JPH0773158B2 - Circuit board manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a printed circuit board, and more particularly to a method for manufacturing a circuit board by an additive method.

[Prior Art] Conventionally, a method (additive method) for producing a printed circuit board only by chemical copper plating is disclosed in, for example, Japanese Patent Publication No. 40-40221. The method of manufacturing this printed circuit board is as follows.

(A) The following photosensitive resin composition is deposited on a substrate to form a photosensitive resin composition 1) a resin component (main component rubber) 2) a metal of Group 1B and Group 8 of the Periodic Table of Elements, or a salt thereof. , These oxides 3) sensitizers that increase the photosensitivity of the resin component 4) At least one of dyes and pigments that increase the photosensitivity of the resin component 5) Solvent (b) Circuit of this photosensitive resin composition In the form of a mold, the composition is exposed to a light source for curing, (c) developed to remove the unexposed photosensitive resin composition, and (d) the photocured photosensitive resin composition is coated with copper by electroless copper plating. A plating layer is formed.

[Problems to be Solved by the Invention] In the above-mentioned conventional example, since the surface is not roughened even when the resin pattern made of the cured photosensitive resin composition is etched, the adhesion between the resin pattern and the electroless plating layer Is bad,
There is a problem that the electroless plating layer peels off.

Therefore, an object of the present invention is to improve the adhesion of the plating layer and provide a highly reliable method for manufacturing a circuit board.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the method for producing a circuit board of the present invention provides a double-sided copper-clad laminate with through holes to activate the copper foil on the laminate. A first circuit pattern is provided by patterning, an interlayer insulating resist layer is provided except for the through holes and the connecting portions, a metal powder-filled resin pattern is provided on the interlayer insulating resin layer, and the surface of the resist pattern is provided. Is characterized in that a circuit pattern is provided by roughening and performing chemical copper plating.

The metal powder-containing resist pattern can be obtained by predrying a circuit-forming resist layer made of a photosensitive resin composition containing a metal powder and an acid-soluble filler, exposing it in a pattern, and developing it. .

The photosensitive resin composition may further contain a prepolymer of diallyl phthalate, a polyfunctional unsaturated compound, a photopolymerization initiator, an epoxy resin, dicyandiamide, and a diaminotriazine modified imidazole.

The metal powder may be at least one selected from copper, nickel, iron and alloy powders thereof, and the metal may be replaced with a noble metal after the surface roughening.

Materials and the like that can be used in the present invention will be described below.

The photosensitive resin composition (resist for forming a circuit) that can be used in the present invention comprises a prepolymer of diallyl ester of ortho, iso or terephthalic acid. Such prepolymers are also called β-polymers, for example
“Diallyl phthalate resin” by Naomi Yoshimi, published by Nikkan Kogyo Shimbun Co., Ltd. (Sho 44), describes its detailed properties and production method. The above-mentioned prepolymer can also be obtained from Osaka Soda kk, for example.

The prepolymer preferably has a molecular weight of about 3,000 to 30,000, but is not limited thereto.
Further, the description that the prepolymer is included does not prevent inclusion of a small amount of the diallyl phthalate monomer or the γ-polymer having a three-dimensional network structure, which remains or is formed with the synthesis of the prepolymer.

Furthermore, the circuit-forming resin composition that can be used in the present invention comprises a polyfunctional unsaturated compound having at least two ethylene bonds in the molecule. Such a compound can be obtained by, for example, an esterification reaction of an unsaturated carboxylic acid and a polyhydroxy compound having a valence of 2 or more. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, and the like. Examples of the dihydroxy or higher polyhydroxy compound include ethylene glycol, propylene glycol, triethylene glycol,
Examples thereof include hydroquinone and pyrogallol. Examples of the compound obtained by the esterification reaction of the unsaturated carboxylic acid and the polyhydroxy compound include diethylene glycol diacrylate, polyethylene glycol diacrylate, neopentyl glycol diacrylate, 1,
5 Pentanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, 1,3 butanediol dimethacrylate And the like, diacrylate and dimethacrylate compounds, and dipentaerythritol tri, tetra, penta, hexaacrylate or methacrylate, sorbitol tri, tetra, penta, hexaacrylate or methacrylate, and other polyvalent acrylates and methacrylates. Compounds, oligoester acrylate, oligoester methacrylate, etc., epoxy resin and acrylic acid and Examples thereof include an epoxy (meth) acrylate formed by the reaction of methacrylic acid. Among them, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol tri, tetra, penta, hexaacrylate and dipentaerythritol tri, tetra, penta, hexaacrylate are It is preferable because it cures faster.

