JP2014028449A - Laminate and metal base circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate which provides a metal base circuit board having an insulating layer which does not thermally expand easily and has excellent voltage resistance.SOLUTION: The laminate includes a metal plate, an insulating layer provided on the metal plate and containing a liquid crystalline polyester and an inorganic filler, and a metal foil provided on the insulating layer. The inorganic filler contains aluminum oxide and talc, and the aspect ratio of the aluminum oxide is 2 or higher. The ratio of the liquid crystalline polyester in the insulating layer is preferably 35-60 vol.%, and the ratio of the inorganic filler in the insulating layer is preferably 40-65 vol.%.

Description

  The present invention relates to a laminated board and a metal base circuit board using the laminated board.

  In recent years, with the miniaturization, high performance and high power of electric / electronic devices, circuit boards are required to easily dissipate heat generated from mounted elements, that is, to have excellent heat dissipation. . The circuit board is also required to have excellent heat resistance and voltage resistance. As a circuit board capable of meeting these requirements, a metal base circuit board having a metal plate, an insulating layer provided thereon, and a circuit pattern provided thereon has been studied. This metal base circuit board is obtained by patterning a metal foil from a laminate having a metal plate, an insulating layer provided thereon, and a metal foil provided thereon. And since the said insulating layer is excellent in heat conductivity and heat resistance, what contains liquid crystalline polyester and an inorganic filler is examined. For example, Patent Documents 1 to 7 describe that the inorganic filler uses a material having high thermal conductivity such as aluminum oxide, and describes that a spherical material is used as the aluminum oxide. Yes.

International Publication No. 2010/117033 JP 2011-32316 A JP 2011-77270 A JP 2011-181833 A JP 2011-219749 A JP 2011-249606 A JP 2012-4323 A

  In the conventional metal base substrate, the insulating layer may be easily thermally expanded. For this reason, for example, in the manufacture of a metal base circuit board, first, a laminated intermediate body of a metal foil and an insulating layer is manufactured, and then this laminated intermediate body is bonded to a metal plate, and the metal foil, the insulating layer, and the metal When producing a laminated board with a plate and then patterning the metal foil of this laminated board, the laminated intermediate is warped by heat during the production of the laminated intermediate or during bonding with the metal plate. It may be easy. In addition, the conventional metal base circuit board may not have sufficient voltage resistance of the insulating layer. SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated board that provides a metal base circuit board having an insulating layer that is hardly thermally expanded and has excellent voltage resistance.

  In order to achieve the above object, the present invention provides a laminate comprising a metal plate, an insulating layer provided on the metal plate and containing liquid crystal polyester and an inorganic filler, and a metal foil provided on the insulating layer. And the said inorganic filler contains aluminum oxide and talc, and the laminated board whose aspect ratio of the said aluminum oxide is 2 or more is provided. Moreover, according to this invention, the metal base circuit board formed by patterning the said metal foil of the said laminated board is also provided.

  The laminated board of the present invention has an insulating layer that is difficult to thermally expand and has excellent voltage resistance, and is a metal that has an insulating layer that is difficult to thermally expand and has excellent voltage resistance by patterning the metal foil. A base circuit board can be obtained.

  The laminated board of this invention has a metal plate, the insulating layer provided on it, and the metal foil provided on it.

Examples of the material of the metal plate include aluminum, iron, and copper, and may be an alloy such as an aluminum alloy or stainless steel. The metal plate may contain a nonmetal such as carbon, and may contain, for example, aluminum combined with carbon. The metal plate preferably has a high thermal conductivity, and the thermal conductivity is preferably 60 W · m ⁻¹ · K ⁻¹ or more.

  The thickness of the metal plate is usually 0.2 to 5 mm. The metal plate may have flexibility or may not have flexibility. The metal plate may have a single layer structure or a multilayer structure.

  The insulating layer is provided on the metal plate and includes liquid crystal polyester and an inorganic filler.

