KR102288004B1 - Flexible copper-clad laminate and flexible circuit substrate - Google Patents

Abstract

(Problem) Flexible copper clad laminate and flexible having a copper foil layer suitable for forming high-density wiring, withstanding intermittent and repeated sliding, and having excellent bending resistance that can prevent disconnection or cracking of wiring circuits even in a narrow case A circuit board is provided.
(Solution) A flexible copper clad laminate is provided with a polyimide insulating layer (A), a first copper foil layer (B1), and a second copper foil layer (B2), and the first copper foil layer (B1) has a thickness ( T1) is in the range of 5 to 20 µm, and in the relationship between this thickness (T1) and the average grain size (D1) in the cross section in the thickness direction, (T1) × (D1) ≤ 100 µm The second copper foil layer (B2) has a thickness in a range of 5 to 20 µm, a tensile modulus in a range of 10 to 25 GPa, and an average crystal grain size in a cross section in the thickness direction of 40 to 70 The ratio (I/Io) of the diffraction intensity (I) of the (200) plane determined by X-ray diffraction and the diffraction intensity (Io) of the (220) plane determined by X-ray diffraction of fine powder copper within the range of μm (I/Io) is It consists of copper foil in the range of 12-30.

Description

Flexible copper clad laminate and flexible circuit board

This invention relates to the flexible copper clad laminated board used for a flexible circuit board (FPC), and the flexible circuit board which used the said flexible copper clad laminated board as a material.

In recent years, electronic devices represented by mobile phones, notebook computers, digital cameras, game machines, etc. have been rapidly reduced in size, thickness, and weight, and materials used for these devices have a high density that can accommodate parts even in a small space. A high-performance material has come to be desired. Also in a flexible circuit board, since high-density of component storage has progressed with the spread of high-performance small electronic devices, such as a smart phone, it is necessary to accommodate a flexible circuit board in the case narrower than before. Therefore, also in the flexible copper clad laminated board which is a material of a flexible circuit board, the improvement of the bending resistance from a material surface is calculated|required. Hereinafter, in this specification, bending so that the upper surface side of FPC may be inverted by 180 degreeC and may become a lower surface side may be called "folding".

By controlling the elastic modulus of the polyimide base film and cover film used for a flexible copper clad laminated board, in patent document 1 as what is intended application to such a use, by reducing the stiffness of the flexible circuit board total, bending resistance A technique to improve it has been proposed. However, control of the properties of polyimide or cover film alone is insufficient for a strict bending mode of folding and storing in an electronic device, and a flexible copper clad laminate that can be used for a flexible circuit board excellent in sufficient bending resistance cannot be provided.

Moreover, in patent document 2, the copper foil for heat processing which paid attention to the crystal grain size of copper foil as an approach from the copper foil side from a viewpoint of densification with respect to the inside of an electronic device, and suppressed springback resistance is proposed. This proposal is a technique for using a rolled copper foil containing various appropriate additives in the copper foil, applying a sufficient amount of heat to enlarge the crystal grains, thereby increasing the crystal grain size, and as a result, improving the springback resistance of the copper foil. .

However, with respect to a small electronic device represented by a smart phone, additional high density is requested, and it is difficult to meet the request with the above-mentioned prior art alone.

As a means of obtaining a flexible circuit board for high-density wiring, it is generally known that the thickness reduction of the metal layer of a flexible metal-clad laminate used as a material is effective, and a technique of forming a thin metal layer on a polyimide film by sputtering or electrolytic plating It is proposed (for example, refer patent document 3). However, only the approach of thinning the metal layer is limited due to reasons such as limiting the design.

Japanese Patent Laid-Open No. 2007-208087 Japanese Laid-Open Patent Publication No. 2010-280191 Japanese Laid-Open Patent Publication No. 11-268183

The present invention has been made in view of the above problems, and the object thereof is not only to have a copper foil layer suitable for forming high-density wiring, but also to withstand intermittent and repeated sliding, and also to break or crack the wiring circuit even in a narrow case. To provide a flexible copper clad laminate having excellent bending resistance, and a flexible circuit board that can prevent

As a result of earnest examination by the present inventors in order to solve the said subject, by paying attention to the characteristic of elastoplastic deformation in the folding process of the flexible copper clad laminated board in which copper foil and polyimide film were laminated|stacked, flexible copper coating which can solve the said subject The present invention has been completed by finding out that a laminate can be provided.

The flexible copper clad laminate of the present invention comprises a polyimide insulating layer (A), a first copper foil layer (B1) formed on one surface of the polyimide insulating layer (A), and the polyimide insulating layer (A). It is provided with the 2nd copper foil layer B2 formed in the other surface. The flexible copper clad laminate of the present invention is composed of the following a and b:

a) The first copper foil layer (B1) has a thickness (T1) in the range of 5 to 20 µm, and in the relationship between the thickness (T1) and the average grain size (D1) in the cross section in the thickness direction, (T1) × (D1) ≤ 100 µm 2 composed of a copper foil;

b) The thickness of the second copper foil layer (B2) is in the range of 5 to 20 µm, the tensile modulus is in the range of 10 to 25 GPa, and the average grain size in the cross section in the thickness direction is 40 to 70 µm. The ratio (I/Io) of the diffraction intensity (I) of the (200) plane determined by X-ray diffraction to the diffraction intensity (Io) of the (220) plane determined by X-ray diffraction of fine powder copper is 12 to What consists of copper foil in the range of 30;

to provide

The flexible copper clad laminated board of this invention is further the structure of c;

c) Thickness exists in the range of 7-17 micrometers, and the said polyimide insulating layer (A) exists in the range whose tensile elasticity modulus in 25 degreeC is 2-9 GPa;

may be provided.

The flexible copper clad laminated board of this invention is further the structure of d;

d) the ratio of the thickness of the polyimide insulating layer (A) and the second copper foil layer (B2) [thickness of the second copper foil layer (B2)/thickness of the polyimide insulating layer (A)] is in the range of 0.48 to 2.4 what is mine;

may be provided.

The flexible circuit board of this invention uses the 2nd copper foil layer (B2) of the flexible copper clad laminated board in any one of the above, and uses at least one part of a wiring circuit for a bending part.

As for the flexible circuit board of this invention, the 1st copper foil layer (B1) of the position corresponded to a bending part at least may be removed.

