JPH02167741A - Preparation of metal/polyimide composite - Google Patents

Abstract

PURPOSE:To prevent the heat deterioration of the polyimide film applied to a metal film at the time of heat-curing by constituting a polyimide precursor of specific polyamic ester. CONSTITUTION:A copper membrane to be formed into a pattern of copper wiring film 2 is formed on a substrate or ceramic wiring substrate having insulating properties and varnish of a polyimide precursor (polyamic ester) is applied to the copper wiring film 2 and heated to form a polyimide film. This polyimide film is etched to form an insulating film 3 having through-holes. Subsequently, a copper membrane is formed to the through-hole parts to obtain the electrical connection with the copper wiring film of a lower layer. Next, this copper membrane is etched into a desired pattern to form copper wiring of an upper layer. The above mentioned process is repeated. At this time, the polyimide precursor is polyamic ester represented by formula I (wherein R1 and R2 are a 1 or more C org. group and may be same or different each other, Ar1 is an aromatic group having two substituents and Ar2 is an aromatic group having four substituents). By this method, the deterioration of a polyimide film is suppressed to low running cost and a high speed high density wiring board is obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a composite material containing polyimide, which is a low dielectric constant and high heat resistant insulating film, and a conductor such as copper with low resistance, such as a material having a very small delay time. Relates to the manufacturing method of wiring boards.

Furthermore, the present invention relates to a method for manufacturing metal/polyimide composites such as flexible printed boards or conductive circuits, which are essential for miniaturizing electronic parts.

[Conventional technology]

Conventionally, multilayer wiring boards made of maleimide resin containing epoxy or glass cloth and copper foil, and alumina/tungsten multilayer wiring boards have been used as high-density wiring boards.

However, in the former case, there are restrictions on manufacturing methods and materials, making it impossible to miniaturize the wiring width to 30 μm or less, and in the latter case, the ceramic has a high dielectric constant and the manufacturing process requires extremely high temperatures. Therefore, it is necessary to use a material with a high resistance value and a high melting point, such as tungsten.

A high-performance wiring board is required as a future high-speed, high-density wiring board to replace these. The first candidate is a copper/polyimide wiring board. this is.

It is expected to be an extremely high-performance wiring board that is produced by using a microfabrication process similar to the manufacturing process of semiconductor wiring to fabricate low-permittivity polyimide and low-resistance copper on a silicon or ceramic substrate.

As a prior art of this type, Japanese Patent Application Laid-Open No. 181857/1983 describes a copper polyimide multilayer wiring board.

However, when polyamic acid, which is a polyimide precursor, is heated and cured by contacting with copper or silver.

When the temperature rises above 300℃, there is a problem that an unimaginable thermal decomposition reaction occurs due to the inherent heat resistance of polyimide.For example, when polyamic acid varnish is applied on a copper film and cured by heat, A clear discoloration is observed above, and the film becomes brittle and becomes mechanically very brittle. Similar phenomena are also observed in the manufacturing process of flexible printed boards and the curing process of conductive silver paste. This problem is particularly true for metals such as copper and silver, while aluminum, titanium, nickel, chromium, etc. are almost harmless.

Until now, when forming an imidized film by contacting metals, inert metals such as ROM, SiO2, 5
There are methods such as forming an inert film such as iaN4 and then applying a polyamic acid precursor varnish and curing it with heat, and when directly contacting the metal, heating and curing it in a reducing atmosphere such as hydrogen.

However, these methods require a significant increase in the number of steps.

This includes major problems in terms of running costs, etc.

Even if these metal films are formed on a polyimide film and heated, there is almost no adverse effect on the polyimide film.

Therefore, imidized varnish was applied on the gold GC film.

As a result of heating and curing, it was found that there was no deterioration of the polyimide.

However, since the solubility of polyimide is very poor, this method requires the use of cresol-based solvents that are harmful to the human body, and requires the use of special solvents that are extremely soluble for the polyimide itself. There are problems such as not having one.

[Problem to be solved by the invention]

The above-mentioned conventional technology has a problem in that when polyamic acid is applied onto a metal film and thermally cured, the polyimide film deteriorates due to heat.

