JP6403503B2 - Copper-clad laminate, printed wiring board and method of using the same - Google Patents

Description

  The present invention relates to a copper clad laminate having a polyimide insulating layer and a copper foil layer, a printed wiring board obtained by processing a copper foil layer of the copper clad laminate, and a method of using the same.

  In recent years, with the progress of downsizing, weight reduction, and space saving of electronic devices, flexible printed wiring boards (FPCs) that are thin, light, flexible, and have excellent durability even after repeated bending are used. The demand for Circuits) is increasing. FPC can be mounted three-dimensionally and densely in a limited space. For example, it can be used for wiring of movable parts of electronic devices such as HDDs, DVDs, mobile phones, and parts such as cables and connectors. It is expanding.

  In addition to the above-described higher density, higher performance of equipment has been advanced, so that it is necessary to cope with higher frequency transmission signals. In information processing and information communication, efforts are being made to increase the transmission frequency in order to transmit and process large amounts of information, and printed circuit board materials are subject to transmission loss due to thinning of the insulating layer and low dielectric constant of the insulating layer. Decrease is required. Conventional FPC using polyimide has a high dielectric constant and dielectric loss tangent of polyimide, and has a high transmission loss in a high frequency region, so that it is difficult to adapt to high frequency. Therefore, so far, in order to cope with higher frequencies, FPCs using a liquid crystal polymer characterized by a low dielectric constant and a low dielectric loss tangent as a dielectric layer have been mainly used. However, although the liquid crystal polymer is excellent in dielectric properties, there is room for improvement in heat resistance and adhesion to metal foil.

  In order to improve heat resistance and adhesiveness, a metal-clad laminate using polyimide as an insulating layer has been proposed (Patent Document 1). According to Patent Document 1, it is known that the dielectric constant is generally lowered by using an aliphatic monomer as a polymer material. However, an aliphatic (chain) tetracarboxylic dianhydride is used. The heat resistance of the polyimide obtained by use is remarkably low, so that it cannot be used for processing such as soldering, and has a practical problem. Moreover, in patent document 1, when the alicyclic tetracarboxylic dianhydride is used, the polyimide which improved heat resistance compared with the chain | strand-shaped thing is obtained. However, although such a polyimide film has a dielectric constant at 10 GHz of 3.2 or less, the dielectric loss tangent exceeds 0.01, and the dielectric properties have not been sufficient.

  In order to improve the dielectric characteristics, a copper-clad laminate in which the imide group concentration of the polyimide layer in contact with the copper foil forming the conductor circuit is controlled has been proposed (Patent Document 2). According to Patent Document 2, although the dielectric property can be controlled by the combination of the surface roughness Rz of the copper foil and the polyimide layer having a low imide group concentration on the surface in contact with the copper foil, the control has a limit, and the transmission property It was not satisfactory enough.

JP 2004-358916 A Japanese Patent No. 5031639

  An object of the present invention is to provide a copper-clad laminate, a printed wiring board, and a method for using the same, which can cope with high frequencies associated with downsizing and high performance of electronic devices.

  In order to solve the above-mentioned problems, the present inventors pay attention to the skin effect in copper foil, use copper foil having a specific surface state as a conductor layer, and use polyimide having specific dielectric characteristics as an insulating layer. As a result, it has been found that a circuit board such as an FPC excellent in transmission characteristics in a high frequency region can be obtained, and the present invention has been completed.

That is, the copper clad laminate of the present invention includes a polyimide insulating layer and a copper foil on at least one surface of the polyimide insulating layer. In the copper clad laminate of the present invention, the polyimide insulating layer has the following configurations Ia and Ib:
Ia) Thermal expansion coefficient is in the range of 0 ppm / K or more and 30 ppm / K or less;
Ib) The following formula (i),
_{E 1 = √ε 1 × Tanδ 1} ··· (i)
[Where ε ₁ represents the dielectric constant at 3 GHz by the cavity resonator perturbation method, and Tan δ ₁ represents the dielectric loss tangent at 3 GHz by the cavity resonator perturbation method]
Is calculated based on, E ₁ value is an index showing the dielectric properties is less than 0.009;
Further, the copper foil has the following configuration c:
c) The root mean square roughness (Rq) of the surface in contact with the polyimide insulating layer is in the range of 0.05 μm or more and less than 0.5 μm;
It has.

  In the copper clad laminate of the present invention, the dielectric constant may be 3.1 or less, and the dielectric loss tangent may be less than 0.005.

  In the copper clad laminate of the present invention, the arithmetic average height (Ra) of the surface of the copper foil in contact with the polyimide insulating layer may be 0.2 μm or less.

  In the copper clad laminate of the present invention, the ten-point average roughness (Rz) of the surface of the copper foil in contact with the polyimide insulating layer may be 1.5 μm or less.

  In the copper clad laminate of the present invention, the polyimide insulating layer may have a dielectric constant at 10 GHz of 3.0 or less and a dielectric loss tangent of 0.005 or less.

  The printed wiring board of the present invention is obtained by processing a copper circuit of any one of the above copper-clad laminates with a wiring circuit.

  In the usage method of the printed wiring board of the present invention, the printed wiring board is preferably used in a frequency region within a range of 1 GHz to 40 GHz, and more preferably used in a frequency region within a range of 1 GHz to 20 GHz.

  The copper-clad laminate of the present invention can be used effectively as an electronic material requiring high-speed signal transmission because the dielectric property of the polyimide insulating layer can be effectively utilized by suppressing an increase in resistance due to the skin effect of the copper foil. Can be used.

It is a graph which shows the result of Example 1 and Reference Examples 1-3. It is a graph which shows the result of simulation (1)-(6). It is a graph which shows the result of simulation (7)-(12).

  Embodiments of the present invention will be described below.

<Copper-clad laminate>
The copper clad laminate of this embodiment is a copper clad laminate having a polyimide insulating layer and a copper foil layer on at least one surface of the polyimide insulating layer, and the copper foil is provided only on one side of the polyimide insulating layer. It may be a single-sided copper-clad laminate provided with a double-sided copper-clad laminate provided with copper foil on both sides of the polyimide insulating layer. The double-sided copper-clad laminate is formed by, for example, forming a single-sided copper-clad laminate and then pressing the polyimide insulation layers against each other and pressing them by hot pressing. It can be obtained by pressing and forming a foil.

