JPH068036B2 - Method for producing metal / polyimide composite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyimide which is a low dielectric constant and high heat resistant insulating film,
The present invention relates to a method of manufacturing a composite including a conductor having low resistance such as copper, for example, a wiring board having a very small delay time.

Further, the present invention relates to a method for producing a metal / polyimide composite such as a flexible printed board or a conductive circuit which is indispensable for miniaturization of electronic parts.

[Conventional technology]

Conventionally, as a high-density wiring board, a multilayer wiring board of epoxy or glass cloth-containing maleimide resin and steel foil, or alumina /
Tungsten multilayer wiring boards have been used.

However, in the former case, the manufacturing method and the material are limited, and the wiring width cannot be miniaturized to 30 μm or less. In the latter case, the ceramic has a high dielectric constant and a very high temperature in the manufacturing process. Therefore, it is necessary to use a material such as tungsten having a large resistance value and a high melting point.

High-performance wiring boards are required as future high-speed, high-density wiring boards to replace these. The first candidate is a copper / polyimide wiring board. This is a high-performance wiring board that is manufactured by manufacturing a low-dielectric constant polyimide and low-resistance copper on a silicon substrate or a ceramic substrate by microfabrication similar to the semiconductor wiring manufacturing process. Is expected. As a prior art of this type, JP-A-57-181857 discloses a copper-polyimide multilayer wiring board.

However, when polyamic acid, which is a polyimide precursor, is heat-cured by contacting with copper or silver, there is a problem that a heat decomposition reaction that is very unthinkable due to the heat resistance of the original polyimide occurs at a temperature rise temperature of 300 ° C. or higher. is there. For example, when polyamic acid varnish is applied on a copper film and heat-cured, a clear discoloration is observed at 300 ° C. or higher, and the film becomes brittle and becomes mechanically very brittle. A similar phenomenon is observed in the manufacturing process of flexible printed boards and the curing process of conductive silver paste. Copper and silver have this problem as metals, and aluminum, titanium, nickel, and chromium are almost harmless.

Heretofore, when forming an imidized film by contacting with a metal as described above, an inert metal such as chromium or SiO ₂ or S is used.
There is a method of applying a polyamic acid precursor varnish on an inert film such as i ₃ N ₄ and then heat curing it, or a method of heat curing in a reducing atmosphere such as hydrogen when directly contacting the metal. . However, these methods have serious problems in that the number of steps is significantly increased and the running cost is high.

Even if these metal films are formed on the polyimide film and heated, the polyimide film is hardly adversely affected. Therefore, as a result of applying an imidized varnish on the metal film and curing it by heating, it was found that the polyimide did not deteriorate.

However, in this method, since the solubility of polyimide is very poor, it is necessary to use a cresol type that is harmful to the human body as a solvent, or use only a special one that is extremely soluble in polyimide itself. There is a problem such as not.

[Problems to be Solved by the Invention]

The above-mentioned prior art has a problem that the polyimide film is thermally deteriorated when polyamic acid is applied on the metal film and cured by heat.

Further, in order to prevent this thermal deterioration, it is necessary to thermally cure the polyimide film in a special atmosphere such as a reducing atmosphere.

Therefore, the present invention prevents the thermal deterioration of the polyimide film, which is a problem when the conventional polyamic acid is applied onto the metal film and thermally cured, and does not have the problem of deterioration even in a special atmosphere such as a reducing atmosphere. It is to provide a method for producing a reliable metal / polyimide composite.

[Means for Solving the Problems]

The present inventors have studied in detail the chemical reaction between a polyimide precursor and a metal that occurs when a metal / polyimide composite is obtained, which includes a step of bringing a polyimide precursor into contact with a metal to perform thermal imidization.

