JP2004331788A - Polyimide film and metal wiring board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide film which, when applied for a metal wiring board substrate for a flexible printed circuit, CSP, BGA or TAB tape the surface of which is provided with a metal wiring, shows high elastic modulus, a low coefficient of thermal expansion, excellent alkali etching property and film formability; to provide its manufacturing method; and to provide a metal wiring circuit board comprising it as a substrate. <P>SOLUTION: The polyimide film, obtained from a polyamic acid using 3,4'-oxydianiline as the diamine component, has a number of times of folding endurance (MIT) of ≥20,000 and a coefficient of linear expansion (CTE) of 13-22 ppm/°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００９８】
【表２】

【００９９】
【表３】

【０１００】
表１、表２に記載されている結果を比較して明らかなように、ＰＭＤＡ、３，４’−ＯＤＡ、４，４’−ＯＤＡからなる本発明のブロックポリイミドフィルムは、共重合フィルムに比較して、耐折回数及び線膨張係数が著しく改善しており、ＦＰＣ、ＣＳＰ、ＢＧＡ、またはＴＡＢテープ用金属配線基板としての好適な性能を有する物である。
【０１０１】
表１、表３に記載されている結果を比較して明らかなように、ＰＭＤＡ、３，４’−ＯＤＡ，４，４’−ＯＤＡからなる本発明の３，４’−ＯＤＡとＰＭＤＡブロックを末端封止したポリイミドフィルムは、３，４’−ＯＤＡとＰＭＤＡを末端封止しないブロックフィルムに比較して、耐折回数及び線膨張係数が著しく改善しており、ＦＰＣ、ＣＳＰ、ＢＧＡ、またはＴＡＢテープ用金属配線基板としての好適な性能を有するものである。
【０１０２】
【発明の効果】
以上説明したように、本発明のポリイミドフィルムは、共重合で得られたポリイミドフィルムに比しても、可撓性ＦＰＣ、用金属配線基板として適用した場合に、優れた耐折回数、寸法安定性、アルカリエッチング性を有するものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention has a high elasticity when used as a metal printed wiring board for a flexible printed circuit or a tape automated bonding (Tape Automated Bonding) tape (hereinafter referred to as a TAB tape). TECHNICAL FIELD The present invention relates to a polyimide film excellent in modulus, low linear expansion coefficient, alkali etching property, and film forming property, a method for producing the same, and a metal wiring board for a flexible printed circuit or TAB tape using the polyimide film as a base material.
[0002]
[Prior art]
The TAB tape is provided with ultra-fine metal wiring on the surface of the heat-resistant film as a base material, and has "windows" opened for mounting an integrated circuit chip (IC) on the base material. A sprocket for feeding the TAB tape precisely is provided in the vicinity.
[0003]
The TAB tape inserts the IC into the "window" opened in the TAB tape and joins it with the metal wiring provided on the surface of the TAB tape. Then, the TAB tape with the IC is mounted on a printed circuit for electronic device wiring. Bonding is used to automate the process of mounting an IC on an electronic circuit, simplify the process, improve productivity, and improve the electrical characteristics of an electronic device on which the IC is mounted.
[0004]
The TAB tape has a three-layer structure in which a conductive metal foil is laminated on the surface of a heat-resistant base film via an adhesive such as a polyester base, an acrylic base, an epoxy base, or a polyimide base; One having a two-layer structure in which a conductive metal layer is directly laminated on the surface of a heat-resistant base film without using an adhesive is used.
[0005]
Therefore, the base film of the TAB tape is required to have heat resistance, particularly when joining the IC to the metal wiring on the TAB tape or joining the IC mounted TAB tape to the printed circuit for electronic device wiring. Conventionally, a polyimide film has been used so as to withstand high temperatures such as solder welding applied to a base film.
[0006]
However, when a polyimide film and a metal foil or a metal layer are laminated, and the metal foil or the metal layer is chemically etched to form a metal wiring, TAB caused by a difference in dimensional change between the polyimide film and the metal due to the heat received. When the deformation of the tape is large, workability may be significantly impaired or sometimes impossible when mounting an IC or bonding a TAB tape mounting an IC to a printed circuit for wiring electronic equipment. Therefore, it is required that the coefficient of thermal expansion of the polyimide film be approximated to that of metal to reduce the deformation of the TAB tape.
[0007]
Furthermore, it is possible to reduce the dimensional change due to the tensile force and the compressive force applied to the TAB tape which is mounted on the printed circuit for wiring the electronic device by mounting the IC, to reduce the size of the metal wiring, reduce the strain load on the metal wiring, and This is important for reducing the strain load of the mounted IC, and a polyimide film as a base material is required to have a higher elastic modulus.
[0008]
Definition of polymer alloy or polymer blend ("New perspectives and practical application of polymer alloy: High value-added series of polymer", supervision; Saburo Akiyama, Shinichi Izawa, publishing; CMC Co., Ltd., publication year; April, 1997) ), It is said that the increase in the elastic modulus of a polymer includes, for example, block, blend, intermixing (IPN, interpenetrating-polymer-network), and graft polymerization.
