JPS63301589A - Manufacture of conductive circuit board - Google Patents

Abstract

PURPOSE:To facilitate manufacturing a highly accurate conductive circuit board with a high productivity by a method wherein a polymer layer of a circuit pattern shape is formed in a polymer thin plate up to the middle of its thickness and a plated film is formed with the polymer layer as a core of plating. CONSTITUTION:A polymer thin plate with a thickness of 10-100mum is brought into contact with an active electrode which has a conducting part forming a conductive circuit pattern. Electrolyte containing aromatic compound monomer with heteroatoms is provided between the active electrode and a facing electrode and, by applying a current, a polymer layer with a thickness of 0.1-5mum is formed in the polymer thin plate brought into contact with the active electrode from the contact surface with the conducting part toward the inside of the plate. Then, after the polymer thin plate is peeled off from the active electrode, a plated film is built up on the part of the polymer thin plate where the polymer layer is formed. With this constitution, the conductive circuit pattern can be formed on the polymer thin plate without degrading the accuracy of the circuit pattern formed on the active electrode and, moreover, an excellent productivity can be obtained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to a thin polymer plate that can be used for printed circuit boards (particularly flexible printed circuit boards (FPC)), film connectors, wiring boards, sheet switches, etc. The present invention relates to a method of manufacturing a conductive circuit board on which a highly accurate conductive circuit is formed.

<Prior Art> Conventionally, the following methods have generally been used to manufacture conductive circuit boards. That is, a metal thin film layer is provided on a polymer thin plate such as a plastic film, a conductive circuit-shaped resist layer is provided on the metal thin film layer, and then the metal thin film layer is patterned by etching.
Finally, the resist layer is peeled off to obtain a conductive circuit board. In the above method, methods for providing a patterned resist layer include a photo process method and a printing method.

The photoprocess method is a method in which a photoresist material is applied over the entire surface of a metal thin film layer and then patterned by light irradiation.

Moreover, the printing method is a method of patterning and forming a resist material on a metal thin film layer.

Among these methods, the photoprocess method uses light and has high resolution, making it suitable for manufacturing high-precision conductive circuit boards.
Due to the nature of its manufacturing process, it is unsuitable for continuous production, has high production costs, and has the drawbacks of poor mass productivity.

Further, although the printing method is excellent in mass production, there is a limit in pattern accuracy, and it is usually possible to manufacture only a pattern with a minimum line width of about 100 μm.

As a manufacturing method for conductive circuit boards that solves these drawbacks, there is a method using electrolytic polymerization (Japanese Patent Laid-Open No. 62-2
In this method, a working electrode having a conductive part exhibiting a pattern of a conductive circuit is brought into contact with a thin polymer plate, a counter electrode is placed on this, and an electrolytic solution is placed between the working electrode and the counter electrode. The polymer is formed in the part of the thin polymer plate that is in contact with the conductive part by filling the polymer with a molten metal and passing an electric current between the working electrode and the counter electrode, and then, if necessary, the conductive material formed by the polymer is In order to reinforce the circuit, a conductive circuit was formed on the polymer thin plate by plating the portion where the polymer was produced.

<Problems to be Solved by the Invention> However, the method of manufacturing a conductive circuit board using electrolytic polymerization described above still has the following problems.

Formation of a polymer by electrolytic polymerization occurs from the portion of the surface of the polymer thin plate that comes into contact with the conductive portion of the working electrode, and progresses toward the interior of the polymer thin plate over time. However, since aromatic compound monomers having heteroatoms are dispersed within the thin polymer plate, electrolytic polymerization tends to proceed not only perpendicularly to the working electrode but also parallel to the contact surface. Therefore, when attempting to form a conductive circuit using a polymer in a thin polymer plate, electricity must be applied until the formed polymer becomes sufficiently conductive, which means that parts other than those in contact with the conductive part of the working electrode must be energized. Polymers are also formed. In other words, if the desired conductive circuit is highly accurate,
For example, in the case of a conductive circuit having a thin line pattern with a minimum line width of about 1 to 100 μm, there is a drawback that the accuracy of the conductive circuit cannot be sufficiently guaranteed by the polymer.

Therefore, an object of the present invention is to provide a method for manufacturing a highly accurate conductive circuit board in order to solve the above problems.

