JPH0318755B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a new conductive circuit board and its manufacture, and its purpose is for use in printed circuit boards, film connectors, wiring boards, or sheet switches. The aim is to produce high-quality substrates with precise conductive circuit patterns such as these and provide them to the market as materials for industrial use, industrial use, daily necessities, etc.

<Prior art and problems to be solved by the invention> Conventionally, conductive circuit boards have been produced by printing methods, photoresist etching methods, masking vapor deposition methods, laser etching methods, chemical dissolution methods, etc. Various difficulties in precision, productivity, economic efficiency, and technical aspects always appear in each of them, and when it comes to particularly complex or minute designs, no matter which known manufacturing method is used, precision, The drawback is that it is difficult to consistently produce beautiful, high-quality products. The present inventor has been conducting research for many years on a new method to solve these drawbacks all at once, and has now finally completed the surprising invention.

<Means for Solving the Problems> In other words, the present inventors have proposed a method for forming a heterogeneous film on an electrode base material in which a photoresist layer is formed by removing only a desired circuit pattern portion on a base body on which a metal plate or a metal thin film is formed. A circuit pattern formed by electrolytic polymerization of an aromatic compound having atoms is formed in a thin plastic plate, and a metal layer is formed only on the circuit pattern by electrolytic plating. A step of obtaining an electrode base material in which a photoresist layer is formed by removing only a desired circuit pattern portion on a conductive circuit board and a base material on which a metal plate or metal thin film is formed, a photoresist layer of the electrode base material. A step in which a thin plastic plate is closely attached to the surface on which a A process of filling a liquid or pasty electrolyte made of a polar organic solvent, a process of applying electricity between the electrode base material and the electrode to electrolyze and forming a circuit pattern in a thin plastic plate, and a process of forming a circuit pattern in a thin plastic plate as an electrode. a step of separating from the base material and the electrolyte;
The present invention has invented a method for manufacturing a conductive circuit board characterized by comprising a step of bringing a thin plastic plate into contact with a plating solution and performing electroplating to form a metal layer only on the circuit pattern.

First, a photoresist layer for forming a conductive circuit pattern is provided on a metal plate or metal thin film. As the material for the metal plate or metal thin film, a single metal such as gold, silver, copper, aluminum, or nickel, an alloy of the metals, or a metal oxide such as indium oxide or tin oxide is used. When forming a metal thin film on a substrate, vacuum evaporation method, sputtering method, CVD method,
Apply chemical plating method etc. For the photoresist layer formed on the metal plate or metal thin film, a commercially available photosensitive photopolymer may be used. Methods for forming the photoresist layer include coating methods, spraying methods, printing methods, and the like.

Next, a circuit pattern is formed on the photoresist layer by a photoablation method. That is, the photoresist layer is exposed to light through a photomask exhibiting a predetermined circuit pattern, and the photoresist layer is selectively baked, photocured, or photodecomposed. Next, the photoresist layer in the unexposed or exposed areas is removed by dissolving or washing away. In this way, a photoresist layer is formed from which only the circuit pattern portion is removed, and an electrode base material is obtained. Therefore, the surface of the metal plate or metal thin film is exposed in the circuit pattern portion.

Next, we will describe the process of closely adhering a thin plastic plate to the surface on which the photoresist layer of the electrode base material prepared based on the above considerations is formed. First of all, plastic thin plate is made of polyvinyl chloride, polyvinylidene chloride, vinyl chloride copolymer, polyvinyl fluoride, polyvinylidene fluoride, polyester, polyamide, polyvinyl ether, polyalkylene ether, polyether ester, Either a membrane, film, sheet or plate based on at least one solvent-resistant polymer selected from the group consisting of chlorinated polyolefin, polyamideimide, polyethersulfone, polyimide, polyamino bismaleimide, polysulfone, and polystyrene. be.

