JP6473028B2 - Copper-clad laminate, printed wiring board and method of using the same - Google Patents

Description

  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 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. Printed circuit board materials use transmission loss due to thinner insulating layers and lower dielectric constants. Reduction 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 the dielectric property and the adhesion between the metal foil, 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 1). According to Patent Document 1, 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 is limited. It was not satisfactory enough.

  Moreover, in order to improve the dielectric characteristics of the insulating resin layer, a copper-clad laminate using a base film formed from an aliphatic diamine as a raw material has been proposed (Patent Document 2). According to Patent Document 2, although the dielectric characteristics of the insulating resin layer are controlled, the transmission characteristics are not fully satisfactory.

Japanese Patent No. 5031639 International Publication WO2014 / 208644

  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 focused on the skin effect in copper foil, and used a copper foil having a specific surface state as a conductor layer, and combined with the copper foil, specific dielectric characteristics. It has been found that a circuit board such as an FPC having excellent transmission characteristics in a high-frequency region can be obtained by using polyimide having an insulating layer for the insulating layer, and the present invention has been completed.

That is, the copper clad laminate of the present invention comprises a polyimide insulating layer and a copper foil laminated on at least one surface of the polyimide insulating layer. And as for the copper clad laminated board of this invention, the said polyimide insulating layer is the following structure Ia-Ic:
Ia) having an adhesive polyimide layer (i) in contact with the surface of the copper foil and a low expansion polyimide layer (ii) laminated directly or indirectly on the adhesive polyimide layer (i);
Ib) The adhesive polyimide layer (i) comprises a polyimide obtained by reacting a tetracarboxylic acid anhydride component and a diamine component, and pyromellitic dianhydride (PMDA) is added to the acid anhydride component. Containing 50 mol% or more, and containing 50 mol% or more of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) with respect to the diamine component;
Ic) The following mathematical formula (a),
_{E 1 = √ε 1 × Tanδ 1} ··· (a)
[Where ε ₁ indicates a dielectric constant at 10 GHz by the cavity resonator perturbation method, and Tan δ ₁ indicates a dielectric loss tangent at 10 GHz by the cavity resonator perturbation method]
The E ₁ value, which is an index indicating dielectric properties, calculated based on the above is less than 0.009;
It has.
In the copper-clad laminate of the present invention, the copper foil further has the following configurations IId and IIe:
IId) The surface in contact with the adhesive polyimide layer (i) is roughened, the ten-point average roughness (Rz) of the copper foil surface is 1.0 μm or less, and the arithmetic average height (Ra) is 0. 2 μm or less;
IIe) The amount of nickel element (Ni) adhering to the surface in contact with the adhesive polyimide layer (i) is 1.4 mg / dm ² or less, and the amount of zinc element (Zn) is 0.01-0.2 mg / Within the range of dm ² , the amount of chromium element (Cr) is within the range of 0.02 to 0.2 mg / dm ² , and the total amount of zinc element and chromium element (Zn + Cr) is 0.03 to 0.3 mg / within the range of dm ² ;
It has.

  In the copper clad laminate of the present invention, the mean square roughness (Rq) of the surface in contact with the polyimide insulating layer in the copper foil may be in the range of 0.05 μm or more and less than 0.5 μm.

  In the copper clad laminate of the present invention, the surface of the copper foil in contact with the adhesive polyimide layer (i) is roughened, and the roughening is measured by scanning electron microscope (SEM) observation of the copper foil cross section. The maximum value of the roughening height of the treatment may be less than 0.6 μm.

In the copper clad laminate of the present invention, the amount of nickel element (Ni) attached to the surface of the copper foil in contact with the adhesive polyimide layer (i) may be 0.01 mg / dm ² or less. The amount of cobalt (Co) may be in the range of 0.01 to 0.5 mg / dm ² , the amount of molybdenum element (Mo) may be in the range of 0.01 to 0.5 mg / dm ² , and the cobalt element And the total amount of molybdenum element (Co + Mo) may be in the range of 0.1 to 0.7 mg / dm ² .

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

  The method for using the printed wiring board of the present invention uses the printed wiring board in a frequency range within a range of 1 GHz to 40 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.

2 is a SEM photograph of a cross section of a copper foil used in Example 1.

