JP2016117281A - Three-layer film, method of producing three-layer film, laminate and printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-layer film, a method of producing the three-layer film, a laminate and a printed circuit board.SOLUTION: The three-layer film includes a polyimide resin film and a liquid crystal polymer layer having hydroxycarboxylic acid laminated on both surface of the polyimide resin film as a mesogenic group, and a thickness of the polyimide resin film (T1) and a thickness of the liquid crystal polymer layer having hydroxycarboxylic acid as the mesogenic group satisfy the following relational expressions (a) and (b). (a)20 μm≤T1≤50 μm (b)0.3≤T2/T1≤1.5, where two T2 may each independently be same or different.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a three-layer film, a method for producing a three-layer film, a laminate, and a printed circuit board.

A laminated body in which a metal layer is provided on an insulating layer is used for a printed wiring board (printed circuit board or printed circuit board) incorporated in an electronic device such as a mobile phone, a personal computer, or a digital home appliance. As such a laminated body, the laminated body by which the layer which consists of conductors, such as metal foil, and the layer which consists of a polyimide resin film as an insulating layer were laminated | stacked is known, for example (for example, patent documents 1-2). Patent Document 3 describes a laminate in which a copper foil is employed as a metal layer and a liquid crystal polyester resin layer is laminated as an insulating layer.
A polyimide resin has water absorption and is inferior in moisture resistance. Moreover, since it is a non-thermoplastic resin, a metal foil cannot be laminated | stacked directly. Thus, for example, Patent Documents 4 to 5 describe that a laminated body of a liquid crystal polymer film and a polyimide resin is employed as the insulating layer. As a liquid crystal polymer film, the thing of patent documents 6-9 is mentioned. Since the water absorption action of the polyimide resin has a great influence on the electrical characteristics of the printed wiring board, the method of using the liquid crystal polymer film is important for improving the electrical characteristics of the printed wiring board.

JP 2006-008976 A JP 2013-032532 A JP 2007-106107 A JP 2008-290424 A JP 2008-290425 A JP 2013-189535 A JP 2004-315678 A JP 2007-238915 A JP 2013-001902 A

However, the characteristics required for the printed wiring board are further increased, and there is still room for improvement in the laminate used for the printed wiring board.
The present invention has been made in view of the above circumstances, and provides a three-layer film excellent in dimensional stability and electrical characteristics when used in a laminate for a printed wiring board, and a method for producing the three-layer film. The task is to do.

In the first aspect of the present invention, a liquid crystal polymer layer containing hydroxycarboxylic acid as a mesogen group is laminated on both sides of a polyimide resin film, and the thickness (T1) of the polyimide resin film and the hydroxycarboxylic acid are converted into a mesogen group. A three-layer film characterized in that the thickness (T2) of the liquid crystal polymer layer satisfies the following relational expressions (a) and (b) (provided that the two T2s are independent of each other and are the same) Well, it may be different.)
(A) 20 μm ≦ T1 ≦ 50 μm
(B) 0.3 ≦ T2 / T1 ≦ 1.5
In the first aspect of the present invention, the liquid crystal polymer layer having a hydroxycarboxylic acid as a mesogenic group preferably contains a structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid.

In the first aspect of the present invention, it is preferable that the liquid crystal polymer layer containing hydroxycarboxylic acid as a mesogenic group further contains the following structural units (1) and (2).
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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 second aspect of the present invention is a laminate in which the three-layer film of the first aspect is used as an insulating layer, and a metal layer is formed on at least one surface of the insulating layer.
2nd aspect of this invention WHEREIN: It is preferable that the maximum height (Rz) of the said metal layer is 0.5-2.5 micrometers.
In the second aspect of the present invention, the metal layer preferably contains copper.
A third aspect of the present invention is a printed circuit board using the laminated board of the fifth aspect.

According to a fourth aspect of the present invention, there is provided a liquid composition coating step in which a liquid composition containing a solvent and a liquid crystal polymer is coated on a polyimide resin film, and the polyimide resin film is covered with the liquid composition; A method for producing a three-layer film comprising a solvent removal step for removing the solvent therein and a heat treatment step, wherein the liquid crystal polymer is 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid. It is the manufacturing method of the three-layer film containing the derived structural unit and the following structural units (1) and (2).
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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.)

In a fifth aspect of the present invention, a liquid composition containing a solvent and a liquid crystal polymer is impregnated with a polyimide resin film, and the polyimide resin film is covered with the liquid composition, and the solvent in the liquid composition A method for producing a three-layer film, comprising a solvent removal step for removing water and a heat treatment step, wherein the liquid crystal polymer is derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid It is a manufacturing method of the three-layer film containing a unit and the following structural units (1) and (2).
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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 sixth aspect of the present invention includes a step of preparing a liquid composition containing a solvent and a liquid crystal polymer, and a polyamic acid resin liquid composition that is a precursor of a polyimide resin, and the liquid composition on a support. , The step of applying the polyamic acid resin liquid composition and the liquid composition to the three layers in this order, the solvent removing step of removing the solvent in the three-layer liquid composition, and the three-layer film forming step, And a structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid as the liquid crystal polymer, and the following structural units (1) and (2 ) Containing a three-layer film.
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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.)

  ADVANTAGE OF THE INVENTION According to this invention, when it uses for the laminated body for printed wiring boards, the three-layer film excellent in dimensional stability and an electrical property and the manufacturing method of this three-layer film can be provided.

It is a schematic diagram for demonstrating the three-layer film of this invention. It is a schematic diagram for demonstrating the laminated body using the three-layer film of this invention. It is the schematic for demonstrating the manufacturing method of the three-layer film of the 3rd aspect of this invention.

≪Three layer film≫
First, the three-layer film which is the first embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a three-layer film 20 of the present invention. In the three-layer film 20, liquid crystal polymer layers 22 a and 22 b having hydroxycarboxylic acid as a mesogen group are laminated on both surfaces of a polyimide resin film 21. In other words, the three-layer film 20 includes liquid crystal polymer layers 22a and 22b having hydroxycarboxylic acid as a mesogenic group, and a polyimide resin film 21 sandwiched between the liquid crystal polymer layers 22a and 22b.
In the three-layer film 20, the thickness (T1) of the polyimide resin film 21 and the thicknesses (T2) of the liquid crystal polymer layers 22a and 22b each having hydroxycarboxylic acid as a mesogen group are expressed by the following relational expressions (a) and (b). The two T2s (T2a and T2b in FIG. 1) are independent of each other and may be the same or different.
(A) 20 μm ≦ T1 ≦ 50 μm
(B) 0.3 ≦ T2 / T1 ≦ 1.5

[Polyimide resin film]
The polyimide resin is a condensation type polyimide obtained by polycondensation using diamines and tetracarboxylic dianhydride as starting materials. In other words, the polyimide resin is a condensation type polyimide that is a polycondensation reaction product starting from diamines and tetracarboxylic dianhydride. There is no restriction | limiting in particular as diamine, The aromatic diamine, alicyclic diamine, aliphatic diamine etc. which are normally used for the synthesis | combination of a polyimide can be used. Diamines may be used alone or in combination of two or more.
Moreover, as tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, aliphatic tetracarboxylic dianhydride and the like can be used, and are particularly limited. There is no. Tetracarboxylic dianhydride may be used alone or in combination of two or more.
Further, in at least one of the diamines and tetracarboxylic dianhydrides, at least selected from the group consisting of a fluorine group, a trifluoromethyl group, a hydroxyl group, a sulfone group, a carbonyl group, a heterocyclic ring, a long chain alkyl group, and the like. One type or a plurality of types of functional groups may be included.
In the present specification, the terms “polymerization reaction product”, “polycondensation reaction product”, “resin” and the like used for a substance in which a monomer is polymerized are structural units (also referred to as repeating units) derived from the monomer. ] "Polymerization reaction product", "polycondensation reaction product", "resin" and the like.