As a result, it was revealed that the metal was dissolved by the presence of carboxylic acid in polyamic acid, and when it was subsequently exposed to high temperature, the imide ring was thermally decomposed by the metal, and at the same time fine particulate metal oxide was deposited. I chose A phenomenon similar to this was also observed in the polyimide precursor having a sulfonic acid group, and it was found that the presence of the acidic functional group dissolves the metal. As a result of studying a solution for preventing the reaction between the polyimide precursor and the metal, it was found that there is no problem when polyamic acid in which carboxylic acid is masked with an ester group such as alkyl ester is used. The polyamic acid obtained by esterifying the carboxylic acid is obtained by reacting an acid anhydride with an alcohol, then converting the acid chloride with thionyl chloride, and further reacting with a diamine, or a half ester of tetracarboxylic acid and a diamine such as carbodiimide. It can be obtained by a method such as polycondensation with a dehydrating agent.

The present invention is characterized in that polyamic acid, which is a polyimide precursor, does not have an acidic functional group such as a carboxyl group or a sulfone group.

The polyimide precursor has the general formula This object can be achieved by the polyamic acid ester represented by

The present invention provides a method for producing a metal / polyimide composite, which comprises a step of applying a polyimide precursor on a conductive solid metal and a step of thermosetting the polyimide precursor to form a polyimide film,
The polyimide precursor has the general formula (In the formula (1), R ₁ and R ₂ are organic groups having 1 or more carbon atoms and may be the same or different from each other.
r ₁ is an aromatic group having two substituents, and Ar ₂ is an aromatic group having four substituents. The present invention provides a method for producing a metal / polyimide composite, characterized by being a polyamic acid ester represented by

Furthermore, the present invention comprises a step of forming a wiring made of a copper film on an electrically insulating substrate, a step of applying a polyimide precursor on the copper film, and a polyimide film formed by thermally curing the polyimide precursor. In the method for manufacturing a wiring board having the step of: (In the formula (1), R ₁ , R ₂ , Ar ₁ and Ar ₂ are the same as above.) A method for producing a wiring board is provided, which is a polyamic acid ester.

The present invention also includes a step of preparing a mixture in which the polyimide precursor and the fine metal powder are homogeneously mixed, a step of dissolving the mixture in an organic solvent, and a step of heating the organic solvent and then heating the polyimide precursor. A step of forming a polyimide film by curing, and a method for producing a metal / polyimide mixed composition comprising: (In the formula (1), R ₁ , R ₂ , Ar ₁ and Ar ₂ are the same as above.) A method for producing a metal / polyimide mixed composition, which is a polyamic acid ester. To do.

The present invention also provides a first step of forming a wiring made of a copper film on an electrically insulating substrate, a second step of applying a varnish in which a polyimide precursor is dissolved on the copper film, and the varnish. A multilayer wiring board comprising: a third step of thermosetting to form a polyimide film; a fourth step of forming a through hole in the thermosetting polyimide film; and a fifth step of forming copper wiring on the through hole. Wherein the polyimide precursor has the general formula (In the formula (1), R ₁ , R ₂ , Ar ₁ and Ar ₂ are the same as above.) A polyamic acid ester represented by the above formula is provided. is there.

The present invention also includes a first step of forming a wiring made of a copper film on a substrate having electrical insulation, a second step of applying a varnish in which a polyimide precursor is dissolved on the copper film, A third step of thermosetting the varnish to form a polyimide film; a fourth step of forming a through hole in the thermoset polyimide film; a fifth step of forming a copper wiring on the through hole; A step of forming a multilayer wiring having a desired number of layers by repeating the steps from the second step to the fifth step, and a method for producing a multilayer wiring board having: General formula (In the formula (1), R ₁ , R ₂ , Ar ₁ and Ar ₂ are the same as above.) A polyamic acid ester represented by the above formula is provided. Is.

The carbon number of R ₁ and R ₂ described above is preferably 1 or more and 20 or less.

Further, the metal / polyimide wiring board which is one of the present inventions,
It is manufactured by the following steps. A metal thin film is formed on a substrate (silicon wafer or ceramic substrate) by vapor deposition, sputtering or plating, and a pattern is formed by photolithography. A polyimide precursor varnish is applied and cured thereon, and a through hole pattern is formed by photolithography. Here, as the etching method for polyimide, a wet etching method using hydrazine or the like, and a dry etching method using oxygen gas ions or the like are used. Further, a metal thin film is formed again on this, and a pattern is formed by photolithography to form a second wiring layer. A polyimide layer is formed on this to form a through hole pattern. By repeating this, a multilayer wiring board can be obtained. Of course, it is also used in a form in which one layer of wiring is insulated with a polyimide film without being multilayered.