The above examples do not limit the addition of monofunctional unsaturated compounds, and mixtures of polyfunctional unsaturated compounds can be used if necessary. The above compounds may be used alone or in combination of two or more.

Further, the circuit-forming resin composition that can be used in the present invention contains a photopolymerization initiator. The photopolymerization initiator is, for example, acetophenone, a derivative of acetophenone, benzophenone, a derivative of benzophenone, Michler's ketone, benzyl, benzoin, benzoin alkyl ether, benzyl alkyl ketal, thioxanthone, derivative of thioxanthone, anthraquinone, derivative of anthraquinone, tetramethylthiuram. Monosulfide, 1-hydroxycyclohexyl phenyl ketone,
2-Methyl-1- [4- (methylthio) phenyl] -2
Examples include α-aminoketone compounds represented by morpholino-propene-1. Among them, benzoin alkyl ether, thioxanthone derivative, 2-methyl-
An α-aminoketone compound typified by 1- [4- (methylthio) phenyl] -2-morpholino-propene-1 is preferable because of rapid curing, and 2-methyl-1- [4-
(Methylthio) phenyl] -2-morpholino-propene-1 is more preferable because it cures quickly and has good storage stability.

The photopolymerization initiators may be used alone or in combination of two or more. Further, it is possible to use together an amine compound that sensitizes the action of the photopolymerization initiator.

Furthermore, the circuit-forming resin composition that can be used in the present invention contains an appropriate amount of an epoxy resin and a curing agent in order to prevent the solder resist on the copper foil from peeling off in an alkaline plating solution.

The epoxy resin has, on average, two or more epoxy groups per molecule, and examples thereof include polyphenols such as bisphenol A, halogenated bisphenol A, catechol, and resorseal, or polyhydric compounds such as glycerin. Polyglycidyl ether obtained by reacting alcohol with epichlorohydrin in the presence of a basic catalyst, or polyglycidyl ester, epoxy novolak obtained by condensing novolac type phenolic resin with epichlorfedrin, epoxy by a peroxidation method Examples thereof include epoxidized polyolefin, epoxidized polybutadiene, dicyclopentadiene oxide, and epoxidized vegetable oil.

Further, as the curing agent, a mixture of a diaminotriazine-modified imidazole compound and dicyandiamide is suitable for preventing peeling of the solder resist.

As the above-mentioned diaminotriazine-modified imidazole compound that can be used in the present invention, a compound having a latent curability with respect to an epoxide compound represented by the following general formula can be used.

For example, 2,4-diamino-6 {2'-methylimidazole- (1 ')} ethyl-S-triazine, 2,4-diamino-6 {2'-ethyl-4'-methylimidazole-
(1 ′)} Ethyl-S-triazine, 2,4-diamino-
6 {2'-undecylimidazole- (1 ')} ethyl-S-triazine or 2,4-diamino-6 {2'-
Methyl imidazole (1 ')} ethyl-S-triazine, an isocyanuric acid addition product, etc. are mentioned. Among them, 2,4 diamino-6 {2'-methylimidazole (1 ')} ethyl-S-triazine and its isocyanuric acid adduct are preferable from the viewpoint of curing rate, and 2,4 diamino-6- {2' -Methylimidazole (1 ')} ethyl-
More preferred is S-triazine.

Furthermore, the circuit-forming resin composition that can be used in the present invention comprises a metal powder. As the metal powder, copper,
Inexpensive metal powders such as nickel and iron, and alloy powders of these metals can be used. The above metal powders may be used alone or in combination of two or more. Further, a resin powder coated with the above metal and a metal powder coated with another metal can also be used. The particle size of the metal powder is preferably about 0.5 to 10 μm.

Furthermore, the resist composition for forming a circuit that can be used in the present invention is
It comprises an acid-soluble filler. Examples of the acid-soluble powder include (heavy and light) calcium carbonate, talc and the like. Further, a rubber-modified resin that is soluble in a strong acid can also be used. Of these, heavy and light calcium carbonates are preferable because they can be dissolved by simply immersing them in an acid and the process is simple.

Furthermore, the circuit-forming resin composition used in the present invention may contain an organic solvent as a diluent, an antifoaming agent, a filler, and a thixotropic agent, if necessary.