Since the flexible copper clad laminated board of this invention can express the high bending resistance calculated|required for a wiring board, it can provide the material for flexible circuit boards excellent in the connection reliability in the state bent in an electronic device. Therefore, the flexible copper clad laminated board of this invention is used especially suitably for electronic components, such as a bending part around small liquid crystals, such as a smart phone, which bending resistance is calculated|required. Moreover, since the flexible copper clad laminated board of this invention has the performance which can withstand the intermittent repeated sliding required for a wiring board, and a copper foil layer advantageous for forming high-density wiring, the lead-light cable in a hard disk drive It is also preferably used as a material for a flexible circuit board for a dragon.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional explanatory drawing (part) of the flexible circuit board obtained by partially removing the 1st copper foil layer of a flexible copper clad laminated board.
It is a planar explanatory drawing which shows the state of the copper wiring of the test circuit board piece used in the Example.
It is a side explanatory drawing which shows the state of the sample stage and test circuit board piece in a bending test (state diagram which fixed the test circuit board piece on the sample stage).
It is a side explanatory drawing which shows the state of the sample stage in a bending test, and a test circuit board piece (state diagram before pressing the bending point of a test circuit board piece with a roller).
It is a side explanatory drawing which shows the state of the sample stage in a bending test, and a test circuit board piece (state diagram which pressed the bending point of a test circuit board piece with a roller).
Fig. 6 is a side explanatory view showing the state of a sample stage and a test circuit board piece in a bending test (a state diagram in which a bending point is opened and the test piece is returned to a flat state);
Fig. 7 is a side explanatory view showing the state of a sample stage and a test circuit board piece in a bending test (a state diagram in which a fold portion at a bending point is pressed with a roller to even out).

form for carrying out the invention

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

<Flexible Copper Clad Laminate>

The flexible copper clad laminate of this embodiment is a polyimide insulating layer (A), the 1st copper foil layer (B1) formed in one surface of this polyimide insulating layer (A), This polyimide insulating layer (A) and a second copper foil layer (B2) formed on the other surface of the . This flexible copper clad laminated board etches a 1st copper foil layer (B1) and a 2nd copper foil layer (B2), a wiring circuit process is carried out, copper wiring is formed, and it is used as a flexible circuit board. In this case, it is advantageous to form the first copper foil layer (B1) as a copper wiring of high-density wiring, and to form the second copper foil layer (B2) as a copper wiring corresponding to the bent portion.

<Copper foil>

The flexible copper clad laminate of this embodiment WHEREIN: The thickness T1 of the 1st copper foil layer (B1) exists in the range of 5-20 micrometers, Preferably the inside of the range of 6-19 micrometers is good. When the thickness (T1) of the first copper foil layer (B1) is less than 5 μm, for example, in the production of a flexible copper clad laminate, a polyimide insulating layer (A) is formed on the first copper foil layer (B1) A process WHEREIN: The rigidity of 1st copper foil layer (B1) itself falls, As a result, the problem which wrinkles etc. generate|occur|produce on a flexible copper clad laminated board arises. Further, when the thickness T1 of the first copper foil layer B1 exceeds 20 µm, the amount of sagging of the copper wiring formed by etching with the etching solution increases, so that insulation failure between adjacent wirings occurs, and the wiring circuit It becomes a tendency for refinement|miniaturization to become difficult.

Further, in the relationship between the thickness (T1) of the first copper foil layer (B1) and the average grain size (D1) in the cross section in the thickness direction, (T1) × (D1) is 100 µm 2 or less, preferably It is good to set it as 80 micrometers or less, More preferably, it is 70 micrometers or less. By setting it as such a range, it becomes possible to refine|miniaturize the copper wiring formed by etching with an etching liquid, for example. Further, the lower limit of (T1) × (D1) is not particularly limited, but by making (T1) × (D1) smaller, the etching rate in the copper foil thickness direction at the time of formation of the copper wiring with the etching solution increases, From the viewpoint of easily causing undercutting in the copper wiring, it is preferably 5 µm 2 or more, and more preferably 10 µm 2 or more. In addition, the average grain size in the cross section of the thickness direction of the copper foil layer prescribed|regulated by this invention can be calculated|required with the measuring method described in a later Example.

The flexible copper clad laminate of this embodiment WHEREIN: The surface of the 1st copper foil layer (B1) may be roughened, Preferably the 1st copper foil layer (B1) in contact with the polyimide insulating layer (A) ), the surface roughness (Rz) of the surface is preferably in the range of 0.7 to 2.5 µm, preferably in the range of 0.7 to 2.2 µm, more preferably in the range of 0.8 to 1.6 µm. If the value of the surface roughness (Rz) does not fall below the above lower limit, it becomes difficult to guarantee adhesion reliability with the polyimide insulating layer (A). It is inhibited, and it becomes easy to produce trouble in formation of a fine wiring circuit. In addition, surface roughness Rz is a value measured according to the prescription|regulation of JIS B0601.

The flexible copper clad laminate of this embodiment WHEREIN: The thickness of the 2nd copper foil layer (B2) exists in the range of 5-20 micrometers, Preferably the inside of the range of 8-19 micrometers is good. When the thickness of the second copper foil layer (B2) is less than 5 µm, for example, in the production of the flexible copper clad laminate, in the step of forming the polyimide insulating layer (A) on the second copper foil layer (B2) The rigidity of 2nd copper foil layer (B2) itself falls, As a result, the problem which wrinkles etc. generate|occur|produce on a flexible copper clad laminated board arises. Moreover, when it exceeds 20 micrometers, bending resistance will fall because the bending stress applied to the copper foil layer (or copper wiring) at the time of bending a flexible copper clad laminated board (or FPC) becomes large.

Moreover, the tensile modulus of elasticity of a 2nd copper foil layer (B2) exists in the range of 10-25 GPa, Preferably the inside of the range of 10-20 GPa is good. When the tensile modulus of elasticity of the second copper foil layer (B2) is less than 10 GPa, for example, in the process of forming a polyimide insulating layer (A) on the second copper foil layer (B2) in the production of a flexible copper clad laminate In this, the rigidity of 2nd copper foil layer (B2) itself falls, As a result, the problem which wrinkles etc. generate|occur|produce on a flexible copper clad laminated board arises. In addition, when the tensile modulus of elasticity of the second copper foil layer (B2) exceeds 25 GPa, the bending stress applied to the copper foil layer (or copper wiring) when the flexible copper clad laminate (or FPC) is bent increases, so that the bending resistance is improved will be degraded

The flexible copper clad laminate of this embodiment WHEREIN: The average crystal grain diameter in the cross section of the thickness direction of a 2nd copper foil layer (B2) exists in the range of 40-70 micrometers. By setting it as such a range, extension of the crack of the copper foil layer (or copper wiring) which generate|occur|produces when bending a flexible copper clad laminated board (or FPC) can be suppressed, and bending resistance can be improved as a result.

In addition, the second copper foil layer (B2) has a (200) plane diffraction intensity (I) determined by X-ray diffraction in the thickness direction, and a (220) plane diffraction intensity (220) plane determined by X-ray diffraction of fine powder copper ( The ratio (I/Io) of Io) is in the range of 12 to 30. By setting it as such a range, the bending resistance of a flexible copper clad laminated board (or FPC) can be improved. Here, the I value and the Io value can be measured by X-ray diffraction method, and X-ray diffraction in the thickness direction of the copper foil layer means the surface of the copper foil layer (rolled surface when the copper foil layer is made of rolled copper foil). It confirms the orientation, and the diffraction intensity (I) of the (200) plane represents the intensity integral value of the (200) plane calculated|required by X-ray diffraction. In addition, the diffraction intensity (Io) shows the intensity integral value of the (220) plane of fine-powdered copper (The Kanto Chemical Co., Ltd. copper powder reagent grade 1, 325 mesh, purity 99.99% or more).