Furthermore, the composition in which the metal powder is dispersed in the polyimide precursor is useful as a conductive paste. However, when ordinary polyimide is used and silver or copper is used as a metal, there is a problem that the polyimide is decomposed by high temperature heat treatment. The present invention is also useful for this application. This is obtained by mixing the solution of the polyimide precursor of the present invention with copper, silver or an alloy powder thereof, and shows extremely high conductivity after heat curing. As the metal powder, spherical, scaly, or branched ones can be used, and the particle size is 0.1 to 10 μm so that there is no problem of mixing and sedimentation during curing during storage. From the viewpoint of the electric conductivity of the above, it is desirable that it is 65 to 85% by weight after curing.

The polyamitic acid suterel varnish of the present invention is obtained by heating polyamitic acid obtained by homopolymerization of an aminodicarboxylic acid derivative or by reacting an aromatic diamine and a tetracarboxylic acid derivative in a solvent or by reacting with a dehydrating agent. You can

Examples of tetracarboxylic acid derivatives include esters, acid anhydrides and acid chlorides.

When an acid anhydride is used, the reaction with a diamine is easy and it is preferable in terms of synthesis.

The synthesis reaction of polyamic acid is generally performed by N-methylpyrrolidone (NMP), dimethylformamide (DM).
F), dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), dimethyl sulfate, sulfolane, butyl lactone, cresol, phenol, halogenated phenol, cyclohexanone, dioxane, tetrahydrofuran, acetophenone, etc., in a solution of -20 to +20.
It is carried out in the range of 0 ° C.

Specific examples of the aminodicarboxylic acid derivative used in the present invention include 4-aminophthalic acid and 4-amino-5.
-Methylphthalic acid, 4- (p-aniline) -phthalic acid,
4- (3,5-dimethyl-4-anilino) phthalic acid and the like, esters thereof, acid anhydrides, acid chlorides and the like can be mentioned.

Examples of the aromatic diamine used in the present invention include p-phenylenediamine (p-PDA), 2,5-diaminotoluene, 2,5-diaminoxylene, diaminodeurene (2,3,5,6-tetramethylphenylene). Diamine), 2,5-diaminobenzotrifluoride, 2,5
-Diaminoanisole, 2,5-diaminoacetophenone, 2,5-diaminobenzophenone, 2,5-diaminodiphenyl, 2,5-diaminofluorobenzene, benzidine, o-tolidine (o-TLD), m − Tolidine,
3,3 ', 5,5'-tetramethylbenzidine, 3,
3'-dimethoxybenzidine, 3,3'-di (trifluoromethyl) benzidine, 3,3'-diacetylbenzidine, 3,3'-difluorobenzidine, octafluorobenzidine, 4,4 "-diamiterphenyl ( DATP),
Those having a linear conformation such as 4,4-diaminoquarterphenyl, m-phenylenediamine, 4,4'-diaminodiphenylmethane, 1,2-bis (aniline) ethane, 4,4'- Diaminodiphenyl ether (DDE), diaminophenyl sulfone, 2,
2-bis (p-aminophenyl) propane, 2,2-bis (p-aminophenyl) hexafluoropropane, 3,
3'-dimethyl-4,4-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, diaminotoluene, diaminobenzotrifluoride, 1,4-bis (p-aminophenoxy) Benzene, 4,4-bis (p-aminophenoxy) biphenyl, 2,2-bis {4- (p-aminophenoxy) phenyl} propane (DAPP), 2,2-bis {4- (m
-Aminophenoxy) phenyl} propane, 2,2-bis {4- (p-aminophenoxy) phenyl} hexafluoropropane (DAPFP), 2,2-bis {4- (m
-Aminophenyl) phenyl} hexafluoropropane,
2,2-bis {4- (p-aminophenoxy) -3,5
-Dimethylphenyl} hexafluoropropane, 2,2-
Bis {4- (p-aminophenoxy) -3,5-ditrifluoromethylphenyl} hexafluoropropane, p-bis (4-amino2-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) biphenyl sulfone, 4,4'-bis (3-
Amino-5-trifluoromethylphenoxy) biphenyl sulfone, 2,2-bis {4- (p-amino-3-trifluoromethylphenoxy (phenyl) hexafluoropropane, diaminoanthraquinone, 4,4- Bis (3-aminophenoxyphenyl) diphenyl sulfone, 1,3
-Bis (anilino) hexafluoropropane, 1,4-bis (anilino) octafluorobutane, 1,5-bis (anilino) decafluoropentane, 1,7-bis (anilino) tetradecafluoroheptane, general formula Or (R ₅ and R ₇ are divalent organic groups, R ₄ and R ₆ are monovalent organic groups, and p and q are integers greater than 1.).