Suitable examples of the organic solvent include high-boiling solvents such as cellosolve, cellosolve acetate, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, terbineol, cellosolve acetate, butyl cellosolve acetate, and among them, cellosolve acetate. Butyl cellosolve acetate is more preferable because its viscosity can be easily adjusted and it is particularly suitable for printing. However, acetone, methyl ethyl ketone,
It does not mean that low boiling solvents such as ethanol cannot be used.

As the defoaming agent, an organosilicon compound containing a siloxane bond, typified by silicone oil, is preferably used.

The filler is added as an inorganic filler to the resist composition, and fine powder of silica, alumina, talc, or the like is preferably used.

As the thixotropic agent, ultrafine silica powder is preferably used because it contributes to the improvement of the viscosity of the resin composition, especially the thixotropy.

The mixing ratio of the circuit-forming resist used in the present invention is 100 parts by weight of the diallyl phthalate resin, 1 to 30 parts by weight of the polyfunctional unsaturated compound, 0.5 to 20 parts of the photopolymerization initiator.
Parts by weight, 5 to 30 parts by weight of the epoxy resin, 10 to 200 parts by weight of the metal powder (0.5 to 10 μm), 30 to 100 parts by weight of the acid-soluble filler (1 to 30 μm), and a diaminotriazine-modified imidazole. The compounding ratio of the compound is 1 to 20 parts by weight with respect to 100 parts by weight of the epoxy resin, and the compounding ratio of dicyandiamide is 0.5 to 15 parts by weight with respect to 100 parts by weight of the epoxy resin.

When the compounding ratio of each component of the above resin composition for forming a circuit is less than the lower limit thereof, the photosensitive sensitivity of the resin and the adhesiveness with the electroless plating layer are insufficient, which is a problem in practical use. This is a practical problem because the exposure property, plating resistance, and heat resistance deteriorate.

In addition, the additives are related to the screen printability, and are adjusted by adding an appropriate amount.

The circuit-forming resin composition used in the present invention can be applied by printing on the entire surface of the substrate by a general screen printing method. This coating film is dried to enable close contact with a negative mask, UV exposure is performed through the negative mask, and a circuit pattern is formed by solvent development. Next, this circuit pattern is thermally cured, and the filler is etched with an acid to roughen the surface. The surface-roughened circuit pattern can secure desired plating solution resistance.

A conductor path can be obtained by replacing the inexpensive metal on the exposed surface of the surface-roughened pattern with a noble metal such as palladium, gold, platinum or silver and then performing chemical copper plating.

Post-exposure and / or heat treatment may be added to the circuit-forming resin pattern, if necessary.

Further, the composition obtained by removing the metal powder from the composition for the circuit forming resin can be used as an interlayer insulating resin. A multilayer printed circuit board can be manufactured by performing the above manufacturing process on this interlayer insulating resin.

[Operation] In the present invention, the adhesion to the chemical copper plating layer is improved by roughening the surface of the circuit forming resin pattern. As a roughening means, for example, if a resin composition is mixed with an acid-soluble filler and immersed in hydrochloric acid or the like after curing of the resist, the filler is easily dissolved and the surface is roughened. . As a result, the bonding area between the resin and the plating layer is increased, and the adhesion between them is improved.

The resin composition for forming a circuit can be used as an interlayer insulating resin composition for a multilayer circuit by removing the metal powder from the composition.

In the above prior art, the photosensitive resin composition was expensive because a large amount of metal such as Pd was mixed, but as described above, the circuit-forming resin composition used in the present invention contains copper and nickel. If an inexpensive metal powder such as iron is mixed and the surface-exposed metal is replaced with a noble metal such as palladium after the surface roughening, the amount of the noble metal required can be reduced. it can.

Further, the above conventional manufacturing method mainly uses acrylonitrile butadiene rubber as a resin component, so even if the photosensitive resin composition layer is dried to volatilize the solvent, it is sticky, and therefore the mask However, there is also a problem that the photosensitive resin composition adheres to the mask and the pattern accuracy decreases, but the circuit-forming resin composition used in the present invention contains a large amount of diallyl phthalate resin which is normally solid. By including it in the composition, it can be used as a circuit-forming resin composition by adding a solvent, and can be easily applied to a substrate or the like by a screen printing method. After application, the circuit-forming resin composition is solidified by preliminary drying, and even if the negative mask is brought into close contact with the circuit-forming resin and exposed, it does not become sticky. Further, this circuit-circuit forming resin resists a high temperature alkaline plating solution by adding an epoxy resin and a predetermined curing agent.

