JPH04235034A - Polyimide multilayer film and preparation thereof - Google Patents

Abstract

PURPOSE:To provide a multilayer film composed of soluble polyimide having a low dielectric constant and excellent in transparency, preparation thereof, and a polyimide acid solution to be used for it. CONSTITUTION:A polyimide multilayer film has a structure wherein a polyimide film is formed to a polyimide film soluble in an org. solvent and prepared by applying a polyamide acid solution using an org. solvent not dissolving polyimide on a polyimide film soluble in an org. solvent and curing the coated layer. The polyamide acid solution is prepared by dissolving polyamide acid being a precursor of polyimide soluble in a specific org. solvent in an org. solvent not dissolving polyimide. This polyimide multilayer film is useful for the preparation of a low light loss waveguide or a multilayer printed wring board of a low dielectric constant.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a polyimide multilayer film made of soluble polyimide and a method for producing the same, particularly a polyimide multilayer film for use in electronic components, electronic/optical components, and optical components, and a method for producing the same. The present invention relates to a polyamic acid solution useful in.

0002

BACKGROUND OF THE INVENTION Polyimide has been widely used mainly in the aerospace and aerospace fields because of its excellent heat resistance. Recently, it has been used as an interlayer insulating film for electronic components and as a material for multilayer wiring boards, taking advantage of its excellent heat resistance, which allows it to withstand semiconductor process temperatures. These polyimides are required to have a low dielectric constant from the viewpoint of increasing signal speed. Polyimide is also beginning to be expected to be used as an optical waveguide in electronic/optical components and optical components, and polyimide is required to have low optical transmission loss, that is, transparency. Recently, various polyimides having such low dielectric constant and transparency have been developed. For example, Sampe Journal (S
AMPE JOURNAL) July/August issue (1985
), page 28 reports some examples of transparent polyimides. It is stated that one of the characteristics of these transparent polyimides is that they are soluble in solvents. Furthermore, the present inventors disclosed a transparent fluorinated polyimide with a low dielectric constant in Japanese Patent Application No. 1-201170. Many of these polyimides are soluble in solvents.

By the way, when these low dielectric constant, transparent polyimides are used as interlayer insulating films or optical waveguides, it is often required to have a multilayer structure. That is, it is necessary to form at least one more polyimide film on top of the polyimide film. However, since these low dielectric constant, transparent polyimides have the property of being soluble in solvents, it is difficult to form them into multilayers, and multilayers of these have not yet been realized.

0004

[Problems to be Solved by the Invention] Conventionally, it has been impossible to form multiple layers of soluble polyimide. The object of the present invention is to provide a soluble polyimide multilayer film with a low dielectric constant and excellent transparency, a method for producing the same, and a polyamic acid solution useful therein.

[0005]

[Means for Solving the Problems] To summarize the present invention, the first invention of the present invention relates to a polyimide multilayer film, in which a polyimide film is formed on an upper layer of a polyimide film soluble in an organic solvent. It is characterized by the presence of Second aspect of the present invention
The invention relates to a method for producing a polyimide multilayer film, and is characterized in that a polyamic acid solution dissolved in an organic solvent that does not dissolve the polyimide is applied to the upper layer of a polyimide film that is soluble in an organic solvent, and then cured. . A third invention of the present invention relates to a polyamic acid solution, which is characterized in that a polyamic acid, which is a precursor of polyimide that is soluble in a specific organic solvent, is dissolved in an organic solvent that does not dissolve the polyimide. do.

In order to achieve the above object, the present inventors investigated the solubility of soluble polyimide and its precursor, polyamic acid, in various solvents and found that there is a difference in solubility between polyimide and polyamic acid. They discovered that there is a solvent that does not dissolve polyimide but dissolves its precursor, polyamic acid.
The present invention has now been completed.

[0007] As the soluble polyimide used in the present invention, all soluble polyimides can be used. For example, among the polyimides, polyimide copolymers, and polyimide mixtures produced from tetracarboxylic acids or derivatives thereof and diamines shown below, those soluble in solvents may be mentioned.

Examples of tetracarboxylic acids and their derivatives such as acid anhydrides, acid chlorides, and esters include the following. Here, an example of a tetracarboxylic acid will be given.

