TW201500181A - Method for producing flexible copper-clad laminated plate - Google Patents

Abstract

This invention provides a flexible copper-clad laminated plate having excellent flexibility by an easy mean of using a pair of heat press rolls. The present invention provides a method for producing the flexible copper-covering laminated plate, which comprises a step of thermal compression bonding for thermally compression-bonding a copper foil (A) and a laminate (B) of polyimide films etc., with heating press rollers; and a step of reheating. The polyimide layers of the laminate (B) are composed of multiple polyimide layers having a thermoplastic polyimide layer (ii) as an adhesive layer. The laminating temperature of the step of thermal compression bonding T1 is the glass transition temperature of the thermoplastic polyimide layer (ii) or higher, and the heating temperature of the step of reheating T2 is set to be T1 or higher, whereby the diffraction intensity (I) of the (200) surface measured by X-ray diffraction along the thickness direction for the copper foil (A) after the step of thermal compression bonding, and the diffraction intensity (I0) of the (200) surface measured by X-ray for micro copper powders satisfy the formula: I/I0 >100.

Description

Method for manufacturing flexible copper clad laminate

The present invention relates to a method of manufacturing a flexible copper-clad laminate for use in a flexible circuit board, which is suitable for housing in a mobile phone, a smart phone, a tablet PC, or the like. The narrow space portion is bent into a folded curved shape or continuously reversely deflected with a small radius of curvature like a hard disk drive read/write cable. In addition, in the present invention, the upper side of the FPC is reversed by 180° C. and the lower side is bent to be placed in the thin frame. It is called "folding and bending".

In recent years, with the rapid development of miniaturization, thinning, and light weight of electronic devices represented by mobile phones, notebook computers, digital cameras, game machines, and the like, it is expected that even a material is used for materials using such devices. High-density, high-performance materials that house parts in a small space. In the flexible circuit board, the high-density and small-sized electronic devices such as smart phones and tablet PCs are becoming more and more popular, and the density of components is increasing. Therefore, it is necessary to store the flexible circuit board more narrowly than the current one. Inside the box. Therefore, even from the flexibility of the material belonging to the flexible circuit substrate In view of the material surface of the copper clad laminate, it is also necessary to improve the folding resistance and flexural resistance.

For these problems, it has been proposed to use a copper foil for a flexible copper-clad laminate in which a small amount of silver or tin is added for softening by annealing of a copper foil during heat treatment, and in some specific directions. (200 faces) A special rolled copper foil in which a cube assembly of a crystal orientation is developed (see Patent Document 1). Therefore, when the copper foil is subjected to the stress at the time of the deflection, the transition occurring in the crystal and the movement thereof are not accumulated in the crystal grain boundary, and the occurrence of cracks in the crystal grain boundary and the progress in the grain boundary can be suppressed. Destruction and excellent flexural properties.

Such a rolled copper foil cannot exhibit the aforementioned characteristics at normal temperature, and in order to develop such a cubic structure, it must be annealed by a predetermined heat treatment. The heat required for the annealing is, for example, a treatment at 150 ° C for 60 minutes, or a high temperature, and is completed at a temperature of about 300 ° C for about 1 minute.

In general, a method for producing a copper clad laminate comprising a polyimide and a copper foil is known in which a polyimide film is coated on a copper foil and dried, and subjected to high-temperature heat treatment to obtain a single-sided coating. a method of preparing a copper foil by thermal lamination after a copper laminate; preparing a polyimide film containing a thermoplastic polyimide in the outermost layer, and crimping it on both sides by thermal layering The way of copper foil. This thermal lamination method has an advantage that it is easy to introduce the apparatus by using a pair of opposed hot-pressing rolls. However, in such a method, since the heat input to the copper foil during the thermal lamination is a short time of about several seconds, it is not possible to obtain a rolled copper foil. The cubes are developed with enough heat.

Here, in order to improve the flexibility of the copper foil and to suppress defects such as microcracks or cracks, a method of annealing the copper foil by thermal lamination is known (refer to Patent Document 2). . However, the conditions of the annealing treatment shown here are only shown in a wide range of temperatures and times, and it is not clear whether or not the characteristics are specifically improved by how to anneal. Further, since the annealing treatment time shown in Patent Document 2 is set to be 2 minutes or longer, in addition to the insufficient productivity, the effect of the annealing treatment is focused on only the elastic modulus of the copper foil, and it has not been mentioned (200). The idea of cubic organization control such as surface crystallization alignment is difficult to cope with for the development of more severe flexing applications.

On the other hand, a method of manufacturing a flexible copper clad laminate which is different from the thermal lamination method by a hot roll has been disclosed as a method of performing thermal lamination using a plurality of rolls and a steel strip, which is also called a double belt ( Double belt) (refer to Patent Document 3). In this method, since the number of rolls and the like are easily increased, sufficient time for lamination can be ensured, but there are problems such as a large equipment cost.