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

Therefore, the present invention aims to prevent the thermal deterioration of the polyimide film, which would be a problem when it is thermally cured, by coating the conventional polyamic acid on the metal film. An object of the present invention is to provide a reliable method for manufacturing a metal/polyimide composite.

[Means to solve the problem]

The present inventors studied in detail the chemical reaction between a polyimide precursor and a metal that occurs when obtaining a metal/polyimide composite, which includes a step of thermally imidizing a polyimide precursor by bringing it into contact with a metal.

As a result, it was revealed that the metal dissolves due to the presence of carboxylic acid in polyamic acid, and then when exposed to high temperatures, the imide ring is thermally decomposed by the metal, and fine particles of metal oxide are precipitated at the same time. A similar phenomenon was observed in polyimide precursors with sulfonic acid groups, and it was determined that the presence of acidic functional groups causes the metal to dissolve.

As a result of investigating solutions to prevent the reaction between the polyimide precursor and metal, it was found that there would be no problem using polyamic acid in which carboxylic acid was masked with ester groups such as alkyl esters. A polyamic acid obtained by esterifying this carboxylic acid can be produced by reacting an acid anhydride with an alcohol, converting it into an acid chloride with thionyl chloride, and then reacting it with a diamine. It can be obtained by polycondensation using a dehydrating agent.

The present invention is characterized in that the polyamic acid, which is a polyimide precursor, does not contain acidic functional groups such as carboxyl groups and sulfone groups.

This objective can be achieved if the polyimide precursor is a polyamic acid ester represented by the general formula.

The present invention is a method for producing a metal/polyimide composite comprising the steps of applying a polyimide precursor onto a conductive solid metal and thermally curing the polyimide precursor to form a polyimide film, the method comprising:
The polyimide precursor has the general formula (formula (1), where R1 and R2 are organic groups having 1 or more carbon atoms, and may be the same or different from each other, and Arx is an aromatic group having two substituents. Family group.

Art is an aromatic group with four substituents. ) A method for producing a metal/polyimide composite is provided, which is a polyamic acid ester represented by:

Furthermore, the present invention includes a step of producing a wiring made of a copper film on an electrically insulating substrate, and a step of applying a polyimide precursor on the copper film.

a step of forming a polyimide film by thermally curing a polyimide precursor; and a method for manufacturing a wiring board, wherein the polyimide precursor has a general formula (in formula (1), Rs 2 , R 2 , Ar 1 and Ar 2 . is the same as above.) Provided is a method for manufacturing a wiring board, characterized in that the wiring board is made of a polyamic acid ester represented by:

The present invention also includes a step of creating a homogeneous mixture of a polyimide precursor and a fine metal powder.

A method for producing a metal/polyimide mixed composition, comprising the steps of: dissolving the mixture in an organic solvent; and heating the organic solvent and then thermally curing the polyimide precursor to form a polyimide film. Therefore, the polyimide precursor has the general formula % (in formula (1), R1t R2g A r t and Ar
2 is the same as above. ) Provided is a method for producing a metal/polyimide mixed composition characterized by being a polyamic acid ester represented by:

The present invention also includes a first step of producing wiring made of a copper film on a substrate having electrical insulation properties.

A second step of applying a varnish containing a dissolved polyimide precursor onto the copper film; A third step of thermally curing the varnish to form a polyimide film; and forming through holes in the thermally hardened polyimide film. a fourth step; and a fifth step of forming a copper wiring on the through hole. OR2 (In formula (i), Rt HRz g A r L and A
rz is the same as above. ) The present invention provides a method for manufacturing a multilayer wiring board characterized by being made of a polyamic acid ester represented by the following.

The present invention also includes a first step of producing a wiring made of a copper film on a substrate having electrical insulation properties, a second step of applying a varnish in which a polyimide precursor is dissolved on the copper film, and a third step of thermally curing the varnish to form a polyimide film; a fourth step of forming a through hole in the thermally hardened polyimide film; a fifth step of forming a copper wiring on the through hole; following the step, repeating the second to fifth steps to form a multilayer wiring having a desired number of layers; Provided is a method for producing a multilayer wiring board characterized by being a polyamic acid ester represented by the general formula % (in formula (1), R1, RZ, Art and Arz are the same as above). It is something.