(trifluoromethyl)pyromellitic acid,
Di(trifluoromethyl)pyromellitic acid, di(heptafluoropropyl)pyromellitic acid, pentafluoroethylpyromellitic acid, bis{3,5-di(trifluoromethyl)phenoxy}pyromellitic acid, 2,3,3 ′、
4'-biphenyltetracarboxylic acid, 3,3',4,4
'-Tetracarboxydiphenyl ether, 2,3',
3,4'-tetracarboxydiphenyl ether, 3,
3',4,4'-benzophenonetetracarboxylic acid, 2
, 3,6,7-tetracarboxynaphthalene, 1,4,
5,7-tetracarboxynaphthalene, 1,4,5,6
-Tetracarboxynaphthalene, 3,3',4,4'-
Tetracarboxydiphenylmethane, 3,3',4,4
'-Tetracarboxydiphenyl sulfone, 2,2-bis(3,4-dicarboxyphenyl)propane, 2,2
-bis(3,4-dicarboxyphenyl)hexafluoropropane, 5,5'-bis(trifluoromethyl)-
3,3',4,4'-tetracarboxybiphenyl, 2
,2',5,5'-tetrakis(trifluoromethyl)
-3,3',4,4'-tetracarboxybiphenyl,
5,5'-bis(trifluoromethyl)-3,3',4
, 4'-tetracarboxydiphenyl ether, 5,5
'-Bis(trifluoromethyl)-3,3',4,4'
-Tetracarboxybenzophenone, bis{(trifluoromethyl)dicarboxyphenoxy}benzene, bis{(trifluoromethyl)dicarboxyphenoxy}(
trifluoromethyl)benzene, bis(dicarboxyphenoxy)(trifluoromethyl)benzene, bis(dicarboxyphenoxy)bis(trifluoromethyl)benzene, bis(dicarboxyphenoxy)tetrakis(
trifluoromethyl)benzene, 3,4,9,10-tetracarboxyperylene, 2,2-bis{4-(3,4
-dicarboxyphenoxy)phenyl}propane, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, 2,2-bis{4-(3,4-dicarboxyphenoxy)phenyl}hexafluoropropane, bis{(trifluoromethyl) dicarboxyphenoxy}biphenyl, bis{(trifluoromethyl)dicarboxyphenoxy}bis(trifluoromethyl)biphenyl, bis{(
trifluoromethyl)dicarboxyphenoxy}diphenyl ether, bis(dicarboxyphenoxy)bis(
trifluoromethyl)biphenyl, etc.

[0010] Examples of diamines include the following. m-phenylenediamine, 2,4-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodurene, 4-(1H,1H,11H-eicosafluoroundecanoxy)-1,3-diaminobenzene, 4-
(1H,1H-perfluoro-1-butanoxy)-1,
3-diaminobenzene, 4-(1H,1H-perfluoro-1-heptanoxy)-1,3-diaminobenzene,
4-(1H,1H-perfluoro-1-octanoxy)
-1,3-diaminobenzene, 4-pentafluorophenoxy-1,3-diaminobenzene, 4-(2,3,5
, 6-tetrafluorophenoxy)-1,3-diaminobenzene, 4-(4-fluorophenoxy)-1,3-
Diaminobenzene, 4-(1H,1H,2H,2H-perfluoro-1-hexanoxy)-1,3-diaminobenzene, 4-(1H,1H,2H,2H-perfluoro-1-dodecanoxy)-1, 3-diaminobenzene, p
-phenylenediamine, (2,5-)diaminotoluene, 2,3,5,6-tetramethyl-p-phenylenediamine, (2,5-)diaminobenzotrifluoride,
Bis(trifluoromethyl)phenylenediamine, diaminotetra(trifluoromethyl)benzene, diamino(pentafluoroethyl)benzene, 2,5-diamino(perfluorohexyl)benzene, 2,5-diamino(perfluorobutyl)benzene, benzidine, 2,2
'-Dimethylbenzidine, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3',5,5'-tetramethylbenzidine, 3,3'-diacetylbenzidine ,2,2
'-Bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-
4,4'-diaminobiphenyl, octafluorobenzidine, 4,4'-diaminodiphenyl ether, 4,4
'-Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 2,2-bis(p-aminophenyl)propane, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4 ,4'-
Diaminodiphenylmethane, 1,2-bis(anilino)
Ethane, 2,2-bis(p-aminophenyl)hexafluoropropane, 1,3-bis(anilino)hexafluoropropane, 1,4-bis(anilino)octafluorobutane, 1,5-bis(anilino)deca Fluoropentane, 1,7-bis(anilino)tetradecafluoroheptane, 2,2'-bis(trifluoromethyl)-4,
4'-diaminodiphenyl ether, 3,3'-bis(
trifluoromethyl)-4,4'-diaminodiphenyl ether, 3,3',5,5'-tetrakis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 3,3'-bis(trifluoromethyl)- 4,4'-
Diaminobenzophenone, 4,4''-diamino-p-
Terphenyl, 1,4-bis(p-aminophenyl)benzene, p-bis(4-amino-2-trifluoromethylphenoxy)benzene, bis(aminophenoxy)bis(trifluoromethyl)benzene, bis(aminophenoxy) ) tetrakis(trifluoromethyl)benzene,
4,4'''-diamino-p-quarterphenyl, 4
, 4'-bis(p-aminophenoxy)biphenyl, 2
,2-bis{4-(p-aminophenoxy)phenyl}
Propane, 4,4'-bis(3-aminophenoxyphenyl)diphenylsulfone, 2,2-bis{4-(4-
aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-(3-aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-(2
-aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-(4-aminophenoxy)-3
,5-dimethylphenyl}hexafluoropropane, 2
,2-bis{4-(4-aminophenoxy)-3,5-
ditrifluoromethylphenyl}hexafluoropropane, 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(
3-amino-5-trifluoromethylphenoxy)diphenylsulfone, 2,2-bis{4-(4-amino-3
-trifluoromethylphenoxy)phenyl}hexafluoropropane, bis{(trifluoromethyl)aminophenoxy}biphenyl, bis[{(trifluoromethyl)aminophenoxy}phenyl]hexafluoropropane, diaminoanthraquinone, 1,5-diaminonaphthalene , 2,6-diaminonaphthalene, bis{2-[(
aminophenoxy)phenyl]hexafluoroisopropyl}benzene, etc.

