JP2016132744A - Polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyimide film capable of reducing a dimension change in a width direction (TD) of a film, and favorable for a substrate for a fine pitch circuit such as a chip-on-film (COF) using a semi-additive method.SOLUTION: The polyimide film is constituted by paraphenylenediamine, pyromellitic acid dianhydride, and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride used as principal raw materials where protrusions of a surface of the polyimide film is formed of inorganic particles having an average particle size of 0.01-1 μm, the heat expansion coefficient αof the film in a machine-conveying direction (MD) measured under the condition of a measuring range of 50-200°C and a temperature-raising rate of 10°C/min. is within a range of 2.0-10.0 ppm/°C, the heat expansion coefficient αof TD is within a range of 2.0-3.5 ppm/°C, and the relation |α|≥|α|×2.0 is satisfied.SELECTED DRAWING: None

Description

  The present invention is a polyimide film suitable for COF (Chip on Film, chip-on-film) using a semi-additive method that has excellent dimensional stability and is fine pitch circuit substrate, in particular, a narrow pitch wiring in the film width direction. Further, the present invention relates to a COF substrate in which a wiring circuit is formed on a polyimide film by etching a copper-clad laminate having a base material as a base material, and further etching a copper layer of the copper-clad laminate.

  As flexible printed circuit boards (FPCs) and semiconductor packages become more sophisticated, there are increasing requirements for polyimide films used in them, for example, reducing dimensional changes and curling due to bonding with metal, and handling properties. The polyimide film properties are required to have a coefficient of thermal expansion comparable to that of a metal, to have a high elastic modulus, and to have a small dimensional change due to water absorption. It has been.

  For example, examples of polyimide films using paraphenylenediamine to increase the elastic modulus are known (Patent Documents 1, 2, and 3). Moreover, in order to reduce the dimensional change by water absorption, maintaining the high elasticity, the example of the polyimide film which uses biphenyltetracarboxylic dianhydride in addition to paraphenylenediamine is known (patent documents 4 and 5).

  Furthermore, in order to suppress the dimensional change in the bonding process with the metal, the thermal expansion coefficient in the machine transport direction (hereinafter also referred to as MD) of the film is smaller than the thermal expansion coefficient in the width direction of the film (hereinafter also referred to as TD). Examples of polyimide films that are set and have anisotropy are known. In the normal FPC manufacturing process, a lamination method is used in which bonding with metal is performed by heating with roll-to-roll, and the MD of the film in this process is stretched due to tension, while TD Is intended to cancel the phenomenon of shrinkage (Patent Document 6).

By the way, in recent years, in response to the miniaturization of wiring, a two-layer type (in which a copper layer is directly formed on a polyimide film) that does not use an adhesive has been adopted as a copper laminate. As a manufacturing method of this two-layer type copper clad laminate, there are a method of forming a copper layer by a plating method on a film and a method of imidizing after casting a polyamic acid on a copper foil, both of which are laminations. Since it is not based on thermocompression bonding as in the method, it is no longer necessary to make the thermal expansion coefficient of the MD of the film smaller than the thermal expansion coefficient of TD.
In particular, in the COF application, which is the mainstream in the two-layer type, a pattern that is wired at a narrow pitch on the TD of the film is common. The dimensional change has increased, making it difficult to meet the demand for fine pitch. In particular, in recent years, as a method for forming a wiring pattern, a seed layer is formed in advance on an insulating substrate, a photoresist is formed, and the photoresist layer is subjected to selective exposure and development treatment, and then patterned into a wiring shape. COF using a semi-additive method, which consists of the process of removing the photoresist after forming the wiring on the seed layer by electroless plating or electrolytic plating as the plating mask, and etching away the seed layer at portions other than the wiring, is adopted. Since a rectangular pattern can be obtained with an arbitrary conductor thickness, pattern miniaturization is easier than in the conventional subtractive method, which is a wiring pattern formation method, and fine pitching is further accelerated. (Patent Document 7). To cope with this, it is ideal to make the thermal expansion coefficient of the film as small as approximating that of silicon. There is a problem that distortion occurs.

JP-A-60-210629 JP-A 64-16832 JP-A-1-131241 JP 59-164328 A JP-A-61-111359 JP-A-4-25434 JP 2008-211045 A

  The present invention has been made as a result of studying the solution of the above-described problems in the prior art, and can reduce the dimensional change of the film TD, and can be used for a fine pitch circuit such as for COF using a semi-additive method. The object is to provide a polyimide film suitable for a substrate for use in a semiconductor and a copper-clad laminate using the polyimide film as a base material.

