JP4525337B2 - Manufacturing method of slippery polyimide film - Google Patents

Description

  The present invention produces a polyimide film having excellent slipperiness by treating the film surface with an abrasive tape to generate streaky irregularities on the film surface, and by using this, a multilayer substrate is bonded. The present invention relates to a method for producing an easy-sliding polyimide film that can improve the releasability of the hinge portion.

  Polyimide films are widely used in applications such as base films for flexible circuit boards laminated with a metal foil such as a copper foil because they are excellent in insulation, heat resistance, electrical properties, and mechanical properties.

  And one of the important required characteristics when a polyimide film is used for these uses is the slipperiness of the film surface. Polyimide film with a completely smooth film surface has poor slipperiness and has a large coefficient of friction with a support (for example, a roll) during transportation in the film processing process, causing wrinkles or winding around the roll. When producing a flexible printed circuit board, troubles such as inability to laminate with copper foil may occur.

  Furthermore, when a multilayer substrate is laminated by a hot press using a bonding sheet, the films are in close contact with each other under the influence of the hot press on the hinge part that serves to bond the substrates together. In addition to the trouble of peeling off, there may be problems such as “sounding” due to rubbing.

Conventionally, surface roughening has been cited as a method for imparting easy slipping to the polyimide film surface, and various methods have existed. For example, there has been known a method (for example, see Patent Document 1 and Patent Document 2) of adding easy slipperiness by mixing a polyimide film with a filler such as calcium phosphate and generating fine protrusions on the film surface. Also, there is a method for imparting easy lubricity by treating the polyimide film surface with an alkaline solution and roughening the surface by utilizing the fact that polyimide is soluble in alkali (for example, see Patent Document 3). It was known. Problems such as the inability to laminate with copper foil that occurred during the film processing process have been solved by these methods, but problems such as the film sticking to each other at the hinge part and problems such as "sounding" occur. As a result, further film surface roughening was required.
JP-A-62-68852 JP 2002-256085 A JP-A-6-313055

  The present invention has been achieved as a result of studying the solution of the problems in the prior art described above as an issue.

  Therefore, an object of the present invention is to reduce the adhesion between films at the hinge portion when a multilayer substrate is laminated by a hot press, and to easily solve the “sounding” trouble caused by the friction between films. It is providing the manufacturing method of the polyimide film excellent in lubricity.

In order to achieve the above object, the manufacturing method of the slippery polyimide film of the present invention is such that when the surface of the polyimide film is treated with a polishing roll wound with a polishing tape , the film rotates in the direction opposite to the traveling direction of the film. By rubbing the film surface with a polishing roll, the height difference is 0.05 to 4.00 μm and the width is 0.1 to 10 μm in the range of 0.1 to 1000 lines / mm on the film surface. It is made to form by.

Furthermore, it is preferable that the method for producing a slippery polyimide film of the present invention includes the following (1) to (2) .
(1) The abrasive constituting the surface of the polishing tape is any of silicon carbide, aluminum oxide, chromium oxide, cerium oxide, and diamond particles.
(2) The particle size of the abrasive constituting the surface of the polishing tape is 0.1 to 100 μm.

  The present invention relates to a method for producing a polyimide film having excellent slipperiness by generating streak-like irregularities on the film surface by treating the film surface with an abrasive tape, and is obtained by using this production method. The polyimide film thus obtained has no adhesion between the films and the film is not rubbed during bending, and can be suitably used for the hinge portion of the flexible printed circuit board.

  The present invention will be described in detail below.

  First, as an abrasive tape to be used, for example, a type in which a PET film is used as a base and an abrasive is coated thereon is used. The thickness of the PET film as the base is preferably in the range of 25 to 75 μm because it is easy to handle. Examples of the abrasive include particles of silicon carbide, aluminum oxide, chromium oxide, cerium oxide, diamond, etc., and the particle size of the abrasive is preferably in the range of 0.1 to 100 μm depending on the degree of roughening, More preferably, it exists in the range of 1-50 micrometers. If the particle size is larger than this range, the film may be too rough, and mechanical properties such as strength may be impaired. If the particle size is smaller than this range, the effect of imparting the slipperiness of the film is lowered, which is not preferable.