[Advanced technical literature]

[Patent Literature]

[Patent Document 1] Japanese Patent No. 4285526

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2013-21281

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2011-270035

The present invention has been made in view of the above problems. The purpose of the invention is to provide a flexible copper-clad laminate having a heat-resistant and dimensionally stable polyimide as an insulating layer, and to provide excellent flexural properties by a pair of hot-pressing rolls. Flexible copper clad laminate.

In order to solve the above problems, the inventors of the present invention have found that the temperature T1 of the hot-pressing step of the pressure-bonded copper foil and the polyimide, and the temperature T2 of the reheating step of the post-heating are made to be in contact with the copper foil. The glass transition temperature (Tg) of the thermoplastic polyimide layer is set to T1 or more, and when T1 < T2, sufficient flexural characteristics can be exhibited, and the present invention has been completed.

That is, the method for producing a flexible copper-clad laminate according to the present invention comprises: heating a pressure-bonded copper foil (A) using a pair of hot press rolls, and providing an adhesive layer as a laminate with the copper foil (A) a step of heating and crimping the surface of the polyimide film or the metal layer of the polyimide layer (B); and, after that, further performing a heat treatment step, wherein the polyimide film or the The polytheneimide laminate (B) of the metal layer has a thermoplastic polyimide layer (ii) having a glass transition temperature of 260 ° C or higher as an adhesive layer, and the lamination temperature T1 of the above-mentioned thermocompression bonding step is the aforementioned thermoplastic polyimide. The glass transition temperature of the layer (ii) is equal to or higher than the heat treatment temperature T2 in the reheating step, and the copper foil (A) after the heating and pressure bonding step is in the thickness direction. The diffraction intensity (I) of the (200) plane obtained by X-ray diffraction, and the (200) plane diffraction intensity (Io) obtained by X-ray diffraction of fine powder copper The relationship is I/Io>100.

In the production method of the present invention, the heat treatment in the reheating step is preferably carried out under a vacuum or an inert (inactive) atmosphere, and the heat treatment temperature T2 is 300 ° C or higher, and the heating time is 10 seconds or longer.

Further, the polyimide film or the metal layer-containing polyimine laminate (B) preferably has a polyimine layer (i) and a thermoplastic polymer which have a low thermal expansion coefficient of a thermal expansion coefficient of less than 17 ppm/K. a plurality of polyimine layers of the quinone imine layer (ii).

Further, in the case of the copper foil (A), a rolled copper foil having a thickness of 5 to 100 μm is used in the preferred embodiment of the present invention.

According to the method for producing a flexible copper-clad laminate according to the present invention, the elastic modulus of the copper foil can be reduced by the reheating step (annealing treatment), and the specific alignment of the (200) plane can be performed to develop the cubic structure. As a result, Since the high bending resistance required for the wiring board is obtained, it is particularly suitable for bending resistance such as a bent portion around a small liquid crystal such as a smart phone, and an electronic circuit requiring continuous deflection such as a hard disk read/write cable. Device.

Hereinafter, the present invention will be described in detail.

The method for producing a flexible copper-clad laminate according to the present invention is a method of heating a pressure-bonded copper foil (A) and a polyimide film or a metal layer provided with an adhesive layer as a layer of the copper foil (A). Polyimide laminate (B), the heating crimp The middle system uses a pair of hot press rolls.

The hot press roll may be, for example, a metal roll or a resin-coated metal roll coated with a resin on the surface thereof, but a laminate of a copper foil (A) and a polyimide film or a metal layer-attached polyimide layer (B). (Lamination) is preferably carried out at a relatively high temperature, so that the heat resistance of the material used for the surface of the roll and/or the heat transfer from the inside of the roll to the surface is necessary, from this point of view. It is preferable that the metal roll has a surface roughness (Ra) of from 0.01 to 5 μm, particularly preferably from 0.1 to 3 μm.

In the present invention, the pressure-bonded copper foil (A) and the polyimide film or the metal layer-attached polyimide laminate (B) are introduced and heated between the pair of hot press rolls. In the present specification, this step is referred to as a heating and crimping step, and the object to be heated and pressure-bonded to the copper foil (A) is a polyimide film or a metal layer-containing polyimide layer (B), and is attached. An adhesive layer of a copper foil (A) and a polyimide film, or an adhesive layer of a copper foil (A) and a polyimide layer (B) attached to the metal layer.

The polyimine film (B) is only required to have an adhesive layer on the layer of the copper foil (A), and the film is a thermoplastic polyimide film having a glass transition temperature of 260 ° C or more. Further, for example, a polyimide film comprising a single layer of a non-thermoplastic polyimide layer or a plurality of polyimide layers having a thermoplastic polyimide layer having a glass transition temperature of 260 ° C or higher may be used. The polyimine film (B) may be prepared by a known method, and a commercially available polyimide film may also be used. A commercially available polyimide film can be exemplified by Kapton EN manufactured by Toray Dupont et al. In addition, the commercially available low thermal expansion polyimide film can also be coated to obtain thermoplastic A resin solution of the polyimine precursor of the polyimine layer (ii) and hardened.