The present invention relates to the following inventions.
[1] A polyimide film used for a chip-on film including a copper wiring portion having a pitch of 10 to 40 μm by a semi-additive method and formed with a wiring so that an IC chip can be mounted. Consists of p-phenylenediamine as the aromatic diamine component, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as the main ingredients. And the protrusions on the surface of the polyimide film are formed from inorganic particles having an average particle diameter of 0.01 to 1 μm, and using TMA-50 manufactured by Shimadzu Corporation, measurement range: 50 to 200 ° C., Rate of temperature increase: Thermal expansion coefficient α _{MD in} the machine transport direction (MD) of the film measured at 10 ° C./min is 2.0 ppm / ° C. to 10.0 ppm / ° C. In the range, the coefficient of thermal expansion α _{TD in} the width direction (TD) is in the range of −2.0 ppm / ° C. to 3.5 ppm / ° C., and the relationship of | α _MD | ≧ | α _TD | × 2.0 A polyimide film characterized by filling.
[2] The polyimide film as described in [1], wherein the paraphenylenediamine is at least 31 mol% or more in the wholly aromatic diamine component.
[3] The polyimide film according to any one of [1] to [2], wherein the surface roughness Ra and Rz of the film are in a range of 10 nm or less and 100 nm or less, respectively.
[4] A copper-clad laminate, wherein the polyimide film according to any one of [1] to [3] is used.
[5] A copper-clad, wherein the polyimide film according to any one of [1] to [4] is used, and the number of pinholes in the copper layer in the laminate is 30/100 cm ² or less. Laminated body.
[6] A COF substrate, wherein the copper clad laminate according to any one of [4] to [5] is used.

  The polyimide film of the present invention can effectively suppress the occurrence of dimensional change in the COF manufacturing process using the semi-additive method. Moreover, the polyimide film of this invention can suppress the thermal expansion coefficient of this direction low by advancing the orientation to TD of a film, and its heat shrinkage rate is also low. Furthermore, the polyimide film of the present invention has a small surface roughness by using a filler having a small average particle diameter. Furthermore, since the copper clad laminate manufactured using the polyimide film of the present invention has few pinholes in the copper layer, it is useful for a substrate for COF.

It is a figure which shows 36 thermal expansion coefficient measurement points of the polyimide film of Example 1 and Comparative Examples 1-3. It is sectional drawing of the copper clad laminated body which used the polyimide film of Example 1 and Comparative Examples 1-3 as a base material. It is a surface view of the board | substrate for dimension evaluation COF which formed the wiring circuit pattern of copper in the polyimide film of Example 1 and Comparative Examples 1-3. It is sectional drawing of the board | substrate for dimension evaluation COF which formed the wiring circuit pattern of copper in the polyimide film of Example 1 and Comparative Examples 1-3. FIG. 5 is a cross-sectional view after glass is crimped to the dimensional evaluation COF substrate described in FIGS. 3 and 4.

The polyimide film of the present invention is a polyimide film used for a chip-on film comprising a copper wiring portion having a pitch of 10 to 40 μm and forming a wiring so that an IC chip can be mounted by a semi-additive method, The polyimide film is composed of paraphenylenediamine as an aromatic diamine component, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as main ingredients. The protrusions on the surface of the polyimide film are formed from inorganic particles having an average particle diameter of 0.01 to 1 μm, and a TMA-50 manufactured by Shimadzu Corporation is used. Measurement range: 50 ˜200 ° C., temperature rising rate: film thermal expansion coefficient α _MD of 2.0 ppm / ° C. in the machine transport direction (MD) measured at 10 ° C./min. In the range of 10.0 ppm / ° C. or less, the coefficient of thermal expansion α _{TD in} the width direction (TD) is in the range of −2.0 ppm / ° C. to 3.5 ppm / ° C., and | α _MD | ≧ | α _TD It satisfies the relationship of | × 2.0.

The thermal expansion coefficient 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. to 10.0 ppm / ° C., and 3.0 ppm / ° C. to 9.5 ppm / ° C. The range of 3.5 ppm / ° C. to 9.0 ppm / ° C. is more preferable, and the range of 4.0 ppm / ° C. to 8.5 ppm / ° C. is particularly preferable.

The thermal expansion coefficient 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. to 3.5 ppm / ° C., and is particularly suitable for COF use. More preferably, the range is from 5 ppm / ° C. to 3.0 ppm / ° C., more preferably from −1.0 ppm / ° C. to 2.5 ppm / ° C., and from −0.5 ppm / ° C. to 2.0 ppm / ° C. A range is particularly preferred. If it is below the above range, the strength (for example, tensile elongation, etc.) is inferior and the resulting film tends to break, which is not preferable. By setting α _TD within the above range and combining with each component of the present invention, for COF, regardless of the partner to which the polyimide film adheres (for example, the partner to which the film adheres is a metal (eg, copper) (Even for glass), it has excellent dimensional stability, so that the influence of dimensional change on the film side when a polyimide film is bonded to a metal or glass can be kept small, and a high-definition COF circuit board can be obtained. It is possible to design.

The measurement conditions of the thermal expansion coefficients α _MD and α _TD in the present invention are TMA-50 manufactured by Shimadzu Corporation, measured at a measurement temperature range of 50 to 200 ° C., and a temperature increase rate of 10 ° C./min. is there.

