KR20070092778A - Thermoplastic polyimide film and its usage - Google Patents

Abstract

A thermoplastic polyimide film is provided to improve adhesive strength between polyimide film and metal even after exposure under a high-temperature and high-humidity environment. A thermoplastic polyimide film is formed of polyimide. The polyimide has a molecular weight of 5,000-10,000,000 and comprises 0.25-90.25mol% of a repeat unit represented by the following formula 1, 0.25-90.25mol% of a repeat unit represented by the following formula 2, 0.25-90.25mol% of a repeat unit represented by the following formula 3, and 0.25-90.25mol% of a repeat unit represented by the following formula 4. In the formulae, l, m, n, and o are a positive integer of 1 or greater.

Description

Thermoplastic polyimide film and its use {Thermoplastic polyimide film and its usage}

The present invention relates to a thermoplastic polyimide film and its use, and more particularly, a thermoplastic polyimide film formed in a film form from a polyamic acid obtained from two diamines and two dianhydrides, and a two layer comprising the same. A metal laminate, a polyimide laminate, and a multilayer flexible printed wiring board.

Since the polyimide film has heat resistance, insulation, solvent resistance and low temperature resistance, for example, an FPC (Flexible Printed Wiring Board) or TAP (which is an insulating support for a computer or IC control electric / electronic device component material) Tape Automated Bonding) Widely used as a base film for tape. Miniaturization and high functionalization of electric devices are progressing, and miniaturization and weight reduction of the electronic components used with them are also required. As a technology for mounting electronic components, a chip on FPC (COF) or a tape carrier package (TCP) technology has been established, and is already used, for example, for packaging an LCD or a PDP display device driving element.

As the above-mentioned mounting technology, further high-definition of wiring and high-density of electronic component mounting are progressing. In order to cope with this high-definition and high-density, the use of the board | substrate with which a metal layer is laminated | stacked directly, without passing through an adhesive agent with respect to a polyimide film, what is called a 2-layer type board | substrate is examined as a board | substrate used for each of COF and TCP. Since the substrate of the two-layer type can cope with thinning of the metal layer, it can cope with high density of wiring.

That is, in a conventional three-layer type substrate in which an adhesive layer is interposed between a polyimide film and a metal layer, when a bias is applied under high temperature and high pressure, a short circuit between wirings occurs due to the movement of metal ions in the adhesive layer. There was a limit to the densification. On the other hand, since the two-layer type substrate does not have an adhesive layer, it has become popular as a technique capable of covering the drawbacks of the conventional three-layer type substrate. For this reason, the two-layer type substrate is not only used in the above-described component mounting technology because of this advantage, but also applied to, for example, HDD wireless suspension or cartridges for inkjet printers.

However, the two-layer type substrate had the drawback that the metal layer deposited directly on the polyimide film easily peeled off the polyimide film. That is, the adhesion between the polyimide film-metal of the two layer type substrate is inferior to that of the three layer type substrate. Accordingly, various techniques have been proposed in order to improve the adhesion strength between polyimide film and metal.

For example, Japanese Patent Laid-Open No. 5-295142, Japanese Patent Laid-Open No. 9-36539, Japanese Patent Laid-Open No. 10-204646, and the like describe a method of wet-modifying the surface of a polyimide film with an alkaline solution. It is. Japanese Patent Laid-Open No. 11-117060 discloses a method of modifying the surface of a polyimide film by plasma treatment, and Japanese Patent Laid-Open No. 6-124978 or the like discloses a polyimide or the like on the surface of a polyimide film. Japanese Patent Laid-Open No. 2001-277424 discloses a method of applying the polyamic acid as a precursor thereof and a method of roughening the surface of the polyimide film for use. Each of the above techniques requires not only an improvement step of modifying the surface of the polyimide film as a post-treatment, but also a problem that an residue of organic matter may remain on the surface of the polyimide film by this improvement step. have. Moreover, there exists also a problem that adhesive strength between sufficient polyimide film-metals is not obtained even through the said improvement process.

