JP2001196712A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-density printed wiring board superior in surface smoothness and homogeneity at a hole wall, etc. SOLUTION: A glass fiber nonwoven fabric is used as a base material which comprises flat glass fiber by 90 wt. or more, having flatness of 3.1/1-5/1, a cross-sectional area being 90-98% of the area of the rectangle circumscribing the glass fiber cross section, and a reduced fiber diameter being 5-17 μm, while the amount of binder being 3-8 wt.%. A resin composition, where the flat glass fiber powder having those characteristics is blended in a thermo-setting resin composition by 10-80 wt.%, is impregnated and dried to provide a prepreg, which is used by at least one layer, preferred as a surface layer, providing a copper-plated plate comprising a copper layer by at least one layer. At the opening of a small hole of aperture 80-150 μm, a drilling assistance layer is formed on a copper foil, which is directly irradiated with high-output carbon dioxide gas laser from above to remove the copper foil, forming a through-hole and/or blind via hole. Thus, a printed wiring board is manufactured which is superior in surface smoothness, drilling characteristics with carbon dioxide gas laser, workability, and reliability in hole connection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board using at least one outermost layer of a novel glass nonwoven fabric. More specifically, the present invention relates to a printed wiring board capable of forming a small-diameter hole, forming a fine circuit on the surface, and having a high density. This high-density printed wiring board is mainly used for small and new semiconductor plastic packages and the like.

[0002]

2. Description of the Related Art Conventionally, high-density glass cloth-based printed wiring boards used for semiconductor plastic packages, etc.
Glass woven fabric was used. This glass woven substrate printed wiring board has large irregularities in the hole walls due to the difference in the ease of drilling between the glass woven fabric and the resin layer when small holes are drilled with a carbon dioxide laser. Problem with
In addition, the surface irregularities are relatively large, and there is a problem in forming a fine circuit. Conventionally, a through hole for a through hole is drilled. In recent years, the diameter of drills has become increasingly smaller, and the hole diameter has become 150 μm or less.When drilling such small diameter holes, the drill diameter is small, so the drill bends, breaks, and the processing speed is slow when drilling. However, there are problems such as productivity and reliability.

Further, a hole of the same size is formed in a copper foil on the front and back sides in advance using a negative film by a predetermined method, and a similar hole is formed in the inner layer copper foil by etching in advance. If a carbon dioxide laser is used to form a through-hole that penetrates the front and back, the gap between the inner copper foil and the top and bottom holes will shift, resulting in poor connection and inability to form front and back lands. There were drawbacks.

[0004]

DISCLOSURE OF THE INVENTION The present invention is directed to a copper-clad suitable for drilling small-diameter holes, comprising a novel glass fiber nonwoven fabric and a thermosetting resin composition containing the glass fiber powder, which significantly improve the above-mentioned disadvantages. Provided is a high-density printed wiring board using a laminated board.

[0005]

As a result of various studies, the present inventors have found that the above problem can be solved by using a glass nonwoven fabric having a specific shape, that is, a flat glass nonwoven fabric having a specific shape. The invention has been reached. The present invention is a glass fiber having a flat cross section, a flattening ratio expressed by a ratio of a long diameter / short diameter of the cross section being 3.1 / 1 to 5/1, and a cross section having a rectangular shape circumscribing the glass fiber cross section. 90-98% of area
Containing at least 90% by weight of flat glass fibers having a converted fiber diameter of 5 to 17 μm (FIG. 1), and having a binder amount of 3 to
Provided is a printed wiring board using a copper-clad laminate for a printed wiring board in a form in which at least one layer, preferably a surface layer, of a prepreg containing 8% by weight of a glass fiber nonwoven fabric as a base material is used. This prepreg is obtained by blending 10 to 80% by weight of glass fiber powder having the above-mentioned characteristics in the flatness, cross-sectional area and reduced fiber diameter in a thermosetting resin composition. The copper-clad laminate is prepared by laminating under pressure. The printed wiring board obtained by using this is excellent in surface smoothness, warpage and the like.

[0006] The printed wiring board of the present invention is suitable for a method for making a small-diameter hole described below. As a method for drilling a small-diameter hole, a carbon dioxide gas laser drilling auxiliary layer is preferably arranged on the surface of the copper-clad laminate, and a high-energy carbon dioxide laser is pulsed from above to generate a predetermined number of shots. Irradiation to form through holes and / or blind via holes. The hole shape of the obtained through hole and brand via hole is good,
Since the glass fiber powder is more uniformly dispersed in the resin than the glass fiber alone, the pore wall has a uniform unevenness and the like, and a material having excellent hole connection reliability is obtained.

