JP6765272B2 - Polyimide film - Google Patents

Description

The present invention relates to a polyimide film and a method for producing the same. Furthermore, the present invention relates to a flexible metal laminated plate provided with the polyimide film and a metal foil.

Flexible printed wiring boards (FPCs) are generally made of various insulating materials and have a flexible insulating film as a substrate, which is bonded to the surface of the substrate by heating and crimping a metal foil. Manufactured by the method. As the insulating film, a polyimide film having excellent heat resistance and electrical insulating properties is preferably used.

In recent years, in order to achieve miniaturization and weight reduction of electronic devices, the wiring provided on the substrate has been miniaturized, and the components to be mounted are also miniaturized and have high density. Therefore, if the dimensional change after forming the fine wiring becomes large, there arises a problem that the component and the substrate are not well connected due to the deviation from the component mounting position at the design stage.

Attempts are being made to reduce such dimensional changes in polyimide films. For example, in Patent Document 1 (Japanese Unexamined Patent Publication No. 2015-10107), the film forming width is 1 m or more, and the orientation angles (θ) of the film are 45 ° and 135 with reference to the machine transport direction (MD) of the film. The orientation coefficient AI (45, 135) value at ° is 12 or less over the entire width, and the dimensional change rate before and after etching the flexible metal laminate in the diagonal (45 °, 135 °) direction over the entire width is -0.05. It is described that a polyimide film having a thermoplastic polyimide layer of about 0.05% and at least one side having a thickness of 0.5 to 20 μm reduces the step change.

As described above, further improvement of the polyimide film is required.

JP 2015-10107

An object of the present invention is to provide a polyimide film having little variation in dimensional change in the film forming width direction and a flexible metal laminated plate provided with the polyimide film.

Another object of the present invention is to provide a polyimide film having a small one-sided elongation after heat treatment and a flexible metal laminate provided with the polyimide film.

Still another object of the present invention is to provide a method for producing a polyimide film having the above-mentioned characteristics with excellent film-forming properties.

According to the studies by the present inventors, it has been found that the film of Patent Document 1 and the like can improve the dimensional change to some extent, but the film as a whole has a variation in the dimensional change and a one-sided elongation phenomenon due to heat treatment occurs. In addition, we considered adjusting imidization on the support in order to reduce dimensional change variation and one-sided elongation, but it was difficult to achieve both because film tearing occurred such as tearing of the gripped part. there were.

Under these circumstances, as a result of further diligent research, the present inventors have defined the orientation of not only a specific angle but also all angles with a specific AI value in the polyimide film as in Patent Document 1. By combining this specific AI value and a specific coefficient of linear expansion, it is possible not only to reduce the dimensional change but also to suppress the variation, and it is possible to reduce the one-sided elongation after heat treatment. It has been found that it is necessary to adjust the imidization rate of the gel film, which is a precursor film of the polyimide film, in order to adjust the AI value and the coefficient of linear expansion while ensuring the film-forming property. Further research was carried out based on this finding, and the present invention was completed.

That is, the present invention relates to the following invention.
[1] The coefficient of linear expansion αMD in the transport direction (MD) and the coefficient of linear expansion αTD in the width direction (TD) of the film are both 7 ppm / ° C. or less, and the following formula is used when the propagation speed V of the ultrasonic pulse is measured. A polyimide film having an anisotropy index AI value represented by (1) of 15 or less over the entire width.
AI = (VMAX ^ 2-VMIN ^ 2) / (VMAX ^ 2 + VMIN ^ 2)
(In the equation, VMAX ^ 2 indicates the square of the maximum value of the pulse propagation velocity, and VMIN ^ 2 indicates the square of the minimum value of the pulse propagation velocity.)
[2] The polyimide film according to [1], wherein the film-forming width is 1000 mm or more, and the difference in linear expansion coefficient (difference between the maximum value and the minimum value) of αMD in the film width direction is 2 ppm / ° C. or less.
[3] The method according to [1] or [2], wherein the film-forming width is 1000 mm or more, and the difference in linear expansion coefficient (difference between the maximum value and the minimum value) of αTD in the film width direction is 2 ppm / ° C. or less. Polyimide film.
[4] A type of polyimide film selected from the group consisting of an aromatic diamine component containing paraphenylenediamine, pyromellitic dianhydride and 3,3'-4,4'-diphenyltetracarboxylic dianhydride. The polyimide film according to any one of [1] to [3], which is composed of a polyimide containing the above acid anhydride component as a polymerization component.
[5] A gel film (particularly a partially dried and cured gel film having self-supporting property) is prepared by casting and coating a polyimide precursor solution on a support, and the gel film is heat-treated [particularly. The method for producing a polyimide film according to any one of [1] to [4], wherein heat treatment (drying and heat treatment) is performed by passing the gel film through a heating furnace while grasping both ends in the width direction.
[6] The production method according to [5], wherein the gel film (gel film peeled from the support) has an imidization rate of 55 to 75%.
[7] A flexible metal laminate provided with the polyimide film according to any one of [1] to [4] and a metal foil.

The polyimide film of the present invention has little variation in dimensional change in the film-forming (film) width direction. Further, the polyimide film of the present invention has a small one-sided elongation after heat treatment.
In the flexible metal laminated plate obtained by using the polyimide film of the present invention, the dimensional change before and after removing the metal foil is small in the polyimide film film forming width direction.
Therefore, it can be suitably used for a flexible metal laminated plate (FPC) or the like in which fine wiring is formed.
Further, according to the production method of the present invention, a polyimide film having the above-mentioned excellent characteristics can be produced with excellent film forming property by adjusting the imidization ratio of the gel film or the like.

It is a figure which shows the one-sided elongation value measured in an Example.

[Polyimide film]
The polyimide film of the present invention has a specific coefficient of linear expansion and anisotropy index (AI value). By having such a specific coefficient of linear expansion and a specific AI value in combination, it is possible to efficiently obtain a film having little variation in dimensional change and little elongation after heat treatment.