The polyimide layer formed on the soluble polyimide layer is not particularly limited and any polyimide can be used.

As a method for manufacturing the polyimide multilayer film of the present invention, the following method can be used, for example. silicon, quartz,
A solution of soluble polyimide or its precursor, polyamic acid, dissolved in a solvent is applied onto a substrate made of polyimide or the like by a method such as spin coating, and cured under predetermined temperature conditions to obtain a soluble polyimide film. Next, a solvent that does not dissolve the soluble polyimide of the first layer is determined in advance through a test tube test, and the polyamic acid, which is the precursor of the polyimide that is to form the second layer, is dissolved in that solvent to obtain a polyamic acid solution. . This polyamic acid solution is applied onto the first layer made of soluble polyimide by a method such as spin coating, and then cured to obtain a second layer. If necessary, a third or higher multilayer film is formed in the same manner.

The present invention is characterized in that a polyamic acid dissolved in a solvent that does not dissolve the soluble polyimide is used as the upper layer of the soluble polyimide, and for other manufacturing methods, general polyimide multilayer film manufacturing methods can be used.

[0014] As a method for producing the polyamic acid solution of the present invention, for example, the following method can be used. For example, it is produced by polymerizing diamine and acid dianhydride, which are raw materials for the synthesis of polyimide that is soluble in organic solvents, in an organic solvent that does not dissolve the polyimide but dissolves its precursor polyamic acid. can do. If the degree of polymerization does not increase with the above organic solvent, synthesize high molecular weight polyamic acid using a normal amide solvent, isolate the polyamic acid using a reprecipitation method, etc., and then use the precursor instead of dissolving the polyimide. The desired polyamic acid solution can be obtained by dissolving the polyamic acid in an organic solvent that dissolves the polyamic acid.

[0015]

EXAMPLES The present invention will be explained in more detail using some examples below, but the present invention is not limited to these examples.

Example 1 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl as the diamine and 2,2' as the acid anhydride were deposited on a 3-inch diameter silicon wafer whose surface was a silicon oxide layer. -bis(3,4-dicarboxyphenyl)-
15 wt% N of polyamic acid, a precursor of soluble polyimide produced using hexafluoropropane dianhydride,
An N-dimethylacetamide (DMAc) solution was applied by spin coating so that the film thickness after heating was 10 μm, and then heat treatment was performed at a maximum temperature of 350°C. In this way, the first layer of soluble polyimide film was produced. Small pieces of this soluble polyimide and its precursor polyamic acid were placed in test tubes containing various solvents to test their solubility. The results are shown in Table 1.

