystal polyester liquid composition)
The obtained liquid crystal polyester (2200 g) was added to N, N-dimethylacetamide (DMAc) (7800 g) and heated at 100 ° C. for 2 hours to obtain a liquid crystal polyester solution. The viscosity of this liquid crystal polyester solution was 320 cP. In this liquid crystal polyester solution, scale aggregated boron nitride powder (“HP40P” manufactured by Mizushima Alloy Iron Co., Ltd.) as a heat conductive filler was dispersed to obtain a liquid crystal polyester liquid composition. At this time, the ratio of the heat conductive filler to the total content of the liquid crystalline polyester and the heat conductive filler was 57% by volume at 23 ° C.

<Manufacture of metal base substrate and liquid crystal polyester film>
[Example 1]
A metal base substrate and a liquid crystal polyester film were manufactured by the manufacturing method described with reference to FIG. More specifically, it is as follows.
The liquid crystal polyester liquid composition obtained in Production Example 1 was stirred with a centrifugal defoamer for 5 minutes, and then coated on a copper foil having a thickness of 70 μm so as to have a thickness of 380 μm. And this was dried for 30 minutes, ventilating at 100 degreeC, and the solvent content of the formed liquid crystal polyester content layer was 9 mass% (drying process).
Next, a polyimide film (manufactured by Toray DuPont, thickness 50 μm) is placed on the surface of the liquid crystal polyester-containing layer as a release film, and the copper foil and the liquid crystal polyester-containing layer are applied at a pressure of 100 kg from both the copper foil side and the polyimide film side. / Cm ² , and heated and pressed at a temperature of 100 ° C. for 20 minutes (first pressing step).
Next, the polyimide film is peeled from the obtained laminate, and the liquid crystal polyester-containing layer after heat pressing is heated at 300 ° C. for 3 hours in a nitrogen gas atmosphere, and an insulating layer is formed on the copper foil with a thickness of 100 μm. A liquid crystal polyester film was formed (heat treatment step).
Next, an aluminum alloy plate having a thermal conductivity of 140 W / (m · K) and a thickness of 2.0 mm is disposed on the liquid crystal polyester film, and the pressure is 100 kg from both the copper foil side and the aluminum alloy plate side. An aluminum alloy plate was provided on the liquid crystal polyester film by heat-pressing for 20 minutes at / cm ² and a temperature of 340 ° C. (second pressing step).
As described above, a metal base substrate provided with an aluminum alloy plate, a liquid crystal polyester film, and a copper foil in this order was manufactured.
Next, from the obtained metal base substrate, the copper foil and the aluminum alloy plate are removed by etching using a ferric chloride (iron (III) chloride) aqueous solution (film forming step), and a liquid crystal polyester film Manufactured.

[Example 2]
A metal base substrate and a liquid crystal polyester film were produced in the same manner as in Example 1 except that the temperature in the first pressing step was changed to 220 ° C. instead of 100 ° C.

[Example 3]
By changing the drying time in the drying step to 1 hour instead of 30 minutes, the solvent content of the liquid crystal polyester-containing layer is set to 5% by mass, and the temperature in the first pressing step is changed to 100 ° C. and 220 ° C. A metal base substrate and a liquid crystal polyester film were produced in the same manner as in Example 1 except that.

[Example 4]
A metal base substrate and a liquid crystal polyester film were produced in the same manner as in Example 1 except that the temperature in the first pressing step was 40 ° C. instead of 100 ° C.

[Comparative Example 1]
A metal base substrate and a liquid crystal polyester film were produced in the same manner as in Example 1 except that the first pressing step was not performed.

[Comparative Example 2]
The metal base substrate and the liquid crystal polyester film were prepared in the same manner as in Example 1 except that the first pressing step was not performed and the pressure in the second pressing step was changed to 200 kg / cm ² instead of 100 kg / cm ^2. Manufactured.

