JPH09136379A - Flexible copper-clad laminated sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flexible copper-clad laminated sheet having simultaneously various characteristics required in application for a high density mounting material and a high performance adhesive as an intermediate layer by forming the intermediate layer between a base film layer and a conductive body layer with a thermoplastic resin with a specified glass transition temp., a specified water absorption and a specified dielectric const. SOLUTION: A flexible copper-clad laminated sheet is constituted of a base film layer consisting of a heat-resistant resin, an intermediate layer consisting of a thermoplastic resin simultaneously having a glass transition temp. of 100-250 deg.C, a water absorption of at most 1% and a dielectric const. of at most 3 and a conductive body layer consisting of an electrically good conductor. In this case, as the thermoplastic resin, a thermoplastic polyimide resin is used from the balance of various characteristics such as heat resistance and radiation resistance. This thermoplastic polyimide resin exhibits excellent adhesive properties by performing lamination at a temp. being close to its glass transition temp. or at a higher temp. than it and exhibits excellent adhesive properties by hot contact bonding at relatively low temp.- short time. In addition, during storing, there exists no possibility of moisture absorption in the intermediate layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible copper clad laminate, and more specifically, a flexible copper having an intermediate layer of a thermoplastic resin having excellent heat resistance and adhesiveness, and particularly low water absorption and low dielectric properties. It relates to a laminated laminate.

[0002]

2. Description of the Related Art In recent years, electronic devices have become more sophisticated, have higher performance,
Miniaturization is advancing, and miniaturization and weight reduction are also demanded for electronic components used with them. Therefore, semiconductor device packaging methods and wiring boards for mounting them have also been required to have higher density, higher functionality, and higher performance. In order to meet this demand, flexible printed circuit boards (hereinafter referred to as FPCs) have been subjected to thin-line processing, multilayer formation, etc., and component mounting FPCs in which components are directly mounted on FPCs and double-sided FPCs in which circuits are formed on both sides. , Or a high density F such as a multi-layer FPC in which a plurality of FPCs are laminated and the layers are connected by wiring.
PC has appeared.

By the way, the FPC basically has a structure in which a circuit pattern is formed on a flexible and thin base film and a cover lay is applied to the surface thereof, in order to obtain the densified FPC as described above. Is required to improve the performance of insulating adhesives and insulating organic films used as the materials. High heat resistance, especially when used as high-density packaging materials such as LOC (lead-on-chip) packages and MCMs (multi-chip modules), printed wiring board materials such as multilayer FPC, and aerospace materials. It is required to have mechanical strength, excellent workability and adhesiveness, particularly low hygroscopicity, and various other characteristics such as electrical characteristics and dimensional stability.

At present, as an organic insulating material used as a base film or a cover lay film for an FPC, a film made of a polyimide resin having high heat resistance and mechanical strength and excellent electrical characteristics is used. It is preferably used.

However, the polyimide resin is almost infusible and insoluble in the ring-closed state, and there are almost no application examples as an adhesive. As an insulating adhesive used in such applications, workability at low temperature (180 ° C. or lower) is possible. Epoxy resin and acrylic resin are often used because of their excellent workability. However, these adhesives have inferior properties such as heat resistance as compared with polyimide, and for example, high temperature (2
If the temperature is higher than 50 ° C.), the adhesive deteriorates, and there is a problem that the characteristics of the polyimide used as the base film cannot be fully utilized. Furthermore, post-curing for a long time is required, and there is a strong demand for a higher-performance adhesive for the above-mentioned high-density packaging material applications.

Therefore, in order to solve such a problem, an example in which a polyimide-based adhesive is used as an adhesive has recently been proposed. For example, Japanese Patent Laid-Open No. 2-1387
In No. 89, an adhesive film obtained from a resin composition obtained by mixing an aromatic polyimide obtained from 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and an aromatic diamine and a polymaleimide is used, A method of manufacturing an FPC in which a base material such as a film and a copper foil are bonded to each other has been proposed. In addition, JP-A-5-179224 and JP-A-5-11
No. 2768 proposes various thermoplastic polyimide adhesive materials which can be pressure-bonded by heating and pressing.