The polyimide film of the present invention usually satisfies the relationship of | α _MD | ≧ | α _TD | × 2.0 for α _MD and α _TD , preferably | α _MD | ≧ | α _TD | × 2. 5, more preferably | α _MD | ≧ | α _TD | × 2.8, and more preferably | α _MD | ≧ | α _TD | × 3.0 or more. Also, although not particularly limited, those satisfying the relationship of | α _MD | ≦ | α _TD | × 50.0 are preferable, those satisfying the relationship of | α _MD | ≦ | α _TD | × 30.0 are more preferable, It is more preferable to satisfy the relationship of | α _MD | ≦ | α _TD | × 20.0. Conventionally, if the thermal expansion coefficient of the polyimide film and the metal to be bonded (for example, copper) is different, the problem of thermal stress due to the difference in the thermal expansion coefficient is large, and the laminate obtained by bonding the polyimide film and the metal Although dimensional change due to heat has been a problem, when α _MD and α _TD are within the above range and satisfy the relationship of the above formula, when the polyimide film is bonded to a metal (for example, copper), Even if the thermal expansion coefficient of a metal (for example, the thermal expansion coefficient of copper is 17 ppm / ° C.) and the thermal expansion coefficient of a polyimide film are different, the dimensional stability due to heat of the laminate obtained by bonding the polyimide film and the metal is high. It doesn't matter.

  The inorganic particles used in the polyimide film of the present invention are not particularly limited as long as the average particle diameter is 0.01 to 1 μm, and examples thereof include silica particles having an average particle diameter in this range. The average particle diameter is preferably 0.05 to 0.2 μm. Moreover, the measuring method of this average particle diameter is not specifically limited, You may follow the measuring method of any one of the conventionally well-known standard methods. Examples of the measuring method include a method according to JIS Z8830.

  The surface roughness Ra of the polyimide film of the present invention is preferably 10 nm or less, and more preferably 5 nm or less. Further, the surface roughness Rz of the polyimide film of the present invention is preferably 100 nm or less, and more preferably 50 nm or less. The surface roughness is a value measured using the method described in Examples described later.

The water absorption of the polyimide film of the present invention is preferably 3.0% or less, and more preferably 2.8% or less. The water absorption rate is obtained by immersing the polyimide film in distilled water for 48 hours, taking it out, quickly wiping off the water on the surface, cutting out the sample to a size of 5 mm x 15 mm, and then applying the film to Xu Denki. Using a thermogravimetric analyzer TG-50, the temperature was increased to 200 ° C. at a rate of temperature increase of 10 ° C./min, and the weight before heating and the weight after heating were measured. Is the calculated value.
Water absorption (%) = {(weight before heating) − (weight after heating)} / (weight after heating) × 100

  The tear propagation resistance of the polyimide film of the present invention is not particularly limited, but preferably has a tear propagation resistance of 3.0 N / mm or more for both MD and TD from the viewpoint of good running properties of a film with TD orientation. More preferably, 5.0 N / mm or more. The tear propagation resistance is a value measured using a light load tear tester according to the Elmendorf tear method. The measured value shows the resistance when the film is torn, so it shows the difficulty of tearing in consideration of the whole thickness direction, and the larger the value, the harder it is to tear, and the better the running performance .

  The dimensional change rate of the polyimide film of the present invention is preferably less than 0.01%, and more preferably 0.008% or less. The dimensional change rate is a value measured using the method described in Examples described later.

  In producing the polyimide film of the present invention, first, an aromatic diamine component and an acid anhydride component are polymerized in an organic solvent to obtain a polyamic acid solution.

  The polyimide film of the present invention contains paraphenylenediamine as the aromatic diamine component. The aromatic diamine component may contain other than p-phenylenediamine, and specific examples of the aromatic diamine component other than p-phenylenediamine include metaphenylenediamine, benzidine, p-xylylenediamine, 4,4'-diaminodiphenyl ether. 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 3,3′-dimethyl-4,4′-diaminodiphenylmethane, 1,5-diaminonaphthalene, 3, Examples include 3'-dimethoxybenzidine, 1,4-bis (3methyl-5aminophenyl) benzene, and amide-forming derivatives thereof. These may be used individually by 1 type, and 2 or more types may be mixed and used for them. As the aromatic diamine component, a combination of paraphenylenediamine and 4,4'-diaminodiphenyl ether is preferable. In this, the amount of the diamine component of paraphenylenediamine and 4,4′-diaminodiphenyl ether, which has the effect of increasing the tensile modulus of the film, is adjusted, and the resulting polyimide film has a tensile modulus of 6.0 GPa or more. However, it is preferable because the transportability is improved.

  The polyimide film of the present invention contains pyromellitic dianhydride and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride as the acid anhydride component. The acid anhydride component may contain other than pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride and 3,3 ′ Specific examples of the acid anhydride component other than, 4,4′-biphenyltetracarboxylic dianhydride include 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-tetracarboxylic acid and their Aromatic tetracarboxylic anhydride components such as amide-forming derivatives can be mentioned. These may be used individually by 1 type, and 2 or more types may be mixed and used for them.