[0009]
In particular, with regard to increasing the elastic modulus of polyimide, Mita et al. (J. Polym. Sci., Part C: Polym. Lett., 26 (5), 215-223) use the same raw material due to the molecular composite effect. Has proposed that a blend of polyimides is more likely to have a higher elastic modulus than a polyimide. However, since polyimide molecules have a large molecular cohesive force, a simple blend tends to have a phase-separated structure. Therefore, some physical bonding is required to suppress phase separation.
[0010]
The polymer proposed for that purpose is described by Yui et al. ("Design and Future Prospects of Functional Supramolecules: New Materials and New Materials Series", supervision; Naoya Ogata, Minoru Terano, Nobuhiko Yui, Publishing; CMC Corporation) (Published year: June 1998) by Interpenetrating-network-polymer (hereinafter referred to as mixed polymer).
[0011]
Specific examples of the conventional mixing include a polyamic acid composition (C) of a polyamic acid (A) with pyromellitic acid and 4,4′-diaminodiphenyl ether and a polyamic acid (B) with pyromellitic acid and phenylenediamine. ) Has been proposed (for example, see Patent Document 1). Further, a polyimide produced from the polyamic acid composition (C) has been proposed (for example, see Patent Document 1).
[0012]
However, in these conventional mixing methods, since the polyamic acid is polymerized in advance and then mixed, sufficient physical entanglement (mixing) cannot be performed, so that phase separation may occur at the stage of imidizing the polyamic acid. There was a problem that only a slightly cloudy polyimide film could be obtained.
[0013]
Further, a block polyimide film produced from a block polyamic acid composed of pyromellitic dianhydride, paraphenylenediamine and 4,4′-diaminodiphenyl ether has been proposed. There has been proposed a method of producing a block component polyamic acid film having an equimolar composition by reacting in an equivalent amount (for example, see Patent Documents 2 to 5).
[0014]
However, in these conventional methods, although the polyamic acid blend solution is unlikely to cause phase separation, the molecular composite effect is insufficient and the high rigidity may not be satisfactory. In addition, in order to produce a polymer having a block component whose molecular chain is controlled as a copolymer component, the reaction step becomes complicated, the reaction time becomes long, and a step in which reactive terminals are excessively present is required. Therefore, the polyamic acid in the middle of the process is unstable and easily changes in viscosity, and there is a problem in production such as gelation. In addition, there were cases where this method was insufficient to increase the Young's modulus. In addition, in order to improve the adhesive strength of the adhesive, the surface of the polyimide film as a base material may be roughened by etching with an alkali solution. In some cases, holes (through holes) for wiring are formed by alkali etching. For this reason, a demand for a polyimide film having excellent alkali etching properties is increasing.
[0015]
In addition, the flatness of the film is improved by increasing the stretching ratio during film formation. For this reason, a film composition that can be stretched at a high magnification is desired.
[0016]
Conventional methods aimed at obtaining a polyimide film satisfying these required properties include pyromellitic dianhydride, a polyamic acid composed of para 4,4′-oxydianiline and 44′-diaminodiphenyl ether. Produced polyimide films have been proposed, and methods for producing a block component polyamic acid film by reacting a diamine and an acid dianhydride in non-equivalent amounts in a further intermediate step have been proposed (for example, Patent Documents 2 to 3 and Patent Document 5).
[0017]
However, in the above-mentioned conventional method, when used as a metal wiring board base material, a polyimide film which simultaneously satisfies a high elastic modulus, a low coefficient of linear expansion, an alkali etching property, and a film-forming property cannot be obtained. Was required.
[0018]
[Patent Document 1]
JP-A-63-175025
[Patent Document 2]
JP-A-1-131241
[Patent Document 3]
JP-A-1-131242
[Patent Document 4]
U.S. Pat. No. 5,081,229
[Patent Document 5]
JP-A-3-46292
[0019]
[Problems to be solved by the invention]
The present invention has been achieved as a result of examining the solution of the problems in the prior art described above as a problem, and has been achieved by using a flexible printed circuit having a metal wiring on the surface thereof, a CSP, a BGA or a TAB tape. Provided is a polyimide film excellent in a high elastic modulus, a low coefficient of linear expansion, an alkali etching property, and a film-forming property when applied to a metal wiring board base material, a method for manufacturing the same, and a metal wiring circuit board using the same as a base material. It is intended to do so.
[0020]
[Means for Solving the Problems]
In order to achieve the above object, the polyimide film of the present invention is a polyimide film obtained from poarimidic acid using 3,4′-oxydianiline as a diamine component, and has a fold resistance (MIT) of 20,000 or more. And a linear expansion coefficient (CTE) of 13 ppm / ° C to 22 ppm / ° C.
[0021]
In addition, the polyimide film of the present invention comprises 10 to 90 mol% of 4,4'-oxydianiline and 10 to 90 mol% of 3,4'-oxydiamine based on pyromellitic dianhydride and diamine. It is produced from a polyamic acid having a block component composed of aniline or a mixed polymer component. In this case, 30 to 70 mol% of 4,4′-based on pyromellitic dianhydride and diamine. More preferably, it is prepared from a polyamic acid having a block component or a mixed polymer component consisting of oxydianiline and 30-70 mol% of 3,4'-oxydianiline.
[0022]
In addition, the polyimide film of the present invention contains 4,4′-oxydianiline in an amount of more than 20 mol% to 80 mol% or less based on pyromellitic dianhydride and diamine, and more than 20 mol% to 80 mol% or less. It is preferably characterized by being produced from a polyamic acid consisting of 3,4'-oxydianiline.