Among such polyimides, from the viewpoint of mechanical strength and flexibility when the polyimide resin film 21 is formed, it is preferable to use aromatic tetracarboxylic dianhydride as the tetracarboxylic dianhydride.
About diamine, aromatic diamine, alicyclic diamine, and aliphatic diamine may be used independently, and 2 or more types may be used together.
From the viewpoint of mechanical strength and flexibility when the polyimide resin film 21 is formed, the diamine is preferably an aromatic diamine.

  As the polyimide resin film, a commercially available polyimide resin (PI) film can be used. For example, Ube Industries, Ltd. PI film (U-Pyrex S, U-Pyrex R), Toray DuPont PI film (Kapton) , PI film (IF30, IF70, LV300) manufactured by SKC Kolon PI.

In the present invention, the thickness (T1) of the polyimide resin film satisfies the following formula (a).
(A) 20 μm ≦ T1 ≦ 50 μm
Here, the thickness of a polyimide resin film is a value represented by the average which measured the thickness with the contact-type thickness meter in arbitrary five places of a polyimide resin film. When measuring the thickness of the polyimide resin film, if it is difficult to directly apply a contact thickness gauge, the liquid crystal polymer layers 22a and 22b and other layers are overlaid and the same as above. Alternatively, the total thickness may be measured, and the difference may be calculated by taking the difference from the thickness of the other layer that has been superimposed (measured by the same method as described above).
In the present invention, from the viewpoint of easy availability, the thickness of the polyimide resin film is preferably 20 μm ≦ T1 ≦ 40 μm, and more preferably 20 μm ≦ T1 ≦ 30 μm.
When the thickness of the polyimide resin film is equal to or greater than the above lower limit value, it is possible to ensure the insulating properties and the posture maintaining function of the three-layer film, and when it is equal to or less than the above upper limit value, it is possible to ensure appropriate flexibility.

[Liquid Crystal Polymer]
The liquid crystal polymer used for the liquid crystal polymer layer of the three-layer film of the present invention is a liquid crystal polymer having hydroxycarboxylic acid as a mesogenic group. Typical examples include those obtained by polymerizing single or plural kinds of aromatic hydroxycarboxylic acids, single or plural kinds of aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic hydroxys. Examples include those obtained by polymerizing (polycondensation) at least one compound selected from the group consisting of amines and aromatic diamines, and those obtained by polymerizing a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid. In other words, polymerization reaction product of single or plural kinds of aromatic hydroxycarboxylic acids, single or plural kinds of aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids, aromatic diols, aromatic hydroxyamines and aromatic diamines. Examples include a polymerization reaction product (polycondensation reaction product) of at least one compound selected from the group, and a polymerization reaction product of a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid.
The mesogenic group derived from hydroxycarboxylic acid is not particularly limited, but preferably contains a structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid. Here, the mesogenic group is a molecular chain having a high rigidity along the long chain of the molecule having a rod-like or plate-like molecular shape contained in the liquid crystal molecule. The mesogenic group may be present in one or both of the main chain and the side chain of the liquid crystal polymer, but is preferably present in the main chain if high heat resistance is required.
In the present invention, the liquid crystal polymer preferably contains a structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid.

  The liquid crystal polymer preferably has a repeating unit represented by the following (1) (hereinafter sometimes referred to as “repeating unit (1)”), and is represented by the repeating unit (1) and the following formula (2). It is more preferable to have a repeating unit (hereinafter sometimes referred to as “repeating unit (2)”).

(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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 an n-decyl group are mentioned, The carbon number becomes like this. Preferably it is 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 preferably 6-20. is there.
When the hydrogen atom in the group represented by Ar ^{1 to} Ar ⁴ is substituted with these groups, the number is preferably independently for each group represented by Ar ^{1 to} Ar ^4. Two or less, more preferably one.
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 carbon number thereof is preferably 1-10.

The repeating unit (1) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (1), Ar ¹ is a p-phenylene group (a repeating unit derived from terephthalic acid), Ar ¹ is an m-phenylene group (a repeating unit derived from isophthalic acid), Ar ¹ Is a 2,6-naphthylene group (repeating unit derived from 2,6-naphthalenedicarboxylic acid), and Ar ¹ is a diphenyl ether-4,4′-diyl group (diphenyl ether- 4,4′-dicarboxylic acid-derived repeating units) are preferred.

The repeating unit (2) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine. As the repeating unit (2), Ar ² is a p-phenylene group (a repeating unit derived from hydroquinone, p-aminophenol or p-phenylenediamine), and Ar ² is a 4,4′-biphenylylene group. Those (4,4′-dihydroxybiphenyl, 4-amino-4′-hydroxybiphenyl or repeating units derived from 4,4′-diaminobiphenyl) 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 polymer by the formula amount of each repeating unit). ) And the total value thereof) is preferably 40 mol% or less, more preferably 10 mol% or more and 37.5 mol% or less, and still more preferably 20 mol% or more and 37.5 mol% or less, more More preferably, it is 25 mol% or more and 37.5 mol% or less.

  Similarly, the content of the repeating unit (2) is preferably 40 mol% or less, more preferably 10 mol% or more and 37.5 mol% or less, further preferably 20 mol%, based on the total amount of all repeating units. It is 37.5 mol% or less, more preferably 25 mol% or more and 37.5 mol% or less.

  The content of the mesogenic group derived from hydroxycarboxylic acid is preferably 55 mol% or less, more preferably 20 mol% or more and 50 mol% or less, further preferably 25 mol% or more, based on the total amount of all repeating units. It is 45 mol% or less, More preferably, it is 30 mol% or more and 45 mol% or less. In the liquid crystal polymer, if the content of the mesogenic group derived from the hydroxycarboxylic acid is higher than 55 mol%, the obtained liquid crystal polymer tends to be difficult to dissolve in the solvent described later, so the liquid crystal polymer layer tends to be difficult to obtain. is there.

  The ratio between the content of the repeating unit (1) and the content of the repeating unit (2) is expressed as [content of repeating unit (1)] / [content of repeating unit (2)] (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, a liquid crystal polymer may have 2 or more types of repeating units (1)-(2) each independently. Further, the liquid crystal polymer may have a repeating unit other than the repeating units (1) to (2), but the content thereof is preferably more than 0 mol% to 10% with respect to the total amount of all repeating units. The mol% or less, more preferably more than 0 mol% and 5 mol% or less.

  The liquid crystal polymer has, as the repeating unit (2), one or both of X and Y are imino groups, that is, a repeating unit derived from a predetermined aromatic hydroxylamine, and an aromatic diamine. It is preferable to have either one or both of the repeating unit derived from it because of excellent solubility in a solvent, and as the repeating unit (2), only one of X and Y or both are imino groups More preferably.

  The liquid crystal polymer may be one in which the mesogenic group derived from hydroxycarboxylic acid and the repeating units (1) to (2) are randomly bonded, or may be a block copolymer as long as it exhibits liquid crystallinity.

  The liquid crystal polymer is preferably produced by melt polymerization of raw material monomers corresponding to the repeating units constituting the liquid crystal polymer, and solid-phase polymerization of the obtained polymer (prepolymer). Thereby, a high molecular weight liquid crystal polymer 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 crystal polymer has a flow initiation temperature of preferably 250 ° C. or higher, more preferably 250 ° C. or higher and 350 ° C. or lower, and still more preferably 260 ° C. or higher and 330 ° C. or lower. 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 organic solvents tends to be low, and the viscosity of the solution tends to be high.

