JPH11320174A - Auxiliary material for carbon dioxide gas laser boring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an auxiliary material for making a through hole with a smaller diameter, and a via hole at high accuracy and high speed by directly radiating a carbon dioxide gas laser of high power to a copper-clad plate. SOLUTION: In case of this auxiliary material, a coating or sheet-like auxiliary material composed of a resin composition material including 3-79 volume % of at least one kind or, two or more kinds of metallic powder is disposed on a copper-clad plate, and the energy chosen from that of 20-60 mj/pulse of the carbon dioxide gas laser power is radiated from the above for boring the copper foil on the surface. By using the auxiliary material for copper foil surface, the carbon dioxide gas is directly radiated for boring the copper foil. Thereby, the through hole and the via hole can be formed at high accuracy and high speed, and a hole for a printed wiring board with improved economy can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary material for directly irradiating a copper surface of a copper clad board having at least one copper layer with a carbon dioxide gas laser to form a hole. More specifically, the present invention relates to an auxiliary material for forming through-holes or via holes in copper-clad boards such as copper-clad boards and multilayer boards. The copper-clad board and the multilayer board obtained by the present invention are mainly used for small-sized printed wiring boards for high-density semiconductor plastic packages having small-diameter holes.

[0002]

2. Description of the Related Art Hitherto, in high-density printed wiring boards used for semiconductor plastic packages and the like, through holes for through holes have been drilled. In recent years, the diameter of drills has become smaller and smaller, and the hole diameter has been reduced to 0.15 mmφ or less.When drilling such small holes, the drill diameter is so small that the drill bends, breaks, and reduces the processing speed when drilling. There are drawbacks such as slowness, causing problems in productivity, reliability, and the like. In addition, when irradiating a carbon dioxide gas laser, direct irradiation of the copper foil surface with the carbon dioxide gas laser reflects the laser beam and does not form a hole. Conventionally, the surface copper foil is first etched to a predetermined size. Then, the exposed portion of the resin was processed by irradiating a carbon dioxide laser thereto, thereby forming a via hole. In this case, when a small-diameter hole having a diameter of 100 μm or less is etched in the copper foil, defects such as poor hole diameter accuracy are found when the copper foil is thick. Also, when drilling through holes for through holes, use a negative film on the upper and lower copper foils in advance and drill holes of the same size by a predetermined method, and use a carbon dioxide laser to form through holes that penetrate the upper and lower sides. In this case, the positions of the upper and lower holes are displaced, and there are disadvantages such as difficulty in forming a land.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and provides a carbon dioxide gas laser drilling auxiliary material for forming a small diameter through hole for a through hole and a via hole. .

[0004]

According to the present invention, there is provided a resin composition comprising one or more metal powders containing 3 to 97% by volume of a metal powder, or a sheet obtained by applying the same to a thermoplastic film or the like. By arranging on the copper foil surface with a total thickness of 30 to 200 μm, it is easy to make holes in the copper foil of the copper clad board. That is, according to the present invention, a carbon dioxide laser having an energy selected from an output of 20 to 60 mJ / pulse of a carbon dioxide laser is directly irradiated to the copper foil surface by pulse oscillation to form a through hole for a through hole.
■ Process copper foil with one energy of 60mJ / pulse, stop when it reaches the resin layer, then output 20
~ 35mJ / pulse or reduce output to 20
The present invention provides a processing auxiliary material which is used by being arranged on a surface copper foil when forming a via hole by processing a resin layer at less than mJ / pulse, preferably 5 to 19 mJ / pulse. It is also possible to stack several auxiliary materials for processing and copper-clad boards alternately, or to place auxiliary materials for processing on top and several copper-clad boards underneath, and process with a carbon dioxide laser from above. is there. After processing, the surface of the copper foil can be deburred by mechanical polishing, but in order to completely remove the burr, both surfaces of the copper foil are etched flat and a part of the original metal foil is removed. By removing the thickness by etching, the copper foil burrs protruding in the holes are also removed by etching to form through holes for through holes in which the copper foil remains around the holes. By forming holes and deburring as described above, lands can be formed without displacement of copper foil positions of upper and lower holes, through holes can be formed without bending up and down, and copper foil can be formed. In order to create a high-density printed wiring board, there is no short-circuit or broken pattern, etc. Can be. In addition, the processing speed is much faster than when a mechanical drill is used, the productivity is good, and the economy is excellent.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a carbon dioxide laser having an energy selected from 20 to 60 mJ / pulse sufficient to remove copper foil, and at least one layer, preferably two or more layers. In a copper-clad board with a copper layer, through-holes for through-holes, via holes, etc. And an auxiliary material for drilling comprising a paint or a sheet in which a metal powder and an organic substance are mixed. By irradiating the surface of the copper foil directly with a carbon dioxide gas laser from above the auxiliary material and processing and removing the copper foil, a through hole for a through hole and a via hole are formed or the formation thereof is facilitated.