The flexible copper clad laminate of this embodiment WHEREIN: The surface of the 2nd copper foil layer (B2) may be roughened, and when the relationship with the rigidity of the 2nd copper foil layer (B2) is considered, Preferably polyimide insulation It is good that the surface roughness (10-point average roughness: Rz) of the surface of the 2nd copper foil layer (B2) in contact with a layer (A) exists in the range of 0.1-1.5 micrometers. If the value of the surface roughness (Rz) does not fall below the lower limit, it becomes difficult to guarantee adhesion reliability with the polyimide insulating layer (A). At the time, the unevenness|corrugation of the roughened surface becomes a starting point of crack generation|occurrence|production easily, As a result, the bending resistance of a flexible copper clad laminated board (or FPC) is reduced. In addition, surface roughness Rz is a value measured according to the prescription|regulation of JIS B0601.

<Polyimide Insulation Layer>

In the flexible copper clad laminate of this embodiment, although the thickness of a polyimide insulating layer (A) can be set to the thickness within a predetermined range according to the thickness, rigidity, etc. of a 2nd copper foil layer (B), for example, 7- It is preferable to exist in the range of 17 micrometers, and it is more preferable to exist in the range of 8-13 micrometers. When the thickness of a polyimide insulating layer (A) is less than the said lower limit, it will become a tendency which the problem, such as a thing which cannot guarantee electrical insulation and handling becomes difficult in a manufacturing process by the fall of handling property, will arise. On the other hand, when the thickness of the polyimide insulating layer (A) exceeds the above upper limit, the bending stress applied to the copper foil layer (or copper wiring) when the flexible copper clad laminate (or FPC) is bent becomes larger, and the It becomes a tendency to reduce bending resistance remarkably.

Moreover, the tensile elastic modulus in 23 degreeC of a polyimide insulating layer (A) becomes like this. Preferably it exists in the range of 2-9 GPa, More preferably, it is good to exist in the range of 4-9 GPa. If the tensile modulus of elasticity of the polyimide insulating layer (A) is less than 2 GPa, the rigidity of the polyimide itself decreases, so that when processing a flexible copper-clad laminate into a circuit board, a handling problem such as generation of wrinkles occurs. there is. Conversely, when the tensile modulus of elasticity of the polyimide insulating layer (A) exceeds 9 GPa, the rigidity with respect to bending of the flexible copper clad laminate (or FPC) increases as a result, and when the flexible copper clad laminate (or FPC) is bent, copper The bending stress applied to the wiring increases, and the bending resistance decreases.

<Ratio of thickness of polyimide insulating layer (A) and second copper foil layer (B2)>

Further, in the present embodiment, as the configuration d, the ratio of the thickness of the polyimide insulating layer (A) and the second copper foil layer (B2) [thickness of the second copper foil layer (B2) / polyimide insulating layer (A) ) is preferably in the range of 0.48 to 2.4. When the thickness ratio is less than 0.48 or larger than 2.4, the maximum tensile strain when the portion plastically deformed at the time of bending is stretched increases, so that the bending resistance is lowered.

<The sum of the thicknesses of the polyimide insulating layer (A) and the second copper foil layer (B2)>

The flexible copper clad laminate of the present embodiment has a thickness [that is, the total thickness of the polyimide insulating layer (A) and the second copper foil layer (B2)] in the range of 12 to 37 µm, preferably 16 to 32 It is good in the range of μm. When the thickness of the flexible copper-clad laminate is less than 12 µm, the rigidity of the flexible printed wiring board formed by processing the copper foil of the flexible copper-clad laminate as a wiring circuit decreases, and it tends to easily cause elastoplastic deformation due to bending. On the other hand, when the thickness of a flexible copper clad laminated board exceeds 37 micrometers, when FPC is bent, a larger bending stress will be applied to copper wiring, and the bending resistance will fall remarkably.

<Manufacture of flexible copper clad laminated board>

In the flexible copper clad laminate of the present embodiment, the first copper foil layer (B1), the polyimide insulating layer (A) and the second copper foil layer (B2) are laminated in this order, but advantageously the first copper foil layer (B1) ) is preferably formed as a copper wiring of high-density wiring, and the second copper foil layer (B2) is formed as a copper wiring corresponding to a bent portion. From such a viewpoint, the flexible copper clad laminated board of this embodiment is a polyimide precursor resin solution (also called polyamic acid solution) on the surface of the copper foil used as a 1st copper foil layer (B1) (it is hereafter called 1st copper foil). ) is coated, followed by drying and curing to prepare a single-sided copper-clad laminate, and then on the surface of the single-sided copper-clad laminate on the polyimide insulating layer (A) side copper foil ( Hereinafter, the method of thermocompression bonding of 2nd copper foil) is preferable. The polyimide insulating layer obtained by a method of directly coating a polyamic acid solution on the first copper foil serving as circuit wiring, a so-called casting method, can suppress the difference in the coefficient of linear thermal expansion in the longitudinal direction and the transverse direction, and has dimensional stability. can be improved, it is advantageous for forming a high-density wiring by processing the wiring circuit of the first copper foil layer (B1). The heat treatment conditions of the polyamic acid in the formation of the polyimide insulating layer (A) are, for example, after drying by heating the coated polyamic acid solution stepwise within a temperature range of less than 160°C, it is further 300 There is a method of curing by raising the temperature stepwise to ~400°C.

The polyimide insulating layer (A) may be formed only as a single layer, but considering the adhesiveness of the polyimide insulating layer (A) and the first copper foil layer (B1) and the second copper foil layer (B2), it is formed into multiple layers. It is desirable to do When making a polyimide insulating layer (A) into multiple layers, it can apply|coat and form another polyamic-acid solution sequentially on the polyamic-acid solution which consists of different structural components. When a polyimide insulating layer (A) consists of multiple layers, you may use polyimide precursor resin of the same structure 2 times or more.

A polyimide insulating layer (A) is demonstrated in detail. As above-mentioned, although it is preferable to make a polyimide insulating layer (A) into multiple layers, as the specific example, it is a polyimide insulating layer (A) with a low thermal expansion coefficient of ^{less than 30 x 10 -6} /K of thermal expansion. It is preferable to set it as the laminated structure containing a polyimide layer (i) and a ^{high thermal expansibility polyimide layer (ii) of 30 x 10 -6 /K or more of thermal expansion coefficients.} More preferably, the polyimide insulating layer (A) has at least one of the low thermal expansion polyimide layers (i), and preferably has a high thermal expansion polyimide layer (ii) on both sides thereof. It is preferable to make the polyimide layer (ii) in direct contact with the copper foil. Here, the "polyimide layer (i) of low thermal expansion property" refers to a thermal expansion coefficient of ^{less than 30 × 10 -6} /K, preferably within the range of 1 × 10 ^-6 to 25 × 10 ^-6 /K, particularly preferably The polyimide layer within the range of 3 × 10 ^-6 to 20 × 10 ^{-6 /K is said.} Moreover, "high thermal expansibility polyimide layer (ii)" means a polyimide layer having a coefficient of thermal expansion of 30 × 10 ^-6 /K or more, preferably within the range of 30 × 10 ^-6 to 80 × 10 ^-6 /K. , particularly preferably a polyimide layer within the range of ^{30 × 10 -6} to 70 × 10 ^{-6 /K.} Such a polyimide layer can be set as the polyimide layer which has a desired coefficient of thermal expansion by changing suitably the combination of the raw material to be used, thickness, and drying/hardening conditions.

