JP2001135911A - Method of forming holes in copper clad board using carbon dioxide laser - Google Patents

Abstract

(57) [Summary] [Problem] To produce a surface-treated copper-clad board without dents and resin adhesion, and to use this copper-clad board to provide a small hole for a high-density printed wiring board with excellent reliability. Providing a method of forming SOLUTION: The copper foil subjected to the double-sided treatment is laminated and formed using a copper foil with a carrier to which at least a part of the periphery of the copper foil is adhered, and is preferably selected from 10 to 60 mJ / pulse from above the copper clad plate. A method of forming a through-hole and / or a via-hole by directly irradiating a carbon dioxide gas laser having a selected output to process and remove the outer layer and the inner layer copper foil. [Effect] A small diameter through hole and / or a blind via hole having excellent reliability can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for drilling holes in a copper clad board obtained by using at least a surface layer of a double-sided treated copper foil having a surface treated. More specifically, the present invention relates to a method of forming a hole in a copper-clad plate for forming a small-diameter through hole and / or a blind via hole by directly irradiating a carbon dioxide gas laser on a surface-treated copper foil surface. The holed copper clad board is suitable as a high-density copper clad board for printed wiring boards. Preferably, after drilling, the copper foil burrs around the hole are removed with a chemical solution, and at the same time, a part of the copper foil surface is etched two-dimensionally so that the remaining thickness of the copper foil is 2 to 7 μm. Printed wiring boards obtained using copper-clad boards made by copper plating have small-diameter holes and are mainly used as high-density small printed wiring boards for new semiconductor plastic packages and the like. .

[0002]

2. Description of the Related Art Hitherto, a high-density printed wiring board used for a semiconductor plastic package or the like has not used a surface-treated copper foil subjected to a surface treatment. Further, the through holes for the through holes are drilled. In recent years, the diameter of drills has become smaller and smaller, and the hole diameter has been reduced to 0.15 mmφ or less.When drilling such small holes, the drill diameter is small, so the drill bends, breaks, and the processing speed when drilling. It has disadvantages such as slowness, and has problems in productivity, reliability, and the like. In addition, a hole of the same size was made in advance by using a negative film on the front and back copper foils in a predetermined manner using a negative film. If a carbon dioxide laser is used to form a through hole that penetrates the front and back sides, the position of the inner layer copper foil and the position of the upper and lower holes are displaced, resulting in a defect such as poor connection. Furthermore, heat resistance, migration resistance, insulation after moisture absorption, and the like have become problems in printed wiring boards that have become increasingly dense in recent years.

[0003]

SUMMARY OF THE INVENTION The present invention is directed to a method for forming a hole for solving the above problems and for obtaining a printed wiring board having excellent connection reliability for small-diameter holes.

[0004]

According to the present invention, a double-sided copper foil is used for at least an outer layer, and is laminated and formed into a copper-clad board with a double-sided copper foil by irradiating a carbon dioxide gas laser with a small diameter. In this method, a copper-clad board obtained by using the method of the present invention is used as a printed wiring board to provide a small, lightweight, high-density printed wiring board.

[0005] As a method of making a hole when a printed wiring board is produced, a through-hole and / or a blind via hole can be made by irradiating a carbon dioxide gas laser directly onto an outer layer copper foil which has been subjected to metal treatment or alloy treatment. It is possible to efficiently create a small-diameter hole at high speed. As the output of the carbon dioxide laser, a carbon dioxide laser preferably having an energy selected from 5 to 60 mJ / pulse is irradiated directly from above the copper foil to form through holes and / or blind via holes. After processing, burrs of the copper foil may occur in the holes. The burrs can be removed by mechanical polishing. However, from the viewpoint of dimensional change and the like, etching treatment with a chemical solution is preferable. After drilling holes, a chemical solution is sprayed to etch away a part of the surface copper foil and also remove the copper foil burrs by etching.