[0023]
In addition, the polyimide film of the present invention can be obtained by combining a general method for producing polyimide. A preferable production method for easily obtaining the present invention comprises the following steps (A) to (E). It is preferable that the process is performed sequentially.
[0024]
(A) Pyromellitic dianhydride, 4,4'-oxydianiline and 3,4'-oxydianiline are prepared by adding 3,4'-oxydianiline and pyromellitic dianhydride in an inert solvent. Reacting using at least 1 to 99% by weight of the amount of pyromellitic dianhydride or all diamines used to form a polyamic acid having a block component or a mixed polymer component with the product,
(B) a step of additionally using the remaining raw materials in the polyamic acid polymer from the step (A), and finally reacting using the total amount of the total amount used;
(C) mixing the polyamic acid solution from the step (B) with a conversion agent capable of converting the polyamic acid into a polyimide;
(D) casting or extruding the mixture from step (C) onto a smooth surface to form a polyamic acid-polyimide gel film; and
(E) a step of heating the gel film from the step (D) at a temperature of 200 to 500 ° C. to convert the polyamic acid to a polyimide.
[0025]
In the method for producing a polyimide film of the present invention, the polyamic acid is 10 to 90 mol% of 4,4′-oxydianiline and 10 to 90 mol% based on pyromellitic dianhydride and diamine. A polyamic acid having a block component or a mixed polymer component composed of 3,4′-oxydianiline, and a flexible printed circuit or a metal wiring board for TAB of the present invention comprises the above polyimide film. The substrate is characterized in that metal wiring is provided on the surface thereof.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration and effects of the present invention will be described in detail.
[0027]
The polyimide constituting the film of the present invention may be either a block polymer, a random polymer, or a mixed polymer.
[0028]
Preferred block components or mixed polymers are polyamic acids consisting of 4,4'-oxydianiline and pyromellitic dianhydride or polyamic acids consisting of 3,4'-oxydianiline and pyromellitic dianhydride. A polyamic acid containing these block components or mixed polymer components is formed and then imidized to obtain a polyimide containing a block component or mixed polymer components.
[0029]
The reaction to form the polyamic acid is performed at least in two parts, and the polyamic acid containing the block component or the mixed polymer component or the mixed polymer component is formed and incorporated into the polyimide polymer by imidization.
[0030]
The polyimide polymer of the present invention has a high elastic modulus, a low coefficient of linear expansion, and an alkali-etching property when applied to a flexible printed circuit, a metal wiring board substrate for CSP, BGA or TAB tape. It is possible to realize a polyimide film that is highly satisfied by balancing film forming properties.
[0031]
By incorporating a block component or a mixed polymer component into the polyimide polymer, the above properties can be set in more preferable ranges. Particularly preferred block components or mixed polymer components in this case are those obtained by reaction with 3,4'-oxydianiline and pyromellitic dianhydride.
[0032]
Diamines used in the present invention include inflexible diamines such as 4,4'-oxydianiline and linear diamines such as 3,4'-oxydianiline. Other diamines can be used in combination within a range of an addition amount that does not inhibit the object of the present invention.
[0033]
When the polymer has a block component or a mixed polymer component, the polyimide is about 10 to 90 mole%, preferably 30 to 70 mole%, of 4,4'-oxydianiline or 3,4 ', based on the total moles of diamine. It is produced by imid conversion of a polyamic acid obtained using oxydianiline.
[0034]
When a random polymer, the polyimide is a polyamic acid obtained by using 4,4′-oxydianiline or 3,4′-oxydianiline in an amount of more than 20 mol% to 80 mol% or less based on the total amount of diamine. Is produced by imid conversion.
[0035]
In the present invention, 4,4'-oxydianiline acts to increase the flexibility of the film.
[0036]
In the present invention, 3,4′-oxydianiline acts to increase the elongation of the film and improve the film forming property. In the case of a polymer having a block component or a mixed polymer component, if the content of 3,4′-oxydianiline is less than 10 mol%, the elongation of the film becomes small, the film-forming property may be deteriorated, or the rigidity may be insufficient. Conversely, if the content of 3,4′-oxydianiline exceeds 90 mol%, the glass transition temperature (Tg) becomes low, so that the heat shrinkage becomes too large and the heat resistance becomes poor.
[0037]
In the case of a random polymer, if the content of 3,4′-oxydianiline is 20 mol% or less, the elongation of the film becomes small, and the film-forming property may be deteriorated or the rigidity may be insufficient. Conversely, if the content of 3,4′-oxydianiline exceeds 80 mol%, the heat shrinkage becomes too large, and the heat resistance becomes poor.
[0038]
The tetracarboxylic dianhydride used in the present invention is pyromellitic dianhydride, but tetracarboxylic dianhydride and the like can be used in combination within a range of an addition amount that does not inhibit the object of the present invention. For example, less than 50 mol% of biphenyltetracarboxylic dianhydride or benzophenonetetracarboxylic dianhydride can be added. It is produced by imid conversion of the obtained polyamic acid.
