KR20210145696A - Polyimide film - Google Patents

Abstract

The present invention relates to a polyimide film which has excellent dimensional stability and is very suitable for a substrate for a fine pitch circuit, particularly for a chip on film (COF) wired with a narrow pitch in the film width direction, and a copper clad laminate using the polyimide film as a substrate. The polyimide film is obtained by using an aromatic diamine ingredient including para-phenylene diamine and an acid anhydride ingredient, shows a heat expansion coefficient (α_MD) in the machine direction of the film of equal to or more than 2.0 ppm/℃ and less than 10.0 ppm/℃ and a heat expansion coefficient (α_TD) in the transverse direction of equal to or more than -2.0 ppm/℃ and equal to or less than 3.5 ppm/℃, as determined by using TMA-50 available from Shimatsu Co. at a temperature of 50-200℃ with a heating rate of 10℃/minute, and satisfies the relationship of ｜α_MD｜>=｜α_TD｜×2.0.

Description

polyimide film {POLYIMIDE FILM}

The present invention relates to a polyimide film excellent in dimensional stability and suitable for a fine-pitch circuit board, particularly, a COF (Chip on Film) wired at a narrow pitch in the film width direction, and a copper-clad laminate using the same as a base material. .

With the increase in the fineness of flexible printed circuit boards and semiconductor packages, the requirements for polyimide films used for them are also increasing. There are high properties, and as the physical properties of the polyimide film, a film having a metal-level coefficient of thermal expansion and a high modulus of elasticity, furthermore, a film with small dimensional change due to absorption is required. This has been developed

For example, in order to raise an elastic modulus, the example of the polyimide film using para-phenylene diamine is known (patent document 1, 2, 3). Moreover, in order to reduce the dimensional change due to water absorption while maintaining high elasticity, the example of the polyimide film using para-phenylene diamine and biphenyl tetracarboxylic dianhydride is known (patent document 4, 5).

Furthermore, in order to suppress the dimensional change in the metal bonding process, the thermal expansion coefficient in the machine transport direction (hereinafter referred to as MD) of the film is set smaller than the thermal expansion coefficient in the width direction (hereinafter referred to as TD) of the film to reduce anisotropy. The example of the polyimide film which gave it is known. Usually, in the FPC process, lamination method in which bonding with metal is performed by heating roll-to-roll is adopted. In this process, tension is applied to the MD of the film to cause elongation, while shrinkage occurs in TD. It aims to offset the (patent document 6).

However, in recent years, as a response to wiring miniaturization, a two-layer type (a copper layer formed directly on a polyimide film) that does not use an adhesive is adopted as a copper-clad laminate. There are a method of forming a copper layer by plating on a film, and a method of imidizing after casting polyamic acid on a copper foil, but neither is a thermocompression process like the lamination method. There is no need to make the coefficient of thermal expansion smaller than that of TD, and furthermore, for COF applications that are predominant in the two-layer type, a pattern in which a narrow pitch is wired to the TD of the film is common. Conversely, if the coefficient of thermal expansion of TD is large, The dimensional change between wirings increased during bonding, etc., making it difficult to meet the demand for finer pitch. To cope with this, it is ideal to make the coefficient of thermal expansion of the film small enough to approximate that of silicon, but there is a problem that deformation occurs due to the heating process starting at the time of chip mounting bonding because there is a difference in thermal expansion with copper.

Japanese Patent Laid-Open No. 60-210629 Japanese Patent Laid-Open No. 64-16832 Japanese Patent Laid-Open No. Hei1-131241 Japanese Patent Laid-Open No. 59-164328 Japanese Patent Laid-Open No. 61-111359 Japanese Patent Laid-Open No. 4-25434

does not exist

The present invention has been achieved as a result of examining the problem solving in the prior art described above as a problem, and a polyimide film suitable for a substrate for fine pitch circuits such as for COF, which can reduce the dimensional change of the film TD, and a base material for the same It aims at provision of the copper clad laminated body which was made into

The present invention relates to the following inventions.

[1] A polyimide film obtained using an aromatic diamine component containing paraphenylene diamine and an acid anhydride component, using TMA-50 manufactured by Shimadzu Corporation, in a measurement temperature range: 50 to 200°C, temperature rise rate _{: Thermal expansion coefficient α MD} in the machine transport direction (MD) of the film measured under the condition of 10° C./min is in the range of 2.0 ppm/° C. or more and less than 10.0 ppm/° C., and the thermal expansion coefficient α _TD in the width direction (TD) is In the range of -2.0 ppm/°C or more and 3.5 ppm/°C or less, _{the relation of |α MD} |≥|α _TD |×2.0 is satisfied. The polyimide film characterized by the above-mentioned.