The tetracarboxylic acid derivative used in the present invention includes pyromellitic acid (PMDA), methylpyromellitic acid, dimethylpyromellitic acid, di (trifluoromethyl) pyromellitic acid,
3,3 ', 4,4'-biphenyltetracarboxylic acid (s
-BPDA), 5,5'-dimethyl-3,3 ', 4,
4'-biphenyltetracarboxylic acid, p- (3,4-dicarboxyphenyl) benzene, 2,3,3 ', 4-tetracarboxydiphenyl, 3,3', 4,4'-tetracarboxydiphenyl Phenyl ether, 2,3,3 ', 4'
-Tetracarboxydiphenyl ether, 3,3 ',
4,4'-Tetracarboxybenzophenone (BTD
A), 2,3,3 ', 4'-tetracarboxybenzophenone, 2,3,6,7-tetracarboxynaphthalene, 1,4,5,7-tetracarboxynaphthalene,
1,2,5,6-tetracarboxynaphthalene, 3,
3'4,4'-tetracarboxydiphenylmethane,
2,3,3 ', 4'-tetracarboxyphenyl methane, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-carboxyphenyl)
Hexafluoropropane, 3,3 ', 4,4'-tetracarboxyphenyl sulfone, 3,4,9,10-tetracarboxyperylene, 2,2-bis {4- (3,4-dicarboxyphenoxy) ) Phenyl} propane, 2,2-
Bis {4- (3,4-dicarboxyphenoxy) phenyl} hexafluoropropane, butanetetracarboxylic acid,
Examples thereof include cyclopentanetetracarboxylic acid, and acid anhydrides, acid chlorides and esters thereof can also be used.

In addition, a typical alkyl ester among the esters of polyamic acid of the present invention is obtained by reacting the above acid anhydride with an alcohol and then with a chlorinating reagent such as thionyl chloride to once form a polyamic acid chloride. After that, it was obtained by reacting with diamine. The alkyl ester can also be obtained by polycondensing an esterified tetracarboxylic acid and a diamine with a dehydrating agent.

The polyamic acid ester used in the present invention has very excellent solubility and low varnish viscosity,
It has advantages such as excellent stability.

The polyamic acid ester varnish used in the present invention is
The coating film can be formed by a commonly used spin coating method or the like.

When forming a polyimide film, the polyamic acid ester is first dried in the range of 50 to 250 ° C, and then 250 to 40 ° C.
It is preferable to heat to about 0 ° C. for thermal imidization.

In the present invention, when further improving the adhesion between the polyimide and various bases, roughening the surface of the substrate,
The surface treatment is preferably performed with a silane coupling agent, a titanate coupling agent, an aluminum alcoholate, an aluminum chelate, a zirconium chelate, an aluminum acetylacetonate or the like.

Further, these surface treatment agents may be added to the polyimide. Alternatively, a diamine having a siloxane skeleton or tetracarboxylic dianhydride may be copolymerized.

