JPH11340605A - Forming method of penetrating hole for through-hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which directly and accurately opens a through-hole of small diameter on a copper clad plate at one time and at high speed, by using only carbon dioxide gas laser of high output energy. SOLUTION: In a boring method, which opens a penetrating hole for a through-hole on a copper clad plate having at least two copper layers by directly casting carbon dioxide gas laser by using energy selected from 20-60 mJ/pulse which is sufficient for eliminating a copper foil with carbon dioxide gas laser, a coating film or a sheet of organic material which contains 3-97 vol.% of metal compound powder, whose melting point is at least 900 deg.C and bonding energy is at least 300 kJ/mol, and one kind or at least two kinds of carbon powder is arranged on the surface of a copper foil of a copper clad plate which is irradiated with carbon dioxide gas laser, and a penetrating hole is opened by direct irradiation of carbon dioxide gas laser. After that, it is preferable that the burrs of a hole part and a part of the surface of the copper foil be removed through etching, and a penetrating hole for a printed wiring board is formed. As a result, a penetrating hole superior in through-hole reliability, where deviation of hole positions on the surface and the back is excluded can be formed at a high speed, and a penetrating hole suitable for circuit formation of high concentration can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a through hole for a copper clad board having at least two copper layers instead of a mechanical drill. More specifically, a through-hole for through-holes, in which an auxiliary material is arranged on the surface of the copper foil and the carbon dioxide laser is directly irradiated from above by applying the energy of a high-output carbon dioxide laser without etching away the surface copper foil in advance. A method for forming the same. The printed wiring board using the copper clad board obtained by the perforation is mainly used for a small semiconductor plastic package.

[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 small, so the drill bends, breaks, and the processing speed when drilling. It has disadvantages such as slowness, and has problems in productivity, reliability, and the like. Also, if holes of the same size are made in advance by using a negative film on the upper and lower copper foils in a predetermined method, and if a through hole that passes through the upper and lower There were disadvantages such as displacement and difficulty in forming lands. Furthermore, the circuit width and space of high-density printed wiring boards have become increasingly narrower, and some have been created with lines / spaces of 100 μm / 100 μm or less. Was bad.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and uses the energy of a high-output carbon dioxide gas laser to directly apply a carbon dioxide gas laser to a copper-clad plate having an auxiliary drilling material disposed on the surface. And a method for forming a small-diameter hole at high speed and with high reliability of the hole wall. In addition, the generated burrs are removed by etching with a chemical solution, and a part of the surface copper foil is also removed by etching. In the subsequent copper plating, excellent through-hole reliability is achieved, and high-density circuits are also formed in the surface circuit formation. It is intended to be able to form.

[0004]

[Means for Solving the Problems] The CO2 laser is oscillated by pulse oscillation of the CO2 laser using an energy selected from an energy of 20 to 60 mJ / pulse which is sufficient to remove the copper foil with the CO2 laser. Irradiation, in the drilling of through holes by processing the copper foil of the copper clad board having at least two copper layers, on the copper foil surface irradiated with carbon dioxide laser, melting point 900 ° C. or more, In addition, an organic coating film or sheet containing 3 to 97% by volume of a metal compound powder having a binding energy of 300 kJ / mol or more and one or more components of carbon powder is arranged to form a through hole for a through hole. By drilling in the copper-clad plate, a large number of small-diameter through-holes for through-holes could be formed with high accuracy. After that, both surfaces of the metal foil are etched two-dimensionally,
By etching away part of the thickness of the original metal foil, the copper burrs that overhang the hole at the same time are also etched away, forming a through-hole plating hole with copper foil on both sides around the hole remaining. By doing so, the copper foil positions of the upper and lower holes do not shift, lands can be formed, through holes can be formed without bending in the vertical direction, and since the copper foil becomes thin, the metal plating is A high-density printed wiring board could be produced without the occurrence of defects such as short-circuits and pattern breaks in the circuit formation of the fine wires of the front and back copper foils obtained by plating up. In addition, a processing speed was remarkably higher than that of the case of drilling, and a product having good productivity and excellent economic efficiency was obtained. After drilling through holes for through holes, the surface can be polished by a machine other than the method of etching with a chemical solution. However, it is preferable to perform etching with a chemical solution also from the viewpoint of removing burrs and forming fine patterns. Drilling can be performed not only on a double-sided board but also on a multilayer board.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention uses the energy of a high-output carbon dioxide gas laser selected from 20 to 60 mJ / pulse to apply a copper foil surface of a double-sided board having at least two or more copper layers. This is a method of arranging auxiliary materials directly and irradiating a carbon dioxide laser directly to form through holes for through holes.After that, the burrs of the copper foil generated in the holes are removed by etching with a chemical solution, and at the same time, the surface of the copper foil is removed. A part thereof is removed by etching to obtain a copper-clad board used for a high-density printed wiring board having through holes for through holes.