<Measurement of solvent content of liquid crystal polyester-containing layer>
The solvent content of the liquid crystal polyester-containing layer after the drying step in each of the above Examples and Comparative Examples was measured by the following method. That is, the liquid crystal polyester-containing layer formed in the drying step was peeled off from the copper foil, dried under reduced pressure at 160 ° C. for 5 hours, and then the solvent content was calculated from the weight loss rate before and after drying. The results are shown in Table 1.

<Calculation of porosity of insulating layer>
The porosity of the insulating layer (liquid crystal polyester film) after completion of the heat treatment step in each of the above Examples and Comparative Examples was calculated from the following formula. The results are shown in Table 1.
Porosity of insulating layer (%) = [actual density of insulating layer] ÷ [theoretical density of insulating layer] × 100
The measured density of the insulating layer is the Archimedes method for the insulating layer obtained by removing the copper foil by etching with a ferric chloride (iron (III) chloride) aqueous solution from the laminate obtained in the heat treatment step. It was measured by.

<Characteristic evaluation of liquid crystal polyester film (insulating layer)>
About the liquid crystal polyester film (insulating layer) obtained by each said Example and comparative example, the characteristic was evaluated by the following method. The results are shown in Table 1. In Table 1, “LCP” means a liquid crystal polyester film.
(Withstand voltage value)
With the test piece of the metal base substrate immersed in insulating oil, an AC voltage was applied between the copper foil and the aluminum alloy plate at room temperature, and the dielectric breakdown voltage at this time was defined as a withstand voltage value (kV).
(Thermal conductivity)
About the liquid crystalline polyester film after removing copper foil and an aluminum alloy plate, the thermal diffusivity, the constant pressure specific heat capacity, and the density were measured, and thermal conductivity was computed from the following formula using these measured values.
Thermal conductivity = thermal diffusivity × specific heat × density The thermal diffusivity is obtained by cutting a liquid crystal polyester film into a size of 10 mm × 10 mm × 0.1 mm to obtain a test piece. ai-Phase Mobile ”) at room temperature.
The specific heat was measured by comparison with a sapphire standard using a differential scanning calorimeter (DSC).
The density was measured by the Archimedes method.

As is clear from the above results, in Examples 1 to 4, the metal base substrate (liquid crystal polyester film) was obtained by performing the first and second pressing steps, despite the low pressing pressure in these steps. It was excellent in both voltage resistance and thermal conductivity. In particular, in Examples 1 to 3 where the heating temperature in the first pressing step was high, the effect was high. And Example 2 is more excellent in withstand voltage and thermal conductivity than Example 1, and this is removal of bubbles from the liquid crystal polyester-containing layer due to higher heating temperature in the first pressing step. This is presumed to be because the porosity was reduced and the porosity became smaller. In addition, Example 1 is more excellent in voltage resistance than Example 3, and this is because the liquid crystal polyester-containing layer has an appropriate flexibility due to the high solvent content of the liquid crystal polyester-containing layer immediately after the drying step. This is presumably because the removal of bubbles was promoted and the porosity became smaller.
In contrast, in Comparative Example 1, the metal base substrate (liquid crystal polyester film) was inferior in both voltage resistance and thermal conductivity. It was speculated that this was because the porosity of the insulating layer (liquid crystal polyester film) after the heat treatment step was increased because the first pressing step was not performed.
Moreover, in the comparative example 2, although the porosity of the insulating layer (liquid crystal polyester film) after the heat treatment process was high because the first press process was not performed, the press pressure in the second press process was increased. As a result, the metal base substrate (liquid crystal polyester film) was excellent in both voltage resistance and thermal conductivity. However, since this method has a high press pressure, it is difficult to apply it to a large-scale manufacturing apparatus, resulting in low productivity.

  INDUSTRIAL APPLICATION This invention can be utilized for manufacture of the thermal radiation material for diffusing the heat | fever which generate | occur | produced in the electronic component, the thermal radiation film for electronic components, and an insulating film.