The polyamic acid solution which provides the said polyimide insulating layer (A) can superpose|polymerize well-known diamine and an acid anhydride in presence of a solvent, and can manufacture it. At this time, it is preferable that the resin viscosity to be polymerized is, for example, in the range of 500 cps or more and 35,000 cps or less.

Examples of the diamine used as a raw material for polyimide include 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 4, 4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 2,4-toluenediamine, m-phenyl Rendiamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodi Phenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-dia Minodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenyl ether , 3,3-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy) ) Benzene, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4'-diamino-p -terphenyl, 3,3'-diamino-p-terphenyl, 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, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 2 , 2'-dimethyl-4,4'-diaminobiphenyl, 3,7-diaminodibenzofuran, 1,5-diaminofluorene, dibenzo-p-dioxine-2,7-diamine, 4 ,4'-diaminobenzyl etc. are mentioned.

Moreover, as an acid anhydride used as a raw material of a polyimide, For example, pyromellitic dianhydride, 3,3',4,4'- benzophenone tetracarboxylic dianhydride, 2,2',3, 3'-benzophenone tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene- 1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, 4 , 8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5, 6,7-hexahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloro Naphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5, 8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'- Biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3",4,4"-p-terphenyltetracarboxylic dianhydride, 2 ,2",3,3"-p-terphenyltetracarboxylic dianhydride, 2,3,3",4"-p-terphenyltetracarboxylic dianhydride, 2,2-bis(2,3 -dicarboxyphenyl)-propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, bis(2,3-di Carboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)sulfone dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1 ,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, perylene-2,3,8,9-tetracarboxylic acid Dianhydride, Perylene-3,4,9,10-Tetracar acid dianhydride, perylene-4,5,10,11-tetracarboxylic dianhydride, perylene-5,6,11,12-tetracarboxylic dianhydride, phenanthrene-1,2,7, 8-tetracarboxylic dianhydride, phenanthrene-1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, cyclopentane-1, 2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thi Offene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, etc. are mentioned.

As for the said diamine and an acid anhydride, only 1 type may be used respectively, and 2 or more types may be used together. Moreover, dimethylacetamide, N-methylpyrrolidinone, 2-butanone, diglyme, xylene etc. are mentioned as for the solvent used for superposition|polymerization, It can also use 1 type or in combination of 2 or more types.

In the present embodiment ^{, in order to obtain the low thermal expansion polyimide layer (i) with a thermal expansion coefficient of less than 30 x 10 -6} /K, pyromellitic dianhydride, 3,3',4,4' as an acid anhydride component of the raw material -Biphenyltetracarboxylic dianhydride, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2-methoxy-4,4'-diaminobenzanilide as the diamine component is used. Preferably, pyromellitic dianhydride and 2,2'-dimethyl-4,4'-diaminobiphenyl are the main components of each component of the raw material.

Moreover, in order to make ^{a polyimide layer (ii) of high thermal expansion property of thermal expansion coefficient 30 x 10 -6} /K or more, pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic as an acid anhydride component of a raw material Acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2 as a diamine component It is preferable to use ,2'-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenyl ether, and 1,3-bis(4-aminophenoxy)benzene, especially Preferably, pyromellitic dianhydride and 2,2'-bis[4-(4-aminophenoxy)phenyl]propane are the main components of each component of the raw material. Moreover, the preferable glass transition temperature of the polyimide layer (ii) of high thermal expansibility obtained in this way is 260 degreeC or more, and it is preferable to exist in the range of 280-320 degreeC. By setting the glass transition temperature to such a range, the adhesive strength and dimensional stability between the copper foil layer and the polyimide insulating layer (A) required when processing a flexible copper clad laminate by FPC, and solder required for solder bonding during component mounting It becomes a thing excellent in heat resistance.

Moreover, when the polyimide insulating layer (A) is made into a laminated structure of the polyimide layer (i) of low thermal expansion property and the polyimide layer (ii) of high thermal expansion property, Preferably, the polyimide layer (i) of low thermal expansion property and high heat It is good that the thickness ratio (low thermally expansible polyimide layer (i)/high thermally expansible polyimide layer (ii)) of expansible polyimide layer (ii) exists in the range of 2-12. When the value of this ratio is less than 2, since the polyimide layer (i) of low thermal expansion property with respect to the whole polyimide insulating layer (A) becomes thin, control of the dimensional characteristics of a polyimide film becomes difficult, and copper foil is etched. Since the dimensional change rate at the time of doing it becomes large, and since the polyimide layer (ii) of high thermal expansibility becomes thin when it exceeds 12, the adhesive reliability of a polyimide insulating layer (A) and copper foil will fall.

It is preferable that the 1st copper foil used for manufacture of the flexible copper clad laminated board of this embodiment uses electrolytic copper foil. Compared with rolled copper foil, an electrolytic copper foil is advantageous because it is easy to suppress the fall of the rigidity in the process of forming a polyimide layer on copper foil at the time of manufacture of a flexible copper clad laminated board, for example.

Moreover, the 1st copper foil used for manufacture of the flexible copper-clad laminated board of this embodiment is the influence of the thermal history (for example, heating for 10-60 minutes at 300-400 degreeC) at the time of manufacture of a flexible copper-clad laminated board. After receiving, the average crystal grain size (D1) is preferably in the range of 1 to 10 µm, more preferably in the range of 1 to 5 µm, it is good to use an electrolytic copper foil. A commercial item can be used as such an electrolytic copper foil, As the specific example, WS foil by Furukawa Denko Co., Ltd., HL foil by Nippon Electrolysis Co., Ltd., HTE foil by Mitsui Metals Mining Co., Ltd., etc. are mentioned. Moreover, even when other things are used including these commercial items, the 1st copper foil layer (B1) in the flexible copper clad laminated board of this embodiment may become in a predetermined range, so that, for example, a polyimide insulating layer ( After formation of A), it is also possible to perform thickness reduction of a copper foil layer by chemical polishing, such as an etching. In this case, it is preferable that the surface roughness (Rz) of the 1st copper foil layer (B1) after etching (the side which does not come into contact with a polyimide insulating layer (A)) of surface roughness (Rz) becomes 1.7 micrometers or less. By setting it as such a value of surface roughness, when processing the wiring circuit of the 1st copper foil layer (B1) and forming copper wiring, the dispersion|variation in the wiring space|interval can be suppressed.

It is preferable that the 2nd copper foil used for manufacture of the flexible copper clad laminated board of this embodiment uses rolled copper foil. As the rolled copper foil, copper alloy foil in which Ag or Sn is added as an additive element so that the (200) plane crystal orientation proceeds at the time of annealing in the step of forming a polyimide layer on the copper foil, the thermocompression bonding step, and the subsequent step, etc. can be heard As a well-known thing, HA foil by the JX Nikko Nisseki Metals Co., Ltd. product, and the HPF foil by SH Copper Products Co., Ltd. are mentioned.