[0006] The copper-clad board used in the present invention includes an inorganic or organic base-reinforced thermosetting resin copper-clad laminate, a double-sided board having copper foil on both sides of a film, and a multilayer board thereof.
Among them, using a glass cloth as a base material, using a thermosetting resin composition as an insulating layer, mixing a dye or a pigment to black, and mixing an inorganic insulating filler by 10 to 60% by weight,
A double-sided copper-clad laminate or a multilayer board having a homogeneous structure is suitably used.

As the substrate, generally known organic and inorganic woven fabrics and nonwoven fabrics can be used. As the inorganic substrate, a glass woven fabric or a nonwoven fabric is preferably used. Specifically, examples of glass fibers include E, S, D, and N glass. Examples of the organic fibers include wholly aromatic polyamide fibers and liquid crystal polyester fibers. These may be mixed. Furthermore, a polyimide film or the like can also be used as a base material, and a resin layer is adhered to at least one side of the base material.

As the resin of the thermosetting resin composition 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 the thermosetting resin component of the present invention is a compound having two or more cyanato groups in the molecule. Specifically, 1,3-
Or 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-, 1,4-, 1,6-, 1,8-, 2,6- or 2,7-dicyanato Naphthalene, 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 43-1846
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 trimerizing a cyanato group of these polyfunctional cyanate compounds is also 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 also suitably used for the purpose of the present invention. Generally, it is used after being dissolved in a soluble organic solvent.

As the epoxy resin, a generally known epoxy resin can be used. Specifically, liquid or solid bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin; butadiene, pentadiene, vinylcyclohexene, dicyclopentyl ether, etc. And polyglycidyl compounds obtained by reacting a polyol, a hydroxyl-containing silicone resin with an epohalohydrin, and the like. These may be used alone or in combination of two or more.

As the polyimide resin, generally known ones can be used. Specific examples include a reaction product of a polyfunctional maleimide and a polyamine, and a polyimide having a terminal triple bond described in JP-B-57-005406.

These thermosetting resins may be used alone, but it is preferable to use them in an appropriate combination in consideration of the balance of properties.

Various additives can be added to the thermosetting resin composition of the present invention, if desired, as long as the inherent properties of the composition are not impaired. These additives include polymerizable double bond-containing monomers such as unsaturated polyesters and prepolymers thereof; polybutadiene, epoxidized butadiene, maleated butadiene, butadiene-
Low molecular weight liquid to high molecular weight elastic rubbers such as acrylonitrile copolymer, polychloroprene, butadiene-styrene copolymer, polyisoprene, butyl rubber, fluororubber, natural rubber; polyethylene, polypropylene, polybutene, poly-4-methyl Penten, polystyrene, A
S resin, ABS resin, MBS resin, styrene-isoprene rubber, polyethylene-propylene copolymer, 4-fluoroethylene-6-fluoroethylene copolymers; polycarbonate, polyphenylene ether, polysulfone, polyester, polyphenylene sulfide, etc. High molecular weight prepolymers or oligomers; polyurethanes and the like are exemplified, and are appropriately used. In addition, various additions of known organic fillers, thickeners, lubricants, defoamers, dispersants, leveling agents, photosensitizers, flame retardants, brighteners, polymerization inhibitors, thixotropic agents, etc. Agents are used in appropriate combination as desired. If necessary, the compound having a reactive group is a curing agent,
A catalyst is appropriately blended.