The blending ratio (molar ratio) of paraphenylenediamine in the aromatic diamine component described above is a wholly aromatic diamine component from the viewpoint of obtaining a thermal expansion coefficient in the above range, giving an appropriate strength to the film, and preventing poor running properties. Among these, at least 31 mol% or more is preferable, 33 mol% or more is more preferable, and 35 mol% or more is more preferable.
The blending ratio (molar ratio) in the acid anhydride component is not particularly limited as long as the effect of the present invention is not hindered, but the content of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is In the total anhydride component, 15 mol% or more is preferable, 20 mol% or more is more preferable, and 25 mol% or more is more preferable.
When a polyimide film is produced from a polyamic acid composed of these aromatic diamine components and acid anhydride components, the thermal expansion coefficient of the polyimide film is within the above range in both the machine transport direction (MD) and the width direction (TD) of the film. 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-dimethylformamide, N, N-diethylformamide and the like. Formamide solvents, N, N-dimethylacetamide, acetamide solvents such as N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, Examples thereof include phenolic solvents such as m- or p-cresol, xylenol, halogenated phenol and catechol, and aprotic polar solvents such as hexamethylphosphoramide and γ-butyrolactone. These may be used alone or in combination of two or more. It is desirable to use as a mixture using And further can be xylene, the use of aromatic hydrocarbons such as toluene.

The polymerization method may be carried out by 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 equivalent to the total amount of the aromatic diamine component (equal mole). In addition to the polymerization method.
(2) A method in which the entire amount of the acid anhydride component is first put in a solvent, and then the aromatic diamine component is added so as to be equivalent to the acid anhydride component for polymerization.
(3) After putting one aromatic diamine component (a1) in a solvent, mixing for the time required for the reaction at a ratio of 95 to 105 mol% of one acid anhydride component (b1) with respect to the reaction component After that, the other aromatic diamine component (a2) is added, and then the other acid anhydride component (b2) is added so that the total aromatic diamine component and the total acid anhydride component are approximately equivalent. A method of adding and polymerizing.
(4) After putting one acid anhydride component (b1) in a solvent, mixing for a time required for the reaction at a ratio of 95 to 105 mol% of one aromatic diamine component (a1) with respect to the reaction component After that, the other acid anhydride component (b2) is added, and then the other aromatic diamine component (a2) is added so that the total aromatic diamine component and the total acid anhydride component are approximately equivalent. And then polymerize.
(5) A polyamic acid solution (A) is prepared by reacting one aromatic diamine component and an acid anhydride component in a solvent so that either one becomes excessive, and the other aromatic diamine component in another solvent. The polyamic acid solution (B) is prepared by reacting either of the acid anhydride component and the acid anhydride component in excess. A method in which the polyamic acid solutions (A) and (B) thus obtained are mixed to complete the polymerization. At this time, when adjusting the polyamic acid solution (A), if the aromatic diamine component is excessive, the polyamic acid solution (B) has excessive acid anhydride component, and the polyamic acid solution (A) has excessive acid anhydride component. In the case of the polyamic acid solution (B), the aromatic diamine component is excessive, the polyamic acid solutions (A) and (B) are mixed, and the total aromatic diamine component and total acid anhydride component used in these reactions are mixed. Adjust so that it is approximately equivalent. The polymerization method is not limited to these, and other known methods may be used.

  The polyamic acid solution thus obtained usually contains 5 to 40% by weight of solid content, and preferably contains 10 to 30% by weight of solid content. The viscosity is usually 10 to 2000 Pa · s as measured with a Brookfield viscometer, and preferably 100 to 1000 Pa · s for stable liquid feeding. Moreover, the polyamic acid in the organic solvent solution may be partially imidized.

  Next, the manufacturing method of a polyimide film is demonstrated. As a method for forming a polyimide film, a polyamic acid solution is cast into a film and thermally decyclized and desolvated to obtain a polyimide film, and a polyamic acid solution is mixed with a cyclization catalyst and a dehydrating agent. The method of obtaining a polyimide film by preparing a gel film by decyclizing it and heating it to remove the solvent is mentioned, but the latter can keep the coefficient of thermal expansion of the resulting polyimide film low. preferable.

  In the method of chemically decyclizing, first, the polyamic acid solution is prepared. In addition, this polyamic acid solution can contain chemically inert organic fillers and inorganic fillers such as titanium oxide, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, and polyimide filler as necessary. The content of the filler is not particularly limited as long as the effect of the present invention is not hindered.

  The polyamic acid solution used here may be a polyamic acid solution polymerized in advance, or may be polymerized sequentially when filler particles are contained.

  The polyamic acid solution may contain a cyclization catalyst (imidization catalyst), a dehydrating agent, a gelation retarder, and the like.

  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 dimethylaniline, and heterocyclic rings such as isoquinoline, pyridine and betapicoline. Although a tertiary amine etc. are mentioned, a heterocyclic tertiary amine is preferable. These may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  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. It does not specifically limit as a gel retarder, Acetyl acetone etc. can be used.