[0039]
The modulus of elasticity of the polyimide film can be adjusted by the use ratio of the 3,4′-oxydianiline component in the diamine component used in producing the polyamic acid. When a large amount of the 3,4'-oxydianiline component is used, high elastic modulus and dimensional stability are improved, but heat resistance is disadvantageously reduced. Therefore, it is necessary to carefully adjust the molar ratio of each component in order to balance each characteristic value.
[0040]
The polyamic acid of the present invention is prepared by mixing the above-mentioned tetracarboxylic dianhydride component and diamine component at a temperature of about 175 ° C. or lower, preferably 90 ° C. or lower, with a molar ratio of about 0.90 to 1.10, preferably 0.95 To 1.05, more preferably 0.98 to 1.02, and is produced by reacting each component with a non-reactive organic solvent.
[0041]
Each of the above components may be independently supplied sequentially into the organic solvent, or may be supplied simultaneously, or the organic solvent may be supplied to the mixed components, but in order to perform a uniform reaction. Is preferably added sequentially to the organic solvent.
[0042]
When the respective components are sequentially supplied, it is preferable to supply the diamine component and the tetracarboxylic dianhydride component, which are the block components or the mixed polymer components, with priority. That is, in order to produce a polyamic acid containing a block component or a mixed polymer component, the reaction is carried out at least twice, and first, a polyamic acid containing a block component or a mixed polymer component is obtained. Is converted into a imide, whereby a block component or a mixed polymer component is incorporated into the obtained polyimide.
[0043]
The time required to form the polyamic acid block component or mixed polymer component may be determined by the reaction temperature and the ratio of the block component or mixed polymer component in the polyamic acid, and empirically is from about 1 minute to about 20 minutes. Time is appropriate.
[0044]
At this time, as described later, in order to form a polymer containing a block component, the diamine component and the tetracarboxylic dianhydride component to be reacted in the reaction step (A) are substantially non-equimolar. In order to form a mixed polymer component, the diamine component and the tetracarboxylic dianhydride component in the reaction step (A) must be substantially equimolar, or if the reaction step involves an excess of diamine, then It is preferable to block the terminal with an acid anhydride. The fact that the diamine component and the tetracarboxylic dianhydride component are substantially equimolar, or that the terminal is blocked with a dicarboxylic anhydride in the reaction step in which the diamine is excessive, is a block component formed in these reaction steps. Alternatively, it means that the mixed polymer component is chemically inert and will not be incorporated into the terminal of the polyimide polymer formed in the subsequent reaction. However, since the reaction of the block component or the mixed polymer component and the subsequent reaction of forming the polyimide are performed in the same reaction tank, a molecular composite (composite of different molecules) is easily formed, and the block component or the mixed polymer is mixed. The characteristics of the polymer component can be further exhibited.
[0045]
Specifically, pyromellitic dianhydride (PMDA) is used as a tetracarboxylic dianhydride component, and 4,4′-oxydianiline (44′ODA) and 3,4′-oxydianiline (34) are used as diamine components. An example of the production of a polyimide polymer containing a block component or a mixed polymer component consisting of PMDA and 34 'ODA using' ODA) will be described below.
[0046]
First, 34 ′ ODA is dissolved in dimethylacetamide (DMAc) as an organic solvent, and PMDA is added to complete the reaction of the block component or the mixed polymer component. Then, after adding 44 ′ ODA to the solution and dissolving it, PMDA is added to the solution and reacted to obtain a three-component polyamic acid solution containing a block component or a mixed polymer component of 34 ′ ODA and PMDA.
[0047]
In this case, a small amount of 34 'ODA is added to the PDA supplied first, or the molar ratio of PDA and PMDA to be reacted first is made unequal, and the terminal amount of PDA to be sufficiently reacted with the excess diamine component is sufficient. It is possible to control the size of the block component or the mixed polymer component by adding a sealant. However, in order to make the effect of the block component or the mixed polymer component effective, 34 ′ ODA and PMDA It is preferable to use a mixed polymer in which the molar ratio of the above is substantially equal.
[0048]
The terminal capping agent to be used can also be preferably added with a terminal capping agent such as dicarboxylic anhydride or silylating agent in a range of 0.001 to 2% based on the solid content (polymer concentration). Acetic anhydride or phthalic anhydride is preferably used as the dicarboxylic anhydride, and non-halogen hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N-bis (trimethylsilyl) urea is particularly preferably used as the silylating agent. .
[0049]
The end point of the production of polyamic acid is determined by the polyamic acid concentration of the solution and the viscosity of the solution. In order to accurately determine the viscosity of the solution at the end point, it is effective to add a part of the finally supplied component as a solution of an organic solvent used in the reaction, but it does not significantly reduce the polyamic acid concentration. Such adjustment is necessary.
[0050]
The polyamic acid concentration in the solution is 5 to 40% by weight, preferably 10 to 30% by weight.
[0051]
The organic solvent is preferably selected from those which are non-reactive with the respective components and the polyamic acid which is a polymerization product, are capable of dissolving all of one of the components, and dissolve the polyamic acid.
[0052]
Desirable organic solvents include N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methyl-2-pyrrolidone and the like. Alternatively, they can be used in combination, and in some cases, can be used in combination with a poor solvent such as benzene.
[0053]
In producing the polyimide film of the present invention, the polyamic acid solution thus obtained is pressurized by an extruder or a gear pump and sent to a polyamic acid film production step.