[2] (alpha) _MD exists in the range of 3.0 ppm/degreeC or more and 9.5 ppm/degreeC or less, The polyimide film as described in said [1] characterized by the above-mentioned.

[3] α _TD is in the range of -1.5 ppm/°C or more and 3.0 ppm/°C or less, The polyimide film according to the above [1] or [2].

[4] The polyimide film according to any one of the above [1] to [3], wherein the MD and TD of the film have both heat shrinkage at 200°C of 0.05% or less.

[5] The polyimide film according to any one of the above [1] to [4], wherein the MD and TD of the film have heat shrinkage at 200°C of 0.03% or less.

[6] The polyimide film according to any one of [1] to [5] above, wherein the film has a tensile modulus of elasticity of 6.0 GPa or more.

[7] The polyimide film according to any one of [1] to [6], wherein the film has a water absorption of 3.0% or less.

[8] The polyimide film according to any one of [1] to [7], wherein the paraphenylene diamine is at least 31 mol% or more in the wholly aromatic diamine component.

[9] Furthermore, as an aromatic diamine component, the above [1]- The polyimide film according to any one of [8].

[10] The above [1] to [9] wherein the acid anhydride component is at least one selected from the group consisting of pyromellitic dianhydride and 3,3'-4,4'-diphenyl tetracarboxylic dianhydride The polyimide film according to any one of claims.

[11] A copper-clad laminate characterized by using the polyimide film as described in any one of [1] to [10] above.

[12] A film was prepared using an aromatic diamine component containing para-phenylene diamine and an acid anhydride component, and the resulting gel film was stretched in the machine conveying direction at a draw ratio (MDX) of 1.05 to 1.6 times, in the machine conveying direction The method for producing the polyimide film according to any one of [1] to [10], characterized in that it has a step of stretching in the width direction at a draw ratio (TDX) of 1.1 to 1.5 times the draw ratio of .

[13] A substrate for COF, wherein the polyimide film as described in any one of [1] to [10] is used.

The polyimide film of this invention can suppress generation|occurrence|production of the dimensional change in a COF manufacturing process effectively. Further, the polyimide film of the present invention can suppress the coefficient of thermal expansion in the above direction low by advancing the orientation of the film to TD, furthermore, the heat shrinkage rate can be low, and high elasticity and high strength can be achieved.

The polyimide film of the present invention is a polyimide film obtained using an aromatic diamine component containing para-phenylene diamine and an acid anhydride component, using TMA-50 manufactured by Shimadzu Corporation, in a measurement temperature range: 50 to 200°C, temperature rise _{Speed: The thermal expansion coefficient α MD} in the machine transport direction (MD) of the film measured under the conditions of 10°C/min is in the range of 2.0 ppm/°C or more and less than 10.0 ppm/°C, and the thermal expansion coefficient α _{TD in the width direction (TD)} In the range of -2.0 ppm/°C or more and 3.5 ppm/°C or less, it is characterized in that the relation of _{|α MD} |≥|α _{TD |×2.0 is satisfied.}

_{The coefficient of thermal expansion α MD} in the machine transport direction (MD) of the polyimide film of the present invention is usually in the range of 2.0 ppm/°C or more and less than 10.0 ppm/°C, more preferably 3.0 ppm/°C or more and 9.5 ppm/°C or less. The range of 3.5 ppm/°C or more and 9.0 ppm/°C or less is still more preferable, and the range of 4.0 ppm/°C or more and 8.5 ppm/°C or less is particularly preferable.

_{The coefficient of thermal expansion α TD} in the width direction (TD) of the polyimide film of the present invention is usually in the range of -2.0 ppm/°C or more and 3.5 ppm/°C or less, and is particularly suitable for COF, so -1.5 ppm/°C or more The range of 3.0 ppm/°C or less is more preferable, the range of -1.0 ppm/°C or more and 2.5 ppm/°C or less is still more preferable, and the range of -0.5 ppm/°C or more and 2.0 ppm/°C or less is particularly preferable. When it is less than the said range, since intensity|strength (for example, tensile elongation etc.) is inferior and the film obtained becomes easy to crack, it is unpreferable. By making α _TD within the above range and combining with each component of the present invention, regardless of the partner to which the polyimide film is bonded for COF (for example, the partner to which the film is bonded is a metal (eg, copper)) However, since it has excellent dimensional stability (even if it is glass), the influence of the dimensional change on the film side can be suppressed small, and it is possible to design a high-definition COF circuit board.

The measurement conditions of the coefficients of thermal expansion α _MD and α _{TD in} the present invention are values measured under the conditions of a measurement temperature range of 50 to 200° C. and a temperature rise rate: 10° C./min using TMA-50 manufactured by Shimadzu Corporation. am.