<Means for Solving the Problems> In order to achieve the above object, the present invention utilizes electrolytic polymerization to form a polymer exhibiting a circuit pattern on a thin polymer plate by plating the polymer. A conductive circuit is formed by forming the polymer to a thickness necessary to function as a core, and then growing a plating film using this polymer as a plating core. That is, the present invention includes a step of contacting a working electrode having a conductive portion exhibiting a pattern of a conductive circuit with a thin polymer plate having a thickness of 10 to 100 μm;
An electrolytic solution containing an aromatic compound monomer having a heteroatom is interposed between the working electrode and the counter electrode, and electricity is applied to the thin polymer plate in contact with the working electrode.
A thickness of 0.1μ from the contact surface with the conductive part toward the inside.
The method is structured so that the steps of forming a polymer of m to 5 μm, peeling off the polymer thin plate from the working electrode, and growing a plating film on the portion of the polymer thin plate where the polymer is formed are performed in order. be.

This invention will be explained in more detail.

The working electrode consists of a conductive part and a non-conductive part, and the conductive part exhibits a desired conductive circuit pattern.

As a method for manufacturing the working electrode, a general fine pattern processing technique such as a photo process method may be used.

The photoprocessing method will be explained below. First, a conductive layer is formed all over the working electrode substrate. Materials for the conductive layer include gold, silver, copper, titanium, aluminum, nickel,
Single metals such as cobalt and tin or various alloys of these metals are used, or composite layers with metal oxides such as tin, indium oxide, and tin oxide are used. Examples of methods for forming the conductive layer include vacuum evaporation, sputtering, chemical plating, printing, and lamination.

Next, a photoresist layer is formed on the conductive layer. Photoresist materials include photocurable or photodegradable photosensitive polymers or compositions containing the same.

Next, a desired conductive circuit pattern is formed on the photoresist layer using a photofabrication method. That is, the photoresist layer is exposed to light through a photomask having a predetermined shape, and the photoresist material is selectively photocured or photodecomposed.

Next, the unexposed or exposed portions of the photoresist material are dissolved or washed away to form a photoresist layer having a predetermined shape, that is, a conductive circuit.

Thereafter, an etching process is performed through the formed photoresist layer to form a conductive layer in the form of a conductive circuit pattern.

Then, by dissolving or washing away unnecessary photoresist layers, a working electrode having a conductive portion exhibiting a pattern of a conductive circuit as an electrode is formed.

Note that it is needless to say that the working electrode may be manufactured using means other than photoprocessing. In addition, in the case of the present invention, unlike the method of manufacturing a conductive circuit board using the conventional photo process method, once a working electrode having a highly accurate conductive circuit pattern as a conductive part is manufactured, it is possible to This can be used repeatedly.9 Next, the step of bringing the working electrode into contact with the polymer plate will be explained. The polymer thin plate having a thickness of 10 to 100 μm is either a membrane, a film, a sheet, or a plate having at least one polymer selected from the following group as a base.

Polyvinyl alcohol, polyvinyl acecool, polyvinyl alcohol ester, polyvinyl alcohol ether, copolymer with vinyl alcohol structure, polyvinylpyrrolidone, vinylpyrrolidone copolymer, polyvinylpyridine, vinylpyridine copolymer, cellulose ester, cellulose ether, den Powdered ester/protein coagulate, polyamide/chitin coagulate/carbohydrate coagulate (carrageenan, alginic acid, glucomannan, galactomannan, pectin, cellulose.

Chemically processed products of starch), polyacrylic acid copolymers, polymethacrylic acid copolymers, polyacrylamide copolymers, melamine resins, urethane resins, urea resins, and phenolic resins.

The easiest way to bring this thin polymer plate into contact with the working electrode is to apply a solution containing the above-mentioned polymer or ink/paint uniformly to the working electrode surface by printing, spraying, coating, etc. Later, there is a method in which the solvent is evaporated to form a polymer thin plate. At this time, air bubbles should not be included or bubbles should not be generated due to evaporation of the solvent.

Another method is to attach a pre-fabricated thin polymer plate to the working electrode. The thin polymer plate may be closely attached to the working electrode by thermocompression bonding or the like. If the thin polymer plate is long, it may be pulled from both ends with rolls or the like to apply tension and bring into contact with the working electrode. Air, gas, dust, etc. entering into the contact surface between the working electrode and the polymer thin plate will be related to the deterioration of the quality of the conductive circuit board, so be careful not to leave a significant amount of these substances or to prevent them from being inserted incorrectly. In addition, a uniform force must be applied to the thin polymer plate to ensure close contact. Note that, if necessary, the above steps may be performed in a reduced pressure chamber using a very small amount of solvent or adhesive at room temperature or under heating.

In particular, when a long film is used as the polymer thin plate, it is easy to continuously produce conductive circuit boards, and it is highly suitable for mass production.