The flow start temperature is also called flow temperature or flow temperature, and the liquid crystal polymer is heated at a rate of 4 ° C./min under a load of 9.8 MPa (100 kgf / cm ² ) using a capillary rheometer. 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 crystal polymer (Naoyuki Koide, “ “Liquid Crystal Polymer—Synthesis / Molding / Application—”, CMC Co., Ltd., June 5, 1987, p. 95).

  In the present invention, the liquid crystal polymer layer can be formed of a liquid composition containing the liquid crystal polymer and the solvent as described above. The solvent is preferably an organic solvent, and the organic solvent can dissolve the liquid crystal polymer to be used, specifically at a concentration of 1% by mass or more ([liquid crystal polymer] / [liquid crystal polymer + organic solvent]) at 50 ° C. Those that can be dissolved are appropriately selected and used.

  Examples of organic solvents include halogenated hydrocarbons such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, o-dichlorobenzene; p-chlorophenol, pentachlorophenol, pentafluoro Halogenated phenols such as phenol; 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; Triethylamine and the like Amines; Nitrogen-containing heterocyclic aromatic compounds such as pyridine; Nitriles such as acetonitrile and succinonitrile; Ami such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone System solvents (organic solvents having an amide bond in the molecule); urea compounds such as tetramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethylsulfoxide and sulfolane; and hexamethylphosphoric acid amide and tri-n-butylphosphorus Examples thereof include phosphorus compounds such as acids. Of these organic solvents, two or more organic solvents may be used in combination.

  As the organic solvent, a solvent having an aprotic compound as a main component (aprotic solvent), particularly a solvent having an aprotic compound having no halogen atom as a main component is preferable because it is low in corrosivity and easy to handle. . As this aprotic compound, an amide solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone or the like is preferably used because the liquid crystal polymer is easily dissolved. The proportion of the aprotic compound in the whole organic solvent is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and further preferably 90% by mass to 100% by mass. is there.

The organic solvent is preferably a solvent mainly composed of a compound having a dipole moment of 3 to 5 (unit: Debye) because it easily dissolves the liquid crystal polymer, and is the above-mentioned aprotic compound, It is more preferable to use a compound having a dipole moment of 3 to 5.
The proportion of the compound having a dipole moment of 3 to 5 in the entire organic solvent is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and still more preferably 90% by mass. It is 100 mass% or less.

  Examples of the aprotic compound having a dipole moment of 3 to 5 include dimethyl sulfoxide (dipole moment: 4.1 debye), N, N-dimethylacetamide (3.7 debye), N, N -Dimethylformamide (3.9 debye) and N-methylpyrrolidone (4.1 debye) can be exemplified.

  The organic solvent is preferably a solvent mainly composed of a compound having a boiling point of 220 ° C. or less at 1 atm because it is easy to remove, and is the above-mentioned aprotic compound having a boiling point of 220 at 1 atm. It is more preferable to use a compound having a temperature of 0 ° C. or lower. The proportion of the compound having a boiling point of 220 ° C. or less at 1 atm in the entire organic solvent is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and still more preferably 90% by mass. % Or more and 100% by mass or less.

  Examples of compounds that are aprotic compounds and have a boiling point of 220 ° C. or less at 1 atm include N, N-dimethylacetamide (boiling point: 160 ° C.), N, N-dimethylformamide (boiling point: 153 ° C.), N— An example is methylpyrrolidone (boiling point: 202 ° C.).

(Liquid composition)
The content of the liquid crystal polymer in the liquid composition is preferably 5% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and still more preferably, with respect to the total amount of the liquid crystal polymer and the organic solvent. It is 15 mass% or more and 45 mass% or less, and is adjusted suitably so that the liquid composition of desired viscosity may be obtained.

  In addition, the liquid composition may contain one or more components such as a filler, an additive, and a resin other than the liquid crystal polymer as long as the effects of the three-layer film of the present invention are not impaired.

  Examples of fillers include inorganic fillers such as silica, alumina, titanium oxide, barium titanate, strontium titanate, aluminum hydroxide, calcium carbonate; and leveling agents, cured epoxy resins, crosslinked benzoguanamine resins, crosslinked acrylic resins, etc. The content thereof is preferably 0 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the liquid crystal polymer.

  Examples of the additive include a leveling agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, a flame retardant, and a colorant, and the content thereof is preferably 0 part by mass with respect to 100 parts by mass of the liquid crystal polymer. The amount is 5 parts by mass or less.

  Examples of resins other than liquid crystal polymers include thermoplastic resins other than liquid crystal polymers such as polypropylene, polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether and modified products thereof, and polyether imide; glycidyl Examples include elastomers such as copolymers of methacrylate and polyethylene; and thermosetting resins such as phenol resins, epoxy resins, and cyanate resins, and the content thereof is preferably 0 parts by mass with respect to 100 parts by mass of the liquid crystal polymer. The amount is 20 parts by mass or less.

  The liquid composition can be prepared by mixing the liquid crystal polymer, the organic solvent, and other components used as necessary, all at once or in an appropriate order. When using a filler as another component, it is preferable to prepare by dissolving a liquid crystal polymer in an organic solvent to obtain a liquid composition, and then dispersing the filler in the liquid composition.

In the present invention, the thickness (T2) of the liquid crystal polymer layer satisfies the following formula (b) in relation to the thickness (T1) of the polyimide resin film.
(B) 0.3 ≦ T2 / T1 ≦ 1.5

In the present invention, “the thickness of the liquid crystal polymer layer” means the thickness of each of the liquid crystal polymer layers laminated on both surfaces of the polyimide resin film. Specifically, each of T2a and T2b in FIG. 1 satisfies the above formula (b).
Here, the thickness of the liquid crystal polymer layer is a value represented by an average obtained by measuring the thickness with a contact-type thickness meter at any five locations of the liquid crystal polymer layer. When measuring the thickness of the liquid crystal polymer layer, if it is difficult to directly apply a contact-type thickness gauge, the other layers such as a polyimide resin film are overlapped, You may calculate by measuring thickness and taking the difference with the thickness (what was measured by the method similar to the above) of the other layer overlaid.

  In the present invention, the thickness (T2) of the liquid crystal polymer layer is preferably in the range of 0.35 ≦ T2 / T1 ≦ 1.4 with respect to the thickness (T1) of the polyimide resin film, and 0.4 ≦ A range of T2 / T1 ≦ 1.3 is particularly preferable.

  In the three-layer film of the present invention, for example, when a polyimide resin film having a thickness of 25 μm is adopted, the thickness of the liquid crystal polymer layer is preferably 7.5 μm to 50 μm, more preferably 8 μm to 40 μm, and preferably 9 μm to 35 μm. Particularly preferred.

In the three-layer film of the present invention, the thickness of the liquid crystal polymer layer (T2a and T2b in FIG. 1) is independent from each other and may be the same or different. In the present invention, they are preferably the same, but can be appropriately adjusted and changed as long as the effects of the present invention are achieved and the three-layer film does not warp.
For example, when the polyimide resin film has a hardness that can prevent warping, a difference may be provided in the thickness of the liquid crystal polymer layer (T2a and T2b in FIG. 1).
When the thickness of the liquid crystal polymer layer (T2a and T2b in FIG. 1) is different, for example, the difference between the thickness of T2a and the thickness of T2b is preferably within ± 10%, and within ± 5% Is more preferable, and it is particularly preferably within ± 3%.

  Since the liquid crystal polymer has excellent low hygroscopicity, insulation, mechanical strength, etc., the hygroscopic action of the polyimide resin film having hygroscopicity is highly suppressed by laminating the liquid crystal polymer layer on both sides of the polyimide resin film. be able to. For this reason, even when the printed circuit board or the like in which the metal is laminated on the three-layer film of the present invention is placed in a humid environment or when it is immersed in water, the electrical characteristics due to the hygroscopicity of the polyimide resin film It is possible to suppress deterioration of the material.