It is preferable that the number of carbon atoms in Rz and R2 described above is 1 or more and 20 or less.

Moreover, the gold R/polyimide wiring board, which is one of the present invention,
It is manufactured using the following process. A gold GC 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. On top of that, a polyimide precursor varnish is applied and cured, and a through-hole pattern is formed using photolithography. Here, as a method for etching polyimide, a wet etching method using hydrazine or the like, or a dry etching method using oxygen gas ions or the like is used.

Furthermore, 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 process, a multilayer wiring board can be obtained. Of course, it can also be used in the form of a single layer of wiring insulated with a polyimide film without multilayering.

Furthermore, a composition in which metal powder is dispersed in a polyimide precursor is useful as a conductive paste.

However, when ordinary polyimide is used and silver or copper is used as the metal, there is a problem that the polyimide decomposes during high-temperature heat treatment. The present invention is also useful for this purpose. This is 1
It is obtained by mixing powders of copper, silver, or their alloys into a solution of the polyimide precursor of the present invention, and exhibits extremely high conductivity after being heated and hardened.

The metal powder can be spherical, scaly, or branch-shaped, and the particle size is 0.1 to 10 Jim to ensure ease of mixing and to avoid problems with sedimentation during hardening during storage. From the viewpoint of subsequent electrical conductivity, 65 to 85% by weight after curing is desirable.

The polyamic acid ester varnish of the present invention can be obtained by heating a polyamic acid obtained by homopolymerization of an aminodicarboxylic acid derivative or by reacting an aromatic diamine with a tetracarboxylic acid derivative in a solvent or by reacting it with a dehydrating agent. .

Examples of tetracarboxylic acid derivatives include esters.

There are acid anhydrides and acid chlorides.

The use of acid anhydrides is preferable in terms of synthesis because the reaction with diamines is easy.

In the synthesis reaction of polyamic acid, - in the shell, N-methylpyrrolidone (NMP), dimethylformamide (DMF)
), dimethyl acetamide (DMAC), dimethyl sulfoxide (DMSO), dimethyl sulfate, sulfolane, butyllactone, cresol, phenol, halogenated phenol, cyclohexanone, dioxane, tetrahydrofuran, acetophenone, etc. at -20
It is carried out in the range of ~+200'C.

Specific examples of aminodicarboxylic acid derivatives used in the present invention include 4-aminophthalic acid, 4-amino-5
-methyl phthalic acid, 4-(p-aniline)-phthalic acid,
Examples include 4-(3,5-dimethyl-4-anilino)phthalic acid, or esters, acid anhydrides, and acid chlorides thereof.

Aromatic diamines used in the present invention include p-phenylenediamine (p-PDA), 2,5-diaminotoluene, 2,5-diaminoxylene, and diaminoxylene (2,3,5,6-te-1-diamin). methylphenylenediamine), 2,5-diaminobencitrifluoride, 2,5-
Diaminoanisole.

2,5-diaminoacetophenone, 2,5-diaminobenzophenone, 2,5-diaminodiphenyl, 2,5-
Diaminofluorobenzene, benzidine, oh-lysine (
o-TLD), m-tolidine, 3.3', 5.5'
-tetramethylbenzidine, 3,3'-dimethoxybenzidine, 3,3'-di(trifluoromethyl)benzidine, 3,3'-diacetylbenzidine, 3,3'-difluorobenzidine, octafluorobenzidine, 4,41
-Diaminoterphenyl (DATP), those having a linear conformation such as 4.4''-diaminoquaterphenyl, and m-phenylenediamine.

4.4'-diaminodiphenylmethane, 1.2-bis(
Aniline) ethane, 4,4'-diaminodiphenyl ether (DDE), diaminodiphenylsulfone, 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, diaminobencitrifluoride, 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-aminophenoxy)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
-amino 2-trifluoromethylphenoxy)benzene,
4,4'-bis(4-amino-2-trifluoromethylphenoxy)biphenyl, 4,4'-bis(4-amino-3
-1-lifluoromethylphenoxy)biphenyl.