A circuit is formed on the front and back sides using a double-sided copper-clad board obtained by plating up this with copper plating, and a printed wiring board is formed by a standard method. In order to make the circuit on the front and back fine, it is preferable that the copper foil on the front and back layers be 2 to 7 μm. In this case, there is no occurrence of defects such as short-circuits and cut patterns, and a high-density printed wiring board is created. can do.
Further, the processing speed is remarkably faster than the case of drilling, the productivity is good, and the economy is excellent. Further, by using a polyfunctional cyanate ester, a thermosetting resin composition containing the cyanate ester prepolymer as an essential component as a tree insulating layer of a copper clad board, heat resistance, migration resistance, and after moisture absorption. A product excellent in heat resistance and the like was obtained. By adding the insulating inorganic filler, the homogeneity of the through hole and / or the blind via hole by the carbon dioxide laser is improved, and the connection reliability of the copper plated hole is improved.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a copper-clad board using a double-sided copper foil, and irradiates a carbon dioxide gas laser from above the copper-clad board with pulse oscillation to open through holes and / or blind via holes. . After drilling, burrs may be generated on the front and back surfaces and the inner layer copper foil. In this case, an etching solution is sprayed at a high pressure or sucked through the hole to dissolve and remove burrs on the inner and outer layer copper foils. After that, the whole is copper-plated by a standard method, and a circuit is formed to form a printed wiring board.

[0008] The double-sided copper foil required for preparing the copper clad board used in the present invention includes generally known copper foils. Preferably, the surface is treated with nickel metal or a nickel alloy or the like. Copper foil is used. As the surface treatment of the copper foil, at least on the outer surface of the outer layer copper foil irradiated with a carbon dioxide laser, one or more metals or alloys such as nickel, zinc, chromium, tungsten, cobalt, iron, etc. A known copper foil surface treatment is used. Preferably, a treatment containing nickel is used. The copper foil surface may be smooth or uneven. As a processing method, a generally known method is applied. For example, after roughening treatment by attaching the metal particles on the raw foil,
A thin copper plating is applied, and a treatment for forming the above-mentioned metal layer or alloy layer is further performed thereon, and a rust-proofing treatment is performed thereon, and then a copper foil processing or the like is used. After such treatment is performed on both sides of the copper foil, this copper foil is arranged on one side or both sides of the protective metal plate, and at least a part of the side end is adhered to the metal plate with an adhesive or the like, so that the protective metal plate is To obtain a copper foil with a double-sided treated copper foil on one or both sides. As the metal plate, aluminum, iron, other metal plates or alloy plates can be used. Preferably, an aluminum plate is used. The thickness is not particularly limited, but when used in place of a stainless steel plate during lamination molding, the thickness is 200 to 50.
It is preferably 0 μm. Metal sheets with double-sided copper foil on one side are placed on the outermost side with the double-sided copper foil facing the prepreg side during lamination molding, with double-sided copper foil attached to both sides of the metal plate Put this inside,
A plurality of these are combined, placed between hot plates, and laminated and formed under heat and pressure, preferably under vacuum. In general lamination molding, a stainless steel plate is used at the time of lamination molding. The thickness of the stainless steel plate is 1 to 2 mm, and the number to be inserted between hot plates is limited. In addition, dust and the like are mixed when the copper foil is placed on both sides of the prepreg, which causes dents, resin adhesion, and the like. However, when the copper foil with a metal plate of the present invention is used, there is almost no mixing of dust and the like, and since a metal plate having a thickness of 200 to 500 μm is used, compared to using a stainless steel plate between hot plates. A copper foil suitable for use in the present invention, which can contain a large number of sheets and is also excellent in productivity, is preferably used as an outer layer plate, in which both sides of an electrolytic copper foil having a thickness of preferably 3 to 12 μm are treated. used. As the inner layer plate, one having a thickness of 12 to 35 μm is suitably used. Regarding the alloy treatment, the alloy treatment with nickel is preferable from the viewpoint of the hole-forming property of the carbon dioxide laser. This double-sided copper foil, if used as it is, has a high possibility of surface contamination,
Generally, it is laminated and formed on a double-sided treated copper foil using a protective film such as a protective film or a metal plate. The film or the metal plate for the carrier for preventing surface contamination of the copper foil is not particularly limited, but aluminum having a thickness of 200 to 500 μm is preferably used. It is preferable that the protective sheet is used by bonding a part of the periphery to a double-sided treated copper foil for workability, prevention of scratches, and prevention of foreign matter such as dust. A thick aluminum plate can be used instead of a conventional stainless steel plate when laminating and forming, compared to using a stainless steel plate, a large number of sheets can be laminated and formed at the same time, and then when mechanical drilling is performed By drilling from above with the aluminum plate attached, the price is low. Also, when drilling with a carbon dioxide laser,
After peeling before drilling, laser can be directly irradiated on the copper foil to drill.

