JPH10209645A - Manufacture of multilayer printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a multilayer printed board having excellent adhesion, surface smoothness and other printed board performances, without volatilization of a solvent. SOLUTION: The manufacturing method comprises: (a) a step of coating the surface of a board, where a conductive circuit is formed, with powder coating material and baking the board to form an insulating coating film layer; (2) a step of forming a hole, which reaches the surface of the circuit under the insulating coating film layer, in the insulating coating film layer by laser; (3) a step of roughening the surface of the board having the hole, then copper- plating the surface to form a copper plating layer on the insulating coating film layer, such that the copper plating layer is electrically connected to the circuit under the insulating coating film layer via the copper plating formed in the hole; and (4) a step of processing the copper plating layer on the insulating coating film layer and forming a conductive circuit. The steps (1) to (4) are repeated for the surface of the board where the conductive circuit is formed at the step (4), in accordance with necessity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed circuit board using an insulating coating layer formed by a powder coating.

[0002]

2. Description of the Related Art Conventionally, a multilayer printed circuit board is formed by applying a resin solution on a substrate on which a conductive circuit is formed, forming a dried insulating resin layer or an insulating resin layer obtained by press-bonding an insulating film, and performing laser processing. It is manufactured by drilling holes by a photographic method or the like, roughening the surface of the insulating layer, copper plating, forming a circuit on the copper plating layer, and repeating the above steps as necessary.

[0003] However, when an insulating resin layer is formed by coating and drying a resin solution, the solvent evaporates from the resin solution layer during drying and the smoothness of the surface of the formed insulating resin layer is impaired, and the copper plating layer is formed. There is a problem that it adversely affects the formation of water and causes air pollution due to evaporation of the solvent.

In the case where an insulating resin layer is formed by pressing an insulating film by pressure, there is a problem that adhesion to the substrate is poor due to poor followability to the substrate.

According to the present invention, an insulating resin layer having good adhesion to a substrate and a copper plating layer and having good surface smoothness can be formed without volatilization of a solvent, thereby providing a multilayer print having excellent performance. The purpose is to obtain a substrate.

[0006]

The inventors of the present invention have conducted intensive studies and have found that the above object can be achieved by coating and baking a powder coating to form an insulating resin layer, thereby completing the present invention. Reached.

That is, according to the present invention, there is provided (1) a step of coating and baking a powder coating on a substrate surface on which a conductive circuit is formed to form an insulating coating layer, and (2) insulating the insulating coating layer by laser. A step of performing a drilling process to reach a circuit surface under the coating layer, (3) copper plating is performed after roughening the surface of the substrate subjected to the drilling, and a copper plating layer is formed on the insulating coating layer; Making the copper plating layer and the circuit under the insulating coating layer conductive through the copper plating formed in the drilled portion; and (4) forming a conductive circuit by processing the copper plating layer on the insulating coating layer. Is performed, and if necessary, the steps (1), (2), (3) and (4) are performed on the surface of the substrate on which the conductive circuit is formed on the insulating coating layer formed in the step (4). Providing a method of manufacturing a multilayer printed circuit board characterized by repeatedly performing It is.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a substrate on which a conductive circuit is formed in the present invention, for example, a substrate on which a conductive film is formed by processing a conductive film of a substrate having a conductive film formed thereon, and the like Can be mentioned.

As the substrate having a conductive film formed on the surface, for example, a plastic plate such as an electrically insulating glass-epoxy plate or a plastic film or the like may be used.
Copper, a conductive film laminated substrate obtained by a method of bonding a metal foil such as aluminum, or a method of plating a metal such as copper; the conductive film laminated substrate, a through hole is provided on the inner surface of the through hole, for example, Examples of the substrate include a substrate in which the inner surface of the through hole is made conductive by a method of forming a plating layer by copper plating or the like.

As a method of forming a conductive circuit by processing a substrate having a conductive film formed on the surface, for example, a photosensitive etching resist is formed on a substrate having a conductive film formed on the surface. Exposure and development are performed in a pattern, then the conductive film is etched, and the remaining resist is removed, for example, by a known lithographic method.

In the method of the present invention, a powder coating is applied and baked on the surface of the substrate on which the conductive circuit is formed, as a step (1), to form an insulating coating layer. The surface of the substrate on which the conductive circuit has been formed may be one in which the surface of a conductive film such as copper is roughened by previously performing a blackening treatment for oxidizing and blackening the copper surface. The blackening treatment can be performed using an alkali treating agent such as caustic soda.