4.4'-bis(4-amino-2-trifluoromethylphenoxy)biphenylsulfone, 4,4'-bis(3-
Amino-5-trifluoromethylphenoxy)biphenylsulfone, 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)tetradecafluorohbutane, general formula (Rs and R7 are divalent organic groups, R4 and R (l is a monovalent organic group, and Peq is an integer greater than 1).

Examples of the tetracarboxylic acid derivatives used in the present invention include pyromellitic acid (PMDA), methylpyromellitic acid, dimethylpyromellitic acid, di(trifluoromethyl)pyromellitic acid, and 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 ether, 2
,3゜3',4'-tetracarboxydiphenyl ether,3.3',4.4'-tetracarboxybenzophenone (BTDA),2,3.3',4'tetracarboxybenzophenone,2, 3,6°7-Te1
-Lacarboxynaphthalene, 1,4,5゜7-titracarboxynaphthalene, 1,2,5゜6-thitracarboxynaphthalene, 3.3', 4゜4'-tetracarboxydiphenylmethane, 2゜3.3 ',4'-tetracarboxyphenylmethane, 2,2-bis(3,4-dicarboxyphenyl)propane, 2,2-bis(3,4
-carboxyphenyl)hexafluoropropane, 3,3
'4.4'-Tetracarboxydiphenyl 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, cyclopentanetetracarboxylic acid Examples include acids.

These acid anhydrides, acid chlorides, esters, etc. can also be used.

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

The polyamic acid ester used in the present invention has excellent solubility, low viscosity of varnish,
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 the spin-coding method, which is used in the film.

When forming a polyimide film, the polyamic acid ester is first dried at a temperature of 50 to 250°C, and then dried at a temperature of 250 to 40°C.
It is preferable to perform thermal imidization by heating to about 0°C.

In the present invention, in order to further improve the adhesion between polyimide and various base materials, the surface of the base material may be roughened or
Preferably, the surface is treated with a silane coupling agent, a titanate coupling agent, aluminum alcoholate, aluminum chelate, zirconium chelate, aluminum acetylacenate, or the like.

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

In the polyamic acid ester used in the present invention, when the polyimide skeleton has a linear conformation, the coefficient of thermal expansion of the coating film becomes extremely small and the modulus of elasticity becomes large. Furthermore, the polyamic acid ester used in the present invention can be mixed with inorganic, organic, or metal powders, fibers, chopped strands, etc. to lower the thermal expansion coefficient, increase the elastic modulus, and further control the fluidity. You can do that.

[Effect]

The present invention has discovered that when a polyimide film is formed by contacting copper or silver, the metal dissolves in the carboxylic acid in the polyamic acid precursor, and becomes a catalyst for thermal decomposition under high temperature conditions during curing. A polyimide precursor in which carboxylic acid is masked with an ester group is used to prevent the metal from dissolving.

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

〔Example〕

Example 1 s-B PDA and methanol were reacted 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 form an acid chloride, and then triethylamine and DDE were added and reacted for 2 hours at room temperature and 50°C for 2 hours, and then poured into a large amount of water to obtain the desired alkyl polyamic acid. An ester was obtained.

After drying this polyamic acid alkyl ester.

This polyamic acid alkyl ester varnish was again dissolved in NMP to obtain a 15% varnish, and this polyamic acid alkyl ester varnish was spin-coded onto the surface of a silicon wafer on which a thin copper film had been deposited to form a coating film with a thickness of 10 μm.

Thermal imidization conditions were 100°C for 30 minutes, 100-350°C.
The temperature was raised over a period of 1 hour, and maintained at that temperature for 30 minutes. The atmosphere is in the air. This polyimide film was peeled off from the silicon wafer, and the nine colors of copper content, thermal decomposition temperature, and tensile strength of the film were measured. As a result, it was found that this film contained only 0.05% copper as measured by atomic absorption spectrometry, and the color of the film was yellow-orange, which was almost the same as the film formed on the inert Si○2 film. Ta. The decomposition temperature of this film in air is 450°C, the tensile strength is 105 MPa, and the elongation at break is 35%.
It turned out to be an extremely excellent polyimide film.

