JP2009191162A - Polyimide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide film having an extremely small amount of attached foreign materials on its surface and also excellent in insulation property. <P>SOLUTION: This polyimide film consisting mainly of a polyimide obtained by reacting aromatic tetracarboxylic acids with aromatic diamines and having the ≤0.5 ng/cm<SP>2</SP>total content of the 3 kinds of elements of iron, chromium and nickel, and also having the 0.005 to 0.3 ng/cm<SP>2</SP>content of sulfur element as the attaching foreign materials. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is suitable for use in semiconductors and mounting substrates mainly as a foreign matter adhered to the film surface, which has a small content of three elements of iron, chromium and nickel and a small amount of sulfur element, and has little surface contamination due to conductive foreign matter. This is related to a clean polyimide film. During the final heat treatment when producing a polyimide film, a specific production device is used for the tenter type (film transport) processing section when the precursor film is heat treated at high temperature to form a polyimide film. It is related with the polyimide film which can be obtained by doing.

When a polyimide film is produced, an undried precursor film (green film) is imidized at a high temperature. In this case, when the undried precursor film is transported and dried and heat treated, the amount of these solvents is small. The retained film and precursor film are generally dried and thus shrink. In such film transport / drying / heat treatment, as an apparatus for manufacturing a film by transporting the film in the stretched width direction by holding both ends in the width direction of the film with a large number of pins and clips, A tenter type conveying device for a film (sheet) called a so-called tenter is known (see Patent Document 1).
In addition, it is also known to use a tenter type conveying device for manufacturing a polyimide film (see Patent Document 2).

The film conveying apparatus has been well known for a long time to be used for drying so as not to cause wrinkles in the drying process after dyeing the cloth. In addition to drying the cloth, it is also used for drying an undried plastic film by a solvent casting method while transporting it in the drying step. By using the film conveying apparatus, it is possible to suppress shrinkage of the film in the width direction due to heat during drying and heat treatment, and to prevent wrinkles due to shrinkage from occurring in the film after drying and heat treatment.
The shrinkage of the film occurs not only in the width direction of the film but in all directions. However, the transporting tension acts in the transport direction of the film and has an effect of suppressing the shrinkage. Thus, the strength and flatness required for the dried and heat-treated film can be ensured by transporting the undried film using the film tenter type transport device when drying and heat-treating.

  In particular, since a tenter used for producing a polyimide film is subjected to heat treatment at a temperature exceeding 300 ° C., the heat resistance and durability of the tenter itself are essential for industrially stable production. In particular, stainless steel with high heat resistance is used for the drive part that transports the film. However, since the lubricating oil cannot be used only for the sliding part, there is frictional wear between metal parts. Arise. For this reason, there is a limit in the life of the apparatus, and problems such as contamination of the film product by metal fine powder generated by abrasion have occurred (see Patent Documents 3 to 5).

Japanese Patent Publication No. 39-029211 JP 09-188863 A JP 2007-170493 A JP-A-11-166539 JP 2005-325182 A

  An object of the present invention is to provide a polyimide film that is less contaminated by surface foreign matter having a small content of three elements of iron, chromium, and nickel and a small amount of sulfur.

As a result of intensive studies, the present inventors have found that the content of three kinds of elements, iron, chromium, and nickel, can be increased by using a specific solid lubricating compound for the sliding portion in the tenter type conveying device used for manufacturing the polyimide film. It has been found that it is possible to produce a clean polyimide film that is less contaminated by surface foreign substances that contain less sulfur element.

That is, the present invention has the following configuration. 1. It is a film mainly composed of polyimide obtained by reacting aromatic tetracarboxylic acids and aromatic diamines, and the content of three kinds of elements of iron, chromium and nickel as the adhering foreign matter on the film surface in total polyimide film 0.5 ng / cm ² or less and a sulfur element is characterized in that it is a 0.005~0.3ng / cm ^2.
2. 1. The sulfur is contained as sulfur nitride. The polyimide film as described.