<Polyimide insulation layer>
Examples of the polyimide forming the polyimide resin layer include heat-resistant resins having an imide group in the structure such as polyamideimide, polybenzimidazole, polyimide ester, polyetherimide, polysiloxaneimide, and so on.

The polyimide insulation layer has a thermal linear expansion coefficient in the range of 0 to 30 ppm / K. By controlling the coefficient within such a range, warpage and dimensional stability degradation when forming a copper clad laminate are suppressed. can do. The polyimide insulating layer has a single layer or a plurality of polyimide layers, but the low thermal expansion polyimide layer is preferably applied as a base film layer (main layer of the insulating resin layer). Specifically, the thermal linear expansion coefficient is in the range of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K), preferably in the range of 1 × 10 ^{−6 to} 25 × 10 ⁻⁶ (1 / K). More preferably, when a low thermal expansion polyimide layer in the range of 15 × 10 ^{−6 to} 25 × 10 ⁻⁶ (1 / K) is applied to the base film layer, a great effect can be obtained. On the other hand, the polyimide layer exceeding the thermal linear expansion coefficient is also preferably applied as an adhesive layer with the copper foil layer. As a polyimide that can be suitably used as such an adhesive polyimide layer, a glass transition temperature of, for example, 350 ° C. or lower is preferable, and a glass transition temperature in the range of 200 to 320 ° C. is more preferable.

  The thickness of the polyimide insulating layer may be, for example, in the range of 6 to 50 μm, and preferably in the range of 9 to 45 μm. If the thickness of the polyimide insulating layer is less than 6 μm, there is a risk of wrinkles occurring during transport in the manufacture of copper-clad laminates, etc., whereas if the thickness of the polyimide insulating layer exceeds 50 μm, the copper-clad laminate There may be a problem in dimensional stability, flexibility, etc. during the production of the plate. In addition, what is necessary is just to make it the total thickness in the said range, when forming a polyimide insulating layer from several polyimide layers.

(Dielectric properties)
In order to ensure the transmission characteristics in the high frequency range when used for a circuit board such as a flexible circuit board (hereinafter, may be referred to as “FPC”), the polyimide insulating layer has the above formula (i ) based on the calculated the, _{E 1} value is an index showing the dielectric characteristics of 3GHz by a cavity resonator perturbation method is less than 0.009, preferably well in the range of 0.0025 to 0.007, more preferably Is preferably in the range of 0.0025 to 0.006. E ₁ values exceeds the upper limit, when used on a circuit board such as an FPC, is likely to occur inconveniences such as loss of electrical signals on the transmission path of the RF signal.

(Dielectric constant and dielectric loss tangent)
When the polyimide insulating layer is used for a circuit board such as an FPC, a dielectric constant (ε _{1) at} 3 GHz is used in order to obtain a transmission loss equivalent to a copper-clad laminate produced using a liquid crystal polymer in the 1 to 40 HGz band. ) Is preferably 3.1 or less, and the dielectric loss tangent (Tanδ ₁ ) is preferably less than 0.005. When the dielectric constant at 3 GHz of the polyimide insulating layer exceeds 3.1 and the dielectric loss tangent is 0.005 or more, an inconvenience of loss of an electric signal is likely to occur when used for a circuit board such as an FPC.

  The polyimide insulating layer preferably has a dielectric loss tangent of less than 0.005 at 3 GHz in order to reduce the transmission loss to the same level as the liquid crystal polymer when used on a circuit board such as an FPC. When the dielectric loss tangent at 3 GHz of the polyimide insulating layer is 0.005 or more, a loss of an electrical signal occurs on a high-frequency signal transmission path when used for a circuit board such as an FPC.

  Further, when the polyimide insulating layer is used for a circuit board such as an FPC, the dielectric constant at 10 GHz is preferably 3.0 or less and the dielectric loss tangent is 0 in order to reduce the transmission loss to the same level as the liquid crystal polymer. It is good that it is 0.005 or less. By controlling the dielectric characteristics of the polyimide insulating layer within such a range, transmission loss can be suppressed on the transmission path of the high-frequency signal when used for a circuit board such as an FPC.

  From the viewpoint of easy control of the thickness and physical properties of the polyimide insulating layer, it is preferable to use a so-called cast (coating) method in which the polyamic acid solution is directly applied onto the copper foil and then dried and cured by heat treatment. Moreover, when making a polyimide insulating layer into multiple layers, it can form by apply | coating another polyamic-acid solution sequentially on the polyamic-acid solution which consists of a different structural component. When the polyimide insulating layer is composed of a plurality of layers, the polyimide precursor resin having the same configuration may be used twice or more.

  A polyimide particularly suitable for forming a polyimide insulating layer includes an acid anhydride component containing an aromatic tetracarboxylic acid anhydride, and the two terminal carboxylic acid groups of dimer acid substituted with primary aminomethyl groups or amino groups. A polyimide obtained by reacting a dimer acid diamine and an aromatic diamine containing diamine component, wherein the dimer acid diamine is in the range of 4 to 40 mol% with respect to the total diamine component. Some are preferred.

  Such a polyimide is preferably a polyimide having a structural unit represented by the following general formulas (1) and (2).

［式中、Ａｒは芳香族テトラカルボン酸無水物から誘導される４価の芳香族基、Ｒ_１はダイマー酸型ジアミンから誘導される２価のダイマー酸型ジアミン残基、Ｒ_２は芳香族ジアミンから誘導される２価の芳香族ジアミン残基をそれぞれ表し、ｍ、ｎは各構成単位の存在モル比を示し、ｍは０．０４〜０．４の範囲内、ｎは０．６〜０．９６の範囲内である］

[Wherein Ar is a tetravalent aromatic group derived from an aromatic tetracarboxylic anhydride, R ₁ is a divalent dimer acid diamine residue derived from a dimer acid diamine, and R ₂ is aromatic. Each represents a divalent aromatic diamine residue derived from diamine, m and n represent the molar ratio of each constituent unit, m is in the range of 0.04 to 0.4, and n is 0.6 to Within the range of 0.96]

  Examples of the group Ar include those represented by the following formula (3) or formula (4).