In the case of drilling holes having a small diameter of about 100 μm, it is preferable to drill holes using a carbon dioxide gas laser. In this case, the copper foil at the locations where the holes are to be drilled is removed in advance by irradiation with low-energy carbon dioxide laser energy. It is also possible to form a blind via hole by forming, but preferably, an auxiliary layer for drilling is formed on the copper foil of the copper-clad laminate, and an energy sufficient to process the copper foil from above is formed. By directly irradiating a carbon dioxide gas laser, a through hole and / or a blind via hole is formed, and a high-density printed wiring board is formed using the hole. This drilling method is excellent in workability, in a multilayer board, the dimensional shrinkage of the inner layer is automatically corrected, the processing speed is much faster than mechanical drilling, and the connection reliability of the obtained small diameter hole is improved. Which is a significant improvement over the conventional drilling method.

In order to form a circuit of higher density, the copper burrs generated around the holes are dissolved and removed, and simultaneously the copper foil on the front and back is partially dissolved and removed in the thickness direction. The total thickness of the copper foil can be kept thin, and a high-density printed wiring board can be produced.

The thermosetting resin used for the multilayer copper-clad board is preferably obtained by using a polyfunctional cyanate compound and a resin composition containing the cyanate ester prepolymer as an essential component. The obtained multilayer printed wiring board has excellent heat resistance, moisture resistance and heat resistance after moisture absorption.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a glass fiber having a flat cross section and a flatness expressed by a ratio of a major axis / a minor axis of the section.
3.1 / 1 to 5/1, the cross-sectional area is 90 to 98% of the rectangular area circumscribing the glass fiber, and the converted fiber diameter is 5 to 7
Using a glass fiber non-woven fabric base material containing 90% by weight or more of flat glass fibers of μm and having a binder amount of 3 to 8% by weight, as a thermosetting resin composition, a powder of the above glass fibers in a resin. A printed wiring board is prepared using a prepreg containing 10 to 80% by weight of a body and a glass-clad base thermosetting resin copper-clad board using at least one layer. The method for forming a small diameter hole is preferably such that a carbon dioxide gas laser drilling auxiliary layer is disposed on the surface layer, and a carbon dioxide gas laser having sufficient energy to process the copper foil is irradiated from above, and a small diameter penetration hole is formed. Form holes and / or blind via holes. A printed wiring board, a multilayer printed wiring board, preferably a build-up multilayer printed wiring board is formed by using the perforated copper-clad laminate.

In the present invention, the flat glass fiber is defined as having a flatness of
3.1 / 1 to 5/1, preferably 3.5 / 1 to 4.5 / 1. If the oblateness is less than the lower limit of the above range, the short diameter is large, so the thickness of the nonwoven fabric is reduced, and the effect of increasing the glass fiber content in the laminate is not sufficient. Fibers are difficult to produce, and the speed of impregnation of the resin of the varnish is also slow, which tends to result in impregnation failure.

Further, the cross-sectional area of the flat glass fiber used in the present invention is 90% of the rectangular area circumscribing the cross-section of the glass fiber.
~ 98%. That is, the shape is almost rectangular. By using this fiber and making paper using 3 to 8% by weight of a binder, the fibers are overlapped with the flat surface up and down, the thickness can be reduced, and the surface smoothness when laminated and formed is excellent Is obtained. The glass fiber nonwoven fabric of the present invention is used as flat glass fiber alone, or is made using a glass fiber having a partially circular cross section. As the composition of the flat glass fibers used in the present invention, those which can produce flat glass fibers, such as E glass, T glass, and D glass, can be used.

The glass nonwoven fabric of the present invention is impregnated with a varnish made of a thermosetting resin composition and dried to prepare a B-stage prepreg, which is used for building up a multilayer board. The resin content is generally 40-70 for the inner layer plate.
% By weight. Also, for lamination, generally the resin amount is 70
To 85% by weight. The flat glass fiber powder is a powder of the above glass fiber, and the cut length is not particularly limited, but preferably has an average length of 5 to 30 μm. This glass fiber powder is put into the thermosetting resin composition and is uniformly dispersed. The amount used is 10 to 80% by weight in the thermosetting resin composition
%, Preferably 20 to 70% by weight. The printed wiring board of the present invention is a printed wiring board prepared using a copper-clad laminate having at least one copper foil layer, and includes a multilayer printed wiring board, a build-up printed wiring board, and the like. In a multilayer copper-clad laminate, a prepreg obtained by using a glass woven fabric or a glass nonwoven fabric substrate for an inner layer plate, impregnating a thermosetting resin composition in which flat glass fiber powder is blended with the nonwoven fabric substrate, and drying. Can be used as a method for forming a through hole and / or a blind via hole. For example, drilling by a laser, drilling by a mechanical drill, and the like can be mentioned. An excimer laser and a YAG laser are used for a pore diameter of 25 μm or more and less than 80 μm, a carbon dioxide gas laser is suitably used for a pore diameter of 80 μm or more and 180 μm or less, and a mechanical drilling is preferably used for a hole having a pore diameter of more than 180 μm. Although the wavelength is not particularly limited, a wavelength and energy capable of processing the copper foil are selected and used.