Next, in an electrolytic solution containing an aromatic compound monomer having a heteroatom, a current is passed between the working electrode and the counter electrode to form a polymer on the polymer thin plate6. Install. It is preferable that the counter electrode be disposed to face the working electrode, and the thin polymer plate be positioned between the two electrodes. However, it is not always necessary to configure the thin polymer plate to be located between both electrodes, and a counter electrode may be placed on the back side of the working electrode with which the thin polymer plate is in contact. The material for the counter electrode is metal,
Any metal compound or carbon may be used, but platinum, gold, palladium, white gold, nickel, titanium, molybdenum, stainless steel, graphite,
Materials such as carbon fiber are excellent, and electrodes made of platinum, nickel, titanium, or graphite are particularly convenient.

In order to form a polymer beautifully, the working electrode area/counter electrode area should be 110.5 to 1060, particularly preferably 1/1 to 1/1.
If anything, it is better to increase the area of the counter electrode so that it falls within the range of 3. In addition, the shape of the counter electrode is, if the working electrode is a flat surface, the counter electrode is a flat surface, if it is a curved surface, the counter electrode is a curved surface parallel to this, and if the working electrode is a semi-cylindrical shape, the counter electrode is a semi-cylindrical or It is preferable that the electrode is cylindrical or linear, and if it is spherical, the counter electrode uses the spherical surface.

The counter electrode and the working electrode in contact with the polymer thin plate are preferably placed in a suitable electrolytic bath and immersed in an electrolytic solution.

As the electrolytic solution, a liquid or paste-like mixed solution containing an aromatic compound monomer having a hetero atom, a supporting electrolyte/solvent, and, if necessary, various additives, is used.

As the aromatic compound having a heteroatom, at least one compound selected from the following group may be used.

Aniline, naphthylamine, aminoanthracene, virole, pyrazole, imidazole, triazole, pyridine, diazine, triazine, oxazine, benzopyrrole, benzthiazole, benzpyrazole, benzimidazole, oxadiazole, thiadiazole, aminoazobenzene, carbazole, quinoline, benzoxazole , or a derivative of said compound.

The supporting electrolyte contained in the electrolytic solution is a salt in which at least one anion selected from the following group (1) and at least one cation selected from the following group (2) are combined.

(1) Halogen ion, sulfate ion, nitrate ion, perhydrohalide ion, hydrofluoroborate ion, hexafluorophosphate ion, hexafluoroacetone, hexafluoroantimonate ion, acetate ion, trifluoroacetate ion, par Fluoro fatty acid ion, trifluoromethanesulfonate ion, aromatic sulfonate ion, fluorosulfonate ion.

(2) Hydrogen ion, lithium ion, sodium ion, ammonium ion, quaternary ammonium ion, silver ion, quaternary phosphonium ion, sulfonium ion.

The solvent is of course necessary to dissolve both the aromatic compound containing a heteroatom and the supporting electrolyte, but it also has the role of permeating these into the polymer thin plate and transporting them to the working electrode side. Therefore, the solvent is naturally limited depending on the type of polymer thin plate.

Examples of the solvent include the following alone or a mixture of two or more.

Water, methanol, ethanol, methylene dichloride, ethylene chlorohydrin, chloral, nitromethane, nitroethane, nitropropane, trifluoroethanol, penzotrifluoride, hexafluoroacetone, pentafluoroacetone, O-dichlorobenzene, propatool, Improper tool, butanol, isobutanol,
Secondary butanol, tertiary butanol, phenol, cresol, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, glycerin, tetrahydrofuran, butyrolactone, methyldioxolane, acetonitrile, propionitrile, benzonitrile, dimethyl formaldehyde, dimethyl acetate Cetamide/diethylformamide/tetramethylurea/N
-Methylpyrrolidone, dimethyl sulfoxide, tetramethylene sulfoxide, tetramethylene sulfone, acetone, methyl ethyl ketone, acetylacetone, propylene carbonate, butylene carbonate, glycol monomethyl ether, glycol dimethyl ether, dimethyl sulfate.

By doing so, the aromatic compound monomer having a heteroatom in the electrolyte is incorporated into the polymer thin plate.

Note that the lower the viscosity of the electrolyte, the easier it is to use, but depending on the conditions of use it may be used in the form of a paste. It is preferable to mix an appropriate amount of a filler such as an inert neutral salt or an insoluble compound such as aerosil silica, aerosil alumina, carbon black, etc. with the electrolytic solution to form a paste.

Next, by passing current between the working electrode and the counter electrode, the aromatic compound monomer having heteroatoms is electrolytically oxidized and polymerized to form a polymer in the polymer thin plate. This energization may be carried out immediately after the electrolytic solution is brought into contact with the thin polymer plate, or may be carried out after the aromatic compound monomer having the heteroatom is sufficiently incorporated into the thin polymer plate. .