［式中、Ｗは単結合、炭素数１〜１５の２価の炭化水素基、−Ｏ−、−Ｓ−、−ＣＯ−、−ＳＯ−、−ＳＯ_２−、−ＮＨ−若しくは−ＣＯＮＨ−から選ばれる２価の基を示す］

[Wherein, W is a single bond, a divalent hydrocarbon group having 1 to 15 carbon atoms, —O—, —S—, —CO—, —SO—, —SO ₂ —, —NH— or —CONH— Represents a divalent group selected from

  In particular, from the viewpoint of reducing the polar group of polyimide and improving the dielectric properties, the group Ar is represented by the formula (3) or W in the formula (4) is a single bond and a divalent carbon atom having 1 to 15 carbon atoms. What is represented by a hydrogen group, -O-, -S-, -CO- is preferable, and W in formula (3) or formula (4) is a single bond and a divalent hydrocarbon having 1 to 15 carbon atoms. A group represented by —CO— is more preferable.

  In addition, the structural unit represented by the general formulas (1) and (2) may be present in the homopolymer or may be present as a structural unit of the copolymer. In the case of a copolymer having a plurality of structural units, it may exist as a block copolymer or a random copolymer.

Since polyimide is generally produced by reacting an acid anhydride with a diamine, a specific example of polyimide can be understood by explaining the acid anhydride and diamine. In the above general formulas (1) and (2), the group Ar can be referred to as an acid anhydride residue, and the groups R ₁ and R ₂ can be referred to as diamine residues. And diamine.

  Examples of the acid anhydride having the group Ar as a residue include pyromellitic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetra Preferred examples include carboxylic dianhydride and 4,4′-oxydiphthalic anhydride. Examples of the acid anhydride include 2,2 ′, 3,3′-, 2,3,3 ′, 4′- or 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2, 3 ', 3,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,3 ', 3,4'-diphenyl ether tetracarboxylic dianhydride Bis (2,3-dicarboxyphenyl) ether dianhydride, 3,3``, 4,4 ''-, 2,3,3``, 4 ''-or 2,2 '', 3 , 3 ''-p-terphenyltetracarboxylic dianhydride, 2,2-bis (2,3- or 3,4-dicarboxyphenyl) -propane dianhydride, bis (2,3- or 3.4- Dicarboxyphenyl) methane dianhydride, bis (2,3- or 3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3- or 3,4-dicarboxyphenyl) ethane Anhydride, 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic acid Dianhydride 2,2-bis (3,4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7- Hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3, 6,7- (or 1,4,5,8-) tetrachloronaphthalene-1,4,5,8- (or 2,3,6,7-) tetracarboxylic dianhydride, 2,3,8 , 9-, 3,4,9,10-, 4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic dianhydride, cyclopentane-1,2,3,4- Tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5 -Tetracarboxylic acid Anhydride, 4,4'-bis (2,3-dicarboxyphenoxy) diphenylmethane dianhydride and the like.

The group R ₁ is a divalent dimer acid diamine residue derived from dimer acid diamine. The dimer acid type diamine is a diamine obtained by substituting the primary aminomethyl group (—CH ₂ —NH ₂ ) or the amino group (—NH ₂ ) of the two terminal carboxylic acid groups (—COOH) of the dimer acid. Means.

  Dimer acid is a known dibasic acid obtained by an intermolecular polymerization reaction of an unsaturated fatty acid, and its industrial production process is almost standardized in the industry, and an unsaturated fatty acid having 11 to 22 carbon atoms is converted into a clay catalyst. It is obtained by dimerization with the above. The dimer acid obtained industrially is mainly composed of a dibasic acid having 36 carbon atoms obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms such as oleic acid or linoleic acid, depending on the degree of purification. , Containing any amount of monomeric acid (18 carbon atoms), trimer acid (54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms. In the present invention, it is preferable to use dimer acid having a dimer acid content increased to 90% by weight or more by molecular distillation. In addition, although a double bond remains after the dimerization reaction, in the present invention, a dimer acid that is further reduced in the degree of unsaturation by hydrogenation reaction is included.

As a feature of the dimer acid diamine, a characteristic derived from the skeleton of the dimer acid can be imparted. That is, since the dimer acid type diamine is a macromolecular aliphatic having a molecular weight of about 560 to 620, the molecular molar volume can be increased and the polar groups of the polyimide can be relatively reduced. Such a feature of the dimer acid type diamine is considered to contribute to improving the dielectric properties while suppressing a decrease in the heat resistance of the polyimide. In addition, since it has two freely moving hydrophobic chains having 7 to 9 carbon atoms and two chain-like aliphatic amino groups having a length close to 18 carbon atoms, not only gives flexibility to the polyimide, Since polyimide can be made into a non-target chemical structure or a non-planar chemical structure, it is thought that the dielectric constant of polyimide can be reduced.

  The charging amount of the dimer acid type diamine is in the range of 4 to 40 mol%, preferably in the range of 4 to 30 mol%, more preferably in the range of 4 to 15 mol% with respect to the total diamine component. When the dimer acid type diamine is less than 4 mol%, the dielectric properties of the polyimide tend to be lowered, and when it exceeds 40 mol%, the heat resistance tends to be deteriorated due to a decrease in the glass transition temperature of the polyimide.

  The dimer acid type diamine is commercially available. For example, PRIAMINE 1073 (trade name) manufactured by Croda Japan, PRIAMINE 1074 (trade name), Versamine 551 (trade name), Versamine 552 (product) manufactured by Cognis Japan. Name).

Examples of the group R ₂ include those represented by the following formulas (5) to (7).

［式（５）〜式（７）において、Ｒ_３は独立に炭素数１〜６の１価の炭化水素基又はアルコキシ基を示し、Ｚは単結合、炭素数１〜１５の２価の炭化水素基、−Ｏ−、−Ｓ−、−ＣＯ−、−ＳＯ−、−ＳＯ_２−、−ＮＨ−若しくは−ＣＯＮＨ−から選ばれる２価の基を示し、ｎ_１は独立に０〜４の整数を示す］

[In Formula (5)-Formula (7), R < ₃ > shows a C1-C6 monovalent hydrocarbon group or an alkoxy group independently, Z is a single bond and C1-C15 bivalent carbonization. A divalent group selected from a hydrogen group, —O—, —S—, —CO—, —SO—, —SO ₂ —, —NH— or —CONH—, wherein n ₁ is independently 0-4; Indicates an integer]

In particular, from the viewpoint of reducing the polar groups of polyimide and improving the dielectric properties, the group R ₂ includes Z in the formulas (5) to (7) as a single bond and a divalent carbon atom having 1 to 15 carbon atoms. It is preferable that the hydrogen group, R ₃ is a monovalent hydrocarbon group having 1 to 6 carbon atoms, and n ₁ is an integer of 0 to 4.

