JP2001230518A - Method for forming hole by using carbon dioxide gas laser and its post-treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a hole for preventing contamination of a copper foil surface of a copper clad plate, when a hole is to be formed by using carbon dioxide gas laser. SOLUTION: After an etching film or liquid state etching resist is arranged on the surface of the copper clad plate, and only the portion of a target mark is developed, the surface copper foil is etched and eliminated. The target mark in this portion is read with a CCD camera, and the film or the resist is irradiated directly with a high output carbon oxide gas laser, preferably selected from 10-60 mJ, thereby working and removing an outer layer copper foil and an inner layer copper foil, and forming a through-hole and/or a blind via hole. Thus, the through-hole and/or the blind via hole can be formed directly using the carbon dioxide gas laser, in such a manner that the surface layer copper foil is not contaminated. A high density printed wiring board can be obtained, using the copper clad plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a through hole and / or a blind via hole in a copper-clad laminate using a novel carbon dioxide laser. A printed wiring board using a copper-clad board having holes formed by this method can be used as a high-density small printed wiring board having small-diameter holes and a fine pattern, for use in a new semiconductor plastic package or the like. Suitable for use.

[0002]

2. Description of the Related Art Conventionally, in a high-density printed wiring board used for a semiconductor plastic package or the like, a through hole is formed by a mechanical drill. 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. The blind via hole has been formed by etching the copper foil at the position where the hole is to be drilled in advance and then using a low-energy carbon dioxide laser. Further, the target mark was formed at the same time as the etching.
With this method, only blind via holes can be formed,
Since the through holes are separately formed by mechanical drilling or the like, the number of steps is large, and work efficiency is poor. As for the method of forming through holes, holes of the same size are made in advance by using a negative film on the front and back copper foils using a negative film, and similar holes are formed in the inner layer copper foil by etching in advance. There is a method of arranging the holes and forming a hole penetrating the front and back with a carbon dioxide gas laser. However, this method has drawbacks such as misalignment of the inner layer copper foil, a gap between the upper and lower holes and the land, poor connection and inability to form a land on the back surface.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a hole in a copper clad board which has solved the above-mentioned problems.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method for forming a through hole and / or a blind via hole in a copper clad plate by a carbon dioxide gas laser. An etching film or a liquid etching solder resist layer is formed on the surface of a copper-clad board that has been subjected to a simple copper foil surface treatment. While leaving the film or resist as it is, reading this target mark with a CCD camera and confirming the position, irradiate a carbon dioxide laser beam with enough energy to process the copper foil directly from above the film or resist, This is a method of forming through holes and / or blind via holes. The copper foil surface treatment is not particularly limited as long as it can be drilled by irradiating a carbon dioxide laser. Preferably, nickel treatment, nickel alloy treatment, metal oxide treatment, chemical solution treatment and the like can be used. After drilling, the film or resist on the surface is removed, and the copper foil burr generated around the hole is removed by etching with a chemical solution. At the same time, the surface copper foil is partially etched away in the thickness direction. After removal,
Using a double-sided copper-clad board obtained by plating this with copper plating, circuits are formed on the front and back sides, and a printed wiring board is formed by a standard method. In order to make the circuit on the front and back fine, the thickness of the copper foil on the front and back layers is preferably 2 to 7 μm, preferably 3 to 5 μm. Therefore, a high-density printed wiring board can be produced. Furthermore, the processing speed was remarkably faster than that obtained by drilling, and a product having good productivity and excellent economic efficiency was obtained. The thickness of the copper foil is 3-5μ from the beginning
In the case of a thin film having a thickness of m, the etching film or the liquid etching solder resist is left as it is after drilling with a carbon dioxide gas laser, and the film or resist is dissolved and removed with an alkaline chemical after removing the copper foil burr with an acidic etching solution. .