  Embodiments of the present invention will be described below.

<Copper-clad laminate>
The copper clad laminate of the present embodiment is a copper clad laminate having a polyimide insulating layer and a copper foil 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. The single-sided copper clad laminated board provided may be sufficient, and the double-sided copper clad laminated board which provided the copper foil on the both sides of the polyimide insulating layer may be sufficient. 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 insulating layer include heat-resistant resins having an imide group in a structure such as polyamideimide, polybenzimidazole, polyimide ester, polyetherimide, polysiloxaneimide, and the like including so-called polyimide.

  The polyimide insulating layer has an adhesive polyimide layer (i) that is in contact with the surface of the copper foil, and a low expansion polyindo layer (ii).

  The adhesive polyimide layer (i) is made of polyimide obtained by reacting a tetracarboxylic anhydride component and a diamine component, and at least pyromellitic dianhydride (PMDA) as a raw acid anhydride component, 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) is used as the diamine component of the raw material. PMDA contributes to improving the solder heat resistance of polyimide, and BAPP contributes to improving the adhesion of polyimide to the copper foil. From such a viewpoint, PMDA is contained in the raw acid anhydride component and BAPP is contained in the diamine component in an amount of 50 mol% or more, preferably 90 mol% or more, more preferably 90 to 100 mol%. Used in. Furthermore, by using both PMDA and BAPP at 50 mol% or more, particularly 90 mol or more, both high polyimide film strength (particularly tear strength) and high adhesive strength with copper foil can be achieved. As a result, polyimide insulation layer And the peel strength of the copper foil can be improved.

In addition, the adhesive polyimide layer (i) includes 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-oxydiphthalic dianhydride as raw acid anhydride components. It is preferable to use one or more tetracarboxylic anhydrides selected from the group consisting of (ODPA). BPDA and ODPA have the effect of lowering the glass transition temperature to such an extent that they do not affect the decrease in polyimide solder heat resistance. For example, sufficient adhesion can be ensured even in thermocompression bonding (lamination) with copper foil. . The glass transition temperature of polyimide is preferably in the range of 280 to 320 ° C. In addition, BPDA and ODPA contribute to lowering the film strength of polyimide, but lower the imide group concentration, thus improving the dielectric properties and further contributing to the reduction of polyimide polar groups, improving the moisture absorption properties of polyimide. , FPC transmission loss can be reduced. From such a viewpoint, it is preferable to use BPDA or ODPA in the range of 4 to 10 mol% as the acid anhydride component of the raw material of the adhesive polyimide layer (i). In this case, PMDA is preferably used in a range of 90 to 96 mol% with respect to the raw acid anhydride component. Here, the “imide group concentration” means a value obtained by dividing the molecular weight of the imide group (— (CO) ₂ —N—) in the polyimide by the molecular weight of the entire structure of the polyimide.

  The polyimide insulating layer preferably has a thermal linear expansion coefficient (CTE) in the range of 10 to 30 ppm / K in order to suppress warpage and dimensional stability degradation when the copper clad laminate is formed. The polyimide insulating layer has a plurality of polyimide layers, but the low expansion polyimide layer (ii) is preferably applied as a base film layer (main layer of the insulating resin layer). The CTE of the polyimide constituting the low expansion polyimide layer (ii) is in the range of 1 to 25 ppm / K, preferably in the range of 1 to 25 ppm / K, more preferably in the range of 10 to 20 ppm / K.

  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 transmission characteristics in a high frequency range when used for a circuit board such as a flexible circuit board (hereinafter sometimes referred to as “FPC”), the polyimide insulating layer has a formula (a );
_{E 1 = √ε 1 × Tanδ 1} ··· (a)
[Where ε ₁ indicates a dielectric constant at 10 GHz by the cavity resonator perturbation method, and Tan δ ₁ indicates a dielectric loss tangent at 10 GHz by the cavity resonator perturbation method]
The E ₁ value, which is an index indicating the dielectric characteristics at 10 GHz by the cavity resonator perturbation method calculated based on the above, is less than 0.009, preferably in the range of 0.0025 to 0.007, more preferably The range of 0.0025 to 0.006 is preferable. 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, the dielectric constant at 10 GHz (ε ₁₎ 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 3.3 or less, and the dielectric loss tangent (Tanδ ₁ ) is preferably less than 0.005. When the dielectric constant of the polyimide insulating layer at 10 GHz exceeds 3.3 and the dielectric loss tangent is 0.005 or more, an inconvenience of loss of electric signals is likely to occur when used on a circuit board such as an FPC.