The film of the present invention comprising, as a main component, a polyimide obtained by reacting an aromatic tetracarboxylic acid and an aromatic diamine, and containing three kinds of elements such as iron, chromium, and nickel as adhered foreign matters on the film surface polyimide film the amount 5.0 ng / cm ² or less and elemental sulfur is in total a 0.005~0.3ng / cm ^2, in conjunction with the inherent high heat resistance, a clean film having excellent insulating properties It can be widely used with peace of mind in applications such as semiconductors and mounted circuit boards, and is extremely useful industrially.
The apparatus suitable for the production of the polyimide film of the present invention uses a solid lubricant having both heat resistance and insulation at the sliding part, and is 300 ° C. or higher, preferably 380 ° C. or higher, more preferably 460 ° C. The lubrication action can be maintained even in the above high temperature range, the film can be smoothly conveyed, and a high quality polyimide film can be easily obtained without giving extra vibration to the film during film production. It can also contribute to film production productivity.
By using a specific lubricant for the sliding part during imidization, it is possible to efficiently produce a polyimide film at a high temperature, and the obtained polyimide film has iron, chromium, nickel, sulfur on its surface. It is a clean film with a very small amount of deposited elements and excellent insulating properties. It can be widely used with peace of mind in applications such as semiconductors and mounted circuit boards, and it is extremely significant industrially in terms of quality and production efficiency. .

The present invention is described in detail below.
The polyimide film of the present invention is generally called aromatic tetracarboxylic acids (anhydrides, acids, and amide-bonded derivatives are collectively referred to as classes below) and aromatic diamines (amines and amide-bonded derivatives are collectively named). It is a polyimide film obtained by a method in which a polyamic acid solution obtained by reacting with the above is reacted, and dried to form a film by heat treatment (imidization). Examples of the solvent used in these solutions include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide and the like.
The method for producing a polyimide film of the present invention is most preferably applied particularly when a casting film forming method using an N-methyl-2-pyrrolidone solution or N, N-dimethylacetamide solution of polyamic acid, which is a polyimide precursor, is used. obtain.
Although the polyimide film in this invention is not specifically limited, The combination of the following aromatic diamine and aromatic tetracarboxylic acid (anhydride) is mentioned as a preferable example.
A. Combination with aromatic tetracarboxylic acid having pyromellitic acid residue and aromatic diamine having benzoxazole structure.
B. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a biphenyltetracarboxylic acid skeleton.
C. A combination of an aromatic diamine having a diphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid residue.
In particular, A. A combination for producing a polyimide film having an aromatic diamine residue having a benzoxazole structure is preferred.
Examples of the aromatic diamine having a diaminodiphenyl ether skeleton in the present invention include 4,4′-diaminodiphenyl ether (DADE), 3,3′-diaminodiphenyl ether, and 3,4′-diaminodiphenyl ether and derivatives thereof. Examples of the aromatic diamine having a phenylenediamine skeleton in the invention include p-phenylenediamine, m-phenylenediamine, o-phenylenediamine and derivatives thereof. Examples of the diamine having a benzoxazol skeleton in the present invention include the following. Although the diamine shown by a specific example is mentioned, It is preferable to use these diamines 70 mol% or more of all the diamines, More preferably, 80 mol% or more.

The molecular structure of aromatic diamines having a benzoxazole structure is not particularly limited, and specific examples include the following.

  Among these, from the viewpoint of easy synthesis, each isomer of amino (aminophenyl) benzoxazole is preferable, and 5-amino-2- (p-aminophenyl) benzoxazole is more preferable. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.

  In the present invention, one or two or more diamines exemplified below may be used in combination as long as they are 30 mol% or less of the total diamine. Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl]. Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 3,3′-diamino Diphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-dia Nodiphenyl sulfide, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide, 4,4′-diaminodiphenyl sulfoxide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4 , 4′-diaminodiphenylsulfone, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4, 4′-diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-amino) Phenoxy) phenyl] ethane, 1,1-bis [4- 4-aminophenoxy) phenyl] propane, 1,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, , 4-bis [4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl ] Butane, 2- [4- (4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-a Minophenoxy) -3-methylphenyl] propane, 2- [4- (4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2- Bis [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexa Fluoropropane, 1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4 -Aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-amino) Enoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1, 3-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] Benzene, 4,4′-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) ) Phenyl] propane, 3,4'-diaminodiphenyl sulfide, 2,2-bis [3- (3-aminophenoxy) phenyl -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1 , 2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4′-bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-Amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} fe Sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethyl Benzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-fluoro) Phenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4 -Amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene, 3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-dipheno Cibenzophenone, 3,4'-diamino-4,5'-diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino- 4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4′-diamino-4,5′-dibiphenoxybenzophenone, 3,3′-diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4′-diamino-4 -Biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino-4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) Benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-bi) Phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- ( 4-amino-α, α-dimethylbenzyl) phenoxy] benzonitrile and some or all of the hydrogen atoms on the aromatic ring of the aromatic diamine are halogen atoms, An alkyl group having 1 to 3 carbon atoms, an alkoxyl group, a cyano group, or an alkyl group or an alkoxyl group having 1 to 3 carbon atoms in which some or all of the hydrogen atoms of the alkyl group or alkoxyl group are substituted with halogen atoms. Examples thereof include substituted aromatic diamines.