On the other hand, there is also disclosed a technique for improving the adhesion strength between the polyimide film and the metal by improving the adhesiveness of the polyimide film itself without requiring the above improvement process in the post-treatment. The technique of Unexamined-Japanese-Patent No. 06-073209, Unexamined-Japanese-Patent No. 08-330728, etc. are mentioned. Here, the adhesiveness of the polyimide film in a state is aimed at by using the polyimide film containing the organic tin compound. However, in each of the above publications, there is a problem that the organic tin compound is converted into a harmful tin compound when the organic tin compound is used or in the process of forming the polyimide film.

Moreover, as a technique of Unexamined-Japanese-Patent No. 1948445, the adhesiveness of the polyimide film in a state is proposed by using the polyimide film containing a titanium type organic compound. However, the inclusion of a titanium-based organic compound causes a problem that the color of the polyimide film is significantly thickened and embrittled. In addition, Japanese Patent Application Laid-Open No. 2000-326442 discloses a method of treating the surface of a film-form formed body (gel film) before becoming a polyimide film with an organic titanium-based solution to improve the adhesiveness of the polyimide film itself. Is being proposed.

By applying the method described in each of the above publications for improving the adhesion of the polyimide film itself as described above, it is possible to improve the adhesion strength between the polyimide film and the metal in the state. On the other hand, the two-layer film should be considered to be exposed under prolonged heat load conditions or high temperature and high humidity environment. Therefore, it is desired to be excellent also in the adhesive strength between the polyimide film and the metal after a long term heat load or after exposure in a high temperature, high humidity environment.

By the way, as a manufacturing method of a polyimide film, in the step of the gel film formed by casting the organic solvent solution of the polyamic acid which is a precursor of a polyimide to a support body, and partially hardening and / or drying until it has self-support, The process for modifying the surface of a mid film may be performed.

For example, Japanese Patent Laid-Open No. 48-7067 describes a method of coating a polyamic acid on a gel film. In addition, Japanese Patent Laid-Open No. 10-58628 discloses a multilayer polyimide film coated with a polyamic acid solution on a gel film and having an amorphous polyimide on its surface. In addition, Japanese Patent Application Laid-Open No. 2000-43211 discloses providing a polyimide film having good adhesion by applying a polyamic acid solution to a gel film.

However, as the technique described in each publication described above, there is a problem in the dimensional stability of the polyimide film because the dimensional change and the water absorption rate due to moisture absorption are not sufficiently low. In addition, each publication mentioned above does not describe at all the improvement of the adhesive strength between polyimide film and metal as a 2-layer type board | substrate with which a metal layer is directly laminated | stacked without an adhesive with respect to a polyimide film. In addition, in view of the expansion of the process of mounting components on two-layer boards and the use of equipment using two-layer boards, after a long period of heat load or after exposure in a high temperature, high humidity environment, Although the reliability of the adhesion strength between the polyimide film and the metal is expected to be improved, each of the above documents does not describe the improvement of the reliability.

In addition, the two-layer type substrate is used to increase the density of wiring or mounting components, to use the two-layer type substrate in harsh environments, and to use the two-layer type substrate for patterning of wiring and component mounting. In view of the severe processing conditions leading to the above, high dimensional stability is required for the polyimide film used for the two-layer type substrate. In order to satisfy the requirement of this high dimensional stability, the polyimide film has: (1) a linear expansion coefficient having a sufficiently low level equivalent to that of the metal layer in the two-layer type substrate; (2) a small change in the dimensional stress. In addition to the properties (dimension stability) for heat and stress described in ① and ②, it is important that the dimensional change due to moisture absorption is low and the water absorption of the polyimide film itself is low.

In order to obtain the various properties described in the above ① to ④, for example, Japanese Patent Laid-Open No. 2001-72781 discloses, as a raw material monomer, p-phenylenebis (trimelitic acid monoester acid anhydride) similar to an acid anhydride. I use water. The use of this acid anhydride and the like gives the polyimide film excellent in dimensional stability by obtaining various properties described in the above ① to ④, but for the two-layer type substrate, as described above, the polyimide film-metal Strong adhesion is required. In particular, it is preferable that the adhesion is sufficiently maintained even after the high-temperature environment exposure, which is the use environment or processing conditions of the two-layer type substrate.

