JP2002353638A - Multi-layer copper-clad board suitable for mass productive carbon dioxide laser boring process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost multi-layer copper-clad board having a reference mark for boring formed thereon and having good mass productivity and workability for forming a small diameter blind via-hole by directly irradiating the multi-layer copper-clad board with a carbon dioxide laser beam after removing copper foil from the surface thereof beforehand. SOLUTION: The multi-layer copper-clad board is manufactured by forming a reference mark at the end part of inner layer copper foil and forming a lamination so that the laminated material does not cover the reference mark. A small diameter blind via-hole can be bored by irradiating the multi-layer copper-clad board with a dioxide laser beam while reading the exposed reference mark by a CCD camera without removing the copper foil and the insulating layer on the reference mark after forming the lamination. The hole can be formed with good mass productivity and workability at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer copper-clad board for forming a blind via hole by irradiating a part of a copper foil in advance with a carbon dioxide gas laser and then irradiating the part with a carbon dioxide gas laser. The printed wiring board obtained by using the same is used as a high-density small printed wiring board having a small diameter hole and a fine pattern formed thereon, for a new semiconductor plastic package, a new motherboard, and the like.

[0002]

2. Description of the Related Art Conventionally, when a blind via hole is formed with a carbon dioxide gas laser, a reference mark read by a CCD camera for making the hole is formed by processing a copper foil of an inner layer of a multilayer copper clad board. If necessary, apply a chemical treatment to the copper foil surface of the board, place a prepreg and copper foil on it, laminate it under heating and pressurization, and make a fiducial mark under the copper foil and insulating layer. In order to read this fiducial mark with a CCD camera, read the copper foil on the surface layer from the hardened resin layer by etching and remove it, or expose the fiducial mark by shaving the copper foil and insulating layer with a counterbore etc. Read this,
There were problems with workability, mass productivity, and cost.

[0003]

SUMMARY OF THE INVENTION In the present invention, when a part of copper foil of a multilayer copper clad board is pre-processed and a carbon dioxide laser is irradiated to form a hole, a reference mark read by a CCD camera is used. It is intended to provide a multilayer copper-clad board for manufacturing a high-density printed wiring board which is advantageous in terms of workability, mass productivity, and price without processing.

[0004]

When a part of the copper foil of the multilayer copper clad board is etched and removed, and a carbon dioxide laser is irradiated thereon to form a blind via hole, a reference mark read by a CCD camera is required. is there. This reference mark is made by processing copper foil at the end of the inner layer plate.In this case, the inner layer plate is slightly larger than the lamination size, a reference hole is formed in the protruding part, By preventing the resin from covering the reference mark, there is no need to pre-process this multilayer copper clad plate to expose the reference mark, there is no complexity in terms of workability, and the cost can be reduced in terms of price. A product excellent in mass productivity was obtained.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a copper foil portion for drilling a hole in a multilayer copper clad board is previously drilled by a known method such as etching, drilling, and YAG laser, and a carbon dioxide laser is irradiated from above. In the processing method to form a small diameter blind via hole, a reference mark that is a reference for irradiation at the time of laser irradiation is read with a CCD camera, and laser is irradiated at a distance from there, and drilling is performed. When processing the copper foil on the surface of the end of the inner layer board of the multilayer copper clad board, generally leave a circular copper foil with a diameter of 0.5 to 1.0 mmφ or form it by etching it into a circular shape, the size of this inner layer Make it slightly larger so that the reference mark at the end is not covered with the resin flow during lamination molding. In this way, after lamination molding, the hole can be formed while reading the fiducial mark as it is, without prior processing such as spotting the copper foil and the insulating layer on the fiducial mark.

[0006] The inner layer board of the multilayer copper clad board of the present invention is slightly larger than the size to be laminated. A reference mark is formed at this end. The B-stage resin composition sheet, which is a laminated material to be laminated, is made smaller than the fiducial mark so that the resin flows during lamination molding and is not covered. Generally, it should be 5 to 50 mm smaller.

[0007] The multilayer copper-clad board of the present invention is a generally known multilayer copper-clad board, and the inner layer board and the laminated material are each reinforced with a base material, a film base material, or a resin alone without a reinforced base material. Can be used. However, a glass-cloth-based copper-clad plate is preferred from the viewpoint of dimensional shrinkage and the like.

As the base material for the inner layer copper-clad board and the laminated material, generally known organic and inorganic woven fabrics and nonwoven fabrics can be used.
Specifically, E, S, D, M, NE
Examples include fibers such as glass. Also, as organic fiber,
Examples thereof include wholly aromatic polyamide, liquid crystal polyester, and polybenzazole fibers. 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 and the laminated material 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,
A polyfunctional cyanate resin composition is preferred from the viewpoint of electrical properties after moisture absorption.