  The liquid crystal polyester plays a role as a binder for bonding the inorganic fillers, a role as an adhesive for bonding the metal plate and the metal foil, and a role for flattening the surface of the insulating layer. Liquid crystalline polyester is an electrically insulating material and has a higher specific resistance than many other resins.

  The liquid crystalline polyester is a liquid crystalline polyester that exhibits 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.

  A typical example of the liquid crystal polyester is polymerization (polycondensation) of 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. At least one compound selected from the group consisting of aromatic dicarboxylic acids and aromatic diols, aromatic hydroxyamines and aromatic diamines, And those obtained by polymerizing a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid. 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 formula (1) (hereinafter sometimes referred to as “repeating unit (1)”), and the repeating unit (1) and the following formula (2) A repeating unit represented (hereinafter sometimes referred to as “repeating unit (2)”) and a repeating unit represented by the following formula (3) (hereinafter sometimes referred to as “repeating unit (3)”). It is more preferable to have.

(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-

(Ar ¹ represents a phenylene group, a naphthylene group, or a biphenylylene group. Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4). X and Y are each independently a hydrogen atom in the group represented by .Ar ^1, Ar ² or Ar ³ representing an oxygen atom or an imino group (-NH-) are each independently a halogen atom, an alkyl group Alternatively, it may be substituted with an aryl group.)

(4) -Ar ⁴ -Z-Ar ^5-

(Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents 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, s-butyl group, t-butyl group, n-hexyl group, 2-ethylhexyl group, An n-octyl group and n-decyl group are mentioned, The carbon number is 1-10 normally. 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 number of carbon atoms is usually 6 to 20. . When the hydrogen atom is substituted with these groups, the number is usually 2 or less for each group represented by Ar ¹ , Ar ² or Ar ³ , and preferably 1 It is as follows.

  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 the number of carbon atoms is usually 1 to 10.

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

The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (2), Ar ² is a p-phenylene group (repeating unit derived from terephthalic acid), Ar ² is an m-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 ether- 4,4′-dicarboxylic acid-derived repeating units) are preferred.

The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine. As the repeating unit (3), those in which Ar ³ is a p-phenylene group (repeating units derived from hydroquinone, p-aminophenol or p-phenylenediamine) are preferred.

  The content of the repeating unit (1) is the total amount of all repeating units (the mass equivalent amount of each repeating unit (moles by dividing the mass of each repeating unit constituting the liquid crystal polyester by the formula amount of each repeating unit). ) And the total value thereof) is usually 30 mol% or more, preferably 30 to 80 mol%, more preferably 30 to 60 mol%, still more preferably 30 to 40 mol%. The content of the repeating unit (2) is usually 35 mol% or less, preferably 10 to 35 mol%, more preferably 20 to 35 mol%, still more preferably 30 to 35 mol, based on the total amount of all repeating units. %. The content of the repeating unit (3) is usually 35 mol% or less, preferably 10 to 35 mol%, more preferably 20 to 35 mol%, still more preferably 30 to 35 mol, based on the total amount of all repeating units. %. 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 usually 0.9 / 1 to 1 / 0.9, preferably 0.95 / 1 to 1 / 0.95, and 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. Further, the liquid crystalline polyester may have a repeating unit other than the repeating units (1) to (3), but the content thereof is usually 10 mol% or less with respect to the total amount of all repeating units, preferably 5 mol% or less.

  The liquid crystalline polyester has a repeating unit (3) in which X and / or Y is an imino group, that is, a repeating unit derived from a predetermined aromatic hydroxylamine and / or a repeating unit derived from an aromatic diamine. It is preferable that it has a solubility in a solvent, and it is more preferable that the repeating unit (3) has only those in which X and / or Y is an imino group.

  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 this catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide, And nitrogen-containing heterocyclic compounds such as 4- (dimethylamino) pyridine and 1-methylimidazole, and nitrogen-containing heterocyclic compounds are preferably used.