These polyimide-based adhesives are adhesives having excellent melt flowability, excellent adhesiveness when heated and pressed, and excellent heat resistance. They are polyimide films used as base films for FPCs. It has been attracting attention as an adhesive that can fully exhibit the above characteristics.

[0008]

However, although these polyimide-based adhesives have excellent melt flowability of polyimide and can be used as adhesives, these adhesives require high temperature and long time for adhesion. That is, there is a problem that the bonding cannot be performed unless the temperature is increased to 300 ° C. or higher. Further, there is a problem that these polyimide-based adhesives easily absorb moisture and have poor electrical characteristics after absorbing moisture.

That is, these adhesives easily absorb moisture due to moisture in the air, and have poor electrical characteristics during storage, so that it is difficult to store them in a polyimide state. Therefore, these adhesives cannot be supplied as, for example, a film-like adhesive sheet, and when used as an adhesive, a solution of a polyamic acid which is a precursor thereof is used as a base film or a coverlay film at the time of use. A step of forming an adhesive layer by coating on an insulating film, drying and then heating to imidize was required. Therefore, it is necessary to use FPC with polyimide adhesive.
However, there is a problem that it is difficult to reduce the manufacturing time when manufacturing such products. The process of forming the adhesive layer at the time of use is troublesome, and a method for further simplifying the production of the FPC or the like is required.

Further, in order to manufacture an FPC, after the adhesive layer is formed on the base film in this way, the base film layer on which the adhesive layer is formed and the copper foil or the like are superposed at 300 ° C. or higher. Heat-press to make a copper clad laminate,
After that, a copper foil or the like is etched to form a circuit, and a coverlay film is attached through several steps, but the adhesive layer sometimes absorbs moisture during the manufacturing process of the FPC. As a result, the electrical characteristics of the adhesive layer may be deteriorated, which may cause deterioration of the quality of the final product.

In view of such circumstances, the inventors of the present invention have solved the above-mentioned problems and have a flexible copper clad laminate having an intermediate layer of a high-performance adhesive having various properties required for high-density mounting material applications. As a result of earnestly researching for the purpose of providing a thermoplastic polyimide resin having sufficient heat resistance, processability and adhesiveness, and particularly low water absorption and low dielectric properties. That is, the present invention was found.

[0012]

The gist of a flexible copper-clad laminate according to the present invention is that it has a base film layer made of a heat-resistant resin and a glass transition temperature of 100 ° C to 2 ° C.
The temperature is 50 ° C., and the intermediate layer is made of a thermoplastic resin having a water absorption of 1% or less and a dielectric constant of 3 or less, and a conductor layer made of a good electrical conductor.

In the flexible copper clad laminate, the thermoplastic resin is represented by the general formula (1):

[0014]

[Chemical 6]

And the general formula (2)

[0016]

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(Wherein R ₁ and R ₂ are divalent organic groups, R ₃
Represents an organic group selected from hydrogen, a methyl group and a phenyl group, and n is an integer of 1 to 4. Also, X is

[0018]

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It is a trivalent linking group selected from ) And / or at least one of the block units.

Further, R ₁ in the general formulas (1) and (2) is

[0021]

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It is at least one selected from the group of divalent organic groups shown in.

Further, R ₂ in the general formula (1) is

[0024]

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It is at least one selected from the group of divalent organic groups shown in.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION A flexible copper clad laminate according to the present invention will be described below. Flexible copper clad laminate of the present invention, a base film layer made of a heat resistant resin,
Glass transition temperature is 100 ° C to 250 ° C, and further 1%
It is composed of an intermediate layer made of a thermoplastic resin having the following water absorption rate and a dielectric constant of 3 or less, and a conductor layer made of an electrically good conductor, and the thermoplastic resin used as the intermediate layer is characterized.