<Aromatic tetracarboxylic acid anhydrides>
Specific examples of the aromatic tetracarboxylic acid anhydrides used in the present invention include the following.

  These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as long as they are 30 mol% or less of the total tetracarboxylic dianhydrides. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3 5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3 -(1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane-1 -(2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ', 4'-tetracarboxylic dianhydride, bicyclo [2.2.1] heptane -2,3,5,6-tetracarboxylic dianhydride, Cyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid A dianhydride etc. are mentioned. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The solvent used when the polyamic acid is obtained by reacting (polymerizing) the aromatic tetracarboxylic acid and the aromatic diamine is not particularly limited as long as it dissolves both the raw material monomer and the produced polyamic acid. Are preferably polar organic solvents such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, Examples include hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, and halogenated phenols. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the mass of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by mass, The amount is preferably 10 to 30% by mass.

  Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for 30 minutes. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic anhydrides to the solution of aromatic diamines. The mass of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40 mass%, more preferably 10 to 30 mass%, and the viscosity of the solution is measured by a Brookfield viscometer (25 ° C.). And from the stability point of liquid feeding, Preferably it is 10-2000 Pa.s, More preferably, it is 100-1000 Pa.s.

Vacuum defoaming during the polymerization reaction is effective for producing a good quality polyamic acid solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mol per mol of aromatic diamine.
In order to form a polyimide film from the polyamic acid solution obtained by the polymerization reaction, a green film (a self-supporting precursor film is obtained by applying the polyamic acid solution on a support and drying, then, Examples of the method of imidization reaction by subjecting the green film to heat treatment include, but are not limited to, application of the polyamic acid solution to the support, including casting from a slit-attached base and extrusion by an extruder. A conventionally known solution coating means can be appropriately used.

  The conditions for drying the polyamic acid coated on the support to obtain a green sheet are not particularly limited, and examples include a temperature of 70 to 150 ° C. and a drying time of 5 to 180 minutes. A conventionally known drying apparatus that satisfies such conditions can be applied, and examples thereof include hot air, hot nitrogen, far infrared rays, and high frequency induction heating. Next, in order to obtain a target polyimide film from the obtained green sheet, an imidization reaction is performed. As a specific method thereof, a conventionally known imidization reaction can be appropriately used. For example, there may be mentioned a method (so-called thermal ring closure method) in which an imidization reaction proceeds by subjecting to a heat treatment after performing a stretching treatment as necessary using a polyamic acid solution not containing a ring closure catalyst or a dehydrating agent. The heating temperature in this case is exemplified by 100 to 500 ° C., and from the viewpoint of film physical properties, more preferably, a two-stage heat treatment in which treatment is performed at 350 to 500 ° C. for 3 to 20 minutes after treatment at 150 to 250 ° C. for 3 to 20 minutes. Is mentioned.

Another example of the imidization reaction is a chemical ring closure method in which a polyamic acid solution contains a ring closure catalyst and a dehydrating agent, and the imidization reaction is performed by the action of the ring closing catalyst and the dehydrating agent. In this method, after the polyamic acid solution is applied to the support, the imidization reaction is partially advanced to form a film having self-supporting property, and then imidization can be performed completely by heating. In this case, the condition for partially proceeding with the imidization reaction is preferably a heat treatment for 3 to 20 minutes at 100 to 200 ° C., and the condition for allowing the imidization reaction to be completely performed is preferably 200 to 400 ° C. For 3 to 20 minutes. The thickness of the polyimide film in the present invention is not particularly limited, but is preferably 25 μm or less, more preferably 12 μm or less, most preferably 7 μm or less, and can greatly contribute to the lightness and thinness of electronic components.
Conventionally, it is difficult to industrially stably produce a long film of a polyimide film of 7.0 μm or less, particularly 5.0 μm or less, and these obtained ultrathin polyimide films have extremely uneven thickness. For example, the thickness unevenness of a commercially available 7.5 μm polyimide film is about 25%, and there is a problem in quality in electronic parts that require dimensional accuracy. It is something to be solved.
The thickness of the polyimide film can be easily controlled by the amount of the polyamic acid solution applied to the support and the concentration of the polyamic acid solution.