In the polyamic acid ester used in the present invention, when the polyimide skeleton has a linear conformation, the thermal expansion coefficient of the coating film becomes very small and the elastic modulus becomes large.
Furthermore, the polyamitic acid ester used in the present invention can also lower the coefficient of thermal expansion, increase the elastic modulus, and further increase the fluidity by mixing powders of inorganic, organic, or metal powders, fibers, polyester strands, and the like. You can control your sex.

[Action]

The present invention, when forming a polyimide film in contact with copper or silver, the metal is dissolved in the carboxylic acid in the precursor polyamitic acid, it was found that it becomes a catalyst of thermal decomposition under high temperature conditions during curing, A polyimide precursor in which a carboxylic acid is masked with an ester group so that the metal does not dissolve is used.

By masking with an ester group, dissolution of the metal can be almost prevented, and consequently deterioration of the polyimide can be suppressed.

〔Example〕

Example 1 s-BPDA was reacted with methanol in N-2-methylpyrrolidone (abbreviated as NMP) at a molar ratio of 1: 2 to obtain a half-esterified product. This was reacted with thionyl chloride according to a conventional method to give an acid chloride, and then triethylamine and DDE were added thereto, the mixture was reacted at room temperature for 2 hours and at 50 ° C. for 2 hours, and then poured into a large amount of water to obtain a desired polyamic acid. An alkyl ester was obtained.

After drying this polyamic acid alkyl ester,
This was dissolved in MP to obtain a 15% varnish, and this polyamic acid alkyl ester varnish was spin-coated on the surface of a silicon wafer on which a copper thin film was deposited to form a coating film having a thickness of 10 μm.

Thermal imidization conditions are 100 ° C. for 30 minutes, 100 to 350 ° C.
The temperature was raised to 1 hour, and the temperature was maintained for 30 minutes. The atmosphere is in the air. The polyimide film was peeled from the silicon wafer, and the content of copper in the film, the color, the thermal decomposition temperature, and the tensile strength were measured. As a result, this film contains only 0.05% of copper as measured by an atomic absorption method, and the color of the film is yellow-orange and almost the same as the film formed on the inert SiO ₂ film. I understand. The decomposition temperature of this film in air is 450
It was found that the polyimide film had a very high tensile strength of 105 MPa and an elongation at break of 35%.

Example 2 BTDA and ethanol were reacted in N-2-methylpyrrolidone (abbreviated as NMP) at a molar ratio of 1: 2 to obtain a half-esterified product. This was mixed with p-PDA, and 1.2 times mol of dicyrrhoxin carbodiimide was added to the amino group to cause polycondensation. The reaction solution was poured into a large amount of water to obtain the desired polyamic acid alkyl ester.

After drying this polyamic acid alkyl ester, NM
A 15% varnish was dissolved in P to give a polyamic acid alkyl ester varnish, which was pin-coated on the surface of a silicon wafer on which a copper thin film was vapor-deposited in the same manner as in Example 1 to form a coating film having a thickness of 10 μm. The conditions for imidization by heating are the same as in Example 1. This polyimide film was peeled from the silicon wafer by etching a copper foil, and the content of copper in the film, color, thermal decomposition temperature, and tensile strength were measured. As a result, this film contains only 0.03% of copper, and the color of the film is yellow-orange, which is almost the same as the film formed on the inert SiO ₂ film. The film has a decomposition temperature in air of 450 ° C., a tensile strength of 250 MPa and an elongation at break of 13%, which are extremely excellent heat resistance and mechanical properties.

Example 3 The polyamitic acid alkyl ester varnish of Example 2 was
The surface of a silicon wafer having a silver thin film deposited thereon was spin-coated to form a coating film having a thickness of 10 μm. The thermal imidization conditions were the same as in Example 1 in air. The polyimide film was peeled from the silicon wafer, and the content of silver in the film, color, thermal decomposition temperature, and tensile strength were measured. As a result, this film contains only 0.011% of silver as measured by an atomic absorption method, and the color of the film is yellow-orange, which is almost the same as the film formed on the inactive SiO ₂ film. The decomposition temperature of this film in air is 45.
At 5 ° C, tensile strength is 260 MPa, elongation at break is 19
%, It has excellent heat resistance and mechanical properties.