The thermoplastic resin is not particularly limited as long as it has a glass transition temperature of 100 to 250 ° C. and a water absorption of 1% or less and a dielectric constant of 3 or less. However, a thermoplastic polyimide resin is preferable from the viewpoint of balance of various properties such as heat resistance and radiation resistance. In particular, the compound of general formula (1) 11

[0028]

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And the general formula (2)

[0030]

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(Wherein R ₁ and R ₂ are divalent organic groups, R ₃
Represents an organic group selected from hydrogen, a methyl group and a phenyl group, and n is an integer of 1 to 4. Also, X is

[0032]

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It is a trivalent linking group selected from: ) A polyimide resin having a specific structure consisting of both or at least one of block units represented by, that is, a polyamic acid polymer, a polyimide polymer or a polyisoimide polymer resin is preferably used, and specifically, it can be obtained by the following method. You can

That is, in an atmosphere of an inert gas such as argon or nitrogen, the general formula (3) NH ₂ —R ₂ —H ₂ N (3) (in the formula, R ₂ represents a divalent aromatic group) And at least one diamine represented by the general formula (4)

[0035]

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(Wherein R ₃ represents hydrogen, a methyl group or a phenyl group, and n is an integer of 1 to 4), or a mixture of at least one diamine represented by the general formula ( Either 3) or the diamine represented by the general formula (4) is dissolved or diffused in an organic solvent. In this solution, the compound of general formula (5)

[0037]

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By adding at least one ester acid dianhydride represented by the formula (wherein R ₁ represents a divalent organic group) in a solid state or in an organic solvent solution, and reacting A solution of the polyamic acid polymer having the above specific structure is obtained. The reaction temperature at this time is preferably -10 ° C to 50 ° C, more preferably -5 ° C to 20 ° C. The reaction time is 30 minutes to 6 hours.

In this reaction, contrary to the above-mentioned addition procedure, first, the ester dianhydride is dissolved or diffused in an organic solvent, and a solution or slurry of the diamine in the solid or organic solvent is added to the solution. You may.

Examples of the organic solvent used in such a reaction include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, and N, N-. Examples thereof include acetamide-based solvents such as dimethylacetamide and N, N-diethylacetamide. These may be used alone or as a mixed solvent of two or three or more. Further, it can be used as a mixed solvent with a non-solvent of polyamic acid such as acetone, methanol, ethanol, isopropanol, benzene and methyl cellosolve together with these polar solvents.

As the diamine compound represented by the above general formula (3) used here, essentially various diamines can be used. More specifically, from the balance of various characteristics, the general formula ( R _{2 in} 3) is

[0042]

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It is more preferable that the main component is a diamine which is a divalent organic group selected from These substituents R ₂ are selected in terms of electron affinity pKa. The diamine specified by R ₂ may be used alone or as a mixture of two or more kinds.

As the diamine compound represented by the above general formula (4),

[0045]

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As shown in (4), it can be obtained by synthesizing a Na salt from a nitrophenol derivative, then reacting it with an alkyl halide to give a dinitro compound, and further reducing it with palladium activated carbon. In addition, R ₃ in the general formula (4) is selected from hydrogen, a methyl group, and a phenyl group, and the position of the amino group may be any of the ortho, meta, and para positions. The obtained diamine compound is 1
They may be used in one kind or as a mixture of two or more kinds.

As the ester dianhydride represented by the above general formula (5), ester dianhydrides having essentially any structure can be used, but more specifically,
From the balance of various characteristics, R ₁ in the general formula (5) becomes

[0048]

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It is more preferable that the main component is an ester dianhydride which is a divalent organic group selected from The ester dianhydride specified by R ₁ may be used alone or as a mixture of two or more kinds.

The polyamic acid polymer solution thus obtained is formed into a film and thermally or chemically dehydrated and ring-closed (imidized) to be preferably used as the intermediate layer in the present invention. A film made of a polyimide polymer having a specific structure is obtained.

Specifically, thermal dehydration ring closure (imidization)
In the method, a solution of the polyamic acid polymer obtained above is cast or coated on a support plate, an organic film such as PET, a metal film such as an aluminum foil, a support such as a drum or an endless belt to form a film. After being formed, it is dried to obtain a self-supporting film. This drying is 150
It is preferable to carry out the treatment at a temperature of not more than 0 ° C for about 5 to 90 minutes. Then, this is further heated, dried and imidized to obtain the polyimide film having the above-mentioned specific structure used as the intermediate layer in the present invention. The heating temperature for imidization is preferably in the range of 150 to 350 ° C, and particularly preferably 200 to 250 ° C. There is no limitation on the rate of temperature increase during heating, but it is preferable that the maximum temperature reaches the above temperature by gradually heating. The heating time varies depending on the thickness of the film and the maximum temperature, but is generally preferably in the range of 10 seconds to 10 minutes after the maximum temperature is reached. When the film having self-supporting properties is heated, it is preferable to peel it off from the support, fix the ends in this state and heat it, since a polyimide polymer having a small linear expansion coefficient can be obtained.