The polyimide film of the present invention generally satisfies the relation of |α _MD |≥|α _{TD |×2.0 for the α MD} and the α _TD , and preferably |α _MD |≥|α _TD |× The relationship of 2.5 is satisfied, more preferably the relationship of |α _MD |≥|α _TD |×2.8 is satisfied, and still more preferably the relation |α _MD |≥|α _TD |×3.0 or more is satisfied. Further, although not particularly limited, _{it is preferable to satisfy the relation of |α MD} |≤|α _TD |×50.0, and more preferably satisfy the relation |α _MD |≦|α _TD |×30.0, and |α It is still more preferable to satisfy the relationship of _MD | ? | α _{TD | x 20.0.} If α _MD and α _TD are within the above range and satisfy the relationship of the above formula, conventionally, if the thermal expansion coefficient of the polyimide film and the bonding metal (for example, copper) are different, the difference in thermal expansion coefficient is The problem of thermal stress is large, and it has been thought that dimensional change is a problem in bonding with a metal. However, in bonding a polyimide film to a metal (eg, copper), the metal (eg, linear expansion of copper) Even if the coefficient is different from the coefficient of linear expansion of 17 ppm/°C), dimensional stability is not a problem.

It is preferable that both MD and TD are 0.05 % or less, and, as for the 200 degreeC heat shrinkage rate of the polyimide film of this invention, it is more preferable that both are 0.03 % or less.

6.0 GPa or more is preferable, as for the tensile modulus of elasticity of the polyimide film of this invention, 6.5 GPa or more is more preferable, 6.8 GPa or more is still more preferable. Further, both MD and TD are preferably 6.0 GPa or more, both MD and TD are more preferably 6.5 GPa or more, and both MD and TD have more preferably 6.8 GPa or more.

3.0 % or less is preferable and, as for the water absorption of the polyimide film of this invention, 2.8 % or less is more preferable.

The polyimide film of the present invention is not particularly limited, but from the viewpoint of good running properties of the TD oriented film, the tear propagation resistance is preferably 3.0 N/mm or more in both MD and TD, and more preferably 5.0 N/mm or more. do. The tear propagation resistance is a value measured using a light load tear tester similar to the Elmendorf tear method. The said measured value shows the point which is hard to tear considering the whole thickness direction from the point which has shown the resistance when a film is torn, and means that a film is hard to tear as much as it is large, and it is excellent in running property.

Less than 0.01 % is preferable and, as for the dimensional change rate of the polyimide film of this invention, 0.008 % or less is more preferable.

In manufacturing the polyimide film of this invention, a polyamic-acid solution is obtained by first superposing|polymerizing an aromatic diamine component and an acid anhydride component in an organic solvent.

The polyimide film of the present invention contains para-phenylene diamine as the aromatic diamine component. The aromatic diamine component may contain other than para-phenylene diamine, and specific examples of the aromatic diamine component other than para-phenylene diamine include metaphenylene diamine, bentidine, p-xylene diamine, 4,4'- Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl methane, 4,4'-diaminodiphenyl sulfone, 3,3'-dimethyl-4,4' -diaminodiphenyl methane, 1,5-diamino naphthalene, 3,3'-dimethoxy benzine, 1,4-bis(3-methyl-5 aminophenyl)benzene, and their amide-forming derivatives are mentioned. . These may be used individually by 1 type, and may mix and use 2 or more types. As the aromatic diamine component, a combination of para-phenylene diamine with 4,4'-diaminodiphenyl ether and/or 3,4'-diaminodiphenyl ether is preferable. Of these, by adjusting the amount of the diamine component of para-phenylene diamine and 3,4'-diaminodiphenyl ether, which has an effect of increasing the tensile modulus of the film, the tensile modulus of the resulting polyimide film is 6.0 GPa or more. , which is preferable because the transportability is also improved.

Specific examples of the acid anhydride component include pyromellitic acid, 3,3',4,4'-biphenyl tetracarboxylic acid, 2,3',3,4'-biphenyltetracarboxylic acid, 3,3', 4,4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 2,2-bis(3,4-dicarboxyphenyl)ether, pyridine-2,3,5,6- and aromatic tetracarboxylic anhydride components such as tetracarboxylic acid and such amide-forming derivatives, and pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride are preferable. These may be used individually by 1 type, and may mix and use 2 or more types.

Among these, when an aromatic diamine component and an acid anhydride component are combined, one selected from the group consisting of para-phenylene diamine, 4,4'-diaminodiphenyl ether and 3,4'-diaminodiphenyl ether and combinations of at least one aromatic diamine component and at least one acid anhydride component selected from the group consisting of pyromellitic dianhydride and 3,3',4,4'-biphenyl tetracarboxylic dianhydride.

The blending ratio (molar ratio) of para-phenylene diamine in the aromatic diamine component provides a suitable strength to the film and prevents poor running performance, while obtaining a coefficient of thermal expansion within the above range. In the wholly aromatic diamine component, Usually, it is at least 31 mol% or more, preferably 33 mol% or more, and more preferably 35 mol% or more.