  The liquid polyester has a flow initiation temperature of usually 250 ° C. or higher, preferably 250 ° C. to 350 ° C., 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 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 the liquid crystalline 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).

  The proportion of the liquid crystal polyester in the insulating layer is preferably 35 to 60% by volume, more preferably 40 to 55% by volume. If this ratio is too small, the adhesiveness between the inorganic fillers may be reduced, the adhesion between the insulating layer and the metal plate or the metal foil may be reduced, or the surface flatness of the insulating layer may be reduced. On the other hand, if the ratio is increased too much, the voltage resistance of the laminated plate is lowered or the heat dissipation of the laminated plate is lowered.

  The inorganic filler includes aluminum oxide and talc.

  Aluminum oxide has an aspect ratio of 2 or more, preferably 3 or more, and a scale-like or other plate-like one is used. As the aspect ratio of aluminum oxide is larger, the insulating layer is less likely to thermally expand. Moreover, the volume average particle diameter of aluminum oxide is 1-30 micrometers normally, Preferably it is 1-10 micrometers, More preferably, it is 3-5 micrometers.

  Talc preferably has an aspect ratio of 5 or more, and, like aluminum oxide, flaky or other plate-like ones are used. As the aspect ratio of talc is larger, the insulating layer is less likely to thermally expand. Moreover, the volume average particle diameter of talc is 1-30 micrometers normally, Preferably it is 3-15 micrometers, More preferably, it is 5-12 micrometers.

  Here, the aspect ratio of the inorganic filler is the ratio of the volume average particle diameter to the number average thickness (minimum diameter) (volume average particle diameter / number average thickness), and the number average thickness is a scanning electron microscope. It is measured by observation, and the volume average particle diameter is measured by a laser diffraction scattering method.

  As at least a part of the inorganic filler, a surface-treated one may be used in order to improve the adhesion to the liquid crystal polyester and the dispersibility in the liquid composition described later. Examples of surface treatment agents that can be used for this surface treatment include silane coupling agents, titanium coupling agents, aluminum coupling agents, zirconium coupling agents, long chain fatty acids, isocyanate compounds, and epoxy groups and methoxysilyl groups. And polymers having an amino group or a hydroxyl group.

  The proportion of the inorganic filler in the insulating layer is preferably 40 to 65% by volume, more preferably 45 to 60% by volume. If this ratio is too small, the thermal conductivity of the insulating layer decreases. On the other hand, if this ratio is too large, the adhesiveness between the inorganic fillers decreases, the adhesion between the insulating layer and the metal plate or the metal foil decreases, or the voltage resistance of the laminated plate decreases.

  The proportion of aluminum oxide in the inorganic filler is preferably 70 to 95% by volume, and the proportion of talc in the inorganic filler is preferably 5 to 30% by volume. If the proportion of aluminum oxide is made too small or the proportion of talc is made too large, the adhesion between the insulating layer and the metal plate or metal foil will be lowered, the proportion of aluminum oxide will be made too large, or the proportion of talc will be reduced. If it is too small, the voltage resistance of the laminate will be reduced.

  The insulating layer may contain components other than the liquid crystal polyester and the inorganic filler, for example, a resin other than the liquid crystal polyester, an organic filler, an additive, and the like. When seeds are included, the total amount is usually 0 to 10% by volume.

  Examples of resins other than liquid crystal polyester include polypropylene, polyamide, polyester other than liquid crystal polyester, thermoplastic resin other than liquid crystal polyester such as polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether, polyether imide; and Thermosetting resins, such as a phenol resin, an epoxy resin, a polyimide resin, and cyanate resin, are mentioned. Examples of the organic filler include organic fillers such as a cured epoxy resin, a crosslinked benzoguanamine resin, and a crosslinked acrylic resin. Examples of additives include leveling agents, antifoaming agents, antioxidants, ultraviolet absorbers, flame retardants, and colorants.