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is directed to a method of forming a hole in a copper foil directly by a carbon dioxide gas laser, which is free from contamination caused by a workpiece such as a copper foil, a glass fiber or a resin falling on the surface of the copper foil. The present invention relates to a method for drilling a veneer. First, an etching film or a liquid etching solder resist is applied to the surface of a copper-clad or multilayer board obtained by using a copper foil subjected to a copper foil surface treatment capable of forming a hole by directly irradiating a carbon dioxide gas laser. Attach. After the film or the resist at the target mark portion is developed and removed, at least the copper foil at the target mark portion is removed by etching. Of course, other portions may be removed by etching. Then, the position determined by reading the target mark by the CCD camera is irradiated with a carbon dioxide laser having sufficient energy to process the copper foil, and a through hole and / or
Or make a blind via hole. After that, the film or the resist is removed, the copper foil burrs generated in the holes are dissolved and removed with a chemical solution, and the copper foil of the front and back layers is partially removed in the thickness direction. Thereafter, a printed wiring board is formed by a generally known method.

[0006] A target mark (alignment mark) has a size readable by a CCD camera.
Preferably, it refers to a circular mark. This mark is read first, the dimension is corrected by a function programmed to automatically perform the dimension correction, and a hole is formed in a predetermined position by a laser. As a result, the dimension is automatically corrected so that the position of the hole is located at the designed position, no deviation occurs, and the occurrence of defects is eliminated. The shape of the hole is not particularly limited, but is preferably circular. Specifically, a method of drilling a hole to make this hole a target mark, a method of leaving a copper foil in a circular shape by etching, a method of exposing a resin surface by etching a copper foil in a circular shape and forming this as a target mark A generally known method such as a method for performing the method can be employed. In the case of a double-sided copper clad board, it is formed on the outer layer. In the case of a multilayer board, it is generally formed on an inner layer board, and even if there is shrinkage of the inner layer plate during multilayer molding,
Dimension correction can be automatically performed by reading with a CCD camera compared to the design. The formation position is formed at least at two corners, preferably at least three corners of the substrate.

[0007] The etching film is a resin film used when etching a copper foil.
Acrylate groups and carboxyl groups (-
(COOH) in the molecule. This film is heated, laminated and adhered to the surface of the copper-clad board, and a negative film is placed on this film so that the part where the copper foil is left transmits light, and ultraviolet light is irradiated from above. Thereafter, an alkaline developing solution (generally, a 1% by weight aqueous solution of sodium carbonate) is sprayed to dissolve and remove the portions not irradiated with light, and the copper foil is etched and removed. After piercing with a carbon dioxide laser, the etching film is dissolved and removed with an alkaline chemical (aqueous sodium hydroxide solution). Of course, generally known films such as an etching film containing other functional groups can be used.

[0008] A liquid etching solder resist is used for etching a copper foil, which is made by mixing a resin containing an acrylate group and a carboxyl group in a molecule with another liquid compound or the like, similarly to an etching film. It is a composition used for. This is applied on a copper-clad plate, irradiated with ultraviolet rays through a negative film, and the portions not irradiated with the ultraviolet rays are dissolved and removed with an alkaline developer, and then the copper foil is removed by etching. Of course, a generally known liquid etching solder resist other than this form can also be used.

In the present invention, there is no particular limitation on the method of performing a surface treatment capable of drilling by irradiating a carbon dioxide gas laser directly onto a copper foil. For example, nickel treatment or nickel alloy treatment, black copper oxide treatment Metal oxide treatment and chemical liquid treatment such as CZ treatment (Mec). Nickel treatment includes treatment by a generally known method such as nickel plating and nickel vapor deposition. The nickel alloy treatment includes a generally known treatment of nickel-chromium, nickel-chromium-iron, and the like. Although the thickness of the treatment layer is not particularly limited, it is generally 1 to 5 μm. The surface may have irregularities, but considering the subsequent thinning of the copper foil by the chemical solution, the irregularities are preferably as small as possible.

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 can be used from the beginning, but preferably, a 9-12 μm thick copper foil is laminated and formed, and then subjected to hole processing with a carbon dioxide gas laser. The copper foil of the surface layer is thinned with an etching solution to 2 to 7 μm, preferably 3 to 5 μm.

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 point of the 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 preferred, and a polyfunctional cyanate resin composition is preferred from the viewpoints of moisture resistance, migration resistance, electrical properties after moisture absorption, and the like.

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. These shapes are not particularly limited, and are spherical,
Examples include irregular shapes and fibrous shapes.