In addition, when the thickness (T2) of the liquid crystal polymer layer is equal to or less than the predetermined upper limit value in relation to the thickness (T1) of the polyimide resin film, a metal is laminated on the three-layer film of the present invention. The dimensional stability of the metal laminate can be improved.
Furthermore, when the thickness (T2) of the liquid crystal polymer layer is greater than or equal to the predetermined lower limit in relation to the thickness (T1) of the polyimide resin film, the hygroscopic action of the polyimide resin film can be suppressed to a high level. For this reason, when a metal is laminated on the three-layer film of the present invention, the effect of reducing the transmission loss of the metal laminate can be highly expressed. The three-layer film of the present invention can exhibit a high level of dimensional stability and transmission loss reducing action, particularly when a metal layer is laminated on both sides of the three-layer film. Therefore, the three-layer film of the present invention is preferably used for a laminate obtained by laminating metal layers on both sides of the three-layer film.

As a laminate in which the three-layer film of the present invention can be suitably used, for example, as shown in FIG. 2, a laminate in which metal layers 30a and 30b are laminated on both surfaces of the three-layer film 20 of the present invention can be mentioned. That is, the laminate includes the metal layers 30a and 30b and the three-layer film 20 sandwiched between the metal layers 30a and 30b.
The metal layer is preferably copper, aluminum, silver or an alloy containing one or more metals selected from these. Among these, copper or a copper alloy is preferable because it has more excellent conductivity. The metal layer is preferably made of a metal foil, more preferably a copper foil, because the material is easy to handle, can be easily formed, and is excellent in economy. When providing a metal layer on both surfaces of a three-layer film, the material of these metal layers may be the same and may differ.
The thickness of a metal layer becomes like this. Preferably it is 1-50 micrometers, More preferably, it is 3-35 micrometers, More preferably, it is 5-20 micrometers.
Here, the thickness of a metal layer is the value represented by the average which measured thickness with the contact-type thickness meter in arbitrary five places of a metal layer. When measuring the thickness of the metal layer, if it is difficult to directly apply a contact thickness gauge, the total thickness is the same as described above in a state where other layers such as a liquid crystal polymer layer are overlaid. The thickness may be measured and calculated by taking the difference from the thickness of the other layer that has been superimposed (measured by the same method as described above).

≪Three-layer film production method 1≫
In a second aspect of the present invention, a liquid composition containing a solvent and a liquid crystal polymer is applied onto a polyimide resin film, and the liquid composition coating step of covering the polyimide resin film with the liquid composition; and the liquid composition It is a manufacturing method of the three-layer film of the 1st aspect of this invention including the solvent removal process which removes the solvent in, and a heat processing process, Comprising: As said liquid crystal polymer, 2-hydroxybenzoic acid or 2- It is the manufacturing method of the three-layer film of the 1st aspect of this invention characterized by including the structural unit derived from hydroxy-6-naphthoic acid and the following structural units (1)-(2).
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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.)

[Liquid composition coating process]
The manufacturing method of the three-layer film of this invention has the liquid composition application | coating process which apply | coats the liquid composition containing a solvent and a liquid crystal polymer on a polyimide resin film, and covers the said polyimide resin film with the said liquid composition.
The explanation regarding the liquid composition containing the solvent and the liquid crystal polymer and the polyimide resin film is the same as the explanation in the three-layer film of the present invention.
Examples of the method for applying the liquid composition onto the polyimide resin film include various means such as a roller coating method, a dip coater method, a spray coater method, a curtain coating method, a slot coating method, and a screen printing method. The temperature during application is preferably 10 to 40 ° C.

  In this invention, a liquid composition is apply | coated to both surfaces of a polyimide resin film with said application | coating method. At this time, the coating amount of the liquid composition is adjusted so that the liquid crystal polymer layer has the predetermined thickness.

[Solvent removal step]
After the [liquid composition coating step], the solvent in the liquid composition is removed.
Here, the method for removing the solvent is not particularly limited, but it is preferably performed by evaporation of the solvent. Examples of the method for evaporating the solvent include methods such as heating, reduced pressure, and ventilation. Among them, heating and evaporation are preferable from the viewpoints of production efficiency and handleability, and heating and evaporation can be performed while ventilating. More preferred.
The heat treatment in the solvent removal step may be appropriately selected depending on the solvent applied to the solution composition, may be heat-treated at 60 to 200 ° C. for 60 to 600 seconds, and preferably 120 to 600 seconds. By setting it as more than a lower limit, a solvent is fully removed and blocking is suppressed in the obtained three-layer film.
Further, the removal of the solvent in the [solvent removal step] is not necessarily complete, and the remaining solvent may be removed in the next [heat treatment step]. From the viewpoint of preventing surface roughness of the liquid crystal polymer layer, it is preferable to remove the solvent by this [solvent removing step].

[Heat treatment process]
After the [solvent removing step], heat treatment is performed. As the heat treatment, for example, a method of heating by heating the three-layer film under an inert gas atmosphere can be employed. What is necessary is just to adjust heat processing conditions suitably with the employ | adopted liquid composition, for example, what is necessary is just to carry out for 1 minute to 4 hours in the range of 250 to 400 degreeC.

  In the method for producing a three-layer film of the second aspect of the present invention, first, a liquid composition is applied to one side of a polyimide resin film, and the solvent in the liquid composition is removed. Next, this operation is repeated on the other surface, and finally the heat treatment is performed, whereby the three-layer film of the first aspect of the present invention can be obtained.

≪Three-layer film production method 2≫
In a third aspect of the present invention, a liquid composition containing a solvent and a liquid crystal polymer is impregnated with a polyimide resin film, the impregnation step of covering the polyimide resin film with the liquid composition, and the solvent in the liquid composition And a heat treatment step, wherein the liquid crystal polymer is a structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid, and It is a manufacturing method of the 3 layer film of the 1st aspect of this invention characterized by containing a structural unit.
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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.)

[Impregnation process]
In the impregnation step, a polyimide resin film is impregnated in a liquid composition containing a solvent and a liquid crystal polymer. The impregnation time is preferably 30 seconds to 5 minutes. The temperature during impregnation is preferably 10 to 40 ° C.
The explanation regarding the liquid composition containing the solvent and the liquid crystal polymer and the polyimide resin film is the same as the explanation in the three-layer film of the present invention.
After the impregnation step, the polyimide resin film impregnated with the liquid composition is passed between a pair of rolls whose interval is narrower than its thickness. By this step, the liquid composition excessively attached to the surface of the polyimide resin film can be removed.

FIG. 3 is a schematic view for explaining a method of continuously performing an impregnation step and a roll passage step using a long polyimide resin film. However, what is shown here is an example, and the impregnation step in the present invention is not limited to the one shown here.
Polyimide resin film 10 is induced by the guide roller 4 and the guide rollers G ₁ moves in the arrow direction, is dipped in the liquid composition W immersion tank 3, then a polyimide resin film 11 immediately after the liquid composition impregnated, It is pulled up from the immersion tank 3 and sent to a squeeze roll 5 having a pair of rolls 5A and 5B. The pair of rolls 5A and 5B are arranged so as to sandwich the polyimide resin film 11, and the distance between them is at least the thickness of the polyimide resin film 11 (the polyimide resin film 10 and the liquid composition W impregnated therein). Is adjusted to be narrower than the total thickness including). The polyimide resin film 11 is squeezed by passing between such a pair of rolls 5A and 5B, and an excess liquid composition is removed and the liquid composition is sufficiently impregnated inside. The impregnated polyimide resin film 12 is obtained.