[Examples] Hereinafter, the method for manufacturing a circuit board of the present invention will be further described with reference to specific examples.

First, a glass-epoxy double-sided copper-clad laminate in which a copper foil 2-1 having a thickness of 35 μm as shown in FIG. 1 (a) is stretched on both sides of a substrate 1 is drilled through holes as shown in FIG. 1 (b). No. 4 is provided and the copper foil is soaked in a Sn / Pd catalyst solution for activation.
The activation catalyst 3 was attached to the surface of 2 and the wall surface of the through hole 4. This activation is for enabling chemical copper plating on the wall surface of the through hole, and the activation catalyst 3 may be attached to at least the wall surface of the through hole. Then, a dry film, which is a kind of resin, is laminated on the substrate by a conventional method, and a land and circuit pattern 2-3 is formed by a tenting method including the steps of exposure, development, etching and peeling, as shown in FIG. 1 (c). Was formed.

Then, as shown in FIG. 1 (d), an interlayer insulating resist 5 formed by removing the metal powder from the circuit-forming resin composition composition is applied to the entire surface by screen printing,
Preliminary drying was performed at 80 ° C. for 30 minutes to solidify the surface of the resin composition, so that the negative mask could be in close contact. The following was used as the interlayer insulating resin composition 5.

Interlayer insulation resin composition composition (a) diallyl phthalate resin …… 65g (average molecular weight 7,000, Isodap, manufactured by Osaka Soda KK) (b) trimethylolpropane trimethacrylate ……
2.6g (c) Epoxy resin ...... 10g (Epicoat 828, epibis type epoxy resin, manufactured by Yuka Shell Epoxy KK) (d) 2-methyl-1 [4- (methyl) phenyl] -2
-Morpholino-propane-1 ...... 1.3 g (f) dicyandiamide ...... 0.7 g (f) 2,4-diamino-6 [2'-methylimidazole- (1 ')] ethyl-S-triazine 0.25 g ( G) Calcium carbonate …… 30g (Special heavy-duty carbon, average particle size 20μm, Takehara Kagaku KK) (H) Silicon ultrafine powder Aerosil RY-200 …… 0.5g (Nippon Aerosil KK) (Re) Silicone oil SH-203 …… 1.5g (nu) Ethylene glycol monobutyl ether …… 44g Mix the above components (a) to (d) and (nu) and mix at about 80 ℃.
The mixture was heated and stirred for 30 minutes. Next, an appropriate amount of the above (e) to (i) was added to this heated and stirred mixture and kneaded with a three-roll to obtain a photosensitive interlayer insulating resin composition.

Then, a negative mask is brought into close contact with the pre-dried resin composition layer, exposed to ultraviolet rays for 0.5 to 2 minutes using a 400 W high-pressure mercury lamp, and exposed by spray development using 1,1,1-trichloroethane. did. Next, it was immersed in 10% hydrochloric acid for 2 minutes to roughen the surface, and then heat-cured at 150 ° C. for 30 minutes to form an insulating resin layer 5 (FIG. 1 (d)).

Next, a circuit-forming resin composition obtained by mixing the interlayer insulating resin composition with a metal powder is solid-printed on the insulating resin layer 5 with a 180-mesh stainless screen to about 80 ° C.
It was pre-dried for 30 minutes. After the preliminary drying, the surface of the resin composition was solidified so that the negative mask could be adhered thereto. The following were used as the resin composition for circuit formation.

Circuit forming resin composition (l) Interlayer insulating resin composition ...... 150g (e) Ni powder ...... 50g (average particle size 0.5μm, manufactured by Mitsui Mining & Smelting Co., Ltd.) The above component (l) was synthesized in the same manner as above. The component (e) was sufficiently kneaded to obtain a photosensitive circuit-forming resin composition. Then, similarly to the above, the resin composition layer for circuit formation is exposed,
Chlorocene development, surface roughening treatment with acid, and heat curing were performed to form a circuit forming resin pattern 6 (FIG. 1 (e)).

The substrate on which the surface-roughened resin pattern 6 is formed (first
Figure (e)) was immersed in an aqueous solution of palladium chloride at 60 ° C for 30 seconds to replace the resin pattern portion 6 with palladium (not shown).