The easiest way to adhere this thin plastic plate is to uniformly adhere a solution, ink, or paint containing this plastic to the surface of the metal plate or thin metal film by printing, spraying, coating, etc. This is a method of forming a thin plate by evaporating a solution, but at this time, there must be no air bubbles or foaming due to evaporation of the solvent. On the other hand, adhesion to the surface of a metal plate or metal thin film should be carried out in a reduced pressure chamber, if necessary, in the presence of a very small amount of solvent or adhesive at room temperature or under heating. In this case as well, the contamination of air, gas, solvents, plasticizers, dust, etc. on the contact surface is related to the loss of the product, so care should be taken to ensure that these do not remain significantly or enter by mistake. It is necessary to apply uniform force to the base material on which the thin film is formed so that it adheres closely. Even in this case, if unnecessary internal distortion is left in the metal plate or the base material on which the metal thin film is formed, or if the thickness is uneven, the beautiful formation of the conductive circuit pattern will be hindered. Since there is a high possibility that the thickness will vary, boards that require uneven thickness should be built up in post-processing.

Once the above steps are completed, it is next necessary to install electrodes facing the thin plastic plate. If this thin plate is flat, the counter electrode should be flat; if this thin plate is curved, the counter electrode should be a curved surface parallel to this; if the thin plate is semicylindrical, the counter electrode should be semicylindrical, cylindrical, or If the thin plate has a spherical surface, the counter electrode uses the spherical surface. The thin plate and the counter electrode are usually installed in a suitable electrolytic cell, but when the area of the thin plate becomes large, a spacer or the like is used to maintain a constant gap between the thin plate and the counter electrode in a drying chamber. In any case, it is necessary to fill the thin plate and the counter electrode with a sufficient amount of electrolyte. If an electrolytic bath is used, it is sufficient to immerse it in the electrolyte, or if it is installed in a drying chamber, there is a gap between the two. It is necessary to completely insert and fill the liquid or pasty electrolyte into the gap, and then seal the sides using packing or the like to prevent the electrolyte from leaking out from the gap. The electrolytic solution used here is a liquid or paste-like electrolytic solution consisting of an aromatic compound having a hetero atom, a strong electrolyte, and a polar organic solvent containing no active hydrogen atoms, and the operating temperature of this electrolytic solution is -20°C to +70°C.
The temperature is particularly preferably -10°C to +50°C.

Aromatic compounds having heteroatoms include aniline, nuclear-substituted aniline, naphthylamine, nuclear-substituted naphthylamine, aminoanthracene, nuclear-substituted aminoanthracene, thiophene, nuclear-substituted thiophene, pyrrole, substituted pyrrole, pyrazole, substituted pyrazole, imidazole, substituted imidazole,
Triazole, substituted triazole, pyridine, nuclear substituted pyridine, diazine, substituted diazine, triazine, substituted triazine, oxazine, substituted oxazine, benzothiophene, substituted benzothiophene, benzopyrrole, substituted benzopyrrole, benzpyrazole, substituted benzpyrazole, benzimidazole, substituted benz Imidazole, oxadiazole, thiadiazole, azobenzene, substituted azobenzene, phthalocyanine, nuclear substituted phthalocyanine, carbazole, substituted carbazole, quinoline, nuclear substituted quinoline, benzoxazole, substituted benzoxazole, tetra(naphthylo)tetraazaporphyrin and tetra(phenanthro) At least one compound selected from the group consisting of tetraazaporphyrin.

Strong electrolytes include perhalogenated acid, hydroborofluoric acid, hexafluorophosphoric acid, hexafluoroarsenic acid, hexafluoroantimonic acid, trifluoroacetic acid, perfluorofatty acid, trifluoromethanesulfonic acid, aromatic sulfonic acid, and hexafluoroacetic acid. at least one strong acid anion selected from the group consisting of fluorosilicic acid and lithium salt, sodium salt, ammonium salt, quaternary ammonium salt,
It is a salt in which a cation is combined with at least one salt selected from the group consisting of phosphonic acid, silver salt, quaternary phosphonium salt, and sulfonium salt.