  The pair of rolls 5 </ b> A and 5 </ b> B may rotate by itself (self-rotating), or may rotate with the travel of the polyimide resin film 11 immediately after impregnation with the liquid composition. When the pair of rolls 5A and 5B are self-rotating, the amount of the liquid composition adhered to the liquid composition-impregnated polyimide resin film 12 can be easily adjusted. The surface is also sufficiently smoothed and the smoothness of the surface is improved.

  The film thickness of the liquid crystal polymer layer is obtained by adjusting the pulling rate from the dipping tank 3 and the distance between the pair of rolls 5A and 5B in the squeeze roll 5 to obtain a three-layer film adjusted to a predetermined film thickness. Can do.

The description regarding the [solvent removing step] and the [heating step] in the third aspect of the present invention is the same as the description in the second aspect of the present invention.
Specifically, as the [solvent removing step], the liquid composition-impregnated polyimide resin film that has passed between the rolls 5A and 5B may be heat-treated at 60 to 200 ° C. for 60 to 600 seconds, and for 120 to 600 seconds. Preferably there is.
By this heat treatment, the solvent of the liquid composition impregnated in the liquid composition-impregnated polyimide resin film is removed by evaporation, and the intended three-layer film is obtained.
And as a [heating process], what is necessary is just to heat-process in the range of 250 to 400 degreeC for 1 minute to 4 hours, for example. By setting the temperature and time of the heat treatment in this way, a three-layer film with reduced voids can be stably obtained.

≪Three-layer film manufacturing method 3≫
The fourth aspect of the present invention includes a step of preparing a liquid composition containing a solvent and a liquid crystal polymer, and a polyamic acid resin liquid composition that is a precursor of a polyimide resin, the liquid composition on a support, The step of applying the polyamic acid resin liquid composition and the liquid composition in this order to three layers, the solvent removing step of removing the solvent in the liquid composition of the three layers, and the heat treatment step are included. A production method, wherein the liquid crystal polymer contains a structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid and the following structural unit: It is a manufacturing method of the three-layer film of an aspect.
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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.)

[Polyamic acid resin liquid composition]
The polyimide resin is obtained by a dehydration conversion reaction from a polyimide precursor, that is, a polyamic acid. As a method for performing the conversion reaction, two methods are known: a thermal curing method that uses only heat and a chemical curing method that uses a chemical dehydrating agent.
A polyamic acid can be obtained by polymerizing tetracarboxylic dianhydride and diamine as raw materials, as described in Patent Document 1, for example. By treating the polyamic acid with heating at 200 ° C. or higher (thermal cure method) or a chemical ring-closing agent (chemical cure method), a dehydration / cyclization reaction can proceed to obtain a polyimide resin.

[A step of applying a liquid composition containing a solvent and a liquid crystal polymer on a support, a polyamic acid resin liquid composition, and a liquid composition containing a solvent and a liquid crystal polymer in this order in three layers]
In this step, glass or the like is usually used as the support, but a conductor can also be used. Examples of such conductors include metal plates or metal foils such as gold, silver, copper, aluminum, nickel, and stainless steel.
As a method of casting a liquid composition containing a solvent and a liquid crystal polymer and a polyamic acid resin liquid composition on a support, the liquid composition containing the solvent and the liquid crystal polymer or a polyamic acid resin liquid composition is required. The liquid composition containing the solvent and the liquid crystal polymer and the foreign material contained in the polyamic acid resin liquid composition are removed by filtration using a filter or the like, and then the roller coating method, dip coating method, spraying is performed on the support. The film can be obtained by smooth and uniform casting by various means such as a coating method, a spinner coating method, a curtain coating method, a slot coating method, and a screen printing method, and then removing the solvent.
On the support, a liquid composition containing a solvent and a liquid crystal polymer, a polyamic acid resin liquid composition, and a liquid composition containing a solvent and a liquid crystal polymer are applied in this order in three layers. At this time, the coating amount of the liquid composition containing the solvent and the liquid crystal polymer is adjusted so that the liquid crystal polymer layer has the predetermined thickness.

  The description regarding the [solvent removing step] in the fourth aspect of the present invention is the same as the description in the second aspect of the present invention.

[Three-layer film formation process]
Subsequently, it heat-processes and a support body is peeled and a three-layer film can be obtained. Here, instead of heat treatment, treatment with a chemical ring-closing agent may be performed. As the chemical ring-closing agent in this case, those used for obtaining polyimide from polyamic acid can be used, and for example, pyridine, acetic anhydride, benzoic acid and the like are used. In the case of heat treatment, the temperature is preferably set to 250 to 400 ° C. in a nitrogen atmosphere.

In the method for producing a three-layer film according to the fourth aspect of the present invention, first, a liquid composition containing a solvent and a liquid crystal polymer is applied on a support, and the solvent in the liquid composition is removed. Next, a polyamic acid resin liquid composition is applied, and the solvent of the polyamic acid resin liquid composition is removed. Further, a liquid composition containing a solvent and a liquid crystal polymer is applied, and the solvent in the liquid composition is removed. Finally, a three-layer film can be obtained by performing treatment with a heat treatment or a chemical ring-closing agent and peeling from the support.
In the method for producing a three-layer film of the fourth aspect of the present invention, a liquid composition containing a solvent and a liquid crystal polymer, a polyamic acid resin liquid composition, and a liquid containing a solvent and a liquid crystal polymer on a support. The composition is applied in this order, and the solvent in the liquid composition is removed. Finally, a three-layer film may be obtained by performing treatment with a heat treatment or a chemical ring-closing agent and peeling from the support.

≪Laminated board≫
A fifth aspect of the present invention is a laminated board in which the three-layer film obtained by the second to fourth aspects is used as an insulating layer, and a metal layer is formed on at least one surface of the insulating layer.
In the laminate of the present invention, it is sufficient that a metal layer is formed on at least one side of the three-layer film, but it is preferable that metal layers are laminated on both sides. That is, it is preferable that the laminated board contains the 1st and 2nd metal layer and the three-layer film pinched | interposed into the 1st and 2nd metal layer. More specifically, the laminate shown in FIG. 2 is a laminate in which metal layers are laminated on both surfaces of the three-layer film, and 30a and 30b in FIG. 2 are laminates.

The metal layer laminated | stacked on the said three-layer film is demonstrated.
The metal layer in the laminated board of the present invention is a copper foil having a tensile modulus after heat treatment at 300 ° C. of 60 GPa or less and a stress at break of 150 MPa or less. The lower limit related to the tensile modulus is 10 GPa or more in a practical range, and preferably 20 GPa or more. The lower limit related to the stress at break is preferably 20 MPa or more and particularly preferably 30 MPa or more in a practical range. The type of metal layer used in the present invention may be either a layer formed by electrolysis or a layer formed by rolling. In order to obtain a copper foil as an example of a metal layer having the above characteristics, Is a technique defined by JIS C2151 from high temperature elongation (high temperature high elongation copper foil, hereinafter referred to as “HTE copper foil”) and a rolled copper foil, which are well known in the art. The tensile modulus and stress at break can be determined and selected.