  As a method for treating the film surface with the polishing tape of the present invention, as shown in FIGS.

  In FIG. 1, the polyimide film is fed from an unwinding roll 1 and wound around the winding roll 2 while rubbing the surface of the polishing roll 3 rotating in the direction opposite to the traveling direction. In FIG. 2, the polyimide film exiting the unwinding roll 1 is wound around the winding roll 2 while rubbing between the polishing roll 3 and the pressing roll 4 rotating in the opposite direction. The surface pressure at this time is preferably 1 to 10 kg / 500 mm. In FIG. 3, the polyimide film exiting the unwinding roll 1 is wound around the winding roll 2 while rubbing between two polishing rolls 3 and 3 ′ rotating in opposite directions. Here, if the surface pressure is increased, it becomes difficult to run the film. Therefore, the surface pressure is preferably set to 0.1 to 5 kg / 500 mm.

  When processing only one side of the film, it can be processed by the method shown in FIG. 1 or FIG. 2, but FIG. 2 can control the pressure when the polishing roll is brought into contact with the film, and can efficiently form unevenness. Since it can provide, it is preferable. When processing both surfaces of a film, it can obtain by processing like FIG. The tension applied to the film during these treatments is preferably adjusted in the range of 10 to 50 N / m, and the treatment speed is preferably adjusted in the range of 5 to 40 m / min.

  The polyimide film treated with the polishing tape preferably has a coefficient of static friction between the film surfaces measured according to JIS K-7125 of 0.1 to 0.7, and the film surface measured according to JIS B-0601. The roughness Rz is more preferably 0.8 to 3.0 μm, and these characteristics can be imparted by imparting streak-like irregularities on the film surface.

  Moreover, it is preferable to adjust the level difference of the stripe in the stripe-shaped unevenness to be imparted to the film surface to a range of 0.05 to 4.00 μm, and further, the width of the stripe-shaped unevenness is in the range of 0.1 to 10 μm. More preferably, it is more preferable to adjust the stripe-shaped unevenness in the range of 0.1 to 1000 / mm, thereby providing easy slipperiness to the film, and flexibility. After the hinge portion of the printed circuit board is formed, the films do not adhere to each other even under the influence of hot press, and problems such as noise can be prevented.

  The direction of the stripe-shaped unevenness is given along the direction parallel to the machine feed direction (MD) of the film, given along the direction parallel to the width direction (TD) of the film, and obliquely with respect to the machine feed direction. However, as shown in FIGS. 1 to 3, the method of applying along the machine feed direction (MD) of the film can be simplified most easily. Therefore, it is preferable.

  As for the other polishing method, a disc-shaped disk type may be used as the polishing tape, and this may be contacted while rotating on the film surface, so that streak-like irregularities may be formed in completely random directions.

  As an example of the polyimide film used in the present invention, a polyimide film produced from polymellitic acid obtained from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether, 3,3 ′, 4,4′-biphenyl Polyimide film produced from polyamic acid obtained from four components of tetracarboxylic dianhydride, pyromellitic dianhydride, p-phenylenediamine and 4,4′-diaminodiphenyl ether, pyromellitic dianhydride, 4, Polyimide film produced from 3 components of 4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether, 3 components of pyromellitic dianhydride, 4,4′-diaminodiphenyl ether and p-phenylenediamine Manufactured from polyamic acid obtained from Polyimide film prepared from polyamic acid obtained from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine, 3,3 ′, 4,4′-biphenyl And a polyimide film produced from a polyamic acid obtained from tetracarboxylic dianhydride and 4,4′-oxydianiline. The decyclization of polyamic acid to polyimide may be either a chemical ring closure method or a thermal ring closure method. Further, for the purpose of improving workability, it is possible to contain 10% by weight or less of an inorganic or organic additive.