The copper clad board used in the present invention has at least one
It is a copper-clad board or a multilayer board having more than one copper layer, and may be a board-reinforced board, a film board, or a resin alone without a reinforcing board. However, from the viewpoint of dimensional shrinkage and the like, a glass cloth-based copper-clad plate is preferred. or,
When creating a high-density circuit, a thin copper foil on the surface layer can be used from the beginning, but preferably, a thick copper foil of 9 to 12 μm is laminated and formed, and after drilling with a carbon dioxide gas laser. A copper foil having a surface layer thinned to 2 to 7 μm with an etching solution is used.

The double-sided treated foil with a metal plate carrier of the present invention can be laminated and formed without using a stainless steel plate by setting a plurality of sheets at the time of laminating and forming (FIG. 1). Above and below the outermost layers, a part of the double-sided copper foil is adhered to one side of the metal plate carrier, the copper foil is placed on the prepreg side, and one side of the double-sided copper foil is placed on both sides of the metal plate inside. A stainless steel plate and a cushion are placed on the outermost side and placed between hot plates, and laminated under heat, pressure, or preferably under vacuum. Of course, it is also possible to use a stainless steel plate as a normal setup method and alternately arrange copper foils and prepregs to form a laminate.

As the base material of the copper clad board, generally known organic and inorganic woven fabrics and nonwoven fabrics can be used. Specifically, examples of the inorganic fibers include fibers such as E, S, D, and M glass. Examples of the organic fibers include wholly aromatic polyamide, liquid crystal polyester, and polybenzazole. These may be mixed. Films such as a polyimide film can also be used.

As the resin of the thermosetting resin composition of the copper clad board used in the present invention, generally known thermosetting resins are used. Specifically, an epoxy resin, a polyfunctional cyanate ester resin, a polyfunctional maleimide-cyanate ester resin, a polyfunctional maleimide resin, an unsaturated group-containing polyphenylene ether resin, and the like, and one or more kinds Are used in combination. From the viewpoint of through-hole shape in processing by high-output carbon dioxide laser irradiation, a thermosetting resin composition having a glass transition temperature of 150 ° C or higher is preferable, and has moisture resistance, migration resistance, and electrical characteristics after moisture absorption. In view of the above, a polyfunctional cyanate resin composition is preferred.

The polyfunctional cyanate compound which is a preferred thermosetting resin component of the present invention is a compound having two or more cyanato groups in a molecule. Specific examples include 1,3- or 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-, 1,4-, 1,6-, 1,8-, 2 , 6- or 2,7-
Dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4-dicyanatobiphenyl, bis (4-dicyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, 2,2- Bis (3,5-dibromo-4-cyanatophenyl) propane, bis (4-cyanatophenyl) ether, bis (4-cyanatophenyl) thioether, bis (4-cyanatophenyl) sulfone, tris (4-cy (Anatophenyl) phosphite, tris (4-cyanatophenyl) phosphate, and cyanates obtained by reacting novolak with cyanogen halide.

In addition to these, Japanese Patent Publication Nos. 41-1928 and 43-1846
8, polyfunctional cyanate compounds described in JP-A-44-4791, JP-A-45-11712, JP-A-46-41112, JP-A-47-26853 and JP-A-51-63149 can also be used. Further, a prepolymer having a molecular weight of 400 to 6,000 and having a triazine ring formed by trimerization of a cyanato group of these polyfunctional cyanate compounds is used. This prepolymer is obtained by polymerizing the above-mentioned polyfunctional cyanate ester monomer with a catalyst such as an acid such as a mineral acid or a Lewis acid; a base such as a tertiary amine such as sodium alcoholate; or a salt such as sodium carbonate. It can be obtained by: The prepolymer also contains some unreacted monomers and is in the form of a mixture of the monomer and the prepolymer, and such a raw material is suitably used for the purpose of the present invention. Generally, it is used after being dissolved in a soluble organic solvent.