Next, the thermocompression bonding conditions of the 2nd copper foil and single-sided copper clad laminated board in embodiment of this invention are demonstrated. The lamination temperature (t ₁ ), that is, the temperature of the hot press roll in the thermocompression bonding step, is the polyimide of the polyimide layer (ii) having high thermal expansion properties from the viewpoint of the adhesiveness of the adhesive layer with the second copper foil to the polyimide. It is necessary to set it as the glass transition temperature of mid or more, Preferably it is good to exist in the range of 300-400 degreeC. Moreover, it is preferable to thermocompression-bonding under the conditions of 50-500 Kg/cm and roll passing time of the linear pressure between heating rolls for 2 to 5 second. Although atmospheric atmosphere and an inert atmosphere are mentioned as atmosphere of a lamination, It is preferable that it is an inert atmosphere from a viewpoint of copper foil oxidation discoloration prevention. Here, the inert atmosphere has the same meaning as an inert atmosphere, and refers to a state substantially free of oxygen by being substituted with an inert gas such as nitrogen or argon.

Here, the crystal orientation of the (200) plane by the heat processing of 2nd copper foil is demonstrated in detail. In general, the above-described copper foil is softened by heat treatment, and the elastic modulus is lowered to become soft, and the preferential orientation of the (200) plane proceeds to develop a cubic structure. The crystal orientation of (200) plane proceeds by treatment for a predetermined time at a temperature equal to or higher than the semi-softening temperature, but at least 10 seconds to 60 seconds are required at a temperature of 300°C or higher. In the method of thermocompression bonding with a pair of hot press rolls as in the embodiment of the present invention, from the viewpoint of ensuring the productivity, the roll crimping is performed instantaneously within 10 seconds, so the reheating step after the thermocompression bonding step It becomes necessary to combine the annealing process of

In the reheating step (annealing treatment), it is necessary to heat treatment at a temperature equal to or higher than the _{lamination temperature (t 1 ).} If the temperature is below the lamination temperature (t ₁ ), the crystal structure of the partially recrystallized copper foil cannot be re-crystallized once in the thermocompression compression step, and the cube structure due to the crystal orientation of the (200) plane proceeds sufficiently. can't In other words, in order to sufficiently advance the partial recrystallization carried out by the lamination in the thermocompression bonding step, it becomes important to set _{the heat treatment temperature (t 2} ) of the reheating step to the lamination temperature (t _{1 ) or more.} In this case, when the temperature of the reheating step of the post step is 300°C or higher, a treatment time of about 10 seconds to 60 seconds is sufficient. On the other hand, when setting exceeding 400 degreeC, since problems, such as heat-resistance deterioration of a polyimide, and curvature by a heating, arise, it is preferable to set at 400 degrees C or less.

By passing through such a reheating step, the diffraction intensity (I) of the (200) plane obtained by X-ray diffraction in the thickness direction of the second copper foil after the thermocompression bonding step and (220) obtained by X-ray diffraction of fine powder copper ), the ratio (I/Io) of the diffraction intensity (Io) of the surface is in the range of 12 to 30. Moreover, by going through a reheating process, the average crystal grain diameter in the cross section of the thickness direction of a 2nd copper foil layer (B2) is controllable within the range of 40-70 micrometers.

The means of annealing in the reheating step is not limited, but considering that the continuously conveyed second copper foil and single-sided copper clad laminate are placed in a uniform temperature environment, one section of the process is a furnace-type booth, and heating with hot air is preferred. desirable. Moreover, it is preferable to use heating nitrogen for a hot air in order to prevent influence, such as a change of quality on the surface of copper foil. Since this heating with nitrogen has a limit in making the temperature condition higher, other heating means can be added. Preferred heating means include providing a heating heater in the vicinity of the conveying path. In addition, it is also possible to provide a plurality of heating heaters, and the type may be the same or different.

<FPC>

The flexible copper-clad laminate of this embodiment is mainly useful as an FPC material. That is, FPC which is one Embodiment of this invention can be manufactured by processing the metal foil of the flexible copper clad laminated board of this embodiment in pattern shape by a normal method, and forming a wiring layer.

The FPC of the present embodiment can be used as a wiring circuit component used for a bent or bent portion, and can be used as an FPC in which a wiring circuit used for the bent or bent portion is substantially formed only on one side. Preferably, a wiring circuit is formed using the 2nd copper foil layer (B2) of the flexible copper clad laminated board of this embodiment, and it is good to use at least a part of a wiring circuit as a bending part. That is, in the embodiment of the present invention, by forming the wiring circuit used in the bending or bending portion substantially only on one side, an FPC excellent in bending resistance such as repeated bending and folding can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the state of FPC for removing a part of 1st copper foil layer (B1) and forming a bent part. Although the 1st copper foil layer (B1) to remove changes also with the kind and use of FPC, the principal part (ie 80% or more) of the 1st copper foil layer (B1) is removed, As shown in FIG. 1, a wiring circuit It is good to make the 1st copper foil layer B1 remain only at the point which does not relate to the bending schedule part 10, without leaving the point which functions as.

When the wiring circuit formed by the 2nd copper foil layer B2 is bent, as for the FPC performed as mentioned above, you may make it located outside, and you may make it position inside. In addition, with respect to the bending portion formed in the FPC, in addition to being formed by folding in two, for example, a bending portion accompanying any repeated operation selected from sliding bending, bending bending, hinge bending, or sliding bending has excellent bending resistance. can indicate

As described above, the flexible copper-clad laminate of the present embodiment can provide a material for FPC that is excellent in connection reliability in a bent state in an electronic device since it can express the high bending resistance required for a wiring board. . Therefore, the flexible copper clad laminated board of this embodiment is especially preferably used for the electronic component by which bending resistance, such as a bending part around small liquid crystals, such as a smart phone, is calculated|required. Moreover, since the flexible copper clad laminated board of this embodiment has the performance which can withstand the intermittent repeated sliding required for a wiring board, and a copper foil layer advantageous in forming high-density wiring, the read light in a hard disk drive It is preferably used also as a material for FPC for cables.

Example

Hereinafter, the present invention will be described in more detail based on Examples. In addition, each characteristic evaluation in the following Example was implemented by the following method.

[Measurement of tensile modulus]

Regarding copper foil at the time of the measurement of tensile elasticity modulus, the copper foil which provided the heat processing equivalent to the processing process of a flexible copper clad laminated board using vacuum oven was used. Moreover, regarding the polyimide layer, the polyimide film which etched the flexible copper clad laminated board and removed copper foil completely was used. Thus, the value of the tensile elasticity modulus was measured for the material obtained in this way in the environment of the temperature of 23 degreeC, and 50% of relative humidity using the Toyo Seiki Seisakusho strograph R-1.