Further, the polyimine laminate (B) with a metal layer may be, for example, a single layer or a plurality of layers of a polyimide layer provided on a metal foil such as a copper foil. When the polyimine is a single layer, the polyimide layer itself is an adhesive layer, so the polyimide needs to be formed from a thermoplastic polyimide layer (ii) having a glass transition temperature of 260 ° C or higher. When the amine is a plurality of layers, at least the surface of the copper foil (A) may be a thermoplastic polyimide layer (ii). The composition of the metal layer-containing polyimine laminate (B) can be exemplified by a metal layer/thermoplastic polyimide layer (ii)/low thermal expansion polyimine layer (i)/thermoplastic polyimide layer (ii), or a composition of the metal layer/low thermal expansion polyimine layer (i) / thermoplastic polyimide layer (ii). By forming the polyimine in the polyethylenimine laminate (B) with a metal layer as a plurality of layers, it is possible to satisfy the bonding strength, dimensional stability, solder heat resistance, etc. of the copper foil and the polyimide. As a feature required for flexible copper clad laminates. Further, the metal foil constituting the metal layer may be, for example, an aluminum foil or a stainless steel foil in addition to the copper foil.

More specifically, the polyethylenimine laminate (B) with the metal layer described above can be provided with a single-sided flexible copper clad laminate. The single-sided flexible copper-clad laminate can be used to form the low thermal expansion polyimine layer (i) or the polyimide polyimide precursor of the thermoplastic polyimide layer (ii) on the elongated copper foil. The resin solution is successively coated and dried, and is obtained by hardening (醯imination). One feature of the present invention is that a flexible copper-clad laminate can be continuously and efficiently produced by a simple method of a pair of hot-pressing rolls, from the viewpoint of forming a metal-coated polyimine laminate (B). A long strip can be used for the copper foil.

The copper foil of this form is sold by a copper foil manufacturer and has been wound into a roll, and this can be used. Further, according to the present invention, the copper foil of the flexible copper-clad laminate produced can be formed into a line formed by wire processing, and the deflection property of the copper foil can be maximized, and thus, even if it is first used as a single side The copper foil used in the case of the flexible copper clad laminate is preferably a rolled copper foil which is the same as the copper foil (A) which is heat-pressed by a pair of hot press rolls.

The low thermal expansion polyimine layer (i) and the thermoplastic polyimine layer (ii) constituting the polyimide layer are capable of ruthenium imidization of the polyamine which imparts the precursor of the properties. However, in general, the polyamic acid can be appropriately selected by blending the properties of the polyimine obtained by a known diamine and acid dianhydride, and then synthesizing it in an organic solvent. The resin viscosity to be polymerized is, for example, preferably in the range of 500 cps or more and 35,000 cps or less.

The diamine used as a raw material of the polyimide may, for example, be 4,6-dimethyl-m-phenyldiamine, 2,5-dimethyl-p-phenyldiamine, 2,4- Diamine mesitylene, 4,4'-methylenebis-o-toluidine, 4,4'-methylenebis-2,6-dimethylaniline, 4,4'-methylene-2 ,6-diethylaniline, 2,4-toluenediamine, m-phenyldiamine, p-phenyldiamine, 4,4'-diaminodiphenylpropane, 3,3'-diamine Diphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3 '-Diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenyl sulfide, 3,3' -diaminodiphenyl sulfide, 4,4'-diaminodiphenylanthracene, 3,3'-diaminodiphenylanthracene, 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'-dimethyl Oxybenzidine, 4,4'-diamino-p-terphenyl, 3,3'-diamino-p-terphenyl, bis(p-amine Cyclohexyl)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 - xylylene diamine, p-extended xylylene diamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4- Diazole, piperazine , 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,7-diaminodibenzofuran, 1,5-diaminopurine, dibenzo-p-di Alkane-2,7-diamine, 4,4'-diaminobenzyl, and the like.

Further, as the acid anhydride used as a raw material of the polyimine, for example, 1,2,4,5-benzenetetracarboxylic dianhydride, 3,3',4,4'-diphenyl ketone tetracarboxylic dianhydride, 2,2',3,3'-diphenyl ketone tetracarboxylic dianhydride, 2,3,3',4'-diphenyl ketone 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 acid Acid 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 acid Anhydride, 2,7-dichloronaphthalene-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-triphenyltetracarboxylic dianhydride , 2,2",3,3"-p-triphenyltetracarboxylic dianhydride, 2,3,3",4"-p-triphenyltetracarboxylic dianhydride, 2,2-dual (2 , 3-dicarboxyphenyl)-propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, double ( 2,3-dicarboxyphenyl) Dihydride, bis(3.4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)ruthenium anhydride, bis(3,4-dicarboxyphenyl)ruthenium anhydride, 1,1- Bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, hydrazine-2,3,8,9-tetracarboxylic acid Anhydride, indole-3,4,9,10-tetracarboxylic dianhydride, indole-4,5,10,11-tetracarboxylic dianhydride, indole-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 Alkane-1,2,3,4-tetracarboxylic dianhydride, pyridyl -2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-, 3,4,5-tetracarboxylic dianhydride, 4,4 '-Oxydiphthalic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, and the like.