Comparative Example 1 DAPP and BTDA were reacted in cresol at room temperature to once give polyamic acid and then at 150 ° C. for 3 hours to give an imidized varnish.

This imidized varnish was spin-coated on the surface of a silicon wafer on which a copper thin film was vapor-deposited to form a coating film having a thickness of 10 μm. The heating and drying conditions are 150 ° C. for 30 minutes, 150 to 3
The temperature was raised to 50 ° C. in 1 hour and kept at this temperature for 30 minutes. The atmosphere is in the air. The polyimide film was peeled from the silicon wafer, and the content of copper in the film, color, thermal decomposition temperature, and tensile strength were measured. As a result, this film contained only 0.03% of copper measured by the atomic absorption method, and the color of the film was yellow-orange, which was almost the same as the film formed on the inactive SiO ₂ film. Decomposition temperature in air is 410 ℃, tension temperature is 120MP
a, elongation at break is 10%.

Further, after the film was immersed in an etching solution of copper for about 5 hours, the thermal decomposition temperature and the mechanical properties of the film were measured. As a result, it showed almost the same values as those not immersed in the etching solution, and it was very chemically stable. It was found to be stable.

However, when compared with Comparative Example 2 and the like which will be described later, the heat resistance and mechanical properties are considerably inferior. This is because if the polyimide is not deteriorated but its solubility in a solvent is improved, the molecular skeleton becomes inferior in terms of flexible heat resistance and mechanical properties.

Comparative Example 2 p− was formed on the surface of the silicon wafer on which the silicon oxide film was formed.
N- of polyamitic acid obtained from PDA and s-BPDA
A 15% solution of methyl-2-pyrrolidone (abbreviated as NMP) was spin-coated to form a coating film having a thickness of 10 μm. The thermal imide conditions are the same as in Example 1. This was peeled from the silicon wafer, and the color, thermal decomposition temperature, and tensile strength were measured. As a result, this film has a yellow-orange color, its decomposition temperature in air is 510 ° C, and its tensioning temperature is 350MP.
a, the elongation at break is 25%, which is very excellent in heat resistance and mechanical properties. The content of copper in this film was, of course, very low, and was 0.0003% or less.

In addition, after the film was immersed in an etching solution of copper for about 5 hours, the thermal decomposition temperature and the mechanical properties of the film were measured. As a result, almost the same values as those not immersed in the etching solution were obtained.
As well as chemically very stable.

Thus, it can be seen that if the material is imidized without touching copper or silver, it has very excellent physical properties.

Comparative Example 3 As in Example 1, a copper thin film was formed on a silicon wafer by vapor deposition and patterned by etching, and the same polyamic acid varnish as in Comparative Example 2 was applied thereon, followed by thermal imide under the same conditions as in Comparative Example 2. Turned into As a result, the polyimide film on the copper pattern turned blackish brown and was peeled off from the discolored portion of the copper pattern when it was peeled off from the silicon wafer. Similarly, after copper was vapor-deposited on a silicon wafer, polyamic acid varnish was applied to form a pattern without forming a pattern, and thermal imidization was performed. Then, the film was peeled by immersing it in a copper etching solution. The content of copper in this film was 0.3%, which was very high. The thermal decomposition start temperature of this polyimide film is 330.
℃ and inferior to the film formed on the inactive film at about 200 ℃, and the film strength and breakability are 150MPa, 3%
And was very low. This may be due to the dissolution of copper due to the presence of the carboxylic acid in the polyimide precursor polyamic acid and the oxidative degradation of the imide ring due to the copper in the film. Comparing Comparative Examples 1 and 2 clearly shows that when polyamic acid is thermally imidized in a state of being in contact with copper, the heat resistance is significantly lowered by copper.