[0006] The copper-clad board used in the present invention is a copper-clad board having one or more layers, preferably two or more layers of copper. Thermosetting resin copper-clad laminate of the material, the copper-clad laminate is used for the inner layer, copper foil with resin, or inorganic, organic base material reinforced thermosetting resin layer is placed on the outside, and further on the outside And a copper-clad board of a generally known configuration such as a multilayer board obtained by laminating and forming a copper foil if necessary. In addition, generally known materials such as a copper-clad board or a multilayer board in which a copper foil is bonded to a heat-resistant film such as a polyimide film or a polyparabanic acid film can also be used.

As the substrate, generally known woven or nonwoven fabrics of inorganic or organic fibers can be used. Specifically, examples of the inorganic fiber include E, A, C, L, M, S, D, N, quartz glass, and the like, and these are used alone or in combination. Examples of the organic fibers include wholly aromatic polyamides and liquid crystal polyesters.

The resin of the thermosetting resin composition used in the present invention includes generally known thermosetting resins. Specific examples include an epoxy resin, a polyfunctional cyanate ester resin, a polyfunctional maleimide-cyanate ester resin, a polyfunctional maleimide resin, and an unsaturated group-containing polyphenylene ether resin. Are used in combination. A thermosetting resin composition having a glass transition temperature of 150 ° C. or higher is preferable in order to make the shape of a through-hole processed by irradiation of a high-output carbon dioxide laser appropriate. In consideration of moisture resistance, migration resistance, electrical characteristics after moisture absorption, and the like, a polyfunctional cyanate resin composition is preferred.

The polyfunctional cyanate compound which is a preferred thermosetting resin component of the present invention is a compound having two or more cyanato groups in a molecule. Specific examples include 1,3- or 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-, 1,4-, 1,6-, 1,8
-, 2,6- or 2,7-dicyanatonaphthalene, 1,3,6-
Tricyanatonaphthalene, 4,4-dicyanatobiphenyl, bis (4-dicyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, 2,2-bis (3,
5-dibromo-4-cyanatophenyl) propane, bis
(4-cyanatophenyl) ether, bis (4-cyanatophenyl) thioether, bis (4-cyanatophenyl) sulfone, tris (4-cyanatophenyl) 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 43-18
468, 44-4791, 45-11712, 46-41112, 4
Polyfunctional cyanate compounds described in 7-26853 and JP-A-51-63149 can also be used. Further, the molecular weight of the polyfunctional cyanate compound having a triazine ring formed by trimerization of a cyanato group of
0-6,000 prepolymers are also used. This prepolymer is obtained by polymerizing the above-mentioned polyfunctional cyanate ester monomer using, for example, an acid such as a mineral acid or a Lewis acid; a base such as a sodium alcoholate or a tertiary amine; a salt such as sodium carbonate as a catalyst. 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. The thermosetting resin is usually used by dissolving it 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 group-containing silicone resin with an ephalohydrin, 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 thereof include a reaction product of a polyfunctional maleimide and a polyamide, 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, fluoro rubber, natural rubber; polyethylene, polypropylene,
Polybutene, poly-4-methylpentene, polystyrene, AS resin, ABS resin, MBS resin, styrene-isoprene rubber, polyethylene-propylene copolymer,
-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. In addition, other known organic fillers, dyes, pigments, thickeners, lubricants, defoamers, dispersants, leveling agents, photosensitizers, flame retardants, brighteners, polymerization inhibitors, thixotropic agents And various other additives are used in combination as needed. 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.