Examples of the diamine having the group R ₂ as a residue include 4,4′-diaminodiphenyl ether, 2′-methoxy-4,4′-diaminobenzanilide, 1,4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'- Dihydroxy-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 2,2-bis- [4- (3-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] Sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy)] biphenyl, bis [4- (3-aminophenoxy) biphenyl, bis [1- (4-aminophenoxy) )] Biphenyl, bis [1- (3-aminophenoxy)] biphenyl, bi [4- (4-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) ) Phenyl] ether, bis [4- (4-aminophenoxy)] benzophenone, bis [4- (3-aminophenoxy)] benzophenone, bis [4,4 '-(4-aminophenoxy)] benzanilide, bis [4 , 4 '-(3-aminophenoxy)] benzanilide, 9,9-bis [4- (4-aminophenoxy) phenyl] fluorene, 9,9-bis [4- (3-aminophenoxy) phenyl] fluorene, 2 , 2-bis- [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis- [4- (3-aminophenoxy) phenyl] hexafluoropropane, 4,4'-methylenedi-o- Toluidine, 4,4'-methylenedi-2,6-xy Gin, 4,4'-methylene-2,6-diethylaniline, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenyl Ethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylsulfone, 3,3'- Diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 3,3-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diamino Biphenyl, 3,3'-dimethoxybenzidine, 4,4 ''-diamino-p-terphenyl, 3,3 ''-diamino-p-terphenyl, m-phenylenediamine, p-phenylenediamine, 2,6- Diaminopyridine, 1,4-bis ( 4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 4,4 '-[1,4-phenylenebis (1-methylethylidene)] bisaniline, 4,4'-[1,3 -Phenylenebis (1-methylethylidene)] bisaniline, bis (p-aminocyclohexyl) methane, bis (p-β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene P-bis (2-methyl-4-aminopentyl) benzene, p-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4 -Bis (β-amino-t-butyl) toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine Amine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, etc. It is done.

  Based on the dielectric properties of polyimide, the aromatic tetracarboxylic acid anhydride suitably used for the preparation of the polyimide precursor is, for example, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA). 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride (BTDA), 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA), pyromellitic dianhydride (PMDA). Among them, particularly preferred acid anhydrides include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride ( BTDA) and the like. These aromatic tetracarboxylic acid anhydrides can be blended in combination of two or more.

In addition to the above acid anhydrides, siloxane tetracarboxylic dianhydrides can also be suitably used. Examples thereof include siloxane tetracarboxylic dianhydrides represented by the following general formula (8).

［式（８）中、Ｒ、Ｒ’は独立に３価の炭素数１〜４の脂肪族基又は芳香族基を示し、Ｒ_４〜Ｒ_７は独立に、置換基を有していてもよい炭素数１〜６の炭化水素基を示し、ｎは１〜５０の整数を示すが、平均繰り返し数は１〜２０である］

[In Formula (8), R and R ′ each independently represents a trivalent aliphatic group having 1 to 4 carbon atoms or an aromatic group, and R _{4 to} R ₇ may independently have a substituent. A good hydrocarbon group having 1 to 6 carbon atoms, n represents an integer of 1 to 50, and the average number of repetitions is 1 to 20]

In addition to the above acid anhydrides, siloxane tetracarboxylic dianhydrides can also be suitably used. Examples thereof include siloxane tetracarboxylic dianhydrides represented by the following general formula (9).

［式（９）中、Ｒ_１１及びＲ_１２は独立に２価の炭化水素基を示し、Ｒ_４〜Ｒ_７は独立に、置換基を有していてもよい炭素数１〜６の炭化水素基を示し、ｎは１〜５０の整数を示すが、平均繰り返し数は１〜２０である］

[In Formula (9), R ₁₁ and R ₁₂ independently represent a divalent hydrocarbon group, and R _{4 to} R ₇ independently represent a hydrocarbon having 1 to 6 carbon atoms which may have a substituent. And n represents an integer of 1 to 50, but the average number of repetitions is 1 to 20]

  In addition, based on the dielectric properties of polyimide, examples of aromatic diamines suitably used for the preparation of polyimide precursors include 2,2-bis (4-aminophenoxyphenyl) propane (BAPP), 2,2′-. Divinyl-4,4′-diaminobiphenyl (VAB), 2,2′-dimethyl-4,4′-diaminobiphenyl (m-TB), 2,2′-diethyl-4,4′-diaminobiphenyl, 2, 2 ′, 6,6′-tetramethyl-4,4′-diaminobiphenyl, 2,2′-diphenyl-4,4′-diaminobiphenyl, 9,9-bis (4-aminophenyl) fluorene, etc. Can do. Among them, particularly preferred diamine components are 2,2-bis (4-aminophenoxyphenyl) propane (BAPP), 2,2′-divinyl-4,4′-diaminobiphenyl (VAB), 2,2′- Examples thereof include dimethyl-4,4′-diaminobiphenyl (m-TB). These aromatic diamines can be blended in combination of two or more.

  Each of the acid anhydrides and diamines may be used alone or in combination of two or more. In addition, other diamines and acid anhydrides not included in the above general formulas (1) and (2) can be used together with the above acid anhydrides or diamines. In this case, use of other acid anhydrides or diamines is also possible. The ratio is preferably 10 mol% or less, more preferably 5 mol% or less. By selecting the types of acid anhydrides and diamines, and the respective molar ratios when using two or more acid anhydrides or diamines, the thermal expansibility, adhesiveness, glass transition temperature, etc. can be controlled. .