The linear expansion coefficient and AI value are, for example, the composition of the polyimide constituting the film, the film manufacturing conditions (the imidization rate of the gel film, the stretching conditions, the temperature of the support, the imidization rate, the drying conditions, etc.). It can be adjusted by selecting.

First, in the polyimide film of the present invention, both the linear expansion coefficient αMD in the transport direction (MD) and the linear expansion coefficient αTD in the width direction (TD) are 7 ppm / ° C. or lower, preferably 6 ppm / ° C. or lower, more preferably. Is 5 ppm / ° C or lower, particularly 4.5 ppm / ° C or lower.

In the polyimide film of the present invention, the difference in the coefficient of linear expansion of αMD in the film width direction may be, for example, 3 ppm / ° C. or less, preferably 2 ppm or less, and more preferably 1.5 ppm or less.

In the polyimide film of the present invention, the difference in linear expansion coefficient of αTD in the film width direction may be, for example, 3 ppm / ° C. or less, preferably 2 ppm / ° C. or less, and more preferably 1.5 ppm or less.

The coefficient of linear expansion can be measured using, for example, TMA-50 (manufactured by Shimadzu Corporation) under the conditions of a measurement temperature range of 50 to 200 ° C. and a heating rate of 10 ° C./min.

For the linear expansion coefficient, for example, select two points 200 mm inside from both ends of the film forming width in the film width direction, and within the range of the straight line connecting the two points, within ± 200 mm of the central portion on the straight line including the two points. The coefficient of linear expansion can be measured at at least these five points by selecting one point and an arbitrary two points, and can be obtained as an average value of the obtained measured values.

For the difference (variation) in the coefficient of linear expansion in the film width direction, for example, select two points that are 200 mm inward from both ends of the film forming width in the film width direction, and the difference is within the range of a straight line connecting the two points. Select one point within ± 200 mm of the central part on the straight line including the point and any two points, measure the coefficient of linear expansion at at least these five points, and of the obtained measured values, the maximum value and the minimum value It can be obtained as a difference.

Further, in the polyimide film of the present invention, the anisotropy index AI value represented by the following formula when the propagation speed V of the ultrasonic pulse is measured is 15 or less over the entire width [for example, 0 to 15 (for example, 0. 5 to 14.8), preferably 14.5 or less (eg, 1-14.2), more preferably 14 or less (eg, 2 to 13.8), especially 13.5 or less (eg, 3 to 13. 2)].

AI = (VMAX ^ 2-VMIN ^ 2) / (VMAX ^ 2 + VMIN ^ 2)
(In the equation, VMAX ^ 2 indicates the square of the maximum value of the pulse propagation velocity, and VMIN ^ 2 indicates the square of the minimum value of the pulse propagation velocity.)

The AI value can be measured, for example, as follows.
Select two points that are 200 mm inside from both ends of the film forming width in the film width direction, and within the range of the straight line connecting the two points, one point within ± 200 mm of the central part on the straight line including the two points and further arbitrary Select 2 points and measure AI at at least these 5 points. AI can be measured using SST-2500 manufactured by Nomura Shoji. When the SST-2500 is used, the ultrasonic velocity in 16 directions is automatically measured in 11.25 ° increments from 0 to 180 ° in the plane direction of the film (0 ° is parallel to the MD). The angle (orientation angle) means the direction of the orientation axis, and the machine transport direction (MD) of the film is 0 ° as a reference line, and is represented by the angle on the side rotated in the clockwise direction. Among the obtained velocities in each direction, the largest pulse propagation velocity is defined as VMAX, and among the obtained velocities in each direction, the smallest pulse propagation velocity is defined as VMIN, and AI is obtained from these values.

The width (film-forming width) of the polyimide film of the present invention is not particularly limited, but is particularly limited to 1000 mm or more (for example, 1200 to 2500 mm), preferably 1500 mm or more (for example, 1700 to 2500 mm), and more preferably 2000 mm or more (for example). , 2000-2500 mm).

In the present invention, even in such a relatively wide film, the specific linear expansion coefficient and anisotropy index (AI value) as described above can be satisfied, and variations in dimensional change (heat shrinkage) and pieces after heat treatment can be satisfied. The elongation can be reduced.

The thickness (average thickness) of the polyimide film of the present invention is not particularly limited and can be appropriately selected depending on the intended use, for example, 1 μm or more (for example, 1 to 300 μm), preferably 2 to 200 μm, and more preferably 3 to 3. It may be about 150 μm (for example, 5 to 100 μm).

As described above, the polyimide film of the present invention has a small variation in dimensional change (heat shrinkage) in the film-forming width direction and a small elongation after heat treatment. Further, the variation in the dimensional change rate in the film forming width direction of the flexible metal laminated plate obtained by using the polyimide film of the present invention is small.

For example, the polyimide film of the present invention has a variation in the dimensional change rate in the film forming width direction before and after removing the metal foil of the flexible metal laminate, which is 0.05% or less, preferably 0.04% or less. May be good.

Further, in the polyimide film of the present invention, the difference in heat shrinkage at 200 ° C. in the width direction may be 0.05% or less, preferably 0.04% or less, and more preferably 0.02% or less.

The variation in the dimensional change rate and the difference in the heat shrinkage rate in the film width direction are, for example, within the range of a straight line connecting the two points by selecting two points 200 mm inside from both ends of the film forming width in the film width direction. Select one point within ± 200 mm of the central part on the straight line including the two points and any other two points, measure the dimensional change rate and heat shrinkage rate at at least these five points, and among the obtained measured values, It can be obtained as the difference between the maximum value and the minimum value.

Further, the polyimide film of the present invention has a width of 508 mm and a length of 6.5 m, and has a one-sided elongation (length of a in FIG. 1 described later) when treated at 200 ° C. for 30 minutes, which is 5 mm or less, preferably 4 mm or less. , More preferably 3.5 mm or less.