The thermosetting resin composition of the present invention is itself cured by heating, but has a low curing rate, and is inferior in workability, economy and the like. Therefore, a known thermosetting catalyst can be used for the thermosetting resin used. Use amount is thermosetting resin 10
0.005 to 10 parts by weight, preferably 0.01 to 5 parts by weight per 0 parts by weight
Parts by weight.

As the inorganic insulating filler, generally known ones can be used. Specifically, silicas such as natural silica, calcined silica, and amorphous silica; white carbon, titanium white, aerosil, clay, talc,
Examples include wollastonite, natural mica, synthetic mica, kaolin, magnesia, alumina, and pearlite. The amount of addition is not particularly limited, but is 10 to 60% by weight, preferably 15 to 50% by weight.

Preferably, a black dye or pigment is added to the resin so that the light is not dispersed by the irradiation of the carbon dioxide laser. The particle diameter is preferably 1 μm or less for uniform dispersion. As the types of the dye and the pigment, generally known insulating ones can be used. The addition amount is preferably 0.1 to 10% by weight. Further, glass fibers or the like in which the surface of the fibers is dyed black may be used.

A generally known copper foil can be used as the outermost layer. Preferably, an electrolytic copper foil having a thickness of 3 to 18 μm or the like is used.

The glass cloth substrate-reinforced copper-clad laminate is first impregnated with a thermosetting resin composition into the glass cloth substrate and dried to form a B stage. The glass content is not particularly limited.
Generally, a prepreg is prepared so as to have a concentration of 30 to 65% by weight. Next, a predetermined number of the prepregs are used, copper foils are arranged on the upper and lower sides, and laminated under heat and pressure to form a double-sided copper-clad laminate. In the cross section of the copper clad laminate, the resin and inorganic filler other than glass are uniformly dispersed, and the holes are uniformly formed when laser drilling is performed. In addition, because of the black color, the laser beam is not dispersed, and there is no unevenness on the hole wall, and the film is homogeneous.

The copper clad board or the multilayer board has a melting point of 900 ° C. or more and a binding energy of 300 kJ / mol, which is used as a part of an auxiliary material, on the surface of the copper foil at the hole forming position of the carbon dioxide laser irradiation surface. As the above metal compounds, generally known compounds can be used. Specifically, as the oxide, titania such as titanium oxide; magnesia such as magnesium oxide; iron oxide such as iron oxide; nickel oxide such as nickel oxide; manganese oxide such as manganese dioxide; Zinc oxides such as zinc oxide; silicon dioxide, aluminum oxide, and rare earth oxides; cobalt oxides such as cobalt oxide; tin oxides such as tin oxide; and tungsten oxides such as tungsten oxide. Also,
E, A, C, L, D, S. Glass powder such as M and N is a mixture of the above metal oxides, and these are also preferably used.

Examples of the non-oxide include generally known non-oxides such as silicon carbide, tungsten carbide, silicon nitride, titanium nitride, aluminum nitride, barium sulfate, calcium carbonate, and rare earth oxysulfide. In addition, carbons can also be used. These are used alone or in combination of two or more.

A material that does not adversely affect the adhesion of the semiconductor chip, the hole wall, etc., due to the substance scattered by the carbon dioxide laser adhering to the hole wall or the like is used. Since Na, K, Cl ions and the like particularly adversely affect the reliability of the semiconductor chip, those containing these components are not preferred. The blending amount is 3-97
% By volume, preferably 5 to 95% by volume. Particle size is 1μ
m or less is preferable.