The thickness of the metal layer used in the laminate of the present invention is preferably in the range of more than 5 μm and not more than 35 μm. In particular, it is preferably in the range of 9 to 28 μm. It is preferable for the thickness of the metal layer to be in the above range because the tension of the metal layer can be easily adjusted during the production of the laminate, and the flexibility of the resulting laminate is further improved.
Here, the thickness of a metal layer is the value represented by the average which measured thickness with the contact-type thickness meter in arbitrary five places of a metal layer. When measuring the thickness of the metal layer, if it is difficult to directly apply the contact thickness gauge, the total thickness is the same as above with other layers such as a three-layer film overlapped. The thickness may be measured and calculated by taking the difference from the thickness of the other layer that has been superimposed (measured by the same method as described above).
Further, the maximum height (Rz) of the metal layer in the laminate is preferably in the range of 0.5 to 2.5 μm, more preferably in the range of 0.6 to 2.4 μm. A range of 6 to 2.2 μm is particularly preferable.
Specific examples of preferable metal layers to be applied to the present invention include copper foils. Among them, HTE copper foils include, for example, SQ-HTE copper foil (manufactured by Mitsui Metal Mining Co., Ltd.), 3EC-M3S-HTE copper. Foil (made by Mitsui Kinzoku Mining Co., Ltd.), NS-HTE copper foil (made by Mitsui Kinzoku Mining Co., Ltd.), 3EC-HTE copper foil (made by Mitsui Kinzoku Mining Co., Ltd.), F2-WS copper foil (made by Furukawa Electric Co., Ltd.), HLB (Japan) Electrolytic Co., Ltd.), CF-T4X-DS-SVR (Fukuda Metal Foil Powder Co., Ltd.), etc., and examples of rolled copper foil include RCF-T5B-HPC (Fukuda Metal Foil Powder Co., Ltd.), BHY-22B- T (manufactured by JX Nippon Mining & Metals), BHY-22B-HA (manufactured by JX Nippon Mining & Metals), BHYA-T (manufactured by JX Nippon Mining & Metals), BHYA-HA (manufactured by JX Nippon Mining & Metals) ) And the like. These copper foils are readily available from the market.

  By using the copper foil having the above characteristics for the laminate of the present invention, a laminate having excellent adhesion between the metal layer and the resin layer and excellent flexibility and folding resistance can be realized.

As a method for integrating the three-layer film and the metal layer, a method of hot pressing the metal layer and the three-layer film is preferably used. For example, a method of performing hot pressing by holding at a pressure of 200 to 350 ° C. and a pressure of 3 to 10 MPa for 10 to 60 minutes using a conventional press machine can be mentioned.
The liquid crystal polymer laminate of the present invention thus obtained is a multilayer printed circuit board for a semiconductor package or a mother board obtained by a build-up method or the like that has been attracting attention in recent years due to excellent characteristics such as dimensional stability and low hygroscopicity. It is suitably used for flexible printed wiring boards, tape automated bonding films, and the like.

<Printed circuit board>
A sixth aspect of the present invention is a printed circuit board using the three-layer film as an insulating layer. The printed circuit board of the present invention can have the same configuration as a known printed circuit board except that the three-layer film is used as an insulating layer, and can be manufactured by the same method. That is, the printed circuit board includes an insulating layer including a three-layer film and a circuit pattern located on the three-layer film. In other words, the printed circuit board includes an insulating layer including at least one three-layer film and a circuit pattern formed on at least one of the first surface and the second surface of the insulating layer. The insulating layer may consist of one three-layer film, or a plurality of three-layer films may be laminated. The circuit pattern may be located only on the first surface, the first circuit pattern may be located on the first surface, and the second circuit pattern may be located on the second surface.

  In the printed circuit board of the present invention, for example, a metal layer is provided on one side or both sides of an insulating layer made of a single three-layer film or an insulating layer formed by laminating a plurality of the three-layer films. A laminated body is produced, a predetermined circuit pattern is formed on the metal layer of the laminated body by etching or the like, and the laminated body on which this circuit pattern is formed is laminated as it is or as needed, Can be manufactured. The printed circuit board of the present invention is preferably one in which metal layers are laminated on both sides of a three-layer film. That is, the printed circuit board includes a three-layer film, a first circuit pattern located on the first surface of the three-layer film, and a second circuit pattern located on the second surface of the three-layer film. Is preferred.

  In the case of an insulating layer in which a plurality of the three-layer films are laminated, the plurality of three-layer films may all be the same, only a part may be the same, or all may be different. The number of sheets is not particularly limited as long as it is two or more. Such an insulating layer can be produced, for example, by laminating a plurality of three-layer films in the thickness direction, heat-pressing and fusing them together.

The material of the metal layer is preferably copper, aluminum, silver or an alloy containing one or more metals selected from these. Of these, copper or a copper alloy is preferable from the viewpoint of having superior conductivity. The metal layer is preferably made of a metal foil, more preferably a copper foil, because the material is easy to handle, can be easily formed, and is excellent in economy. When providing a metal layer on both surfaces of an insulating layer, the material of these metal layers may be the same and may differ.
The thickness of a metal layer becomes like this. Preferably it is 1-50 micrometers, More preferably, it is 3-35 micrometers, More preferably, it is 5-20 micrometers.
Here, the thickness of a metal layer is the value represented by the average which measured thickness with the contact-type thickness meter in arbitrary five places of a metal layer. When measuring the thickness of the metal layer, if it is difficult to directly apply the contact thickness gauge, the total thickness is the same as above with other layers such as a three-layer film overlapped. The thickness may be measured and calculated by taking the difference from the thickness of the other layer that has been superimposed (measured by the same method as described above).

  As a method of providing a metal layer, a method of fusing a metal foil to the surface of the insulating layer, a method of adhering the metal foil to the surface of the insulating layer with an adhesive, a plating method, a screen printing method or a sputtering method on the surface of the insulating layer Can be exemplified by a method of coating with metal powder or metal particles.

  When the insulating layer is formed by laminating a plurality of the three-layer films, the three-layer films are arranged in the thickness direction, and the surface of one or both of the three-layer films located on the outermost side is arranged. In addition, when the insulating layer is formed by further pressing the metal foil and pressing the metal foil and the plurality of three-layer films, the metal layer can be simultaneously provided on one side or both sides of the insulating layer.

A circuit pattern is formed by patterning the metal layer. Examples of the method for forming the circuit pattern include etching. Etching (processing) will be briefly described. First, the metal layer is masked so that the metal layer has a predetermined circuit pattern. Next, in the masked metal layer portion and the unmasked metal layer portion, the latter metal layer portion is removed by an etching process called a wet method (chemical treatment). As a chemical | medical agent used for this etching process, ferric chloride aqueous solution is mentioned, for example. As the masking, a commercially available etching resist or dry film may be used.
Next, the etching resist and the dry film are removed from the masked metal layer portion with acetone or a sodium hydroxide aqueous solution. By patterning the metal layer in this way, a predetermined circuit pattern (wiring) can be formed.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely using an Example, this invention is not limited by an Example.

<Production Example 1>
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas introduction pipe, a thermometer, and a reflux condenser, 2-hydroxy-6-naphthoic acid (hereinafter referred to as “HNA”) 677.4 g (3.6) Mol), 4-hydroxyacetonilide (hereinafter referred to as “APAP”) 332.6 g (2.2 mol), isophthalic acid (hereinafter referred to as “IPA”) 99.7 g (0.6) Mol), 413.2 g (1.6 mol) of diphenyl ether-4,4′-dicarboxylic acid (hereinafter referred to as “DEDA”), and 673.8 g (6.6 mol) of acetic anhydride.
After sufficiently replacing the inside of the reactor with nitrogen gas, the temperature was raised to 150 ° C. over 15 minutes under a nitrogen gas stream, and the temperature was maintained and refluxed for 3 hours.
Thereafter, the temperature was raised to 320 ° C. over 170 minutes while distilling off the by-product acetic acid and unreacted acetic anhydride, and the time when an increase in torque was observed was regarded as the completion of the reaction, and the contents were taken out. The obtained solid content was cooled to room temperature, pulverized with a coarse pulverizer, and confirmed to show a schlieren pattern peculiar to a liquid crystal phase at 230 ° C. by observation with a polarizing microscope (ECLIPSE LV100POV manufactured by NIKON). Further, the powdery liquid crystal polymer was held at 250 ° C. for 3 hours under a nitrogen atmosphere to proceed the polymerization reaction in a solid phase. 100 g of the obtained liquid crystal polymer powder was added to 900 g of N-methyl-2-pyrrolidone, heated to 120 ° C. and completely dissolved to obtain a brown transparent liquid crystal polymer solution composition (1).