The film of the present invention is composed (or formed) of polyimide. The polyimide will be described below as well as the film manufacturing method.

[Manufacturing method of polyimide and polyimide film]
Polyimide (or polyamic acid) has an aromatic diamine component and an acid anhydride component as a polymerization component.

Specifically, when producing a polyimide (or polyimide film), first, a polyamic acid (polyimide precursor) solution is obtained by polymerizing an aromatic diamine component and an acid anhydride component in an organic solvent.

The aromatic diamine component usually contains at least para-phenylenediamine (PPD). The aromatic diamine component may contain a component other than paraphenylenediamine, and specific examples of the aromatic diamine component other than paraphenylenediamine include metaphenylenediamine, benzidine, paraxylylene diamine, 4,4'-. Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,5-diaminonaphthalene, Examples thereof include 3,3'-dimethoxybenzidine, 1,4-bis (3 methyl-5 aminophenyl) benzene and amide-forming derivatives thereof.
These may be used individually by 1 type, or may be used by mixing 2 or more types.
As the aromatic diamine component, a combination of para-phenylenediamine (PPD) and 4,4'-diaminodiphenyl ether and / or 3,4'-diaminodiphenyl ether (DPE) is preferable, and para-phenylenediamine (PPD) is particularly used. , 4,4'-Diaminodiphenyl ether and / or combination with 3,4'-diaminodiphenyl ether (DPE) is preferable, and in particular, a combination of para-phenylenediamine (PPD) and 4,4'-diaminodiphenyl ether (DPE). Is preferable.

When the aromatic diamine component contains paraphenylenediamine, the ratio of paraphenylenediamine to the aromatic diamine component is, for example, 20 mol% or more (for example, 25 to 100 mol%), preferably 30 mol% or more (for example, 31). ~ 80 mol%), more preferably 35 mol% or more (eg 37-70 mol%), and usually 30-50 mol% (eg 35-45 mol%).

When para-phenylenediamine (PPD) is combined with 4,4'-diaminodiphenyl ether and / or 3,4'-diaminodiphenyl ether (DPE), the ratio of these is PPD / DPE (molar ratio) = 80/20 ~ It may be about 30/70, preferably about 75/25 to 35/65 (for example, 70/30 to 35/65), and usually 60/40 to 30/70 (for example, 50/50 to 35/65). It may be preferably 45/55 to 37/63).

Examples of the acid anhydride component (or an amide-forming derivative of the acid) include pyromellitic acid, 3,3', 4,4'-diphenyltetracarboxylic acid, 2,3', 3,4'-diphenyltetracarboxylic acid. Acid, 3,3', 4,4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2, Examples thereof include anhydrides of aromatic tetracarboxylic acids such as 3,5,6-tetracarboxylic acids. These may be used alone or in combination of two or more. Among these, pyromellitic dianhydride (PMPA) and 3,3', 4,4'-diphenyltetracarboxylic dianhydride (BPDA) are preferable, and it is particularly preferable to combine them.

When the acid anhydride component contains BPDA, the ratio of BPDA to the acid anhydride component is, for example, 15 mol% or more (for example, 15 to 100 mol%), preferably 20 mol% or more (for example, 22 to 90 mol%). ), Preferably 25 mol% or more (eg, 28-80 mol%), more preferably 30 mol% or more (eg, 32-60 mol%), and usually 25-45 mol% (eg, 30). ~ 40 mol%).

When combining pyromellitic dianhydride (PMPA) and 3,3', 4,4'-diphenyltetracarboxylic dianhydride (BPDA), the ratio of these is PMPA / BPDA (molar ratio) = 90 / It may be about 10 to 20/80, preferably 85/15 to 30/70, more preferably 80/20 to 35/65 (for example, 75/25 to 40/60), and usually 70/30 to 50. It may be / 50 (for example, 70/30 to 55/45, preferably 69/31 to 60/40).

Examples of the organic solvent used for forming the polyamic acid solution include sulfoxide-based solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide-based solvents such as N, N-dimethylformamide and N, N-diethylformamide, and N, N-. Acetamide solvents such as dimethylacetamide, N, N-diethylacetamide, pyroridone solvents such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, phenol, o-, m-, or p-cresol, xylenol. , Phenolic solvents such as halogenated phenol and catechol, or aprotonic polar solvents such as hexamethylphospholamide and γ-butyrolactone, and it is desirable to use these alone or as a mixture using two or more kinds. However, it is also possible to use aromatic hydrocarbons such as xylene and toluene.

The polymerization method may be any known method. For example, (1) first put the entire amount of the aromatic diamine component in the solvent, and then add the acid anhydride component to the total amount of the aromatic diamine component (equal molar). A method of polymerizing in addition to.
(2) A method in which the entire amount of the acid anhydride component is first put into a solvent, and then the aromatic diamine component is added so as to be equivalent to the acid anhydride component for polymerization.
(3) After putting one aromatic diamine component (a1) in a solvent, mix for the time required for the reaction at a ratio of one acid anhydride component (b1) to 95 to 105 mol% with respect to the reaction component. After that, the other aromatic diamine component (a2) is added, and then the other acid anhydride component (b2) is adjusted so that the total aromatic diamine component and the total acid anhydride component are approximately equivalent. A method of adding and polymerizing.
(4) After putting one acid anhydride component (b1) in a solvent, mix for the time required for the reaction at a ratio of one aromatic diamine component (a1) to 95 to 105 mol% with respect to the reaction component. After that, the other acid anhydride component (b2) is added, and then the other aromatic diamine component (a2) is added so that the total aromatic diamine component and the total acid anhydride component are approximately equivalent. And polymerize.
(5) One aromatic diamine component and an acid anhydride component are reacted in an excess in a solvent to prepare a polyamic acid solution (A), and the other aromatic diamine component is prepared in another solvent. And the acid anhydride component are reacted so that either one becomes excessive to prepare a polyamic acid solution (B). A method of mixing each of the polyamic acid solutions (A) and (B) thus obtained to complete the polymerization. At this time, if the aromatic diamine component is excessive when preparing the polyamic acid solution (A), the acid anhydride component is excessive in the polyamic acid solution (B) and the acid anhydride component is excessive in the polyamic acid solution (A). In the case of, the aromatic diamine component is excessive in the polyamic acid solution (B), the polyamic acid solutions (A) and (B) are mixed, and the total aromatic diamine component and the total acid anhydride component used in these reactions are mixed. Adjust so that they are almost equivalent. The polymerization method is not limited to these, and other known methods may be used.