  The polyimide having the structural units represented by the general formulas (1) and (2) is obtained by reacting the aromatic tetracarboxylic acid anhydride, dimer acid type diamine and aromatic diamine in a solvent to produce a precursor resin. It can be produced by heating and ring closure. For example, it is a polyimide precursor by dissolving an acid anhydride component and a diamine component in an approximately equimolar amount in an organic solvent and stirring and polymerizing at a temperature in the range of 0 to 100 ° C. for 30 minutes to 24 hours. A polyamic acid is obtained. In the reaction, the reaction components are dissolved so that the precursor to be produced is in the range of 5 to 30% by weight, preferably in the range of 10 to 20% by weight in the organic solvent. Examples of the organic solvent used for the polymerization reaction include N, N-dimethylformamide, N, N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, and dioxane. , Tetrahydrofuran, diglyme, triglyme and the like. Two or more of these solvents can be used in combination, and further, aromatic hydrocarbons such as xylene and toluene can be used in combination. The amount of such organic solvent used is not particularly limited, but the amount used is such that the concentration of the polyamic acid solution (polyimide precursor solution) obtained by the polymerization reaction is about 5 to 30% by weight. It is preferable to adjust and use.

  The synthesized precursor is usually advantageously used as a reaction solvent solution, but can be concentrated, diluted, or replaced with another organic solvent if necessary. Moreover, since a precursor is generally excellent in solvent solubility, it is advantageously used. The method for imidizing the precursor is not particularly limited, and for example, heat treatment such as heating in the solvent at a temperature within the range of 80 to 400 ° C. for 1 to 24 hours is suitably employed.

The polyimide insulating layer may contain an inorganic filler in the polyimide layer as necessary. Specific examples include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, and calcium fluoride. These may be used alone or in combination of two or more.

<Copper foil>
In the copper clad laminate of the present embodiment, the copper foil has a mean square roughness (Rq) of the surface in contact with the polyimide insulating layer in the range of 0.05 μm or more and less than 0.5 μm, preferably 0.1 μm or more. The range of 0.4 μm or less is preferable. The root mean square roughness (Rq) defined here is based on JIS B0601: 2001. The material of the copper foil may be a copper alloy.

The copper foil used for the copper clad laminated board of this Embodiment will not be specifically limited if the said characteristic is satisfy | filled, The commercially available copper foil can be used. Specific examples of the rolled copper foil include BHY-22B-T (trade name) and GHY5-93F-T (trade name) manufactured by JX Nippon Mining & Metals Co., Ltd. Are F1-WS (trade name) manufactured by Furukawa Electric Co., Ltd., HLS (trade name), HLS-Type2 (trade name), HLB (trade name), JX Nippon Mining & Metals Examples thereof include AMFN (trade name) manufactured by Co., Ltd.

  When a high-frequency signal is supplied to the signal wiring, current flows only on the surface of the signal wiring, the effective cross-sectional area through which the current flows decreases, the DC resistance increases, and the signal attenuates (skin effect) ) By reducing the surface roughness of the surface of the copper foil in contact with the polyimide insulating layer, an increase in the resistance of the signal wiring due to the skin effect can be suppressed. However, if the surface roughness is lowered to satisfy the electrical performance requirement standard, the adhesive strength (peel strength) between the copper foil and the polyimide insulating layer becomes weak. Therefore, it is important to control the root mean square roughness (Rq) as a surface roughness parameter from the viewpoint of satisfying electrical performance requirements and ensuring adhesion with the polyimide insulating layer. That is, from the results of the simulation test described later, the root mean square roughness (Rq) is smaller than the other surface roughness indices, with respect to the current flowing on the copper foil surface due to the skin effect, the fine irregularities on the copper foil surface. It is presumed that it reflects the impact on the project more accurately. Accordingly, by using the root mean square roughness (Rq) as an index of the surface roughness of the surface in contact with the polyimide insulation layer in the copper foil, and by defining this mean square roughness (Rq) within the above range, polyimide insulation It is possible to simultaneously satisfy the requirements that are in a trade-off relationship between securing adhesion to the layer and suppressing an increase in wiring resistance.

  Moreover, as for the surface roughness of the surface which contacts the insulating resin layer of copper foil, it is preferable that arithmetic mean height Ra is 0.2 micrometer or less, and it is preferable that ten-point average roughness Rz is 1.5 micrometers or less.

<Printed wiring board>
The printed wiring board according to the present embodiment is a printed wiring board according to an embodiment of the present invention by forming a wiring layer by processing the copper foil of the copper-clad laminate according to the present embodiment into a pattern by a conventional method. A wiring board can be manufactured.

  Hereinafter, a method for manufacturing a printed wiring board according to the present embodiment will be specifically described by taking the case of a cast method as an example.

First, the manufacturing method of a copper clad laminated board can include the following processes (1)-(3).
Step (1):
Step (1) is a step of obtaining a resin solution of polyamic acid that is a precursor of polyimide used in the present embodiment.

Step (2):
Step (2) is a step of applying a polyamic acid resin solution on the copper foil to form a coating film. The copper foil can be used in the form of a cut sheet, a roll, or an endless belt. In order to obtain productivity, it is efficient to use a roll-like or endless belt-like form so that continuous production is possible. Furthermore, the copper foil is preferably in the form of a roll that is formed in a long length from the viewpoint of more greatly improving the effect of improving the wiring pattern accuracy in the printed wiring board.

  The coating film can be formed by applying a polyamic acid resin solution directly on a copper foil and then drying. The method of applying is not particularly limited, and it is possible to apply with a coater such as a comma, die, knife, lip or the like.

  The polyimide layer may be a single layer or a plurality of layers. In the case where a plurality of polyimide layers are used, other precursors can be sequentially applied on the precursor layers made of different components. When the precursor layer is composed of three or more layers, the precursor having the same configuration may be used twice or more. A two-layer or a single layer having a simple layer structure is preferable because it can be advantageously obtained industrially. The thickness of the precursor layer (after drying) is, for example, in the range of 3 to 100 μm, preferably in the range of 3 to 50 μm.

  When making a polyimide layer into multiple layers, it is preferable to form a layer of a precursor so that the polyimide layer which touches copper foil may become a thermoplastic polyimide layer. By using thermoplastic polyimide, the adhesion to the copper foil can be improved. Such a thermoplastic polyimide preferably has a glass transition temperature (Tg) of 360 ° C. or lower, more preferably 200 to 320 ° C.