As the metal powder used in the drilling auxiliary material of the present invention, generally known ones can be used. Specifically, a simple substance of titanium, iron, copper, nickel, manganese, zinc, cobalt, tin, tungsten, or the like, or an alloy thereof can be used. These are used alone or in combination of two or more. It is preferable that the carbon dioxide laser is applied so that the metal does not adhere to the hole walls and the like and does not adversely affect the semiconductor chip and the adhesion to the hole walls during copper plating.
Since Na, K ions and the like have a particularly bad influence on the reliability of the semiconductor, these metals are not suitable. On the surface of the copper foil, 3 to 97% by volume, preferably 5 to 95% by volume or less in the auxiliary material is used, and is usually a powder having an average particle size of 5 μm or less, and is blended with an implicit substance, particularly a resin composition, Dispersed uniformly. The average particle size is particularly preferably 1 μm or less.

The organic material of the auxiliary material is not particularly limited, but those which do not peel off when kneaded and applied to the copper foil surface and dried, or when applied to a thermoplastic film to form a sheet are selected. Is done. Preferably, a resin is used. In particular, in consideration of the environment or cleaning of the copper foil surface after processing, a water-soluble resin such as polyvinyl alcohol, polyester, or starch is preferably used.

The method of preparing the auxiliary material using the composition comprising the metal compound and the resin is not particularly limited, but is a method in which the mixture is kneaded at a high temperature without a solvent using a kneader or the like and extruded into a sheet, or dissolved in a solvent or water. Using a resin composition, add metal powder to this, stir and mix uniformly, apply this as a paint to the copper foil surface, dry it to form a film, spray directly onto the copper foil surface, spray it onto the film, A generally known method such as a method of coating and drying to form a sheet, a method of impregnating an organic or inorganic substrate, and drying to form a substrate-containing sheet can be used.

As the outermost copper foil of the copper clad board, generally known ones can be used. Preferably, an electrolytic copper foil having a thickness of 3 to 18 μm is used.

In the substrate-reinforced copper clad board, first, the above-mentioned substrate is impregnated with a thermosetting resin composition and dried to form a B stage to prepare a prepreg. Next, a predetermined number of the prepregs are used, copper foil is arranged on at least one side, and laminated and formed under heat and pressure to obtain a copper-clad board.

At least on the copper foil surface of the copper-clad board or the multilayer board on which the carbon dioxide laser is irradiated, at the hole forming position,
A coating or sheet comprising a resin composition containing 3 to 97% by volume of metal powder, preferably 5 to 95% by volume, preferably has a total thickness of 30 to
One having a thickness of 200 μm is arranged. 20-60m from above
By irradiating a high-output one-energy carbon dioxide laser beam selected from J / pulse, the copper foil is processed and drilled.

When holes are formed by irradiating a carbon dioxide laser with an energy selected from an output of 20 to 60 mJ / pulse, burrs occur around the holes. Therefore, after the carbon dioxide laser irradiation, both surfaces of the copper foil are etched two-dimensionally, and the thickness of a part of the original metal foil is removed by etching, thereby simultaneously removing the burrs by etching. This allows
The obtained copper foil is suitable for forming a fine pattern, and a through hole for a through hole or a via hole in which the copper foil around the hole suitable for a high-density printed wiring board remains is formed.