[Measurement of coefficient of thermal expansion (CTE)]

Using a thermomechanical analyzer manufactured by Seiko Instruments, the temperature was raised to 250 ° C., and further maintained at that temperature for 10 minutes, then cooled at a rate of 5 ° C./min., the average coefficient of thermal expansion from 240 ° C. to 100 ° C. (linear thermal expansion) coefficient) was calculated.

[Measurement of glass transition temperature]

The resin solution of polyamic acid was apply|coated on copper foil, it heat-processed, and it was set as the laminated body. The dynamic viscoelasticity of the polyimide film (10 mm × 22.6 mm) obtained by etching away the copper foil of this laminate was measured with a dynamic viscoelasticity measuring apparatus (DMA) from 20 ° C. to 500 ° C. at 5 ° C./min. , the glass transition temperature Tg (tanδ local maximum) was obtained.

[Measurement of the average grain size of the cross section in the thickness direction of copper foil]

A sample was prepared, the cross section of copper foil was formed along the longitudinal direction (MD direction) of copper foil by the IP (ion polish) method (cross section cut in the thickness direction), OIM (software Ver5.2 by TSL) ) was used to analyze the crystal grain size and orientation state of the copper foil cross section by EBSD (backscattered electron diffraction pattern method). The analysis was performed under the conditions of an acceleration voltage of 20 kV and a sample inclination angle of 70°, and the analysis range was analyzed with a width of 500 µm along the longitudinal direction of the copper foil. From the inverse pole viscosity orientation map obtained by the analysis, the grain size distribution analysis is performed under the condition that Σ3CSL (twin grain boundary) is a grain boundary and a grain boundary of 2 to 5° is not a grain boundary, and a weighted average is determined by the area ratio of the crystal. The particle size was calculated.

[Measurement of crystal orientation I/Io by XRD]

Regarding the crystal orientation of the (200) plane of the copper foil, the (220) plane diffraction intensity (Io) of the sample obtained by X-ray diffraction of fine powder copper by the XRD method using the Mo counter-cathode is the (200) plane of the sample. The diffraction intensity (I) was calculated and defined as the I/Io value.

[Measurement of surface roughness (Rz)]

The surface roughness of the contact surface side of copper foil and a polyimide insulating layer was measured using the contact type surface roughness measuring instrument (Co., Ltd. product SE1700).

[Measurement of etching factor]

A resist pattern (60 µm pitch circuit) of L/S = 50 µm/10 µm was formed on the copper foil surface with a film-like resist, etched with ferric chloride (liquid temperature 50° C., 0.2 MPa), and the circuit bottom width was 30 The etching factor (EF) was computed with respect to 10 circuits at the time of about micrometers, and the average value was calculated|required. The etching factor is the distance of the length of the deflection from the intersection of the vertical line from the width direction end of the upper surface of the circuit and the resin substrate, assuming that the circuit is etched vertically when the etching is spread out toward the end (when deflection occurs) is D, the ratio of this D to the thickness H of the copper foil: H/D, and the larger this numerical value is, the larger the inclination angle becomes. It means that the workability of The case where the value of this etching factor was 2.5 or more was evaluated as "good|favorableness", and the case where it was less than 2.5 was evaluated as "poor".

[Measurement of folding (bending test)]

A test piece (test circuit board piece) in which a copper foil of a copper clad laminate was etched, and 10 rows of copper wirings 51 having a length of 40 mm were formed along the longitudinal direction with a line width of 100 µm and a space width of 100 µm (40) ) was prepared ( FIG. 2 ). As shown in FIG. 2 showing only the copper wiring 51 in the test piece 40, the 10 rows of copper wiring 51 in the test piece 40 are all connected continuously through the U-shaped part 52, and electrode portions for resistance value measurement (not shown) are formed at both ends thereof.

The test piece 40 was fixed on the sample stages 20 and 21 which can be folded in two, the wiring for resistance value measurement was connected, and the monitoring of a resistance value was started (FIG. 3). The bending test was carried out by bending the copper wirings 51 of 10 rows so that the copper wirings 51 turned inside and opposed at the exact central portion in the longitudinal direction. At this time, using the roller 22 made of urethane, while controlling so that the gap H of the bending point 40C becomes 0.3 mm, the roller 22 is moved in parallel with the bent line, and 10 rows of copper wiring 51 After bending all the (Fig. 4 and Fig. 5), open the bent part to return the test piece 40 to a flat state (Fig. 6), and move the part where the fold is formed while pressing it with the roller 22 again. (FIG. 7), this series of steps was counted as one folding number. While the bending test is repeatedly carried out in this order, the resistance value of the copper wiring 51 is always monitored, and the point at which the predetermined resistance (3000 Ω) is reached is judged to be the breakage of the copper wiring 51, until that time. The number of repeated bending was taken as the folding measurement value. The case where this folding measurement value was 100 times or more was evaluated as "good", and the case where it was less than 100 times was evaluated as "poor".

In addition, in a bending test, when using the test piece 40 in the state bent from the beginning, the state in which the bending was canceled is made into zero bending frequency once, and the bending frequency is counted in the said order.

The manufacturing method of the flexible copper clad laminated board described in an Example and a comparative example is shown next.

[Synthesis of polyamic acid solution]

(Synthesis Example 1)

In a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen, put N,N-dimethylacetamide, and further 2,2-bis[4-(4-aminophenoxy)phenyl]propane in this reaction vessel (BAPP) was added and dissolved while stirring in a container. Next, pyromeltic acid dianhydride (PMDA) was injected|thrown-in so that the preparation total amount of a monomer might be set to 12 wt%. Then, stirring was continued for 3 hours, the polymerization reaction was performed, and the resin solution of the polyamic-acid a was obtained. The coefficient of thermal expansion (CTE) of the 25-micrometer-thick polyimide film formed from the polyamic acid a was 55x10<^-6> /K, and the glass transition temperature was 312 degreeC.

(Synthesis Example 2)

In a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen, put N,N-dimethylacetamide, and further 2,2'-dimethyl-4,4'-diaminobiphenyl (m -TB) was added and dissolved while stirring in a container. Next, 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) were added in a total amount of 15 wt% of monomers, and the molar ratio of each acid anhydride ( BPDA: PMDA) was added to be 20: 80. Then, stirring was continued for 3 hours, the polymerization reaction was performed, and the resin solution of the polyamic-acid b was obtained. The coefficient of thermal expansion (CTE) of the polyimide film with a thickness of 25 micrometers formed from the polyamic acid b was 7*10<^-6> /K, and the glass transition temperature was 385 degreeC.

(Synthesis Example 3)

In a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen, put N,N-dimethylacetamide, and further 2,2'-dimethyl-4,4'-diaminobiphenyl (m -TB) and 4,4'-diaminodiphenyl ether (DAPE) were added so that the molar ratio of each diamine (m-TB: DAPE) was 60: 40, and dissolved in a vessel while stirring. Next, pyromellitic dianhydride (PMDA) was injected|thrown-in so that the preparation total amount of a monomer might be 16 wt%. Then, stirring was continued for 3 hours, the polymerization reaction was performed, and the resin solution of the polyamic-acid c was obtained. The thermal expansion coefficient (CTE) of the polyimide film with a thickness of 25 micrometers formed from the polyamic acid c was 10x10<^-6> /K, and the glass transition temperature was 409 degreeC.