The diamine and the acid anhydride may be used alone or in combination of two or more. In addition, examples of the solvent used for the polymerization include dimethylacetamide, N-methylpyrrolidone, 2-butanone, diethylene glycol dimethyl ether, xylene, etc., and one type or two types may be used in combination. the above.

In order to make the polyimine layer a low thermal expansion polyimine layer (i) having a thermal expansion coefficient of less than 17 × 10 ^-6 /K, the anhydride component as a raw material may also be used 1, 2, 4, 5- For the pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, diamine component, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2 -Methoxy-4,4'-diaminobenzoacetanilide, especially good can be 1,2,4,5-benzenetetracarboxylic dianhydride and 2,2'-dimethyl-4,4' - Diaminobiphenyl is a main component of each raw material component.

Further, in order to make the polyimide layer of the thermoplastic polyimide layer (ii) having a glass transition temperature of 260 ° C or higher, the anhydride is used as a raw material. 1,2,4,5-benzenetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ketone can also be used. 2,2'-bis[4-(4-aminophenoxy)benzene can be used as the tetracarboxylic dianhydride, 3,3',4,4'-diphenylphosphonium tetracarboxylic dianhydride or diamine component. Propane, 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene, especially good 1,2,4,5-benzenetetracarboxylic dianhydride 2,2'-bis[4-(4-aminophenoxy)phenyl]propane is a main component of each raw material component.

In the present invention, when a polyimide film is used or a polyimide layer with a metal layer is used, the surface of the copper foil (A) layer must be an adhesive layer. The layer is then composed of a thermoplastic polyimide layer (ii), but the glass transition temperature is 260 ° C or higher, preferably 280 ° C to 320 ° C. When the glass transition temperature of the thermoplastic polyimide layer (ii) is within this range, it is required between the copper foil and the polyimide surface which can be obtained when the flexible copper-clad laminate is processed into a flexible wiring substrate. The strength and dimensional stability are excellent, and the solder heat resistance required for solder bonding at the time of component packaging is excellent.

On the other hand, the low thermal expansion polyimine layer (i) is such that the thermal expansion coefficient of the entire polyimide layer is close to 12 to 23 ppm/K of the thermal expansion coefficient of the copper foil (A), preferably not The coefficient of thermal expansion of 17 ppm/K is more preferably in the range of 5 to 10 ppm/K. Thereby, the thermal expansion coefficient of the entire polyimide layer can be made to match the thermal expansion coefficient of the copper foil (A), and the warpage of the flexible copper-clad laminate and the dimensional change rate after heating after etching can be easily suppressed.

The copper foil (A) used for the production of the flexible copper clad laminate of the present invention is preferably a rolled copper foil. The rolled copper foil can be exemplified by hot press bonding and annealing in the subsequent step to add Ag in a crystal orientation of the (200) plane. And Sn as a copper alloy foil of an additive element. A well-known person can be exemplified by HA copper foil made of JX Nippon Mining Metal and HPF foil made of Hitachi wire. The thickness of the copper foil (A) is not particularly limited, but is generally in the range of 5 to 100 μm, preferably in the range of 7 to 50 μm, from the viewpoint of alleviating the stress attached to the copper foil during flexing. Preferably, it is in the range of 9 to 18 μm.

Next, the heating and crimping conditions of the copper foil (A) and the polyimide film or the metal layer-containing polyimine laminate (B) in the present invention will be described. The lamination temperature T1, that is, the temperature of the hot press roll in the heating and crimping step, must be a thermoplastic polyimide layer from the viewpoint of the adhesion of the copper foil (A) and the polyimine of the adhesive layer. (ii) The glass transition temperature of the polyimine is preferably from 300 to 400 °C. Further, it is desirable to heat the crimping under the condition that the line pressure between the heating rolls is 50 to 500 kg/cm and the roll passing time is 2 to 5 seconds. The laminated atmosphere can be exemplified by an atmospheric atmosphere and an inert atmosphere, but from the viewpoint of preventing oxidative discoloration of the copper foil, an inert atmosphere is desired. The inert atmosphere herein is synonymous with an inert atmosphere and is replaced by an inert gas such as nitrogen or argon and is substantially free of oxygen.