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 combination as appropriate 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, acrylic rubber, fluoro rubber, natural rubber; polyethylene, polypropylene, polybutene, poly- 4-methylpentene, polystyrene, AS resin, ABS resin, MBS resin, styrene-isoprene rubber, polyethylene-propylene copolymer, 4-
Fluorinated ethylene-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 appropriately used. Further, generally known core-shell rubbers can also be used. In addition, other known organic and inorganic fillers, dyes, pigments, thickeners, lubricants, defoamers, dispersants, leveling agents, photosensitizers, flame retardants, brighteners, polymerization inhibitors, thixotropic Various additives such as imparting agents are used in combination as needed. If necessary, the compound having a reactive group is appropriately blended with a curing agent and a catalyst.

In the copper clad board used in the present invention, an insulating inorganic filler can be added to the thermosetting resin composition. Particularly, for carbon dioxide gas laser drilling, 10 to 79% by weight, preferably 15 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, glass components, and the like. Further, acicular inorganic and organic fillers can be added. A mixture of two or more species is used.

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 copper foil necessary for producing the copper clad board used in the present invention includes generally known electrolytic copper foil. As the copper foil, an electroplated copper foil having a thickness of preferably 3 to 12 μm is preferably used as an outer layer plate, and a copper foil having a thickness of 9 to 35 μm is preferably used for an inner layer plate.

The method for processing the surface copper foil of the multilayer copper-clad board is not particularly limited, and a generally known method can be used. For example, there are a method by etching, a method of making holes with a UV laser such as a YAG laser, a method of making holes with a mechanical drill, and the like. After processing and removing the surface copper foil, the insulating layer is processed by irradiating a carbon dioxide laser to form a blind via hole. The wavelength of CO2 laser is 9.3 ~ 1
0.6 μm is used. Energy is not particularly limited,
A predetermined pulse is preferably irradiated by pulse oscillation at 5 to 40 mJ to form a hole. After processing the copper foil, any of a method of irradiating holes with the same energy and a method of piercing by increasing or decreasing the energy on the way can be used.

In most cases, a resin layer of about 1 μm remains on the surface of the surface of the processed hole and the surface of the inner layer copper foil to which the resin has adhered. This resin layer can be removed in advance by a generally known treatment such as a 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. As the reactive gas, oxygen is mainly used, and the surface is chemically 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.
It can also be filled by volume% or more.

[0022]

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 diameter 1 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
After drying at ℃, the gelling time (at 170 ℃) 102 seconds, the content of glass woven fabric 50% by weight prepreg (prepreg B), the gelation time (at 170 ℃) 120 seconds, the content of glass woven fabric A prepreg (prepreg C) of 43% by weight was prepared. Piled 4 sheets of this prepreg B, placing an electrolytic copper foil having a thickness of 18μm to this ^{two-sided, 200 ℃, 20kgf / cm 2} , and 2 hours laminate molded under vacuum below 30 mmHg, both surfaces of 340x340mm and cut into Copper clad laminate D
I got

A double-sided circuit of this copper-clad laminate D is formed by a standard method, black copper oxide treatment is performed, a prepreg C having a size of 340 × 340 mm is placed on each of the front and back sides, and a 12 μm electrolytic copper foil is placed thereon. It arrange | positioned and laminated | stacked similarly, and obtained the 4-layer copper clad board. This periphery was cut and removed to obtain a size of 300 × 300 mm.
Using a standard method, a hole with a hole diameter of 250 μm is drilled with a mechanical drill, copper plating is performed after desmearing, and a reference mark for hole drilling is formed on the circuit and the four corners of the peripheral end by copper foil using a conventional method. Prepared in mmφ, and subjected to black copper oxide treatment, then prepreg C of size 250x300mm and 12μ
An m-electrode copper foil was placed and similarly laminated and molded to form a six-layer copper-clad board. The fiducial mark was not covered by the resin flow. After the desmear treatment, a copper plating of 15 μm was adhered. The copper foil where this blind via hole is to be drilled is etched away with a diameter of 100 μm, the fiducial mark is read with a CCD camera, and the copper foil of the multilayer board is etched and removed. Via holes were formed. After desmearing, after applying copper plating of 15 μm, lands for solder balls are formed, and at least the semiconductor chip mounting portion, bonding pad portions, and solder ball land portions are covered with a plating resist, and nickel and gold plating are applied. To make a printed wiring board. In this drilling process, the reference mark can be read immediately after lamination molding without grinding the copper foil and insulating layer on the reference mark for drilling formed on the inner layer plate. It is clear that it is excellent.