  In the present invention, a method for obtaining a polyimide film having a thickness of 7 μm or less, in which these thickness spots are 20% or less, is not particularly limited, but as a preferred method, (1) aromatic tetracarboxylic acids A polyamic acid obtained by reacting a diamine with an aromatic diamine is cast and dried to obtain a precursor film (polyamic acid film), and the precursor film is formed at both ends of the film in the width direction. The gripping is done by pinching with a large number of clips or piercing with a large number of pins provided on the pin sheet, and the thickness to be imidized by a tenter method that conveys the film in a state stretched in the width direction and / or the conveyance direction A polyimide film manufacturing method for obtaining a polyimide film of 7 μm or less, and fills at both end portions in the width direction of the precursor film. A method for producing a polyimide film in which gripping is fixed by stacking and / or piercing a precursor (polyamic acid) film to be imidized and an easy-adhesive polyimide film provided with an adhesive layer on a thin polyimide film (2) A so-called precursor obtained by slitting a precursor film obtained by casting and drying a polyamic acid obtained by reacting an aromatic tetracarboxylic acid and an aromatic diamine with the narrow polyimide film. The method of said (1) which is a film (green film) is mentioned.

It can be easily inferred that the metal elements whose contents are limited in the present invention, such as iron, chromium, and nickel, are derived from stainless steel used as a member of a film production apparatus. It is well known that wear occurs in the sliding portion, particularly in a mechanical device having a driving portion. Normally, lubricating oil is used to avoid wear and facilitate driving. However, in an apparatus used for high-temperature processing such as the present invention, lubricating oil is deteriorated due to heat deterioration and oxidation deterioration. I can't. As a result, the fine powder of stainless steel generated by abrasion is taken in as a conductive impurity attached to the film or half-encapsulated in the film. Such metal impurities are often located in the vicinity of the film surface, and when the film is used for a circuit board, it may cause a short circuit between circuits as a conductive foreign matter. In addition, since an electrode potential difference is generated with copper, which is the main constituent material of the circuit, it may trigger electrolytic corrosion or ion migration. Furthermore, when the circuit is subjected to electroless plating, it may exhibit a catalytic action and cause abnormal deposition of the plating. Further, since the metal element itself belongs to a ferromagnetic material, it may cause noise due to a microscopic magnetic effect and hinder the operation of the element.
In the present invention, the total content of three elements of iron, chromium and nickel is essential to be 0.5 ng / cm 2 or less in total, more preferably 0.3 ng / cm 2 or less, and further 0.15 ng / cm 2 or less. More preferred is 0.08 ng / cm 2 or less. Although the minimum of content is not specifically limited, It is 0.001 ng / cm <2>, Preferably it is 0.005 ng / cm <2>. Such a metal component is also a main component of stainless steel which is also a main material of an apparatus used for the synthesis and polymerization of polyimide film raw materials, and it is difficult to avoid an extremely small amount in a strict sense. However, it must be understood that there is a several-digit difference from the amount of contamination caused by metal wear or the like generated in the driving part of the film forming machine base which is the subject of the present invention.