Here, the (200) plane crystal alignment by the heat treatment of the copper foil (A) will be described in detail. In general, the aforementioned copper foil is softened by heat treatment, and the modulus of elasticity is lowered and softened. The (200) plane is preferentially aligned and the cubic structure is developed. The crystal orientation of the (200) plane can be carried out at a temperature above the semi-softening temperature for a predetermined period of time, but must be at least at a temperature of 300 ° C or higher for 10 seconds to 60 seconds. According to the present invention, in the method of heating and crimping by a pair of hot press rolls, from the viewpoint of ensuring the productivity thereof, the press bonding by the rolls can be carried out instantaneously within 10 seconds, so that The heating and crimping step must be combined with the annealing step of the reheating step.

Here, the reheating step (annealing treatment) must be performed at a temperature higher than the lamination temperature T1. When the temperature is equal to or lower than the lamination temperature T1, the crystal structure of the copper foil which is partially recrystallized in the heating and pressure bonding step cannot be crystallized again, and the cubic structure cannot be sufficiently performed in the (200) plane crystal alignment. That is, in order to further carry out partial recrystallization by lamination in the heating and pressure bonding step, it is important to set the heat treatment temperature T2 of the reheating step to the lamination temperature T1 or more. At this time, the treatment time of about 10 seconds to 60 seconds is sufficient when the temperature of the reheating step of the subsequent step is 300 ° C or more. On the other hand, when the temperature exceeds 400 ° C, problems such as heat deterioration of the polyimide and warpage due to heating are caused, and therefore it is preferably set to 400 ° C or lower.

Through such a reheating step, the diffraction intensity (I) of the (200) plane obtained by the X-ray diffraction of the copper foil (A) after the heating and pressing step in the thickness direction can be obtained, and The relationship between the diffraction intensity (Io) of the (200) plane obtained by the X-ray diffraction of the fine powder copper becomes I/Io>100. Here, the I value and the Io value can be measured by the X-ray diffraction method, and the X-ray diffraction system in the thickness direction of the copper foil is used to confirm the alignment of the surface of the copper foil (the rolling surface when rolling the copper foil) The intensity (I) of the (200) plane indicates the intensity integral value of the (200) plane obtained by X-ray diffraction. Further, the strength (Io) is an intensity integral value of the (200) plane of the fine powder copper (copper powder of the Kanto Chemical Co., Ltd. grade I, 325 mesh, purity: 99.99% or more).

The annealing method in the reheating step is not limited, but it is considered to be a polyimine film or a metal layer-containing polyimine laminate which will be continuously conveyed. (B) Or the copper foil (A) is placed in a uniform temperature environment, preferably one of the steps is set as a furnace, and heated by hot air. Further, in order to prevent the deterioration of the surface of the copper foil or the like, the hot air is preferably heated with nitrogen. Heating with this nitrogen requires more temperature conditions, and since there is an upper limit, other heating means can be added. A preferred heating means can be exemplified by providing a heater beside the transport path. In addition, the heater may be provided in plural, and the types thereof may be the same or different.

[Examples]

Hereinafter, the present invention will be described in more detail based on examples. Further, in the following examples, each characteristic evaluation was carried out in the following manner.

[Measurement of crystal orientation I/Io by XRD]

The (200) plane crystal orientation of the copper foil was calculated by using the Mo-to-cathode XRD method for the (200) plane diffraction intensity (Io) obtained by X-ray diffraction of the fine powder copper (200). The surface diffraction intensity (I) is defined as the I/Io value.

[Measurement of deflection characteristics]

A commercially available photoresist film is bonded to a double-sided flexible copper clad laminate formed of a copper foil/polyimine/copper foil, and is exposed to a predetermined pattern to form a mask. The copper foil on the side of the photoresist film is completely etched away from the copper foil on the opposite side, and then the residual copper foil is formed into a pattern of L/S=100 μm/100 μm to form a resist layer (L: line width, S : Line line spacing is wide). Next, at the development hardening resist, the copper foil which is not required in the predetermined pattern formation is removed by etching, and the hardened resist layer is further removed by an alkaline liquid to prepare a test sample. After applying the cover layer to the test pattern, use the IPC test device to set the deflection radius r=1.5mm, stroke 25mm, slip The moving speed is 1500 cpm. The determination of the flex life was performed by applying a predetermined voltage to the sample and performing a flexural test. The sample having a resistance increase of 10% was regarded as a wire breakage as the number of deflections. In the following examples and comparative examples, the flexural properties of the cast copper foil on the cast surface (the removal of the laminated copper foil (substrate 2)) and the laminated copper foil (substrate 2) were evaluated. ) Flexural characteristics (removing coated copper foil) when a predetermined pattern is formed.

[Measurement of Solder Heat Resistance Test]

A commercially available photoresist film is bonded to a double-sided flexible copper-clad laminate formed of a copper foil/polyimine/copper foil, and is exposed in a predetermined pattern by a mask. The same location hardens to form a 1 mm circular patterned resist layer. Next, the hardening resist was developed, and an unnecessary copper foil layer was formed by etching in a predetermined pattern, and the hardened resist layer was further peeled off by an alkaline liquid to prepare a test sample. After the sample was dried, it was immersed in a solder bath having a different temperature for 10 seconds, and the temperature at which the copper foil did not swell or peel off was measured. This temperature was taken as the solder heat-resistant temperature.