The polyamic acid solution is a chemically inactive organic filler such as titanium oxide, fine silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, polyimide filler, or an inorganic filler, as necessary to obtain the slipperiness of the film. It may contain a filler or the like.

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

Next, a method for producing the polyimide film will be described. The film formation (manufacturing) of the polyimide film is carried out, for example, through a step (1) of cyclizing a polyamic acid solution to obtain a gel film and a step (2) of heating (and desolving) the obtained gel film. Obtainable. In addition, drying and imidization proceed by the heat treatment.

In the step (1), the method for ring-forming the polyamic acid solution is not particularly limited, but specifically, (i) the polyamic acid solution is cast into a film and thermally dehydrated and cyclized to form a gel film. (Thermal ring closure method) or (ii) A cyclization catalyst and a conversion agent (dehydrating agent) are mixed with a polyamic acid solution and chemically decyclized to prepare a gel film, and the gel film is heated by heating. Examples thereof include a method for obtaining (chemical ring closure method), and the latter method is particularly preferable. The polyamic acid solution can contain a gelation retarder and the like. The gelation retarder is not particularly limited, and acetylacetone or the like can be used.

Examples of the cyclization catalyst include amines such as aliphatic tertiary amines (trimethylamine, triethylenediamine, etc.), aromatic tertiary amines (dimethylaniline, etc.), heterocyclic tertiary amines (eg, isoquinoline, pyridine, etc.). (Β-picoline, etc.) and the like. These may be used individually by 1 type, or may be used by mixing 2 or more types. Of these, heterocyclic tertiary amines such as β-picoline are preferred.

Examples of the dehydrating agent include acid anhydrides, for example, aliphatic carboxylic acid anhydrides (for example, acetic anhydride, propionic anhydride, butyric anhydride, etc.), aromatic carboxylic acid anhydrides (for example, benzoic anhydride, etc.) and the like. .. These may be used individually by 1 type, or may be used by mixing 2 or more types. Among these, acetic anhydride and / or benzoic anhydride are preferable, and acetic anhydride is particularly preferable.

The amounts of the cyclization catalyst and the dehydrating agent used are not particularly limited, but are, for example, 1 mol or more (for example, 1.5) with respect to 1 mol of the amide group (or carboxyl group) of the polyamic acid (or polyamic acid). It may be about 10 mol), preferably 2 mol or more (for example, 2.2 to 8 mol), more preferably 2.5 mol or more (for example, 2.7 to 5 mol), and usually 2 to 4 mol. It may be about mol (for example, 2.5 to 3.3 mol).

A gel film (a gel film having self-supporting property) is usually obtained by casting (coating) a polyamic acid solution (particularly a polyamic acid solution in which a cyclization catalyst and a conversion agent are mixed) on a support and partially drying the gel film. And can be obtained by curing (imidization).

More specifically, the gel film is formed by casting a polyamic acid solution from a mouthpiece with a slit onto a support to form a film, and receiving heat from the support, hot air, or a heat source such as an electric heater. , The ring-closing reaction is carried out by heating, and the volatile components such as the liberated organic solvent are dried to form a gel film having self-supporting property, and then the gel film may be peeled off from the support.

The support is not particularly limited, and examples thereof include a rotating drum made of metal (for example, stainless steel), an endless belt, and the like. The temperature of the support is not particularly limited and may be, for example, 30 to 200 ° C., preferably 40 to 150 ° C., more preferably 50 to 120 ° C., particularly 70 to 100 ° C. (for example, 75 to 95 ° C.). ) May be the case.

The temperature of the support can be controlled by (i) a liquid or gas heat medium, (ii) radiant heat from an electric heater or the like.

The imidization rate of the gel film (gel film to be subjected to heat treatment, gel film peeled from the support) is, for example, 50 to 80%, preferably 52 to 78%, and more preferably 55 to 75% (for example, 57 to 57 to). It may be about 73%).

Note that the imidization ratio is represented by the following formula determined by the ratio of the peak height of 1375 cm ^-1 and 1500 cm ^-1 using FT-IR.

Imidization rate (%) = A / B × 100
[In the formula, A (1375 cm peak height of ^-1 of the measurement target film) / (the peak of 1500 cm ^-1 of the height of the measurement target film), B is the peak of 1375 cm ^-1 of the polyimide film comprising (reference Height) / (peak height of 1500 cm ^-1 of the reference film) is shown. ]

By setting the imidization ratio of the gel film in the above range, the polyimide film of the present invention can be easily obtained efficiently.

In step (2), the gel film is heated [and dried (desolventized)]. Usually, the step (2) may include a step of performing heat treatment (and drying) by passing the gel film through a heating furnace (such as a tenter heating path) while grasping both ends in the width direction of the gel film.

Specifically, the gel film peeled from the support is not particularly limited, but usually, the gel film may be stretched in the transport direction while regulating the traveling speed by a rotating roll. Stretching in the transport direction may be carried out at a temperature of 140 ° C. or lower. The draw ratio (MDX) is usually 1.05 to 1.9 times, preferably 1.1 to 1.6 times, and more preferably 1.1 to 1.5 times (for example, 1.15). ~ 1.3 times).

Further, even if the gel film (particularly the gel film stretched in the transport direction) is introduced into the tenter device, both ends in the width direction are gripped by the tenter clip, and the gel film is stretched in the width method while traveling together with the tenter clip. Good.