Example 2 BTDA and ethanol were combined with N-2-methylpyrrolidone (
The mixture was reacted at a molar ratio of 1:2 in NMP (abbreviated as NMP) to obtain a half-esterified product. p-PDA was mixed with this, and 1.2 times the mole of disylulohexine luposiimide was added to the amino group to cause condensation polymerization. This 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 is applied again.
This polyamic acid alkyl ester varnish was spin-coded onto the surface of a silicon wafer on which a copper thin film was deposited, in the same manner as in Example 1, to form a coating film with a thickness of 10 μm. The imidization conditions by heating are the same as in Example 1. This polyimide film was peeled off from a silicon wafer by etching the copper foil, and the copper content, thermal decomposition temperature, and tensile strength of the film were measured. As a result, this film contained only 0.03% copper, and the color of the film was yellow-orange, containing inert 5iOz.
It is almost the same as a film formed on a membrane. The decomposition temperature of this film in air is 450°C, and the tensile strength is 250 MPa.

It has excellent heat resistance and mechanical properties with an elongation at break of 13%.

Example 3 The polyamic acid alkyl ester varnish of Example 2 was
A coating film with a thickness of 10 μm was formed by spin coding on the surface of a silicon wafer on which a thin silver film was deposited. Thermal imidization conditions were the same as in Example 1 in air. This polyimide film was peeled off from a silicon wafer, and the silver content in the film was determined to be 2 colors, the thermal decomposition temperature, and the tensile strength to be 41.

As a result, this film contained only 0.011% silver as measured by atomic absorption spectrometry, and the color of the film was yellow-orange, almost the same as the film formed on the inert Si○2 film. The decomposition temperature of this film in air is 455°C, the tensile strength is 260 MPa, the elongation at break is 19%, and it has excellent heat resistance and mechanical properties.

Comparative Example I DAPP and BTDA were reacted in cresol at room temperature to form a polyamic acid, and then reacted at 150° C. for 3 hours to obtain an imidized varnish.

This imidized varnish was spin-coded onto the surface of a silicon wafer on which a thin copper film was deposited to form a coating film with a thickness of 10 μm. Heat drying conditions are 150”C 30 minutes, 150~
The temperature was raised to 350° C. over 1 hour and maintained at this temperature for 30 minutes. The atmosphere is in the air. This polyimide film was peeled off from a silicon wafer, and the copper content in the film was measured in two colors and the thermal decomposition temperature.

Tensile strength was measured. As a result, this film contained only 0.03% copper as measured by atomic absorption spectrometry, and the color of the film was yellow-orange, almost the same as the film formed on the inert 5iOz film. Decomposition temperature in air is 410℃, tensile temperature is 120MP
a. The elongation at break is ↓0%.

In addition, after being immersed in a copper etching solution for about 5 hours, the thermal decomposition temperature and mechanical properties of the film were measured and showed almost the same values as those not immersed in the etching solution, indicating that it is extremely stable chemically. I found out that it was.

However, when compared with Comparative Example 2, which will be described later, it is considerably inferior in heat resistance and mechanical properties. This is not due to deterioration of the polyimide, but if the solubility in solvents is improved, the molecular skeleton becomes flexible and inferior in terms of heat resistance and mechanical properties.

Comparative Example 2 P-
1 of N-methyl-2-pyrrolidone (abbreviated as NMP) of polyamic acid obtained from PDA and s-B PDA
The 5% solution was spin-coded to form a coating film with a thickness of 10 μm. Thermal imide conditions are the same as in Example 1. This was peeled off from the silicone filter and its color, thermal decomposition temperature, and tensile strength were measured. As a result, this film has a yellow-orange color with a decomposition temperature of 510°C in air and a tensile temperature of 35°C.
It can be seen that it has very excellent heat resistance and mechanical properties, with an elongation at break of 0 MPa and 25%.

Also, the copper content in this film was naturally very low, less than 0.0003''%.