Although it does not specifically limit as a compounding ratio (molar ratio) in the said acid anhydride component, unless the effect of this invention is impaired, For example, 3,3',4,4'- biphenyltetracarboxylic dianhydride When it contains, 15 mol% or more is preferable, as for content of 3,3',4,4'- biphenyl tetracarboxylic dianhydride, 20 mol% or more is more preferable, and 25 mol% or more is still more preferable.

When the polyimide film, which is a basic material, is produced from a polyamic acid comprising such an aromatic diamine component and an acid anhydride component, the coefficient of thermal expansion of the polyimide film in the machine transport direction (MD) and width direction (TD) of the film is within the above range. It is preferable because it can be easily adjusted.

In the present invention, specific examples of the organic solvent used for forming the polyamic acid solution include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, N,N-dimethyl formamide, and N,N-diethyl Formamide solvents such as formamide, acetamide solvents such as N,N-dimethyl acetamide and N,N-diethyl acetamide, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolid Pyrrolidone solvents such as done, phenolic solvents such as phenol, o-, m- or p-cresol, xylenol, halogenated phenol, catechol, or beef such as hexamethyl phosphoramide and γ-butyrolactone Tonic polar solvents are mentioned, and it is preferable to use these alone or as a mixture using two or more, but further, aromatic hydrocarbons such as xylene and toluene can be used.

The polymerization method may be any known method, for example,

(1) First, the whole amount of the aromatic diamine component is put in a solvent, and then the acid anhydride component is added so as to have an equivalent weight (equimolar) with the total amount of the aromatic diamine component, followed by polymerization.

(2) First, the entire amount of the acid anhydride component is placed in a solvent, and then the aromatic diamine component is added so as to be equivalent to the acid anhydride component, followed by polymerization.

(3) After putting one aromatic diamine component (a1) in a solvent, one side of the acid anhydride component (b1) is 95 to 105 mol% with respect to the reaction component After mixing for the time required for the reaction, one aromatic A method of polymerization by adding the diamine component (a2), then adding the other acid anhydride component (b2) so that the wholly aromatic diamine component and the total acid anhydride component are approximately equivalent.

(4) After putting one acid anhydride component (b1) in a solvent, one aromatic diamine component (a1) with respect to the reaction component is mixed for the time required for the reaction in a ratio of 95 to 105 mol%, and then the other A method of polymerization by adding an acid anhydride component (b2), then adding the other aromatic diamine component (a2) so that the wholly aromatic diamine component and the total acid anhydride component are approximately equivalent.

(5) A polyamic acid solution (A) is prepared by reacting one of the aromatic diamine components and the acid anhydride component in an excess of either of the solvents, and the other aromatic diamine component and the acid anhydride component in the other solvent It is made to react so that it may become excess, and a polyamic-acid solution (B) is adjusted. The method of mixing each polyamic-acid solution (A) and (B) obtained in this way, and completing superposition|polymerization. At this time, when the aromatic diamine component is excessive in adjusting the polyamic acid solution (A), the acid anhydride component is excessive in the polyamic acid solution (B), and the acid anhydride component is excessive in the polyamic acid solution (A), In the polyamic acid solution (B), the aromatic diamine component is excessive, and the polyamic acid solution (A) and (B) are mixed, and the total aromatic diamine component and the total acid anhydride component used in these reactions are adjusted to be almost equivalent. do. In addition, the polymerization method is not limited to these, You may use other well-known methods.

The polyamic acid solution obtained in this way contains 5 to 40 weight% of solid content normally, Preferably it contains 10 to 30 weight% of solid content. In addition, the viscosity is 10-2000 Pa.s normally in the measured value by a Brookfield viscometer, and for stable liquid feeding, Preferably it is 100-1000 Pa.s. In addition, in the organic solvent solution, the polyamic acid may be imidated partially.

Next, the manufacturing method of a polyimide film is demonstrated. As a method of forming a polyimide film, a method of obtaining a polyimide film by casting a polyamic acid solution into a film and thermally decyclizing and desolving it, and a method of chemically decyclizing a polyamic acid solution by mixing a cyclization catalyst and a dehydrating agent A method of obtaining a polyimide film by making a gel film is produced by heating and desolvation by heating, but the latter is preferable because the coefficient of thermal expansion of the obtained polyimide film can be suppressed to a low level.

In the method of chemically decyclizing, the above-mentioned polyamic acid solution is prepared first. In addition, this polyamic-acid solution can contain chemically inactive organic fillers and inorganic fillers, such as a titanium oxide, a silica, a calcium carbonate, a calcium phosphate, a calcium hydrogen phosphate, and a polyimide filler, as needed. Content of a filler is not specifically limited unless the effect of this invention is impaired.

