JP2001353813A - Multiple metallic foil-covered plate suitable for holing with carbon dioxide gas laser and printed wiring board using multiple metallic foil-covered plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic foil-covered plate, using a metallic foil, in which a through hole and/or a blind via hole can be opened by directly irradiating the plate with a carbon dioxide gas laser, even when the surface of the metallic foil is rubbed and cut as well as a highly integrated printed wiring board. SOLUTION: This multiple metallic foil-covered plate with the arranged metallic foil is prepared in such a way that the shiny face of the plate consisting of a copper layer, a nickel layer or a nickel alloy layer hest suitably becomes the nickel layer or the nickel alloy layer. In addition, the shiny face is directly irradiated with the carbon dioxide gas laser of such an output selected from the range of 5-60 mJ and thus the through hole and/or the blind via hole are opened to obtain the printed wiring board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a multilayered copper and nickel or nickel alloy layer capable of forming a small diameter through hole and / or a blind via hole by directly irradiating a carbon dioxide gas laser to a metal foil surface. The present invention relates to a multiple metal foil clad board using heavy metal foil, and a printed wiring board formed by making a small diameter hole in the multiple metal foil clad board with a carbon dioxide laser. This printed wiring board is suitable for use as a small and lightweight semiconductor plastic package, motherboard or the like.

[0002]

2. Description of the Related Art Hitherto, a multi-layer metal foil multiplexed with copper has not been used as a surface metal foil in a high-density printed wiring board used for a semiconductor plastic package or the like. In drilling, the through-hole is drilled by a mechanical drill or the like. In recent years, the hole diameter has become smaller and smaller, and designs with a hole diameter of 0.15 mmφ or less have been implemented. Drilling such small diameter holes has disadvantages such as low processing speed, productivity,
There was a problem with workability 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. This process involves laminating and bonding of an etching film, exposure, development, etching, and a film peeling process, which requires time, and has a problem in workability and the like. There is a method in which a black copper oxide layer is provided on the surface of a copper foil, and a carbon dioxide laser is irradiated thereon to form a blind via hole. However, in this case, the black copper oxide layer on the surface of the copper foil was easily peeled off due to friction, and there was a problem that holes were not formed even when this portion was irradiated with a laser, and defective products were easily generated. In addition, a hole of the same size was made in advance by using a negative film on the front and back copper foils in a predetermined manner using a negative film. When trying to form a hole that penetrates the front and back with a carbon dioxide gas laser, there are gaps in the position of the inner copper foil, a gap between the upper and lower holes and the land, poor connection, and the inability to form the front and back lands was there.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and provides a metal foil-clad board using a metal foil which can be pierced by irradiating a carbon dioxide laser directly onto the metal foil, and the metal foil. An object of the present invention is to provide a high-density printed wiring board in which a small diameter through-hole and / or a blind via hole are formed by directly irradiating a carbon dioxide laser on a metal foil of a veneer.

[0004]

According to the present invention, there is provided a multi-layer metal foil in which copper and nickel or a nickel alloy layer are alternately formed as an outer layer of a metal foil clad board having a thermosetting resin composition as an insulating layer. The present invention provides a multi-layer metal foil clad board suitable for drilling by a carbon dioxide gas laser, wherein the metal foil can be drilled by direct irradiation of a carbon dioxide gas laser. Further, in the present invention, an energy carbon dioxide gas laser selected from 5 to 60 mJ is directly irradiated on the multiple metal foils of the multiple metal foil clad board to form through holes and / or blind via holes having a hole diameter of 80 to 180 μm. Provided is a printed wiring board characterized by being produced by: According to the present invention, a small-diameter through hole and / or a blind via hole can be easily formed without generating a defective product, and time for etching and removing a copper foil in advance can be saved.
This has the advantage that small holes can be efficiently created at high speed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The metal foil used for the multiple metal foil clad board of the present invention is a multiple metal foil in which copper and a nickel layer or a nickel alloy layer are multiplexed. The matte surface that adheres to the resin opposite to the shiny surface of the multi-layered metal foil irradiated with the carbon dioxide gas laser is preferably a generally known metal foil surface treatment for a metal foil clad board in order to increase the adhesion of the resin. It is preferable that it is performed. The multi-metal foil is laminated with the thermosetting resin composition layer as an insulating layer with the shiny side of the multi-metal foil facing outside, and heated or pressed continuously or discontinuously to produce a multi-metal foil clad board or a multilayer board. The multiple metal foil clad board and multilayer board thus obtained can be drilled with a small diameter without causing defective products by directly irradiating the carbon dioxide gas laser onto the multiple metal foil even if the surface slightly rubs. Is possible. After drilling, burrs are generated on the front and back and inner layers of the multiple metal foils or copper foils. In this case, burrs can be removed by mechanical polishing, but etching with a chemical is preferred from the viewpoint of dimensional change and the like. More specifically, an etching solution is sprayed or suctioned at a high pressure to pass through the hole to dissolve and remove burrs on the inner and outer layers of the multiple metal foil or copper foil. Grinding by wet blasting can also be used. Thereafter, a circuit is formed on the front and back sides using a double-sided metal foil-clad board obtained by plating up with copper plating, and a printed wiring board is formed by a standard method.