  As a method for producing a polyimide film from a polyamic acid solution, a polyamic acid solution containing the cyclization catalyst and the dehydrating agent is cast from a slit-attached base onto a support, and is molded into a film. Examples of the method include a method in which imidization is partially advanced to form a gel film having self-supporting property, and then peeled from the support, heat-dried / imidized, and heat-treated.

  The support is a metal rotating drum or endless belt, and its temperature is controlled by a liquid or gaseous heat medium and / or by radiant heat from an electric heater or the like.

  The gel film is usually heated to 30 to 200 ° C., preferably 40 to 150 ° C. by receiving heat from the support and / or receiving heat from a heat source such as hot air or an electric heater, and a ring-closing reaction is performed. By drying the volatile matter, it becomes self-supporting and is peeled off from the support.

  Although the gel film peeled from the said support body is not specifically limited, It is preferable to extend | stretch in a conveyance direction, regulating a running speed with a normal rotating roll normally. The stretching in the transport direction is performed at a temperature of 140 ° C. or lower. The draw ratio (MDX) is usually 1.05 to 1.9 times, preferably 1.1 to 1.6 times, and more preferably 1.1 to 1.5 times. The gel film stretched in the conveying direction is introduced into a tenter device, and both ends in the width direction are gripped by the tenter clip, and stretched in the width method while running with the tenter clip. Stretching in the width direction is performed at a temperature of 200 ° C. or higher. The draw ratio (TDX) is usually 1.1 to 1.5 times that of MDX, preferably 1.2 to 1.45 times. By implementing this combination of draw ratios for the gel film obtained by the above blending, a film having the effects of the present invention can be obtained by being oriented in the film TD.

The film dried in the drying zone is heated for 15 seconds to 10 minutes at a temperature of 80 to 300 ° C. with hot air, an infrared heater or the like. Then, hot air and / or electric heater, etc.
Heat treatment is performed at a temperature of ˜500 ° C. for 15 seconds to 20 minutes.

  Moreover, although the running speed is adjusted and the thickness of the polyimide film is adjusted, the thickness of the polyimide film is preferably 3 to 250 μm, and more preferably 5 to 150 μm, in order to prevent deterioration of film forming properties.

  It is preferable to further anneal the polyimide film thus obtained. By doing so, thermal relaxation of the film occurs and the heat shrinkage rate can be kept small. The annealing temperature is not particularly limited, but is preferably 200 ° C. or higher and 500 ° C. or lower, more preferably 200 ° C. or higher and 370 ° C. or lower, and particularly preferably 210 ° C. or higher and 350 ° C. or lower. In the manufacturing method of the polyimide film of the present invention, since the orientation to the film TD is strong, the heat shrinkage rate in this direction tends to be high, but the heat shrinkage rate at 200 ° C. is caused by the thermal relaxation from the annealing treatment. Can be suppressed within the above range, which is preferable because the dimensional accuracy is further improved. Specifically, it is preferable to carry out the annealing treatment by running the film in a furnace heated to the above temperature range under low tension. The time during which the film stays in the furnace is the processing time, but it is controlled by changing the running speed, and the processing time is preferably 30 seconds to 5 minutes. If it is shorter than this, heat is not sufficiently transmitted to the film, and if it is longer, it becomes overheated and the flatness is impaired. The film tension during running is preferably 10 to 50 N / m, more preferably 20 to 30 N / m. When the tension is lower than this range, the running property of the film is deteriorated, and when the tension is high, the heat shrinkage rate in the running direction of the obtained film is increased, which is not preferable.

  Moreover, in order to give adhesiveness to the obtained polyimide film, the surface of the film may be subjected to physical treatment such as electrical treatment such as corona treatment or plasma treatment or blast treatment using a conventional method. The pressure of the atmosphere when performing the plasma treatment is not particularly limited, but is usually in the range of 13.3 to 1330 kPa, preferably in the range of 13.3 to 133 kPa (100 to 1000 Torr), and 80.0 to 120 kPa (600 to The range of 900 Torr is more preferable.

The atmosphere in which the plasma treatment is performed contains at least 20 mol% of inert gas, preferably contains 50 mol% or more of inert gas, more preferably contains 80 mol% or more, and more than 90 mol%. What is contained is most preferable. The inert gas includes He, Ar, Kr, Xe, Ne, Rn, N ₂ and a mixture of two or more thereof. A particularly preferred inert gas is Ar. Furthermore, oxygen, air, carbon monoxide, carbon dioxide, carbon tetrachloride, chloroform, hydrogen, ammonia, tetrafluoromethane (carbon tetrafluoride), trichlorofluoroethane, trifluoromethane, etc. are mixed with the inert gas. May be. Preferred mixed gas combinations used as the plasma treatment atmosphere 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 and the like.

Processing power density when a plasma treatment is not particularly limited, 200 W · min / ^{m 2} or more preferably, 500 W · min / ^{m 2} or more is more preferable, 1000W · min / ^{m 2} or more is most preferred. The plasma irradiation time for performing the 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 accompanying film deterioration. The gas type, gas pressure, and treatment density of the plasma treatment are not limited to the above conditions, and may be performed in the atmosphere.