At this time, the layer thickness of the polymer is important, especially in order to obtain a highly accurate pattern. In other words, in the process of forming a conductive circuit made of a polymer on a thin polymer plate, the formation of polymer occurs from the surface of the thin polymer plate in the part that is in contact with the conductive part of the working electrode, and as time passes, the polymer forms inside the thin polymer plate. progress towards.

However, since aromatic compound monomers having heteroatoms are dispersed in the polymer thin plate, polymerization progresses not only perpendicularly to the contact surface between the conductive part of the working electrode and the polymer thin plate, but also along the contact surface. This can also occur in parallel directions. Therefore, if the thickness of the polymer becomes thicker than 5 μm, the polymer will be formed in areas other than those in contact with the conductive portion of the working electrode, resulting in poor accuracy. On the other hand, if the polymer layer thickness is less than 0.1 μm, a sufficient plating film cannot be grown in the subsequent plating process. However, if the polymer layer thickness is approximately 0.1 μm to 5 μm
If so, the above problem can be solved.

Incidentally, when aromatic compound monomers having heteroatoms are formed by electrolytic oxidative polymerization, they usually have considerable electrical conductivity, but in the case of this invention, only the ability to form plating is required; There's no need to have it.

One method for achieving this layer thickness within the above range is to control the time during which the current is applied. That is, the current application time is 0.1 to 300 seconds, particularly preferably 0.1 seconds.
If the time is set to 60 seconds, the above thickness ratio can be satisfied. Of course, in order to electrolytically polymerize an aromatic compound monomer having a heteroatom, it is necessary to adjust the voltage and current, and in the case of DC voltage, it is 0.1 to 10V, particularly preferably 1 to 3V, and the current density is 0. 1~50mA/cm
2, particularly preferably 1 to 20 mA/cm2. In addition, in the case of AC voltage, it is 1 to 15V, and the current density is 0.1 to 15V.
It is IA.

Note that the step of forming the polymer described above is not necessarily performed in an electrolytic cell, but can also be performed outside the electrolytic cell. In other words, when the counter electrode and the working electrode in contact with the polymer thin plate are installed outside the electrolytic cell, the gap between the two electrodes is completely filled with liquid or paste electrolyte, and the gap is filled from the side of the gap. The side surface may be sealed using a backing or the like to prevent the electrolyte from leaking outside.

Next, the polymer thin plate is peeled off from the working electrode. First, the electrolytic solution is removed from the polymer thin plate, and if necessary, the adhering electrolyte is washed with water or an organic solvent, and then the polymer thin plate is peeled off without tearing.

After such a peeling operation, the thin polymer plate is washed by immersing it in water or an organic solvent, if necessary, to remove unnecessary substances, and then dried.

Next, a plating film is grown on the portion of the thin polymer plate where the polymer is formed.

Conventional plating methods such as electroless plating and vapor phase plating can be used for plating. The optimum plating conditions can be selected depending on the polymer manufacturing method, the type of polymer thin plate, etc.

- Explain electroless plating as an example. The metals used to form the plating film through electroless plating include nickel, cobalt, copper, silver, iron, tungsten, manganese, palladium, vanadium, tin, and zinc, which can be used singly or in combination of two or more. be done. As a plating solution, a sulfuric acid steel bath (for example, CuSO
4.514207g/l -EDTA-4Na 13g
/l -HC)103.9g/l -NaOH4g/l
-Polyethylene glycol (M, W, 3,000-3
, 700) 0.1%). For nickel plating, a bath using hypophosphite as a reducing agent (e.g. Ni2S) is used.
O4・7H2053g/l・Ammonium citrate 97
g/I -NaH2PO2106g/l -pH10)
, a bath using a boron hydroxide compound as a reducing agent (e.g. N
i2SO4・7H2030g/I・sodium malonate 34g/I-dimethylamineborane 0.06mol/1
- pH 5,1 to 6.0), a bath using hydrazine as a reducing agent (e.g. NiCh 5 g/l, sodium tartrate 4
．． 6g/l-NzH4・HCl103g/I・p)1
10).

The conductive circuit board of the present invention prepared as described above may be surface coated with a resin liquid or laminated with a resin film, if necessary.

<Example> Examples of the method for manufacturing a conductive circuit board of the present invention will be described in detail below.