(Example 1)

As a first copper foil, the resin solution of the polyamic acid a prepared in Synthesis Example 1 was continuously coated and dried on an electrolytic copper foil having a thickness of 12 µm and a long electrolytic copper foil (HLB foil manufactured by Nippon Electric Co., Ltd.), and further synthesized thereon. The resin solution of the polyamic acid b prepared in Example 2 and the resin solution a were sequentially applied, and dried at 120°C for about 3 minutes. Then, finally 300 degreeC or more and heat processing for about 2 minutes were performed, the total film thickness of the polyimide layer was 12 micrometers, and the elongate single-sided flexible copper clad laminated board whose tensile elasticity modulus is 7 GPa was obtained. Next, with respect to the surface of the polyimide layer of this single-sided flexible copper clad laminated board, as a 2nd copper foil, a 12-micrometer-thick elongate rolled copper foil (HA foil manufactured by JX Nikko Niseki Metals Co., Ltd.) was thermocompression-bonded. As a laminating apparatus, a long base material to be laminated is conveyed from an unwinding shaft via a guide roll, and a pair of opposing metal rolls (surface roughness Ra = 0.15 µm) in a furnace under an inert atmosphere are heat-bonded. was applied. The thermocompression bonding conditions were a temperature of 360°C and a pressure of 130 Kg/cm, and a passage time of 2 to 5 seconds (lamination: thermocompression bonding step). Then, it heat-processed for 60 second in a 380 degreeC heating stove (reheating process), and obtained the double-sided flexible copper clad laminated board. The ratio of the thickness of the polyimide layer and the 2nd copper foil layer at this time was 1.0.

About the copper foil (referred to as "cast side copper foil") to which the resin solution of polyamic acid in the double-sided flexible copper clad laminated board obtained above was apply|coated, the average crystal grain diameter of the thickness direction cross section computed from EBSD analysis was 3.5 micrometers. , (T1) x (D1) = 42 µm 2 , and the etching factor was 3.0, showing good fine wiring workability. In addition, with respect to the copper foil laminated by the thermocompression bonding process (referred to as "laminated copper foil"), the tensile modulus of elasticity is 14 GPa, the average grain size of the cross section in the thickness direction calculated from the EBSD analysis is 56.7 µm, and X in the thickness direction The ratio I/Io of the (200) plane diffraction intensity (I) determined by ray diffraction and the (220) plane diffraction intensity (Io) determined by X-ray diffraction of fine powder copper was 18.5. The folding measurement value of FPC which wiring-formed by removing cast surface copper foil by etching and etching laminated surface copper foil was 148 times, and showed favorable bending resistance. A result is shown to Tables 1-3.

(Example 2)

As the second copper foil, it was carried out in the same manner as in Example 1 except that a long rolled copper foil having a thickness of 18 µm (HA foil manufactured by JX Nikko Nisseki Metals Co., Ltd.) was used, and the total film thickness of the polyimide layer was 12 µm, The tensile elastic modulus obtained the elongate double-sided flexible copper clad laminated board whose ratio of 7 GPa and the thickness of a polyimide layer and a 2nd copper foil layer is 1.5. In Tables 1-3, the average crystal grain diameter of the thickness direction cross section of a 1st copper foil layer, (T1)*(D1), and an etching factor were shown. Moreover, the tensile elastic modulus of a 2nd copper foil layer, the average crystal grain diameter of the cross section in the thickness direction, I/Io, and the folding measurement value of the FPC in which wiring was formed by etching laminated surface copper foil are shown collectively.

(Example 3)

It carried out similarly to Example 1 except having used the 12-micrometer-thick, elongate rolled copper foil (JX Nikko Niseki Metals Co., Ltd. HA-V2 foil) as a 2nd copper foil, and the total film thickness of the polyimide layer was 12 The elongate double-sided flexible copper clad laminated board whose micrometer, tensile modulus of elasticity is 7 GPa, and ratio of the thickness of a polyimide layer and a 2nd copper foil layer is 1.0 was obtained. In Tables 1-3, the average crystal grain diameter of the thickness direction cross section of a 1st copper foil layer, (T1)*(D1), and an etching factor were shown. Moreover, the tensile elastic modulus of a 2nd copper foil layer, the average crystal grain diameter of the cross section in the thickness direction, I/Io, and the folding measurement value of the FPC in which wiring was formed by etching laminated surface copper foil are shown collectively.

(Example 4)

As the 1st copper foil, it carried out similarly to Example 2 except having used the 18-micrometer-thick, elongate electrolytic copper foil (Furukawa Electric Industry Co., Ltd. F2-WS foil), the total film thickness of the polyimide layer was 12 micrometers, The tensile elastic modulus obtained the elongate double-sided flexible copper clad laminated board whose ratio of 7 GPa and the thickness of a polyimide layer and a 2nd copper foil layer is 1.5. In Tables 1-3, the average crystal grain diameter of the thickness direction cross section of a 1st copper foil layer, (T1)*(D1), and an etching factor were shown. Moreover, the tensile elastic modulus of a 2nd copper foil layer, the average crystal grain diameter of the cross section in the thickness direction, I/Io, and the folding measurement value of the FPC in which wiring was formed by etching laminated surface copper foil are shown collectively.

(Example 5)

As 1st copper foil, it carried out similarly to Example 1 except having used the 6-micrometer-thick, elongate electrolytic copper foil (Nippon Electric Co., Ltd. product SEED-S foil), and the total film thickness of a polyimide layer was 12 micrometers, and tensile The elastic modulus obtained the elongate double-sided flexible copper clad laminated board whose elasticity modulus 7 GPa and ratio of the thickness of a polyimide layer and a 2nd copper foil layer is 1.0. In Tables 1-3, the average crystal grain diameter of the thickness direction cross section of a 1st copper foil layer, (T1)*(D1), and an etching factor were shown. Moreover, the tensile elastic modulus of a 2nd copper foil layer, the average crystal grain diameter of the cross section in the thickness direction, I/Io, and the folding measurement value of the FPC in which wiring was formed by etching laminated surface copper foil are shown collectively.

(Example 6)

The resin solution of the polyamic acid a prepared in Synthesis Example 1 is continuously applied and dried on the copper foil, and the resin solution of the polyamic acid c prepared in Synthesis Example 3 and the resin solution of the polyamic acid a further thereon. was applied sequentially to form a polyimide layer having a total film thickness of 16 µm and a tensile modulus of 5 GPa of the polyimide layer. A long, double-sided flexible copper-clad laminate of 0.75 was obtained. In Tables 1-3, the average crystal grain diameter of the thickness direction cross section of a 1st copper foil layer, (T1)*(D1), and an etching factor were shown. Moreover, the tensile elastic modulus of a 2nd copper foil layer, the average crystal grain diameter of the cross section in the thickness direction, I/Io, and the folding measurement value of the FPC in which wiring was formed by etching laminated surface copper foil are shown collectively.