  It is also possible to once imidize a single layer or a plurality of precursor layers into a single layer or a plurality of polyimide layers, and further form a precursor layer thereon.

Step (3):
Step (3) is a step of forming a polyimide insulating layer by heat-treating the coating film to imidize it. The imidization method is not particularly limited, and for example, heat treatment such as heating for 1 to 60 minutes under a temperature condition in the range of 80 to 400 ° C. is suitably employed. In order to suppress the oxidation of the metal layer, heat treatment in a low oxygen atmosphere is preferable. Specifically, the heat treatment is performed in an inert gas atmosphere such as nitrogen or a rare gas, in a reducing gas atmosphere such as hydrogen, or in a vacuum. Is preferred. By the heat treatment, the polyamic acid in the coating film is imidized to form polyimide.

  As described above, a copper clad laminate having a polyimide layer (single layer or a plurality of layers) and a copper foil can be produced.

  The circuit board manufacturing method can further include the following step (4) in addition to the above steps (1) to (3).

Step (4):
Step (4) is a step of forming a wiring layer by patterning the copper foil of the copper clad laminate. In this step, a copper foil is etched into a predetermined shape to form a pattern, and a printed wiring board is obtained by processing into a wiring layer. Etching can be performed by any method using, for example, photolithography.

  In the above description, only the characteristic steps of the printed wiring board manufacturing method have been described. That is, when manufacturing a printed wiring board, processes other than the above normally performed, for example, processes such as through-hole processing in the previous process, terminal plating in the subsequent process, and external processing can be performed according to a conventional method.

  As described above, by using the polyimide insulating layer and the copper foil of the present embodiment, a copper-clad laminate having excellent transmission characteristics can be formed. In addition, by using the polyimide insulating layer and the copper foil of this embodiment mode, electrical signal transmission characteristics can be improved and reliability can be improved in a circuit board typified by FPC.

  The features of the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to the examples. In the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Measurement of coefficient of thermal expansion (CTE)]
The coefficient of thermal expansion was 30 ° C. to 250 ° C. with a constant temperature increase rate while applying a 5.0 g load using a thermomechanical analyzer (trade name: 4000SA) made of a polyimide film having a size of 3 mm × 20 mm. Then, the temperature was further maintained at that temperature for 10 minutes, followed by cooling at a rate of 5 ° C./minute, and an average thermal expansion coefficient (linear thermal expansion coefficient) from 240 ° C. to 100 ° C. was determined.

[Measurement of glass transition temperature (Tg)]
The glass transition temperature is 5 mm × 20 mm using a viscoelasticity measuring device (DMA: manufactured by TA Instruments Co., Ltd., trade name: RSA3). The temperature at which the elastic modulus change was maximum (the tan δ change rate was the largest) was evaluated as the glass transition temperature.

[Measurement of peel strength]
Peel strength was measured using a tensilon tester (trade name: Strograph VE-10, manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the double-sided tape was applied to the resin layer side of a 1 mm wide sample (laminate composed of substrate / resin layer). Was fixed to the aluminum plate, and the force for peeling the resin layer and the substrate in the 180 ° direction at a speed of 50 mm / min was determined.

[Measurement of dielectric constant and dissipation factor]
The dielectric constant and dielectric loss tangent are measured using a cavity resonator perturbation method dielectric constant evaluation apparatus (manufactured by Agilent, trade name: Vector Network Analyzer E 8363B), and the dielectric constant and dielectric of the resin sheet (cured resin sheet) at a predetermined frequency. Tangent was measured. In addition, the resin sheet used for the measurement was left for 24 hours under the conditions of temperature; 24-26 ° C., humidity: 45-55%.

[Measurement of surface roughness of copper foil]
1) Measurement of root mean square roughness (Rq) Using a stylus type surface roughness meter (trade name: Surfcorder ET-3000, manufactured by Kosaka Laboratory Ltd.), Force: 100 μN, Speed: 20 μm, Range: 800 μm It was determined according to the measurement conditions. The surface roughness was calculated by a method based on JIS-B0601: 2001.
2) Measurement of arithmetic average height (Ra) Using a stylus type surface roughness meter (trade name: Surfcorder ET-3000, manufactured by Kosaka Laboratory Ltd.), Force: 100 μN, Speed: 20 μm, Range: 800 μm It was determined according to the measurement conditions. The surface roughness was calculated by a method based on JIS-B0601: 1994.
3) Measurement of 10-point average roughness (Rz) Using a stylus type surface roughness meter (trade name; Surfcorder ET-3000, manufactured by Kosaka Laboratory Ltd.), Force: 100 μN, Speed: 20 μm, Range: 800 μm It was determined according to the measurement conditions. The surface roughness was calculated by a method based on JIS-B0601: 1994.

[Evaluation of transmission characteristics]
The transmission characteristics were evaluated by evaluating the transmission characteristics on the circuit processed side (transmission line side) using an evaluation sample obtained by processing a circuit of a copper-clad laminate and processing a microstrip line with a characteristic impedance of 50Ω. Evaluation was performed at S21 (insertion loss) by measuring S parameters in a predetermined frequency region with a vector network analyzer calibrated by the SOLT method (SHORT-OPEN-LOOD-Thru).

Abbreviations used in Examples and Comparative Examples indicate the following compounds.
(A) Polyimide raw material DDA: Dimer acid type diamine (trade name: PRIAMINE 1074, carbon number: 36, amine value: 205 mgKOH / g, content of dimer component: 95% by weight or more)
m-TB: 2,2′-dimethyl-4,4′-diaminobiphenyl BAPP: 2,2-bis (4-aminophenoxyphenyl) propane TPE-R: 1,3-bis (4-aminophenoxy) benzene wander Min: 4,4′-diaminodicyclohexylmethane BAFL: 9,9-bis (4-aminophenyl) fluorene TFMB: 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl PMDA: pyromellitic acid Dianhydride BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride DMAc: N, N-dimethylacetamide