  Thus, the polyimide film obtained can advance the orientation to TD of a film, can suppress the thermal expansion coefficient of this direction low, and also has a low heat shrinkage rate. Further, since the surface roughness is small by containing a filler having a small average particle diameter, it is suitable for a fine pitch circuit substrate, particularly for COF using a semi-additive method in which wiring is made narrowly on the TD of a film.

  The present invention also includes a copper clad laminate in which the above-described polyimide film of the present invention is used. The manufacturing method of the copper clad laminated body of this invention is not specifically limited, You may follow a conventionally well-known manufacturing method. For example, a method of laminating a layer mainly composed of copper by electroplating on a metal layer mainly composed of nickel and chromium formed by vacuum deposition or sputtering on one or both sides of a polyimide film is used. be able to. The copper clad laminate of the present invention can be obtained, for example, by using the above-described polyimide film of the present invention as a base material and forming copper having a thickness of 1 to 10 μm thereon according to a conventional method.

Number of pin holes of the copper layer in the copper-clad laminate of the present invention is preferably from 30/100 cm ² or less, more preferably 20/100 cm ² or less, more preferably 10 pieces / 100 cm ² or less. In addition, the number of pinholes is a value measured using a method described in Examples described later.

The present invention also includes a COF substrate in which the above-described copper-clad laminate of the present invention is used.
The method for producing a substrate for COF of the present invention is not particularly limited as long as it is a method using a semi-additive method, and a known method can be used.
As a semi-additive method used in the present invention, for example, first, a metal (copper) layer serving as a seed layer is formed directly on the polyimide film of the present invention or via an adhesive, and a photo layer is formed on the seed layer. A resist layer is formed, the photoresist layer is selectively exposed and developed to be patterned into a wiring shape, and a wiring is formed on the seed layer by electroless plating or electrolytic plating using the patterned photoresist layer as a plating mask. Thereafter, the copper-clad laminate of the present invention can be obtained by a method in which the photoresist is completely removed and finally the seed layer other than the wiring is etched away. For example, a liquid or dry film resist is used as the photoresist. In the COF substrate of the present invention, the copper wiring portion is usually at a pitch of 10 to 40 μm. Further, the COF substrate of the present invention has wiring formed so that an IC chip can be mounted.

  The present invention includes embodiments in which the above-described configurations are variously combined within the technical scope of the present invention as long as the effects of the present invention are exhibited.

[Example]
EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples at all, and many variations are within the technical idea of the present invention. This is possible by those with ordinary knowledge.

  In the examples, PPD represents paraphenylenediamine, 4,4′-ODA represents 4,4′-diaminodiphenyl ether, PMDA represents pyromellitic dianhydride, and BPDA represents 3,3 ′, 4. , 4′-diphenyltetracarboxylic dianhydride, DMAc represents N, N-dimethylacetamide, respectively.

Moreover, each characteristic in an Example was evaluated with the following method.
(1) Coefficient of thermal expansion Equipment: TMA-50 (trade name, manufactured by Shimadzu Corporation) was used, and measurement was performed under the conditions of measurement temperature range: 50 to 200 ° C., temperature increase rate: 10 ° C./min. The coefficient of thermal expansion is 12 points including 2 points 7 mm inside from the same position in the film transport direction and 7 mm from both ends of the film, and 10 points taken at equal intervals on a straight line between the two points, and 12 points. Measurement samples were collected from a total of 36 points, 12 points at regular intervals taken at a position 50 mm away from the measurement point in the film transport direction and 12 points equally spaced at positions 50 mm apart. The average value of 36 points (FIG. 1).

(2) Variation in thermal expansion coefficient (CTE) The standard deviation (σ) of the 36-point TD thermal expansion coefficient measured as described above was calculated and used as the TD thermal expansion coefficient (CTE) variation.

(3) Surface observation of film After shadowing Ag on the film at a shadowing angle of 5 ° and sputter-coating Pt, the surface is observed using a scanning electron microscope (SEM) S5000 (trade name, manufactured by Hitachi, Ltd.) Then, the average particle diameter of the filler particles (silica particles or calcium hydrogen phosphate particles) on the film surface was measured. In addition, this measurement calculates | requires the average particle diameter of the filler particle in the state disperse | distributed in the film. In a polyimide film prepared using silica particles having an average particle diameter of 0.1 μm, when the average particle diameter of the silica particles on the film surface calculated using this measurement method is 0.1 μm, that is, dispersion in the polyimide film When the average particle diameter of the silica particles is not different between before and after, it indicates that the silica particles are uniformly dispersed in the polyimide film.
In addition, the average particle diameter of Table 1 shows the average particle diameter of the silica particle or calcium hydrogenphosphate particle before adding to a film.