<Production Example 2>
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser, 4-hydroxyacetanilide (hereinafter referred to as “APAP”) 332.6 g (2.2 mol), isophthalate Acid (hereinafter referred to as “IPA”) 99.7 g (0.6 mol), diphenyl ether-4,4′-dicarboxylic acid (hereinafter referred to as “DEDA”) 413.2 g (1.6 mol) ) And acetic anhydride 269.5 (2.6 mol). After sufficiently replacing the inside of the reactor with nitrogen gas, the temperature was raised to 150 ° C. over 15 minutes under a nitrogen gas stream, and the temperature was maintained and refluxed for 3 hours.
Thereafter, the temperature was raised to 320 ° C. over 170 minutes while distilling off the by-product acetic acid and unreacted acetic anhydride, and the time when an increase in torque was observed was regarded as the completion of the reaction, and the contents were taken out. The obtained solid was cooled to room temperature, pulverized with a coarse pulverizer, and then observed with a polarizing microscope while raising the temperature from room temperature to 400 ° C., but no schlieren pattern peculiar to the liquid crystal phase could be observed.

[Example 1]
The liquid crystal polymer solution composition (1) was applied on one side using a film applicator (applied thickness: 100 μm) on a 25 μm thick Kapton H (made by Toray DuPont), which is a commercially available polyimide resin film, and heated with a hot air dryer. The solvent is removed by heating at 100 ° C., and this operation is repeated on the other side, and heat treatment is performed at 300 ° C. with a high-temperature hot air dryer to form a three-layer film (liquid crystal polymer / polyimide / liquid crystal polymer = 10 μm / 25 μm / 10 μm) was obtained.

  The three-layer film obtained above was used as an insulating layer, and copper foil (“BHY-22B-T” (thickness 18 μm, Rz = 0.7 μm) manufactured by JX Nippon Mining & Metals) was laminated on both sides thereof. . This is hot-pressed and integrated for 20 minutes at a temperature of 340 ° C. and a pressure of 5 MPa with a high-temperature vacuum press (“KVHC-PRESS” manufactured by Kitagawa Seiki Co., Ltd., length 300 mm, width 300 mm). A double-sided copper-clad laminate was obtained.

  About the double-sided copper clad laminated board obtained above, TDR measurement was performed and a printed circuit board was produced so as to be 50Ω. As a result, a circuit pattern having a ground width of 110 μm and a length of 100 mm was formed.

<Transmission loss measurement>
The transmission loss (S21 parameter) of the printed circuit pattern on which the circuit pattern was formed was measured using a measurement probe “E8363B” manufactured by Agilent Technologies. Transmission loss at frequencies of 5 GHz, 10 GHz, 20 GHz, and 40 GHz was measured before and after immersion in water at 23 ° C. for 48 hours.
Tables 3 and 4 show the transmission loss at 5 GHz, 10 GHz, 20 GHz, and 40 GHz before immersion in water. Tables 3 and 4 show the rate of change in transmission loss (frequency 5 GHz) before and after immersion at 23 ° C. for 48 hours.

<Dimensional stability evaluation>
Using a ferric chloride solution (Kida Co., Ltd., 40 ° Baume), all the copper foil was removed from the double-sided copper-clad laminate, and in accordance with JIS C6481, “Copper-clad laminate test method for printed wiring boards” Using a thermomechanical analyzer ("Thermo plus TMA8310" manufactured by Rigaku Corporation), applying a load of 2.5 g to a 20 mm x 50 mm test piece (insulating layer), up to 250 ° C under a nitrogen stream at 5 ° C / min. The in-plane thermal expansion coefficient at the time of temperature increase was measured (temperature range: 50 to 250 ° C .: 1 St scan). The results are shown in Tables 1 and 2.

[Example 2]
A copper clad laminate was prepared in the same manner as in Example 1 except that the film applicator coating thickness was changed to 200 μm to obtain a three-layer film (liquid crystal polymer / polyimide / liquid crystal polymer = 20 μm / 25 μm / 20 μm). did. The obtained copper-clad laminate was subjected to TDR measurement to produce a printed circuit board so as to have a resistance of 50Ω. As a result, the wiring width was 142 μm and the length was 100 mm.

[Example 3]
A copper clad laminate was produced in the same manner as in Example 1 except that a commercially available polyimide resin film having a film thickness of 25 μm, Upilex S (manufactured by Ube Industries) was used. The obtained copper-clad laminate was subjected to TDR measurement and a printed circuit board was produced so as to have a resistance of 50Ω. As a result, the wiring width was 110 μm and the length was 100 mm.

[Example 4]
In Example 1, the same operation was performed except that a copper foil (F2-WS manufactured by Furukawa Electric Co., Ltd. (thickness: 18 μm, Rz = 2.1 μm)) was laminated to produce a copper-clad laminate. . The obtained copper-clad laminate was subjected to TDR measurement and a printed circuit board was prepared to have a resistance of 50Ω. As a result, the wiring width was 110 μm and the length was 100 mm.

[Example 5]
A copper clad laminate was prepared in the same manner as in Example 1 except that the film applicator coating thickness was changed to 250 μm to obtain a three-layer film (liquid crystal polymer / polyimide / liquid crystal polymer = 25 μm / 25 μm / 25 μm). did.

[Example 6]
In Example 1, the same operation was performed except that the coating thickness of the film applicator was changed to 335 μm to obtain a three-layer film (liquid crystal polymer / polyimide / liquid crystal polymer = 33.5 μm / 25 μm / 33.5 μm). A laminate was prepared.

[Comparative Example 1]
A copper clad laminate was prepared in the same manner as in Example 1 except that the coating thickness of the film applicator was changed to 50 μm to obtain a three-layer film (liquid crystal polymer / polyimide / liquid crystal polymer = 5 μm / 25 μm / 5 μm). did. The obtained copper-clad laminate was subjected to TDR measurement to produce a printed circuit board so as to have a resistance of 50Ω. As a result, the wiring width was 95 μm and the length was 100 mm. It was found that the change in transmission loss before and after immersion in water was as large as 23%.

[Comparative Example 2]
TDR measurement was performed using Espanex-MB (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., polyimide film thickness 50 μm) which is a copper-clad laminate using a commercially available polyimide resin film, and a printed circuit board was prepared so as to be 50Ω. As a result, the wiring width was 110 μm and the length was 100 mm.
Next, the transmission loss (S21 parameter) of the printed circuit board was measured for the model sample using a measurement probe “E8363B” manufactured by Arranged Technology Co., Ltd.
It was found that the change in transmission loss before and after immersion in water was as large as 35%.

[Comparative Example 3]
The liquid crystal polymer solution composition (1) is applied to a film applicator (coating thickness 500 μm) on a copper foil (“BHY-22B-T” (thickness 18 μm, Rz = 0.7 μm) manufactured by JX Nippon Mining & Metals) ) Was applied at 100 ° C. using a hot air dryer to remove the solvent, and heat treated at 300 ° C. using a high temperature hot air dryer to obtain a single-sided copper-clad laminate (50 μm).

  A copper foil (“BHY-22B-T” (thickness 18 μm, Rz = 0.7 μm) manufactured by JX Nippon Mining & Metals) was further laminated on the liquid crystal polymer of the single-sided copper-clad laminate obtained above. By hot pressing for 20 minutes at a temperature of 340 ° C. and a pressure of 5 MPa with a high-temperature vacuum press (“KVHC-PRESS” manufactured by Kitagawa Seiki Co., Ltd., 300 mm long and 300 mm wide), and integrated. A double-sided copper-clad laminate was obtained.