[0054]
The polyamic acid solution is mixed with the raw material, or is filtered to remove foreign matters, solids, high-viscosity impurities, and the like generated in the polymerization process, and is formed into a film through a die for forming a film or a coating head, Extruded onto a rotating or moving support and heated from the support to produce a polyamic acid-polyimide gel film in which the polyamic acid is partially imidized, this gel film becomes self-supporting and can be peeled from the support The polyimide film is peeled off from the support at the time of the introduction, introduced into a drier, heated by the drier, and the solvent is dried to complete the imide conversion, whereby a polyimide film is produced.
[0055]
At this time, the use of a 20 μm-cut metal fiber sintered filter is effective for removing the gel formed on the way. More preferably, it is a 10 μm cut metal fiber sintered filter, and most preferably, it is a 1 μm cut metal fiber sintered filter.
[0056]
Either a thermal conversion method by heating alone, a chemical conversion method in which a polyamic acid mixed with an imidizing agent is heat-treated, or a polyamic acid is immersed in a bath of an imidizing agent is adopted as a method for imide conversion of polyamic acid. However, in the present invention, when the chemical conversion method is applied to a metal substrate for a flexible printed circuit, a CSP, a BGA or a TAB tape, the chemical conversion method is higher than the thermal conversion method. It is suitable for achieving a high degree of balance by balancing the elastic modulus, low coefficient of thermal expansion, alkali etching property and film forming property.
[0057]
In addition, the method of mixing the imidizing agent with the polyamic acid by the chemical conversion method and forming a film and then performing a heat treatment is advantageous in that the time required for the imidizing conversion is short and the imidizing can be performed uniformly. It is easy to peel off, furthermore, it has an advantage such as strong odor and the ability to handle the imide conversion agent that needs isolation in a closed system. It is preferably employed as compared with the immersion method.
[0058]
In the present invention, a tertiary amine that promotes imide conversion and a dehydrating agent that absorbs water generated by imide conversion are used in combination as the imide conversion agent. The tertiary amines are added and mixed in an approximately equimolar or slightly excessive amount with the polyamic acid, and the dehydrating agent is added in an amount about 2 times the molar amount or slightly in excess of the polyamic acid, but adjusts the release point from the support. Adjusted appropriately for
[0059]
The imidizing agent may be added at any point where the polyamic acid solution reaches the film forming die or the coating head from the time when the polymerization of the polyamic acid is completed. In this case, it is preferable to add the mixture shortly before reaching the film forming die or the coating head and mix the mixture with a mixer.
[0060]
As the tertiary amine, pyridine or β-picoline is preferable, but α-picoline, 4-methylpyridine, isoquinoline, triethylamine and the like can also be used. The amount used is adjusted according to the respective activity.
[0061]
As the dehydrating agent, acetic anhydride is most commonly used, but propionic anhydride, butyric anhydride, benzoic acid, formic anhydride and the like can also be used.
[0062]
The polyamic acid film containing the imidization agent, the imidization proceeds due to the heat received from the support and the opposing space on the support, and the polyimidate-polyimide gel film partially imidized is separated from the support. .
[0063]
In this case, the larger the amount of heat applied from the support and the opposite surface space, the faster the imide conversion is promoted, and the faster the film is peeled off, but if the amount of heat is too large, the gas of the organic solvent between the support and the gel film deforms the gel film. Therefore, it is desirable to determine the calorific value in consideration of the position of the peeling point and the film defect.
[0064]
The gel film peeled from the support is introduced into a dryer, where drying of the solvent and completion of the imidization are performed.
[0065]
This gel film contains a large amount of an organic solvent, and its volume is greatly reduced during the drying process. Therefore, in order to concentrate the dimensional shrinkage due to the volume decrease in the thickness direction, both ends of the gel film are gripped by a tenter clip, and the gel film is introduced into a dryer (tenter) by moving the tenter clip, and the gel film is moved into the tenter. It is common to heat and consistently carry out the drying of the solvent and the imide conversion.
[0066]
The drying and the imidization are carried out at a temperature of from 200 to 500C. The drying temperature and the imide conversion temperature may be the same temperature or different temperatures, but at the stage of drying a large amount of the solvent, prevent the bumping of the solvent as a lower temperature, and when the risk of bumping of the solvent is eliminated, raise the temperature to a higher temperature. Preferably, the temperature is increased stepwise so as to promote imide conversion.
[0067]
Note that, in the tenter, the distance between the tenter clips at both ends of the film can be expanded or reduced to perform stretching or relaxation. The stretching ratio is 1.0 to 1.3 times in the machine axis direction. The stretching ratio in the width direction is 0.9 to 1.3 times.
[0068]
A cut sheet-like polyimide film, which preferably contains a block component or a mixed polymer component and is obtained by imide conversion by a chemical conversion method, can be produced by cutting from the continuous film produced as described above. In order to produce a film of a polyamic acid, preferably a polyamic acid containing a block component or a mixed polymer component is produced in a resin or glass flask, as shown in the examples below. A mixed solution obtained by mixing a chemical conversion agent into a solution is cast on a support such as a glass plate, heated, and peeled from the support as a partially imidized self-supporting polyamic acid-polyimide gel film. A method of drying a solvent and imidizing by heating while fixing to a metal fixed frame or the like to prevent dimensional change It is possible to more production.