[0017]

[Table 1] Table 1 (○ if soluble in solvent, × if insoluble)──────────────
──────────────────────
Solvent Example 1
Solubility of Example 1
Polyimide Polyamic acid───
──────────────────────────
──────── Methanol
×
○ Ethanol
×
○ n-butanol
×
○ n-pentanol
×
○ n-hexanol
×
○ n-heptanol
×
○ n-octanol
×
○ Diethylene glycol ○
○
diethyl ether methyl isobutyl ketone ×
○ Diethylene glycol ○
○ Dimethyl ether

Bis(2-butoxy
× ×
ethyl) ether

Acetophenone
○
○ Isooctyl acetate
×
× 1,2-diacetoxyethane
○
○ Cyclohexanol ×
×
acetone
○ ○
Tetrahydrofuran ○
○ Ethyl acetate ○
○
benzene
× ×
hexane
×
×────────────────────────
────────────

Alcohol solvent, methyl isobutyl ketone does not dissolve polyimide,
It was found to dissolve polyamic acid. Therefore, next, 15% n of polyamic acid, which is a precursor of this soluble polyimide, was added.
- Prepare a hexyl alcohol solution, and the film thickness after heating is 1
After coating by spin coating to a thickness of 0 μm, heat treatment was performed at a maximum temperature of 350°C. As a result, the film thickness was 20 μm.
We were able to form a bilayer film of soluble polyimide. As a result of observing the cross section of the two-layer film using a scanning electron microscope, it was confirmed that the interface between both layers was formed without being attacked by the solvent.

Example 2 The same procedure as in Example 1 was carried out except that n-hexyl alcohol was replaced with methyl isobutyl ketone as the solvent for the polyamic acid solution which was the precursor of the soluble polyimide of the second layer, and the film thickness was 20 μm. We were able to form a bilayer film of soluble polyimide.

Examples 3 to 10 In Example 1, 2,2′-bis(trifluoromethyl)-
Using a polyamic acid produced from 4,4'-diaminobiphenyl and the acid anhydride listed in Table 2, the same procedure as in Example 1 was carried out, and a two-layer film of soluble polyimide with a film thickness of 20 μm could be formed. Ta.

[0021]

[Table 2]
Table 2────────────────
────────────────────── Example 1st layer soluble polyimide precursor 2nd
Used for layer polyimide precursor
Acid anhydride used on the body Acid anhydride used──────────────────────
──────────────── Example 3
6FDA:PMDA=1:0 6FDA:PMD
A=9:1────────────────────
──────────────── Example 4
6FDA:PMDA=1:0 6FDA:PM
DA=8:2────────────────────
────────────────── Example 5
6FDA:PMDA=1:0 6FDA:P
MDA=7:3──────────────────
────────────────── Example 6
6FDA:PMDA=1:0 6FDA:
PMDA=6:4──────────────────
──────────────────── Example 7
6FDA:PMDA=9:1 6FDA
:PMDA=1:0────────────────
──────────────────── Example 8 6FDA:PMDA=9:1 6FD
A: PMDA=9:1────────────────
────────────────────── Example 9 6FDA:PMDA=9:1 6F
DA:PMDA=8:2──────────────
────────────────────── Example 10 6FDA:PMDA=8:2
6FDA:PMDA=7:3────────────
────────────────────────
*6FDA; 2,2-bis(3,4-dicarboxyphenyl)-hexaflu
Olopropane dianhydride *PMDA; Pyromellitic dianhydride

Example 11 8.88 g of 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride was placed in an Erlenmeyer flask.
g (20.0 mmol) and 6.4 g of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl
0 g and 100 g of DMAc were added. This mixture was stirred at room temperature under a nitrogen atmosphere for three days to obtain a DMAc solution of polyamic acid. This material was spin-coated on an aluminum plate and heated at 70°C for 2 hours in a nitrogen atmosphere.
1 hour at 160°C, 30 minutes at 250°C, then 350°C
It was heated and cured for 1 hour. 10% of this aluminum plate
A polyimide film was obtained by dissolving the aluminum plate by immersing it in an aqueous HCl solution. Also, DMAc of polyamic acid
The solution was dropped into water, and the precipitated white polymeric solid was filtered and dried to obtain a polyamic acid. Small pieces of this soluble polyimide and its precursor polyamic acid were placed in test tubes containing various solvents to test their solubility. The results are shown in Table 1. It was found that the alcoholic solvent methyl isobutyl ketone does not dissolve polyimide but dissolves polyamic acid. Next, polyamic acid, which is a precursor of this soluble polyimide, was dissolved in an n-hexyl alcohol solution to obtain a 15 wt % solution of the polyamic acid of the present invention.

[0023] After heating this polyamic acid solution on a soluble polyimide film formed on an aluminum plate, the film thickness was 10
After coating by spin coating to a thickness of μm, heat treatment was performed at a maximum temperature of 350°C. As a result, a two-layer film of soluble polyimide with a film thickness of 20 μm was formed. As a result of observing the cross section of the two-layer film using a scanning electron microscope, it was confirmed that the interface between both layers was formed without being attacked by the solvent.