In addition, after being immersed in a copper etching solution for about 5 hours, the thermal decomposition temperature and mechanical properties of the film were measured, and the results showed almost the same values as those of the film not immersed in an etching solution.
It is also chemically very stable.

It can be seen that if it is imidized without coming into contact with copper or silver, it has very excellent physical properties.

Comparative Example 3 A copper foil film was formed on a silicon wafer by vapor deposition in the same manner as in Example ①, the pattern was formed by etching, and the same polyamic acid varnish as in Comparative Example 2 was applied thereon. It was thermally imidized. As a result, the polyimide film on the copper pattern turned black and brown, and when it was attempted to be peeled off from the silicon wafer, it tore off from the discolored portion of the copper pattern. Similarly, after copper was vapor-deposited on a silicon wafer, a polyamic acid varnish was applied and thermally imidized after forming a pattern. Thereafter, the film was peeled off by immersing it in a copper etching solution. The copper content in this film was very high at 0.3%. The thermal decomposition starting temperature of this polyimide film is 330℃
The heat resistance is nearly 200℃ lower than that of a film formed on an inert film, and the film strength and breakage resistance are 150MP.
a, it was extremely low at 3%. This is probably due to dissolution of copper due to the presence of carboxylic acid in polyamic acid, which is a polyimide precursor, and oxidative deterioration of imide rings due to copper in the film. Comparative example (comparing with 2.

It is clearly seen that when polyamic acid is thermally imidized in contact with copper, the heat resistance is significantly reduced by the copper.

Comparative Example 4 Instead of the 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 and thermally imidized. The thermal decomposition onset temperature of the NR polyimide film is 400°C, which is still good compared to when it is formed on an fR film, but it is nearly 100°C inferior in heat resistance than a film formed on an inert film, and the film strength is , the elongation at break is also 2.
20 MPa, which was extremely low by 6%. This is probably due to dissolution of silver due to the presence of carboxylic acid in polyamic acid, which is a polyimide precursor, and oxidative deterioration of imide rings by silver in the film. In the case of silver, as with copper, the heat resistance of polyimide is considerably reduced.

Comparative Example 5 The same polyamic acid varnish as in Comparative Example 2 was applied onto a silicon wafer on which a thin copper film had been deposited and thermally imidized. However, the atmosphere for curing and heating was not air, but nitrogen gas mixed with a small amount of hydrogen, that is, a slightly reducing atmosphere.

As a result, there was no change in the polyimide film. The thermal decomposition temperature of the polyimide film peeled off after removing copper by etching is 500°C, which is much higher than when it is thermally imidized in air, and almost as high as when it is cured in the form of an inert film. It was the same. Moreover, the film strength and elongation at break are both 35
0 MPa, 21%, which is slightly higher than that of the polyimide film on the 5iOz film, but it can be seen that it is hardly affected by copper. This is probably because copper is dissolved due to the presence of carboxylic acid in polyamic acid, which is a polyimide precursor, but copper in the film is rendered inactive by heat treatment in a reducing atmosphere.

The present invention can be applied to the method of manufacturing a multi-chip module shown in FIGS. 1 and 2. The copper thin film forming the pattern of the copper wiring 2 is placed on an insulating substrate, a ceramic wiring,
It is obtained on the line substrate 1 by vacuum evaporation. Patterning of copper interconnects is well known in the art. It can be obtained by chemical etching or dry etching.

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

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

Subsequently, a copper thin film is similarly formed in the through-hole portion by a method such as vapor deposition to obtain electrical connection with the underlying copper wiring film. Next, this copper film is etched into a desired pattern to form an upper layer of copper wiring. By repeating the above steps, a multilayer wiring having a desired number of calendars can be obtained. Finally, L
By connecting the SI 4 to multilayer wiring using the solder 5, an LSI mounting board suitable for computers and the like can be obtained.

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

〔Effect of the invention〕

The present invention provides a method for producing a metal/polyimide composite that is free from oxidative deterioration of polyimide films, which has been a problem when applying polyamic acid over copper and curing it. Can be done. Furthermore, compared to the conventional method of thermally curing polyamic acid in a reducing atmosphere, it is possible to provide a method that does not have problems such as running costs.