The metal foil of the multi-metal foil clad board used in the present invention forms a multi-layer of copper and nickel or a nickel alloy, and forms a through hole and / or a blind via hole of 80 to 180 μm. In addition, this is a multi-layered metal foil capable of forming holes by directly irradiating energy of 5 to 60 mJ. As the multilayer, a metal foil obtained by forming the multilayer such that the nickel or nickel alloy layer is the outermost layer (the surface of the metal foil clad plate) is preferably used. As the mat surface of the metal foil to be bonded to the resin on the side opposite to the shiny surface, a surface subjected to a generally known treatment for a copper foil plate is preferably used. For example, a material obtained by subjecting a surface of a multi-metal foil serving as a mat surface to a roughening treatment by plating with copper-cobalt-nickel and then a cobalt treatment or a cobalt-nickel plating treatment is used. The multiple metal foil surface used on the resin side has irregularities of several μm. The shiny surface of this multi-layer metal foil clad plate may or may not have irregularities, but considering the subsequent thinning treatment with a chemical solution, it is preferable that the irregularities be as small as possible. After such treatment, a generally known rust preventive treatment such as a single film treatment of a chromic acid compound or a mixed film treatment of chromium oxide and zinc and / or zinc oxide is performed to prevent discoloration and rust. Is preferred. Thereafter, a silane coupling agent treatment is performed as necessary. The thickness of the multiple metal foil is preferably 3 to 12 μm. As the inner layer plate, a multi-metal foil or a copper foil having a thickness of 9 to 35 μm is preferably used. The copper foil is not particularly limited, but a copper foil formed by electrolysis is preferably used.

[0007] The multiple metal foil clad board of the present invention has at least one
The outermost layer (the surface of the metal foil clad board) is a metal foil clad board and a multilayer board in which a layer of multiple metal foils is present. thing,
A resin alone without a reinforcing substrate can be used. However, from the viewpoint of rigidity, a glass cloth substrate is preferable.

[0008] The multi-metal foil is a multi-layer of copper and nickel or a nickel alloy, and has at least three or more layers, preferably the outermost layer (surface) of the multi-metal foil clad board.
Is a nickel or nickel alloy layer. When the copper layer of the multiple metal foil is used as the outermost layer (surface) as a shiny surface, the thickness of the copper foil on the shiny surface is preferably 3 μm or less. In this case, it is preferable for the formation of the holes that the unevenness is formed to be several μm on the surface. If the copper layer is thicker, it becomes difficult to form holes.

When a high-density circuit is formed, a thin multi-layer metal foil of the surface layer to be laminated can be used from the beginning, but preferably, a multi-layer metal foil having a thickness of 9 to 12 μm is laminated and formed. After drilling with a carbon dioxide laser or the like, the surface of the multi-layer metal foil is etched with an etchant at 2 to 7 μm, preferably 3 to 5 μm.
It is used after being thinned to μm and plated with metal, preferably copper. By doing so, a high-density printed wiring board can be produced without occurrence of a defect such as a short circuit or a broken pattern. Furthermore, the processing speed is much faster than when drilling, and the productivity is good.
What is excellent in economical efficiency can be obtained.