  From the ease of control of the thickness and physical properties of the polyimide insulating layer, the adhesive polyimide layer (i) and the low-expansion polyimide layer (ii) are dried by heat treatment after applying the polyamic acid solution directly on the copper foil, It is preferably formed by a so-called casting (coating) method for curing. 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 the low expansion polyimide layer (ii) in the polyimide insulating layer is composed of an acid anhydride component including an aromatic tetracarboxylic acid anhydride and two terminal carboxylic acid groups of dimer acid. A dimer acid type diamine substituted with an amino group or a diamine component containing an aromatic diamine, and a polyimide obtained by reacting the dimer acid type diamine with respect to the total diamine component, Preferably it is in the range of 1 to 15 mol%, more preferably in the range of 4 to 15 mol%. When the dimer acid type diamine is less than 1 mol%, the dielectric properties of the polyimide tend to be lowered, and when it exceeds 15 mol%, the heat resistance tends to be deteriorated due to a decrease in the glass transition temperature of the polyimide.

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

[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).

[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 the polyimide for forming the low expansion polyimide layer (ii) can be understood by explaining the acid anhydride and the diamine. Is done. 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 provided. 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 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).

[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.

  In view of the dielectric properties of polyimide for forming the low expansion polyimide layer (ii), examples of the aromatic tetracarboxylic acid anhydride suitably used for the preparation of the polyimide precursor include 3, 3 ′, 4, 4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid A dianhydride (DSDA), pyromellitic dianhydride (PMDA), etc. can be mentioned. 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, based on the dielectric properties of polyimide for forming the low-expansion polyimide layer (ii), the aromatic diamine suitably used for preparing the polyimide precursor is, for example, 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, and the like. Among them, particularly preferable diamine components include 2,2′-divinyl-4,4′-diaminobiphenyl (VAB), 2,2′-dimethyl-4,4′-diaminobiphenyl (m-TB), and the like. be able to. 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 surface of the copper foil in contact with the adhesive polyimide layer (i) is roughened, the ten-point average roughness (Rz) is 1.0 μm or less, and the arithmetic average The roughness (Ra) is 0.2 μm or less. The material of the copper foil may be a copper alloy.

  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. Based on such knowledge, the present inventors have further investigated the reduction of the conductor loss. When the surface roughness of the copper foil is lowered to a certain extent, the effect of reducing the conductor loss may not be so great. all right. Further, when the surface roughness is lowered to satisfy the electrical performance requirement standard, the adhesive strength (peeling strength) between the copper foil and the polyimide insulating layer becomes weak. Therefore, it is possible to satisfy the electrical performance requirements, and from the viewpoint of ensuring adhesion with the polyimide insulating layer, the surface of the copper foil needs to be chromated.

In the copper-clad laminate of the present embodiment, the surface of the copper foil in contact with the adhesive polyimide layer (i) has been subjected to a metal deposition treatment for depositing zinc and chromium, and the zinc element present on the surface of the copper foil The amount (Zn) is in the range of 0.01 to 0.2 mg / dm ² , preferably 0.02 to 0.15 mg / dm ² , and the amount of chromium element (Cr) is 0.02 to 0. .2 mg / dm ² , preferably 0.02 to 0.15 mg / dm ² , and the total amount of zinc element and chromium element (Zn + Cr) is 0.03 to 0.3 mg / dm ² . It is controlled to be within the range. The zinc element suppresses oxidation of the copper foil, and the chromium element is effective in improving the peel strength with the polyimide insulating layer. However, these metal elements cause etching residues if the amount is too large. The zinc element and chromium element present on the surface of the foil are defined as the amount of adhesion within the above range.

  The precipitation process of the zinc element and the chromium element can be formed by sequentially performing, for example, a zinc plating process and a chromate process. Zinc plating and chromate treatment can be performed by a known method, and the amount of adhesion within the above range can be controlled in consideration of the competitive relationship between dissolution of the zinc plating layer and chromium element adhesion in the chromium element precipitation treatment. .