The polyamic-acid solution used here may be the polyamic-acid solution which superposed|polymerized previously, or what superposed|polymerized sequentially when making a filler particle contain it may be sufficient as it.

Said polyamic acid solution can contain a cyclization catalyst (imidization catalyst), a dehydrating agent, a gelation retarder, etc.

Specific examples of the cyclization catalyst used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylenediamine, aromatic tertiary amines such as dimethyl aniline, and heterocyclic rings such as isoquinoline, pyridine and beta picoline Although tertiary amine etc. are mentioned, A heterocyclic tertiary amine is preferable. These may be used individually by 1 type, and may mix and use 2 or more types.

Specific examples of the dehydrating agent used in the present invention include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Acetic anhydride and/or benzoic anhydride are preferred. do. It does not specifically limit as a gelation retardant, Acetylacetone etc. can be used.

As a method for producing a polyimide film from a polyamic acid solution, the polyamic acid solution containing the above cyclization catalyst and the above dehydrating agent is cast into a film from a clasp with a slit on a support, molded into a film, and already on the support. A method of performing heat treatment by partially advancing de-forming to obtain a gel film having self-supporting properties, then peeling from the support and drying/imidating by heat is exemplified.

The above-mentioned support is a metal rotating drum or endless belt, the temperature of which is controlled by heat of liquid or gas and/or by radiant heat such as an electric heater.

The gel film is heated to usually 30 to 200° C., preferably 40 to 150° C. by water heat from a support and/or heat from a heat source such as hot air or an electric heater for a ring closure reaction, and free By drying the volatile matter such as an organic solvent, it has self-supporting properties and is peeled from the support body.

Although the gel film peeled from the said support body is not specifically limited, Usually, it is preferable to extend|stretch in a conveyance direction while regulating a traveling speed with a rotating roll. Extending|stretching to a conveyance direction is performed at the temperature of 140 degrees C or less. The draw ratio (MDX) is 1.05 to 1.9 times normally, Preferably it is 1.1 to 1.6 times, More preferably, it is 1.1 to 1.5 times. The gel film stretched in the conveyance direction is introduced into a tenter device, and both ends in the width direction are gripped by the tenter clip, and the gel film is stretched in the width direction while traveling together with the tenter clip. Extending|stretching to the width direction is performed at the temperature of 200 degreeC or more. The draw ratio (TDX) is 1.1 to 1.5 times of MDX normally, Preferably it is 1.2 to 1.45 times. With respect to the gel film obtained by said mixing|blending, by implementing this draw ratio combination, it orientates in film TD, and the film which has the effect of this invention can be obtained.

The film dried in said drying zone is heated for 15 second - 10 minutes by a hot air, an infrared heater, etc. Next, heat treatment is performed for 15 seconds to 20 minutes at a temperature of 250 to 500°C by hot air and/or an electric heater.

Moreover, although running speed is adjusted and the thickness of a polyimide film is adjusted, as thickness of a polyimide film, in order to prevent deterioration of film forming property, 3-250 micrometers is preferable, and 5-150 micrometers is more preferable.

It is preferable to further anneal the polyimide film obtained in this way. By doing so, thermal relaxation of the film occurs and it is possible to suppress the heat shrinkage rate small. Although it does not specifically limit as temperature of annealing, 200 degreeC or more and 500 degrees C or less are preferable, 200 degrees C or more and 370 degrees C or less are more preferable, 210 degreeC or more and 350 degrees C or less are especially preferable. In the manufacturing method of the polyimide film of the present invention, since the orientation in the film TD is strong, the heat shrinkage rate in this direction tends to increase that much. Since there is a number, it is preferable that the dimensional accuracy is further increased. Specifically, it is preferable to carry out annealing treatment by running the film under low tension in the furnace heated to the above temperature range. Although the time for which a film stays in a furnace becomes processing time, it is controlled by changing a traveling speed, and it is preferable that it is processing time of 30 second - 5 minutes. When it is shorter than this, heat cannot fully transmit to a film, and when it is long, since it becomes a tendency for overheating and impairs planarity, it is unpreferable. Moreover, 10-50 N/m is preferable and, as for the film tension at the time of running, 20-30 N/m is more preferable. When the tension is lower than this range, the running property of the film deteriorates, and when the tension is high, the thermal contraction rate in the running direction of the obtained film is increased, which is not preferable.

In addition, in order to give the obtained polyimide film adhesiveness, it is not specifically limited, You may carry out electrical treatment like corona treatment and plasma treatment, or physical treatment like blast treatment on the film surface. Although the pressure of the atmosphere in the case of plasma processing is not specifically limited, Usually, the range of 13.3-1330 kPa, the range of 13.3-133 kPa (100-1000 Torr) is preferable, 80.0-120 kPa (600-900 Torr) The range of is more preferable.