The single-sided or double-sided multi-layered metal foil clad of the present invention comprises:
Place the B stage sheet at the time of lamination molding and arrange multiple metal foils on the outside, or arrange multiple metal foils with B stage resin, and use a stainless steel plate on the outside, heat, pressurize, preferably under vacuum It is obtained by lamination molding. In addition, using an inner layer plate, if necessary, a chemical treatment is applied to the surface of the multi-layer metal foil or the surface of the copper foil of the inner layer plate, and a B-stage sheet and a multi-layer metal foil, or a multi-layer metal foil with a B-stage resin are arranged outside thereof, Similarly, a multilayer board is formed by lamination molding. In the case of a double-sided multiple metal foil clad board, one of the metal foils may be a copper foil. As the laminating method, a method of continuously attaching the inner layer plate to the inner layer plate under pressure with a heating roll, and then performing thermosetting may be used. At the time of this heating, each metal constituting the multi-layer is at least partially alloyed, does not peel off even with a slight rub, and does not cause poor drilling by carbon dioxide laser irradiation.

As the base material of the multi-layer metal foil 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 thermosetting resin of the multiple metal foil clad board of the present invention, a generally known thermosetting resin is 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 same applies to the resin used for the inner layer plate.

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, and 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 appropriate combinations. If necessary, the compound having a reactive group is appropriately blended with a curing agent and a catalyst.

An insulating inorganic filler can be added to the thermosetting resin composition used in the present invention. Especially for carbon dioxide gas laser drilling, 10
8080% by weight, preferably 20-70% by weight. The kind of the insulating inorganic filler is not particularly limited. Specific examples include talc, calcined talc, aluminum hydroxide, kaolin, alumina, wollastonite, synthetic mica, glass powder, and the like, and one or more of them may be used in combination. The shape of the inorganic filler is not particularly limited, and is spherical, acicular, fibrous,
An amorphous type or the like can be used.

The thermosetting resin composition itself is cured by heating, but when the curing speed is low and the workability and economic efficiency are poor, a known thermosetting catalyst for the thermosetting resin used is 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.

When a through-hole and / or a blind via hole is made in a multi-metal foil clad board with a carbon dioxide gas laser, a carbon dioxide gas laser beam is directly radiated onto the shiny surface of the multi-metal foil to process the multi-metal foil and make a hole. Do. The wavelength of the carbon dioxide laser is 9.3 to 10.6 μm. The energy is preferably 5 to 60 mJ, and a predetermined pulse is applied to form holes. The pore size is preferably between 80 and 180 μm. In the case of drilling through holes and / or via holes, any of a method of irradiating holes with the same energy from the beginning to the end, and a method of piercing by increasing or decreasing the energy on the way may be used.

In drilling with the carbon dioxide laser of the present invention, burrs of multiple metal foils and copper foils are generated around the holes.
The method of etching and removing the multi-metal and copper burrs generated in the hole is not particularly limited.
02-22887, 02-22896, 02-25089, 02-25090, 02
-59337, 02-60189, 02-166789, 03-25995, 03-
60183, 03-94491, 04-199592, and 04-263488 disclose a method for dissolving and removing a metal surface with a chemical (S
UEP method). The etching rate is generally
Perform at 0.02 to 1.0 μm / sec. Also, when etching and removing the burrs of the inner layer multiple metal foil or copper foil, at the same time also partially remove the surface of the multiple metal foil or copper foil in a planar manner, preferably a thickness of 2 to 7 μm, more preferably. By setting the thickness to 3 to 5 μm, a fine pattern can be formed on the subsequent metal-plated multiple metal foil or copper foil, and a high-density printed wiring board can be obtained.

A metal plate can be simply disposed on the back surface of the multi-layered metal foil-clad plate in order to prevent the laser machine table from being damaged by a laser when a hole is penetrated. A resin layer to which at least a part of the surface is adhered is adhered to the back metal foil of the multiple metal foil-clad board, and the resin layer and the metal plate are peeled off after drilling through holes. Drilling can also be performed continuously. in this case,
A method of perforating with a carbon dioxide laser while continuously flowing the multiple metal foil-clad sheet while floating in the air, a method of perforating by pressing against a lower table, and the like can be used. In most cases, a resin layer of about 1 μm is left on the surface of the metal foil on the surface of the processed hole where the resin of the surface layer, the inner layer multiple metal foil or the copper foil is adhered. This resin layer can be removed in advance by a generally known treatment such as a desmear treatment before etching. However, when the liquid does not reach the inside of the small-diameter hole, a residue of the resin layer remaining on the surface of the inner layer copper foil or the like may be removed, resulting in poor connection with copper plating.
Therefore, more preferably, first, the inside of the hole is treated in the gas phase to completely remove the residual layer of the resin, and then the inside of the hole and the multiple metal foil burrs and the copper foil burrs on the front and back sides 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 is generally plated with copper. Normal copper plating can be performed, but copper plating can partially fill the inside of the hole, preferably 80% by volume or more. In drilling, of course, excimer laser,
A combined use of a YAG laser or the like is also possible. Further, a mechanical drill can be used in combination.