In the copper clad laminate of the present embodiment, the amount of nickel element (Ni) attached to the surface of the copper foil in contact with the adhesive polyimide layer (i) is 1.4 mg / dm ² or less, preferably 0.8 mg. / Dm ² or less, more preferably 0.1 mg / dm ² or less. Nickel element is an effective metal species for adhesion to the polyimide insulating layer and its long-term heat-reliability or chemical resistance, but if this amount is too large, it will cause etching residue, so 1.4 mg / dm ² or less.

Nickel is a solid solution with respect to copper and can create an alloy state, or nickel is easy to diffuse and form an alloy state with respect to copper. In such a state, the electric resistance is larger than that of copper alone, in other words, the conductivity is reduced. For this reason, if the amount of nickel element deposited on the copper foil surface is large, the resistance of copper alloyed with nickel increases. As a result, a loss during signal transmission due to an increase in resistance of the signal wiring due to the skin effect increases. From such a viewpoint, in the copper clad laminate of the present embodiment, the copper foil controls the amount of nickel element attached to the surface in contact with the adhesive polyimide layer (i) to 0.01 mg / dm ² or less. Is most preferred.

In addition, the present inventors have confirmed that the adhesion strength between the resin and the copper foil and its long-term reliability or chemical resistance decrease as the amount of the deposited metal deposited decreases. From such a viewpoint, in the copper-clad laminate of the present embodiment, cobalt and molybdenum, which are difficult to make an alloy state with copper and hardly increase resistance compared to nickel, are formed on the surface of the copper foil. The presence of a certain amount ensures the adhesive strength between the resin and the copper foil, its long-term reliability, and chemical resistance while suppressing conductor loss. Thus, the copper foil used in the present embodiment, the amount of cobalt element attached to the surface in contact with the adhesive polyimide layer (i) (Co) is in the range of 0.01 to 0.5 / dm ^2, the molybdenum element The amount (Mo) is in the range of 0.01 to 0.5 mg / dm ² . Moreover, the etching residue of the polyimide part between wiring at the time of wiring processing of a copper clad laminated board is suppressed by making the total amount (Co + Mo) of a cobalt element and a molybdenum element into the range of 0.1-0.7 mg / dm < ² >. In addition, it is possible to suppress a decrease in resistance to chemicals due to etching, and a decrease in the adhesive strength between the copper foil and the polyimide and its long-term reliability.

  The metal deposition treatment of the copper foil used for the copper clad laminate of the present embodiment is not particularly limited as long as it is a means capable of depositing the above-described metal in a predetermined amount on the surface of the copper foil. For example, as an example of the metal deposition treatment, a rust prevention treatment using the above metal can be exemplified, and specifically, the plating treatment is performed using a bath containing a predetermined amount of the above metal, and the surface of the copper foil is subjected to the above treatment. Examples thereof include a method for depositing a metal.

  Moreover, the copper foil used for the copper clad laminate of the present embodiment has, for example, siding, aluminum alcoholate, aluminum chelate, silane on the surface of the copper foil for the purpose of improving the adhesive strength in addition to the metal deposition treatment. Surface treatment with a coupling agent or the like may be performed.

  In the copper clad laminate of the present embodiment, a commercially available copper foil can be used as the copper foil. Specific examples thereof include CF-T49A-DS-HD (trade name) manufactured by Fukuda Metal Foil Powder Co., Ltd.

As described above, the increase in the resistance of the signal wiring due to the skin effect can be suppressed by reducing the surface roughness of the surface of the copper foil in contact with the polyimide insulating layer. 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 possible to satisfy the electrical performance requirements, and it is preferable to control the root mean square roughness (Rq) as a surface roughness parameter from the viewpoint of ensuring adhesion with the polyimide insulating layer. From the result of the simulation test shown in Japanese Patent Application No. 2013-205950, the present applicant found that the root mean square roughness (Rq) is greater than the current flowing on the copper foil surface due to the skin effect, as compared with other surface roughness indicators. Therefore, it is presumed that the influence of the fine irregularities on the surface of the copper foil is more accurately reflected. As an index of the surface roughness of the surface of the copper foil in contact with the polyimide insulating layer, the root mean square roughness (Rq ) And defining the root mean square roughness (Rq) within the above range, there is a trade-off relationship between ensuring adhesion to the polyimide insulating layer and suppressing increase in wiring resistance. We have found that we can be satisfied at the same time.

