JP2005119184A - Method for producing flexible metal foil polyimide substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a flexible metal foil polyimide substrate in which metal foil is laid on both sides of a polyimide film having a glass transition temperature of at least 300°C to overlap each other and heated/pressed continuously at the glass transition temperature of the polyimide film or above. <P>SOLUTION: The flexible metal foil polyimide substrate which is excellent in high temperature characteristics including solder heat resistance and high temperature peeling and high in heat resistance can be obtained cheaply. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a flexible metal foil polyimide substrate useful as an electronic material, and particularly to a method for producing a flexible metal foil polyimide substrate having excellent high temperature characteristics such as solder heat resistance and high temperature peeling.

  Conventionally, as a method for producing a flexible metal foil polyimide substrate, a method in which a thermoplastic polyimide is formed on a conductor and then a polyimide film is laminated is disclosed in Japanese Patent Application Laid-Open No. 1-244841 (Patent Document 1). Japanese Laid-Open Patent Publication No. 2000-103010 (Patent Document 2), Japanese Patent Laid-Open No. 6-190967 (Patent Document 3), and the like.

  This method uses thermoplastic polyimide, which has a low glass transition point, as an adhesive in order to bond a copper foil with an ordinary commercially available polyimide film (generally having a glass transition point of 300 ° C. or higher). doing. The thermoplastic polyimide having a low glass transition point mentioned here is a polyimide resin having a glass transition point of 350 ° C. or lower as disclosed in JP-A-1-2444841.

  In this method, since thermoplastic polyimide is used as an adhesive for thermocompression bonding, the use of thermoplastic polyimide is indispensable, but the heat resistance of the flexible metal foil polyimide substrate after bonding is the heat resistance of the thermoplastic polyimide used. Since it depends on the nature, use at high temperatures is limited.

JP-A-1-2444841 JP 2000-103010 A JP-A-6-190967

  This invention is made | formed in view of the said situation, and it aims at providing the manufacturing method of the flexible metal foil polyimide substrate which was excellent in heat resistance, and was excellent in high temperature characteristics, such as solder heat resistance and high temperature peeling.

  As a result of intensive studies to achieve the above object, the present inventors have overlapped a metal foil on both sides of a polyimide film having a glass transition point of 300 ° C. or higher, and this is at a temperature higher than the glass transition point of the polyimide film. By thermocompression bonding, it was found that a flexible metal foil polyimide substrate having high heat resistance was obtained at a very low cost, and the present invention was made.

  Accordingly, the present invention provides a flexible metal foil in which a metal foil is superimposed on both sides of a polyimide film having a glass transition point of 300 ° C. or higher, and is continuously heat-pressed at a temperature equal to or higher than the glass transition point of the polyimide film. A method for producing a polyimide substrate is provided.

  According to the production method of the present invention, a highly heat-resistant flexible metal foil polyimide substrate having excellent high-temperature characteristics such as solder heat resistance and high-temperature peeling can be obtained at a very low cost.

  The polyimide film of the present invention has a glass transition point of 300 ° C. or higher, preferably 350 ° C. or higher. When the glass transition point is less than 300 ° C., sufficient heat resistance cannot be obtained, and the molded product tends to be deformed or peeled off when using solder or the like. In addition, as an upper limit temperature of a glass transition point, it is preferable that it is 600 degrees C or less, especially 560 degrees C or less. If it exceeds 600 ° C., the physical strength of the polyimide film itself may be reduced by heating.

  The polyimide film used in the present invention may be prepared by imidizing a polyamic acid synthesized from a suitable acid anhydride and diamine.

Here, as an acid anhydride used at the time of manufacture of the polyimide film of this invention, a tetracarboxylic acid anhydride, its derivative (s), etc. are mentioned. In addition, although illustrated as tetracarboxylic acid below, these esterified products, acid anhydrides, and acid chlorides can of course be used. That is, as carboxylic acid, pyromellitic acid, 3,3 ', 4,4'-biphenyltetracarboxylic acid, 3,3', 4,4'-benzophenone tetracarboxylic acid, 3,3 ', 4,4' -Diphenylsulfone tetracarboxylic acid, 3,3 ', 4,4'-diphenyl ether tetracarboxylic acid, 2,3,3', 4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 3,3 ′, 4,4′-diphenylmethanetetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis ( 3,4-dicarboxyphenyl) hexafluoropropane, 3,4,9,10-tetracarboxyperylene, 2,2-bis [4- (3,4-dicarboxyphenoxy) Eniru] propane, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] hexafluoropropane, butane tetracarboxylic acid, and cyclopentane tetracarboxylic acid. Also included are trimellitic acid and its derivatives.
Furthermore, it can be modified with a compound having a reactive functional group to introduce a crosslinked structure or a ladder structure.