In particular, in the case of blind via drilling by a carbon dioxide laser, a conventional method of irradiating a low-energy carbon dioxide laser energy by removing the surface copper foil by etching beforehand can be used. Is a problem, and it is difficult to form a fine circuit. For this purpose, the surface of the copper foil is preferably subjected to metal oxide treatment or treatment with a chemical solution. Alternatively, a coating in which a metal compound powder having a melting point of 900 ° C. or more and a binding energy of 300 kJ / mol or more, an organic substance and an organic substance, preferably a water-soluble resin composition, are mixed as an auxiliary layer on the surface copper foil. Is applied to form a coating, or on one side of a thermoplastic film, a hole-forming auxiliary obtained by adhering a resin composition such that the total thickness including the thickness of the thermoplastic film is 30 to 200 μm. The sheet is placed, preferably laminated and adhered to the copper foil surface, and directly irradiated with a carbon dioxide gas laser from above the auxiliary layer, and the copper foil is processed and removed, thereby forming through holes and / or blind via holes. Holes can be formed.
On the copper-clad multilayer board, laminate the sheet under heat and pressure, with the surface with the resin adhered to the copper foil side, or wet the surface of the resin 3 μm or less in advance with moisture, and then add it at room temperature. By laminating the front and back sides under pressure, the adhesion to the copper foil surface becomes good, and a good hole shape can be obtained.
As the metal oxide treatment to be formed on the copper foil surface, a generally known metal oxide treatment can be used. Specific examples include black copper oxide treatment and MM treatment (MacDermid). Further, as the chemical solution treatment, CZ treatment (Mec) or the like is preferably used.

After drilling, burrs of the copper foil on the front and back and the inner layer are generated. Therefore, an etching solution is sprayed or sucked to dissolve and remove the burrs of the copper foil generated in the holes through the holes.
At the same time, when the copper foil is thick, a part of the thickness of the copper foil on the front and back is dissolved and removed, and the thickness is preferably 2 to 7 μm, more preferably 3 to 5 μm.
m. When the copper foil is thin from the beginning, only the burrs are etched away while leaving the auxiliary layers formed on the front and back sides, and then the auxiliary layers are removed. Then, the entire board is copper-plated by a standard method, and a circuit is formed to form a printed wiring board.

The copper clad board used in the present invention has at least 3
It is a multilayer copper-clad board having more than one copper layer, and the inner layer board uses a glass woven fabric or a non-woven fabric substrate, and preferably contains the flat glass fiber powder in a thermosetting resin composition. A circuit is formed on the copper-clad board obtained as described above. A prepreg obtained by performing a surface treatment as necessary and using at least one flat glass fiber base material, impregnating a resin composition containing the flat glass fiber powder in a thermosetting resin, and drying is arranged. And put copper foil on the outside, heat, pressurize,
Preferably, lamination molding is performed under vacuum. Also, when creating a high-density circuit, the surface copper foil should be thin from the beginning, or a thick copper foil should be laminated and molded, and then the surface copper foil should be etched down to 2 to 7 μm with an etchant. Thinner can be used. When a thin copper foil is used from the beginning, a copper foil with a carrier such as copper or aluminum is mainly used.

As the resin of the thermosetting resin composition for a 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 the 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, JP-B-41-1928 and JP-B-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. A generally known polyimide resin 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 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 auxiliary layer used in the present invention has a melting point of 900.
As the metal compound having a binding energy of 300 kJ / mol or more at a temperature of not less than ° C., generally known compounds can be used. Specifically, as the oxide, titanias such as titanium oxide,
Magnesia such as magnesium oxide, nickel oxide such as nickel oxide, manganese dioxide, zinc oxide such as zinc oxide, silicon dioxide, aluminum oxide, rare earth oxide,
Cobalt oxides such as cobalt oxide, tin oxides such as tin oxide, and tungsten oxides such as tungsten oxide. Examples of the non-oxide include generally known ones such as boron nitride, silicon nitride, titanium nitride, aluminum nitride, barium sulfate, and rare earth oxysulfide. In addition, various glass powders which are a mixture of metal oxide powders can be used. Carbon powder and metal powder such as silver, copper, iron and nickel can also be used, and these are used alone or in combination of two or more. The average particle size is not particularly limited, but is preferably 1 μm or less.

Since the molecules are dissociated or melted and scattered by the irradiation of the carbon dioxide laser, the metal adheres to the hole walls and the like, and does not adversely affect the semiconductor chip and the hole wall adhesion. preferable. Since Na, K, Cl ions and the like particularly adversely affect the reliability of the semiconductor, those containing these components are not suitable. The compounding amount is from 3 to 97 vol%, preferably from 5 to 95 vol%, and is mixed with the resin and uniformly dispersed.