Next, the resin pattern 6 was immersed in a chemical copper plating solution (manufactured by Shipley Co., Ltd.) having the following composition for 20 minutes to perform thin chemical copper plating on the resin pattern 6 to a thickness of about 0.4 μm.

Thin chemical copper plating solution Copper mix 328A …… 125 ml Copper mix 328L …… 125 ml Copper mix 328C …… 25 ml Distilled water …… Amount to make the total amount 11 Then, using the chemical copper plating solution of the following composition, the following conditions Then, thick chemical copper plating was performed to form a circuit pattern 7 shown in FIG. 1 (f).

Thick copper plating solution CuSO ₄ −5H ₂ O …… 12g EDTA ・ 2Na …… 42g NaOH …… 12g Polyethylene glycol stearylamine …… 0.1g α, α′-dipyridyl …… 5mg 37% Formalin …… 5mg Na ₂ SiO ₃・ 9H ₂ O …… 1g Distilled water …… Total amount is 11 Plating condition Plating solution temperature …… 70 ℃ pH …… 12.3 hours …… 20 hours The plating solution composition in the plating tank is kept constant by automatic control. did.

As a result of evaluating the adhesiveness between the interlayer insulating resin pattern 5 and the circuit forming resist pattern 6 and the circuit pattern 7 of the circuit board manufactured as described above, the peel strength is 1 Kg / cm or more and the adhesiveness is good. I found out. Furthermore, it was also found that even if the resin pattern was immersed in a solder bath at 260 ° C. for 10 seconds, the resin pattern did not deteriorate such as swelling and peeling, and had good solder heat resistance.

[Effect of the Invention] As described above, according to the present invention, the adhesion between the resin pattern and the electroless plating is remarkably improved, so that the electroless layer is not peeled off and the reliability is improved. Further, by mixing an inexpensive metal into the resin and then replacing the metal only on the surface of the resin with the noble metal, the manufacturing cost of the circuit board can be reduced. Furthermore, by selecting the resin composition as described above, stickiness of the resin composition can be prevented and the resin pattern accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the manufacturing method of the present invention. 1 ... Glass epoxy substrate, 2-1,2-2 ... Copper foil, 3
...... Activating catalyst, 4 ... Through holes, 5 ... Interlayer insulating resin layer, 6 ... Circuit forming resin and pattern, 7 ... Electroless copper plating.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor, Osamu Oka, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture, Ltd., Production Engineering Laboratory, Hitachi, Ltd. (72) Inventor, Shusaku Izumi, 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa (56) References JP-A-53-76367 (JP, A) JP-A-60-110877 (JP, A)

Claims (4)

[Claims] 1. A double-sided copper-clad laminate is provided with a through-hole, an activation catalyst is attached to at least the wall surface of the through-hole, and the copper foil on the laminate is patterned to provide a first circuit pattern, An interlayer insulating resin layer is provided except for the through hole portion and the connecting portion, and a circuit forming resin layer made of a photosensitive resin composition containing a metal powder and an acid-soluble filler is formed on the interlayer insulating resin layer. Then, the circuit-forming resin layer is pre-dried, exposed in a pattern, and developed to provide a metal powder-filled resin pattern, the surface of the resin pattern is roughened, and chemical copper plating is performed to form a second pattern. A method for manufacturing a circuit board, characterized in that the circuit pattern is provided. 2. The photosensitive resin composition further comprises a prepolymer of diallyl phthalate, a polyfunctional unsaturated compound, a photopolymerization initiator, an epoxy resin, dicyandiamide, and a diaminotriazine-modified imidazole. 2. A method for manufacturing a circuit board according to claim 1. 3. The method for manufacturing a circuit board according to claim 1, wherein the roughening of the surface of the resin pattern is performed by immersing the resin pattern in an acid. 4. A double-sided copper-clad laminate is provided with a through hole, an activation catalyst is attached to at least the wall surface of the through hole, and the copper foil on the laminate is patterned to provide a first circuit pattern, An interlayer insulating resin layer is provided except for the through hole portion and the connecting portion, and a metal powder-containing resin pattern containing at least one selected from copper, nickel, iron and alloy powders thereof is provided on the interlayer insulating resin layer. The surface of the resin pattern is roughened, the metal powder exposed on the surface of the metal powder-containing resin pattern is replaced with a noble metal, and the surface of the metal powder-containing resin pattern after the replacement is subjected to chemical copper plating. 2. A method for manufacturing a circuit board, characterized in that the circuit pattern 2 is provided.