(4) OLB (outer lead bonding) variation (dimensional change)
A 0.025 μm thick nickel chromium alloy layer (nickel 80%, chromium 20%) and a 10 μm thick copper layer were formed on one side of the polyimide film by sputtering and plating to prepare a copper clad laminate sample (FIG. 2). Further, the copper layer was etched, and an evaluation circuit pattern having a line width of 15 μm and a space width of 15 μm was provided to obtain a COF substrate for dimension evaluation (FIG. 3 shows a surface view of the COF substrate, and FIG. 4 shows the COF substrate). Shows a cross-sectional view of the substrate.
This is pressure-bonded to an adherend (glass) using an anisotropic conductive film (ACF: product name, Anisolum C5311 manufactured by Hitachi Chemical Co., Ltd.) under conditions of 180 ° C. × 10 seconds and 5 MPa (FIG. 5). After measuring the external dimensions of the circuit pattern for evaluation of the substrate 30 sample for the glass before (L1) and after the pressure bonding (L2) of the glass, the standard deviation (σ) of the elongation calculated by the following formula is calculated, We asked for OLB variation. In the present invention, the dimensional change rate is the elongation rate.
Elongation rate (%) = {(L2-L1) / L1} × 100

(5) Surface roughness The surface roughness of the film was measured using a laser microscope (trade name, VK-9710, manufactured by KEYENCE). Surface roughness analysis was performed using analysis software (trade name, VK Analyzer, manufactured by KEYENCE) to determine the surface roughness Ra and Rz of the film.

(6) Pinhole After a 30 nm Ni / Cr layer is formed on the film surface by sputtering, a 120 nm Cu layer is formed by sputtering, and then a 2 μm Cu layer is formed by electrolytic plating. After producing (copper-clad laminate), pinholes were visually counted in the range of 10 × 10 cm. The pinhole was a CCL transmission portion as viewed from the upper surface of the copper layer, with the CCL placed on the backlight with the CCL copper layer facing upward. In Table 1, which will be described later, D means a drum surface (a surface in contact with a polyimide film as a support), and A means an air surface (a surface opposite to the polyimide film as a support).

[Synthesis Example 1]
In a 500 ml separable flask, 238.6 g of DMAc was placed, and 5.68 g (0.053 mol) of PPD, 19.52 g (0.098 mol) of 4,4′-ODA, 11.03 g (0.038 mol) of BPDA, PMDA24 .54 g (0.113 mol) was added, reacted at room temperature and normal pressure for 1 hour, and stirred until uniform to obtain a polyamic acid solution.

[Example 1]
A slurry obtained by dispersing silica particles having an average particle size of 0.1 μm in DMAc in the polyamic acid solution prepared in Synthesis Example 1 is added so that the weight of the silica particles is 0.6% by weight based on the weight of the polyamic acid resin. After sufficiently stirring and dispersing, 15 g of this polyamic acid solution was taken, cooled at minus 5 ° C., and then mixed with 1.9 g of acetic anhydride and 1.8 g of β-picoline to obtain a mixed solution. Then, after casting for 30 seconds on a rotating drum at 90 ° C., the obtained gel film was heated at 100 ° C. for 5 minutes, then heated at 380 ° C. for 5 minutes, and TD: 250 mm, MD: 250 mm, 38 μm thick The polyimide film was obtained. The polyimide film was annealed for 1 minute in a furnace set at 220 ° C. with a tension of 20 N / m, and each physical property was evaluated as shown in Table 1. In addition, it confirmed that the silica particle was disperse | distributed uniformly in the obtained polyimide film by the surface observation method of an above-described film. Further, in Table 1, CTE variation means variation in coefficient of thermal expansion (CTE) of TD.

[Synthesis Example 2]
Into a 500 ml separable flask was placed 238.6 g of DMAc, and 2.76 g (0.026 mol) of PPD, 23.29 g (0.116 mol) of 4,4′-ODA, 14.60 g (0.050 mol) of BPDA, PMDA20 .11 g (0.092 mol) was added, reacted at room temperature and normal pressure for 1 hour, and stirred until uniform to obtain a polyamic acid solution.

[Comparative Example 1]
After 0.15% by weight of a slurry of calcium hydrogen phosphate having an average particle size of 1.0 μm dispersed in DMAc was added to the polyamic acid solution prepared in Synthesis Example 2 per resin weight, and sufficiently stirred and dispersed, After taking 15 g from the polyamic acid solution and cooling at minus 5 ° C., 1.9 g of acetic anhydride and 1.8 g of β-picoline were mixed to obtain a mixed solution, which was then placed on a rotating drum at 90 ° C. for 30 seconds. After casting, the obtained gel film was heated at 100 ° C. for 5 minutes and then heated at 380 ° C. for 5 minutes to obtain a polyimide film having a thickness of TD: 250 mm and MD: 250 mm and a thickness of 38 μm. The polyimide film was annealed for 1 minute in a furnace set at 220 ° C. with a tension of 20 N / m, and each physical property was evaluated as shown in Table 1. In addition, it was confirmed by the above-described film surface observation method that the calcium hydrogen phosphate particles were uniformly dispersed in the obtained polyimide film.