[0025]

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

Example 1 700 parts of 2,2-bis (4-cyanatophenyl) ether, 200 parts of 1,4-dicyanatobenzene, bis (4-maleimidophenyl)
100 parts of ether was melted at 150 ° C. and reacted for 4 hours while 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 1)
(001, Yuka Shell Epoxy Co., Ltd.) (1000 parts) was added and uniformly mixed. Further, 0.4 part of zinc octylate is added as a catalyst, dissolved and mixed, and 1000 parts of an inorganic filler (trade name: calcined talc, Nippon Talc Co., Ltd., average particle diameter 4 μm), aluminum hydroxide (average particle diameter) 700 And 7 parts of a black pigment were added and uniformly stirred and mixed to obtain Varnish A. This varnish A
Is impregnated into a glass woven cloth having a thickness of 100 μm, dried at 150 ° C., and gelled for 107 seconds (at 170 ° C.), glass cloth content 50 weight
% Of prepreg B was prepared.

As a multiple metal foil having a thickness of 12 μm, a copper layer of 5 μm
/ Nickel layer 2μm / Copper layer 3μm / Nickel layer 2μm
A metal foil having an average unevenness of 3.2 μm on the matte surface, on which the surface was subjected to an alloy treatment of chromium oxide and zinc, was prepared. This multi-layered metal foil is placed on the upper and lower sides of the four prepregs so that the nickel layer on the shiny side is on the outside, and the thickness 1.
Place a 5mm stainless plate, 200 ℃, 20kgf / cm ² , 30mmH
The laminate was laminated under a vacuum of not more than g for 2 hours to obtain a double-sided metal foil-clad laminate C. On the other hand, a resin obtained by dissolving polyvinyl alcohol in water was applied to one side of an aluminum foil having a thickness of 50 μm,
After drying at 20 ° C. for 20 minutes, a backup sheet D having a coating film having a thickness of 20 μm was prepared.

The surface of the double-sided metal foil-clad board C was rubbed 10 times with a cloth, and the abrasion was 1 μm or less. A backup sheet D is placed below the metal foil-clad plate, and 900 holes of 100 μm in diameter within a 50 mm square are radiated from the upper side of the metal foil-clad plate into 5 shots at an output of 10 mJ by pulse oscillation of a direct carbon dioxide gas laser. Then, through holes of 70 blocks (63,000 in total) were formed. The lower backup sheet was removed, and a SUEP solution was sprayed at a high speed to dissolve and remove the metal foil burrs on the front and back, and at the same time, the metal foil on the surface layer was dissolved to a residual thickness of 4 μm.
After depositing copper plating 15μm on the whole, circuit (line / space = 50 / 50μm), solder ball pad, etc. are formed by the existing method, and at least the semiconductor chip part, bonding pad part, solder ball pad part Except for coating with a plating resist, and applying nickel and gold plating, a printed wiring board was prepared. The evaluation results of this printed wiring board are shown.
Shown in 1.

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
A varnish E was prepared by dissolving 35 parts of 2-ethyl-4-methylimidazole in 1 part of a mixed solvent of methyl ethyl ketone and dimethylformamide, and uniformly stirring and mixing. This varnish E is impregnated with a 100 μm thick glass woven fabric, dried, and gelled.
150 seconds, 48% by weight of glass cloth prepreg F, thickness 5
Impregnated into 0 μm glass woven fabric, dried and gelled for 170 seconds,
A prepreg G having a glass cloth content of 31% by weight was prepared.