On the other hand, briefly look at the manufacturing process of the FPC, first to produce a flexible copper foil laminate by bonding a copper film and a polyimide film as a base film, and to form a resist pattern on the conductor by screen printing or photoresist method and etching To form a circuit pattern. Thereafter, the cover film is bonded onto the circuit surface of the film on which the circuit pattern is formed. In such a step, acrylic adhesives and epoxy adhesives are mainly used as adhesives for bonding the base film and the copper foil or for the cabarets for bonding the cover film to the circuit surface. However, these adhesives were inferior in heat resistance and high in water absorption.

For this reason, the characteristics, such as heat resistance and dimensional stability of the obtained FPC, depend on the characteristic of an adhesive agent, and there exists a problem that many polyimide films used as a cover film and a base film cannot exhibit the outstanding characteristic. In addition, as the multilayering of FPC has progressed recently, the demand for double-sided adhesive sheets having adhesives attached to both sides of the base film is increasing. However, since the adhesives are also used in such double-sided adhesive sheets, the excellent properties of the polyimide film cannot be sufficiently exhibited. The same is true.

In the FPC manufacturing process, as a method of adhering the cabaret film to the circuit surface, the cabarray film with the adhesive is processed into a predetermined shape or the like on one surface obtained by adhering the adhesive to the surface of the polyimide film, and the circuit pattern is formed. The method of laminating | stacking on the circuit surface of a film, making a position, and thermocompression bonding with a press etc. is common. In such a method, when the adhesive is used, a perforation process cannot be performed after adhering the cabaret film to the FPC. Therefore, in the cabaret film, holes or windows are formed in the terminal part of the circuit formed on the conductor or the connection part with the component before the film is adhered. It was necessary to process such as drilling.

However, it is not only difficult to drill holes in the thin cabaret film, but also the alignment for fitting the cabaret film with holes or the like to a predetermined position of the FPC is usually close to manual work, poor in workability and increased in cost. In addition, in the case where the thickness of the adhesive layer of the cabaret film is thin, voids may be generated between the FPC and the cabaret film. On the other hand, when the thickness of the adhesive layer is thick, the adhesive is pulled out of a hole or the like. There existed a problem, such as poor conduction.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is a polyimide / metal laminate, which is a two-layer type substrate, in addition to the adhesion strength between polyimide film-metal in ordinary conditions, in high temperature and high humidity environments. It is an object of the present invention to provide a thermoplastic polyimide film capable of improving the adhesive strength between polyimide film and metal even after the exposure.

In addition, an object of the present invention is to provide a suitable thermoplastic polyimide film which is excellent in adhesiveness in producing a flexible printed wiring board and which can be used as an adhesive layer for a cabaret or an adhesive layer for FCCL or a double-sided adhesive sheet.

It is also an object of the present invention to provide a two-layer metal laminate comprising such a thermoplastic polyimide film.

Another object of the present invention is to provide a polyimide laminate in which such a thermoplastic polyimide film is laminated on a polyimide base film.

Another object of the present invention is to provide a multilayer flexible printed wiring board (FPC) comprising a thermoplastic polyimide film as a bonding sheet.

Thermoplastic polyimide film for achieving the above object is 0.25 ~ 90.25 mol% repeating units represented by the following formula (1), 0.25 ~ 90.25 mol% repeating units represented by the following formula (2), 0.25 repeating units represented by the following formula (3) It is characterized by consisting of polyimide having a molecular weight of 5,000 to 10,000,000, including ~ 90.25 mol% and 0.25 ~ 90.25 mol% repeating units represented by the following formula (4).

Formula 1

Formula 2

Formula 3

Formula 4

In Formulas 1 to 4, l, m, n, and o are positive integers of 1 or more.