When the thermosetting resin composition itself is cured by heating but has a low curing rate and is inferior in workability and economy, a known thermosetting catalyst is used for the thermosetting resin used. 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.

Using a carbon dioxide laser, the pore size is 80 to 180 μm.
When drilling through holes and / or blind via holes, the surface etching film or liquid etching solder resist is left as it is, and from above, preferably 10 to 60
Drilling is performed by directly irradiating a carbon dioxide laser with an output of mJ. From the perspective of preventing copper foil contamination by copper and organic matter based on drilling, by piercing with the surface film or resist as it is, the scattered residue falls on the film or resist, preventing copper foil contamination. It is valid. The wavelength of the carbon dioxide laser is 9.3 to 10.6 μm.
When drilling holes having a hole diameter of 80 to 180 μm, the energy is preferably 10 to 60 mJ, and the holes are irradiated with a predetermined pulse. When drilling through holes and / or blind via holes,
Either a method of piercing by irradiating the same energy from the beginning to the end or a method of piercing by increasing or decreasing the energy on the way may be used.

In drilling holes by the carbon dioxide laser of the present invention, burrs of the copper foil are generated around the holes. The method for etching and removing copper burrs generated in the holes is not particularly limited. For example, JP-A Nos. 02-22887, 02-22896, and
02-25089, 02-25090, 02-59337, 02-60189, 02
-166789, 03-25995, 03-60183, 03-94491, 04-
According to a method of dissolving and removing a metal surface with a chemical (referred to as a SUEP method) disclosed in Japanese Patent Application Laid-open No. 1995-92, 04-263488.
The etching speed is generally 0.02 to 1.0 μm / sec.
Also, when etching the copper foil burrs of the inner layer, a part of the surface of the copper foil is also etched away at the same time, and the thickness is 2 to 7 μm.
By setting the thickness to m, preferably 3 to 5 μm, a fine pattern can be formed on the subsequent copper-plated copper foil, 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 has been adhered is arranged by being adhered to the copper foil on the back surface of the copper-clad multilayer board.

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 in advance by a generally known treatment such as desmear treatment before etching. However, if the liquid does not reach the inside of the small-diameter hole, the removal of the resin layer remaining on the surface of the copper foil of the inner layer remains. 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. Although the inside of the hole can be subjected to ordinary copper plating, the inside of the hole can be partially filled with copper plating, preferably at least 80% by volume. In drilling, an excimer laser, a YAG laser or the like can be used. Further, the combined use of the lasers is also possible.

[0024]

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.

Electroplated copper foil having a thickness of 3 μm on both sides of a 12 μm-thick double-sided copper foil treated with a nickel alloy (also referred to as Japan Energy Co., Ltd. Y-treatment, LD foil) is applied on the front and back of the four prepregs B. Place a 1.5mm stainless steel plate on the outside and put it between 15 sets of hot plates, 200 ℃, 20kgf / c
Laminate molding was performed for 2 hours under a vacuum of m ² and 30 mmHg or less to obtain a double-sided copper-clad laminate C. An etching film having a thickness of 20 μm is laminated and adhered at 95 ° C. (FIG. 1 (1)), and a negative film is applied thereon so that only the target marks at the four corners are not exposed to UV light. And then developed to dissolve and remove the film at the target mark,
From above, the surface copper foil was removed by etching with an etchant, and a hole having a diameter of 0.5 mm was formed to obtain a copper-clad laminate D (FIG. 1).
(2)).

On the other hand, a resin obtained by dissolving polyvinyl alcohol in water is applied to one side of an aluminum foil having a thickness of 50 μm.
After drying at 10 ° C. for 20 minutes, a backup sheet E having a coating film having a thickness of 20 μm was prepared. A backup sheet E is placed on the back side of the copper-clad laminate D, 900 holes with a diameter of 100 μm are cut directly from the top of the copper-clad laminate D within a 50 mm square from the top of the copper-clad laminate D on which an etching film is attached. Irradiated 3 shots at 20 mJ and 3 shots at 20 mJ to make through holes of 70 blocks (FIG. 1 (3)). The surface etching film and the lower backup sheet were removed, and a SUEP solution was sprayed at a high speed to dissolve and remove burrs on the front and back surfaces, and at the same time, the copper foil on the surface layer was dissolved to 4 μm (FIG. 1 (4)). After desmear treatment and copper plating 15μm adhesion (Fig. 1
(5)), circuit using existing method (line / space = 50/5)
0 μm), pads for solder balls, etc. were formed, covered with a plating resist except for at least the semiconductor chip portion, the bonding pad portions, and the solder ball pad portions, and plated with nickel and gold to produce a printed wiring board. Table 1 shows the evaluation results of the printed wiring board.