[Brief explanation of the drawing]

FIG. 1 shows high-density distribution II, which is a specific application example of the present invention.
FIG. 3 is a cross-sectional view of the A substrate. FIG. 2 shows a cross-sectional view of a package substrate for a multi-chip module, which is a specific application example of the present invention. DESCRIPTION OF SYMBOLS 1...Ceramic board, 2...Cu wiring, 3...Polyimide insulation film, 4...Si chip, 5...Solder, 6...Power pin. Figure 1

Claims (1)

[Claims] 1. A method for producing a metal/polyimide composite comprising the steps of applying a polyimide precursor onto a conductive solid metal and thermally curing the polyimide precursor to form a polyimide film. In formula (1), R_1 and R_2 are organic groups having 1 or more carbon atoms, and are the same as each other. may also be different,
Also, Ar_1 is an aromatic group with two substituents, Ar_2
is an aromatic group with four substituents. ) A method for producing a metal/polyimide composite, characterized in that it is a polyamic acid ester represented by: 2. The number of carbon atoms in R_1 and R_2 is 1 according to claim 1.
A method for producing a metal/polyimide composite, characterized in that the ratio is 20 or less. 3. A step of producing 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 step of forming a polyimide film by thermally curing the polyimide precursor. In the manufacturing method of a wiring board having a process, the polyimide precursor has a general formula ▲Mathematical formula, chemical formula, table, etc.▼...(1) (In formula (1), R_1 and R_2 are organic are the same or different from each other,
Also, Ar_1 is an aromatic group with two substituents, Ar_2
is an aromatic group with four substituents. ) A method for manufacturing a wiring board, characterized in that it is a polyamic acid ester represented by: 4. The number of carbon atoms in R_1 and R_2 is 1 according to claim 3.
A method for manufacturing a wiring board, characterized in that the ratio is 20 or less. 5. Creating a homogeneous mixture of polyimide precursor and fine metal powder; Dissolving the mixture in an organic solvent; After heating the organic solvent, thermosetting the polyimide precursor. In the method for producing a metal/polyimide mixed composition having a process of forming a polyimide film by, , R_1 and R_2 are organic groups having 1 or more carbon atoms, and may be the same or different from each other,
Also, Ar_1 is an aromatic group with two substituents, Ar_2
is an aromatic group with four substituents. ) A method for producing a metal/polyimide mixed composition, characterized in that it is a polyamic acid ester represented by: 6. The number of carbon atoms in R_1 and R_2 is 1 according to claim 5.
A method for producing a metal/polyimide mixed composition, characterized in that the ratio is 20 or less. 7. A first step of producing a wiring made of a copper film on an electrically insulating substrate, a second step of applying a varnish containing a dissolved polyimide precursor onto the copper film, and thermosetting the varnish. a third step of forming 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. In the method of It doesn't matter if it's one or the other,
Also, Ar_1 is an aromatic group with two substituents, Ar_2
is an aromatic group with four substituents. ) A method for manufacturing a multilayer wiring board characterized by being made of polyamic acid ester represented by: 8. The number of carbon atoms in R_1 and R_2 is 1 according to claim 7.
A method for manufacturing a multilayer wiring board, characterized in that the number is greater than or equal to 20 or less. 9. A first step of producing a wiring made of a copper film on an electrically insulating substrate, a second step of applying a varnish containing a dissolved polyimide precursor onto the copper film, and thermosetting the varnish. a third step of forming 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; following the fifth step. forming a multilayer wiring having a desired number of layers by repeating the second to fifth steps; and a method for manufacturing a multilayer wiring board, wherein the polyimide precursor has a general formula ▲ mathematical formula, chemical formula , tables, etc. ▼ (In 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,
Also, Ar_1 is an aromatic group with two substituents, Ar_2
is an aromatic group with four substituents. ) A method for manufacturing a multilayer wiring board characterized by being made of polyamic acid ester represented by: 10. The method for manufacturing a multilayer wiring board according to claim 9, wherein the number of carbon atoms in R_1 and R_2 is 1 or more and 20 or less.