Polar organic solvents containing no active hydrogen atoms include methane dichloride, acetonitrile, propionitrile, benzonitrile, dimethylformamide, diethylformamide, dimethylacetamide, tetramethylurea, N-methylpyrrolidone, N-formylpiperidine, N-acetylpiperidine, N,N-diformylpiperazine, N,N-diacetylpiperazine, dimethylsulfoxide, dimethylsulfone, tetramethylenesulfoxide, tetramethylenesulfone, tetrahydrofuran, glycol carbonate, glycol ether, cyclic lactone, nitrobenzene and hexamethylphosphor at least one aprotic polar solvent selected from the group consisting of lutriamides;

Among the above, economically used aromatic compounds with heteroatoms are aniline, thiophene, bitienyl, pyrrole, methylpyrrole, etc., and strong electrolytes are
LiBF ₄ , LiPF ₆ , LiClO ₄ , R ₄ NPF ₆ , R ₄ NClO ₄ ,
R ₄ NBF ₄ , R ₄ NSO ₃ C ₆ H ₄ R, R ₄ NAsF ₆ , LiAsF ₆
(However, R is a C ₁ to C ₄ alkyl group). Polar organic solvents containing no active hydrogen atoms include acetonitrile, propionitrile, benzonitrile, tetrahydrofuran, propylene carbonate, γ-
Butyrolactone, ethylene glycol dimethyl ether, methyl dioxolane, N-methylpyrrolidone, nitrobenzene, methane dichloride, etc. are inexpensive. The composition of the electrolytic solution of the present invention can be arbitrarily selected in principle, but the ratio of aromatic compound having a hetero atom/strong electrolyte/polar organic solvent containing no active hydrogen atoms (mole amount/mole amount/solvent ml)
is in the range of 0.01 to 1.50/0.02 to 2.00/1000, particularly preferably 0.05 to 1.00/0.03 to 1.5/1000. Note that the lower the viscosity of the electrolyte, the easier it is to conduct electricity, but depending on the conditions of use, it may be pasty. A small amount of an inert neutral salt or an insoluble compound such as aerosil silica is added to prevent the electrolyte from solidifying.

The opposing electrode material used in the present invention may be any metal, metal compound, or carbon, but as a result of testing by the present inventors, platinum,
gold, palladium, white gold, nickel,
titanium, molybdenum, stainless steel,
Graphite or carbon fiber are excellent.
Particularly useful are electrodes made from platinum, nickel, titanium or graphite. The step of electrolyzing by applying electricity between the base material surface and the above-mentioned electrolysis according to the present invention is a DC voltage of 0.1 to 100V,
Particularly preferably 1-30V, current density 0.1-50m
A/cm ² , particularly preferably 1 to 20 mA/cm ² .
The electrolysis operation time is several minutes to several hours. Electrolysis operation time is the time it takes for a circuit pattern to be formed on a thin plastic plate. If it takes a long time, a fairly thick and strong circuit pattern will be formed, whereas a thin line pattern will take a relatively long time. Short-term electrolysis operations should be performed.

The process of forming a circuit pattern on a plastic thin plate starts from the surface of the thin plate that is in close contact with the metal plate or thin metal film as electrolysis progresses, and progresses toward the inside of the thin plate as time passes.

The electrolytic polymerization reaction used in the present invention is
Polymerization is usually initiated by a voltage of several V, which is the oxidation potential of the monomer, and when forming polypyrrole from pyrrole, an electrolytic solution of LiBF ₄ dissolved in CH ₃ CN is used at 3 V, 0.3 mA/cm ² The polymerization reaction progresses in this step. However, when forming polythiophene from thiophene, 20V, 10-20m
A current of A/cm ² is required. The gap between the anode and cathode is
It is approximately 0.5 to 5 cm, and it is desirable that the electrolyte be appropriately mechanically stirred. Since the polymerization reaction occurs on the anode side, care must be taken regarding the material of the anode.
As mentioned above, the material of the cathode is not limited. When it is desired to measure a cyclic voltammogram during polymerization, it is convenient to insert a reference electrode into the electrolyte. In addition, in ordinary electrolytic polymerization of polypyrrole or polythiophene, the polymerization current varies depending on the monomer, electrolyte, and solvent (and their concentrations) even if the same voltage is applied, but the polymerization efficiency is approximately constant for both, 1 coulomb. Hit (0.4~
0.5) × 10 ^-5 mol of monomer is polymerized, approximately 40
~50%. The inventors have also found that, in general, the lower the voltage, the better the efficiency, but when the voltage is increased, the background current increases and the efficiency tends to decrease.