Stretching in the width direction may be carried out at a temperature of 200 ° C. or higher. The stretch ratio (TDX) may be, for example, 1.1 to 1.5 times that of MDX, preferably 1.2 to 1.45 times. The specific draw ratio (TDX) is, for example, 1.1 to 2 times, preferably 1.3 to 1.8 times, more preferably 1.35 to 1.7 times (for example, 1.4 to 1. 6 times).

The polyimide film thus obtained can be obtained. The obtained polyimide film may be further subjected to an annealing treatment or an easy-adhesion treatment (for example, an electric treatment such as a corona treatment or a plasma treatment or a blast treatment).

[Flexible metal laminate]
The polyimide film of the present invention can be used, for example, as an insulating film for a flexible metal laminated board (flexible printed wiring board).

Therefore, the present invention includes a flexible metal laminate provided with the polyimide film of the present invention. Such a flexible metal laminate usually includes a polyimide film and a metal foil.

The type of metal constituting the metal foil is not particularly limited, and examples thereof include copper and copper alloys, stainless steel and its alloys, nickel and nickel alloys (including 42 alloys), aluminum and aluminum alloys, and the like. Copper and copper alloys are preferred. Further, those having a rust preventive layer, a heat resistant layer (for example, plating treatment of chromium, zinc, etc.), a silane coupling agent, or the like formed on these metal surfaces can also be used. Preferably, it contains at least one component of copper and / or nickel, zinc, iron, chromium, cobalt, molybdenum, tungsten, vanadium, beryllium, titanium, tin, manganese, aluminum, phosphorus, silicon and the like and copper. Copper alloys, which are preferred for circuit processing. A particularly desirable metal foil is a copper foil formed by rolling or electroplating, and the thickness thereof is preferably 3 to 150 μm, more preferably 3 to 35 μm.

The metal foil may not have been subjected to any roughening treatment on both sides, or may be roughened on one side or both sides.

The flexible metal laminate is not particularly limited in the form of lamination as long as it includes the polyimide film and the metal foil. For example, the polyimide film and the metal foil may be directly laminated, and an adhesive layer (adhesive) may be provided. The polyimide film and the metal foil may be laminated (bonded) via the agent layer).

The adhesive component constituting the adhesive layer is not particularly limited, and may be, for example, a thermosetting resin or a thermoplastic resin. In particular, the adhesive layer may be made of thermoplastic polyimide.

Therefore, the present invention also includes an adhesive film (laminated film) having a thermoplastic polyimide layer (adhesive layer composed of thermoplastic polyimide) on at least one side of the polyimide film.

The thermoplastic polyimide is obtained by imidizing the precursor polyamic acid. The precursor of the thermoplastic polyimide is not particularly limited, and any known polyamic acid can be used. Also, known raw materials, reaction conditions and the like can be used for the production thereof. Inorganic or organic fillers may be added as needed.

The glass transition temperature of the thermoplastic polyimide may be, for example, about 150 ° C. to 350 ° C.

The adhesive film can be obtained by providing an adhesive layer containing a thermoplastic polyimide on at least one side of the polyimide film (non-thermoplastic polyimide film). As a specific manufacturing method thereof, a method of forming an adhesive layer on a polyimide film to be a base film, a method of forming an adhesive layer into a sheet shape, and a method of bonding the adhesive layer to the polyimide film are preferably exemplified. .. Of these, when the former method is adopted, if the polyamic acid, which is a precursor of the thermoplastic polyimide contained in the adhesive layer, is completely imidized, the solubility in an organic solvent may decrease. It may be difficult to provide the adhesive layer on the polyimide film. Therefore, from the above viewpoint, it is more preferable to take a procedure of preparing a solution containing a polyamic acid which is a precursor of thermoplastic polyimide, applying the solution to the base film, and then imidizing the solution.

The method of casting and applying the polyamic acid solution to the polyimide film is not particularly limited, and existing methods such as a die coater, a reverse coater, and a blade coater can be used. When the adhesive layer is continuously formed, the effect of the invention becomes remarkable. That is, it is a method in which the polyimide film obtained as described above is wound up, unwound, and a solution containing polyamic acid, which is a precursor of thermoplastic polyimide, is continuously applied. In addition, the polyamic acid solution may contain other materials such as fillers, depending on the intended use. Further, the thickness structure of each layer of the heat-resistant adhesive film may be appropriately adjusted so as to have a total thickness according to the application.

As the imidization method, either a thermal imidization method or a chemical imidization method can be used. In any of the imidization procedures, heating is performed in order to promote imidization efficiently, and the temperature at that time is in the range of (glass transition temperature of thermoplastic polyimide -100 ° C) to (glass transition temperature + 200 ° C). It is preferable to set it in the range of (glass transition temperature of thermoplastic polyimide −50 ° C.) to (glass transition temperature + 150 ° C.). Since imidization is more likely to occur at a higher heating temperature, the imidization rate can be increased, which is preferable in terms of productivity. However, if it is too high, the thermoplastic polyimide may cause thermal decomposition. On the other hand, if the heating temperature is too low, imidization is difficult to proceed even with chemical imidization, and the time required for the imidization step becomes long.

The imidization time is not particularly limited as long as it takes a sufficient time to substantially complete imidization and drying.

The thickness of the thermoplastic polyimide is preferably 0.1 μm or more and 30 μm or less, and more preferably 0.5 μm or more and 20 μm or less.

As a method of heat-bonding the non-thermoplastic polyimide and the metal, a polyamic acid and / or a polyimide solution, which is a precursor of the thermoplastic polyimide, is applied to the non-thermoplastic polyimide film and then bonded to the metal or preheated to the metal. After forming the plastic polyimide by the same method, there is a method of laminating with a non-thermoplastic polyimide film, and a heat pressing method and / or a continuous laminating method can be used for laminating. As a heat pressing method, for example, it can be manufactured by superimposing a metal foil cut out to a predetermined size of a press machine and polyimide and thermocompression bonding by a heat press.