The resin of the auxiliary layer is not particularly limited.
Generally known materials can be used, but if removed after drilling, they may adhere to the copper foil surface, and from the viewpoint of subsequent dissolution and removal, water-soluble resins are preferred. In particular,
Water-soluble polyester resins, polyether resins, polyvinyl alcohol, starch and the like are used. Also in this case, the various additives described above can be added.

The method of preparing the composition comprising the metal compound powder and the resin, and the method of forming a sheet are not particularly limited, but they are kneaded at a high temperature without a solvent using a kneader or the like, and extruded into a sheet on a thermoplastic film. The method of adhesion, the acidic resin is dissolved in a solvent, the above powder is added thereto, and the mixture is uniformly stirred and mixed. The mixture is used and applied as a paint to a copper foil surface and dried to form a coating film or a thermoplastic resin. A generally known method such as a method of applying a film on a film and drying to form a film can be used. The thickness is not particularly limited, but when applied, the thickness of the coating is preferably 30 to 100 μm, and when applied to a film to form a coating with a film, the total thickness is preferably 30 to 100 μm.
It should be 200 μm.

When laminating the copper foil surface under heating and pressure, the coating resin layer is directed to the copper foil surface, and the temperature is generally 40 to 150 ° C., preferably 60 to 120 ° C., and the linear pressure is generally
Laminate at a pressure of 0.5-20 kg, preferably 1-10 kg,
The resin layer is melted and brought into close contact with the copper foil surface. The selection of the temperature depends on the melting point of the water-soluble resin to be used, and also depends on the linear pressure and the laminating speed. In general, lamination is performed at a temperature higher by 5 to 20 ° C. than the melting point of the resin. The metal oxide treatment is not particularly limited, for example, black copper oxide treatment, MM
Processing (MacDermid). Examples of the chemical treatment include generally known treatments such as CZ treatment (Mec).

The substrate-reinforced copper-clad board is first impregnated with a thermosetting resin composition and dried to form a B stage,
Create a prepreg. Next, a predetermined number of the prepregs are stacked, a copper foil is arranged on at least one side, and laminated under heat and pressure to form a copper-clad laminate. Further, a multi-layer board prepared by using this can also be used. The thickness of the outer layer copper foil is
Preferably, it is 3 to 12 μm, and the inner layer is 9 to 35 μm. The type of the copper foil is not particularly limited, but an electrolytic copper foil having a double-sided roughened foil can be used for the inner layer. Electrolytic copper foil is preferred for both the inner and outer layers.

The method of the present invention for partially removing the copper burrs generated in the holes and the copper foil of the surface layer in the thickness direction by etching is not particularly limited. For example, JP-A Nos. 02-22887 and 02-22887 disclose the method.
-22896, 02-25089, 02-25090, 02-59337, 02-6
0189, 02-166789, 03-25995, 03-60183, 03-94
491, 04-199592 and 04-263488,
It is based on a method of dissolving and removing a metal surface with a chemical (referred to as a SUEP method). Etching rate is generally 0.02-1.0 μm
Per second. Further, in the case of removing the inner layer copper foil burr by etching, the spray angle and pressure of the etching solution are appropriately selected. A method of removing burrs by suction may also be used.

The energy of the carbon dioxide laser is preferably selected from 20 to 60 mJ / pulse. A high-output energy carbon dioxide laser beam is irradiated directly from above the auxiliary layer to process the copper foil to form holes. Do. As the carbon dioxide laser, a wavelength of 9.3 to 10.6 μm in an infrared wavelength range is generally used.
The output is not particularly limited, but preferably, pulse oscillation is performed at 20 to 60 mJ / pulse, and a necessary pulse (shot) is irradiated to process the copper foil and the insulating layer to make holes. When drilling through-holes and / or blind via holes, 20-60 from beginning to end
Either a method of irradiating energy selected from mJ / pulse or a method of processing an insulating layer by increasing or decreasing the energy after processing a copper foil can be used.

A metal plate can be simply disposed on the back surface of the copper-clad plate to prevent the laser machine table from being damaged by the laser when the hole penetrates. A resin layer to which at least a part is adhered is adhered to a copper foil on the back surface of the copper clad board, and a through hole is formed. When the front and back copper foils are thin, copper foil burrs generated around the holes are dissolved and removed with an etchant while leaving the front and back auxiliary layers after drilling. Also, when the front and back copper foil is thick, the resin layer is dissolved and removed first after drilling the through hole, and then the etching liquid is sprayed or sucked to partially dissolve and remove the front and back copper foil in a plane. By removing the inner layer copper burrs and setting the thickness of the surface copper foil to 2 to 7 μm, it is possible to form a fine circuit in the formation of a copper-plated circuit, and to create a high-density printed wiring board Can be. The latter is preferred from the viewpoint of removing surface dirt and foreign matter. The same applies to the case of forming a blind via hole.