Now, in the electrolytic process of the present invention, the thin plastic plate side is used as an anode and the opposite electrode is used as a cathode, and the desired circuit pattern is formed on the anode side.In order to form a beautiful circuit pattern, the anode surface area/cathode surface area is If anything, it is better to increase the cathode area so that the ratio is in the range of 1/0.5 to 10.0, particularly preferably 1/1 to 3. In this electrolytic polymerization reaction, some of the anions resulting from the dissociation of the electrolyte are incorporated as dopants into the polymeric substance constituting the circuit pattern deposited on the anode side, but the extent depends on the conditions of each process shown above. It's going to change quite a bit. However, it is guaranteed that all the polymeric substances that make up the circuit pattern produced here are electrically conductive. Next, first remove the electrolytic plate from the surface of the plastic thin plate on which the circuit pattern as described above is formed, and if necessary, wash the adhering electrolyte with an organic solvent, and then remove the surface of the metal plate or metal thin film and the photoresist. Peel the thin plate from the surface of the layer without breaking it. After this separation operation, the thin plate is immersed in an organic solvent to be washed to remove unnecessary substances, and then dried. The conductivity of the circuit pattern obtained here is approximately σ = 10 ^-3 to 10 ³ S/cm, but in order to further improve this, a suitable dopant (for example, H ₂ SO ₄ , I ₂ , AlCl ₃ ,
Naturally, doping with InCl ₃ , AsF ₅ , SbF ₅ , etc.) is sufficient.

Furthermore, they succeeded in improving the conductivity of the conductive circuit board by bringing the conductive circuit board prepared as described above into contact with a plating solution and performing electroplating to deposit metal only on the circuit pattern. In other words, the inventor has researched various methods for stabilizing the circuit pattern of the conductive circuit board so as to withstand long-term use and imparting excellent conductivity, and the method has been found to be the most preferable method. It was discovered that the method involved electroplating the circuit pattern.
The metal to be plated is not particularly limited, but the metals used include Al, Cd, Cr, Co, Au, In, Fe,
Among Pb, Ni, Pt, Ag, Su, Zn, etc., particularly industrially important ones are Cu, Au, Ni, Pt, Ag, Co, and various alloys, and metals that are preferably brightly plated. For copper plating, copper cyanide baths (e.g.
CuCN26g/, NaCN35g/, Na ₂ CO ₃ 30
g/, KNaC ₄ H ₄ O ₆・4H ₂ O45g/, PH12.6),
Copper sulfate bath (e.g. CuSO _{4.5H 2} O188g/,
H ₂ SO ₄ 74g/), copper borofluoride bath [e.g. Cu
(BF ₄ ) ₂ 224g/, HBF ₄ 15/1, H ₃ BO ₃ 15g/
, PH1.2~1.7], copper pyrophosphate bath (Cu ⁺⁺ 22~38
g/, P ₂ O ₇ ^---- 150~250g/, NO ₃ ^- 5~10
g/, NH ₃ 1 to 3 g/, PH8.2 to 8.8), etc. are used. For gold plating, a cyanide gold bath (e.g.
Au4.0g/, KCN30g/, K ₂ HPO ₄ 30g/
, _{K2CO3 30g} /, PH11-11.5), etc. are used. For nickel plating, a mixed nickel salt bath (e.g.
NiSO ₄・7H ₂ O240~340g/, NiCl ₂・6H ₂ O30
~60g/, H ₃ BO ₃ 30-40g/, PH2.4), nickel borosilicate bath [e.g., Ni(BF ₄ ) ₂ 220g/
, Ni5.5g/, HBF ₄ 4g/, H ₃ BO ₃ 30g/
, PH2.0-3.5] etc. are used. For silver plating, use a silver cyanide bath (for example, AgCN45g/, KCN4g/
, K ₂ CO ₃ 15 g/, KOH 4 g/), etc. are used. In addition, for tin plating, use a borofusated tin bath (for example, Sn40g/, HBF ₄ 40g/, gelatin 2g/
, β-naphthol 0.5g/), etc. are used.
All of the plating baths shown above are basic, and additives are actually added to complete bright plating. Furthermore, one of the most suitable platings for the present invention is borofluoride bath plating, for example, solder alloy plating includes Sn ⁺⁺ 52 g/, Pb ⁺⁺ 30 g/,
A solution containing 100 to 200 g of HBF ₄ /, 25 g of H ₃ BO ₃ /, and 5.0 g of peptone was used as the anode plate.
This is done using an alloy with Sn/Pb=60/40. The proportions of a typical solder alloy bath (7-93 bath) in this regard are 49.6% Sn (BF ₄ ) ₂ parts 11 kg, 51% Pb
(BF ₄ ) ₂ liquid 121Kg, 4% HBF ₄ 76Kg, H ₃ BO ₃ 7Kg,
It consists of 0.2 kg of peptone and 247 kg of water, and the operating conditions are such that electroplating can be performed at a cathode current density of 20 to 30 mA/cm ² and a temperature of 10 to 50° C. with gentle bath stirring. Copper plating is often performed as a base preparation for other platings, and by plating nickel or a solder alloy on top of that, the circuit pattern becomes extremely strong and its conductivity becomes extremely high. It will improve.