The continuous laminating method is not particularly limited, but for example, there is a method of sandwiching and laminating between rolls. As this roll, a metal roll, a rubber roll and the like can be used. There are no restrictions on the material, but steel or stainless steel is used as the metal roll. It is preferable to use a treatment roll having an increased surface hardness such as hard chrome plating or tungsten carbide on the surface. As the rubber roll, it is preferable to use heat-resistant silicone rubber or fluorine-based rubber on the surface of the metal roll.

In addition, two upper and lower metal rolls called belt laminates are made into one set, and two seamless stainless steel belts on the upper and lower sides are arranged between the upper and lower rolls in which one or more sets are arranged in series, and the belts are arranged by the metal rolls. Continuous lamination may be performed by pressurizing and further heating with a metal roll or other heat source.

The lamination temperature is preferably in the temperature range of 200 to 400 ° C. It is also preferable to heat-anneal after heat pressing and / or continuous laminating.

The flexible metal laminated plate of the present invention can be used as a flexible wiring board on which various miniaturized and high-density parts are mounted by etching a metal foil to form a desired pattern wiring. Of course, the use of the present invention is not limited to this, and it goes without saying that a laminate containing a metal foil can be used for various purposes.

The present invention includes various combinations of the above configurations within the technical scope of the present invention as long as the effects of the present invention are exhibited.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples, and many modifications are made in the art within the technical idea of the present invention. It is possible by a person with ordinary knowledge.

The method for measuring various characteristics in the present invention will be described below.

(Immidization rate)
The imidization ratio represents the relative presence of the imide group of the target film with respect to the polyimide film of the product.
Using FT-IR is represented by the following formula determined by the ratio of the peak height of 1375 cm ^-1 and 1500 cm ^-1.

Imidization rate (%) = A / B × 100
[In the formula, A (1375 cm peak height of ^-1 of the measurement target film) / (the peak of 1500 cm ^-1 of the height of the measurement target film), B is the peak of 1375 cm ^-1 of the polyimide film comprising (reference Height) / (peak height of 1500 cm ^-1 of the reference film) is shown. ]

As the reference polyimide film, a film that had been dried and heat-treated was used.

(AI value)
The propagation velocity V of the ultrasonic pulse was measured using the following SST-2500 (Sonic Sheet Tester) manufactured by Nomura Shoji. When SST-2500 is used, the ultrasonic velocity in 16 directions is automatically measured in 11.25 ° increments from 0 to 180 degrees in the plane direction of the film (0 degrees is parallel to the MD direction). Among the obtained velocities in each direction, the anisotropy index (AI) represented by the formula 1 can be obtained from the maximum velocity (MAX) and the minimum velocity (MIN). Using the films obtained in the following Examples and Comparative Examples, measurements were carried out in the following measurement ranges, respectively.

(Equation 1): AI = (VMAX ^ 2-VMIN ^ 2) / (VMAX ^ 2 + VMIN ^ 2)
(In the equation, VMAX ^ 2 indicates the square of the maximum value of the pulse propagation velocity, and VMIN ^ 2 indicates the square of the minimum value of the pulse propagation velocity.)

Select two points that are 200 mm inside from both ends of the film forming width in the film width direction (TD direction), and within the range of the straight line connecting the two points, one point within ± 200 mm of the central part on the straight line including the two points. And select any 2 points and measure at least these 5 points.
The AI value was measured at at least 5 points on a straight line in the film width direction, and the largest AI value (AI value MAX) among the measurement points was shown in the table. That is, the largest estimation of the anisotropy in the film width direction is the AI value MAX (by showing the AI value MAX, it can be seen that the AI value is equal to or less than the AI value MAX over the entire width of the film). If the AI value MAX (or the AI value over the entire width) is large, the one-sided elongation after the film heat treatment deteriorates, and defects such as wrinkles occur during winding. Further, the dimensional change rate of the flexible metal laminated plate obtained by using the polyimide film before and after the removal of the metal foil varies in the film forming width direction.

(Coefficient of thermal expansion (CTE) and variation of CTE in film width direction)
Using TMA-50 (manufactured by Shimadzu Corporation), measurement was performed in the following measurement range under the conditions of a measurement temperature range of 50 to 200 ° C. and a heating rate of 10 ° C./min.

Select two points that are 200 mm inside from both ends of the film forming width in the film width direction (TD direction), and within the range of the straight line connecting the two points, one point within ± 200 mm of the central part on the straight line including the two points. And further, any two points were selected, and at least these five points were measured.
Then, from the values at each measurement point, CTE (ppm / ° C.) in the MD direction and CTE (ppm / ° C.) in the TD direction were obtained as average values.
In addition, among the values at each measurement point, for each of the CTE (ppm / ° C) in the MD direction and the CTE (ppm / ° C) in the TD direction, the difference between the maximum value and the minimum value is the MD-CTE difference in the width direction. ppm / ° C.) and TD-CTE difference in the width direction (ppm / ° C.).

(Variation of heat shrinkage in the film width direction)
The film size (L1) was measured after cutting out to 200 mm in the film machine transport direction (MD direction) and 200 mm in the film width direction (TD direction) and leaving the film in a room adjusted to 25 ° C. and 60% RH for 2 days. Subsequently, after heating at 200 ° C. for 60 minutes, the film size (L2) after being left in a room adjusted to 25 ° C. and 60 RH% again for 2 days was measured, and the heat shrinkage rate was determined by the following formula.

Heat shrinkage rate (%) =-{(L2-L1) / L1} × 100
For the variation in the heat shrinkage in the film width direction, select two points that are 200 mm inside from both ends of the film forming width in the film width direction (TD direction), and the two points are within the range of the straight line connecting the two points. One point within ± 200 mm of the central part on the straight line including, and any two points were selected, and the film cut out containing at least each of these five points was measured, and the obtained measured value (heat) was obtained. The shrinkage rate) was calculated as the difference between the maximum value and the minimum value.