  The thickness of the polyimide film of the present invention is preferably 3 to 200 μm. That is, if the thickness is less than 3 μm, it is difficult to maintain the shape, and if it exceeds 200 μm, the flexibility is insufficient, so that it is not suitable for flexible circuit board applications. In order to improve the dimensional stability of the polyimide film, it may be subjected to low heat shrinkage by annealing treatment or the like, or plasma treatment or the like may be performed to improve the adhesiveness.

  Thus, it is possible to provide a method for producing a slippery polyimide film that is excellent in slipperiness and that can improve the releasability of the hinge portion connecting the multilayer flexible plates.

The present invention will be described more specifically with reference to the following examples. In addition, each characteristic in an Example is the value measured with the following method.

[Friction coefficient (Static friction coefficient)]
It measured according to JIS K-7125. That is, using a slip coefficient measuring apparatus Slip Tester (manufactured by Technonez Co., Ltd.), the film processing surfaces are overlapped with each other, a 200 g weight is placed thereon, one side of the film is fixed, and the other side is fixed at 100 mm / min. Tensile and friction coefficients were measured.

[Measurement of surface roughness Rz of film]
Based on JIS B-0601 “Surface roughness”, measurement was performed with a laser microscope. That is, the surface of the film was photographed in the “SURFACE2” mode using a scanning laser microscope “1LM15W” manufactured by Lasertec Co., Ltd. and using a Nikon 50 × lens (CF Plan Apo 50 × / 0.95∞ / 0 EPI). After that, in SALT manufactured by Mitani Shoji Co., Ltd., the cut-off value when creating the roughness curve was set to 0.025 mm, and an area with an extended surface roughness of 0.01 mm ² or more was analyzed. The value of (point average roughness) was read.

[Difference in stripes]
Using the scanning laser microscope “1LM15W” manufactured by Lasertec Co., Ltd., using Nikon 50 × lens (CF Plan Apo 50 × / 0.95∞ / 0 EPI), the film surface was photographed in “SURFACE1” mode. The height difference of each streak was read from the chart obtained by analysis. The representative value is the average value of 5 points selected at random, and the maximum value is the maximum height by analysis with an area of 0.01 mm ² or more of the extended surface roughness in SALT after shooting in “SURFACE2” mode. Confirmed with Ry.

[Striped uneven width]
Using the scanning laser microscope “1LM15W” manufactured by Lasertec Co., Ltd., using Nikon 50 × lens (CF Plan Apo 50 × / 0.95∞ / 0 EPI), the film surface was photographed in “SURFACE1” mode. Analysis was performed, and the L key (left) and R key (right) were determined for each streak, and the streak width was read. The maximum width streak that can be seen in this field of view was used as a representative value.

[Number of stripe-shaped irregularities]
The surface of the film was photographed in “SURFACE1” mode using a scanning laser microscope “1LM15W” manufactured by Lasertec Co., Ltd. and using a Nikon 50 × lens (CF Plan Apo 50 × / 0.95∞ / 0 EPI). The number of streaks that were observed was counted.

[Evaluation of peelability after pressing]
About the polished film, 34 μm-thick rolled copper foil (Nikko Materials Co., Ltd.) is laminated on the surface opposite to the treated surface via the adhesive Pyralux LF100 (DuPont), and two sets of these are prepared. did. The film surfaces of this copper-clad laminate were put together and heated and pressed at 180 ° C. for 1 hour at a pressure of 10 MPa, and whether or not two sets of copper-clad laminates were peeled after pressing was evaluated. Those that were not peeled even when shaken lightly and held in close contact were judged as NG, those that had already been peeled off after being taken out, and those that peeled off easily by shaking lightly were judged as OK.

[Example 1]
A polyamic acid obtained from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether was mixed with about 0.1% by weight of calcium hydrogen phosphate having an average particle size of 1 μm, and a polyimide film having a thickness of 25 μm was manufactured. A polishing tape using silicon carbide having a particle size of 16 μm as an abrasive was used and processed at a running speed of 10 m / min as shown in FIG. The resulting film had a static friction coefficient of 0.44 and a surface roughness Rz of 1.20 μm. The height difference of streaks provided on the film surface was 0.62 μm, and the maximum height difference Ry was 1.40 μm. The maximum width of the stripe-shaped irregularities was 1.5 μm, and the number of the stripe-shaped irregularities was 230 / mm width. Regarding evaluation of peelability after pressing, the two sets of copper-clad laminates were peeled off and were OK.