  In addition, the insulating layer may contain inorganic fillers other than aluminum oxide and talc, but the proportion of the inorganic filler in the inorganic filler is a total of 0 to 10 in general when multiple types are included. % By volume. Examples of inorganic fillers other than aluminum oxide and talc include magnesium oxide, beryllium oxide, zinc oxide, aluminum nitride, and boron nitride.

  The metal foil is provided on the insulating layer and faces the metal plate with the insulating layer interposed therebetween. Examples of the metal foil material include copper and aluminum, and may be an alloy. The thickness of the metal foil is usually 10 to 500 μm.

  The production of the laminated board of the present invention is as follows. (A): First, a laminated intermediate of a metal foil and an insulating layer is produced, and then the laminated intermediate is used as a bonding surface with the insulating layer surface as a bonding surface. (B): First, a laminated intermediate of a metal plate and an insulating layer is manufactured, and then this laminated intermediate is used with its insulating layer surface as a bonding surface. (C): First, an insulating film to be an insulating layer is manufactured, and then the insulating film is sandwiched between the metal foil and the metal plate. You may carry out by bonding together by thermocompression bonding.

  The insulating layer is formed by applying a liquid composition containing a liquid crystal polyester, an inorganic filler, and other components as required, and a solvent to a support, and drying (solvent removal) the resulting coating film. It is preferable to carry out by. In that case, the laminated intermediate body of the metal foil and insulating layer in said (A) can be manufactured by using metal foil as a support body. Moreover, the laminated intermediate body of the metal plate and insulating layer in said (B) can be manufactured by using a metal plate as a support body. In addition, when a resin film other than a metal foil and a metal plate, for example, a polyester film, a polypropylene film, a fluororesin film, a nylon film, a polymethylpentene film, or the like is used as a support, an insulation formed on the support By transferring the layer from the support to the metal foil by thermocompression bonding or the like, a laminate intermediate of the metal foil and the insulating layer in (A) can be produced, and the insulating layer formed on the support is supported. By transferring from the body to the metal plate by thermocompression bonding or the like, a laminated intermediate body of the metal plate and the insulating layer in (B) can be produced, and the insulating layer formed on the support is peeled off from the support. Thus, the insulating film in (C) can be produced.

  The liquid composition is preferably prepared by dispersing the inorganic filler and, if necessary, other components in a solution obtained by dissolving liquid crystal polyester and other components, if necessary, in a solvent. The inorganic filler may be dispersed in the solution while being pulverized by a ball mill, three rolls, a centrifugal stirrer, a bead mill or the like. Further, prior to dispersing the inorganic filler in the solution, a coupling agent such as a silane coupling agent or a titanium coupling agent or an ion adsorbent may be added.

  As the solvent, a solvent that can dissolve the liquid crystal polyester to be used, specifically a solvent that can be dissolved at a concentration of 1% by mass or more at 50 ° C. ([liquid crystal polyester] / [liquid crystal polyester + solvent]) is appropriately selected. Used.

  Examples of solvents include halogenated hydrocarbons such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, o-dichlorobenzene; p-chlorophenol, pentachlorophenol, pentafluorophenol Halogenated phenols such as diethyl ether, tetrahydrofuran, 1,4-dioxane, etc .; 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 heteroaromatic compounds such as pyridine; nitriles such as acetonitrile and succinonitrile; amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone; Urea compounds such as tramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethyl sulfoxide and sulfolane; and phosphorus compounds such as hexamethylphosphoric acid amide and tri-n-butylphosphoric acid. 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%. As the aprotic compound, amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone are preferably used because the liquid crystalline polyester is easily dissolved.

  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 ratio of the compound whose dipole moment which occupies for the whole solvent is 3-5 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. Is preferred.

  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 ratio of the compound whose boiling point in 1 atmosphere in the whole solvent is 220 degrees C or less 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 boiling point of 220 ° C. or less at 1 atm is used as the aprotic compound. It is preferable.