Example 12 A polyamic acid solution was obtained in the same manner as in Example 11, except that n-hexyl alcohol was replaced with methyl isobutyl ketone as the solvent for the polyamic acid solution, which was a precursor of soluble polyimide. In the same manner, a two-layer film of soluble polyimide having a film thickness of 20 μm could be formed.

Examples 13 to 16 In Example 11, 2,2'-bis(trifluoromethyl)-
A polyamic acid solution was obtained in the same manner as in Example 11 using a polyamic acid produced from 4,4'-diaminobiphenyl and the acid anhydride listed in Table 3. In the same manner, a two-layer film of soluble polyimide having a film thickness of 20 μm could be formed.

Examples 17 to 20 In Example 12, 2,2'-bis(trifluoromethyl)-
A polyamic acid solution was obtained in the same manner as in Example 12 using a polyamic acid produced from 4,4'-diaminobiphenyl and the acid anhydride listed in Table 3. In the same manner, a two-layer film of soluble polyimide having a film thickness of 20 μm could be formed.

[0027]

[Table 3]
Table 3 ────
──────────────────────
Example Acid anhydride used in polyimide precursor ────
────────────────────────
Example 13 6F
DA:PMDA=9:0 ────
──────────────────────
Example 14 6FD
A:PMDA=8:2 ──────
──────────────────────
Example 15 6FDA
:PMDA=7:3 ──────
────────────────────
Example 16 6FDA:
PMDA=6:4 ────────
────────────────────
Example 17 6FDA:P
MDA=9:1 ────────
────────────────────
Example 18 6FDA:PM
DA=8:2 ──────────
──────────────────
Example 19 6FDA:PMD
A=7:3 ──────────
──────────────────
Example 20 6FDA:PMDA
=6:4 ────────────
────────────────

Example 2
1 A 15% n-hexyl alcohol solution of polyamic acid, which is a precursor of the soluble polyimide used in Example 1, was added to the upper layer of the two-layer film of soluble polyimide obtained in Example 1 so that the film thickness after heating was 10 μm. After coating by spin coating, heat treatment was performed at a maximum temperature of 350°C. As a result, a three-layer film of soluble polyimide with a film thickness of 30 μm was formed. As a result of observing the cross section of the three-layer film with a scanning electron microscope,
It was confirmed that the interface between each layer was formed without being attacked by the solvent.

Comparative Example 1 A 15% DMAc solution of polyamic acid, which is a precursor of soluble polyimide, was used in place of the 15% n-hexyl alcohol solution of polyamic acid, which is a precursor of soluble polyimide, in Example 1 or 11. An attempt was made to produce a multilayer film in the same manner as in Example 1 or 11. However, the first layer of soluble polyimide film was dissolved, and a multilayer film could not be produced.

[0030]

As explained above, according to the present invention, a polyimide multilayer film having a structure having a polyimide layer on a soluble polyimide layer can be provided. Using this multilayer film, it is possible to manufacture low optical loss buried polyimide optical waveguides, low dielectric constant polyimide multilayer wiring boards, etc.

Claims (7)

[Claims] 1. A polyimide multilayer film, characterized in that a polyimide film is formed on an organic solvent-soluble polyimide film. [Claim 2] At least one of the organic solvent-soluble polyimide films is 2,2'-bis(trifluoromethyl).
The polyimide multilayer film according to claim 1, which is a polyimide, a polyimide copolymer, or a polyimide mixture containing -4,4'-diaminobiphenyl as a synthetic raw material. 3. A method for producing a polyimide multilayer film, which comprises applying a polyamic acid solution dissolved in an organic solvent that does not dissolve the polyimide onto the upper layer of a polyimide film that is soluble in an organic solvent, and curing the polyimide solution. Claim 4: A polyimide film soluble in an organic solvent comprises 2
, 2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl as a synthetic raw material, the polyimide is a polyimide, a polyimide copolymer, or a polyimide mixture. Method for manufacturing multilayer films. 5. Polyamic acid and polyamic acid copolymer containing 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl as a synthetic raw material as the polyamic acid in the polyamic acid solution dissolved in an organic solvent. The method for producing a polyimide multilayer film according to claim 3 or 4, characterized in that a combination or a polyamic acid mixture is used. 6. A polyamic acid solution, which is obtained by dissolving a polyamic acid precursor of a polyimide that is soluble in a specific organic solvent in an organic solvent that does not dissolve the polyimide. 7. The polyimide is a polyimide, a polyimide copolymer, or a polyimide mixture containing 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl as a synthetic raw material. The polyamic acid solution according to claim 6.