Example 2 300 parts of an epoxy resin (trade name: Epicoat 1001, manufactured by 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 cloth having a thickness of 100 μm, dried, gelled for 150 seconds, prepreg H having a glass cloth content of 48% by weight, and impregnated in a glass cloth having a thickness of 50 μm, and dried to be gelled for 170 minutes. In seconds, a prepreg I having a glass cloth content of 31% by weight was prepared.

Using one prepreg H, 35 μm up and down
m electrolytic copper foil was placed, laminated and formed at 190 ° C., 20 kgf / cm ² and 30 mmHg, and cut to obtain a 500 × 500 mm double-sided copper-clad laminate. Circuits were formed on the front and back of this board, fiducial marks were made at the four corners, and black copper oxide treatment was applied.
One prepreg I of 0x500 mm was placed on each sheet, and an electrolytic copper foil having a thickness of 12 µm was laminated on both outer sides of the prepreg I, and similarly laminated and molded to form a four-layer multilayer board J. The fiducial mark was not covered with the flowing resin. Then, the surface copper foil of this four-layer plate was
Etching was removed at μm, the reference mark was read with a CCD camera, and two shots were irradiated at 13 mJ to make a blind via hole. A desmear treatment was performed with an aqueous solution of potassium permanganate in the same manner as in Example 1, copper plating was performed in the same manner, and a printed wiring board was similarly formed. In this drilling process, the reference mark can be read immediately after lamination molding without grinding the copper foil and insulating layer on the reference mark for drilling formed on the inner layer plate. It is clear that it is excellent.

Comparative Example 1 In Example 2, the same size of the inner layer plate and the prepreg was laminated and molded. This is because there is a resin layer and copper foil on the fiducial mark.
I read the fiducial mark with the D camera and made a hole,
The productivity was greatly reduced as compared with the embodiment.

[0027]

According to the present invention, a carbon dioxide laser drilling reference mark is formed at the end of the surface of the inner layer copper foil of the multilayer copper clad board, and the lamination material is formed so as not to cover the reference mark at this end with the laminating material. This protruding reference mark is read by a CCD camera, and a carbon dioxide laser is irradiated from above on the multilayer copper-clad board whose surface copper foil has been processed and removed to make blind via holes, which is excellent in mass productivity and workability. In addition, a blind via hole for a printed wiring board was formed at a low cost.

[Brief description of the drawings]

FIG. 1 shows the first half of a processing step of a second embodiment. (1) Configuration, (2)
Four-layer copper clad laminate formed, (3) Surface copper foil at the position where blind via holes are formed is removed by etching, (4) CCD camera is read, and holes are formed with a carbon dioxide laser.

FIG. 2 shows the second half of the processing step of the second embodiment. (5) Desmear treatment and copper plating, (6) circuit formation.

FIG. 3 shows the first half of a conventional carbon dioxide laser drilling and copper plating process of the multilayer copper-clad board of Comparative Example 1. (1) Configuration,
(2) Four-layer copper clad laminate formed, (3) Surface copper foil at the position where blind via holes are formed is removed by etching, (4) Counter mark spotting, (5) CCD camera, read with a carbon dioxide laser Drilling holes.

FIG. 4 shows the second half of the conventional carbon dioxide laser drilling and copper plating process of the multilayer copper-clad board of Comparative Example 1. (5) Desmear treatment and copper plating, (6) circuit formation.

[Explanation of symbols]

a Four-layer board outer layer copper foil b Pre-preg C c Four-layer board inner layer circuit d Reference mark regulated at end of inner layer board e CCD camera f Blind via hole drilled by carbon dioxide gas laser g Copper-plated blind via hole Part h Surface copper foil removed by etching i External copper foil and insulating layer are ground by counterbore to expose inner layer fiducial marks

Claims (1)

[Claims] 1. A multi-layer copper-clad board that forms a blind via hole by irradiating a part of a copper foil in advance with a carbon dioxide gas laser and then irradiating the part with a carbon dioxide gas laser. It is formed at the end of the inner layer plate, and the reference hole of this inner layer plate is formed in a range that is not covered with the resin that has flowed when it is multilayered, and this multilayer mark is read by a CCD camera after multilayering. Multilayer copper clad board suitable for mass production processing of carbon dioxide laser drilling characterized by performing drilling.