In the powder coating applied in the step (1), as an insulating coating layer to be formed, electrical insulation, dimensional stability, mechanical strength of the coating, surface smoothness, adhesion to the substrate surface It can be used without any particular limitation as long as it is excellent in performance required by an insulating coating layer such as properties, and examples thereof include an acrylic resin type, an epoxy resin type, a polyester resin type, a polyamide resin type, and a urethane resin type. It is possible,
Among them, epoxy resin is preferred.

The epoxy resin-based powder coating material has a number average molecular weight of 400 to 6000, preferably 1,000 to 4,000.
Preferably, the base resin is an aromatic epoxy resin having 000. Commercially available aromatic epoxy resins include, for example, Epicoat 1001, 1002, and 10
Bisphenol-type epoxy resins such as 04, 1007, 1009, and 1010 (all of which are manufactured by Yuka Shell Epoxy); phenol novolak-type epoxy resins such as Epicoat 154 (manufactured by Yuka Shell Epoxy);
Cresol novolak type epoxy resin such as Epicoat 190S80 (manufactured by Yuka Shell Epoxy) can be used. The epoxy resin-based powder coating may be composed of only a base resin, but if necessary, a coating such as a curing agent, a curing catalyst, a pigment, organic resin fine particles, a flame retardant, a coating surface adjusting agent, etc. may be added. Agents can be included.

As the curing agent, ethylenediamine,
Polyamine compounds such as diethylenetriamine, triethylenetetramine, aminoethylpiperazine, imidazole, m-phenylenediamine, 4,4'-diaminodiphenylmethane, metaxylylenediamine, benzyldimethylamine; reaction products of polycarboxylic acid and diamine, dicyandiamide Polyamide compounds such as phthalic anhydride, hexahydrophthalic anhydride, pyromellitic anhydride, and chlorendic anhydride; isophorone diisocyanate, metaphenylene diisocyanate, tolylene diisocyanate, and xylylene diamine. Isocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, burette or isocyanurate of these isocyanate compounds Compounds having a plurality of isocyanate groups, such as adducts or adducts of these isocyanate compounds with polyhydric alcohols, low molecular weight polyester resins or water, are blocked with a blocking agent such as oxime, phenol or alcohol. Blocked polyisocyanate compounds; and amino resins such as methylolated urea resins, methylolated melamine resins, and methylolated benzoguanamine resins, in which the methylol group may be etherified with a monoalcohol having 1 to 6 carbon atoms. .

The curing catalyst is used for accelerating a reaction between an epoxy resin and a curing agent.
What is necessary is just to select and use suitably according to the kind of hardener, etc. For example, when the curing agent is a blocked polyisocyanate compound, dibutyltin oxide, dioctyltin oxide, dibutyltin dioctate, dibutyltin dilaurate, dioctyltin dioctate, dioctyltin dilaurate, dibutyltin bis (acetylacetonate), dibenzyl Tin di (2-ethylhexylate), 2
-Lead ethylhexanoate, bismuth nitrate, zirconium naphthenate and the like. When the curing agent is an amino resin, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, neutralized products of basic compounds such as amine compounds of these sulfonic acids, phosphoric acid, etc. Can be mentioned.

Examples of the above-mentioned pigments include coloring pigments and extender pigments. By using talc, calcium carbonate, silica, alumina, etc. as a pigment, the surface of the formed insulating coating layer is roughened to improve the adhesion with the next insulating coating layer formed thereon. In this case, the roughening process can be performed smoothly.

Examples of the organic resin fine particles include rubber fine particles.
As described above, the surface roughening treatment of the insulating coating layer can be smoothly performed.

The flame retardant is used for imparting flame retardancy to the insulating coating layer, and examples thereof include antimony trioxide, a brominated epoxy resin, and red phosphorus.

Examples of the method of applying the powder coating on the substrate surface include a spray coating method and a fluid immersion method. The coating film thickness may be any film thickness capable of exhibiting electrical insulation. The coating thickness is preferably such that an insulating coating layer having a thickness in the range of 10 to 100 μm is formed. The baking conditions for the coated powder coating layer may be set as appropriate according to the type of powder coating or the like.
Is preferably in the range of 30 to 180 minutes.

After the insulating coating layer is formed in the above step (1), in the step (2), a hole is formed in the insulating coating layer by a laser to reach a circuit surface below the insulating coating layer by a laser. Excimer lasers, carbon dioxide lasers, and the like can be given as lasers used for drilling.