In most cases, a resin layer of about 1 μm is left on the surface of the copper foil surface on the surface of the inner surface of the processed hole where the resin of the copper foil 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. 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, but the inside of the hole can be partially filled with copper plating, preferably 90% or more.

[0033]

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.)
400 parts, cresol novolak type epoxy resin (trade name: ESCN-220F, manufactured by Sumitomo Chemical Co., Ltd.) 600 parts, epoxy silane coupling agent (trade name: A167, Nippon Yunika Co., Ltd.) 4
0 parts were added and uniformly dissolved and mixed. Further, 0.4 part of zinc octylate was added as a catalyst, and the mixture was dissolved and mixed.
/ 1, area ratio is 92%, converted fiber diameter is 10μm, average length is 12
μm flat glass fiber having a length of 1 to 15 μm, an average length of 7.3 μm, 4,000 parts of fiber powder, and black pigment 8
A varnish A having the resin composition to which the varnish was added was obtained. This varnish has a thickness of 100
μm glass woven cloth and dried at 150 ℃, gel time
(at 170 ° C.) 115 seconds, a prepreg B having the resin composition content of 50% by weight was prepared. The flatness ratio is 4/1 and the area ratio is 92%
In, in terms of fiber diameter 10 [mu] m, dispersed in length polyethylene oxide dispersed solution in high flat glass fiber of 13 mm, a thickness of 62 .mu.m, epoxy resin emulsion nonwoven fabric basis weight was papermaking such that 20 g / m ² Then, an adhesive solution using an epoxy silane coupling agent as a silane coupling agent was prepared, adhered at 4% by weight, and dried at 150 ° C. to obtain a nonwoven fabric. Using this, the varnish A was impregnated, dried and adhered to a resin amount of 80% by weight to prepare a prepreg C having a gel time of 95 seconds.

Electrolytic copper foil having a thickness of 12 μm was placed above and below the two prepregs B and laminated and molded at 200 ° C., 20 kgf / cm ² , and a vacuum of 30 mmHg or less for 2 hours to form a double-sided copper-clad laminate D. Obtained. An inner layer circuit is formed, and the surface thereof is subjected to CZ treatment (MEC Corporation), and one of the prepregs C is disposed on both outer sides thereof,
Further, an electrolytic copper foil having a thickness of 12 μm was disposed thereon, and was similarly laminated and molded to obtain a four-layer plate E.

On the other hand, MgO (54%), SiO ₂
To a varnish prepared by dissolving a water-soluble polyester resin in a mixed solvent of water and methanol, to 800 parts of a mixture powder (average particle size: 0.9 μm) consisting of
Got F. This was applied to one side of a 50 μm-thick polyethylene terephthalate so as to have a thickness of 20 μm.
After drying for minutes, an auxiliary material layer having a metal compound content of 40 vol% was prepared, and an auxiliary material G was obtained. On the back surface, the varnish F was applied to one surface of an aluminum foil having a thickness of 50 μm, and dried similarly to prepare a backup sheet H having a coating film having a thickness of 20 μm. The auxiliary material G is arranged on the front surface of the four-layer board E, the backup sheet H is arranged on the back side, and the resin layer is arranged so as to face the copper foil side. Laminated. From above, using a carbon dioxide laser machine, a hole with a diameter of 100 μm is directly shot in a 50 mm square with a carbon dioxide laser, with one shot at an output of 25 mJ / pulse, then one shot at an output of 10 mJ / pulse, and one shot at the end, and finally 15 mJ / pulse
One pulse irradiation was performed to form a blind via hole having a hole diameter of 100 μm. Also, one shot at 30 mJ / pulse, 2 shots
By irradiating 5 shots at 5 mJ / pulse, a through hole with a hole diameter of 120 μm was made.

After the auxiliary material layers of the front and back layers are peeled off and put into a plasma device for processing, a SUEP solution is sprayed at a high speed to dissolve and remove burrs on the front and back and the inner layer, and at the same time, the copper foil of the front layer is reduced to 4 μm. Dissolved. After desmearing, deposit copper plating 15μm, and then use the existing method (line / line).
Space = 50/50 μm). After forming a circuit on the front and back sides and performing CZ treatment, one prepreg C was similarly placed on each side, and a 12 μm electrolytic copper foil was placed on the outside of the prepreg C, and laminated and formed in the same manner to form a six-layer plate. Similarly, a drilling assisting material was arranged on the front and back sides and bonded with a hot roll at 100 ° C., and then a blind via hole was drilled by pulse oscillation of a carbon dioxide gas laser under the same conditions, and a through hole was drilled. Thereafter, the auxiliary material on the front and back was peeled off, and the thickness of the front and back was dissolved and removed to 4 μm by SUEP, and the copper foil burr was also dissolved and removed at the same time. Circuits such as pads for solder balls were formed on the front and back surfaces, and at least the semiconductor chip, bonding pads, and solder ball pads were covered with a plating resist, and nickel and gold plating were applied to produce printed wiring boards. Table 1 shows the evaluation results of the printed wiring board.