The film thus obtained has a glass transition temperature of 150 to 300 ° C and a thermal expansion coefficient of 10 to 100 ppm / ° C.

In addition, the moisture content by the change in weight satisfies the characteristic of less than 2%.

The present invention is characterized by a two-layer metal laminate composed of the thermoplastic polyimide film and the metal layer as described above.

Such metal laminates were exposed to an environment of 121 ° C. and 100% RH for 96 hours after measuring the adhesion strength between the 1 mm wide wiring pattern and the polyimide film obtained by etching the metal layer. It is characterized by maintaining at least 50% of the adhesive strength before exposing to.

On the other hand, the present invention is also characterized in that the polyimide laminate laminated on the polyimide base film, wherein the thermoplastic polyimide film is laminated with the polyimide base film and heated by pressing at 100 to 1,000kgf at a pressure of 150 to 350 ℃ When the adhesive force is characterized by satisfying more than 0.5kgf / cm.

In addition, the multilayer flexible printed wiring board of the present invention is characterized in that it is bonded using the thermoplastic polyimide film as a bonding sheet.

The present invention will be described in more detail as follows.

The present invention relates to a thermoplastic polyimide film having excellent adhesion, low moisture content and excellent adhesion at high temperatures.

The thermoplastic polyimide film of the present invention has a structure in which the linear irregularly arranged structure includes a repeating unit represented by Formula 1, a repeating unit represented by Formula 2, a repeating unit represented by Formula 3, and a repeating unit represented by Formula 4. As having, such a thermoplastic polyimide film is obtained by polymerizing diamine and dianhydride to produce a polyamic acid, which is molded into a film.

The preparation of the thermoplastic polyimide copolymer constituting the thermoplastic polyimide film of the present invention comprises two kinds of diamines, 1,3-bis (4-aminophenoxy) benzene (hereinafter referred to as TPER) and 2,2-bis [4- (4-aminophenoxyphenyl) propane] (hereinafter referred to as BAPP) is used. Specifically, TPER is used as χ mol% in the total diamine content, and BAPP is used as (100-χ) mol% (where χ is 5.0 ≦ χ ≦ 95.0).

The dianhydrides include 2,2-bis [4- (4-dicarboxyphenoxyphenyl) propane] (hereinafter referred to as BSAA) and 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride Water (hereinafter referred to as BTDA) is used. Specifically, BSAA is used as ξmole% in the total dianhydride content, and BTDA is used as (100-ξ) mole% (wherein ξ is 5.0 ≦ ξ ≦ 95.0).

The polymerization of the polyamic acid using such two diamines and two dianhydrides is carried out according to the conventional polymerization method of polyamic acid, and the polymerization temperature is preferably 0 ° C. to 90 ° C., and the solid content is total. It is desirable to maintain 5% to 50% relative to the composition.

Since the molar ratio of dianhydride and aromatic diamine affects the molecular weight, and the molecular weight greatly affects the film properties, it is necessary to precisely control the equivalents.

According to the present invention, the molar ratio of dianhydride and aromatic diamine is preferably 0.95: 1 to 1: 0.95, and the logarithmic viscosity is preferably 0.3 to 2.0 dl / g.

As the organic solvent used to prepare the polyamic acid copolymer, it is preferable to use a solvent having a polarity such as ether and ketone. Specific examples include N-methyl-2-pyrrolidone (hereinafter referred to as NMP), N, N'-dimethylacetamide (hereinafter referred to as DMAc), and N, N'-dimethylformamide (hereinafter referred to as DMF. ), Dimethyl sulfoxide (hereinafter referred to as DMSO) can be used alone or in combination of one or more selected.

As a method for producing a polyimide film from the polymerized polyamic acid polymer as described above, the method is generally divided according to a method of performing imidization, and includes a thermal method for dehydration by heating; There is also a chemical method using a dehydrating agent or an imidization catalyst. Any of these methods may be used, or both chemical and thermal methods may be used in combination. By the way, according to the chemical method which adds a dehydrating agent and a catalyst, and heats and drys, the characteristic which is more efficient and excellent than a thermal method can be provided to a film. Even when a dehydrating agent or an imidization catalyst is not used, the monomers of the present invention can be used to achieve the same characteristics by a drawing process, for example, but a chemical method is preferable in terms of productivity. .