[0069]
Thus, the polyimide film of the present invention obtained by the imide conversion by the chemical conversion method is more flexible than the polyimide film obtained by the thermal conversion method, for a flexible printed circuit, CSP, BGA or TAB tape. When applied to a metal wiring board substrate, it is suitable for simultaneously satisfying a high elastic modulus, a low coefficient of linear expansion, a low coefficient of moisture expansion, and a low water absorption, and has excellent alkali etching properties. .
[0070]
Therefore, a flexible printed circuit, a metal wiring board for CSP, BGA or TAB, in which the polyimide film of the present invention is used as a base material and metal wiring is provided on the surface thereof, has a high elastic modulus, a low linear expansion coefficient, It exhibits high-performance characteristics of simultaneously satisfying etching properties and film forming properties.
[0071]
In the polyimide film of the present invention, the elastic modulus is preferably from 3 to 5.5 GPa, more preferably from 4 to 5 GPa. If the elastic modulus is small, the film running property is poor and it is difficult to handle, and if it is high, the flexibility is poor.
[0072]
In the polyimide film of the present invention, it is important that the number of times of folding (MIT) is 20000 or more.
[0073]
Further, even when the coefficient of linear expansion (CTE) is too large or too small, the curl becomes too large when bonded to a metal, and the coefficient of linear expansion is in the range of 13 to 22 ppm / ° C.
[0074]
The water absorption is 2% or less, particularly preferably 1% or less.
[0075]
Further, with respect to the alkali etching property, it is a preferable condition that the film is dissolved. The evaluation method is described below, but the evaluation can be performed under alkaline conditions and the erosion rate of the surface can be evaluated. When the alkali etching rate is high, the productivity of through-hole processing of CSP or BGA is good.
[0076]
Since the film is exposed to a high temperature close to 300 ° C. during the solder bath process, the smaller the heat shrinkage, the better. If the heat shrinkage exceeds 1%, it may be difficult to use. It is preferably at most 1%, more preferably at most 0.1%.
[0077]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. In addition, each film characteristic value is measured by the following method.
[0078]
In the following examples, the abbreviations DMAc are dimethylacetamide, PMDA is pyromellitic dianhydride, 44'ODA is 4,4'-oxydianiline, and 34'ODA is 3,4 '. -Is an abbreviation for oxydianiline.
(1) Modulus of elasticity and elongation at break
The elastic modulus was determined from the gradient of the initial rising portion of the tension-strain curve obtained at a tensile speed of 300 mm / min using a Tensilon type tensile tester manufactured by ORIENREC at room temperature according to JIS-K7113.
The elongation at break was taken as the elongation at break of the sample.
(2) Coefficient of linear expansion (CTE)
The coefficient of linear expansion was measured using a TMA-50 thermomechanical analyzer manufactured by Shimadzu Corporation at a heating rate of 10 ° C./min and a cooling rate of 5 ° C./min. It was determined from the dimensional change between 200C and 200C.
(3) Alkali etching property
The alkali etching property is determined by measuring the film thickness before and after contacting one surface of a polyimide film with a 1N potassium hydroxide solution in an ethanol / water mixed solution having a volume ratio of 80/20 at 40 ° C. for 120 minutes. It was determined by measuring with a LITEMATIC type thickness gauge manufactured by the company. Evaluation criteria were determined as follows according to the thickness change rate.
レ ベ ル level shows that the through hole processing speed is high in the alkali etching process of the polyimide film, and good productivity is exhibited. The △ level is a practical level although the through-hole processing speed is not fast. At the × level, the through-hole processing speed is low, which is not a practical level.
：: Thickness change rate 5% or more, Δ: Thickness change rate 1% or more and less than 5%, ×: Thickness change rate less than 1%.
(4) Evaluation of warpage of metal laminate
A polyimide-based adhesive was applied to the polyimide film, and a copper foil was bonded thereon at a temperature of 250 ° C. Thereafter, the temperature was raised to a maximum temperature of 300 ° C. to cure the adhesive, and the obtained metal laminate was cut into a sample size of 35 mm × 120 mm, left at 25 ° C. in a 60% RH atmosphere for 24 hours. Warpage was measured. For the warpage, the sample was placed on a glass plate, and the heights of the four corners were measured and averaged. The evaluation criteria were determined as follows according to the amount of warpage. The X level is a level at which handling becomes difficult when transporting in a later step when used as a metal wiring circuit board.
；: Warpage amount of less than 1 mm, Δ: Warpage amount of 1 mm or more and less than 3 mm, ×; Warpage amount of 3 mm or more.
(5) Film-forming properties
The prepared film was stretched at 400 ° C. by a biaxial stretching method using a biaxial stretching method at a temperature of 400 ° C. using a polymer film biaxial stretching apparatus for research (BIX-703, manufactured by Iwamoto Seisakusho Co., Ltd.). Preheating time 60 seconds, one side stretching speed 10 cm / min,
Double circle; extremely good The stretch ratio at break exceeds 1.3 times.
；: Good The stretch area ratio at break is 1.1 to 1.2 times.
Δ: No problem in practical use.
×: Difficult to form a film.