Further, in the method of chemically performing dehydration ring closure (imidization), when a dehydrating agent in a stoichiometric amount or more and a catalytic amount of a tertiary amine are added to the solution of the polyamic acid polymer to thermally dehydrate A desired polyimide film can be obtained by treating in the same manner as in. The dehydrating agent may be acetic anhydride, and the tertiary amine used as a catalyst may be pyridine, α-picoline, β-picoline, γ.
-Picoline, trimethylamine, triethylamine, isoquinoline and the like are preferred.

The chemical method is a method of imidizing without applying heat, but it takes several hours at room temperature to complete imidization. Therefore, when a chemical method is usually used, a thermal method is required. A method of using them together is used. In this case, the drying time for obtaining the self-supporting film and the heating time for completing the imidization can be shorter than in the case of only the thermal method.

In addition, as a method for obtaining a film made of a polyimide resin used as an intermediate layer in the present invention, the polyamic acid polymer solution is used in the form of a film,
It may be produced by imidizing a lump, powder or other shape without limitation, dissolving it in an organic solvent to obtain a polyimide solution, applying the solution on a metal foil, and drying the solvent.

Further, in order to obtain a film made of a polyisoimide polymer, the above-mentioned reactants in the polyimide formation, that is, diamine and tetracarboxylic dianhydride are converted into diimide such as dichlorocarbodiimide (DCC) and trifluoroacetic acid. After replacing with carboxylic acid,
The same reaction as that for obtaining the film made of the polyimide polymer may be performed.

By such a reaction, a film-shaped polyimide resin comprising the block unit represented by the general formula (1) and / or the block unit represented by the general formula (2), which is preferably used as an intermediate layer in the present invention, is obtained. Be done.

The number of repeating block units represented by the general formulas (1) and (2) is 0 or an integer of 1 or more, but the glass transition temperature is 100 to 250 ° C. and the low water absorption is 1% or less. In order to develop a dielectric constant of 3 or less, the sum of the number of repetitions of each block unit must be 1 or more. Further, the number of repetitions of each block unit is preferably 15 or less. If the number of repetitions exceeds 15, the copolymerization ratio will be biased and the effect of copolymerization will be small. Specifically, the glass transition temperature will be too high and low-temperature adhesion will be difficult to recognize.
This also contributes to imparting self-supporting properties to the film.

The molecular weight of the polyimide resin is not particularly limited, but in order to maintain the strength of the intermediate layer made of the obtained polyimide resin, the number average molecular weight of 50,000 or more, Is preferably 80,000 or more, particularly preferably 100,000 or more, and further preferably 120,000 or more. Note that it is difficult to directly measure the molecular weight of the polyimide polymer, and the description regarding the molecular weight of the polyimide in the present invention is an estimation based on the measured value obtained by an indirect method. That is, in the present invention, the value corresponding to the molecular weight of the precursor polyamic acid is the molecular weight of the polyimide.

The film made of the polyimide resin having the above-mentioned specific structure thus obtained has excellent heat resistance, which is a characteristic of polyimide, and has a composition of 1
It has a clear glass transition temperature between 00 and 250 ° C., and shows a heat fusion property by laminating at a temperature close to the glass transition temperature, and heat fusion at a relatively low temperature is possible. In addition, the water absorption rate under the condition of being immersed in pure water at 20 ° C for 24 hours shows an excellent low water absorption rate of 1% or less, and further, the dielectric constant at 1 MHz in the Q meter method is 3 or less, which is an excellent low dielectric constant. Show the characteristics. In addition, this polyimide resin has a high viscosity, the obtained film also exhibits sufficient mechanical strength, and, in addition, exhibits excellent radiation resistance.