After the step (2), in the step (3), copper plating is performed on the surface of the insulating coating layer. Before the copper plating, the adhesion of the copper plating layer to be formed is improved.
It is necessary to finely roughen the surface of the insulating coating layer (including the surface of the through hole) by the roughening treatment. This roughening treatment can be performed using an oxidizing agent-containing alkaline treating agent such as a permanganic acid / narium hydroxide-based treating agent.

After performing the above roughening treatment, copper plating is performed on the surface of the substrate having the perforated insulating coating layer.
As a result, a copper plating layer is formed on the insulating coating layer and on the perforated portion. By forming the copper plating layer in the drilled portion, the copper plating layer on the insulating coating layer and the circuit under the insulating coating layer are connected to each other and can be conducted. Copper plating can be performed by electroless plating, electrolytic plating, or the like.

Further, after step (3), in step (4), the copper plating layer on the insulating coating layer of the substrate is processed to form a conductive circuit. Processing of the copper plating layer for forming the conductive circuit is performed by forming a photosensitive etching resist on the copper plating layer, performing pattern exposure and development on the resist by a lithographic method, and then etching the copper plating layer and removing the remaining resist. The removal can be performed by a method known per se, such as a method of performing removal.

The photosensitive etching resist may be any etching resist that can be used for forming a printed circuit board, and may be any of a liquid resist and a dry film resist, and may be any of a negative photoresist and a positive photoresist. Can also be used.

In the present invention, the above steps (1) to (4)
By performing one cycle of the processing having the above, the insulating coating layer and the circuit can each be increased by one layer. In the present invention, the number of insulating coating layers and the number of circuit layers are not particularly limited, and the number of steps (1) to (1) is determined according to the required number of layers.
The processing having (4) can be repeated the required number of cycles. By increasing the number of layers of the multilayer printed board, it is possible to achieve both high density and miniaturization of the circuit.

[0026]

The present invention will be described more specifically with reference to the following examples.

Example 1 A circuit board in which a copper circuit having a thickness of 18 μm was formed on a glass-epoxy board having a size of 340 × 510 mm,
"Evaclad No. 3800" (Kansai Paint Co., Ltd.)
And an epoxy resin-based powder coating and an extender pigment) were electrostatically coated with a target of a dry film thickness of 50 μm and baked at 180 ° C. for 60 minutes to form an insulating coating layer. The dry thickness distribution of this insulating coating layer was 50 ± 5 μm.

Next, a carbon dioxide laser "GS500H"
Laser drilling is performed on the insulating coating layer using (manufactured by Sumitomo Heavy Industries, Ltd.), and a columnar hole having a diameter of 0.15 mmφ reaching the copper circuit surface under the insulating coating layer is formed by 300 holes.
I opened 0 pieces. Next, after the surface of the insulating coating layer was roughened by a known method using a permanganic acid / sodium hydroxide-based processing solution, the surface of the insulating coating layer was neutralized with a hydrazine sulfate-based processing solution. Then, after attaching a palladium catalyst to the surface of the insulating coating layer, electroless copper plating was performed, and further electrolytic copper plating was performed to form a copper plating layer on the surface of the insulating coating layer including the perforated portion. . The thickness of the copper plating layer on the surface of the insulating coating layer was 25 μm. The copper plating layer on the surface of the insulating coating layer and the copper circuit on the circuit board are electrically connected through the copper plating layer formed in the drilled portion.

Further, a negative photosensitive resist is applied to the copper plating layer on the insulating coating layer surface obtained as described above, dried, and the surface is exposed and developed through a negative photomask. Etching was performed, and then a comb-type copper circuit having a space width of 318 μm was formed on the surface of the insulating coating layer by a lithographic method of removing the remaining resist, thereby obtaining a multilayer printed board having two layers of copper circuits.

Example 2 In Example 1, instead of a circuit board having a copper circuit having a thickness of 18 μm formed on a glass-epoxy substrate having a size of 340 × 510 mm, the two layers obtained in Example 1 were used. Was performed in the same manner except that a multilayer printed circuit board having a copper circuit was used to obtain a multilayer printed circuit board having a three-layer copper circuit.

Example 3 A circuit board formed by forming a copper circuit having a thickness of 35 μm on a glass-epoxy board having a size of 340 × 510 mm,
"Evaclad No. 9000" (Kansai Paint Co., Ltd.)
And an epoxy resin-based powder coating) was electrostatically coated with a target of a dry film thickness of 80 μm and baked at 180 ° C. for 60 minutes to form an insulating coating layer. The dry thickness distribution of this insulating coating layer was 8
It was 0 ± 9 μm.