Example 2 300 parts of epoxy resin (trade name: Epicoat 1001, manufactured by Yuka Shell Epoxy Co., Ltd.) and 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,
Varnish F was obtained by uniformly stirring and mixing. This is 100μm thick
Impregnated in glass woven cloth, dried, gelled for 150 seconds, prepreg G with a glass cloth content of 48% by weight, impregnated in glass cloth with a thickness of 50 μm, dried and gelled for 170 seconds, glass cloth Prepreg H having a content of 31% by weight was prepared.

Using one prepreg G, the thickness is
Place 12μm general electrolytic copper foil, 190 ° C, 20kgf / cm ² , 30mmH
g to obtain a double-sided copper-clad laminate I. At the same time as forming the circuit on the front and back of this plate, target marks having a diameter of 0.5 μm were formed at the four corners, black copper oxide treatment was performed, and one prepreg H was placed on each of the upper and lower sides.
A general electrolytic copper foil having a thickness of μm was arranged and similarly laminated and formed to form a four-layer multilayer board. Thereafter, the copper foil on the upper surface is subjected to CZ treatment (Mec Corporation), and a liquid etching resist
And dried to remove the solvent (Fig. 2
(1)) The resist on the target mark on the inner layer plate was developed and removed with a diameter of 3 mm. After removing the copper foil by etching,
The backup sheet E is placed below this plate, and the target mark (l) on the inner layer plate where copper foil is etched
Was read by a CCD camera (FIG. 2 (2)), and a through-hole (e) was formed by irradiating two shots with a carbon dioxide laser output of 15 mJ and two shots at 20 mJ from above the liquid resist. Further, a blind via hole (q) was opened by irradiating three shots at an output of 15 mJ of a carbon dioxide gas laser (FIG. 2 (3)).

After removing the surface liquid etching resist and the backup sheet, the whole is subjected to a SUEP treatment to a thickness of 3
After dissolving and removing to a thickness of μm (FIG. 2 (4)), desmear treatment was performed with an aqueous solution of potassium permanganate, copper plating was similarly performed (FIG. 2 (5)), and a printed wiring board was similarly formed. Table 1 shows the evaluation results.

COMPARATIVE EXAMPLE 1 Using the copper-clad plate I of Example 2, a hole was drilled with a carbon dioxide laser under the same conditions as in Example 2 without attaching anything to the surface. Did not go.

Comparative Example 2 A hole was formed on the multilayer plate subjected to the CZ treatment of Example 2 with a carbon dioxide laser under the same conditions as in Example 2. Copper residues generated during drilling were adhered to the copper foil.

Comparative Example 3 2,000 parts of an epoxy resin (trade name: Epicoat 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
prepreg J with a gelling time of 140 seconds (at 170 ° C) and a glass content of 52% by weight
Using glass cloth of 50μm thickness, glass content 35 weight
%, And a prepreg K having a gel time of 180 seconds was obtained. Using two sheets of this prepreg J, put a general electrolytic copper foil of 12 μm thickness on both sides, 180 ° C., 20 kgf / cm ² , laminate molding under vacuum of 30 mmHg or less for 2 hours to obtain a double-sided copper-clad laminate L Was. Circuits were formed on both sides of this laminated plate L, after black copper oxide treatment, one prepreg K was placed on each side, and a general electrolytic copper foil having a thickness of 12 μm was placed outside the prepreg K. Lamination molding was performed under the conditions.
Using this, a through hole having a hole diameter of 150 μm was formed in the same manner with a mechanical drill. With the carbon dioxide laser, no via hole was formed even when the beam was directly irradiated on the copper foil surface. Copper plating was performed without performing the SUEP treatment, and a printed wiring board was similarly formed. Table 1 shows the evaluation results.