The atmosphere for plasma treatment contains at least 20 mol% of an inert gas, preferably contains 50 mol% or more of inert gas, more preferably contains 80 mol% or more, and most preferably contains 90 mol% or more desirable. Said inert gas contains He, Ar, Kr, Xe, Ne, Rn, N2, and a mixture of these 2 or more types. A particularly preferred inert gas is Ar. Furthermore, with respect to the above inert gas, oxygen, air, carbon monoxide, carbon dioxide, carbon tetrachloride, chloroform, hydrogen, ammonia, tetrafluoromethane (carbon tetrafluoride), trichlorofluoroethane, trifluoromethane, etc. may be mixed. . Preferred combinations of mixed gases used as the atmosphere for plasma treatment of the present invention are argon/oxygen, argon/ammonia, argon/helium/oxygen, argon/carbon dioxide, argon/nitrogen/carbon dioxide, argon/helium/nitrogen, argon/helium. /nitrogen/carbon dioxide, argon/helium, helium/air, argon/helium/monosilane, argon/helium/disilane, etc. are mentioned.

The processing power density at the time of plasma treatment is not particularly limited, but preferably 200 W·min/m2 or more, more preferably 500 W·min/m2 or more, and most preferably 1000 W·min/m2 or more. . The plasma irradiation time for plasma treatment is preferably 1 second to 10 minutes. By setting the plasma irradiation time within this range, the effect of the plasma treatment can be sufficiently exhibited without deterioration of the film. The gas type, gas pressure, and processing density of plasma processing are not limited to the above conditions, and may be performed in the atmosphere.

In the polyimide film obtained in this way, by advancing the orientation of the film in the TD direction, the coefficient of thermal expansion in this direction can be suppressed low, and the heat shrinkage rate is also low and the high tensile elasticity modulus is maintained. It is very suitable for circuit boards, especially for COF (Chip on Film) that is wired at a narrow pitch to the TD of the film.

Moreover, the copper-clad laminate of this invention can be obtained by using the polyimide film characterized by any of the above as a base material, and forming copper with a thickness of 1-10 micrometers on this.

This invention includes the aspect which combined various said structures within the technical scope of this invention as long as the effect of this invention is shown.

[Example]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples, and many modifications can be made within the technical spirit of the present invention. It is possible by people with

Incidentally, in the Examples, PPD represents para-phenylene diamine, 4,4'-ODA represents 4,4'-diamine diphenyl ether, PMDA represents pyromellitic dianhydride, BPDA represents 3,3', 4,4'-biphenyl tetracarboxylic dianhydride and DMAc represent N,N-dimethyl acetamide, respectively.

In addition, each characteristic in an Example was evaluated by the following method.

(1) Coefficient of thermal expansion

Apparatus: TMA-50 (trade name, manufactured by Shimadzu Corporation) was used, and measurement was performed under the conditions of a measurement temperature range: 50 to 200°C, and a temperature rise rate: 10°C/min.

(2) Heating shrinkage

Measure the film dimension (L1) after leaving it for 2 days in a room adjusted to 25°C and 60%RH, and then heated at 200°C for 60 minutes and then left in a room adjusted to 25°C and 60%RH for 2 days. The post film dimension (L2) was measured and evaluated by the formula calculation described below.

Heat shrinkage rate (%) = -｛(L2-L1)/L1｝×100

(3) Tensile modulus

Apparatus: RTM-250 (trade name, made by A&D) was used, and it measured on the conditions of tensile speed|rate: 100 mm/min.

(4) Dimensional change rate

A copper layer with a thickness of 10 μm is formed on the film by electrolytic plating with a copper sulfate plating solution, pattern etched at a pitch of 30 μm (line spacing 15 μm), and copper is wired to the TD, followed by electroless tin plating LT34 manufactured by Shippeist. tin plating was performed, and the dimensions at this time were measured (L3). This was placed on a bonding stage at 250°C, and the dimensions after bonding to the chip with a bonding tool at 400°C were measured (L4). The dimensional change rate was calculated|required by the formula described below.

Dimensional change rate (%) =｛(L4-L3)/L3｝×100

(5) Tear propagation resistance

A 63.5 mm x 50 mm test piece was prepared from a polyimide film, what was cut to 12.7 mm in length was put in the test piece, and it measured based on 　 JIS P8116 using the light load cutting tester made by Dongyang Seiki.

(6) Absorption rate

After immersing the film in distilled water for 48 hours, it was taken out, and the water on the surface was quickly wiped off, and the sample was cut into a size of about 5 mm x 15 mm. After the film was applied to Shou Electric, it was measured with a thermogravimetric analyzer TG-50 manufactured by Shimadzu Corporation. The rate of temperature increase was 10°C/min to 200°C, and the water absorption was calculated from the change in weight using the following formula.