Example 2 Epoxy resin (trade name: Epicoat 1001, Yuka Shell Epoxy Co., Ltd.), 300 parts, 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 and 20 parts of the epoxysilane coupling agent of Example 1 were added, and these were dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide. Ratio 94%, fiber length 0.7
Varnish I was prepared by mixing 300 parts of flat fiber powder having a fiber length of ２３23 μm and an average fiber length of 11 μm. This varnish was formed into a non-woven fabric in the same manner as in Example 1 using a fiber having an aspect ratio of 4/1, an area ratio of 94%, a converted fiber diameter of 10 μm, and a fiber length of 13 mm, and a binder having a solid content of 7% by weight. And dried in the same manner to obtain a nonwoven fabric having a basis weight of 21 g / m ² . Using this glass fiber non-woven fabric, impregnated with varnish I and dried, gel time 120 seconds,
Prepreg J having a resin amount of 50% by weight, gelling time of 110 seconds, and prepreg K having a resin composition amount of 79% by weight were obtained.

Using the four prepregs J, 12
A μm 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 L (FIG. 2 (1)). Circuits are formed on the front and back of this board, and MM processing (MacDerm
id company), put one prepreg K on the outside, put 3μm electrolytic copper foil with 35μm copper foil carrier on the outside, peel off the 35μm copper foil carrier after laminating similarly, A four-layer plate M was prepared (FIG. 2 (2)).

On both sides, a mixture of the transparent acrylic acid resin having an acid value of 100 mgKOH / g and the metal compound of Example 1 was applied, dried at 120 ° C. for 20 minutes, and dried to a thickness of 30 μm.
A coating of 65 vol% of the metal compound was formed. Thickness 50 on this back
Place a 1 μm aluminum foil, irradiate 1 shot at 30 mJ / pulse and 4 shots at 28 mJ / pulse as in Example 1, and make a 120 μm through hole, and 1 shot at 20 mJ / pulse, 10 mJ / pulse. One shot and then one shot at 15 mJ / pulse were applied to make a blind via hole with a hole diameter of 100 μm (FIG. 2 (3)). Copper foil burrs remaining around the hole were dissolved and removed with an acidic etching solution, leaving the front and back auxiliary resin layers, and then the front and back auxiliary layers were removed by stripping. Perform desmear treatment with aqueous potassium permanganate solution (Fig. 2
(4)) Copper plating was performed in the same manner as in Example 1 (FIG. 3).
(5)) Similarly, a printed wiring board was formed (FIG. 3).
(6)). Table 1 shows the evaluation results.

Comparative Example 1 Using the multilayer copper-clad board of Example 1, holes were similarly formed with a carbon dioxide gas laser without attaching anything to the surface, but no holes were formed.

Comparative Example 2 In Example 2, the surface to be irradiated with a carbon dioxide gas laser was coated on the copper foil surface with black magic, and the hole was drilled in the same manner, but no hole was formed.

Comparative Example 3 Glass fibers having an elliptical approximate cross-section with an aspect ratio of 4/1 and an area ratio of 75%, a converted fiber diameter of 10 μm, and a length of 13 mm were used. The prepregs N and O were prepared in the same manner as in Example 1 except that a nonwoven fabric impregnated so that the content of the prepreg was 8% was used, and the flat glass fiber powder was not used. Using this, lamination molding was performed in the same manner as in Example 1, and holes were similarly drilled to obtain a printed wiring board. SUEP was not implemented. Table 1 shows the evaluation results.

Comparative Example 4 In Example 2, Epicoat 5045 was used as an epoxy resin.
Using a glass woven fabric of # 1080 type (weight: 48 g / m ² ) using circular fibers as glass fibers, and using varnish I, a varnish containing no flat glass powder and a resin amount of 70% by weight were used. The prepreg P having a gelation time of 116 seconds was obtained in the same manner as in Example 2, except that the prepreg was impregnated and dried. Further, a glass fiber woven fabric having a thickness of 100 μm was impregnated and dried to prepare a prepreg Q having a gelation time of 122 seconds and a resin amount of 45% by weight. Using two prepregs Q, 175 ℃, 20kg
Laminate molding was performed at f / cm ² for 2 hours to prepare a double-sided copper-clad laminate R. After forming a circuit on both sides and subjecting it to black copper oxide treatment, one prepreg P was placed on each side and laminated and formed under the same conditions to obtain a four-layer board S. Use this with a drill diameter of 150
A through hole was drilled at 100,000 rpm with a μm mechanical drill. A desmear treatment was performed once without performing the SUEP treatment, and thereafter, copper plating was performed by a normal method to prepare a printed wiring board. Table 1 shows the evaluation results.