  On the other hand, the diamine used in the production of the polyimide film of the present invention includes p-phenylenediamine, m-phenylenediamine, 2'-methoxy-4,4'-diaminobenzanilide, 4,4'-diaminodiphenyl ether, diaminotoluene. 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 2,2-bis [4- (4- Aminophenoxy) phenyl] propane, 1,2-bis (anilino) ethane, diaminodiphenyl sulfone, diaminobenzanilide, diaminobenzoate, diaminodiphenyl sulfide, 2,2-bis (p-aminophenyl) propane, 2,2- Bis (p-aminophenyl) hexafluoropropaprop 1,5-diaminonaphthalene, diaminotoluene, diaminobenzotrifluoride, 1,4-bis (p-aminophenoxy) benzene, 4,4 '-(p-aminophenoxy) biphenyl, diaminoanthraquinone, 4,4'- Bis (3-aminophenoxyphenyl) diphenylsulfone, 1,3-bis (anilino) hexafluoropropane, 1,4-bis (anilino) octafluoropropane, 1,5-bis (anilino) decafluoropropane, 1,7 -Bis (anilino) tetradecafluoropropane, 2,2-bis [4- (p-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (2-aminophenoxy) phenyl] hex Fluoropropane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphenyl] hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) -3,5-ditrifluoro Methylphenyl] hexafluoropropane, p-bis (4-amino-2-trifluoromethylphenoxy) benzene, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-amino-3-trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) diphenylsulfone, 4,4'-bis (4-amino-5-trifluoro) Methylphenoxy) diphenylsulfone, 2,2-bis [4- (4-amino-3-trifluoromethylphenoxy) fe Nyl] hexafluoropropane, benzidine, 3,3 ', 5,5'-tetramethylbenzidine, octafluorobenzidine, 3,3'-methoxybenzidine, o-tolidine, m-tolidine, 2,2', 5,5 Diamines such as ′, 6,6′-hexafluorotolidine, 4,4 ″ -diaminoterphenyl, 4,4 ″ ′-diaminoquaterphenyl, and diisocyanates obtained by reaction of these diamines with phosgene, etc. Furthermore, diaminosiloxanes and the like can be mentioned.

The production of the polyimide film may be an existing production method and is not particularly limited. Moreover, it is also possible to use the poimide film generally marketed as shown below.
Product name: Apical Toray DuPont, product name: Kapton Ube Industries, product name: Upilex

  The polyimide film used in the present invention preferably has a thickness of 50 μm or less. When the thickness is larger than 50 μm, it is not easy to bend the substrate due to the thickness of the polyimide film itself, and so-called flexibility is lacking. Further, although depending on the hardness of the polyimide film to be used, a generally preferable thickness is 35 μm or less from the viewpoint of flexibility. In addition, as a minimum of the thickness of a polyimide film, it is preferable that it is 5 micrometers or more, especially 8 micrometers or more.

  In addition, examples of the metal foil used in the present invention include copper, iron, molybdenum, zinc, tungsten, nickel, chromium, aluminum, silver, or alloys thereof such as stainless steel. Preferred electronic material is copper.

  In addition, the metal foil as a conductor may be subjected to metal plating, surface oxidation, physical unevenness, or the like as a surface treatment, and may be further treated with a coupling agent such as silane or mercapto. Moreover, as thickness of metal foil, it is preferable that it is 5-50 micrometers, More preferably, it is 5-25 micrometers.

  In the present invention, it is indispensable to heat and pressure-bond the metal foil on both sides of the polyimide film. However, the heat-pressure bonding method may be a known general method, for example, JP-A-8-244168. As shown in Japanese Patent Laid-Open No. 9-116254, a roll laminating method for sandwiching and laminating between two metal rolls used in Japanese Patent Laid-Open No. 2003-118060, Japanese Patent Laid-Open No. 5-31869, etc. A so-called double belt press method can be used.

Moreover, the heating temperature in this case should just be the temperature more than the glass transition point of the polyimide film used, Preferably it is 350 degreeC or more, More preferably, it is 400 degreeC or more. The pressure at the time of pressure bonding varies depending on the flow property of the polyimide film to be used, but in a roll laminating machine or the like, the linear pressure is preferably 50 kg / cm or more, more preferably 75 kg / cm or more, and in a belt press machine or the like. The surface pressure is preferably 30 kg / cm ² or more, more preferably 50 kg / cm ² or more.