As the epoxy resin, a generally known epoxy resin can be used. Specifically, liquid or solid bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin, butadiene, pentadiene, vinylcyclohexene, dicyclopentyl ether, etc. And polyglycidyl compounds obtained by reacting a polyol, a hydroxyl-containing silicone resin with an epohalohydrin, and the like. These may be used alone or in combination of two or more.

As the polyimide resin, generally known ones can be used. Specific examples include a reaction product of a polyfunctional maleimide and a polyamine, and a polyimide having a terminal triple bond described in JP-B-57-005406. These thermosetting resins may be used alone, but it is preferable to use them in an appropriate combination in consideration of the balance of properties.

Various additives can be added to the thermosetting resin composition of the present invention, if desired, as long as the inherent properties of the composition are not impaired. These additives include polymerizable double bond-containing monomers such as unsaturated polyesters and prepolymers thereof; polybutadiene, epoxidized butadiene, maleated butadiene, butadiene-
Low molecular weight liquid to high molecular weight elastic rubbers such as acrylonitrile copolymer, polychloroprene, butadiene-styrene copolymer, polyisoprene, butyl rubber, fluororubber, natural rubber; polyethylene, polypropylene, polybutene, poly-4-methyl Penten, polystyrene, AS
Resin, ABS resin, MBS resin, styrene-isoprene rubber,
Polyethylene-propylene copolymer, 4-fluoroethylene-
6-fluorinated ethylene copolymers; high molecular weight prepolymers or oligomers such as polycarbonate, polyphenylene ether, polysulfone, polyester, and polyphenylene sulfide; and polyurethane are exemplified and used as appropriate. In addition, other known organic and inorganic fillers,
Various additives such as dyes, pigments, thickeners, lubricants, defoamers, dispersants, leveling agents, photosensitizers, flame retardants, brighteners, polymerization inhibitors, and thixotropic agents may be used as desired. They are used in an appropriate combination. If necessary, the compound having a reactive group is appropriately blended with a curing agent and a catalyst.

The copper-clad board used in the present invention can contain an insulating inorganic filler in the thermosetting resin composition. Particularly for carbon dioxide laser drilling, 10 to 80% by weight, preferably 20 to 70% by weight is added in order to make the shape of the hole uniform. The kind of the insulating inorganic filler is not particularly limited. Specific examples include talc, calcined talc, aluminum hydroxide, magnesium hydroxide, kaolin, alumina, wollastonite, synthetic mica, and the like, and one or more kinds are used in combination.

The thermosetting resin composition of the present invention can be cured by heating itself, but has a low curing rate and is inferior in workability and economic efficiency. Can be used. The amount used is 0.005 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of the thermosetting resin.

The wavelength of the carbon dioxide laser is 9.3 to 10.6 μm
Is used. The energy is preferably 5 to 60 mJ / pulse, and a predetermined pulse is applied to form a hole. When drilling through holes and / or blind via holes, the same energy is radiated from the beginning to the end to form holes.
Either a method of increasing or decreasing the energy in the middle and a method of drilling may be used.

In drilling holes with the carbon dioxide laser of the present invention, burrs of the copper foil are generated around the holes. The method of etching and removing copper burrs generated in the holes is not particularly limited. For example, Japanese Patent Application Laid-Open Nos. 02-22887, 02-22896, and 02
-25089, 02-25090, 02-59337, 02-60189, 02-1
66789, 03-25995, 03-60183, 03-94491, 04-19
9592 and 04-263488, and a method of dissolving and removing a metal surface with a chemical (referred to as a SUEP method). The etching rate is generally 0.02 to 1.0 μm / sec. When etching the inner layer copper burrs by etching, a part of the surface of the copper foil is also etched away at the same time, preferably with a thickness of 2 to 7 μm, so that the subsequent copper-plated copper foil can be densely formed. Pattern can be formed, and a high-density printed wiring board can be obtained.