Water absorption (%) = ｛ (weight before heating) - (weight after heating) ｝/(weight after heating) x 100

[Example 1]

Put 239.1 g of DMAc in a 500 ml separable flask, PPD 5.68 g (0.053 mol), 4,4'-ODA 19.56 g (0.097 mol), BPDA 11.56 g (0.0375 mol), PMDA 22.95 g (0.1132 mol) It was put, and it was made to react in normal temperature and normal pressure for 1 hour, and it stirred until it became uniform, and the polyamic-acid solution was obtained.

After extracting 15 g from this polyamic-acid solution and cooling to minus 5 degreeC, the liquid mixture was obtained by mixing 1.5 g of acetic anhydride and 1.6 g of (beta)-picolin.

After casting the thus-obtained liquid mixture on a rotating drum at 90°C for 30 seconds, the resulting gel film was stretched 1.12 times in the traveling direction while heating at 100°C for 5 minutes. Subsequently, both ends in the width direction were gripped and stretched 1.4 times in the width direction while heating at 270°C for 2 minutes, and then heated at 380°C for 5 minutes to obtain a polyimide film having a thickness of 38 µm. After applying the tension of 20 N/m to this polyimide film in the furnace set to 220 degreeC, and annealing it for 1 minute, each characteristic was evaluated.

The coefficient of thermal expansion of the film _MD MD α: 9.0 ppm / ℃

The thermal expansion coefficient α of the film TD _TD: 3.0 ppm / ℃

200℃ heating shrinkage (MD)　　: 0.02%

200℃ heating shrinkage (TD)　　: 0.01%

Tensile modulus (MD)　　　　　　: 6.5 GPa

Tensile modulus (TD)　　　　　　: 8.0 GPa

Tear propagation resistance (MD)　　　　　: 6.7 N/mm

Tear propagation resistance (TD)　　　　　: 5.6 N/mm

Dimensional change rate　　　　　　　　: 0.006%

Absorption rate　　　　　　　　　　: 2.3%

[Examples 2 to 6]

In the same procedure as in Example 1, the aromatic diamine component and the aromatic tetracarboxylic acid component were each obtained in a ratio shown in Table 1 to obtain a polyamic acid solution, and then the draw ratios in the transverse and vertical directions were performed as shown in Table 1, in Example 1 Each characteristic evaluation of the polyimide film obtained by operation similar to was performed, and the result was shown in Table 1.

Example One 2 3 4 5 6

proportion of each raw material
(molar ratio)
PPD:35
4,4'-ODA:65
BPDA:25
PMDA:75 PPD:40
4,4'-ODA:60
BPDA:25
PMDA:75 PPD:45
4,4'-ODA:55
BPDA:25
PMDA:75 PPD:35
4,4'-ODA:65
BPDA:35
PMDA:65 PPD:40
4,4'-ODA:60
BPDA:35
PMDA:65 PPD:45
4,4'-ODA:55
BPDA:35
PMDA:65

draw ratio

MDX

1.12
1.13
1.12
1.10
1.12
1.12
TDX

1.40
1.40
1.40
1.45
1.43
1.40

coefficient of thermal expansion
(ppm/℃)
MD

9.0
6.5
3.5
9.5

6.6
3.8
TD

3.0
1.5
0.2
3.1
1.6
0.4

Heat shrinkage
(%)
MD

0.02
0.02
0.01
0.02
0.02
0.01
TD

0.01
0.02
0.01
0.02
0.01

0.01

tensile modulus
(GPa)
MD

6.5

7.3
8.0
6.4
7.0
7.8
TD

8.0
9.0
9.7
7.8
8.8
9.5

tear propagation resistance
(N/mm)

MD

6.7
6.9
7.1
6.7
6.8
7.0
TD

5.6
5.3
5.2
5.3
5.3
5.1
Dimensional change rate (%)

0.006
0.008
0.000
0.006
0.004
0.001
Absorption rate (%)

2.3
2.4
2.5
2.1
2.3
2.5

(The molar ratio in the table indicates the mole % in the wholly aromatic diamine component and the mole % in the total acid anhydride component, respectively.) 239.1 g of DMAc was placed in a 500 ml separable flask, and PPD 4.65 g (0.043 mole), 4,4'-ODA 21.08 g (0.105 mol), BPDA 10.91 g (0.031 mol), PMDA 24.26 g (0.111 mol) were put, reacted at room temperature and normal pressure for 1 hour, stirred until uniform, and polyamic acid solution was prepared got it

After extracting 15 g from this polyamic-acid solution and cooling to minus 5 degreeC, the liquid mixture was obtained by mixing 1.5 g of acetic anhydride and 1.6 g of (beta)-picoline.