Inukami JLL After depositing copper to a thickness of 0.1 μm on a glass substrate, a photoresist was applied and exposed to ultraviolet light through a photomask. Thereafter, etching was performed to dissolve and remove the photoresist, thereby obtaining a working electrode having a striped pattern of conductive portions with a line width of 10 μm and a pitch of 50 μm. A polyethylene (PE)-polyvinyl alcohol (PVA) copolymer (PE/PVA=7
A mixed solution of 0/30) water and n-propyl alcohol was applied and dried at 130°C for 2 hours to form a 30% thick solution on the working electrode.
A micromolecular polymer thin plate was formed.

A platinum plate is used as a counter electrode, and the distance between the working electrode and the counter electrode is 1.
．． It was installed in an electrolytic cell in parallel at 0 cm. The height of the electrolytic cell is 1
It has a cylindrical shape with a diameter of 5c+n and 4cm, and the electrolytes are 0.1M aniline' and 0.1M aniline'. It was an aqueous solution containing IM hydrochloric acid.

After applying a direct current with a voltage between the electrodes of 1.6 V to the electrodes installed in the electrolytic cell for 60 seconds, the working electrode was pulled up and washed with ion-exchanged running water for 5 minutes, after which the thin polymer plate was peeled off. Then, it was further immersed in methanol for 2 minutes and ion-exchanged water for 3 minutes, and then carefully attached to a glass plate and dried with warm air. After drying, the thin polymer plate was peeled off from the glass plate and cut, and the layer thickness of the formed polyaniline was measured and found to be about 7 μm. Further, the resistance value was 6×10 −33 /cm.

Next, the polymer thin plate was soaked in an electroless copper plating solution at 70°C for 2 hours.
Immersed for minutes, line width 11.5 μm, conductivity 0.38/cm
A conductive circuit board was obtained by attaching a copper plating film.

The composition of the plating solution was as follows.

Cu5O,i ・5H200,03mol/lNaO
80,10mol/1)(CHOO,23mol/I EDTA O,04mol/1
2,9-dimethyl-1,10-phenanthroline
80mg/January 2 Vertical LL Example 1 by changing the energization time from 60 seconds to 5 minutes
When electricity was applied in the same manner as above, a conductive circuit board with a line width of 30 to 60 μm was obtained.

In this case, the layer thickness of the polymer formed in the polymer thin plate is 3
It was 0 μm and reached the back side of the polymer thin plate.

When plating was carried out in the same manner as in Example 1 by changing the current application time from 60 seconds to 300 seconds, the line width was approximately 18
A μm conductive circuit board was obtained. In this case, the layer thickness of the polymer formed in the polymer sheet was 25 μm. From the above, it was found that when the layer thickness of the polymer exceeds 20 μm, pattern accuracy deteriorates.

Hu1 Ren2 Instead of the PE-PVA copolymer, a 20 μm thick polyvinyl chloride (molecular weight approximately 63,000) polymer thin plate was used, and the electrolyte contained 0.5 M pyrrole and 0.5 M pyrrole. Using an acetonitrile solution containing IM's tetraethylammonium perchlorate, a direct current with a voltage of 2.0 V between the electrodes was applied for 90 seconds using the electrode and electrolytic cell of Example 1.
A conductive circuit board having a polypyrrole film thickness of about 10 μm, a line width of about 11 μm, and a conductivity of 0.88/cm was obtained.

<Effect of the invention> This invention has the following excellent effects.

In this invention, a polymer is formed halfway through the thickness of a thin polymer plate in the form of a circuit pattern, and then a plating film is formed using this polymer as a plating nucleus, so that a conductive circuit board with higher precision can be produced. can be manufactured with high productivity. That is, a conductive circuit pattern can be formed on a thin polymer plate without substantially impairing the accuracy of the circuit pattern formed on the working electrode. Furthermore, due to the characteristics of the manufacturing method, it is suitable for continuous production and has excellent productivity.

Patent applicant: Nissha Printing Co., Ltd. Hand continuation supplementary correction d (spontaneous) 7-゛ May 1, 1986

Claims (1)

[Claims] A method for manufacturing a conductive circuit board, characterized by performing the following steps in order. (a) A step of contacting a working electrode having a conductive portion exhibiting a pattern of a conductive circuit with a thin polymer plate having a thickness of 10 to 100 μm. (b) An electrolytic solution containing an aromatic compound monomer having a heteroatom is interposed between the working electrode and the counter electrode, and electricity is applied to the thin polymer plate in contact with the working electrode to form the conductive portion. Thickness 0 from the contact surface to the inside
．． Step of forming a polymer of 1 μm to 5 μm. (c) Peeling the polymer thin plate from the working electrode. (d) A step of growing a plating film on the portion of the polymer thin plate where the polymer is formed.