On the back surface of the copper-clad plate, it is possible to simply arrange a metal plate in order to prevent the laser machine table from being damaged by the laser when the hole penetrates. The resin layer to which at least a part is adhered is adhered to the rear surface copper foil of the copper-clad multilayer board, arranged, and peeled after drilling a through-hole for a through-hole.

In most cases, a resin layer having a thickness of about 1 μm remains on the surface of the processed inner surface of the copper foil where the resin of the surface and inner layer copper foils is adhered. This resin layer can be removed before etching by a generally known treatment such as a desmear treatment. However, if the liquid does not reach inside the small hole,
Residual removal of the resin layer remaining on the surface of the inner copper foil may occur, resulting in poor connection with copper plating. Therefore, more preferably, the inside of the hole is first treated in a gas phase to completely remove the residual layer of the resin, and then the inside of the hole and the front and back copper foil burrs are removed by etching. As the gas phase treatment, generally known treatments can be used, and examples thereof include a plasma treatment and a low-pressure ultraviolet treatment. As the plasma, low-temperature plasma in which molecules are partially excited by a high-frequency power source and ionized is used. For this, high-speed processing using ion bombardment and gentle processing using radical species are generally used, and reactive gases and inert gases are used as processing gases. Oxygen is mainly used as the reactive gas, and the surface is scientifically treated. As the inert gas, an argon gas is mainly used. Using this argon gas or the like, physical surface treatment is performed. Physical treatment uses ion bombardment to clean the surface. The low ultraviolet ray is an ultraviolet ray having a short wavelength region, and irradiates a short wavelength region having a peak at 184.9 nm and 253.7 nm, and decomposes and removes the resin layer.

The inside of the hole can be subjected to ordinary copper plating.
% Or more can be filled.

[0025]

The present invention will be specifically described below with reference to examples and comparative examples. Unless otherwise specified, “parts” indicates parts by weight.

Example 1 900 parts of 2,2-bis (4-cyanatophenyl) propane,
100 parts of (maleimidophenyl) methane are melted at 150 ° C,
The mixture was reacted for 4 hours with stirring to obtain a prepolymer. This was dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide. Add bisphenol A type epoxy resin (trade name: Epicoat 1001, Yuka Shell Epoxy Co., Ltd.)
) And 600 parts of a cresol novolac type epoxy resin (trade name: ESCN-220F, manufactured by Sumitomo Chemical Co., Ltd.) were uniformly mixed and dissolved. Further, as a catalyst, zinc octylate 0.4
2,000 parts of an inorganic filler (trade name: calcined talc, Nippon Talc Co., Ltd., average particle size 4 μm), and 8 parts of black pigment, and uniformly stirred and mixed to prepare Varnish A. Obtained. This varnish is impregnated with a 100 μm thick glass woven fabric and
It dried at ° C, and prepared the prepreg (prepreg B) whose gel time (at 170 ° C) was 102 seconds and the content of the glass cloth was 50% by weight.

A 12 μm thick double-sided treated copper foil is treated with a nickel alloy treatment (Japan Energy Co., Ltd. Y treatment), and an opposite side end of a 530 mm square copper foil is placed on a 300 μm thick aluminum plate. A copper foil C with a carrier having 10 mm adhered to one side of an aluminum plate and a copper foil D having a carrier attached to both sides of an aluminum plate were prepared. The copper foil C with carrier is arranged on the upper and lower outer sides so that the copper foil faces the side where the two prepregs B are arranged, and the copper foil D with carrier and the two prepregs B are alternately arranged on the inner side. A stainless steel plate with a thickness of 2 mm and a cushion on the outside of the plate are placed between hot plates (Fig. 1).
Laminate molding was performed for 2 hours under a vacuum of 0 kgf / cm ² and 30 mmHg or less to obtain a double-sided copper-clad laminate E. Note that between the hot plates, 20 sheets of double-sided copper-clad boards were put.

On the other hand, a resin in which polyvinyl alcohol is dissolved in water is applied to one side of a 50 μm-thick aluminum foil,
After drying at 10 ° C. for 20 minutes, a backup sheet F having a coating film having a thickness of 20 μm was prepared.