  In the copper clad laminate of the present embodiment, the copper foil has a root mean square roughness (Rq) of the surface in contact with the polyimide insulating layer, preferably in the range of 0.05 μm or more and less than 0.5 μm, more preferably The range of 0.1 μm or more and 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.

  Moreover, it is preferable that the surface of copper foil is roughened from a viewpoint of suppressing the adhesive force fall with the polyimide insulating layer accompanying the fall of the surface roughness of copper foil.

The roughening treatment of the copper foil can be formed, for example, by depositing a film (block film) having fine irregularities on the surface of the copper foil with the same material (for example, copper) as the copper foil by electroplating. In addition, although the roughening process of copper foil is confirmed by the scanning electron microscope (SEM) observation of the cross section of copper foil, the fine unevenness | corrugation of copper foil surface is with respect to the electric current which flows through the copper foil surface by a skin effect. It is presumed that it reflects the impact on the project more accurately. From such a viewpoint, the maximum value of the roughening height of the copper foil measured by SEM observation is preferably less than 0.6 μm. The maximum value of the roughening height of the copper foil is less than 0.6 μm, thereby simultaneously satisfying the requirements in a trade-off relationship between ensuring adhesion with the polyimide insulating layer and suppressing increase in wiring resistance. be able to.

  In the copper clad laminate of the present embodiment, for example, the preferred thickness of the copper foil when used for the production of FPC is in the range of 3 to 50 μm, more preferably in the range of 5 to 30 μm. In order to reduce the line width, the thickness of the copper foil is preferably in the range of 5 to 20 μm.

<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 which is a polyimide precursor for forming the adhesive polyimide layer (i) and the low expansion polyimide layer (ii).

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.

In the case where a plurality of polyimide insulating layers are used, other precursors can be sequentially formed 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. Two layers having a simple layer structure are preferable because they can be advantageously obtained industrially. The thickness of the precursor layer (after drying) is, for example, in the range of 6 to 100 μm, preferably in the range of 9 to 75 μm.

  When making a polyimide insulating layer into multiple layers, it is preferable to form a layer of a precursor so that adhesive polyimide layer (i) which touches copper foil may become a thermoplastic polyimide insulating 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 imidize a single layer or a plurality of precursor layers once to form a single layer or a plurality of polyimide insulating 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 copper foil, heat treatment in a low oxygen atmosphere is preferable. Specifically, it 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 insulating layer having an adhesive polyimide layer (i) and a low expansion polyimide layer (ii) 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 impedance matching 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.

[Viscosity measurement]
The viscosity of the resin was measured at 25 ° C. using an E-type viscometer (manufactured by Brookfield, trade name: DV-II + Pro). The number of revolutions was set so that the torque was 10% to 90%, and after 2 minutes from the start of measurement, the value when the viscosity was stabilized was read.

[Measurement of peel strength and long-term reliability]
The peel strength is composed of a base material (metal / resin layer) in which the metal on the conductor layer side is processed into a wiring having a width of 1 mm using a Tensilon tester (trade name: Strograph VE-1D, manufactured by Toyo Seiki Seisakusho Co., Ltd.). The resin layer side of the laminate was fixed to the SUS plate with a double-sided tape, and the force required to peel the metal wiring from the resin layer at a speed of 50 mm / min in the 180 ° direction was determined.
For long-term reliability, the retention rate was defined as the force at the time of peeling, which was obtained after heat-treating the above-mentioned wiring processed base material in an air atmosphere at 150 ° C. for 1000 hours, and the force before the heat treatment.
In the pass / fail judgment, a peel strength of 1.0 kN / m or higher is evaluated as “go”, and less than 1.0 kN / m is evaluated as “no”. For long-term reliability, a peel strength retention rate of 70% or higher is “excellent”. 60% or more was evaluated as “good”, 50% or more as “good”, and less than 50% as “impossible”.