The method for etching and removing the copper burrs generated in the holes and part of the front and back copper foils is not particularly limited. For example, JP-A Nos. 02-22887, 02-22896, 02-25
089, 02-25090, 02-59337, 02-60189, 02-
166789, 03-25995, 03-60183, 03-94491, 0
A method of dissolving and removing the metal surface with a chemical (referred to as a SUEP method) disclosed in JP-A-4-199592 and JP-A-04-263488 is adopted. Etching rate is generally 0.02-1.0μ
Perform at m / s.

The carbon dioxide laser is in the infrared wavelength range.
Wavelengths of 9.3 to 10.6 μm are commonly used. Output is 20-6
The copper foil is processed and drilled at 0 mJ / pulse, preferably at 22-50 mJ / pulse.

[0025]

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

Example 1 900 parts of 2,2-bis (4-cyanatophenyl) propane,
100 parts of bis (4-maleimidophenyl) methane was melted at 150 ° C. and reacted for 4 hours with stirring to obtain a prepolymer. This was dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide. 400 parts of bisphenol A type epoxy resin (trade name: Epicoat 1001, Yuka Shell Epoxy Co., Ltd.) and cresol novolac type epoxy resin (trade name: ESCN-220F, Sumitomo Chemical Co., Ltd.)
600 parts were added and uniformly dissolved and mixed. Further, 0.4 part of zinc octylate is added as a catalyst, and the mixture is dissolved and mixed. To this, 500 parts of inorganic filler (trade name: calcined talc BST- # 200, manufactured by Nippon Talc Co., Ltd.) and 8 parts of black pigment are added, and the mixture is uniformly stirred. The varnish A was obtained by mixing. The varnish A was impregnated with a glass woven fabric having a thickness of 100 μm, dried at 150 ° C., and subjected to a gelation time (at1
A prepreg (prepreg B) having a glass cloth content of 54% by weight was prepared for 120 seconds at 70 ° C.). Place 12μm thick electrolytic copper foil above and below the 4 prepregs B at 200 ℃, 20k
Laminate molding was performed for 2 hours under a vacuum of gf / cm ² and 30 mmHg or less to obtain a double-sided copper-clad laminate C having an insulating layer thickness of 400 μm.

On the other hand, copper powder (average particle diameter: 0.7
μm) was added to a varnish prepared by dissolving polyvinyl alcohol in water, and uniformly mixed by stirring (varnish D). This was coated on the double-sided copper-clad laminate C at a thickness of 35 μm,
After drying for 0 minutes, a film having a metal content of 10% by volume was formed. From above, 90 μm holes with a hole diameter of 100 μm are placed at intervals of 300 μm.
Eight pulses (shots) were applied with a direct carbon dioxide laser at an output of 40 mJ / pulse, and 70 blocks of through-holes were drilled (FIGS. 1 (1) and (2)). 60 ° C for surface coating
Then, after the desmear treatment, the copper foil burrs around the holes were dissolved and removed by the SUEP method, and the copper foil on the surface was also dissolved to 6 μm (FIG. 1 (3)). This plate was plated with copper by 15 μm (total thickness: 21 μm) by an ordinary method (FIG. 1 (4)). All of the land copper foil around this hole remained. A circuit (line / space = 50/50 μm 200 pieces), a land for solder balls, etc. are formed on the front and back sides by a standard method, and a plating resist is used except for at least a semiconductor chip mounting portion, bonding pads, and solder ball pads. It was coated and plated with nickel and gold to produce a printed wiring board. Table 1 shows the evaluation results of the printed wiring board.