(6) Heat shrinkage
According to JIS-C2318, the dimensional change before and after heating at 300 ° C. for 1 hour is measured.
[0079]
Heat shrinkage C (%) = 100 (AB) / A
However, A: Film dimensions before heating
B: Film dimensions after heating
；: 0.05% or less, Δ: 0.05% to 0.1% or less, ×: more than 0.1%.
(7) Glass transition temperature (Tg)
It is determined from tan δ and E ′ (storage modulus) from dynamic viscoelasticity measured by a tensile method using a viscoelastic analyzer (RSA2) manufactured by Rheometrics. For simplicity, let Tg be the temperature at which the tan δ peak showing the maximum value starts to rise.
(8) Number of folding endurance (MIT)
According to JIS-P8115, the number of reciprocating bendings until the test piece is cut is measured.
[0080]
[Example 1]
239.1 g of DMAc was placed in a 500 cc glass flask, and 16.07 g of 34 ′ ODA was supplied and dissolved in DMAc. Subsequently, 17.34 g of PMDA was supplied, followed by stirring at room temperature for about 1 hour. Subsequently, 0.149 g of acetic anhydride was added, and the mixture was further stirred for about one hour (completion of the polymerization of the first polymer). Then, 13.15 g of 44 ′ ODA was supplied to the polyamic acid solution, and after completely dissolving, PMDA was added. 14.18 g was supplied, and the mixture was stirred at room temperature for about 1 hour, and a polycarboxylic acid concentration of about 20.3% by weight consisting of a tetracarboxylic dianhydride component and a diamine component having a composition shown in Table 1 with a stoichiometry of about 100 mol%. % Solution was prepared.
[0081]
[Example 2]
239.1 g of DMAc was placed in a 500 cc glass flask, 14.61 g of 34 'ODA was fed into DMAc and dissolved, followed by 15.76 g of PMDA, and the mixture was stirred at room temperature for about 1 hour. Subsequently, 0.149 g of acetic anhydride was added, and the mixture was further stirred for about 1 hour (polymerization of the first polymer was completed). After 14.61 g of 44 ′ ODA was supplied to the polyamic acid solution and completely dissolved, PMDA was added. 15.76 g was supplied, and the mixture was stirred at room temperature for about 1 hour. The polycarboxylic acid concentration was about 20.3% by weight, in which the tetracarboxylic dianhydride component and the diamine component were composed of components having a composition shown in Table 1 with a stoichiometry of about 100 mol%. % Solution was prepared.
[0082]
[Example 3]
In a 500 cc glass flask, 239.1 g of DMAc was charged, and 13.15 g of 34 ′ ODA was supplied and dissolved in DMAc. Subsequently, 14.18 g of PMDA was supplied, followed by stirring at room temperature for about 1 hour. Subsequently, 0.149 g of acetic anhydride was added, and the mixture was further stirred for about 1 hour (polymerization of the first polymer was completed), and 16.07 g of 44 ′ ODA was supplied to the polyamic acid solution, and after completely dissolving, PMDA was added. 17.34 g was supplied, and the mixture was stirred at room temperature for about 1 hour, and a polycarboxylic acid concentration of about 20.3% by weight comprising a tetracarboxylic dianhydride component and a diamine component having a composition shown in Table 1 with a stoichiometry of about 100 mol%. % Solution was prepared.
[0083]
A mixed solution was prepared by mixing 30 g of the polyamic acid solution of Examples 1 to 3 with 12.7 ml of DMAc, 3.6 ml of acetic anhydride, and 3.6 ml of β-picoline, and the mixed solution was placed on a glass plate. After casting, it was heated on a hot plate heated to 150 ° C. for about 4 minutes to form a self-supporting polyamic acid-polyimide gel film, which was peeled off from the glass plate.
[0084]
This gel film is fixed to a metal fixing frame provided with a large number of pins, and heated at 250 ° C. to 330 ° C. for 30 minutes, and then heated at 400 ° C. for about 5 minutes to obtain a polyimide film having a thickness of about 25 μm. Got.
[0085]
Table 1 shows the characteristic value evaluation results of the obtained polyimide film.
[0086]
[Comparative Example 1]
239.1 g of DMAc was placed in a 500 cc glass flask, and 11.66 g of 34 ′ ODA was supplied and dissolved in DMAc. Subsequently, 17.49 g of 44 ′ ODA and 31.75 g of PMDA were sequentially supplied, and room temperature was supplied. And stir for about 1 hour. Finally, a solution having a polyamic acid concentration of about 20.3% by weight comprising a tetracarboxylic dianhydride component and a diamine component having a stoichiometry of about 100 mol% and a composition shown in Table 2 was prepared.
[0087]
[Comparative Example 2]
239.1 g of DMAc was placed in a 500 cc glass flask, and 13.12 g of 34 ′ ODA was supplied and dissolved in DMAc. Subsequently, 16.03 g of 44 ′ ODA and 31.75 g of PMDA were supplied sequentially, and room temperature was added. And stir for about 1 hour. Finally, a solution having a polyamic acid concentration of about 20.3% by weight comprising a tetracarboxylic dianhydride component and a diamine component having a stoichiometry of about 100 mol% and a composition shown in Table 2 was prepared.