[Evaluation of chemical resistance]
Evaluation of chemical resistance was performed at 50 ° C. for 1 hour in a hydrochloric acid aqueous solution adjusted to a concentration of 20 wt% on a base material (a laminate composed of a metal / resin layer) obtained by processing a metal on the conductor layer side into a wiring having a width of 1 mm. After immersion, the wiring was peeled off, the wiring and the resin layer side where the wiring was peeled off were observed, and the penetration width of the hydrochloric acid aqueous solution soaked between the metal / resin layers was evaluated.
The chemical resistance was evaluated as “excellent” when there was no soaking, “good” when the soaking width was less than 20 μm, “good” when the soaking width was less than 30 μm, and “impossible” when the soaking width was 30 μm or more.

[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 E8363C) and an SPDR resonator, and a resin sheet (cured resin sheet) at a predetermined frequency. The dielectric constant and dielectric loss tangent of were 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.

[Measurement of roughening height of copper foil]
The cross-section of the target copper foil is formed by ion irradiation using a cross-section sample preparation device (trade name: SM-09010 cross section polisher manufactured by JEOL Ltd.), and the exposed copper foil cross-section is observed by SEM at 5200 times to obtain a copper foil. A cross-sectional image was obtained. Using the obtained image, the roughening height was calculated based on the scale described in the image.

[Measurement of metal elements on the surface of copper foil subjected to metal deposition]
After the analysis surface of the copper foil is masked, the analysis surface is dissolved with 1N-nitric acid, and the volume is adjusted to 100 mL, and then measured using an inductively coupled plasma emission spectrometer (ICP-AES) Optima 4300 manufactured by PerkinElmer. did.

[Evaluation of transmission characteristics]
The transmission characteristics on the circuit processed side (transmission line side) were evaluated 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).
The evaluation of transmission loss is “good” when the frequency is 10 GHz and 2.2 dB / 10 cm or more and less than 2.4 dB / 10 cm, “good” when 2.4 dB / 10 cm or more and less than 2.7 dB / 10 cm, 2.7 dB / 10 cm The above was regarded as “impossible”. In addition, at a frequency of 40 GHz, “good” is 5.7 dB / 10 cm or more and less than 6.2 dB / 10 cm, “good” is 6.2 dB / 10 cm or more and less than 6.7 dB / 10 cm, and “impossible” is 6.7 dB / 10 cm or more. ".

The abbreviations used in the synthesis examples represent 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 TPE-R: 1,3-bis (4-aminophenoxy) benzene BAPP: 2,2-bis [4- (4-aminophenoxy) Phenyl] propane PMDA: pyromellitic dianhydride BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride DMAc: N, N-dimethylacetamide

(Synthesis Example 1)
To the reaction vessel, DMAc was added in an amount such that the solid content after polymerization was 12 wt%, and BAPP was added. After sufficient stirring until the charged diamine was completely dissolved, PMDA was added so that the molar ratio of acid anhydride: diamine was 0.990: 1.000. Thereafter, stirring was continued at room temperature for 3 hours to obtain a polyamic acid solution A having a viscosity of 2,300 cP.

(Synthesis Example 2)
To the reaction vessel, DMAc was added in an amount such that the solid content concentration after polymerization was 15 wt%, and m-TB and DDA were charged so that the molar ratio (m-TB: DDA) was 90:10. After sufficiently stirring until the charged diamine was completely dissolved, PMDA and BPDA were added so that the molar ratio of acid anhydride: diamine was 0.985: 1.000. PMDA and BPDA were added so that the molar ratio (PMDA: BPDA) was 80:20. Thereafter, stirring was continued at room temperature for 3 hours to obtain a polyamic acid solution B having a viscosity of 26,000 cP.

Example 1
Electrolytic copper foil (thickness: 12 μm, surface roughness Rz in the MD direction on the polyimide insulating layer side) Rz: 0.5 μm, Ra: 0.1 μm, Rq: 0.2 μm ) Was prepared. After roughening the surface of this copper foil, a plating process (a process of seeding with a metal stone) containing a predetermined amount of cobalt and molybdenum was performed, and further a galvanizing process and a chromate process were performed to obtain a copper foil 1. . Table 1 shows analytical values of the metal elements subjected to the metal precipitation treatment in the copper foil 1. Moreover, the SEM photograph in the cross section of the copper foil 1 is shown in FIG. Referring to the SEM photograph, the maximum value of the roughening height of the roughening treatment was 0.25 μm.