Example 2 A metal powder (stainless steel SUS304, average particle diameter: 0.6) was added to an aqueous resin solution comprising polyvinyl alcohol and starch.
μm) and uniformly stirred and mixed.
10μm thick polyethylene terephthalate film
And dried at 110 ° C. for 25 minutes to obtain a film-form auxiliary material E having a metal content of 95% by volume. On the other hand, 700 parts of an epoxy resin (trade name: Epicoat 5045), 300 parts of an epoxy resin (trade name: ESCN220F), 35 parts of dicyandiamide, and 1 part of 2-ethyl-4-methylimidazole are dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide. And calcined talc (trade name; BST- # 200)
Was added and 5 parts of a black pigment were added, and the mixture was uniformly stirred and forcedly dispersed to obtain Varnish F. This is impregnated into a 100-μm-thick glass woven fabric, dried, and gelled for 150 seconds.
A 55% by weight prepreg (prepreg G) was prepared. The prepreg G was used two, placing the electrolytic copper foil of 12μm on both sides, 190 ° C., 20 kgf / cm ^2, 30 mmHg 2 under a vacuum of less than
Laminate molding was performed for two hours to produce a double-sided copper-clad laminate H. The thickness of the insulating layer was 200 μm. One sheet of the auxiliary material E and two sheets of the copper-clad laminate H were placed under the sheet, and 10 pulses were irradiated at an output of 30 mJ / pulse of a carbon dioxide gas laser, and a through hole for a through hole having a hole diameter of 80 μm was formed. This surface was treated by the SUEP method in the same manner as in Example 1 to obtain a printed wiring board. Table 1 shows the evaluation results.

Comparative Example 1 Using the double-sided copper-clad laminate C of Example 1, a hole was similarly formed with a carbon dioxide laser without performing a surface treatment, but no hole was formed.

Comparative Example 2 Using the double-sided copper-clad laminate C of Example 1, the surface of the copper foil where the holes were to be drilled was painted with black magic, and the carbon dioxide laser was similarly irradiated, but no holes were formed.

Comparative Example 3 In Example 2, Epicoat 5045 was used as an epoxy resin.
Using 1,000 parts alone, using the double-sided copper-clad laminates prepared in the same way, placing the auxiliary material E on the copper foil surface,
Similarly, 50 shots were irradiated with a carbon dioxide laser at an output of 17 mJ / pulse, and a through-hole for a through-hole was formed. In this hole wall, glass fiber was partially found in the hole, and the hole shape was not a perfect circle but an elliptical shape. Thereafter, a copper-plated circuit was formed in the same manner as in Example 2 to produce a printed wiring board. In this example, processing by the SUEP method was not performed.
Table 1 shows the evaluation results.

COMPARATIVE EXAMPLE 4 Using the double-sided copper-clad laminate C of Example 1, with a mechanical drill having a diameter of 100 μm, the number of rotations was 100,000 rpm, and the feed rate was 1 m / min.
In the same manner, holes were made at 300 μm intervals. Thereafter, similarly, copper plating was applied to a thickness of 15 μm, circuits were formed on the front and back surfaces, and processed in the same manner to form a printed wiring board. The processing by the SUEP method was not performed. Two drill breaks occurred on the way. Table 1 shows the evaluation results.

Comparative Example 5 An interval of 300 μm was provided on the copper foil surface of the double-sided copper-clad laminate C of Example 1.
, 900 holes having a hole diameter of 100 μm were formed by etching the copper foil (FIG. 2 (1)). Similarly, 900 holes with a hole diameter of 100 μm are opened at the same position on the back surface, and 900 holes in one pattern are 70 blocks, and a total of 63,000 holes are applied from the front surface with a carbon dioxide gas laser and output 8 pulses (shots) at an output of 40 mJ / pulse. ,
A through hole for a through hole was formed (FIG. 2 (2)). Thereafter, in the same manner as in Comparative Example 4, copper plating was performed at 15 μm (FIG. 2).
(3)) A circuit was formed on the front and back, and a printed wiring board was prepared in the same manner. Also in this example, processing by the SUEP method was not performed. Table 1 shows the evaluation results.