That is, the polyimide resin having the above specific structure has excellent heat resistance, thermoplasticity, adhesiveness, low water absorption property,
It has the characteristics of having both low dielectric properties and radiation resistance, and can be suitably used as an intermediate layer of the flexible copper-clad laminate of the present invention. In particular, due to these excellent low water absorption characteristics and dielectric characteristics, a flexible copper clad laminate using such an intermediate layer can be suitably used as an electric circuit component material or the like that should be compatible with future high-density mounting applications. . The mechanism of manifestation of the low water absorption property and the low dielectric constant property is not clear, but it is presumed that the bias of the electrons is reduced by the ester group close to the five-membered imide ring.

Then, the film made of the thermoplastic polyimide polymer is used as an intermediate layer, which is inserted between the base film and a conductor layer such as a copper foil so as to be triple-layered and thermocompression-bonded. A flexible copper clad laminate can be obtained.

The base film referred to in the present invention is FP.
Any film may be used as long as it can be used as a base film such as C, but a polyimide film having excellent heat resistance is particularly preferably used. Specifically, as the polyimide film used as the base film, for example, a polyimide film having no adhesiveness such as “Apical (registered trademark; manufactured by Kaneka Kagaku Kogyo Co., Ltd.)” can be used, but any other structure can be used. It may be a polyimide film.

As another method for obtaining the flexible copper-clad laminate of the present invention, a film made of the polyimide resin is laminated on both sides or one side of a base film and thermocompression bonded to prepare a bonding sheet, You may heat-press by laminating copper foil on both sides or one side.

In addition, the flexible copper-clad laminate of the present invention does not use a film made of a polyimide resin as an intermediate layer as described above, but uses a solution of a polyamic acid polymer as its precursor on both sides of the base film. Alternatively, it can be obtained by casting and coating on one side to imidize it, and then stacking copper foil on both sides or one side and heating and pressure bonding. On the contrary, the polyamic acid solution is cast or coated on a copper foil, and after imidization, the coated surface and the polyimide film are superposed and heat-pressed, or the coated surface is thermosetting. The production method is not limited, such that a polyamic acid solution may be cast or applied and imidized to form a polyimide film.

The polyimide resin having the above-mentioned specific structure used as the intermediate layer in the present invention is a thermoplastic resin such as nylon, polyvinyl acetate, polyvinyl chloride, polytetrafluoroethylene or polymethylmethacrylate, a filler or a glass. A resin composition may be prepared by blending fibers and the like, and thereby various properties such as mechanical strength and adhesiveness can be improved.

The flexible copper-clad laminate according to the present invention thus obtained has a glass transition temperature of 100 to 25.
The base film and the conductor layer are firmly adhered by an intermediate layer made of a polyimide resin having a specific structure having a water absorption rate of 0% or less and a dielectric constant of 3% or less. No deterioration of the layer is observed and it shows very good heat resistance. Since this intermediate layer exhibits excellent adhesiveness by thermocompression bonding at a relatively low temperature for a short time, a flexible copper clad laminate can be obtained very easily. Further, since the water absorption of the intermediate layer is low, the intermediate layer does not absorb moisture during storage, and there is no need to perform the step of forming the adhesive layer during the production of FPC or the like as in the conventional case, and the present invention can be used in advance. It is possible to prepare the above flexible copper clad laminate. Thereby, the production of the FPC can be further simplified. Further, in the FPC and the like produced by this flexible copper-clad laminate, since the intermediate layer has a low dielectric constant, the delay of electric signals is reduced, and it is possible to provide the FPC and the like having excellent electric characteristics.

The embodiments of the flexible copper clad laminate according to the present invention have been described above. However, the present invention is not limited to these, and the present invention will be understood by those skilled in the art within the scope of the invention. Based on the above, various improvements, changes and modifications can be implemented.

[0068]

EXAMPLES First, among the diamine compounds represented by the general formula (4) used in the examples of the present invention, bis (2-
(4-aminophenoxy) ethoxy) ethane (hereinafter DA
It is called 3EG. The adjustment method of () will be described and used as a reference for the examples.

[Synthesis of p-Nitrophenol Na Salt] In a separable flask of 1 liter capacity equipped with a mechanical stirrer, 192.99 g (1.39 mol) of p was added.
An aqueous solution was prepared by dissolving nitrophenol and 55.5 g (1.39 mol) of sodium hydroxide in 500 ml of water. After reacting at 100 ° C. for 4 hours, the temperature was returned to room temperature, and the reaction solution was allowed to stand overnight as it was. Crystals began to precipitate, so crystals were collected on a filter bed. When the crystal was washed with toluene to remove water and dried, 165.
57 g (yield; 74.0%) of Na salt was obtained. Melting point is 1
It was 13.4 ° C (reference value; 113 ° C).