  The polyamic acid solution A, the polyamic acid solution B, and the polyamic acid solution A are sequentially applied (cast) to the surface of the copper foil 1 that has been subjected to the metal precipitation treatment, and the thicknesses after the heat treatment are 4 μm, 42 μm, and 4 μm, respectively. did. After drying, stepwise heat treatment was performed from 130 ° C. to finally 300 ° C. or more to complete imidization, and a single-sided copper-clad laminate 1 was obtained. The copper foil 1 is overlapped on the polyimide insulating layer side of the obtained single-sided copper-clad laminate 1 and thermocompression bonded (laminated) for 15 minutes under the conditions of 360 ° C. and pressure 6.7 MPam. Obtained. The evaluation results of the double-sided copper-clad laminate 1 are shown in Table 2. As shown in Table 2, the transmission loss at 10 GHz and 40 GHz of the double-sided copper-clad laminate 1 is 2.3 dB / 10 cm and 6.1 dB / 10 cm, respectively, and the film obtained by etching away the copper foil The dielectric properties are shown in Table 3.

(Example 2)
An electrolytic copper foil (thickness: 12 μm, surface roughness Rz in the MD direction on the polyimide insulating layer side: 0.8 μm, Ra: 0.2 μm, Rq: 0.2 μm) was prepared. After the surface of the copper foil is roughened, it is plated with a predetermined amount of nickel (metal deposition treatment), plated with a predetermined amount of cobalt and molybdenum, and further plated with zinc and chromate. Processing was performed sequentially to obtain a copper foil 2. Table 1 shows the analytical values of the metal elements subjected to the metal precipitation treatment in the copper foil 2. Moreover, when the SEM photograph in the cross section of the copper foil 2 was referred, the maximum value of the roughening height of a roughening process was 0.09 micrometer.

  A double-sided copper clad laminate 2 was obtained in the same manner as in Example 1 except that the copper foil 2 was used instead of the copper foil 1. The evaluation results of the double-sided copper-clad laminate 2 are shown in Table 2. As shown in Table 2, the transmission loss at 10 GHz and 40 GHz of the double-sided copper-clad laminate 2 was 2.2 dB / 10 cm and 5.8 dB / 10 cm, respectively. Table 3 shows the dielectric properties of films obtained by etching away copper foil in the same manner as in Example 1.

(Example 3)
An electrolytic copper foil (thickness: 12 μm, surface roughness Rz in the MD direction on the polyimide insulating layer side: 0.8 μm, Ra: 0.2 μm, Rq: 0.2 μm) was prepared. After the surface of this copper foil is roughened, it is plated with a predetermined amount of nickel (metal deposition treatment), then plated with a predetermined amount of cobalt and molybdenum, and further chromated. A copper foil 3 was obtained. Table 1 shows analytical values of the metal elements subjected to the metal precipitation treatment in the copper foil 3. Moreover, when the SEM photograph in the cross section of the copper foil 3 was referred, the maximum value of the roughening height of a roughening process was 0.09 micrometer.

  A double-sided copper clad laminate 3 was obtained in the same manner as in Example 1 except that the copper foil 3 was used instead of the copper foil 1. The evaluation results of the double-sided copper-clad laminate 3 are shown in Table 2. As shown in Table 2, the transmission loss at 10 GHz and 40 GHz of the double-sided copper-clad laminate 3 was 2.2 dB / 10 cm and 6.1 dB / 10 cm, respectively. Table 3 shows the dielectric properties of films obtained by etching away copper foil in the same manner as in Example 1.

(Comparative Example 1)
An electrolytic copper foil (thickness: 12 μm, surface roughness Rz in the MD direction on the polyimide insulating layer side: 1.0 μm, Ra: 0.2 μm, Rq: 0.1 μm) was prepared. After roughening the surface of the copper foil, a plating process (metal deposition process) containing a predetermined amount of nickel was performed, and further a galvanizing process and a chromate process were performed to obtain a copper foil 4. Table 1 shows the analytical values of the metal elements subjected to the metal precipitation treatment in the copper foil 4. Moreover, when the SEM photograph in the cross section of the copper foil 4 was referred, the maximum value of the roughening height of a roughening process was 0.25 micrometer.