Using one piece of this prepreg F, place a general 12 μm electrolytic copper foil on the upper and lower sides, 190 ° C., 20 kgf / cm ² , 30 mmH
Laminate molding was performed for 2 hours under a vacuum of not more than g to obtain a double-sided copper-clad laminate H. After forming a circuit on the front and back of the plate and performing black copper oxide treatment, one prepreg G was disposed on each of the front and back of the plate, and multiple metal foils were disposed on both outer sides thereof. This multiple metal foil has a copper layer of 5μm / nickel-cobalt alloy layer of 5μm / copper layer of 2μm
The same general matte surface treatment as in Example 1 was performed on the copper 5 μm side to make the copper foil surface 2.3 μm uneven.
It is a mat-face treated metal foil having a copper / zinc alloy layer formed on its surface. A stainless steel plate having a thickness of 1.5 μm was placed on the outside, and laminated and formed at 180 ° C., 20 kgf / cm ² and a degree of vacuum of 30 mmHg or less to form a four-layer plate I. The backup sheet D was placed below the plate and bonded together with a heating roll at 100 ° C. and 5 kgf / cm. From the upper side of this metal foil clad board, 2 shots with a carbon dioxide laser output of 40 mJ, 15 mJ
And a through hole having a hole diameter of 115 μm was formed.
In addition, one shot was irradiated at an output of 35 mJ and one shot was irradiated at 15 mJ to form a blind via hole having a hole diameter of 90 μm. The entire board was subjected to SUEP treatment to dissolve and remove metal foil burrs, and at the same time, to dissolve and remove the metal foil to a thickness of 3 μm, followed by copper plating according to a standard method to similarly produce a printed wiring board. Table 1 shows the evaluation results.

Comparative Example 1 A copper-clad board was prepared in the same manner as in Example 1 except that a general electrolytic copper foil was used instead of the multiple metal foils, and a carbon dioxide gas laser was directly irradiated on the copper-clad board. Example 1 A hole was drilled under the same conditions, but no hole was drilled.

Comparative Example 2 Example 1 except that a general copper foil was used instead of the multiple metal foils.
In the same manner as described above, a copper-clad laminate was prepared. This surface was subjected to black copper oxide treatment, and thereafter, the surface was rubbed with a cloth 10 times. Then, a carbon dioxide laser was irradiated thereon from the surface under the same conditions as in Example 1, but almost no holes were formed.

Comparative Example 3 2,000 parts of an epoxy resin (trade name: Epicoat 5045, manufactured by Yuka Shell Epoxy Co., Ltd.), 70 parts of dicyandiimide, and 2 parts of 2-ethyl-4-methylimidazole were dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide. Further, 800 parts of the insulating inorganic filler of Example 1 was added, and the mixture was stirred, mixed and uniformly dispersed to obtain a varnish. This was impregnated into a glass woven fabric having a thickness of 100 μm, dried, and gelled for 140 seconds, prepreg J having a glass content of 48% by weight, and impregnated into a glass woven fabric having a thickness of 50 μm, and a gelling time of 180 seconds was used. Glass cloth content 33% by weight
Prepreg K was obtained. Using two prepregs J, place a general 12μm electrolytic copper foil on both sides, 180 ℃, 20kg
Laminate molding was performed for 2 hours under a vacuum of f / cm ² and 30 mmHg or less to obtain a double-sided copper-clad laminate L. Using this copper-clad laminate L, a 150 μm through-hole was formed by mechanical drilling. A carbon dioxide laser with a power of 30 mJ was directly irradiated on the copper foil surface to make via holes, but no holes could be formed. 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 H of Example 2, the upper and lower copper foils were removed by etching so as to have a hole diameter of 100 μm at the portion of the inner layer that would be a through hole, and a circuit was formed. The surface of the copper foil is treated with black copper oxide, one prepreg G is placed on each outer side, and a general 12 μm electrolytic copper foil is arranged on the outer side, and laminated and formed under the same conditions as in Example 2 to form a four-layer copper. It was a veneer. Using this multilayer board, a hole diameter of 10
A hole of 0 μm was made by etching away the copper foil. The surface was irradiated with 4 shots with a carbon dioxide laser at an output of 15 mJ to form through holes. After that, desmearing was performed once without performing SUEP processing in the same manner as in Comparative Example 3, and copper plating was performed for 15 μm.
m, a circuit was formed on the front and back, and a printed wiring board was prepared in the same manner. Table 1 shows the evaluation results.