It will be readily understood that sulfur, whose content is limited in the present invention, is derived from the solid lubricant. Solid lubricants themselves are peeled off into a fine layer due to wear, and a lubricant is produced by forming a thin film on the sliding part. As is apparent from the principle, the solid lubricant itself becomes a fine layered particle and has a possibility of being mixed as an impurity of the film. Therefore, solid lubricants are not something that should be used in large quantities, but are required to be used in moderate and moderate amounts. The elemental sulfur is often located in the vicinity of the film surface as in the case of iron, nickel, chromium and the like. As a matter of course, these can cause a short circuit between lines of the fine line circuit or a break of the wiring as a foreign matter. Furthermore, in recent flip chip mounting, since the functional surface of the semiconductor element comes into contact with the wiring circuit, it is necessary to pay particular attention to trivalent or pentavalent elements that can be ionic impurities and donors or acceptors on the surface of the wiring circuit. There is. In flip chip mounting, the bonding between the pad on the semiconductor element side and the electrode on the substrate side is often due to metal / metal pressure diffusion, and if the circuit continues to be driven at a high temperature, the electrode bonding part is solid even during device use. It is known that diffusion proceeds. In the case where sulfur element is mixed in such a place, there is a fear of direct influence on the semiconductor element. The solid lubricant used in the sliding part in the imidization process of the production apparatus suitable for the production of the polyimide film of the present invention is a non-metal or metal sulfide, and the metal sulfide is niobium sulfide. Iron sulfide, tungsten disulfide, molybdenum disulfide and the like.
In the present invention, it is essential that the sulfur element content is 0.0001 to 0.3 ng / cm 2. A preferable range of the content of elemental sulfur is 0.002 to 0.1 ng / cm 2, and more preferably 0.003 to 0.03 ng / cm 2. Although it is not possible to deny the possibility that such elemental sulfur is rarely mixed as an impurity in the catalyst component used during the synthesis of the polyimide film raw material, it is used in the film-forming machine base that is the subject of the present invention. It should be understood that there is a difference of several orders of magnitude compared to the case where the resulting solid lubricant component is the cause.
The method for causing these heat-resistant compounds having a solid lubricating action to act on the sliding portion is not particularly limited.For example, a mechanism for pressing a solid lubricant stick from the lower part of the roller to the roller on which the chain block is placed is added. There is a method in which a solid lubricant component is transferred in advance to a roller rotating body portion and a chain block in contact with the roller.
As the solid lubricant stick, the fixed lubricant exemplified above is used as a relatively soft metal, for example, Ni, Fe, Co, Cu, Sn, Ag, Pb, Mn, Cr, Mo, W, Nb, Ta, Al, Zn. , Ti and the like sintered by powder metallurgy can also be used.
Because of the action of these heat-resistant compounds having a solid lubricating action, the manufacturing apparatus of the present invention can suppress wear of the sliding part even when a high-temperature heat treatment at 300 ° C. or higher is operated for a long time. It is possible to reduce the fundamental frequency of the frictional sound generated during film transport, which is thought to be generated by the wear of the film, to 3 kHz or less, improve the working environment, and greatly reduce the amount of dust such as metal on the manufactured film surface. it can.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. In addition, the evaluation method of the physical property in the following examples is as follows.

1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone (or N, N-dimethylacetamide) so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. with an Ubbelohde type viscosity tube. (When the solvent used for preparing the polyamic acid solution was N, N-dimethylacetamide, the polymer was dissolved using N, N-dimethylacetamide and measured.)
2. The thickness of the polyimide film The thickness was measured using a micrometer (Finereuf, Millitron 1245D).
3. Specimen obtained by cutting a polyimide film to be measured into a strip of 100 mm × 10 mm in the flow direction (MD direction) and the width direction (TD direction), respectively. It was. Using a tensile tester (manufactured by Shimadzu Corp., Autograph (R) model name AG-5000A) under the conditions of a tensile speed of 50 mm / min and a distance between chucks of 40 mm, the MD direction (flow direction) and TD direction (width direction) respectively. The tensile modulus, tensile strength at break and tensile elongation at break were measured.

4). Quantitative determination of the amount of foreign material adhering to the surface (iron, nickel, chromium) Twenty-five squares with a side of 50 mm were randomly cut out from the obtained film, and they were placed in 500 ml of 10% aqueous hydrochloric acid, and the front and back of each film were sufficiently hydrochloric acid. After soaking at room temperature for 24 hours so as to be in contact with the aqueous solution, the film was taken out, and the metal components and the like contained in the aqueous hydrochloric acid solution were quantified by atomic absorption analysis.
The surface adhering foreign matter components were iron, nickel, and chromium, which are the main components of stainless steel presumed to be used in the pin tenter sliding portion, and these were detected and measured. These individual amounts were divided by the film area to obtain the amount of foreign matter adhered to the surface.
Individual surface adhering foreign matter amount [ng / cm ² ] = Individual surface adhering foreign matter amount [ng] / film area [cm ² ]
5. Quantitative determination of the amount of foreign material adhering to the surface (sulfur) 25 squares each having a side of 50 mm were cut out from the obtained film, and they were placed in 500 ml of 10% aqueous hydrochloric acid so that the front and back of each film were in full contact with the aqueous hydrochloric acid. After being immersed for 24 hours at room temperature, the film was taken out, and the hydrogen sulfide contained in the hydrochloric acid aqueous solution was quantitatively analyzed by gas chromatographic analysis, and divided by the film area to obtain the amount of foreign matter adhered to the surface.
Amount of foreign matter adhering to the surface of sulfur [ng / cm ² ] = Amount of foreign matter adhering to the surface of sulfur [ng] / Film area [cm ² ]