[Synthesis of Bis (2- (4-nitrophenoxy) ethoxy) ethane] In a 1-liter separable flask equipped with a dropping funnel and a mechanical stirrer,
4.5 g (0.46 mol) of p-nitrophenol Na
The salt and 250 ml of DMF were charged and the reaction system was brought to 140 ° C. After the Na salt is completely dissolved, 43 g from the dropping funnel
(0.23 mol) 1,2-bis (2-chloroethoxy) ethane was slowly added dropwise. After continuing the reaction overnight, the reaction solution was poured into a large amount of water to obtain a precipitate. The precipitate was collected by suction filtration and recrystallized with toluene as a solvent. As a result, 59.14 g (yield: 65.6%) of a dinitro compound; bis (2- (4-nitrophenoxy) ethoxy) was obtained. I got ethane. The melting point was 96.2 ° C (literature value; 96 ° C).

[Synthesis of Bis (2- (4-aminophenoxy) ethoxy) ethane (DA3EG)] A Dimroth reflux condenser, a dropping funnel and a mechanical stirrer were attached 1.
26.26 g in a liter separable flask
(0.067 mol) bis (2- (4-nitrophenoxy) ethoxy) ethane, 500 ml ethanol, 3 g 1
0% palladium on activated carbon was charged. After the reflux was started, 16 g (0.135 mol) of hydrazine monohydrate was slowly added dropwise using a dropping funnel. After refluxing overnight, palladium on activated carbon was filtered off under reduced pressure using a celite bed. When the solvent was distilled off under reduced pressure, a solid crude product was obtained. When recrystallization operation was performed using ethanol as a solvent, 10.07 g (yield; 45.3%) of diamine; DA3EG was obtained. Melting point is 95.0 ° C
(Reference value; 92.7 ° C.).

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0073]

[Example 1] A 500 ml three-necked flask equipped with a stirrer and purged with nitrogen was charged with 20.02 g (0.10 mol) of oxydianiline represented by the general formula (3) (hereinafter referred to as ODA) and the above method. D represented by the general formula (4)
A3EG16.6g (0.050mol) and dimethylformamide (henceforth DMF) 250g were prepared. In it, 61.55 g (0.15 mol) of 3,3 ′, 4,4′-ethylene glycol dibenzoate tetracarboxylic dianhydride (hereinafter referred to as EGDA) represented by the general formula (5),
Add up to 60 g of powder, and pay attention to the viscosity in the three-necked flask measured by a B-type viscometer.
A solution prepared by dissolving 5 g of DMF in 30 g was gradually put into a three-necked flask. When the maximum viscosity is reached, EG
After the addition of the DA solution was completed, the solution was left stirring for 1 hour. Then, 40 g of DMF was added and stirred to obtain a polyamic acid solution in which the molar ratio of the general formula (1) and the general formula (2) was 3: 2. The structure of the obtained polyamic acid solution is such that the R ₁ group is —CH ₂ —CH ₂ —R ₂ group

[0074]

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The R ₃ group was a hydrogen group, n was 3, and the substitution site was the para position. The ultimate viscosity was 2500 poise. The viscosity was measured at 5 ° C.

This polyamic acid solution was applied onto a PET film, heated at 80 ° C. for 25 minutes, and then peeled off from the PET film to fix the ends to a metal support. And
It was heated at 150 ° C., 250 ° C., 270 ° C., and 300 ° C. for 5 minutes each to obtain a 25 μm thick thermoplastic polyimide film of the above structure used as an intermediate layer in the present invention.