A backup sheet F is placed below the copper-clad laminate E with double-sided copper foil (FIG. 2 (1)), and irradiated directly from above with a carbon dioxide gas laser at an output of 15 mJ / pulse for 6 shots. 900 holes having a diameter of 100 μm were formed in a 50 mm square, and this was used as one block to form through holes of 70 blocks (FIG. 2 (2)). Remove the lower backup sheet,
The SUEP solution was sprayed at a high speed to dissolve and remove the burrs on the front and back, and at the same time, the copper foil on the front and back layers was dissolved to 4 μm (FIG. 2).
(3)). After desmearing, copper plating is applied to 15 µm (Fig. 2 (4)), and a circuit (line / space = 50/50 µm) is formed by an existing method, and pads for solder balls are formed.
At least a semiconductor chip portion, a bonding pad portion,
Except for the solder ball pad portion, the substrate was covered with a plating resist, plated with nickel and gold, and a printed wiring board was prepared. Tables 1 and 2 show the evaluation results of this printed wiring board.

Example 2 300 parts of an epoxy resin (trade name: Epikote 1001, Yuka Shell Epoxy Co., Ltd.) and an epoxy resin (trade name: ESC
N220F, manufactured by Sumitomo Chemical Co., Ltd.) 700 parts, dicyandiamide
35 parts, 1 part of 2-ethyl-4-methylimidazole was dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide,
A varnish was obtained by uniformly stirring and mixing. This is impregnated in a glass woven fabric having a thickness of 100 μm, dried, impregnated in a prepreg G having a gelling time of 150 seconds, a resin flow of 11 mm, and containing 48% by weight of a glass cloth, and a glass cloth having a thickness of 50 μm and dried. Gel time 170
In seconds, a prepreg H having a glass cloth content of 31% by weight was prepared.

Using one prepreg G, 35 μm
m of electrolytic copper foil was placed and laminated and formed at 190 ° C., 20 kgf / cm ² and 30 mmHg to obtain a double-sided copper-clad laminate I. After forming a circuit on the front and back of this plate and performing black copper oxide treatment, the above-described prepreg H was placed one at a time on each of the upper and lower sides, and the outside was treated on both surfaces.
A 2μm electrolytic copper foil (trade name: SQ-VLP, Mitsui Kinzoku Co., Ltd.) is laminated on a 200μm thick aluminum plate with a copper foil with a carrier with 10mm perimeter on the four sides on the periphery, and laminated as in Example 1. It was formed into a four-layer multilayer board. Thereafter, the aluminum plate is peeled off, and the top aluminum plate is left as it is.
Five layers are stacked, and a 1.6 mm paper phenol board is placed on the lower surface as a backup board.
A 0 μm through hole was made.

Further, after the uppermost aluminum plate of each of the four-layer plates was peeled off, the copper foil was directly irradiated with 3 shots at a pulse energy of 15 mJ of a carbon dioxide gas laser to open a blind via hole. After the entire surface was subjected to SUEP treatment to dissolve and remove to a thickness of 3 μm, it was placed in a plasma device and treated, and then subjected to desmear treatment with an aqueous potassium permanganate solution, followed by copper plating as in Example 1. Similarly, a printed wiring board was prepared. The evaluation results are shown in Tables 1 and 2.

COMPARATIVE EXAMPLE 1 Two prepregs B of Example 1 were used with a general thickness of 12 μm.
Using an electrolytic copper foil of m, lamination molding was performed under the same conditions as in Example 1 to prepare a double-sided copper clad board. Drilling was performed with a carbon dioxide laser under the same conditions as in Example 1 without attaching anything to the surface, but no holes were drilled.

Comparative Example 2 In Example 2, when a four-layer plate was prepared, an electrolytic copper foil and a prepreg were formed by a normal construction method using a stainless steel plate having a thickness of 2 mm without using an aluminum plate. Lamination molding was performed under the same conditions as in Example 2. In this case, many resin, dents and scratches were found on the copper foil surface. The surface with the scratches has been subjected to the surface treatment, and the resin and the dents often have short-circuits in the pattern formation. Holes were formed with a carbon dioxide laser under the same conditions as in Example 2, but no holes were formed.