[Comparative Example 2]
After adding 0.4% by weight of a slurry of silica particles having an average particle diameter of 0.4 μm dispersed in DMAc to the polyamic acid solution prepared in Synthesis Example 2 per weight of resin, and sufficiently stirring and dispersing, the polyamic acid After taking 15 g from the solution and cooling at minus 5 ° C., 1.9 g of acetic anhydride and 1.8 g of β-picoline were mixed to obtain a mixed solution, which was then cast on a rotating drum at 90 ° C. for 30 seconds. Then, the obtained gel film was heated at 100 ° C. for 5 minutes, and then heated at 380 ° C. for 5 minutes to obtain a polyimide film having a thickness of TD: 250 mm and MD: 250 mm and a thickness of 38 μm. The polyimide film was annealed for 1 minute in a furnace set at 220 ° C. with a tension of 20 N / m, and each physical property was evaluated as shown in Table 1. In addition, it confirmed that the silica particle was disperse | distributed uniformly in the obtained polyimide film by the surface observation method of an above-described film.

[Synthesis Example 3]
Into a 500 ml separable flask was placed 238.6 g of DMAc, and 4.64 g (0.043 mol) of PPD, 21.04 g (0.105 mol) of 4,4′-ODA, 10.89 g (0.037 mol) of BPDA, PMDA24 .21 g (0.111 mol) was added, reacted at room temperature and normal pressure for 1 hour, and stirred until uniform to obtain a polyamic acid solution.

[Comparative Example 3]
After adding 0.4% by weight of a slurry of silica particles having an average particle diameter of 0.4 μm dispersed in DMAc to the polyamic acid solution prepared in Synthesis Example 3 per weight of the resin, and thoroughly stirring and dispersing, the polyamic acid After taking 15 g from the solution and cooling at minus 5 ° C., 1.9 g of acetic anhydride and 1.8 g of β-picoline were mixed to obtain a mixed solution, which was then cast on a rotating drum at 90 ° C. for 30 seconds. Then, the obtained gel film was heated at 100 ° C. for 5 minutes, and then heated at 380 ° C. for 5 minutes to obtain a polyimide film having a thickness of TD: 250 mm and MD: 250 mm and a thickness of 38 μm. The polyimide film was annealed for 1 minute in a furnace set at 220 ° C. with a tension of 20 N / m, and each physical property was evaluated as shown in Table 1. In addition, it confirmed that the silica particle was disperse | distributed uniformly in the obtained polyimide film by the surface observation method of an above-described film.

As shown in Table 1 above, the polyimide film of the present invention of Example 1 has a low coefficient of thermal expansion of TD, a small variation in coefficient of thermal expansion of TD, excellent dimensional stability, and was produced using the polyimide film. Since the copper-clad laminate has few pinholes and the film surface is smooth, it is useful in fine pitch circuit substrates, particularly in COF applications by a semi-additive method in which wiring is made narrowly on the TD of the film.
On the other hand, the polyimide films of Comparative Examples 1 to 3 have a large TD thermal expansion coefficient, a large variation in the thermal expansion coefficient of TD, poor dimensional stability, and the copper clad laminate produced using the polyimide film is a pin Since there are many holes and the film surface is not smooth, it is not useful in fine pitch circuit substrates, particularly in COF applications by the semi-additive method in which wiring is performed at a narrow pitch on the TD of the film.

  The polyimide film of the present invention can effectively suppress the occurrence of dimensional changes in the COF manufacturing process, has a low heat shrinkage rate, and has a small surface roughness. It can be suitably used for the COF application by the semi-additive method in which wiring is made to TD with a narrow pitch.

Claims (6)

A polyimide film used for a chip-on film comprising a copper wiring portion having a pitch of 10 to 40 μm by a semi-additive method and formed with a wiring so that an IC chip can be mounted, wherein the polyimide film is an aromatic diamine It is composed of paraphenylenediamine as a component, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as an acid anhydride component as main raw materials, And the processus | protrusion on this polyimide film surface is formed from the inorganic particle whose average particle diameter is 0.01-1 micrometer, and uses TMA-50 made by Shimadzu Corporation, measurement range: 50-200 degreeC, temperature increase rate : The coefficient of thermal expansion 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. to 10.0 ppm / ° C. Yes, thermal expansion coefficient α _TD in the width direction (TD) is in the range of −2.0 ppm / ° C. to 3.5 ppm / ° C., and satisfies the relationship of | α _MD | ≧ | α _TD | × 2.0 Polyimide film characterized by   The polyimide film according to claim 1, wherein the paraphenylenediamine is at least 31 mol% or more in the wholly aromatic diamine component.   3. The polyimide film according to claim 1, wherein the surface roughness Ra and Rz of the film are in the range of 10 nm or less and 100 nm or less, respectively.   A copper-clad laminate in which the polyimide film according to any one of claims 1 to 3 is used. The polyimide film of any one of Claims 1-4 is used, The number of pinholes of the copper layer in a laminated body is 30 pieces / 100 cm < ² > or less, The copper clad laminated body characterized by the above-mentioned.   A substrate for COF, wherein the copper clad laminate according to any one of claims 4 to 5 is used.