Comparative Example 4 Using the double-sided copper-clad laminate I of Example 2 (FIG. 3 (1)), 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. After forming the circuit, the surface of the copper foil is treated with black copper oxide, one prepreg H is placed on the outside thereof, and a general electrolytic copper foil having a thickness of 12 μm is arranged on the outside thereof, as in Example 2. Lamination molding under the conditions of 4
A laminated plate was created. Using this multilayer board, 900 holes having a hole diameter of 100 μm were formed in the position of the surface where the through hole was to be formed by etching the copper foil. Similarly, the hole diameter is 100 μm at the same position on the back side
900 holes were made (FIG. 3 (2)). 900 patterns
A total of 63,000 holes in 70 blocks were shot from the surface with a carbon dioxide gas laser at an output of 15 mJ for 4 shots to make through holes (Fig. 3 (3)). Thereafter, in the same manner as in Comparative Example 4, a desmear treatment was performed once without performing the SUEP treatment, and the copper plating was applied to a thickness of 15 μm.
m (FIG. 3 (4)), circuits were formed on the front and back, and a printed wiring board was prepared in the same manner. Table 1 shows the evaluation results.

[0035] Table Example 1 Item implementation example comparisons 1 2 3 4 top- land copper foil with clearance ([mu] m) 0 0 0 22 shift over the hole positions of the inner layer 0 0 36 ([mu] m) Pattern breakage and 0 / 200 0/200 55/200 52/200 Short (pcs) Glass transition temperature (℃) 235 160 139 160 Through-hole heat cycle test (%) 100 cycles 1.1 1.2 1.6 3.9 300 cycles 1.2 1.4 1.8 6.5 500 cycles 1.4 1.6 2.6 29.9 drilling time (min) 19 14 630 over migration resistance (HAST) (Omega) normal 3x10 ¹¹ over 1x10 ¹¹ over ^{200hrs. 8x10 8 <10 8 500hrs} . 7x10 8 over 700hrs. 6x10 ⁸ 1000hrs. 5x10 ⁸

<Measurement method> 1) Misalignment of the front and back holes The hole with a hole diameter of 100 or 150 μm (mechanical drill)
70 blocks (63,000 holes total) were prepared as 00 holes / block. The time required for drilling holes with a carbon dioxide laser and a mechanical drill to make 63,000 holes in one copper-clad board, the gap between the copper foil for front and back lands and the hole, and the maximum value of the deviation from the inner layer copper foil showed that. 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 250 μm for 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) A total of 50 copper-plated through-holes with a hole diameter of 100 μm or 150 μm (mechanical drilling) are alternately connected, one on each side, a total of 50 holes. Make a total of 100 sets, 130 ℃, 85% R
After processing at H, 1.8 VDC for a predetermined time, the samples were taken out and the insulation resistance between through holes arranged in parallel was measured.

[0037]

According to the present invention, an etching film or a liquid etching solder resist is formed on a copper-clad plate having a surface treatment capable of making holes by irradiating a carbon dioxide gas laser directly onto the copper foil. After forming and removing those target mark portions, the copper foil on the surface layer is removed by etching, the target mark is read with a CCD camera as it is, the position is determined, and the copper foil is directly removed from the film or resist. A method is provided for forming through holes and / or blind via holes by irradiating sufficient carbon dioxide laser energy to remove them. ADVANTAGE OF THE INVENTION According to the method of this invention, it can prevent that the residue of copper foil, glass fiber, resin, etc. which scattered at the time of drilling falls and adheres. After that, the copper clad board from which the surface film or the resist has been removed has copper foil burrs around the holes. Since this copper foil burr is difficult to remove by mechanical polishing, it can be completely removed by etching with a chemical solution, and there is no protrusion in the subsequent copper plating, and one with excellent hole connection reliability can get. Further, when the copper foil burrs are removed by etching, a part of the surface copper foil is removed by etching in the thickness direction, and the thickness is preferably 2 to 7 μm, more preferably 3 to 5 μm. By doing so, a fine pattern can be formed in the subsequent pattern formation by copper plating, and a high-density printed wiring board without short-circuits and pattern breaks can be obtained.