[Reference Example 1]
(Preliminary dispersion of inorganic particles)
1.22 parts by mass of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 420 parts by mass of N-methyl-2-pyrrolidone, the wetted part of the container, and the infusion pipe are austenitic stainless steel The mixture was placed in a container of SUS316L and stirred with a homogenizer T-25 basic (manufactured by IKA Labortechnik) at a rotation speed of 1000 rpm for 1 minute to obtain a preliminary dispersion. The average particle size in the preliminary dispersion was 0.11 μm.
(Preparation of polyamic acid solution)
A nitrogen inlet tube, a thermometer, a liquid contact part of a container equipped with a stirring rod, and a pipe for infusion were substituted with nitrogen in the reaction container made of austenitic stainless steel SUS316L, and then 223 parts by mass of 5-amino-2- ( p-Aminophenyl) benzoxazole was added. Next, 4000 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then the preliminary dispersion obtained above was added with 420 parts by mass and 217 parts by mass of pyromellitic dianhydride. When the mixture was stirred at ° C. for 24 hours, a brown viscous polyamic acid solution A was obtained. The reduced viscosity (ηsp / C) was 3.8.

[Reference Example 2]
Nitrogen introduction tube, thermometer, vessel wetted part equipped with stirring rod, and infusion pipe were replaced with nitrogen in the reaction vessel of austenitic stainless steel SUS316L, and then 5-amino-2- (p-aminophenyl) ) After adding 223 parts by mass of benzoxazole and 4416 parts by mass of N, N-dimethylacetamide and completely dissolving them, Snowtex DMAC-ST30 (manufactured by Nissan Chemical Industries, Ltd.) 40 in which colloidal silica is dispersed in dimethylacetamide .5 parts by mass (including 8.1 parts by mass of silica) and 217 parts by mass of pyromellitic dianhydride are added and stirred at a reaction temperature of 25 ° C. for 24 hours to obtain a brown and viscous polyamide acid solution B. It was. Ηsp / C of this product was 4.0.

[Reference Example 3]
(Preliminary dispersion of inorganic particles)
7.6 parts by mass of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 390 parts by mass of N-methyl-2-pyrrolidone, and the infusion part are austenitic stainless steel SUS316L And stirred for 1 minute at a rotation speed of 1000 rpm with a homogenizer T-25 basic (manufactured by IKA Labortechnik) to obtain a preliminary dispersion.
(Preparation of polyamic acid solution)
The liquid contact part of the vessel equipped with a nitrogen introduction tube, a thermometer, a stirring rod, and the pipe for infusion were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 200 parts by mass of diaminodiphenyl ether was added. Next, after 3800 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 390 parts by mass and 217 parts by mass of pyromellitic dianhydride were added to the preliminary dispersion obtained above. When the mixture was stirred at 0 ° C. for 5 hours, a brown viscous polyamic acid solution C was obtained. The reduced viscosity (ηsp / C) was 3.7.

[Reference Example 4]
(Preliminary dispersion of inorganic particles)
3.7 parts by weight of amorphous silica spherical particle Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 420 parts by weight of N-methyl-2-pyrrolidone, the liquid contact part of the container, and the infusion pipe are austenitic stainless steel SUS316L And stirred for 1 minute at a rotation speed of 1000 rpm with a homogenizer T-25 basic (manufactured by IKA Labortechnik) to obtain a preliminary dispersion.
(Preparation of polyamic acid solution)
The wetted part of the vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod, and the infusion piping were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 108 parts by mass of phenylenediamine was added. Next, after 3600 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 420 parts by mass and 292.5 parts by mass of biphenyltetracarboxylic dianhydride were added to the preliminary dispersion obtained above. When the mixture was stirred at 25 ° C. for 12 hours, a brown viscous polyamic acid solution D was obtained. This reduced viscosity (ηsp / C) was 4.5.