Next, a 35 μm thick electrolytic copper foil, the 25 μm thick thermoplastic polyimide film obtained above, and another 25 μm thick polyimide film “Apical 25 NPI”.
(Registered trademark), manufactured by Kanegafuchi Chemical Industry Co., Ltd., and pressed at 250 ° C. and 30 kgf / cm ² for 10 minutes to form a flexible copper-clad laminate of the present invention (hereinafter referred to as FCCL).
I got

The glass transition temperature (° C.) of the obtained thermoplastic polyimide film was measured by TMA, and it was 150 ° C. Also, ASTM D-570
Based on the standard, the weight change rate when immersed in pure water at 20 ° C. for 24 hours was measured, and the water absorption rate (%) was examined.
%Met. Further, the dielectric constant (−) was 2.95 as measured by the Q meter method (state, 1 MHz) according to JIS C6481. Also, the obtained FCCL
Peel strength according to JIS C6481 (kgf
/ Cm) was 1.1 kgf / cm. Further, when the obtained FCCL was subjected to a radiation resistance test by irradiation with 5 MGy using an electron beam of 2 MeV, the FCCL did not show discoloration or change in performance. Table 1 shows the results.

[0079]

[Table 1]

[0080]

Example 2 DA3EG represented by the general formula (4),
From 2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ', 4,4'-tetracarboxylic dianhydride (hereinafter referred to as ESDA) represented by the general formula (5), By the same method as in Example 1, a polyamic acid solution represented by General Formula (2) alone was obtained. Then, using this polyamic acid solution, a thermoplastic polyimide film having a thickness of 25 μm was obtained in the same manner as in Example 1, and further the intended FCCL was obtained.

The properties of the obtained thermoplastic polyimide film and FCCL were measured in the same manner as in Example 1. The glass transition temperature of the thermoplastic polyimide film was 132 ° C., the water absorption rate was 0.7%, and the dielectric constant was Is 2.94
Met. The peel strength of the obtained FCCL is 1.
It was 0 kgf / cm, and the FCCL did not undergo discoloration or change in performance due to the radiation resistance test. These results are shown in Table 1.
Shown in

[0082]

Example 3 From the ODA represented by the general formula (3) and the ESDA represented by the general formula (5), the compound represented by the general formula (1) alone was prepared in substantially the same manner as in Example 1. A polyamic acid solution was obtained. And using this polyamic acid solution,
A thermoplastic polyimide film having a thickness of 25 μm was obtained in the same manner as in Example 1, and further the intended FCCL was obtained.

The properties of the obtained thermoplastic polyimide film and FCCL were measured in the same manner as in Example 1. The glass transition temperature of the thermoplastic polyimide film was 180 ° C., the water absorption rate was 0.8%, and the dielectric constant was Is 2.95
Met. The peel strength of the obtained FCCL is 1.
It was 0 kgf / cm, and the FCCL did not undergo discoloration or change in performance due to the radiation resistance test. These results are shown in Table 1.
Shown in

[0084]

[Comparative Example 1] From pyromellitic dianhydride and ODA,
A polyamic acid solution was obtained in substantially the same manner as in Example 1, and further a thermoplastic polyimide film having a thickness of 25 μm was obtained. Then, when an FCCL was produced in the same manner as in Example 1, no fusion was caused and FCCL could not be obtained.

The glass transition temperature (° C.), water absorption rate (%) and dielectric constant (−) of the thermoplastic polyimide film obtained in the same manner as in Example 1 were measured. The index was 2.6% and the dielectric constant was 3.50. Table 1 shows the results.

[0086]

Comparative Example 2 A polyamic acid solution was obtained from pyromellitic dianhydride and paraphenylenediamine in substantially the same manner as in Example 1, and a thermoplastic polyimide film having a thickness of 25 μm was obtained. Then, in the same manner as in Example 1, FC
When an attempt was made to produce CL, it was not fused and FCCL could not be obtained.

The glass transition temperature (° C.), water absorption rate (%) and dielectric constant (−) of the thermoplastic polyimide film obtained in the same manner as in Example 1 were measured. The dielectric constant was 3.2% and the dielectric constant was 3.40. Table 1 shows the results.

[0088]

Comparative Example 3 Instead of the thermoplastic polyimide film as the intermediate layer, an epoxy adhesive composed of “Epicoat 828 (trade name; manufactured by Yuka Shell Co., Ltd.)” was used, and Example 1 was used.
FCCL was obtained in the same manner as. The peel strength of the obtained FCCL was measured in the same manner as in Example 1,
It was 0.3 kgf / cm. Also, the radiation resistance test caused the FCCL intermediate layer to turn black. In addition, Example 1
The glass transition temperature (° C.), water absorption rate (%), and dielectric constant (−) of “Epicoat 828 (trademark)” were measured in the same manner as in 1. and the glass transition temperature was 178 ° C. and the water absorption rate was 1.98.
%, The dielectric constant was 3.8. Table 1 shows the results.