Comparative Example 5 The procedure of Example 2 was repeated, except that a varnish containing no flat glass fiber powder was used.
Second, prepreg T with 55% by weight of resin, gel time 97 seconds,
A prepreg U having a resin amount of 70% by weight was obtained. Above prepreg T
4 was used and laminated and molded in the same manner as in Example 2 to form a double-sided copper-clad plate V (FIG. 4 (1). Using this, the copper foil at the location of the through hole in the inner layer had a hole diameter of 100 μm). After etching and removing the upper and lower copper foils to form a circuit, the copper foil surface is treated with black copper oxide, one prepreg U is placed on the outside, and 12 μm electrolytic copper foil is placed on the outside, Similarly, a four-layer plate was formed by lamination molding.
900 holes with a diameter of 100 μm are placed at the position of the surface where the through hole is to be formed.
Pieces and copper foil were etched and opened. Similarly, 900 holes having a hole diameter of 100 μm were formed in the same position on the back surface (FIG. 4B).
Sixty shots of a total of 63,000 holes of 900 patterns were applied from the surface with a carbon dioxide gas laser at an output of 15 mJ / pulse for 6 shots to form through holes (FIG. 4C). By operating, without performing the SUEP processing, a desmear processing was performed once, a copper plating was performed by 15 μm (FIG. 4 (4), a circuit was formed on both sides, and a printed wiring board was similarly prepared. It is shown in FIG.

[0046] EXAMPLE compare 1 Item implementation example ratios in Table 1 2 3 4 5 top- land copper foil 0 0 0 0 gap between 27 ([mu] m) deviation of hole position of the inner layer 0 0 0 0 39 ([mu] m) hole Wall unevenness Almost same Left A little Almost N / A N / A N / A Large Pattern break and 0/200 0/200 57/200 55/200 54/100 Short (piece) Glass transition temperature 235 160 160 139 160 (℃) Through-hole heat cycle test (%) 100 cycles 1.3 1.5 1.5 1.6 2.9 300 cycles 1.6 1.8 1.8 2.3 4.9 500 cycles 1.9 2.2 2.4 5.8 27.7 drilling time (min) 19 16 over 630 over migration resistance (HAST) (Omega) normal 3x10 ¹¹ overー 1x10 ¹¹ー 200hrs.8x10 ⁸ <10 ⁸ 500hrs.5x10 ⁸ー 700hrs.4x10 ⁸ 1000hrs.3x10 ⁸ Surface smoothness 0.5 0.5 1.9 2.3 ー

<Measurement method> 1) Deviation of front and back hole positions and drilling time 70 blocks (63,000 total holes) were prepared in a 250 mm square work piece with 900 holes / block having a hole diameter of 100 μm.
The time required to drill 63,000 holes in one copper clad plate by drilling holes with a carbon dioxide laser and a mechanical drill,
The maximum value of the deviation between the copper foil for front and back lands and the hole and the deviation of the inner layer copper foil was shown. 2) Hole wall irregularities The hole cross section was observed. 3) Circuit pattern breakage and short-circuit In the examples and comparative examples, a plate without holes was prepared in the same manner, and a comb pattern of line / space = 50/50 m was prepared. The pattern was visually observed, and the total of the cut pattern and the short-circuited pattern was shown in the molecule. 4) Glass transition temperature Measured by the DMA method. 5) 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. 6) Migration resistance (HAST) A total of 50 holes are connected without passing one through hole with a hole diameter of 100 μm or 150 μm (mechanical drill) alternately.
Make a total of 100 sets so that they are parallel
After a predetermined time treatment at 30 ° C., 85% RH, and 1.8 VDC, the samples were taken out and the insulation resistance between through holes arranged in parallel was measured. 8) Surface smoothness Measured with a surface roughness meter.

[0048]