  Moreover, in this invention, it is preferable to use a cemented carbide for the part which contacts the metal foil of the apparatus to heat-press. The cause of this is unknown, and it is possible to bond even general stainless steel or carbon steel with chrome plating, etc. This phenomenon is reduced when a hard alloy is used. In addition, as the cemented carbide mentioned here, a mixture with commonly used tungsten carbide as a main component such as cobalt, nickel and the like can be mentioned, but diamond, aluminum oxide, chromium carbide, carbide A component having a high hardness such as silicon or boron carbide (having a Vickers hardness of 1,000 or more) may be used.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Example 1]
A 25 μm-thick polyimide film (Toray DuPont, product name: Kapton EN) is sandwiched between 18 μm-thick copper foil (Japan Energy, rolled copper foil) and a double belt press (made by Nishimura Machinery Co., Ltd.). The film was heated and pressure-bonded at 400 ° C. and 100 kg / cm ² , and the bonded product was wound into a roll. Note that a tungsten carbide alloy was used for the contact portion of the double belt press.
In order to evaluate the obtained one, a solder heat resistance test, a high temperature peeling test, and a surface observation were performed. Moreover, the glass transition point of the polyimide film was measured. The results are shown in Table 1.

[Example 2]
Example 1 was the same as Example 1 except that the temperature of thermocompression bonding was 360 ° C. and the pressure was 40 kg / cm ² .

[Example 3]
Example 1 was repeated except that the thickness of the polyimide film was 50 μm.

[Example 4]
220 g of pyromellitic acid (PMDA) was dissolved in 10 kg of dimethylacetamide (DMAc), cooled to 10 ° C., 110 g of p-phenylenediamine (PPD) was gradually added and reacted to obtain a polyimide precursor resin solution. The obtained solution was cast and the solvent was removed, followed by heating to 350 ° C. to obtain a polyimide film. The polyimide film had a thickness of 30 μm.
Both sides of the obtained polyimide film are sandwiched between 9 μm thick copper foil (manufactured by Japan Energy Co., Ltd., electrolytic copper foil). The roll was wound up into a roll. In addition, the contact part of the roll laminating machine used the chromium carbide type alloy.
In order to evaluate the obtained one, a solder heat resistance test, a high temperature peeling test, and a surface observation were performed. Moreover, the glass transition point of the polyimide film was measured. The results are shown in Table 1.

[Example 5]
Example 4 was the same as Example 4 except that the thermocompression bonding temperature was 650 ° C. and the pressure was 50 kg / cm.

[Example 6]
The polyimide film used was manufactured by Toray DuPont, trade name: Kapton H type (thickness 25 μm), and the same as Example 4 except that the heating compression temperature was 500 ° C.

[Example 7]
Example 6 was the same as Example 6 except that the pressure for thermocompression bonding was 200 kg / cm.

[Example 8]
Example 6 was the same as Example 6 except that the contact part of the roll laminator was chrome plated.

[Comparative Example 1]
Example 1 was repeated except that a polyimide film having a thermoplastic polyimide layer on both sides (manufactured by Kaneka Chemical Co., Ltd., trade name: Pixio, thickness 25 μm) was used.

[Comparative Example 2]
The same procedure as in Example 4 was conducted except that a polyimide film having a thermoplastic polyimide layer on both sides (Ube Industries, trade name: Upilex VT, thickness 25 μm) was used.

《Solder heat resistance test》
A laminate test piece (length 25 mm × width 25 mm) was immersed in a solder bath at 350 ° C. for 30 seconds, observed for peeling and swelling, and evaluated according to the following criteria.
Good: No peeling or swelling.
Bad: Peeled or swollen.

《High temperature peel test》
In accordance with JIS C 6471, a circuit having a width of 1 mm was prepared, and the peel strength was measured in a constant temperature oven at 200 ° C. with a pulling speed of 50 mm / min and a peeling angle of 90 °.

<< Surface observation >>
The surface of the laminate was visually observed and evaluated according to the following criteria.
Good: No peeling of copper foil.
Defect: There is peeling of copper foil.

《Glass transition point》
The glass transition point of the polyimide film was measured using a thermal analyzer (manufactured by Rheometric Science Co., Ltd., analyzer name: RSA-III).

Claims (5)

  A method for producing a flexible metal foil polyimide substrate, comprising: laminating a metal foil on both sides of a polyimide film having a glass transition point of 300 ° C. or higher and continuously heat-pressing the polyimide film at a temperature equal to or higher than the glass transition point of the polyimide film.   The method for producing a flexible metal foil polyimide substrate according to claim 1, wherein the polyimide film has a glass transition point of 350 ° C. or higher.   The method for producing a flexible metal foil polyimide substrate according to claim 1, wherein the polyimide film has a thickness of 50 μm or less.   The method for producing a flexible metal foil polyimide substrate according to claim 1, 2 or 3, wherein a cemented carbide is used in a portion that contacts the metal foil of the apparatus to be thermocompression bonded. The method for producing a flexible metal foil polyimide substrate according to any one of claims 1 to 4, wherein the metal foil is a copper foil.