(B) Copper foil Copper foil (1): Electrolytic copper foil, thickness: 12 μm, surface roughness Rq on the resin laminate side: 0.14 μm, Rz: 0.64 μm, Ra: 0.10 μm)
Copper foil (2): Electrolytic copper foil, thickness: 12 μm, surface roughness Rq on the resin laminate side: 0.19 μm, Rz: 1.06 μm, Ra: 0.16 μm)
Copper foil (3): Electrolytic copper foil, thickness: 12 μm, surface roughness Rq on the resin laminate side: 0.27 μm, Rz: 1.36 μm, Ra: 0.21 μm)
Copper foil (4): electrolytic copper foil, thickness: 12 μm, surface roughness Rq on the resin lamination side: 0.35 μm, Rz: 1.51 μm, Ra: 0.28 μm)
Copper foil (5): Electrolytic copper foil, thickness 12 μm, surface roughness Rq on the resin laminate side: 0.5 μm, Rz; 1.65 μm, Ra; 0.36 μm)
Copper foil (6): Rolled copper foil, thickness 12 μm, surface roughness Rq on the resin laminate side: 0.24 μm, Rz: 1.30 μm, Ra: 0.18 μm)

Synthesis example 1
Under a nitrogen stream, charge 2.196 g DDA (0.0041 mol), 16.367 g m-TB (0.0771 mol) and 212.5 g DMAc to a 300 ml separable flask and stir at room temperature. And dissolved. Next, 4.776 g of BPDA (0.0162 mol) and 14.161 g of PMDA (0.0649 mol) were added, and the polymerization reaction was continued for 3 hours at room temperature to obtain a polyamic acid solution a. It was. The solution viscosity of the polyamic acid solution a was 26,000 cps.

Synthesis Examples 2-13
Polyamic acid solutions b to m were prepared in the same manner as in Synthesis Example 1 except that the raw material compositions shown in Table 1 and Table 2 were used.

[Production Example 1]
After applying the polyamic acid solution a prepared in Synthesis Example 1 uniformly on one side (surface roughness Rz; 2.1 μm) of an electrolytic copper foil having a thickness of 18 μm so that the thickness after curing is about 25 μm, 120 The solvent was removed by heat drying at ° C. Furthermore, stepwise heat treatment was performed from 120 ° C. to 360 ° C. to complete imidization. About the obtained metal-clad laminated body, the copper foil was etched away using the ferric chloride aqueous solution, and the polyimide film 1 was obtained. In addition, the polyimide which comprises the polyimide film 1 was non-thermoplastic.
The thermal expansion coefficient, glass transition temperature, dielectric constant and dielectric loss tangent of the polyimide film 1 were determined. Table 3 shows the measurement results.

[Production Examples 2 to 6]
Except having used the polyamic-acid solution shown in Table 3, it carried out similarly to the manufacture example 1, and obtained the polyimide films 2-6 of the manufacture examples 2-6. The thermal expansion coefficient (CTE), glass transition temperature, dielectric constant and dielectric loss tangent of the obtained polyimide films 2 to 6 were determined. Table 3 shows the measurement results.

  The results of Production Examples 1 to 6 are summarized in Table 3.

[Production Example 7]
After applying the polyamic acid solution h uniformly on one surface (surface roughness Rz; 1.39 μm) of an electrolytic copper foil having a thickness of 12 μm so that the thickness after curing is about 2 to 3 μm, 85 ° C. to 110 ° C. The solvent was removed by drying by stepwise heat treatment. Next, the polyamic acid solution b was uniformly applied thereon so that the thickness after curing was about 42 to 46 μm, and the solvent was removed by stepwise heat treatment from 85 ° C. to 110 ° C. Furthermore, after the polyamic acid solution h was uniformly applied thereon so that the thickness after curing was about 2 to 3 μm, the solvent was removed by a stepwise heat treatment from 85 ° C. to 110 ° C. Thus, after forming the polyamic acid layer of 3 layers, stepwise heat processing was performed from 120 degreeC to 320 degreeC, imidation was completed, and the metal-clad laminated body 7 was obtained. About the obtained metal-clad laminated body 7, the copper foil was etched away using the ferric chloride aqueous solution, and the polyimide film 7 with a thickness of about 50 micrometers was obtained. The dielectric constant (ε ₁ ) and dielectric loss tangent (Tanδ ₁ ) at 3 GHz of the obtained polyimide film 7 are 3.06 and 0.0029 (E ₁ = 0.0051), respectively, and the dielectric constant and dielectric loss tangent at 10 GHz. Were 2.86 and 0.0036, respectively.

[Example 1]
The polyamic acid solution h was uniformly applied to the copper foil 2 so that the thickness after curing was about 2 to 3 μm, and then dried by stepwise heat treatment from 85 ° C. to 110 ° C. to remove the solvent. Next, the polyamic acid solution b was uniformly applied thereon so that the thickness after curing was about 42 to 46 μm, and the solvent was removed by stepwise heat treatment from 85 ° C. to 110 ° C. Furthermore, after the polyamic acid solution h was uniformly applied thereon so that the thickness after curing was about 2 to 3 μm, the solvent was removed by a stepwise heat treatment from 85 ° C. to 110 ° C. Thus, after forming the polyamic acid layer of 3 layers, stepwise heat processing was performed from 120 degreeC to 320 degreeC, imidation was completed, and copper clad laminated board 1 'was obtained. Copper foil 1 was superposed on the polyimide insulating layer side of the obtained copper-clad laminate 1 ′ and thermocompression bonded for 15 minutes under the conditions of a temperature of 380 ° C. and a pressure of 6.7 MPa to obtain copper-clad laminate 1. The peel strength of the copper foil 1 on the thermocompression bonding side and the polyimide insulating layer in the obtained copper-clad laminate 1 was 0.96 kN / m. Circuit processing was performed with the copper foil 1 side as the ground plane and the copper foil 2 side as the signal plane, and the transmission characteristics were evaluated. The result is shown in FIG.

[Reference Example 1]
A laminate was obtained by thermocompression bonding copper foil 4 on both sides of a commercially available liquid crystal polymer film 1 (thickness: 50 μm). Circuit processing was performed using the copper foils on both sides of the laminate as the ground plane and the signal plane, and the transmission characteristics were evaluated. The result is shown in FIG.

[Reference Example 2]
A laminate was obtained by thermocompression bonding copper foil 5 on both sides of a commercially available liquid crystal polymer film 2 (thickness: 50 μm). Circuit processing was performed using the copper foils on both sides of the laminate as the ground plane and the signal plane, and the transmission characteristics were evaluated. The result is shown in FIG.