[Example 2]
As a result of carrying out similarly to Example 1 except having processed with the travel speed of 10 m / min and the processing surface pressure of 3 kg / 500 mm in the manner of FIG. 2, the static friction coefficient of the obtained film was 0.40, and the surface roughness Rz was 1.68 μm, the height difference of the stripe-shaped irregularities imparted on the film surface is 1.18 μm, the maximum height difference Ry is 2.30 μm, the maximum width of the stripe-shaped irregularities is 6.8 μm, and the number of stripe-shaped irregularities is It was 215 pieces / mm width. Regarding evaluation of peelability after pressing, the two sets of copper-clad laminates were peeled off and were OK.

[Example 3]
A polyamic acid obtained from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether was mixed with about 0.1% by weight of calcium hydrogen phosphate having an average particle size of 1 μm, and a polyimide film having a thickness of 25 μm was manufactured. A polishing tape using silicon carbide having a particle size of 12 μm as an abrasive was used and treated in the same manner as in Example 1 as shown in FIG. The resulting film had a coefficient of static friction of 0.37 and a surface roughness Rz of 1.44 μm. The height difference of the streaks provided on the film surface was 0.32 μm, and the maximum height difference Ry was 1.24 μm. The maximum width of the stripe-like irregularities was 1.2 μm, and the number of stripe-like irregularities was 263 / mm width. Regarding evaluation of peelability after pressing, the two sets of copper-clad laminates were peeled off and were OK.

[Example 4]
As a result of carrying out similarly to Example 1 except having used the polyimide film of thickness 12.5 micrometers, the static friction coefficient of the obtained film is 0.47, surface roughness Rz is 1.16 micrometers, and on the film surface The height difference of the applied stripe-shaped unevenness was 0.72 μm, the maximum height difference Ry was 1.39 μm, the maximum width of the stripe-shaped unevenness was 1.6 μm, and the number of the stripe-shaped unevenness was 214 / mm width. Regarding evaluation of peelability after pressing, the two sets of copper-clad laminates were peeled off and were OK.

[Example 5]
A polyimide film having a thickness of 12.5 μm was used, and the same procedure as in Example 1 was conducted except that the film was processed at a running speed of 10 m / min and a treatment surface pressure of 3 kg / 500 mm as shown in FIG. The static friction coefficient is 0.40, the surface roughness Rz is 1.81 μm, the height difference of the stripe-shaped unevenness imparted on the film surface is 1.51 μm, the maximum height difference Ry is 2.18 μm, and the line-shaped unevenness The maximum width was 5.4 μm, and the number of stripe-shaped irregularities was 221 / mm width. Regarding evaluation of peelability after pressing, the two sets of copper-clad laminates were peeled off and were OK.

[Example 6]
Polyamic acid obtained from 100% by mole of pyromellitic dianhydride, 50% by mole of 4,4′-diaminodiphenyl ether and 50% by mole of 3,4′-diaminodiphenyl ether contains about 0 calcium phosphate with an average particle diameter of 1 μm. 1% by weight was mixed, and the manufactured polyimide film having a thickness of 25 μm was treated in the same manner as in Example 1 using a polishing tape using silicon carbide having a particle size of 16 μm as an abrasive. The resulting film had a static friction coefficient of 0.41 and a surface roughness Rz of 1.20 μm. The height difference of streaks provided on the film surface was 0.58 μm, and the maximum height difference Ry was 1.33 μm. The maximum width of the stripe-shaped irregularities was 1.8 μm, and the number of stripe-shaped irregularities was 212 / mm width. Regarding evaluation of peelability after pressing, the two sets of copper-clad laminates were peeled off and were OK.