[0088]
[Comparative Example 3]
In a 500 cc glass flask, 239.1 g of DMAc was placed, and 14.57 g of 34 ′ ODA was supplied and dissolved in DMAc. Subsequently, 14.57 g of 44 ′ ODA and 31.75 g of PMDA were sequentially supplied, and room temperature was supplied. And stir for about 1 hour. Finally, a solution having a polyamic acid concentration of about 20.3% by weight comprising a tetracarboxylic dianhydride component and a diamine component having a stoichiometry of about 100 mol% and a composition shown in Table 2 was prepared.
[0089]
[Comparative Example 4]
239.1 g of DMAc was placed in a 500 cc glass flask, and 16.03 g of 34 ′ ODA was supplied and dissolved in DMAc. Subsequently, 13.12 g of 44 ′ ODA and 31.75 g of PMDA were supplied sequentially, and room temperature was supplied. And stir for about 1 hour. Finally, a solution having a polyamic acid concentration of about 20.3% by weight comprising a tetracarboxylic dianhydride component and a diamine component having a stoichiometry of about 100 mol% and a composition shown in Table 2 was prepared.
[0090]
These Comparative Examples 1 to 4 were treated in the same manner as in Example 1 with a solution having a polyamic acid concentration of about 20.3% by weight to obtain a polyimide film having a thickness of about 25 μm.
[0091]
Table 2 shows the evaluation results of the characteristic values of the obtained polyimide film.
[0092]
[Comparative Example 5]
In a 500 cc glass flask, 239.1 g of DMAc was charged, and 13.12 g of 34 ′ ODA was supplied and dissolved in DMAc, followed by 17.29 g of PMDA, and the mixture was stirred at room temperature for about 1 hour. Subsequently, 16.03 g of 44 ′ ODA was supplied to the polyamic acid solution, and after completely dissolving, 14.46 g of PMDA was supplied. The mixture was stirred at room temperature for about 1 hour, and the tetracarboxylic dianhydride component and the diamine were added. A solution was prepared having a polyamic acid concentration of about 20.3% by weight, in which the ingredients were of about 100 mole% stoichiometry and composed of the compositions shown in Table 1.
[0093]
[Comparative Example 6]
239.1 g of DMAc was placed in a 500 cc glass flask, 14.61 g of 34 'ODA was fed into DMAc and dissolved, followed by 15.76 g of PMDA, and the mixture was stirred at room temperature for about 1 hour. Subsequently, 14.61 g of 44 ′ ODA was supplied to this polyamic acid solution, and after completely dissolving, 16.03 g of PMDA was supplied. The mixture was stirred at room temperature for about 1 hour, and tetracarboxylic dianhydride component and diamine were added. A solution was prepared having a polyamic acid concentration of about 20.3% by weight, with the ingredients having the composition shown in Table 1 with a stoichiometry of about 100 mol%.
[0094]
[Comparative Example 7]
239.1 g of DMAc was placed in a 500 cc glass flask, and 16.03 g of 34'ODA was supplied and dissolved in DMAc. Subsequently, 17.29 g of PMDA was supplied, followed by stirring at room temperature for about 1 hour. Subsequently, after supplying 13.12 g of 44 ′ ODA to the polyamic acid solution and completely dissolving it, 14.46 g of PMDA was supplied, and the mixture was stirred at room temperature for about 1 hour, and tetracarboxylic dianhydride component and diamine were added. A solution was prepared having a polyamic acid concentration of about 20.3% by weight, in which the ingredients were of about 100 mole% stoichiometry and composed of the compositions shown in Table 1.
[0095]
This polyamic acid solution was treated in the same manner as in Example 1 to obtain a polyimide film having a thickness of about 25 μm.
[0096]
Table 3 shows the evaluation results of the characteristic values of the obtained polyimide film.
[0097]
[Table 1]

[0098]
[Table 2]

[0099]
[Table 3]

[0100]
As is clear from comparison of the results described in Tables 1 and 2, the block polyimide film of the present invention comprising PMDA, 3,4'-ODA, and 4,4'-ODA was compared to a copolymer film. As a result, the number of times of folding and the coefficient of linear expansion have been remarkably improved, and the material has suitable performance as a metal wiring substrate for FPC, CSP, BGA or TAB tape.
[0101]
As is clear from comparison of the results described in Tables 1 and 3, the 3,4′-ODA of the present invention consisting of PMDA, 3,4′-ODA and 4,4′-ODA and the PMDA block were used. The end-capped polyimide film is significantly improved in the number of times of folding and the coefficient of linear expansion compared to a block film in which 3,4'-ODA and PMDA are not end-capped, and is FPC, CSP, BGA, or TAB. It has suitable performance as a metal wiring board for tape.
[0102]
【The invention's effect】
As described above, the polyimide film of the present invention has excellent folding endurance and dimensional stability when applied as a flexible FPC or a metal wiring board for a flexible FPC, even when compared to a polyimide film obtained by copolymerization. And alkali etching properties.

Claims (2)

In a polyimide film obtained from poarimidic acid using 3,4'-oxydianiline as a diamine component, the number of folds of M.I. I. T. Is 20,000 or more, and the coefficient of linear expansion (CTE) is 13 ppm / ° C to 22 ppm / ° C. A metal wiring board, comprising a polyimide wiring board according to claim 1 as a base material and a metal wiring board provided on the surface thereof.