  DESCRIPTION OF SYMBOLS 1 ... Metal base substrate, 9 ... Release material, 11 ... Metal layer, 12 ... Insulating layer (liquid crystal polyester film), 12 '... Liquid crystal polyester content layer, 13 ... Conductive foil

Claims (8)

A method for producing a metal base substrate comprising an insulating layer containing liquid crystalline polyester and a heat conductive filler, a conductive foil and a metal layer,
A liquid crystal polyester liquid composition containing the liquid crystal polyester, a heat conductive filler and a solvent, wherein the ratio of the heat conductive filler to the total content of the liquid crystal polyester and the heat conductive filler is 50 to 80% by volume, A drying step of applying on the conductive foil and removing the solvent from the applied liquid composition to form a liquid crystal polyester-containing layer;
A first pressing step of pressing the conductive foil and the liquid crystal polyester-containing layer;
Heat-treating the liquid crystal polyester-containing layer after the first pressing step to form an insulating layer on the conductive foil; and
A second pressing step of providing a metal layer on the insulating layer by a heating press;
A method for producing a metal base substrate, comprising:   The method for producing a metal base substrate according to claim 1, wherein the press in the first pressing step is a heat press at 60 to 250 ° C.   The method for producing a metal base substrate according to claim 1 or 2, wherein the liquid crystal polyester-containing layer has a solvent content of 5 to 15 mass%.   The method for producing a metal base substrate according to any one of claims 1 to 3, wherein the thermally conductive filler is at least one selected from the group consisting of aluminum oxide, aluminum nitride, and boron nitride. . The said liquid crystalline polyester has a repeating unit represented by following General formula (1), (2) and (3), The manufacture of the metal base substrate as described in any one of Claims 1-4 characterized by the above-mentioned. Method.
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
(3) ^-X-Ar 3 -Y-
(In the formula, Ar ¹ is a phenylene group, a naphthylene group or a biphenylylene group; Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylylene group or a group represented by the following general formula (4): Yes; X and Y are each independently an oxygen atom or imino group; one or more hydrogen atoms in Ar ¹ , Ar ² and Ar ³ are each independently substituted with a halogen atom, an alkyl group or an aryl group May be.)
(4) -Ar ⁴ -Z-Ar ^5-
(In the formula, Ar ⁴ and Ar ⁵ are each independently a phenylene group or a naphthylene group; Z is an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)   The liquid crystalline polyester has a repeating unit represented by the general formula (1) of 30 to 80 mol% and a repeating unit represented by the general formula (2) based on the total amount of all repeating units constituting the liquid crystalline polyester. The method for producing a metal base substrate according to claim 5, wherein 10 to 35 mol% and 10 to 35 mol% of the repeating unit represented by the general formula (3) are contained.   In the said General formula (3), X and / or Y are imino groups, The manufacturing method of the metal base substrate of Claim 5 or 6 characterized by the above-mentioned. A method for producing a liquid crystal polyester film containing a heat conductive filler,
A liquid crystal polyester liquid composition containing liquid crystal polyester, a heat conductive filler and a solvent, wherein the ratio of the heat conductive filler to the total content of the liquid crystal polyester and the heat conductive filler is 50 to 80% by volume, Coating on the heat-resistant substrate, and removing the solvent from the applied liquid composition to form a liquid crystal polyester-containing layer,
A first pressing step of pressing the first heat-resistant substrate and the liquid crystal polyester-containing layer;
Heat-treating the liquid crystal polyester-containing layer after the first pressing step to form a liquid crystal polyester film on the first heat-resistant substrate; and
A second press step of providing a second heat-resistant substrate on the liquid crystal polyester film by a heating press;
Removing the first and second heat-resistant substrates to obtain a liquid crystal polyester film; and
A method for producing a liquid crystal polyester film, comprising:

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