Furthermore, forming a through hole and / or a blind via hole having a hole diameter of 80 to 180 μm with a carbon dioxide gas laser is much faster than an excimer laser, a YAG laser, and a mechanical drilling, and greatly reduces productivity. Can be improved. In addition, by adding an insulating inorganic filler to the resin, the shape of the hole is improved, and there is no gap between the land copper foil and the hole, and a material having excellent hole connection reliability is obtained. In addition, a printed wiring board obtained by using a polyfunctional cyanate compound as a thermosetting resin composition and a resin composition containing the cyanate ester prepolymer as an essential component has heat resistance and migration resistance. And so on.

[Brief description of the drawings]

FIG. 1 Double-sided copper-clad laminate (1) with an etching film of Example 1 and target marks read by a CCD camera
FIG. 2B is a process diagram of (2), opening a through hole from the etching film with a carbon dioxide laser (3), etching removal of copper foil burrs and surface copper foil by SUEP (4), and copper plating (5).

FIG. 2 shows a four-layer plate (1) with a liquid etching solder resist of Example 2 and a target mark read by a CCD camera.
FIG. 4B is a process diagram of (2), drilling of through holes and blind via holes by a carbon dioxide laser (3), etching of copper foil burrs and surface copper foil by SUEP (4), and copper plating (5).

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 Double-sided copper-clad laminate with an etching film attached B Four-layer copper-clad plate with a liquid etching solder resist a Etching film b Copper foil treated with nickel alloy that can be drilled with a carbon dioxide gas laser c CCD camera d Etching Formed target mark e Through hole portion drilled by carbon dioxide gas laser f Surface copper foil burr generated g SUEP treated through hole portion h Thinly etched surface copper foil i Copper plated through hole j Copper plating k Residue scattered and dropped at the time of drilling with carbon dioxide gas laser l Target mark of copper foil formed on inner layer m Liquid etching solder resist n Copper foil with surface treated by MEC o Copper foil on target mark was removed Location (Read the target mark of the inner layer from this part) p Inner layer copper foil pattern q Carbon dioxide gas Blind Via Hole Drilled by Copper Hole r Copper Foil Burr of Blind Via Hole Generated s Inner Layer Copper Foil Burr t Copper Plated Blind Via Hole u Outer Layer Copper Foil Etched for Through Hole Drilling v Through Hole Drilling Inner layer copper foil etched away for use w Inner layer copper foil with displacement x Copper plated through hole with poor hole shape y Outer layer copper foil with displacement

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/06 H05K 3/06 CF term (Reference) 4E068 AF01 AF02 DA11 DB02 5E338 AA02 AA03 DD12 DD32 EE41 5E339 AB02 AC01 AD03 AE01 BC02 BE11 CC10 CD01 CE12 CE15 CF17 CG01 DD03 EE01 EE10

Claims (4)

[Claims] 1. An etching film or a liquid etching solder resist is formed on a copper-clad plate having a surface treatment capable of forming a hole by direct irradiation of a copper gas laser onto a copper foil, and the film is formed on the copper-clad plate. Alternatively, after developing and removing the target mark portion of the resist, the surface copper foil at the removed portion is etched away, and then the target mark is read by a CCD camera, and sufficient carbon dioxide gas is used to remove the copper foil from the film or the resist. A hole making method using a carbon dioxide gas laser, which comprises directly irradiating laser energy to form a through hole and / or a blind via hole, and then removing the film or the resist. 2. The method according to claim 1, wherein the copper foil surface treatment is a nickel treatment, a nickel alloy treatment, a metal oxide treatment, or a chemical treatment. 3. An output of a carbon dioxide gas laser having an output selected from 10 to 60 mJ and a through hole having a hole diameter of 80 to 180 μm and / or
3. A method according to claim 1, wherein a blind via hole is formed. 4. The method according to claim 1, wherein after removing the surface film or resist, the copper foil burrs generated around the holes are dissolved and removed with a chemical solution, and at the same time, a part of the surface copper foil is dissolved. 3. The method for treating copper foil after drilling with a carbon dioxide laser according to 3.