Example 4 Instead of copper in Comparative Example 2, a silver film was formed on a silicon wafer by vapor deposition, and the same polyamic acid varnish as in Comparative Example 2 was applied to perform thermal imidization. The thermal decomposition start temperature of the peeled polyimide film is 400 ° C, which is still better than that when it is formed on the copper film, but it is inferior to 100 ° C in heat resistance and is stronger than the film formed on the inactive film. , Breaking elongation 220 respectively
It was a very low MPa, 6%. This may be due to the dissolution of silver due to the presence of the carboxylic acid of polyamic acid, which is a polyimide precursor, and the oxidative deterioration of the imide ring due to silver in the film. In the case of silver as well, the heat resistance of polyimide is considerably reduced as in the case of silver.

Comparative Example 5 The same polyamitic acid varnish as in Comparative Example 2 was applied on a silicon wafer on which a copper thin film was vapor-deposited in the same manner as in Comparative Example 2 to perform thermal imidization. However, the atmosphere for curing and heating was not in air but in nitrogen gas mixed with a small amount of hydrogen, that is, in a slightly reducing atmosphere.
As a result, there was no change in the polyimide film. The thermal decomposition initiation temperature of the polyimide film peeled by removing copper by etching is 500 ° C, which is much higher than that of thermal imidization in air, and is almost the same as when cured as an inert film. It was the same. Moreover, the film strength and elongation at break are 3 respectively.
It can be seen that it is 50 MPa, 21%, which is somewhat inferior to the polyimide film on the SiO ₂ film, but is hardly affected by copper.
It is considered that copper is dissolved by the presence of the carboxylic acid of polyamic acid, which is a polyimide precursor, but the copper in the film is inactivated by heat treatment in a reducing atmosphere.

INDUSTRIAL APPLICABILITY The present invention can be applied to the method for producing a multichip image module shown in FIGS. The copper thin film forming the pattern of the copper wiring 2 is obtained on the insulating substrate or the ceramic wiring substrate 1 by the vacuum deposition method. The patterning of the copper wiring can be obtained by well-known chemical etching or dry etching.

Next, a varnish having a polyimide precursor (polyamic acid ester described in the present invention) is applied on the copper wiring film 2 and then heated to heat-imidize the polyimide precursor to form a polyimide film.

Further, this polyimide film is etched by a method such as chemical etching with a chemical such as hydrazine or dry etching such as ion milling to form an insulating film 3 having one or more through holes.

Then, a copper thin film is similarly formed in the through hole portion by a method such as vapor deposition to obtain an electrical connection with the underlying copper wiring film. Next, this copper film is etched into a desired pattern to form an upper layer copper wiring. By repeating the above steps, a multilayer wiring having a desired number of layers can be obtained. Finally,
The LSI 4 can be connected to the multilayer wiring with the solder 5 to obtain an LSI mounting board applied to a computer or the like.

FIG. 2 shows a pin array type LSI package having external connection terminals 6 obtained by the same manufacturing process as in FIG.

〔The invention's effect〕

The present invention provides a method for producing a metal / polyimide composite having almost no oxidative deterioration against the oxidative deterioration of a polyimide film, which has been a problem when polyamic acid is applied and cured on copper or silver. be able to. Further, it is possible to provide a method which does not have a problem such as running cost as compared with the method of thermally curing polyamic acid in a reducing atmosphere as described above.

[Brief description of drawings]

FIG. 1 is a sectional view of a high-density wiring board which is a specific application example of the present invention. FIG. 2 is a sectional view of a package substrate for a multi-chip module, which is a specific application example of the present invention. 1 ... Ceramic substrate, 2 ... Cu wiring, 3 ... Polyimide insulating film, 4 ... Si chip, 5 ... Solder, 6 ... Power supply pin.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuji Watanabe 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitate Manufacturing Co., Ltd.Hitachi Research Laboratories (72) Inventor Yukio Ogoshi 4026 Kuji Town, Hitachi City, Ibaraki Hitachi Co., Ltd. Hitachi Research Laboratory (72) Inventor Toshio Miyamoto 4026 Kuji Town, Hitachi City, Ibaraki Hitachi Co., Ltd. Hitachi Research Laboratory (72) Inventor Mikio Aizawa 4284 Touhou, Fukaya City, Saitama Prefecture Inventor Kazumasa Igarashi Fukaya Saitama Prefecture Ichijinmi 431-2 (72) Inventor Shu Mochizuki 77-4 Tokiwacho, Fukaya City, Saitama Prefecture