[Reference Example 3]
A laminate was obtained by thermocompression bonding copper foil 5 on both sides of a commercially available polyimide film having a thickness of 50 μm (dielectric constant at 3 GHz;> 3.1, dielectric loss tangent at 3 GHz;> 0.005). Circuit processing was performed using the copper foils on both sides of the laminate as the ground plane and the signal plane, and the transmission characteristics were evaluated. The result is shown in FIG.

  The results of Example 1 and Reference Examples 1 to 3 are shown in FIG. From FIG. 1, it is confirmed that Example 1 shows a transmission characteristic equal to or higher than that in the frequency range of 1 to 20 GHz in comparison with Reference Example 1.

[Example 2]
The polyamic acid solution h was uniformly applied to the copper foil 3 so that the thickness after curing was about 2 to 3 μm, and then dried by stepwise heat treatment from 85 ° C. to 110 ° C. to remove the solvent. Next, the polyamic acid solution b was uniformly applied thereon so that the thickness after curing was about 42 to 46 μm, and the solvent was removed by stepwise heat treatment from 85 ° C. to 110 ° C. Furthermore, after the polyamic acid solution h was uniformly applied thereon so that the thickness after curing was about 2 to 3 μm, the solvent was removed by a stepwise heat treatment from 85 ° C. to 110 ° C. After forming the three polyamic acid layers in this manner, stepwise heat treatment was performed from 120 ° C. to 320 ° C. to complete imidization, and a copper-clad laminate 2 ′ was obtained. The copper foil 1 was superposed on the polyimide insulating layer side of the obtained copper-clad laminate 2 ′ and thermocompression bonded for 15 minutes under the conditions of a temperature of 380 ° C. and a pressure of 6.7 MPa to obtain a copper-clad laminate 2. The peel strength of the copper foil 1 and the polyimide insulating layer on the thermocompression bonding side in the obtained copper-clad laminate 2 was 0.96 kN / m. Circuit processing was performed using the copper foil 3 side as a ground surface and the copper foil 1 side as a signal surface, and transmission characteristics were evaluated. The result is shown in FIG.

[Example 3]
In the same manner as in Example 2, a copper-clad laminate 3 was obtained. Circuit processing was performed using the copper foil 1 side as the ground plane and the copper foil 3 side as the signal plane, and the transmission characteristics were evaluated. The result is shown in FIG.

[Simulation test]
Next, the result of the simulation test confirming the effect of the present invention will be described. FIG. 2 shows the results when the dielectric constant and dielectric loss tangent at 3 GHz of the polyimide insulating layer are fixed to 3.0 and 0.003, respectively, and Rq is changed from 0 to 1.0. Further, FIG. 3 shows the results when the dielectric constant and dielectric loss tangent at 3 GHz of the polyimide insulating layer are fixed to 3.4 and 0.006, respectively, and Rq is changed from 0 to 1.0. In the simulation test, Rq of the ground plane and the signal plane are set to be the same.
Simulation (1) and (7): Rq = 0 μm
Simulations (2) and (8): Rq = 0.1 μm
Simulations (3) and (9): Rq = 0.2 μm
Simulations (4) and (10): Rq = 0.3 μm
Simulation (5) and (11): Rq = 0.5 μm
Simulations (6) and (12): Rq = 1.0 μm

  The results of Examples 2 and 3, simulations (1) to (6) are shown in FIG. 2, and the results of simulations (7) to (12) are shown in FIG. From FIG. 2, in comparison with Examples 2 and 3 and simulations (1) to (4) in which Rq is less than 0.5 μm, in simulations (5) and (6) where Rq is 0.5 μm or more, transmission loss Is confirmed to be large. In addition, it is confirmed from FIG. 3 that the transmission characteristics are improved in a substantially proportional relationship as the value of Rq decreases, but from FIG. 2, there is a slight gap between simulations (4) and (5). It is confirmed. Therefore, it is considered that there is a synergistic effect between the dielectric characteristics of the polyimide insulating layer and the surface roughness Rq of the copper foil.

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment, A various deformation | transformation is possible.

Claims (7)

A copper-clad laminate comprising a polyimide insulating layer and a copper foil on at least one surface of the polyimide insulating layer,
The polyimide insulating layer has the following configurations Ia and Ib:
Ia) Thermal expansion coefficient is in the range of 0 ppm / K or more and 30 ppm / K or less;
Ib) The following formula (i),
_{E 1 = √ε 1 × Tanδ 1} ··· (i)
[Where ε ₁ represents the dielectric constant at 3 GHz by the cavity resonator perturbation method, and Tan δ ₁ represents the dielectric loss tangent at 3 GHz by the cavity resonator perturbation method]
An E ₁ value, which is an index indicating dielectric characteristics, calculated based on is less than 0.009 , the dielectric constant is 3.1 or less, and the dielectric loss tangent is less than 0.005 ;
Further, the copper foil has the following configuration c:
c) The root mean square roughness (Rq) of the surface in contact with the polyimide insulating layer is in the range of 0.1 μm to 0.4 μm ;
The equipped Rutotomoni,
At least one of the copper foils is a copper clad laminate having a ten-point average roughness (Rz) of 1.06 μm or more on the surface in contact with the polyimide insulating layer . 2. The copper-clad laminate according to claim 1, wherein an arithmetic average height (Ra) of a surface in contact with the polyimide insulating layer of the copper foil is 0.2 μm or less. The copper clad laminate according to claim 1 or 2 , wherein a ten-point average roughness (Rz) of a surface of the copper foil in contact with the polyimide insulating layer is 1.5 µm or less. Wherein is a dielectric constant at 10GHz polyimide insulating layer is 3.0 or less, the copper-clad laminate according to any one of claims 1 to third dielectric loss tangent is 0.005 or less. The printed wiring board formed by carrying out a wiring circuit process of the copper foil of the copper clad laminated board of any one of Claims 1-4 . The usage method of the printed wiring board which uses the printed wiring board of Claim 5 in the frequency area | region within the range of 1 GHz-40 GHz. The usage method of the printed wiring board which uses the printed wiring board of Claim 5 in the frequency area | region within the range of 1 GHz-20 GHz.

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