Of course, the substrate whose conductivity has been improved in this manner may be subjected to secondary processing or tertiary processing such as overcoating.

The present inventor conducted numerous experiments regarding the present invention described above and confirmed the novelty and superiority of the present invention. A few specific examples are extracted and shown below as examples. Therefore, the present invention should not be construed as being limited to the examples shown below, and it is of course possible to modify the embodiments as desired without departing from the spirit and spirit of the present invention. It is. The superiority of the present invention will become clearer through the following examples.

<Example> Example 1 Photoresist (commercial product,
After applying FPER (product name: FPER, manufactured by Fuji Pharmaceutical Co., Ltd.),
A pre-prepared photomask is used and exposed to ultraviolet light to print the circuit pattern onto the photoresist surface. Next, the photoresist on the circuit pattern portion is dissolved and removed. On the copper plate on which this photoresist is partially formed, purified polyvinyl chloride with a high degree of polymerization is applied in a solvent (tetrahydrofuran 90% + cyclohexane 10%).
A 5% solution of polyvinyl chloride is applied in a clean room, and nitrogen gas is sent to remove the solvent to form a polyvinyl chloride film with a thickness of 0.1 to 0.2 mm. A copper plate is used as an anode, and a nickel plate is used as a cathode, which are placed facing each other with a gap of about 2 cm from the anode. This is submerged in a dedicator filled with electrolyte, degassed under reduced pressure to create a nitrogen gas atmosphere, and then energized. The electrolyte is 0.2 mol of tetrabutylammonium perchlorate,
It has a composition in which 0.1 mole of pyrrole is dissolved in 1 part of a mixture of butylene carbonate and acetonylyl (1:1), and the temperature is maintained at -15 to -5°C. The electricity is
Test at 2V and 0.6mA/ ^cm2 for 5 to 10 hours. During this operation time, a circuit with the same pattern as the copper circuit is formed on the side of the polyvinyl chloride in contact with the copper plate, and it is observed that this circuit gradually becomes stronger. After pulling it up, immersing it in acetone, cleaning it, and drying it, the polyvinyl chloride film is peeled off from the surface of the copper plate. A circuit similar to the circuit pattern formed with photoresist on the surface of the copper plate is formed on the peeled film.
The circuit pattern made of polypyrrole obtained here has σ=10 to 15 S/cm.