Claims (10)

[Claims] 1. A method for producing a metal / polyimide composite, comprising: a step of applying a polyimide precursor on a conductive solid metal; and a step of thermosetting the polyimide precursor to form a polyimide film. Polyimide precursor is a general formula (In the formula (1), R ₁ and R ₂ are organic groups having 1 or more carbon atoms and may be the same or different from each other.
r ₁ is an aromatic group having two substituents, and Ar ₂ is an aromatic group having four substituents. ) A method for producing a metal / polyimide composite, which is a polyamic acid ester represented by _2. The method for producing a metal / polyimide composite according to claim 1, wherein the carbon number of R ₁ and R ₂ is 1 or more and 20 or less. 3. A step of producing a wiring made of a copper film on a substrate having electrical insulation, a step of applying a polyimide precursor on the copper film, and a polyimide film by thermosetting the polyimide precursor. In the method for manufacturing a wiring board, the method including the step of forming (In the formula (1), R ₁ and R ₂ are organic groups having 1 or more carbon atoms and may be the same or different from each other.
r ₁ is an aromatic group having two substituents, and Ar ₂ is an aromatic group having four substituents. ) A method for producing a wiring board, which is a polyamic acid ester represented by 4. The method for manufacturing a wiring board according to claim 3, wherein the carbon number of R ₁ and R ₂ is 1 or more and 20 or less. 5. A step of preparing a mixture in which a polyimide precursor and a fine metal powder are mixed homogeneously, a step of dissolving the mixture in an organic solvent, and a step of heating the organic solvent and then heating the polyimide precursor. A step of forming a polyimide film by curing, and a method of producing a metal / polyimide mixed composition comprising: (In the formula (1), R ₁ and R ₂ are organic groups having 1 or more carbon atoms and may be the same or different from each other.
r ₁ is an aromatic group having two substituents, and Ar ₂ is an aromatic group having four substituents. ) A method for producing a metal / polyimide mixed composition, which is a polyamic acid ester represented by 6. The method for producing a metal / polyimide mixed composition according to claim 5, wherein the carbon number of R ₁ and R ₂ is 1 or more and 20 or less. 7. A first step of producing wiring made of a copper film on a substrate having electrical insulation, a second step of applying a varnish in which a polyimide precursor is dissolved on the copper film, and the varnish. A multi-layer wiring including a third step of forming a polyimide film by thermosetting, a fourth step of forming a through hole in the heat cured polyimide film, and a fifth step of forming a copper wiring on the through hole. In the method for producing a substrate, the polyimide precursor is represented by the general formula (In the formula (1), R ₁ and R ₂ are organic groups having 1 or more carbon atoms and may be the same or different from each other.
r ₁ is an aromatic group having two substituents, and Ar ₂ is an aromatic group having four substituents. ) A method for manufacturing a multilayer wiring board, which is a polyamic acid ester represented by 8. A method for producing a multilayer wiring board according to claim 7, wherein the carbon number of R ₁ and R ₂ is 1 or more and 20 or less. 9. A first step of producing wiring made of a copper film on a substrate having electrical insulation, a second step of applying a varnish in which a polyimide precursor is dissolved on the copper film, and the varnish. A third step of thermosetting the polyimide to form a polyimide film, a fourth step of forming a through hole in the thermoset polyimide film, and a fifth step of forming a copper wiring on the through hole. A step of forming a multi-layer wiring having a desired number of layers by repeating the steps from the second step to the fifth step, wherein the polyimide precursor has a general formula: (In the formula (1), R ₁ and R ₂ are organic groups having 1 or more carbon atoms and may be the same or different from each other.
r ₁ is an aromatic group having two substituents, and Ar ₂ is an aromatic group having four substituents. ) A method for producing a multilayer wiring board, which is a polyamic acid ester represented by 10. A method for producing a multilayer wiring board according to claim 9, wherein R ₁ and R ₂ have 1 to 20 carbon atoms.