[Measurement of peel strength]

A commercially available photoresist film is laminated on a laminate formed of a copper foil/polyimine/copper foil, and is formed in a predetermined pattern by exposure to a mask and then patterned to have a copper wiring width of 1 mm. Resistive layer. Next, at the development hardening resist, an unnecessary copper foil layer was formed by etching in a predetermined pattern, and the hardened resist layer was further peeled off by an alkaline liquid to prepare a test sample. After the sample was dried, the peel strength was measured by a 180° peeling method using a tensile tester (Strograph M-1) manufactured by Toyo Seiki Co., Ltd.

[Measurement of dimensional change rate]

The measurement of the dimensional change rate is carried out in the following order.

First, a dry film resist was exposed at intervals of 200 mm using a sample of 300 mm square (flexible copper clad laminate), and a target for position measurement was formed by development. Further, after measuring the size before the etching (normal state) in an atmosphere of a temperature of 23±2° C. and a relative humidity of 50±5%, the copper other than the target of the test piece is etched (the liquid temperature is 40° C. or less, and the time is within 10 minutes). To remove. After standing at an atmosphere of 23 ± 2 ° C and a relative humidity of 50 ± 5% for 24 ± 4 hours, the distance between the target sites was measured. The dimensional change rate in the normal state of each of the three directions in the longitudinal direction and the lateral direction was calculated, and the size after the etching was measured for each of the average values. Next, the test piece was heat-treated in an oven at 250 ° C for 1 hour, and the distance between the target positions after the measurement was measured. The dimensional change rate in the normal state of each of the three directions in the longitudinal direction and the lateral direction is calculated, and the average value of each is the dimensional change rate after the heat treatment. The rate of change in heating dimensionality is obtained by the following mathematical formula.

Dimensional change rate after etching (%) = (B-A) / A × 100

A; distance between targets after resist development

B; distance between targets after wiring formation

Heating dimensional change rate (%) = (D-C) / C × 100

C; distance between targets after wiring formation

D; distance between targets after heating

[Measurement of warpage]

A sheet of 10 cm × 10 cm size was formed from a flexible copper clad laminate, and when the sheet was placed on a table, the height of the table top separated from the highest portion of the table top was measured using a vernier scale. Set this height to the amount of warpage, and the amount of warpage is less than 2 mm. The time is evaluated as "no warping".

[Measurement of glass transition temperature]

A resin solution of polyamic acid was coated on the copper foil and heat-treated to form a laminate. The polyimine film (10 mm × 22.6 mm) obtained by etching away the copper foil of the laminate was subjected to DMA measurement of dynamic viscoelasticity at a temperature of 5 ° C / min from 20 ° C to 500 ° C to obtain a glass transition temperature Tg. (tan δ maxima).

[Measurement of thermal expansion coefficient]

The polyimide film obtained by etching the copper foil was heated to 250 ° C using a thermomechanical analyzer manufactured by Seiko Instruments Inc., and further kept at this temperature for 10 minutes, and then cooled at a rate of 5 ° C /min. Average coefficient of thermal expansion (linear thermal expansion coefficient) from 240 ° C to 100 ° C.

Next, a synthesis example of the polyamic acid used in the examples and comparative examples will be described.

(Synthesis Example 1)

In a reaction vessel equipped with a thermocouple and a stirrer while introducing nitrogen, N,N-dimethylacetamide was added, and 2,2-bis[4-(4-aminophenoxy) was introduced into the reaction vessel. Phenyl]propane (BAPP) is dissolved in a container while stirring. Next, 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) was put in such a manner that the total amount of the monomers charged was 12% by weight. Thereafter, the mixture was stirred for 3 hours to carry out a polymerization reaction to obtain a resin solution of polyamic acid a. The polyimine obtained from the polyamic acid a had a glass transition point temperature of 310 ° C and a linear thermal expansion coefficient of 45 ppm / K.

(Synthesis Example 2)

The reaction capacity of nitrogen can be introduced while having a thermocouple and a stirrer N,N-dimethylacetamide was added to the reaction vessel, and 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) was added to the vessel while stirring. Let it dissolve. Next, 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) to make the total amount of monomer input 15wt %, the molar ratio of each anhydride (BPDA: PMDA) was 20:80. Thereafter, the mixture was stirred for 3 hours to carry out a polymerization reaction to obtain a resin solution of polyglycolic acid b. The polyimine obtained from the polyaminic acid b had a glass transition point temperature of 380 ° C and a linear thermal expansion coefficient of 8 ppm / K.