<Measurement Method> 1) Misalignment of the front and back holes and drilling time 70 holes (diameter: 63,000) were formed in a work size of 250 mm square at 900 holes / block with 100 μm holes. Drilling was performed with a carbon dioxide gas laser and a mechanical drill, and the time required for drilling 63,000 holes in one copper-clad laminate and the maximum value of the misalignment between the front and back holes were shown. 2) Circuit pattern breakage and short circuit line of the printed wiring board created in Examples and Comparative Examples
After etching the pattern of space = 50/50 μm with a magnifying glass, 200 patterns were visually observed, and the total of the cut 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 A 200-μm diameter land was created in each through-hole, 900 holes were connected alternately on the front and back, and 260 cycles of soldering, immersion for 30 seconds → room temperature, 1/5 cycle were performed 200 times. And the maximum value of the rate of change of the resistance value.

Table 1 Item Example Comparative Example 1 2 3 4 5 Offset of front and back hole position (μm) 0 0 0 0 25 Shape of hole Circular Circular Elliptical Circular Circular Circular hole Wall shape Straight line Large unevenness Straight line Almost straight Short (number) 0/200 0/200 55/200 57/100 57/200 Glass transition temperature (℃) 235 160 139 235 235 Through-hole heat cycle test (%) 2.4 3.9 25.9 2.6 5.0 Drilling time (min) 24 15-630-Note: The shape of the hole was the same in the upper and lower parts in Examples 1 and 2 and Comparative Examples 3 and 4, but in Comparative Example 5, the upper part was circular and the lower part was deformed.

[0036]

According to the present invention, one energy selected from 20 to 60 mJ / pulse sufficient for removing a copper foil with a carbon dioxide laser is used, and a carbon dioxide laser is directly applied to the copper foil surface by pulse oscillation. An auxiliary material for drilling is provided, which is used on the surface of the copper foil when irradiating to form holes in the copper foil of the copper clad board. By using the auxiliary material for drilling of the present invention, the copper surface of the copper-clad board having at least one or more copper layers is directly irradiated with a high-output one-energy carbon dioxide laser to form a copper foil. When drilling, there is no need to remove the copper foil in advance by etching, and in the through hole for through hole, there is no displacement of the hole position on the front and back of the copper clad plate, which is several tens of times as compared with the case of drilling with a mechanical drill. Processing can be performed at twice the processing speed, and productivity is greatly improved.
In addition, both surfaces of the copper foil are planarly etched by post-processing after drilling, and the thickness of a part of the original copper foil is removed by etching. High-density printed wiring boards without defects such as short-circuits and pattern breaks. Excellent semiconductor packaging is provided.

[Brief description of the drawings]

FIG. 1 is a process diagram of a through hole for a through hole by a carbon dioxide gas laser of Example 1.

FIG. 2 is a similar process drawing using a carbon dioxide gas laser of Comparative Example 5.

[Explanation of symbols]

a Resin layer containing metal powder b Copper foil c Thermosetting resin layer of glass cloth base material d Drilled through hole through hole by carbon dioxide gas laser e Burr generated f Drilled through hole through hole where front and back copper foils are misaligned g Copper-plated through-holes without SUEP treatment

 ──────────────────────────────────────────────────の Continued from the front page (72) Inventor Yoshihiro Kato 6-1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi Gas Chemical Co., Ltd. Tokyo factory

Claims (2)

[Claims] 1. A copper foil surface is irradiated with a carbon dioxide gas laser by pulse oscillation using an energy selected from 20 to 60 mJ / pulse sufficient to remove the copper foil with the carbon dioxide gas laser. Use of an organic coating or sheet containing at least one metal powder or two or more metal powders in an amount of 3 to 97% by volume as a drilling auxiliary material used on the copper foil surface when forming a hole by processing An auxiliary material for carbon dioxide laser drilling characterized by the following. 2. The coating or sheet has a total thickness of 30 to 200.
The auxiliary material for drilling according to claim 1, wherein the thickness is μm.