[0089]

As described above, the flexible copper clad laminate of the present invention comprises a base film layer made of a heat resistant resin,
Glass transition temperature is 100 ° C to 250 ° C, and further 1
% Or less and a dielectric constant of 3 or less, and an intermediate layer made of a thermoplastic resin, and a conductor layer made of a good electrical conductor. A polyimide resin having a specific structure composed of both or at least one of the block units represented by 1) and the general formula (2) is preferably used.

Specifically, since the flexible copper-clad laminate of the present invention uses a polyimide resin as the intermediate layer, it exhibits excellent heat resistance and no deterioration of the intermediate layer is observed even at high temperatures. Is retained. Moreover, this polyimide resin has a low glass transition temperature of 100 to 250 ° C. and exhibits excellent adhesiveness when laminated at a temperature near or higher than the glass transition temperature, and thermocompression bonding at a relatively low temperature and a short time. Shows excellent adhesiveness. Therefore,
A flexible copper-clad laminate in which the base film layer and the conductor layer are firmly adhered can be very easily obtained, and the processing time thereof can be shortened. Furthermore, this polyimide resin exhibits a low water absorption rate of 0.1% or less, and the intermediate layer does not absorb moisture during storage, and it can be supplied as a flexible copper-clad laminate, which is the same as conventional FPC. It becomes unnecessary to perform the process from the step of forming the adhesive layer at the time of manufacturing the above. Further, also in the FPC manufacturing process, it is possible to provide a high quality product without the intermediate layer absorbing moisture as in the conventional case. Moreover, since the dielectric constant is as low as 3 or less,
As a result, the delay of the electric signal in the obtained FPC is alleviated, and the FPC having excellent electric characteristics can be manufactured.

In addition, this polyimide resin also has excellent properties such as low dielectric properties and radiation resistance. According to the present invention, mechanical strength, heat resistance, radiation resistance, workability and adhesiveness are improved. It is possible to obtain a flexible copper-clad laminate having excellent heat resistance, low water absorption and excellent dielectric properties. Due to these excellent characteristics, the flexible copper clad laminate of the present invention is suitable for use as a high density packaging material such as LOC package and MCM, a printed wiring board material such as multilayer FPC, and further as an aerospace material.

By forming the wiring pattern by etching the copper clad laminate obtained by forming the intermediate layer with a polyimide resin, the base film layer and intermediate layer made of polyimide are further etched by alkali etching. The layers can be perforated and a double sided FPC can be made relatively easily. Similarly, it can be preferably used as a multilayer FPC material, and is also suitable for other uses such as a rigid flex substrate material.

Claims (4)

[Claims] 1. A base film layer made of a heat resistant resin, and an intermediate layer made of a thermoplastic resin having a glass transition temperature of 100 ° C. to 250 ° C. and further having a water absorption rate of 1% or less and a dielectric constant of 3 or less. And a conductor layer made of a good electrical conductor, which is a flexible copper-clad laminate. 2. The thermoplastic resin is represented by the general formula (1): And the general formula (2) (In the formula, R ₁ and R ₂ are divalent organic groups, R ₃ is an organic group selected from hydrogen, a methyl group, and a phenyl group, n is an integer of 1 to 4, and X is Chemical formula 3 It is a trivalent linking group selected from ) The flexible copper-clad laminate according to claim 1, comprising both or at least one of the block units represented by (1). 3. R ₁ in the general formulas (1) and (2) is represented by the following formula: It is at least 1 sort (s) selected from the group of the bivalent organic group shown in Claim 3, The flexible copper clad laminated board of Claim 2 characterized by the above-mentioned. 4. R ₂ in the general formula (1) is represented by the following formula: It is at least 1 sort (s) selected from the group of the bivalent organic group shown in Claim 4, The flexible copper clad laminated board of Claim 2 or Claim 3 characterized by the above-mentioned.