Such dehydrating agents include aliphatic acid anhydrides such as acetic anhydride, aromatic acid anhydrides, and the like. As a catalyst used for imidation, tertiary amines, such as pyridine, (alpha)-picoline, (beta)-picoline, trimethylamine, dimethylaniline, triethylamine, isoquinone, etc. are mentioned.

In the following Examples, although the chemical method of imidation is given, this invention is not limited to this.

Looking at one example of the preparation of a polyimide film using a specific chemical method of imidization, the prepared polyamic acid solution is reacted with a dehydrating agent to form a gel film having at least a portion of the polyamic acid having polyisoimide (partially imidized). It is a method of forming and heat-treating the obtained gel film in a tenter. Normally, polyimisoimide, that is, the state which is partially imidized, can be evaluated by the imidation ratio calculated by the following formula 1 using infrared absorption spectroscopy, which is known in the art. Specifically, the "partially imidated state" means that the imidation ratio calculated by the following formula 1 is 50% or more, preferably 70% or more, more preferably 80% or more, even more preferably 85%. Or more preferably 90% or more.

Equation 1

(A / B) / (C / D) × 100

Wherein, A is the height of the absorption peak of the gel film of 1370cm ^-1, B is the height of an absorption peak in the gel film 1500cm ^-1, C is the height of an absorption peak at 1370cm ^-1 of the polyimide film, D Represents the height of the absorption peak at 1500 cm ⁻¹ of the polyimide film.

Thus obtained polyimide film is 0.25 ~ 90.25 mol% of repeating units represented by Formula 1, 0.25 ~ 90.25 mol% of repeating units represented by Formula 2, 0.25 ~ 90.25 mol% of repeating units represented by Formula 3 and Formula 4 It comprises a polyimide having a molecular weight of 5,000 to 10,000,000 irregularly arranged linearly, including 0.25 to 90.25 mol% of the repeating units indicated.

Such polyimide film is not limited in terms of thickness but is preferably in the range of 10 to 300 µm, preferably in the range of 12 to 225 µm.

The thermoplastic polyimide film of the present invention obtained as described above has a low moisture content and excellent adhesion.

Specifically, the thermoplastic polyimide film of the present invention has a glass transition temperature of 150 to 300 ° C., a thermal expansion coefficient of 10 to 100 ppm / ° C., and a moisture content of 2% or less due to weight change.

In addition, the two-layer metal laminated body obtained from the thermoplastic polyimide film of this invention is demonstrated.

In the two-layer metal laminate of the present invention, a metal layer is laminated on one or both surfaces of the thermoplastic polyimide film obtained by the above-described method. The polyimide film / metal laminate can be produced by any method well known in the art, but for example, the obtained thermoplastic polyimide film can be prepared by vacuum deposition, sputtering, ion plating, plating, or the like. Can be stacked directly. In this case, the metal layer may be one kind of metal, but two or more kinds of metals may be stacked one by one, or two or more kinds of metals may be mixed and stacked as an alloy.

In the case of using one kind of metal, the kind of metal is not particularly limited, but copper is particularly preferable.

In such a polyimide / metal laminate, in the 1 mm wide wiring pattern formed by etching a metal layer, the adhesive strength after environmental exposure at 121 ° C., 100% RH, and 96 hours is 50% or more of the adhesive strength before the environmental exposure. I can keep it. In other words, the adhesion with the metal is excellent even under severe conditions.

In addition, the thermoplastic polyimide film of the present invention may generally be used in place of the adhesive layer that has been used for adhesion between the base film and the metal. As described above, since the thermoplastic polyimide polymer of the present invention has a clear glass transition point between 150 and 300 ° C., the polyimide film and the copper foil, or the polyimide film may be separated by laminating at a temperature close to the glass transition point. It can adhere easily, and shows favorable low temperature adhesiveness. Specifically, the thermoplastic polyimide film of the present invention has a property that the adhesive strength at the pressure of 100 to 1,000 kgf at 150 to 350 ° C. after lamination with the polyimide substrate film satisfies 0.5 kgf / cm or more.