  Content of the liquid crystal polyester in a liquid composition is 5-60 mass% normally with respect to the total amount of liquid crystal polyester and a solvent, Preferably it is 10-50 mass%, More preferably, it is 15-45 mass%, desired It adjusts suitably so that the liquid composition of this viscosity may be obtained.

  Examples of the method of applying the liquid composition to the support include a roll coating method, a bar coating method, a screen printing method, a die coater method, and a comma coater method, which may be a continuous method or a single plate method. May be.

  The coating film is preferably dried by evaporating the solvent from the coating film. When something other than metal foil and metal plate is used as the support, and the coating film formed on the support is dried and then transferred from the support to the metal foil or metal plate by thermocompression bonding, etc., part of the solvent It is preferable to carry out so that it remains in the coating film after drying. In this case, the amount of solvent in the dried coating film is preferably 1 to 25% by mass. A drying temperature is 50-180 degreeC normally, Preferably it is 80-150 degreeC.

  By heat-treating the dried coating film formed on the support or the dried coating film transferred to the metal foil or metal plate, the molecular weight and crystallinity of the liquid crystal polyester can be adjusted and bonded. An insulating layer having excellent properties and thermal conductivity can be obtained. The heat treatment is usually performed at 250 to 350 ° C., preferably 270 to 320 ° C. in an inert gas atmosphere such as nitrogen gas.

  In this way, when the laminated intermediate of the metal foil and the insulating layer is obtained, as described in (A) above, by laminating the laminated intermediate by using the insulating layer surface as a bonding surface and thermocompression bonding, The laminated board of this invention is obtained. Moreover, when the laminated intermediate body of a metal plate and an insulating layer is obtained, as above-mentioned (B), this laminated intermediate body is bonded by metal foil and thermocompression bonding etc. by using the insulating layer surface as a bonding surface. The laminated board of this invention is obtained. Moreover, when the insulating layer formed on the support is peeled from the support to obtain an insulating film, the insulating film is sandwiched between a metal foil and a metal plate as described in (C), and these are thermocompression-bonded. The laminated board of this invention is obtained by bonding together.

  The metal foil of the laminated board of the present invention is patterned to form a circuit pattern, and the metal base circuit board of the present invention is obtained by performing processing such as cutting and drilling as necessary. The patterning of the metal foil is performed, for example, by forming a mask pattern on the metal foil and removing the exposed portion of the metal foil by etching.

[Measurement of flow start temperature of liquid crystalline polyester]
Using a flow tester (“CFT-500 type” manufactured by Shimadzu Corporation), about 2 g of liquid crystalline polyester was filled into a cylinder attached 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). The liquid crystal polyester was melted while being heated at a rate of 4 ° C./min under a load of / cm ² ), extruded from a nozzle, and a temperature showing a viscosity of 4800 Pa · s (48000 P) was measured.

[Measurement of viscosity of liquid crystal polyester solution]
Using a B-type viscometer (“TVL-20” from Toki Sangyo Co., Ltd.) The measurement was performed at a rotation speed of 20 rpm using 21 rotors.

(Measurement of volume average particle diameter of inorganic filler)
100 mg of the inorganic filler was dispersed in water and measured with a laser diffraction / scattering particle size distribution analyzer (“LA-950” manufactured by Horiba, Ltd.).

[Measurement of number average thickness of inorganic filler]
The inorganic filler was observed with a scanning electron microscope at a magnification of 2000 times, 30 thicknesses randomly selected from the image were measured, and the number average value was obtained. Then, the aspect ratio was determined by dividing the volume average particle diameter by the number average thickness.