(Variation of dimensional change rate in the film width direction)
Based on JIS C6481 5.16, four holes were formed on the center and diagonal of the adhesive film of the sample, and the distance of each hole from the center was measured. Next, after the copper foil was attached and the etching step was performed to remove the metal foil from the flexible metal laminated plate, the distances between the four holes were measured again in the same manner as before the etching step. Let D1 be the measured value of the distance of each hole before removing the metal foil, and D2 be the measured value of the distance of each hole after removing the metal foil. I asked.

Dimensional change rate (%) = {(D2-D1) / D1} x 100
For such a dimensional change rate, select two points that are 200 mm inside from both ends of the film forming width in the film width direction (TD direction), and within the range of the straight line connecting the two points, on a straight line including the two points. One point within ± 200 mm of the central portion and two more arbitrary points were selected and measured at least these five points, and the difference between the maximum value and the minimum value was defined as the variation in the dimensional change rate in the film width direction.

The metal laminate was prepared by laminating an adhesive layer (thermoplastic polyimide layer) on one side of a polyimide film and then laminating a rolled copper anchor on the adhesive layer side. Specifically, a polyamic acid solution of thermoplastic polyimide [1,3-bis- (4-aminophenoxy) benzene was added to the solvent dimethylacetamide, and the mixture was stirred until dissolved. Then, 4,4'-dioxydiphthalic anhydride was added, and the polyamic acid solution obtained by stirring] was applied so as to have a thickness of 2 μm after drying, and the film was applied at 150 ° C. for 10 minutes at 350 ° C. It was thermally imidized for 1 minute (preparation of adhesive film). Then, a copper foil was bonded to the thermoplastic polyimide side at 350 ° C./30 minutes to prepare a flexible metal laminated plate.

(One-sided elongation value)
The one-sided elongation value (mm) shown in FIG. 1 (a) was measured by the following procedure.
Slit the polyimide film into strips with a width of 508 mm and a length of 6.5 m.
This strip-shaped film is heated in a hot air oven at 200 ° C. for 30 minutes without applying an external force, and then removed from the oven.
Spread the sample on a flat floor and measure the maximum distance (one-sided elongation) between the curved arc and the string when they are in close contact with each other.

(Examples 1 to 5)
Piromellitic acid dianhydride (PMPA, molecular weight 218.12) / 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA, molecular weight 294.22) / 4,4'-diaminodiphenyl ether (DPE) , Molecular weight 200.24) / paraphenylenediamine (PPD, molecular weight 108.14) was prepared at a molar ratio of 65/35/60/40, and polymerized in 20% by weight in DMAC (N, N-dimethylacetamide). Then, a polyamic acid solution having a molecular weight of 3500 at 25 ° C. was obtained.

After adding β-picoline and acetic anhydride to this polyamide solution so that the molar ratio to the polyamic acid is 3.0, the polyimide is poured from the base onto a stainless steel support at 90 ° C. and has self-supporting properties. A gel film was obtained.

This gel film was peeled off from the support, transported via a nip roll, and vertically stretched. After longitudinal stretching, both ends of the film were grasped, and the film was dried in a tenter while being laterally stretched. After drying, heat treatment was carried out using an electric heater to obtain a polyimide film.

The thickness of the polyimide film was changed by controlling the ratio of the base ejection speed / support rotation speed to obtain a polyimide film having an average thickness of 7.5 to 38 μm.

(Reference example 1)
Piromellitic acid dianhydride (PMPA, molecular weight 218.12) / 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA, molecular weight 294.22) / 4,4'-diaminodiphenyl ether (DPE) , Molecular weight 200.24) / paraphenylenediamine (PPD, molecular weight 108.14) was prepared at a molar ratio of 75/25/60/40, and polymerized in 20% by weight in DMAC (N, N-dimethylacetamide). Then, a polyamic acid solution having a molecular weight of 3500 at 25 ° C. was obtained.

After adding β-picoline and acetic anhydride to this polyamide solution so that the molar ratio to the polyamic acid is 3.3, the film is cast on a stainless steel support at 75 ° C. to provide a self-supporting polyimide gel film. Got

This gel film was peeled off from the support, transported via a nip roll, and vertically stretched. After longitudinal stretching, both ends of the film were grasped, and the film was dried in a tenter while being laterally stretched. After drying, heat treatment was carried out using an electric heater to obtain a polyimide film.

(Reference example 2)
Piromellitic acid dianhydride (PMPA, molecular weight 218.12) / 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA, molecular weight 294.22) / 4,4'-diaminodiphenyl ether (DPE) , Molecular weight 200.24) / paraphenylenediamine (PPD, molecular weight 108.14) was prepared at a molar ratio of 75/25/60/40, and polymerized in 20% by weight in DMAC (N, N-dimethylacetamide). Then, a polyamic acid solution having a molecular weight of 3500 at 25 ° C. was obtained.

After adding β-picoline and acetic anhydride to this polyamide solution so that the molar ratio to polyamic acid is 2.8, the film is cast on a stainless steel support at 75 ° C. and has self-supporting polyimide gel film. Got

This gel film was peeled off from the support, transported via a nip roll, and vertically stretched. After longitudinal stretching, both ends of the film were grasped, and the film was dried in a tenter while being laterally stretched. After drying, heat treatment was carried out using an electric heater to obtain a polyimide film.

(Reference example 3)
Piromellitic acid dianhydride (PMPA, molecular weight 218.12) / 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA, molecular weight 294.22) / 4,4'-diaminodiphenyl ether (DPE) , Molecular weight 200.24) / paraphenylenediamine (PPD, molecular weight 108.14) was prepared at a molar ratio of 75/25/60/40, and polymerized in 20% by weight in DMAC (N, N-dimethylacetamide). Then, a polyamic acid solution having a molecular weight of 3500 at 25 ° C. was obtained.