Example 2 A photoresist (commercial product, trade name: OPR, manufactured by Tokyo Ohka Co., Ltd.) was applied to a polyester film with aluminum vapor-deposited to a thickness of about 500 Å, and then exposed to ultraviolet light through a photomask prepared in advance. , print the circuit pattern on the photoresist surface. Next, the photoresist on the circuit pattern portion is dissolved and removed. A very small amount of m-cresol is applied to the aluminum and film surfaces, and an unstretched polyethylene terephthalate film with a thickness of 30 μm is placed thereon, heated to 160 to 180° C., and then pressed to completely adhere. This adhesive was vacuum dried at 100° C., and in the same manner as in Example 1, a counter cathode platinum plate was installed and deposited in an electrolytic solution. The electrolyte is 0.2 mol of benzimidazole in 1 part of acetonitrile,
This is a solution containing 0.4 mole of tetrabutylammonium perchlorate. Current is passed between the electrodes (2V,
3 mA/cm ² ) and kept at 10 to 15° C. for about 40 minutes, a circuit pattern of polybenzimidazole (σ=0.01 S/cm) is formed in the polyethylene terephthalate film in the same manner as the electrode pattern of the aluminum film.
Next, the polyethylene terephthalate film is separated, thoroughly washed with acetonitrile, and then dried to obtain a conductive circuit board.

Example 3 The circuit board used in Example 1 was immersed in a nickel acidic fluoride bath (100% HF43ml basic nickel carbonate tetrahydrate 120g/citric acid 30g/sodium lauryl sulfate 1.0g/), and the circuit board Electrification is applied between the and opposing nickel electrodes (electrical density 50 m
By electrolyzing the solution while stirring the solution ^gently , a circuit board with nickel plated thinly and uniformly on the circuit pattern is obtained, and the nickel plated area has ρ=10 ^-5 .
It was confirmed that Ωcm.

Example 4 The circuit board obtained in Example 2 was heated in a copper cyanide bath (44 g of CuCN/67 g of NaCN/74 g of Lotusel salt).
If the substrate is immersed in KOH (g/g/KOH 11 g/) and operated in the same manner as in Example 3 using opposing copper electrodes, a substrate with copper plating on the circuit pattern side can be obtained. Furthermore, if this is further plated with nickel or alloy by a conventional method, a circuit board with a very strong circuit pattern and rich in chemical resistance and weather resistance can be obtained. The conductivity can be varied depending on the metal to be plated.

<Effects of the Invention> The present invention relates to a conductive circuit board and its manufacturing method, and clarifies a method for easily mass-producing conductive circuit boards useful as electronic materials and electrical materials ranging from industrial parts to general daily necessities. It is open. Examples of the use of the conductive circuit board obtained by the present invention include printed circuit boards, film connectors, sheet switches, sheet coils, sensors, phases, and high-density circuits, and its industrial use value is extremely large. It is something.

Claims (1)

[Claims] 1. Electrolysis of an aromatic compound having a heteroatom on an electrode base material in which a photoresist layer with only a desired circuit pattern removed is formed on a base material on which a metal plate or a metal thin film is formed. A conductive circuit board characterized in that a circuit pattern formed by polymerization is formed in a thin plastic plate, and a metal layer is formed only on the circuit pattern by electrolytic plating. 2. Obtaining an electrode base material in which a photoresist layer is formed by removing only the desired circuit pattern portion on a substrate on which a metal plate or a metal thin film is formed, a step of obtaining an electrode base material on which a photoresist layer is formed by removing only a desired circuit pattern portion, The process of adhering the plastic thin plate, installing an electrode facing the plastic thin plate, and removing an aromatic compound having a hetero atom, a strong electrolyte, and a polar organic solvent containing no active hydrogen atoms between the plastic thin plate and the electrode. a step of filling a liquid or paste-like electrolyte solution; a step of applying electricity between the electrode base material and the electrode to cause electrolysis and forming a circuit pattern in the thin plastic plate;
A conductive circuit comprising the steps of separating a thin plastic plate from an electrode base material and an electrolytic solution, and bringing the thin plastic plate into contact with a plating solution to perform electroplating to form a metal layer only on the circuit pattern. Substrate manufacturing method. 3 The plating liquid is nickel, cobalt, chromium, copper,
Silver, gold, platinum, tin, solder alloys and cobalt.
3. The method of manufacturing a conductive circuit board according to claim 2, wherein the solution is a compound capable of electrochemically depositing at least one metal selected from the group consisting of nickel alloys.