Therefore, the thermoplastic polyimide film of the present invention can be suitably used as an adhesive layer of a flexible copper foil laminate (FCCL), a double-sided adhesive sheet, or a cover film, replacing a conventional acrylic or epoxy adhesive.

In addition, since the thermoplastic polyimide film of the present invention exhibits low water absorption, it can be suitably used not only as an adhesive film but also as a base film or a cover film of FCCL.

The polyimide laminate obtained by laminating the thermoplastic polyimide film of the present invention on both sides or one side of the non-thermoplastic polyimide film can be used as a double-sided or one-sided polyimide adhesive sheet using such a thermoplastic polyimide film as an adhesive layer. It can also be used as FCCL by adhering to copper foil etc.

The method of manufacturing a polyimide laminated body can be produced simply by laminating the thermoplastic polyimide polymer film of this invention on both surfaces or one surface of a base film like a polyimide film, and then heat-compressing.

 On the other hand, the thermoplastic polyimide film of the present invention is generally useful as a bonding sheet of a multilayer flexible printed wiring board.

In the following, examples of the thermoplastic polyimic acid polymer according to the present invention, a manufacturing method thereof, and a film and a laminate using the same are described. However, the present invention is not limited only to the examples.

The abbreviation used in each example is as follows.

TPER: 1,3-bis (4-aminophenoxy) benzene

BAPP: 2,2-bis [4- (4-aminophenoxy phenyl) propane]

BAPP: 2,2-bis [4- (4-dicarboxyphenoxy phenyl) propane]

BTDA: 3,4,3`, 4`-benzophenone tetracarboxylic dianhydride

m-PDA: m-phenylene diamine

Synthesis Examples 1 to 18

The polyamic acid was synthesized according to a conventional method using TPER, BAPP and m-PDA as diamines, and BTDA and BSAA as dianhydrides in compositions and contents as shown in Table 1 below.

Specifically, a 500 ml 4-necked round flask was equipped with a thermometer, a calcium chloride tube connected with a nitrogen inlet, and a mechanical stirring rod. The total diamines and dianhydrides were made into a 1: 1 molar ratio, DMAc was added in a nitrogen atmosphere, and a certain amount of BAPP and TPER was added thereto, followed by stirring for 10 minutes to dissolve well. Quantitative amounts of BSAA and BTDA were dissolved in DMAc and then slowly added dropwise to the mixture at room temperature. The mixed reaction solution was stirred for 6 hours, and then heated to 60 ° C. for 6 hours to obtain a polyamic acid. The composition of each component is shown in Table 1, and the content shows mol%.

The obtained polyamic acid was confirmed through elemental analysis as shown in Table 2 below. In addition, the intrinsic viscosity and molecular weight were measured, and the results are shown in Table 2 below.

Intrinsic viscosity was measured using a Cannon-Ubbelohde Viscometer according to ASTM D795-26. Elemental analysis was performed using AA-680, SHIMADZU Inc. The glass transition temperature (Tg) was measured by DSC (Perkin Elmer Inst. P-7) according to ASTM E1356-03, and the weight average molecular weight (Mw) was ASTM D 6474-99. According to the measurement, using GPC (Waters 150-CV).