[Example 7]
From 70 mol% of pyromellitic dianhydride, 30 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 80 mol% of 4,4′-diaminodiphenyl ether, and 20 mol% of paraphenylenediamine. About 0.1% by weight of calcium hydrogen phosphate having an average particle diameter of 1 μm is mixed in the resulting polyamic acid, and a polishing tape using silicon carbide having a particle diameter of 16 μm as an abrasive material is used for a polyimide film having a thickness of 25 μm. In the same manner as in Example 1, the processing was performed as shown in FIG. The resulting film had a coefficient of static friction of 0.31 and a surface roughness Rz of 1.30 μm. The height difference of the streaks provided on the film surface was 0.68 μm, and the maximum height difference Ry was 1.42 μm. The maximum width of the stripe-like irregularities was 1.9 μm, and the number of stripe-like irregularities was 230 / mm width. Regarding evaluation of peelability after pressing, the two sets of copper-clad laminates were peeled off and were OK.

[Example 8]
About 0.1 wt% of calcium hydrogen phosphate having an average particle diameter of 1 μm is added to polyamic acid obtained from 100 mol% of pyromellitic dianhydride, 70 mol% of 4,4′-diaminodiphenyl ether, and 30 mol% of paraphenylenediamine. 1 was processed in the same manner as in Example 1 using a polishing tape using silicon carbide having a particle size of 16 μm as an abrasive on the polyimide film having a thickness of 25 μm. The resulting film had a coefficient of static friction of 0.35 and a surface roughness Rz of 1.23 μm. The height difference of streaks provided on the film surface was 0.55 μm and the maximum height difference Ry was 1.30 μm. The maximum width of the stripe-like irregularities was 1.6 μm, and the number of stripe-like irregularities was 213 / mm width. Regarding evaluation of peelability after pressing, the two sets of copper-clad laminates were peeled off and were OK.

[Comparative Example 1]
Various properties were measured without treating a 25 μm thick polyimide film obtained from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether and manufactured from polyamic acid with an abrasive tape. There were no streak-like irregularities, the coefficient of static friction was 2.20, and the surface roughness Rz was 0.13 μm. Regarding the evaluation of peelability after pressing, the two sets of copper clad laminates were in close contact and were not peeled even when shaken by hand, and were NG.

[Comparative Example 2]
A polyamic acid obtained from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether was mixed with about 0.1% by weight of calcium hydrogen phosphate having an average particle diameter of 1 μm, and a manufactured polyimide film having a thickness of 25 μm was obtained. Various properties were measured without treatment with the abrasive tape. There were no streak-like irregularities, the coefficient of static friction was 0.74, and the surface roughness Rz was 0.68 μm. Regarding the evaluation of peelability after pressing, the two sets of copper clad laminates were in close contact and were not peeled even when shaken by hand, and were NG.

  Compared with the conventional method of adding inorganic particles to the film, the manufacturing method of the slippery polyimide film of the present invention is surely formed with streak-like irregularities, and the film has insulating properties, heat resistance, electrical properties, and mechanical properties. In addition, it is preferably used as a base film for a flexible circuit board laminated with a metal foil such as a copper foil.

It is explanatory drawing which shows the method of forming a stripe-shaped unevenness | corrugation on the film surface. It is explanatory drawing which shows the other method of forming a stripe-shaped unevenness | corrugation on the film surface. It is explanatory drawing which shows the further another method of forming a stripe-shaped unevenness | corrugation on the film surface.

Explanation of symbols

1: Unwinding roll, 2: Winding roll, 3, 3 ': Polishing roll, 4: Pressing roll

Claims (3)

When the surface of the polyimide film is treated with a polishing roll wound with a polishing tape , the height difference is 0.05 to 4.00 μm by rubbing the film surface with a polishing roll rotating in a direction opposite to the traveling direction of the film. A method for producing a slippery polyimide film, characterized in that stripe-shaped irregularities having a width of 0.1 to 10 μm are formed on the film surface in a range of 0.1 to 1000 / mm . 2. The method for producing a slippery polyimide film according to claim 1, wherein the abrasive constituting the surface of the polishing tape is any one of silicon carbide, aluminum oxide, chromium oxide, cerium oxide, and diamond particles. . The method for producing a slippery polyimide film according to claim 2, wherein the abrasive has a particle size of 0.1 to 100 μm.

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