[Measurement of linear expansion coefficient of insulating layer]
A sample of 5 mm × 20 mm was cut out from the laminate, and from a thermomechanical analyzer (“TMA-120 type” manufactured by Seiko Instruments Inc.) from 30 ° C. to 250 ° C. while applying a load of 10 g in an air atmosphere. After the temperature was raised at a rate of 5 ° C./min (temperature raising step 1), the temperature was cooled from 250 ° C. to 30 ° C. at a rate of 30 ° C./min, and then the temperature was raised from 30 ° C. to 250 ° C. at a rate of 5 ° C./min. (Temperature raising step 2) In the temperature raising step 2, the linear expansion coefficient (ppm / ° C.) in the direction parallel to the plane between 50 ° C. and 100 ° C. was determined.

[Measurement of warpage rate of laminated intermediate of copper foil and insulating layer]
It measured according to JIS C6481.

[Measurement of dielectric strength of insulating layer]
The copper foil of the laminated plate was partially removed by etching to form a circular pattern of φ20 mm, and the dielectric breakdown voltage between the circular pattern and the metal plate was measured by a step-up method according to JIS C2110.

[Measurement of thermal conductivity of insulating layer]
It was calculated by the formula: thermal conductivity = thermal diffusivity × specific heat × density. The thermal diffusivity was measured at room temperature by a temperature wave thermal analysis method using “ai-Phase Mobile” manufactured by Eye Phase Co., Ltd., by cutting a 10 mm × 10 mm × 1 mm sample from the laminate. Specific heat was measured by comparison with a sapphire standard using a differential scanning calorimeter (DSC). The density was measured by the Archimedes method.

[Measurement of peel strength of copper foil]
The copper foil of the laminated plate was partially removed by etching to form a copper foil pattern having a width of 10 mm. Grasp one end of this copper foil pattern and pull the copper foil pattern from the metal plate at a speed of 50 mm / min while applying a force so that the peeled portion of the copper foil pattern is perpendicular to the main surface of the metal plate. I peeled it off. At this time, the force applied to the copper foil pattern was defined as peel strength.

Examples 1-4 and Comparative Examples 1 and 2
[Production of liquid crystalline polyester]
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas introduction tube, a thermometer and a reflux condenser, 1976 g (10.5 mol) of 6-hydroxy-2-naphthoic acid and 1474 g (9.75 mol) of 4-hydroxyacetanilide were added. ), 1620 g (9.75 mol) of isophthalic acid and 2374 g (23.25 mol) of acetic anhydride, and after replacing the gas in the reactor with nitrogen gas, the mixture was stirred at room temperature to 150 ° C. under a nitrogen gas stream. The mixture was heated up to 15 minutes and refluxed at 150 ° C. for 3 hours. Next, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150 ° C. to 300 ° C. over 2 hours and 50 minutes, held at 300 ° C. for 1 hour, and then the contents were taken out from the reactor, Cooled to room temperature. The obtained solid was pulverized with a pulverizer to obtain a powdery prepolymer. The flow initiation temperature of this prepolymer was 235 ° C. Next, the prepolymer was heated from room temperature to 223 ° C. over 6 hours under a nitrogen atmosphere and held at 223 ° C. for 3 hours to solid-phase polymerize, and then cooled to powdery liquid crystalline polyester Got. The liquid crystal polyester had a flow start temperature of 270 ° C.

[Preparation of liquid crystal polyester solution]
2200 g of liquid crystal polyester was added to 7800 g of N, N-dimethylacetamide and heated at 100 ° C. for 2 hours to obtain a liquid crystal polyester solution. The viscosity of this solution was 400 cP.

〔Aluminum oxide〕
The following were used as aluminum oxide.
Aluminum oxide (1): “AL-S43A” (volume average particle diameter of 3.5 μm, aspect ratio of 5.1 (scale-like)) manufactured by Sumitomo Chemical Co., Ltd.
Aluminum oxide (2): “AA-5” manufactured by Sumitomo Chemical Co., Ltd. (volume average particle diameter 5 μm, aspect ratio 1 (polyhedral sphere)).

〔talc〕
As talc, “K-3” (volume average particle diameter 5.5 μm, aspect ratio 8.9 (scale-like)) manufactured by Nippon Talc Co., Ltd. was used.