Synthesis Example Diamines (100 mol%) Dianhydride (100 mol%) BAPP TPER m-PDA BSAA BTDA 1 2 3 4 5 6 20 20 20--100 80 80 80-100- ---100-- 20 50 80 20 20 20 80 50 20 80 80 80 7 8 9 10 11 12 50 50 50--100 50 50 50-100- ---100-- 20 50 80 50 50 50 80 50 20 50 50 50 13 14 15 16 17 18 80 80 80--100 20 20 20-100- ---100-- 20 50 80 80 80 80 80 50 20 20 20 20

Synthesis Example Elemental Analysis (%) Properties C H N O IV Tg (℃) Mw (g / mole) One 69.99 3.99 4.51 21.52 1.30 241 677,870 2 71.21 4.28 4.51 20.00 1.00 230 737,360 3 72.44 4.58 4.51 18.47 0.80 226 796,840 4 65.82 4.87 12.95 16.36 1.10 221 470,030 5 69.48 3.90 4.79 21.84 0.70 181 654,230 6 72.00 8.66 3.41 20.26 0.15 209 772,440 7 71.77 2.72 4.16 21.35 1.10 226 713,330 8 71.97 4.41 4.10 19.52 0.90 213 772,820 9 73.19 4.71 4.10 18.00 1.00 209 832,310 10 67.05 5.17 12.95 14.84 0.90 235 529,520 11 70.70 4.20 4.79 20.31 0.86 228 713,720 12 73.23 4.63 3.41 18.73 0.98 222 831,930 13 68.43 4.06 3.53 23.98 1.30 230 748,800 14 69.61 4.35 3.53 22.52 0.80 226 808,280 15 70.78 4.63 3.53 21.06 1.00 213 867,770 16 71.93 4.50 4.79 18.79 0.90 198 773,200 17 68.27 5.47 12.95 13.31 1.20 189 589,000 18 74.46 4.93 3.41 17.21 1.02 213 891,410

From the results in Table 2, the polyimide copolymer constituting the polyimide film of the present invention can be seen that the glass transition temperature satisfies the range of 150 to 300 ℃, thereby easy thermal bonding at low temperatures.

<Examples 1-3>

To each of the polyamic acid solutions obtained in Synthesis Examples 1 to 3, pyridine was added in an amount greater than stoichiometric as a dehydrating agent, stirred uniformly, fired on a SUS plate, and cast to a predetermined thickness. Hot air dried at 10 to 30 minutes. Thereafter, the film was pulled off from the SUS plate and heat-dried at 250 ° C. to 400 ° C. for 10 to 60 minutes while fixing the four sides, thereby obtaining a thermoplastic polyimide film having a thickness of 25 μm.

<Examples 4 to 6>

A thermoplastic polyimide film was obtained in the same manner as in Example 1 from the respective polyamic acid solutions obtained in Synthesis Examples 7 to 9.

<Examples 7-9>

A thermoplastic polyimide film was obtained in the same manner as in Example 1 from the respective polyamic acid solutions obtained in Synthesis Examples 13 to 15 above.

<Comparative Examples 1 to 3>

The thermoplastic polyimide film was obtained by the same method as Example 1 from the respective polyamic acid solutions obtained in Synthesis Examples 4 to 6.

<Comparative Examples 4 to 6>

A thermoplastic polyimide film was obtained in the same manner as in Example 1 from the respective polyamic acid solutions obtained in Synthesis Examples 10 to 12.

<Examples 7-9>

A thermoplastic polyimide film was obtained in the same manner as in Example 1 from the respective polyamic acid solutions obtained in Synthesis Examples 16 to 18.

For the obtained film, the moisture expansion rate for the thermal expansion coefficient and the weight change was measured, and the results are shown in Table 3 below.

At this time, the coefficient of thermal expansion was measured using TMA, the moisture content of the change in weight was measured by the method of ASTM D570.

Item Thermal expansion coefficient (ppm / ℃) Moisture Content (%) Example 1 2 3 4 5 6 7 8 9 40 45 58 42 48 57 45 51 58 1.0 0.8 0.7 0.7 0.8 0.5 0.3 0.5 0.9 Comparative Example 1 2 3 4 5 6 7 8 9 25 28 28 28 27 29 24 27 29 2.5 2.1 2.1 2.3 2.4 2.4 2.1 2.5 2.5

From the results of Table 3, it can be seen that the polyimide film of the present invention exhibits a coefficient of expansion similar to that of copper foil with a coefficient of thermal expansion of 10 to 100 ppm / ° C., and has a low hygroscopicity with a moisture content of 2% or less. It can be seen.