After cast|flow_spreading the liquid mixture obtained in this way to a 90 degreeC rotating drum for 30 second, it extended|stretched 1.1 times in the running direction, heating the obtained gel film at 100 degreeC for 5 minutes. Subsequently, both ends in the width direction were gripped and stretched 1.4 times in the width direction while heating at 270°C for 2 minutes, and then heated at 380°C for 5 minutes to obtain a polyimide film having a thickness of 38 µm. After annealing this polyimide film for 1 minute over the tension|tensile_strength of 20 N/m in the furnace set to 220 degreeC, each characteristic was evaluated.

[Comparative Examples 1 and 2]

In the same procedure as in Example 1, the aromatic diamine component and the aromatic tetracarboxylic acid component were each obtained in a polyamic acid solution in the ratio shown in Table 2, and then the draw ratios in the transverse and vertical directions were performed as shown in Table 2 in Example 1 Each characteristic evaluation of the polyimide film obtained by operation similar to was performed, and the result was shown in Table 2.

comparative example One 2
proportion of each raw material
(molar ratio)
PPD 30
4,4'-ODA 70
BPDA 30
PMDA 70 PPD 20
4,4'-ODA 80
BPDA 30
PMDA 70

draw ratio

MDX

1.13
1.20
TDX

1.40
1.40

coefficient of thermal expansion
(ppm/℃)
MD

12.0
16
TD

4.8
13

Heat shrinkage
(%)
MD

0.02
0.02
TD

0.01
0.02

tensile modulus
(GPa)
MD

5.7
5.3
TD

7.0
5.8

tear propagation
(N/mm)

MD

6.7
7.5
TD

5.6
7.5
Dimensional change rate (%)

0.010
0.025
Absorption rate (%)

2.0
1.7

(The molar ratio in the table shows the mole % in the wholly aromatic diamine component and the mole % in the total acid anhydride component, respectively.)

The polyimide film of this invention can be used suitably for the board|substrate for fine-pitch circuits, especially COF (Chip-on film) wired in narrow pitch by TD of a film.

Claims (13)

A polyimide film obtained by using an aromatic diamine component containing para-phenylene diamine and an acid anhydride component, using TMA-50 manufactured by Shimadzu Corporation, in a measurement temperature range: 50 to 200°C, temperature rise rate: 10°C/min. is in the range of the thermal expansion coefficient α _MD is 2.0 ppm / ℃ to less than 10.0 ppm / ℃ of the machine conveying direction (MD) of the film was measured under the conditions, the coefficient of thermal expansion α _TD in the transverse direction (TD) -2.0 ppm / ℃ It exists in the range of more than 3.5 ppm/degreeC or less, and _{the relationship of |α MD} |≥|α _TD |×2.0 is satisfied. The polyimide film characterized by the above-mentioned.
The polyimide film according to claim 1, wherein α _MD is in a range of 3.0 ppm/°C or more and 9.5 ppm/°C or less.
The polyimide film according to claim 1 or 2, wherein α _TD is in the range of -1.5 ppm/°C or more and 3.0 ppm/°C or less.
The polyimide film according to any one of claims 1 to 3, wherein both MD and TD of the film have heat shrinkage at 200°C of 0.05% or less.
The polyimide film according to any one of claims 1 to 4, wherein both MD and TD of the film have heat shrinkage at 200°C of 0.03% or less.
The polyimide film according to any one of claims 1 to 5, wherein the film has a tensile modulus of elasticity of 6.0 GPa or more.
The polyimide film according to any one of claims 1 to 6, wherein the film has a water absorption of 3.0% or less.
The polyimide film according to any one of claims 1 to 7, characterized in that para-phenylene diamine is at least 31 mol% or more in the wholly aromatic diamine component.
The method according to any one of claims 1 to 8, further comprising at least one selected from the group consisting of 4,4'-diamino diphenyl ether and 3,4'-diamino diphenyl ether as an aromatic diamine component. Characterized in the polyimide film.
10. The method according to any one of claims 1 to 9, wherein the acid anhydride component is at least one selected from the group consisting of pyromellitic dianhydride and 3,3'-4,4'-diphenyl tetracarboxylic dianhydride. which is a polyimide film.
The polyimide film in any one of Claims 1-10 is used, The copper clad laminated body characterized by the above-mentioned.
A gel film was prepared using an aromatic diamine component containing para-phenylene diamine and an acid anhydride component, and the resulting gel film was stretched in the machine transport direction at a draw ratio (MDX) of 1.05 to 1.6 times, and then stretched in the machine transport direction. It has a process of extending|stretching in the width direction at the draw ratio (TDX) of 1.1 to 1.5 times the magnification, The manufacturing method of the polyimide film in any one of Claims 1-10 characterized by the above-mentioned.
A substrate for COF, characterized in that the polyimide film according to any one of claims 1 to 10 is used.