Comparative Example 3 2,000 parts of epoxy resin (trade name: Epikote 5045), 70 parts of dicyandiamide, and 2 parts of 2-ethylimidazole were dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide, and the insulating inorganic filler of Example 1 was further dissolved. Was added and mixed with stirring to obtain a varnish. This is thickness 100
Impregnated into glass woven cloth of μm, dried and gelled for 140 seconds (at 170 ° C), prepreg J with glass content of 52% by weight, 180 seconds between gelation, glass content of 50μm thick glass cloth 35% by weight of prepreg K was obtained. This prepreg J
Using 2 sheets, place 12μm electrolytic copper foil on both sides, 180 ° C, 2
Laminate molding was performed for 2 hours under a vacuum of 0 kgf / cm ² and 30 mmHg or less to obtain a double-sided copper-clad laminate L. Circuits are formed on both sides of this laminated plate L, and after black copper oxide treatment, one prepreg K is placed on each side, and a general 12 μm copper foil is placed on the outside of the prepreg, and the thickness is 2 mm.
The stainless steel plate was used to set up 12 plates as a four-layer plate between hot plates, and laminated and formed under the same conditions as in Example 2.
Using this, a through hole having a hole diameter of 200 μm was formed by mechanical drilling in the same manner as in Example 2. No via hole was formed even when the carbon dioxide laser was directly irradiated.
This plate was plated with copper without being subjected to the SUEP treatment, and was similarly made into a printed wiring board. The evaluation results are shown in Tables 1 and 2.

COMPARATIVE EXAMPLE 4 Using the double-sided copper-clad laminate I of Example 2, the upper and lower copper foils were removed by etching so that the through holes in the inner layer had a hole diameter of 100 μm to form a circuit. The surface of the copper foil was treated with black copper oxide, one prepreg H was placed on the outside thereof, and a general 12 μm electrolytic copper foil was placed outside the prepreg H. Similarly, a four-layer plate was formed by laminating and molding. Using this multilayer board,
900 holes with a hole diameter of 100 μm were formed at positions on the surface where through holes were to be formed, and the copper foil was opened by etching. Similarly, 900 holes having a hole diameter of 100 μm were formed at the same position on the back surface (FIG. 3).
(1)). 70 blocks of 900 blocks per block, total 63,000
3 shots were applied from the surface with a carbon dioxide gas laser at an output of 15 mJ / pulse to form through holes for through holes (FIG. 3 (2)). Thereafter, in the same manner as in Comparative Example 3, a desmear treatment was performed once without performing the SUEP treatment, and the copper plating was applied to a thickness of 15 μm.
Example 2 (FIG. 3 (3)), a circuit was formed on both sides,
A printed wiring board was prepared in the same manner as described above. The evaluation results are shown in Tables 1 and 2.

Comparative Example 5 A double-sided laminated plate was obtained in the same manner as in Example 1, except that the aluminum carrier was not used. However, large irregularities occurred on the surface of the copper foil, and it was impossible to form a fine pattern.

[0038]

[Table 1]

[0039]

[Table 2]

<Measurement method> 1) Misalignment of front and back hole positions 70 blocks (63,000 holes in total) were prepared with 900 holes / block of holes having a hole diameter of 100 or 200 μm. CO2 laser and
Drill holes with a mechanical drill and / or the time required to drill 63,000 holes in one copper-clad plate.
When a land of 00 μm was formed, the maximum value of the gap between the copper foil for land and the hole and the deviation from the hole wall of the inner layer copper foil was shown. 2) Cut and short circuit pattern In the examples and comparative examples, a board without holes was created in the same way, a comb pattern of line / space = 50 / 50μm was created, and 200 patterns were etched with a magnifying glass. Was visually observed, and the total of the broken pattern and the short-circuited pattern was shown in the molecule. 3) Glass transition temperature Measured by the DMA method. 4) Through hole heat cycle test Create a land diameter of 300μm in each through hole hole, connect 900 holes alternately front and back, one cycle is 260 ° C, solder, immersion 30 seconds → room temperature, 5 minutes, up to 500 cycles The maximum value of the rate of change of the resistance value was shown. 5) Migration resistance (HAST) 150 μm between the hole walls
50 pieces were connected in parallel, and 100 pieces were prepared. After processing at 130 ° C., 85% RH and 1.8 VDC for a predetermined time, the pieces were taken out and the insulation resistance value between through holes was measured.