<Examples 10-18 and Comparative Examples 10-18>

Each of the polyimide films obtained from Examples 1 to 9 and Comparative Examples 1 to 9 was laminated with a non-thermoplastic polyimide base film (25NPI, manufactured by Kaneka) to evaluate the adhesive force with the base film.

Specifically, each polyimide obtained from Examples 1 to 9 and Comparative Examples 1 to 9 was cut to a 200 mm × 200 mm standard and laminated on a non-thermoplastic polyimide base film cut to an equivalent standard to 150 ° C. to At 350 ° C., compression heating was performed at a pressure of 100 to 1,000 kgf. The adhesion was then measured by the method of IPC 650.

The results are shown in Table 4 below.

Thermoplastic polyimide film Adhesion with Base Film (kgf / cm) Example 10 Example 1 1.0 11 Example 2 1.0 12 Example 3 1.2 13 Example 4 0.9 14 Example 5 1.1 15 Example 6 1.2 16 Example 7 0.9 17 Example 8 1.2 18 Example 9 1.3 Comparative Example 10 Comparative Example 1 0.3 11 Comparative Example 2 0.4 12 Comparative Example 3 0.4 13 Comparative Example 4 0.2 14 Comparative Example 5 0.3 15 Comparative Example 6 0.4 16 Comparative Example 7 0.1 17 Comparative Example 8 0.4 18 Comparative Example 9 0.4

From the results of Table 4, it can be seen that the thermoplastic polyimide film of the present invention is excellent in adhesive strength with the base film, and can be usefully used as an adhesive layer such as an adhesive layer for FPC production and a flexible copper foil laminate. It can also be seen that it can also be useful as a bonding sheet for a multilayer soluble printed wiring board.

As described in detail above, according to the present invention, a thermoplastic polyimide film obtained by mixing TPER and BAPP as diamines and BSAA and BTDA as dianhydrides was prepared to form a polyamic acid, and then molded into a film. Excellent adhesion, glass transition temperature satisfies the range of 150 to 300 ℃, easy thermal bonding at low temperatures, thermal expansion coefficient of 10 to 100ppm / ℃, showing the same degree of expansion as copper foil, and also with the base film It is excellent in adhesive strength and the like, and is useful for producing a two-layer metal laminate using the same, and also useful as an adhesive layer such as a flexible copper foil laminate or a flexible printed wiring board, and as a laminate with a polyimide base film. It can be prepared and used as an adhesive sheet.

Claims (6)

0.25 to 90.25 mol% of the repeating unit represented by the following Chemical Formula 1, 0.25 to 90.25 mol% of the repeating unit represented by the following Chemical Formula 2, 0.25 to 90.25 mol% of the repeating unit represented by the following Chemical Formula 3 and the repeating unit represented by the following Chemical Formula 4. Thermoplastic polyimide film consisting of polyimide having a molecular weight of 5,000 to 10,000,000, including 0.25 to 90.25 mol%. Formula 1

Formula 2

Formula 3

Formula 4

In Formulas 1 to 4, l, m, n, and o are positive integers of 1 or more. The thermoplastic polyimide film of claim 1, wherein the glass transition temperature is 150 to 300 ° C and the thermal expansion coefficient is 30 to 100 ppm / ° C. The thermoplastic polyimide film of claim 1, wherein the moisture content is 2% or less due to weight change measured according to ASTM 570. The polyimide laminated body by which the thermoplastic polyimide film of Claim 1 was laminated | stacked on at least one surface of the polyimide base film. The polyimide laminate according to claim 4, wherein the thermoplastic polyimide film satisfies the adhesive strength of 0.5 kgf / cm or more upon compression heating at 150 to 350 ° C. at a pressure of 100 to 1,000 kgf after being laminated with the polyimide substrate film. sieve. A multilayer flexible printed wiring board bonded by using the thermoplastic polyimide film of claim 1 as a bonding sheet.