[Comparative Examples 1-4]
The polyamic acid solution obtained in Reference Examples 1 to 4 was coated on a stainless steel endless continuous belt mirror-finished using a die coater (coating width 1240 mm) and dried at 90 to 115 ° C. for 10 minutes. The polyamic acid film which became self-supporting after drying was peeled off from the support and cut at both ends to obtain respective green films.
The obtained green film is passed through a pin tenter having a pin sheet in which pins are arranged so that the pin interval is constant when the pin sheets are arranged, and is gripped by inserting the film end into the pin. The pin sheet interval is adjusted so that it does not break and unnecessary tarmi is generated, and the final pin sheet interval is 1140 mm. The first sheet is conveyed at 170 ° C. for 2 minutes and 230 as the second stage. Heating was carried out at 2 ° C. for 2 minutes and in the third stage 485 for 6 minutes to advance the imidization reaction. Then, it cooled to room temperature in 2 minutes, the part where the flatness of the both ends of a film was bad was cut off with the slitter, it wound up in roll shape, and each polyimide film of Comparative Examples 1-4 which exhibits brown was obtained. Here, the pin sheet is fixed to a stainless steel block connected in a chain shape, and is transported on a stainless steel roller as a connecting body. Lubricating oil is not used because the third stage is hot. Here, the length of the pin sheet is 65.0 mm, and the pin interval is 7.0 mm. Table 1 shows measurement results such as the characteristics of the obtained polyimide film and the peak frequency of noise. During the tenter operation, any polyamic acid film is used, and mechanical sounds, particularly high-pitched sounds, which are sliding sounds between metals, are intermittently generated, and the noise level is high, which hinders conversation near the pin tenter. Came.

[Examples 1 to 4]
The polyamic acid solutions of Reference Examples 1 to 4 were coated and dried on a stainless steel endless continuous belt mirror-finished in the same manner as in Example, and the polyamic acid film that became self-supporting after drying was peeled off from the support. Each green film having a thickness of 21 μm was obtained.
These obtained green films were heat-treated under the same conditions using a pin tenter substantially similar to the comparative example. However, in the embodiment, a mechanism for pressing the solid lubricant stick from the bottom of the roller is added to the roller on which the chain block is placed, and the solid lubricant component is sufficiently applied to the roller block and the chain block in contact with the roller in advance. After the transfer, heat treatment was performed.
The others were heat-treated under the same conditions as in the comparative example, and the portions with poor flatness at both ends of the film were cut off with a slitter, rolled up into a roll, and the respective polyimide films of Examples 1 to 4 exhibiting brown color were obtained. . Table 1 shows the results, such as the characteristics of the obtained polyimide film and the peak frequency of noise. In addition, the mechanical drive sound during the tenter operation was a noise in the mid-low range centered on the drive sound of the motor and the chain, and the noise level was sufficiently lower than that of the comparative example, and there was no particular problem in conversation.
The solid lubricant component used here was a mixture of 85 mass% niobium sulfide having an average particle diameter of 2 μm and an Fe—Ni—B alloy (15 mass%) having an average particle diameter of 5 μm as a solid lubricant, and further a metal component. After mixing silver (20 mass%), tin (10 mass%) copper (35 mass%) with an average particle diameter of 2 to 4 μm, and mixing and pulverizing with a ball mill. This was pressed into a pellet form at a pressure of about 5 tons / square cm, and sintered at 1150 ° C. for 30 minutes under a low vacuum of 1.0 × 10 ⁻² Pa level.