Table 1 Item Example Comparative example 1 2 2 3 4 Through hole formation (%) 100 100 6 100 100 Gap between front and back land copper foil and hole (μm) 0 0-0 22 Inner layer copper foil Displacement from hole (μm) ー 0 ー ー 36 Pattern break and short (pieces) 0/200 0/200 ー 52/200 55/200 Glass transition temperature (℃) 210 160 ー 139 160 Through hole heat (% ) 100 cycles 1.1 1.3 over 1.6 3.9 300 cycles 1.5 1.7 over 1.8 6.5 drilling time (min) 16 13 over 630 over migration resistance (HAST) (Omega) normal 4x10 ¹¹ over over 1x10 ¹¹ over 200hrs. 8x10 ⁸ <10 ⁸ 500hrs.4x10 ⁸ー 700hrs.2x10 ⁸ 1000hrs.1x10 ⁸

<Measurement method> 1) Gap at the position of front and back holes and the number of holes to be formed A carbon dioxide laser having a hole diameter of 100 μm (carbon dioxide laser) or 150 μm (mechanical drill) as one block of 900 holes and 70 blocks (63,000 holes in total). And the time required to make 63,000 holes in one copper clad board, the gap between the copper foil for land on the front and back, and the hole, and the maximum value of the deviation from the inner layer copper foil. Was. In addition, all the holes were examined for percent formation using a magnifying glass. 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 250μm in each through hole hole, connect 900 holes alternately front and back, one cycle is 260 ° C, solder, immersion 30 seconds → room temperature, 5 minutes, up to 300 cycles The maximum value of the rate of change of the resistance value was shown. 5) Migration resistance (HAST) Copper-plated through-holes with a hole diameter of 100 μm (CO2 laser drilling) or 150 μm (mechanical drilling) are connected alternately on the front and back alternately, and two sets of these are connected between the hole walls. A total of 100 sets were prepared so as to be parallel at 150 μm, taken out at 130 ° C., 85% RH, 1.8 VDC for a predetermined time, and the insulation resistance between the through-hole walls arranged in parallel was measured.

[0037]

According to the present invention, a metal foil cladding using a multilayer metal foil comprising a copper layer and a nickel layer or a nickel alloy layer,
By irradiating the carbon dioxide laser beam directly even when rubbing the metal foil surface during work, through holes and / or blind via holes with a hole diameter of 80 to 180 μm can be formed on the metal foil cladding without defects The processing speed is much faster than mechanical drilling, and the productivity can be greatly improved. Further, thereafter, at the same time as dissolving and removing metal foil burrs and copper foil burrs generated in the holes, partially dissolving and removing the surface of the metal foil in the thickness direction in a plane, and reducing the remaining thickness of the metal foil to 2 to 7 μm. By setting the thickness to preferably 3 to 5 μm, a fine pattern can be formed even in subsequent plating-up by copper plating, and a high-density printed wiring board can be produced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) H05K 3/00 H05K 3/00 NF term (reference) 4E351 AA02 BB01 BB23 BB24 BB30 BB35 BB49 DD04 DD19 DD21 DD54 FF18 GG01 4F100 AA01A AA19 AB16C AB17B AB31C AB33B AK01A AK53 BA03 BA05 BA10A BA10B BA10C BA13 CA23A DC11 DG15 DH01 EJ333 GB43 JB13A JG04A

Claims (7)

[Claims] 1. A carbon dioxide gas laser comprising a multi-layer metal foil in which copper and nickel or nickel alloy layers are alternately arranged as an outer layer of a metal foil clad board having a thermosetting resin composition as an insulating layer. Multi-layer metal foil cladding suitable for drilling with carbon dioxide laser, characterized in that drilling is possible by direct irradiation. 2. The multi-layer metal clad according to claim 1, wherein the surface of the multi-layer metal foil on the carbon dioxide laser irradiation side is a nickel layer or a nickel alloy layer. 3. The multi-metal foil clad board according to claim 1, wherein the surface of the multi-layer metal foil on the carbon dioxide laser irradiation side is a copper layer having a thickness of 3 μm or less. 4. The resin composition according to claim 1, wherein the thermosetting resin composition is a resin composition containing a polyfunctional cyanate ester monomer and the cyanate ester prepolymer as essential components. Multiple metal foil cladding. 5. The multi-ply metal-clad board according to claim 1, wherein the thermosetting resin composition contains 10 to 80% by weight of an insulating inorganic filler. 6. A carbon dioxide laser having an energy selected from 5 to 60 mJ, which is directly irradiated onto the multiple metal foil of the multiple metal foil-clad board according to any one of claims 1 to 5, and has a hole diameter of 80 mm.
A printed wiring board formed by forming through holes and / or blind via holes of up to 180 μm. 7. The method according to claim 1, wherein after forming a hole with a carbon dioxide gas laser, the multiple metal foil burrs generated in the hole are dissolved and removed with a chemical solution, and at the same time, the outer multiple metal foil is partially dissolved and removed in a plane. 5. The printed wiring board according to 5.