(Comparative Example 1)

As a 1st copper foil, on the 18-micrometer-thick, elongate rolled copper foil (JX Nikko Niseki Metal Co., Ltd. BHY-22B-T foil), in the same manner as in Example 1, resin solution a/resin solution b/resin solution a is sequentially applied and dried, and finally heat treatment is performed at 300 ° C. or higher for about 2 minutes to obtain a long, single-sided flexible copper clad laminate having a total film thickness of the polyimide layer of 12 µm and a tensile modulus of 7 GPa, and further 2 As the copper foil, a long electrolytic copper foil having a thickness of 6 μm (SEED-S foil manufactured by Nippon Electric Co., Ltd.) was used and the surface of the polyimide layer of the single-sided flexible copper-clad laminate was heat-compressed in the same manner as in Example 1. Then, it heat-processed for 60 second with a 380 degreeC heating stove, and obtained the double-sided flexible copper clad laminated board. The ratio of the thickness of the polyimide layer at this time and the 2nd copper foil layer was 0.5.

The average crystal grain diameter of the thickness direction cross section of the cast surface copper foil in the double-sided flexible copper clad laminated board obtained above was 10.0 micrometer, (T1)*(D1) =180 micrometers. The etching factor was 2.1, indicating that the fine wiring workability was not practically sufficient. In addition, the tensile modulus of the laminated copper foil is 55 GPa, the average grain size of the cross section in the thickness direction calculated from EBSD analysis is 1.8 µm, the diffraction intensity (I) of the (200) plane obtained by X-ray diffraction in the thickness direction, and Ratio I/Io of the (220) plane diffraction intensity (Io) calculated|required by X-ray diffraction of fine powder copper was 0.34. The measured folding value of the FPC in which the wiring was formed by removing the cast-surface copper foil by etching and etching the laminate-surface copper foil was 66 times, and showed insufficient bending resistance in practical use. A result is shown to Tables 1-3.

(Comparative Example 2)

As the first copper foil, a long rolled copper foil having a thickness of 12 µm (BHY-22B-T foil manufactured by JX Nikko Nisseki Metals Co., Ltd.) was used as the first copper foil, and an electrolytic copper foil having a thickness of 12 µm and an elongated shape (manufactured by Nippon Electric Corporation) was used as the second copper foil. HLB foil) was used, and the same procedure as in Example 1 was carried out, the total film thickness of the polyimide layer was 12 µm, the tensile modulus was 7 GPa, and the ratio of the thickness of the polyimide layer to the second copper foil layer was 1.0. A flexible copper-clad laminate was obtained. In Tables 1-3, the average crystal grain diameter of the thickness direction cross section of a 1st copper foil layer, (T1)*(D1), and an etching factor were shown. Moreover, the tensile elastic modulus of a 2nd copper foil layer, the average crystal grain diameter of the cross section in the thickness direction, I/Io, and the folding measurement value of the FPC in which wiring was formed by etching laminated surface copper foil are shown collectively.

(Comparative Example 3)

A double-sided flexible copper-clad laminate was obtained in the same manner as in Example 3 except that the surface of the polyimide layer of the single-sided flexible copper-clad laminate and the heat treatment in the heating stove after thermocompression of the second copper foil were removed. In Tables 1-3, the average crystal grain diameter of the thickness direction cross section of a 1st copper foil layer, (T1)*(D1), and an etching factor were shown. Moreover, the tensile elastic modulus of a 2nd copper foil layer, the average crystal grain diameter of the cross section in the thickness direction, I/Io, and the folding measurement value of the FPC in which wiring was formed by etching laminated surface copper foil are shown collectively.

(Comparative Example 4)

A double-sided flexible copper-clad laminate was obtained in the same manner as in Example 2 except that the surface of the polyimide layer of the single-sided flexible copper-clad laminate and the heat treatment in the heating stove after thermocompression of the second copper foil were removed. In Tables 1-3, the average crystal grain diameter of the thickness direction cross section of a 1st copper foil layer, (T1)*(D1), and an etching factor were shown. Moreover, the tensile modulus of elasticity of a 2nd copper foil layer, the average grain size of the cross section in the thickness direction, I/Io, and the folding measurement value of the FPC which wiring-formed by etching laminated surface copper foil are collectively shown.

As mentioned above, although embodiment of this invention was described in detail for the purpose of illustrating, this invention is not restrict|limited to the said embodiment

10: bending scheduled part
20, 21: sample stage
22: roller
40: test piece
40C: bending point of the specimen
51: copper wiring
52: U-shaped part of copper wiring

Claims (6)

A polyimide insulating layer (A), a first copper foil layer (B1) formed on one surface of the polyimide insulating layer (A), and a second copper formed on the other surface of the polyimide insulating layer (A) A flexible copper clad laminate having a thin layer (B2), comprising:
Configurations of a and b below:
a) The first copper foil layer (B1) has a surface roughness (Rz) of a surface in contact with the polyimide insulating layer (A) in a range of 0.7 to 2.5 µm, and a thickness (T1) in a range of 5 to 20 µm In the relationship between this thickness (T1) and the average grain size (D1) in the cross section in the thickness direction after thermocompression bonding, (T1) × (D1) is made of a copper foil in the range of 10.8 to 59 µm 2 thing ;
b) the second copper foil layer (B2) has a surface roughness (Rz) of a surface in contact with the polyimide insulating layer (A) in the range of 0.1 to 1.5 µm, and a thickness in the range of 5 to 20 µm, and tensile The elastic modulus is in the range of 10 to 25 GPa, the average grain size in the cross section in the thickness direction after thermocompression is within the range of 40 to 70 μm, and the diffraction intensity of the (200) plane obtained by X-ray diffraction after thermocompression bonding. What consists of copper foil whose ratio (I/Io) of (I) and the diffraction intensity (Io) of the (220) plane calculated|required by X-ray diffraction of fine powder copper exists in the range of 15.4-18.5;
A flexible copper clad laminate comprising a. The method of claim 1,
In addition, the configuration of c ;
c) Thickness exists in the range of 7-17 micrometers, and the said polyimide insulating layer (A) exists in the range whose tensile elasticity modulus in 25 degreeC is 2-9 GPa;
A flexible copper clad laminate comprising a. The method of claim 1,
In addition, the composition of d ;
d) the ratio of the thickness of the polyimide insulating layer (A) and the second copper foil layer (B2) [thickness of the second copper foil layer (B2)/thickness of the polyimide insulating layer (A)] is in the range of 0.48 to 2.4 what is mine;
A flexible copper clad laminate comprising a. The method of claim 1,
A flexible copper clad laminate used for a flexible circuit board that is folded and accommodated in a case of an electronic device by folding the upper surface side by inverting 180 degrees to become the lower surface side. The flexible circuit board which uses at least one part of wiring circuit for a bending part using the 2nd copper foil layer (B2) of the flexible copper clad laminated board in any one of Claims 1-4. 6. The method of claim 5,
The flexible circuit board from which the 1st copper foil layer (B1) of the position corresponded to at least a bending part is removed.

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