According to the present invention, the cross section is flat, and the oblateness expressed by the major axis / minor axis of the cross section is 3.1 / 1 to 5/1, and the cross sectional area is
90-98% of the rectangular area circumscribing the glass fiber cross section
The converted fiber diameter is 5 to 17 μm containing flat glass fiber of 90% by weight or more, and the amount of binder is 3 to 8% by weight using a glass fiber nonwoven fabric as a base material, having the above properties in the resin The prepreg obtained by impregnating and drying the thermosetting resin composition containing the flat glass fiber powder is dried at least.
Provided is a printed wiring board obtained using a copper-clad laminate or a multilayer copper-clad laminate obtained by laminating and forming one or more layers, preferably a surface layer. The (multi-layer) copper-clad laminate has excellent surface smoothness, can reduce the thickness of the glass layer, and can increase the density of the glass fiber,
A uniform hole wall is obtained by laser drilling. In drilling, it is suitable for drilling with a high-energy carbon dioxide laser. Preferably, 20-60 mJ / pulse energy is applied directly to the copper foil by forming an auxiliary layer on the copper foil surface and then irradiating the copper foil. It is possible to form a through-hole and / or a blind via hole in which a hole is formed and the hole wall has less unevenness.
Next, after etching and removing the inner and outer layer copper foil burrs protruding in the holes, perform desmear treatment as necessary, and further manufacture a printed wiring board using a copper-clad board obtained by performing copper plating, thereby penetrating. The holes do not have a gap between the holes on the front and back of the copper clad board and the land copper foil, and the processing speed can be remarkably increased as compared with the case of drilling with a mechanical drill, and the productivity can be greatly improved. In addition, by using it as a thin copper foil with a thickness of 3 to 7 μm, even in the circuit formation of the front and back copper foil obtained by plating up with subsequent copper plating, high-density printing without defects such as short circuit and pattern breakage A wiring board was produced, and a product having excellent reliability was obtained. Furthermore, by using a polyfunctional cyanate ester resin composition as the thermosetting resin composition, the resulting printed wiring board was obtained with excellent heat resistance, migration resistance, and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flat glass fiber.

FIG. 2 shows a process of drilling through holes and blind via holes by a carbon dioxide laser using the multilayer copper-clad laminate of Example 2 (3), and removing burrs by SUEP (4).

FIG. 3 shows copper plating of holes of a multilayer copper-clad laminate of Example 2 using a carbon dioxide laser (5), coating with a plating resist, nickel plating, gold plating, and solder ball bonding.
It is a process drawing of (6).

FIG. 4 is a process diagram of drilling (3) and copper plating (4) of the multilayer copper-clad laminate of Comparative Example 5 using a carbon dioxide gas laser (without SUEP).

[Explanation of symbols]

a double-sided copper-clad laminate b 4-layer copper-clad laminate c inner-layer copper foil circuit d laminated nonwoven glass substrate thermosetting resin composition layer e carbon dioxide gas laser drilling auxiliary layer f through-hole made by carbon dioxide gas laser g Via hole by carbon dioxide laser h Copper foil burr on the outer layer blind via hole generated i External layer copper foil burr on the through hole generated j Via hole after burr was removed by SUEP k Burr was removed by SUEP Through hole l Copper-plated blind via hole m Copper-plated through hole n Plating resist o Solder ball p Inner layer copper foil part with misalignment q Copper plating of through hole with poor drilling (no SUEP ) R Surface copper foil circuit s Inner copper foil burr generated by carbon dioxide laser drilling

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/46 H05K 3/46 TNF term (Reference) 4F100 AA18 AA20 AB10 AB16 AB17B AB17D AB25 AB33D AG00A AH06 AK01A AK41 AK41A AK49 AK53 AL05A AT00B BA02 BA03 BA04 BA05 BA10A BA10D CA13 DC11C DE01A DG03A DG15A DH01A EH71 EJ91 GB43 JB13A JJ03 JK15 JL00 JL01 YY00A 5E346 AA12 AA15 BB01 CC02 DD08 CC12 DD08

Claims (4)

[Claims] Claims: 1. A glass fiber having a flat cross section and a flattening ratio expressed by a ratio of the major axis to the minor axis of the cross section is 3.1 / 1 to 5/1,
The cross-sectional area is 90 to 98% of the rectangular area circumscribing the glass fiber cross section, the flat glass fiber having a converted fiber diameter of 5 to 17 μm is 90% by weight or more, and the amount of the binder is 3%.
~ 8 wt%, a glass fiber nonwoven fabric substrate having a thickness of 100 μm or less, and a flattening rate, a cross-sectional area and a converted fiber diameter of 10 to 80 wt% of a thermosetting resin blended with a glass fiber powder having the above characteristics. A prepreg comprising the composition is added at least to the outermost layer.
A printed wiring board characterized by using more than one layer. 2. The printed wiring board according to claim 1, wherein the thermosetting resin is a resin composition containing a polyfunctional cyanate ester compound and the cyanate ester prepolymer as essential components. 3. A hole for forming a printed wiring board is formed by disposing an auxiliary layer for forming a carbon dioxide gas laser on a surface of a multilayer copper-clad board using the prepreg according to claim 1; 3. The printed wiring board according to claim 1, wherein a through-hole and / or a blind via hole are formed by directly irradiating a carbon dioxide laser having sufficient energy to process the foil. 4. After the carbon dioxide gas laser drilling, the surface copper foil is partially dissolved and removed in the thickness direction with a chemical solution, and at the same time, copper foil burrs generated around the hole are dissolved and removed. The multilayer printed wiring board according to claim 1, 2 or 3.