  A double-sided copper clad laminate 4 was obtained in the same manner as in Example 1 except that the copper foil 4 was used instead of the copper foil 1. The evaluation results of the double-sided copper clad laminate 4 are shown in Table 2. As shown in Table 2, the transmission loss at 10 GHz and 40 GHz of the double-sided copper-clad laminate 4 was 2.5 dB / 10 cm and 6.8 dB / 10 cm, respectively. Table 3 shows the dielectric properties of films obtained by etching away copper foil in the same manner as in Example 1.

(Comparative Example 2)
A double-sided copper-clad laminate 5 was obtained in the same manner as in Example 1 except that a commercially available polyimide film (trade name; PIXEO, manufactured by Kaneka Corporation) was used. The evaluation results of the double-sided copper-clad laminate 5 are shown in Table 2. As shown in Table 2, the transmission loss of the double-sided copper-clad laminate 5 at 10 GHz and 40 GHz was 2.8 dB / 10 cm and 8.8 dB / 10 cm, respectively. Table 3 shows the dielectric properties of films obtained by etching away copper foil in the same manner as in Example 1.

  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 (5)

A copper clad laminate comprising a polyimide insulating layer and a copper foil laminated on at least one surface of the polyimide insulating layer,
The polyimide insulating layer has the following constitutions Ia to Ic:
Ia) having an adhesive polyimide layer (i) in contact with the surface of the copper foil and a low expansion polyimide layer (ii) laminated directly or indirectly on the adhesive polyimide layer (i);
Ib) The adhesive polyimide layer (i) comprises a polyimide obtained by reacting a tetracarboxylic acid anhydride component and a diamine component, and pyromellitic dianhydride (PMDA) is added to the acid anhydride component. Containing 50 mol% or more, and containing 50 mol% or more of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) with respect to the diamine component;
Ic) The following mathematical formula (a),
_{E 1 = √ε 1 × Tanδ 1} ··· (a)
[Where ε ₁ indicates a dielectric constant at 10 GHz by the cavity resonator perturbation method, and Tan δ ₁ indicates a dielectric loss tangent at 10 GHz by the cavity resonator perturbation method]
The E ₁ value, which is an index indicating dielectric properties, calculated based on the above is less than 0.009;
With
Further, the copper foil has the following configurations IId and IIe:
IId) The surface in contact with the adhesive polyimide layer (i) is roughened, the ten-point average roughness (Rz) of the copper foil surface is 1.0 μm or less, and the arithmetic average height (Ra) is 0. 2 μm or less;
IIe) The amount of nickel element (Ni) adhering to the surface in contact with the adhesive polyimide layer (i) is 1.4 mg / dm ² or less, and the amount of zinc element (Zn) is 0.01-0.2 mg / Within the range of dm ² , the amount of chromium element (Cr) is within the range of 0.02 to 0.2 mg / dm ² , and the total amount of zinc element and chromium element (Zn + Cr) is 0.03 to 0.3 mg / within the range of dm ² ;
And a copper-clad laminate having a mean square roughness (Rq) of a surface in contact with the polyimide insulating layer in the copper foil in a range of 0.05 μm or more and less than 0.5 μm . The surface of the copper foil in contact with the adhesive polyimide layer (i) is roughened, and the maximum roughening height of the roughening treatment measured by scanning electron microscope (SEM) observation of the copper foil cross section but copper-clad laminate according to claim 1 is less than 0.6 .mu.m. The amount (Ni) of nickel element adhering to the surface of the copper foil in contact with the adhesive polyimide layer (i) is 0.01 mg / dm ² or less, and the amount of cobalt element (Co) is 0.01-0. in the range of 5 mg / dm ^2, the amount of elemental molybdenum (Mo) is in the range of 0.01 to 0.5 / dm ^2, and the total amount of cobalt element and elemental molybdenum (Co + Mo) is 0.1 to 0. copper-clad laminate according to claim 1 or 2 in the range of 7 mg / dm ^2. The printed wiring board formed by carrying out wiring circuit processing of the copper foil of the copper clad laminated board of any one of Claims 1-3 . The usage method of the printed wiring board which uses the printed wiring board of Claim 4 in the frequency area | region within the range of 1 GHz-40 GHz.