(Synthesis Example 3)

In a reaction vessel equipped with a thermocouple and a stirrer while introducing nitrogen, N,N-dimethylacetamide was added, and 2,2-bis[4-(4-aminophenoxy) was introduced into the reaction vessel. Phenyl]propane (BAPP) is dissolved in a container while stirring. Next, 3,3',4,4'-diphenyl ketone tetracarboxylic dianhydride (BTDA) was put in such a manner that the total amount of the monomers charged was 12% by weight. Thereafter, the mixture was stirred for 3 hours to carry out a polymerization reaction to obtain a resin solution of polylysine c. The polyimine obtained from the polyaminic acid c had a glass transition point temperature of 240 ° C and a linear thermal expansion coefficient of 42 ppm / K.

(Example 1)

One side of a strip-shaped rolled copper foil (JX Nippon Mining & Metals HA foil; I/Io=7) having a thickness of 12 μm was uniformly coated and coated in Synthesis Example 1 so that the thickness after hardening was 2.2 μm. After the resin solution of polyamic acid a (first layer), it was dried by heating at 130 ° C to remove the solvent. Next, the resin solution (second layer) of the polyamic acid b prepared in Synthesis Example 2 was uniformly coated on the coated surface side so that the thickness after hardening was 7.6 μm, and dried at 135 ° C. Dry and remove the solvent. Further, a resin solution (third layer) of polylysine a which is the same as that of the first layer was uniformly applied to the coated surface side so as to have a thickness of 2.2 μm after curing, and dried by heating at 130 ° C to remove Solvent. In the continuous hardening furnace which is set to increase the temperature in stages from 130 ° C to 300 ° C, the long-length laminated body is heat-treated for about 6 minutes in total, and the thickness of the polyimide layer is 12 μm. Flexible copper-clad laminate (substrate 1).

Next, on the surface of the polyimide layer of the single-sided flexible copper-clad laminate (substrate 1), a strip-shaped rolled copper foil as a base material 2 is heated and pressure-bonded (JX Nippon Mining & Metal Co., Ltd. HA foil; I/Io=7). The laminating apparatus is suitable for conveying a long strip-shaped base material which is laminated by a roll by a roll, and a pair of opposite metal rolls in a furnace under an inert atmosphere (surface roughness Ra = 0.15 μm) ) The way of heating and crimping. The thermocompression bonding conditions were set to a temperature of 360 ° C, a pressure of 130 kg/cm, and a passage time; 2 to 5 seconds (lamination: heating and crimping step). Thereafter, the mixture was heated in a hot air oven at 380 ° C for 60 seconds (reheating step) to obtain a double-sided flexible copper clad laminate. Table 1, the substrate used in each example, the thermal lamination temperature, and the annealing conditions are shown in Table 1.

In the double-sided flexible copper-clad laminate obtained above, a copper foil coated with a resin solution of poly-proline (referred to as "casting surface copper foil") and a copper foil laminated by a thermocompression bonding step (Substrate 2: referred to as "laminated surface copper foil"), and Table 2 shows the diffraction intensity (I) of the (200) plane obtained by X-ray diffraction in the thickness direction, and The I/Io value of the (200) plane diffraction intensity (Io) obtained from the X-ray diffraction of the fine powder copper. Further, the flexural characteristics and the solder heat resistance are shown in Table 2. Casting surface copper foil (200 faces) I/Io is 195. The number of deflections obtained by the IPC test was 17 million. On the other hand, the laminated copper foil (200 surface) I/Io was 185, and the number of deflections obtained by the IPC test was 16 million times, and it had the same flexural characteristics as the copper foil of the casting surface. In addition, the solder heat resistance temperature is 350 ° C, which is a practically sufficient level.

(Example 2)

In the case of the copper foil used for the base material 1 and the copper foil used as the base material 2, a rolled copper foil (HPF-ST-X manufactured by Hitachi Metal Co., Ltd.) having a thickness of 12 μm each having a different strip shape was used. In the same manner, a double-sided flexible copper clad laminate was obtained. The evaluation results of the obtained double-sided flexible copper clad laminates are shown in Table 2. The (200 faces) I/Io of the cast copper foil was 205, and the number of deflections obtained by the IPC test was 16 million. On the other hand, the (200 surface) I/Io of the laminated copper foil was 200, and the number of deflections obtained by the IPC test was 17 million times, and the flexural characteristics equivalent to those of the cast surface were obtained. Further, the solder heat resistance temperature was 350 °C.

(Example 3)

On both sides of a commercially available polyimine film (Kapton EN), the resin solution of polyamic acid a synthesized in Synthesis Example 1 was coated and dried, and then hardened in an atmosphere to obtain a polymer containing thermoplastic polyimide. A quinone imine film (substrate 1). The copper foil (substrate 2) shown in Example 1 was thermally laminated on the both sides of the polyimide film at the temperature of 360 ° C in the same manner as in Example 1, and then heated at 380 ° C by a hot air oven. The heat treatment was performed for 1 minute to obtain a double-sided flexible copper-clad laminate. The evaluation results of the obtained double-sided flexible copper clad laminates are shown in Table 2. The (200 surface) I/Io of the copper foil on the laminated surface side was 198, and the number of deflections obtained by the IPC test was 13 million times. solder The heat resistant temperature was 320 °C.