[0041]

According to the present invention, a carbon dioxide gas laser having sufficient energy to process a copper foil is directly irradiated onto a copper-clad laminate obtained by laminating and forming a copper foil subjected to a double-sided treatment for at least an outer layer. A method for forming a through hole and / or a blind via hole having a hole diameter of 80 to 150 μm is provided. ADVANTAGE OF THE INVENTION According to the method of this invention, the processing speed is remarkably faster compared with mechanical drilling, and the hole formation method which can improve productivity significantly is provided. Also, after that, at the same time as dissolving and removing the copper foil burrs generated in the holes, a part of the surface of the copper foil is dissolved, preferably to 2 to 7 μm, so that in the subsequent plating up by copper plating, fine A pattern can be formed, and a high-density printed wiring board can be formed. In addition, by adding an insulating inorganic filler, the pore shape is improved, there is no gap or gap with the land copper foil, and in addition, a polyfunctional cyanate compound as a thermosetting resin composition, A printed wiring board obtained by using a resin composition containing an acid ester prepolymer as an essential component has excellent heat resistance, migration resistance, heat resistance after moisture absorption, and the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of laminating and molding a copper-clad board according to a first embodiment.

FIG. 2 is a through hole drilling (2) for a through hole in a laminated copper clad laminate of Example 1 using a carbon dioxide gas laser, and SUE.
Removal of burrs by P and etching of surface copper foil (3),
It is a process figure of copper plating (4).

FIG. 3 is a process diagram of drilling and copper plating of a double-sided copper-clad multilayer board of Comparative Example 4 with a carbon dioxide gas laser (without SUEP).

[Explanation of symbols]

 a Aluminum plate for adhering copper foil on both sides b Copper foil treated on both sides c Prepreg B d Inner layer copper foil e Glass cloth substrate laminate f Polyvinyl alcohol layer g Aluminum foil for backup sheet h Burr of generated copper foil i Carbon dioxide gas Laser-drilled through-holes j Outer layer copper foil thinned by etching k Copper-plated through-hole l Inner layer copper foil with misalignment m Copper-plated 4-layer plate through-hole n Through-hole hole wall and land copper Gap between foil

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taro Yoshida 6-1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi Gas Chemical Co., Ltd. Tokyo factory F-term (reference) 4E068 AA04 AF00 CA02 DA11 DB02

Claims (7)

[Claims] 1. A carbon dioxide laser having an energy sufficient for processing a copper foil is directly irradiated by pulse oscillation from a treatment surface of a copper-clad board using at least an outer layer of a double-sided treated copper foil to form a through hole and And / or forming a blind via hole in the copper clad board. . 2. The carbon dioxide laser energy is 5-60.
2. The method for forming a hole in a copper-clad board according to claim 1, which is mJ. 3. The copper according to claim 1, wherein, after the carbon dioxide gas laser drilling, the copper foil burrs generated around the hole are removed and a part of the copper foil surface is planarly etched. Method of forming holes in upholstery. 4. The resin composition for a copper-clad board comprising a polyfunctional cyanate compound and a cyanate ester prepolymer as essential components.
The method for forming a hole in a copper-clad board according to the above. 5. The hole in a copper clad board according to claim 1, wherein the thermosetting resin of the copper clad board contains 10 to 80% by weight of an insulating inorganic filler. Forming method. 6. The copper according to claim 1, wherein the treatment of at least the surface of the double-sided treated copper foil that does not adhere to the resin surface is a nickel treatment or an alloy treatment thereof. Method of forming holes in upholstery. 7. A copper-clad plate is formed by laminating a double-sided treated copper foil partially adhered to one surface of a protective metal plate, with the copper foil side facing the resin side and positioned as the outermost layer. The method for forming a hole in a copper clad board according to claim 1, 2, 3, 4, 5, or 6.