After adding β-picoline and acetic anhydride to this polyamide solution so that the molar ratio to the polyamic acid is 2.5, the film is cast on a stainless steel support at 75 ° C. to provide a self-supporting polyimide gel film. Got

This gel film was peeled off from the support, transported via a nip roll, and vertically stretched. After longitudinal stretching, both ends of the film were grasped, and the film was dried in a tenter while being laterally stretched. After drying, heat treatment was carried out using an electric heater to obtain a polyimide film.

(Reference example 4)
Piromellitic acid dianhydride (PMPA, molecular weight 218.12) / 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA, molecular weight 294.22) / 4,4'-diaminodiphenyl ether (DPE) , Molecular weight 200.24) / paraphenylenediamine (PPD, molecular weight 108.14) was prepared at a molar ratio of 65/35/82/18, and polymerized in 20% by weight in DMAC (N, N-dimethylacetamide). Then, a polyamic acid solution having a molecular weight of 3500 at 25 ° C. was obtained.

After adding β-picoline and acetic anhydride to this polyamide solution so that the molar ratio to the polyamic acid is 2.8, the film is cast on a stainless steel support at 95 ° C. to provide a self-supporting polyimide gel film. Got

This gel film was peeled off from the support, transported via a nip roll, and vertically stretched. After longitudinal stretching, both ends of the film were grasped, and the film was dried in a tenter while being laterally stretched. After drying, heat treatment was carried out using an electric heater to obtain a polyimide film.

Table 1 below summarizes the composition of polyimide, the conditions for producing a polyimide film, and various physical properties of the polyimide film.

From the above results, it was confirmed that in the polyimide film of the present invention, the variation in the dimensional change in the film width direction was small and the one-sided elongation was also small.

The polyimide film of the present invention is useful for flexible printed wiring boards and the like.

1: Strip-shaped film 2: Film edge a: One-sided elongation value

Claims (9)

Both the coefficient of linear expansion αMD in the transport direction (MD) and the coefficient of linear expansion αTD in the width direction (TD) of the film are 7 ppm / ° C. or less, and are expressed by the following formula when the propagation speed V of the ultrasonic pulse is measured. A polyimide film having an anisotropy index AI value of 15 or less over the entire width.
AI = (VMAX ^ 2-VMIN ^ 2) / (VMAX ^ 2 + VMIN ^ 2)
(In the equation, VMAX ^ 2 indicates the square of the maximum value of the pulse propagation velocity, and VMIN ^ 2 indicates the square of the minimum value of the pulse propagation velocity.)
However, in the above formula, VMAX and VMIN mean that they are the maximum speed and the minimum speed, respectively, among the ultrasonic speeds measured in 16 directions in 11.25 ° increments with respect to the plane direction of the film from 0 to 180 degrees. And
If the AI value is 15 or less over the entire width, select two points that are 200 mm inside from both ends of the film forming width in the film width direction, and within the range of the straight line connecting the two points, on the straight line including the two points. It means that the AI value measured at these 5 points is 15 or less by selecting 1 point within ± 200 mm of the central part and 2 points arbitrarily. The polyimide film according to claim 1, wherein the film-forming width is 1000 mm or more, and the difference in linear expansion coefficient of αMD in the film width direction is 2 ppm / ° C. or less.
However, for the difference in the linear expansion coefficient in the film width direction, select two points that are 200 mm inward from both ends of the film forming width in the film width direction, and within the range of the straight line connecting the two points, on a straight line including the two points. The linear expansion coefficient is measured at one point within ± 200 mm of the central portion of the above and an arbitrary two points, and is obtained as the difference between the maximum value and the minimum value among the obtained measured values. The polyimide film according to claim 1 or 2, wherein the film-forming width is 1000 mm or more, and the difference in linear expansion coefficient of αTD in the film width direction is 2 ppm / ° C. or less.
However, for the difference in the linear expansion coefficient in the film width direction, select two points that are 200 mm inward from both ends of the film forming width in the film width direction, and within the range of the straight line connecting the two points, on a straight line including the two points. The linear expansion coefficient is measured at one point within ± 200 mm of the central portion of the above and an arbitrary two points, and is obtained as the difference between the maximum value and the minimum value among the obtained measured values. Polyimide film, an aromatic diamine component comprising p-phenylenediamine, pyromellitic dianhydride and 3,3 ', 4,4'-biphenyl from tetracarboxylic acid group consisting of anhydrides of one or more selected The polyimide film according to any one of claims 1 to 3, which is composed of a polyimide containing an acid anhydride component as a polymerization component. A polyimide film obtained by using an aromatic diamine component containing para-phenylenediamine and an acid anhydride component, using TMA-50 manufactured by Shimadzu Corporation, measuring temperature range: 50 to 200 ° C, heating rate: 10 ° C. Thermal expansion coefficient α of the film in the machine transport direction (MD) measured under the condition of / minute _MD Is in the range of 2.0 ppm / ° C or higher and lower than 10.0 ppm / ° C, and the coefficient of thermal expansion α in the width direction (TD) _TD Is in the range of -2.0 ppm / ° C or higher and 3.5 ppm / ° C or lower, | α _MD ｜ ≧ ｜ α _TD The polyimide film according to any one of claims 1 to 4, excluding the polyimide film satisfying the relationship of | × 2.0. The polyimide film according to any one of claims 1 to 5, wherein the polyimide film has a width of 508 mm and a length of 6.5 m, and has a one-sided elongation of 4 mm or less when treated at 200 ° C. for 30 minutes. A self-supporting gel film was prepared by casting a polyimide precursor solution on a support and partially drying and curing the gel film, and passing the gel film through a heating furnace while grasping both ends in the width direction to dry the gel film. The method for producing a polyimide film according to any one of claims 1 to 6 , wherein the polyimide film is subjected to heat treatment. The production method according to claim 7 , wherein the gel film has an imidization ratio of 55 to 75%. A flexible metal laminated plate provided with the polyimide film according to any one of claims 1 to 6 and a metal foil.