  Using a ferric chloride solution (Kida Co., Ltd., 40 ° Baume), all copper foil is removed from the double-sided copper-clad laminate, and in accordance with JIS C6481, “Test method for copper-clad laminate for printed wiring” Using a mechanical analyzer ("Thermo plus TMA8310" manufactured by Rigaku Corporation), while applying a load of 2.5 g to a 20 mm x 50 mm test piece (insulating layer), the temperature was increased to 250 ° C at 5 ° C / min. The in-plane thermal expansion coefficient at the time of temperature was measured (temperature range: 50 to 250 ° C., 1 St scan). Compared to the three-layer film, it was found that the film expanded greatly and the dimensional change was large.

[Comparative Example 4]
A commercially available liquid crystal polymer film (Kuraray Bexter 50 μm) was used as an insulating layer and copper foil on both sides thereof (“BHY-22B-T” (thickness 18 μm, Rz = 0.7 μm) manufactured by JX Nippon Mining & Metals) ). This is hot-pressed and integrated for 20 minutes at a temperature of 340 ° C. and a pressure of 5 MPa with a high-temperature vacuum press (“KVHC-PRESS” manufactured by Kitagawa Seiki Co., Ltd., length 300 mm, width 300 mm). A double-sided copper-clad laminate was obtained.

  Using a ferric chloride solution (Kida Co., Ltd., 40 ° Baume), all copper foil is removed from the double-sided copper-clad laminate, and in accordance with JIS C6481, “Test method for copper-clad laminate for printed wiring” Using a mechanical analyzer ("Thermo plus TMA8310" manufactured by Rigaku Corporation), while applying a load of 2.5 g to a 20 mm x 50 mm test piece (insulating layer), the temperature was increased to 250 ° C at 5 ° C / min. The in-plane thermal expansion coefficient at the time of temperature was measured (temperature range: 50 to 250 ° C., 1 St scan). Compared with the three-layer film, it was found that the shrinkage was large and the dimensional change was large.

As shown in the above results, the double-sided copper-clad laminates of Examples 1 to 4 using the three-layer film of the present invention were compared with the double-sided copper-clad laminate of Comparative Example 1 and the rate of change in transmission loss before and after water immersion. The dimensional stability was also good.
Moreover, even when the liquid crystal polymer layer was made thick as in Examples 5 to 6, the dimensional stability was good. Since the three-layer film of Examples 5 to 6 has a thick liquid crystal polymer layer, when the printed circuit board was produced using the three-layer film of Examples 5 to 6, the rate of change in transmission loss of the printed circuit board was The effect that it becomes equivalent to Example 1-4 or lower than it can fully be show | played.
In addition, since Comparative Example 3-4 had a large dimensional change compared with the three-layer film of this invention, the transmission loss was not measured.

  As mentioned above, in the Example of this specification, the three-layer film was manufactured by apply | coating the liquid composition containing a solvent and a liquid crystal polymer on a polyimide resin film. In addition to this method, the three-layer film can also be produced in the following <Method for producing a three-layer film by impregnation> or <Method for producing a three-layer film by sequential application>, and a three-layer film produced by the method, The three-layer film produced in the above example has the same effect.

<Method for producing three-layer film by impregnation>
A commercially available polyimide resin film Kapton 200H (manufactured by Toray DuPont Co., Ltd .; 50 μm) was dipped in the liquid crystal polymer solution composition (1) for 1 minute at room temperature and then pulled up to remove the liquid crystal polymer excessively attached to the surface. After passing between these rolls, the solvent is evaporated with a hot air dryer, and further, a heat treatment is performed using a high-temperature hot air dryer to produce a three-layer film.
At this time, the film thickness of the liquid crystal polymer can also be adjusted by adjusting the pulling rate.

<Three-layer film manufacturing method by sequential application>
As a support, a liquid crystal polymer solution composition (1), a polyamic acid resin liquid composition, and a liquid crystal polymer solution composition (1) were applied in this order on a SUS foil, and the solvent was heated at 100 ° C. using a hot air dryer. Then, a heat treatment is performed at 330 ° C., and a three-layer film can be produced by peeling from the support.

DESCRIPTION OF SYMBOLS 20 ... Three-layer film, 21 ... Polyimide resin film, 22a, 22b ... Liquid crystal polymer layer, 30a, 30b ... Metal layer, 3 ... Dipping tank, 4 ... Guide roller, 5 ... squeeze roll, 5A, 5B ... roll, 10 ... polyimide resin film, 11 ... polyimide resin film immediately after impregnation with liquid composition, 12 ... liquid composition impregnation polyimide resin film, W ..Liquid composition, G ₁ ... guide roller

Claims (10)

A liquid crystal polymer layer having a hydroxycarboxylic acid as a mesogen group is laminated on both surfaces of the polyimide resin film, and the thickness (T1) of the polyimide resin film and the thickness of a liquid crystal polymer layer having the hydroxycarboxylic acid as a mesogen group (T2). Is a three-layer film satisfying the following relational expressions (a) and (b) (however, two T2s are independent of each other and may be the same or different).
(A) 20 μm ≦ T1 ≦ 50 μm
(B) 0.3 ≦ T2 / T1 ≦ 1.5   The three-layer film according to claim 1, wherein the liquid crystal polymer layer having a hydroxycarboxylic acid as a mesogen group contains a structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid. Furthermore, the three-layer film of Claim 1 or 2 in which the liquid crystal polymer layer which uses the said hydroxycarboxylic acid as a mesogen group contains the following structural units (1) and (2).
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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 laminated board by which the three-layer film as described in any one of Claims 1 thru | or 3 is used as an insulating layer, and the metal layer is formed in the at least single side | surface of this insulating layer.   The laminated plate according to claim 4, wherein the maximum height (Rz) of the metal layer is 0.5 to 2.5 μm.   The laminate according to claim 4 or 5, wherein the metal layer contains copper.   The printed circuit board using the laminated board as described in any one of Claims 4 thru | or 6. Applying a liquid composition containing a solvent and a liquid crystal polymer on the polyimide resin film, and covering the polyimide resin film with the liquid composition; and
A solvent removal step of removing the solvent in the liquid composition;
A heat treatment step;
A method for producing a three-layer film comprising:
The manufacturing method of the three-layer film containing the structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid as the said liquid crystal polymer, and the following structural units.
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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.) Impregnating a polyimide resin film in a liquid composition containing a solvent and a liquid crystal polymer, and covering the polyimide resin film with the liquid composition;
A solvent removal step of removing the solvent in the liquid composition;
A heat treatment step;
A method for producing a three-layer film comprising:
A method for producing a three-layer film comprising a structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid and the following structural units (1) and (2) as the liquid crystal polymer.
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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.) Preparing a liquid composition containing a solvent and a liquid crystal polymer, and a polyamic acid resin liquid composition that is a precursor of a polyimide resin;
Applying the liquid composition, the polyamic acid resin liquid composition, and the liquid composition on a support in this order in three layers;
A solvent removal step of removing the solvent in the three-layer liquid composition;
A three-layer film forming process;
A method for producing a three-layer film comprising:
A method for producing a three-layer film comprising a structural unit derived from 2-hydroxybenzoic acid or 2-hydroxy-6-naphthoic acid and the following structural units (1) and (2) as the liquid crystal polymer.
(1) —CO—Ar ¹ —CO—
(2) ^-X-Ar 2 -Y-
(In the formula, Ar ¹ and Ar ² each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (3). X and Y each independently represents an oxygen atom or an imino group. (The hydrogen atom in the group represented by Ar ¹ or Ar ² may be independently substituted with a halogen atom, an alkyl group or an aryl group.)
^{(3) -Ar 3 -Z-Ar} 4 -
(Ar ³ and Ar ⁴ 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.)

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