Then, in the same manner as in Example 1, a hole was formed by laser, a copper plating layer was formed, and a copper circuit was formed on the surface of the insulating coating layer by a lithographic method to obtain a multilayer printed circuit board having two copper circuits. . Here, the thickness of the copper plating layer formed on the insulating coating layer was 25 μm.

Example 4 A circuit board in which a copper circuit having a thickness of 18 μm was formed on a glass-epoxy board having a size of 340 × 510 mm was prepared as follows.
"Evaclad No. 3850" (Kansai Paint Co., Ltd.)
Epoxy-polyester resin-based powder coating, containing an extender pigment), and electrostatically coating with a target of a dry film thickness of 60 μm.
For 90 minutes to form an insulating coating layer. The dry thickness distribution of this insulating coating layer was 60 ± 7 μm.

Then, in the same manner as in Example 1, drilling with a laser, formation of a copper plating layer, and formation of a copper circuit on the surface of the insulating coating layer by a lithographic method were performed to obtain a multilayer printed circuit board having two copper circuits. . Here, the thickness of the copper plating layer formed on the insulating coating layer was 30 μm.

Example 5 In Example 3, "Evaclad N" was used as the powder coating material.
o. 9000 instead of “Evaclad No. 90”
Example 2 except that a powder coating in which 20 parts by weight of “PNR-1H” (manufactured by Nippon Synthetic Rubber Co., Ltd., carboxylic acid-modified NBR resin fine particles) was uniformly mixed with 100 parts by weight of “00” was used.
Was performed in the same manner as in the above, to obtain a multilayer printed circuit board having a two-layer copper circuit.

In the multilayer printed circuit boards obtained in Examples 1 to 5, the copper plating layer formed on the insulating coating layer was excellent in uniformity of film thickness and adhesion to the insulating coating layer. When the following temperature cycle test and pressure cooker test were performed on these multilayer printed circuit boards, Examples 1 to
In any of the multilayer printed circuit boards of No. 5, no cracks were generated in the temperature cycle test, and the results were good. In the pressure cooker test, no change in the resistance value after the test was substantially recognized compared to before the test, and the results were good.

Test method Temperature cycle test: (−40 ° C. → 125 ° C. → −40 ° C.)
The step of performing the above temperature change over 30 minutes is defined as one cycle, and the above-mentioned temperature change is performed 1000 times on the multilayer printed board. The appearance of the multilayer printed circuit board after the test is visually evaluated.

Pressure cooker test: temperature 110
A multilayer printed circuit board is placed in a pressure oven at 85 ° C and 85% humidity for 30 minutes.
After performing a test of standing for 0 hour, take out and take out a space width of 318 μm in a comb-shaped copper circuit having a space width of 318 μm.
The resistance value between the copper layers of m is measured according to JISZ-3197 type 2 and is compared with the resistance value of the multilayer printed circuit board before the test.

[0039]

According to the present invention, since the insulating coating layer formed in the present invention is formed of a powder coating, there is no volatilization of the organic solvent at the time of forming the insulating coating layer, which is advantageous in working environment and global environment conservation. . The insulating coating layer has good adhesion to the substrate and the copper plating layer, and has excellent surface smoothness, so that copper plating with good uniformity can be easily formed. Therefore, the method of the present invention is advantageous in working environment and global environment preservation, and a multilayer printed board having excellent performance can be obtained by the method of the present invention.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideo Kogure 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Kansai Paint Co., Ltd.

Claims (4)

[Claims] 1. The method according to claim 1, further comprising the step of:
A step of coating and baking a powder coating to form an insulating coating layer; (2) a step of drilling the insulating coating layer by a laser to reach a circuit surface below the insulating coating layer; (3) a step of drilling After roughening the processed substrate surface, copper plating is performed,
Forming a copper plating layer on the insulating coating layer, and enabling conduction between the copper plating layer and a circuit under the insulating coating layer through copper plating formed in the drilled portion; and (4) an insulating coating film Processing the copper plating layer on the layer to form a conductive circuit, and, if necessary, on the surface of the substrate on which the conductive circuit has been formed on the insulating coating layer formed in the step (4).
A method for manufacturing a multilayer printed circuit board, wherein the steps (1), (2), (3) and (4) are repeated. 2. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein in performing the step (1), the surface of the substrate on which the conductive circuit is formed is subjected to a roughening treatment in advance. 3. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein the powder coating used in the step (1) uses an epoxy resin as a base resin. 4. The powder coating used in the step (1) contains at least one kind of fine particles selected from organic resin fine particles and an extender which are not melted at a heating temperature. Or a method for manufacturing a multilayer printed circuit board according to item 3.