(Comparative Example 1)

After the single-sided copper-clad laminate (substrate 1) was produced in the same manner as in Example 1, the copper foil (base material 2) shown in Example 1 was used, and the lamination conditions were carried out under the conditions shown in Table 1. Thereafter, the heat treatment in the reheating step was not performed, and the double-sided flexible copper clad laminate of Comparative Example 1 was obtained. The evaluation results of the obtained double-sided flexible copper clad laminates are shown in Table 2. The (200 faces) I/Io of the cast copper foil was 195, and the number of deflections obtained by the IPC test was 17 million. On the other hand, the (200 faces) I/Io of the laminated copper foil was 87, which did not reach about half of the cast face copper foil or the laminated copper foil of the example, and the number of deflections obtained by the IPC test was 700. Ten thousand times, it is 50% or less of the embodiment.

(Comparative Example 2)

A double-sided flexible copper clad laminate of Comparative Example 2 was obtained in the same manner as in Example 1 except that the laminating temperature T1 of the heating and pressure bonding step was 380 ° C, and the reheating step was carried out at 350 ° C for 60 seconds. . The evaluation results of the obtained double-sided flexible copper clad laminates are shown in Table 2. The (200 faces) I/Io of the cast copper foil was 195, and the number of deflections obtained by the IPC test was 17 million. On the other hand, the (200 faces) I/Io of the laminated copper foil was 90 without lifting from lamination, and the number of deflections obtained by the IPC test was 7.6 million.

(Comparative Example 3)

A double-sided flexible copper clad laminate of Comparative Example 3 was obtained in the same manner as in Example 1 except that the laminating temperature T1 of the heating and pressure bonding step was 380 ° C, and the reheating step was performed at 350 ° C for 600 seconds. . The evaluation results of the obtained double-sided flexible copper clad laminates are shown in Table 2. Even if it is extended At the time of the heating step, the (200 faces) I/Io of the laminated surface copper foil was 89, and the number of deflections obtained by the IPC test was 7.2 million times.

(Comparative Example 4)

When the single-sided flexible copper-clad laminate of the substrate 1 is obtained, instead of the poly-lysine used in the first layer and the third layer of the first embodiment, the poly-proline c shown in Synthesis Example 3 is used. A double-sided flexible copper clad laminate of Comparative Example 4 was obtained in the same manner as in Example 1. The evaluation results of the obtained double-sided flexible copper clad laminates are shown in Table 2. The laminated surface copper foil (200 faces) I/Io was raised to 189, and the number of deflections obtained by the IPC test was 15.5 million times, which was equivalent to that of the cast surface copper foil, but the solder heat resistance was 250 ° C. Resist the level of solder reflow, etc. when packaging parts.

Further, the peel strength, dimensional change rate, and warpage of the flexible copper clad laminate after the present embodiment were evaluated, but the peel strength of any of the examples was 0.8 kN/m. The dimensional change rate and the heating dimensional change rate after etching are all within 0.1%, and the warpage is also 2 mm or less. That is to say, the characteristics required for the flexible copper clad laminate can be maintained, and it is confirmed that there is no problem in practical use.

Claims (4)

A method for producing a flexible copper-clad laminate, comprising: heating a pressure-bonded copper foil (A) using a pair of hot-pressing rolls, and providing an adhesive layer as a layer of the copper foil (A) a heat-clamping step of the quinone imine film or the metal layer-containing polyimine laminate (B); and, thereafter, a heat treatment further reheating step, wherein the polyimine film or metal layer The polyimine laminate (B) has a thermoplastic polyimide layer (ii) having a glass transition temperature of 260 ° C or higher as an adhesive layer, and the lamination temperature T1 of the above-mentioned heat-bonding step is the aforementioned thermoplastic polyimide layer ( Ii) The glass transition temperature or higher, the heat treatment temperature T2 in the reheating step is set to be equal to or higher than the lamination temperature T1, whereby the thickness of the copper foil (A) after the heating and pressing step is X. The relationship between the diffraction intensity (I) of the (200) plane obtained by the line diffraction and the diffraction intensity (Io) of the (200) plane obtained by the X-ray diffraction of the fine powder copper is I/Io>100. . The method for producing a flexible copper-clad laminate according to the first aspect of the invention, wherein the heat treatment in the reheating step is carried out under vacuum or an inert atmosphere, and the heat treatment temperature T2 is 300 ° C or higher, and the heating time is More than 10 seconds. The method for producing a flexible copper-clad laminate according to claim 1 or 2, wherein the polyimide film or the metal layer-containing polyimide laminate (B) has a coefficient of thermal expansion a plurality of low thermal expansion polyimine layers (i) and thermoplastic polyimine layers (ii) of 17 ppm/K Polyimine layer. The method for producing a flexible copper-clad laminate according to any one of claims 1 to 3, wherein the copper foil (A) is a rolled copper foil having a thickness of 5 to 100 μm.