[Comparative Examples 5 to 8]
The polyamic acid solution obtained in Reference Examples 1 to 4 was coated on a stainless steel endless continuous belt mirror-finished using a die coater (coating width 1240 mm) and dried at 90 to 115 ° C. for 10 minutes. The polyamic acid film which became self-supporting after drying was peeled off from the support and cut at both ends to obtain respective green films.
The obtained green film was passed through a clip tenter equipped with a clip while laminating a narrow slit film having a width of 35 mm (adhesive narrow slit film) on both side ends, and the film end was Hold with clips, adjust the clip width appropriately so that the film does not break and the excess tarmi of the film does not occur, and transport it so that the final clip interval is 1140 mm, the first stage is 170 ° C. for 2 minutes The second stage was heated at 230 ° C. for 2 minutes, and the third stage 485 was heated for 6 minutes to allow the imidization reaction to proceed. Then, it cooled to room temperature in 2 minutes, cut off the part where the flatness of the both ends of a film was bad with a slitter, wound up in roll shape, and obtained each polyimide film of Comparative Examples 5-8 which exhibits brown. Here, the clip is fixed to a stainless steel block connected in a chain shape, and is transported on the rail by a stainless steel roller as a chain connection body. Lubricating oil is not used because the third stage is hot. Table 1 shows the measurement results such as the characteristics of the obtained polyimide film and the peak frequency of noise. During the tenter operation, any polyamic acid film is used, and mechanical sounds, particularly high-pitched sounds, which are sliding sounds between metals, are intermittently generated, and the noise level is high, which hinders conversation near the pin tenter. Came.

[Examples 5 to 8]
The polyamic acid solutions of Reference Examples 1 to 4 were coated and dried on a stainless steel endless continuous belt mirror-finished in the same manner as in Example, and the polyamic acid film that became self-supporting after drying was peeled off from the support. Each green film having a thickness of 46 μm was obtained.
These obtained green films were heat-treated in the same conditions as in Comparative Examples 5 to 8 using a clip tenter. However, in the embodiment, a mechanism for pressing the roller solid lubricant stick that conveys the chain is added, and the solid lubricant component (mixture of niobium sulfide and iron sulfide is previously applied to the roller rotating body portion and the chain block that contacts the roller. A mass ratio of 1: 1) was sufficiently transferred, and then heat treatment was performed.
Others were heat-treated under the same conditions as in the comparative example, and the portions with poor flatness at both ends of the film were cut off with a slitter, rolled up into a roll shape, and the respective polyimide films of Examples 5 to 8 exhibiting brown color were obtained. . Table 1 shows the results, such as the characteristics of the obtained polyimide film and the peak frequency of noise. In addition, the mechanical drive sound during the tenter operation was a noise in the mid-low range centered on the drive sound of the motor and the chain, and the noise level was sufficiently lower than that of the comparative example, and there was no particular problem in conversation.
Here, the solid lubricant component used was 35% by mass (mixture of niobium sulfide and iron sulfide having an average particle size of 2.5 μm in a mass ratio of 1: 1) as a solid lubricant, and an average particle size of 2 to 2 as a metal component. 4 μm of silver (20% by mass), tin (10% by mass) and copper (35% by mass) are mixed and mixed and ground in a ball mill. A material which was pressed into a pellet at a pressure of about 5 tons / square cm and sintered under a low vacuum of 1.0 × 10 −2 Pa level at 1000 ° C. for 60 minutes was used.
Tables 1 to 4 show the physical properties of the films obtained in these Examples and Comparative Examples.

As shown in Tables 1 to 4, in the comparative example, the amount of adhering foreign matter on the film surface is large, but in the examples, both the noise level and the central frequency of noise are reduced, and the amount of adhering foreign matter, especially the total element amount of iron, chromium, and nickel. Is significantly reduced, and the amount of sulfur element is found to be below a certain value.
As described above, the amount of foreign matter on the surface of the film obtained by the method using the specific solid lubricant of the present invention, iron, chromium, nickel, and sulfur can be greatly reduced. The polyimide film is industrially significant as a casting film forming method, and the obtained polyimide film is a clean film excellent in insulation in addition to the original high heat resistance, and is safe for use in semiconductors and mounted circuit boards. It can be used widely in mind and is extremely useful industrially.

  The present invention can significantly reduce the amount of foreign matter adhered to the surface of a polyimide film by using a specific solid lubricant in the production of films such as pin tenters and clip tenters that require high temperatures for processing polyimide films. In addition, the obtained polyimide film has high heat resistance and high insulation, and can be widely used with peace of mind in applications such as semiconductors and mounted circuit boards.

Claims (2)

It is a film mainly composed of polyimide obtained by reacting aromatic tetracarboxylic acids and aromatic diamines, and the content of three kinds of elements of iron, chromium and nickel as the adhering foreign matter on the film surface in total polyimide film 0.5 ng / cm ² or less and a sulfur element is characterized in that it is a 0.0001~0.3ng / cm ^2.   The polyimide film according to claim 1, wherein sulfur is contained as a metal sulfide.