(Preparation of liquid composition)
Aluminum oxide and talc were added to the liquid crystal polyester solution, and the mixture was stirred for 5 minutes with a centrifugal stirring deaerator to obtain a liquid composition. The ratio between the liquid crystal polyester and the aluminum oxide and talc, from each of the specific gravity (liquid crystal polyester 1.37 g / cm ^3, aluminum oxide 3.98 g / cm ^3, aluminum oxide 2.70 g / cm ^3), Table 1 It adjusted on the mass reference | standard so that it might become the volume ratio shown in.

[Production of laminated intermediate of metal foil and insulating layer]
The liquid composition was applied to a polyester film having a thickness of 100 μm so that the thickness of the coating film was about 90 μm, and then dried at 100 ° C. for 20 minutes. The laminated intermediate of the obtained polyester film and the dried coating film was passed between a pair of hot rolls that were overlapped with a 35 μm thick copper foil and heated to 150 ° C. so that the dried coating film surface was in contact. Then, the dried coating film and the copper foil were thermocompression bonded. Next, the polyester film was peeled off, and the resulting laminated intermediate of the copper foil and the dried coating film was heat treated at 290 ° C. for 3 hours. About the obtained laminated intermediate body of copper foil and an insulating layer, the linear expansion coefficient and the curvature rate of the insulating layer were measured and shown in Table 1.

[Manufacture of laminates]
The laminated intermediate of copper foil and insulating layer is overlapped with a 1.5 mm thick metal plate (aluminum alloy plate: thermal conductivity 140 W · m ⁻¹ · K ⁻¹ ) so that the insulating layer surface is in contact The insulating layer and the metal plate were thermocompression bonded by heat treatment at 340 ° C. for 20 minutes while applying a pressure of 15 MPa. With respect to the obtained laminate, the withstand voltage of the insulating layer, the thermal conductivity of the insulating layer, and the peel strength of the copper foil were measured and shown in Table 1.

Claims (7)

  A laminated plate comprising a metal plate, an insulating layer provided on the metal plate and containing liquid crystal polyester and an inorganic filler, and a metal foil provided on the insulating layer, wherein the inorganic filler is aluminum oxide And talc, wherein the aluminum oxide has an aspect ratio of 2 or more.   The laminate according to claim 1, wherein a proportion of the liquid crystal polyester in the insulating layer is 35 to 60% by volume, and a proportion of the inorganic filler in the insulating layer is 40 to 65% by volume.   The laminate according to claim 1 or 2, wherein a ratio of the aluminum oxide in the inorganic filler is 70 to 95% by volume, and a ratio of the talc in the inorganic filler is 5 to 30% by volume.   The laminate according to any one of claims 1 to 3, wherein the talc has an aspect ratio of 5 or more. The liquid crystalline polyester is a liquid crystalline polyester having a repeating unit represented by the following formula (1), a repeating unit represented by the following formula (2), and a repeating unit represented by the following formula (3). Item 5. The laminated board according to any one of Items 1 to 4.
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(Ar ¹ represents a phenylene group, a naphthylene group, or a biphenylylene group. Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4). X And Y each independently represents an oxygen atom or an imino group, and each hydrogen atom in the group represented by Ar ¹ , Ar ² or Ar ³ is independently substituted with a halogen atom, an alkyl group or an aryl group. May be.)
(4) -Ar ⁴ -Z-Ar ^5-
(Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)   The liquid crystal polyester has a repeating unit represented by the formula (1) of 30 to 80 mol% and a repeating unit represented by the formula (2) of 10 with respect to the total amount of all repeating units constituting the liquid crystalline polyester. The laminate according to claim 5, which is a liquid crystal polyester having 35 to 35 mol% and 10 to 35 mol% of a repeating unit represented by the formula (3).   The metal base circuit board formed by patterning the said metal foil of the laminated board in any one of Claims 1-6.