There is no particular limitation on the organic material of the auxiliary material, but an organic material that does not peel off when it is mixed and applied to the surface of the copper foil and dried or formed into a sheet is selected. Preferably, a resin is used. In particular, water-soluble resins such as polyvinyl alcohol, polyester, and starch, which are generally known from the viewpoint of the environment, are preferably used.

The method for preparing a composition comprising a metal compound powder, a carbon powder and an organic substance is not particularly limited. Using the composition, add the metal compound powder and carbon powder to this, stir and mix uniformly, use this, apply it as a paint on the copper foil surface, dry it to make a film, apply it to the film and sheet it And the like. Although the thickness is not particularly limited, it is preferable that the entire thickness arranged on the surface of the copper foil is preferably 30 to 200 μm. As the film to be applied, a known film can be used. For example, a film such as polyethylene terephthalate is preferably used. The thickness is not particularly limited, but is preferably
25-200 μm. The film-attached resin layer is preferably
It is used by being laminated on a copper-clad laminate at a temperature higher than the melting point of the resin.

A coating film made of a resin composition containing one or more of a metal compound powder and a carbon powder on the surface of the copper foil at the hole forming position of the surface of the copper clad plate to be irradiated with the carbon dioxide laser;
Alternatively, place the sheet and directly squeeze it to the desired diameter,
Drilling is performed by irradiating a carbon dioxide laser of one energy selected from high output power of 20 to 60 mJ / pulse. The energy output can be changed during the drilling, and one energy is appropriately selected for the drilling.

When a carbon dioxide laser is irradiated with an energy selected from an output of 20 to 60 mJ / pulse to form a through hole, burrs are generated around the hole. Since mechanical polishing is performed in a normal printed wiring board manufacturing process, it is also possible to perform mechanical polishing several times to remove burrs. However, if polishing is repeated, there is a disadvantage that the plate is elongated, which is not preferable. For this reason, after carbon dioxide laser irradiation, both surfaces of the copper foil or copper alloy foil are planarly etched, and by removing a part of the thickness of the original metal foil surface by etching, burrs are also simultaneously removed by etching. In addition, the obtained copper foil is suitable for forming a fine pattern, and forms a through hole for through-hole plating in which the copper foil on both sides around the hole suitable for a high-density printed wiring board remains.

The method of etching and removing copper burrs generated in the holes according to the present invention is not particularly limited. For example, Japanese Patent Application Laid-Open Nos. 02-22887, 02-22896, 02-25089 and 02-2.
5090, 02-59337, 02-60189, 02-166789, 03-25
995, 03-60183, 03-94491, 04-199592, 04-263
No. 488 discloses a method of dissolving and removing a metal surface with a chemical (referred to as a SUEP method). The etching rate is generally 0.02 to 1.0 μm / sec. The desired thickness of the copper foil on the front and back sides is 3 to 7 μm, and the pressure of a spray or the like is also adjusted so as to remove burrs at the same time.

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
0 mJ / pulse, preferably 22 to 55 mJ / pulse.

[0029]

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 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 1001, Yuka Shell Epoxy Co., Ltd.)
) And 600 parts of a cresol novolac type epoxy resin (trade name: ESCN-220F, manufactured by Sumitomo Chemical Co., Ltd.) were uniformly mixed and dissolved. Further, as a catalyst, zinc octylate 0.4
Was added, and the mixture was dissolved and mixed. To this, 500 parts of an inorganic insulating filler (trade name: BST # 200, having an average particle diameter of 0.4 μm, manufactured by Nippon Talc Co., Ltd.), and 8 parts of a black pigment were added. Varnish A was obtained by uniform stirring and mixing. This varnish is impregnated with a glass woven fabric having a thickness of 100 μm and dried at 150 ° C., and a gel time (at 170 ° C.)
For 120 seconds, a prepreg (prepreg B) having a glass cloth content of 57% by weight was prepared. Electrolytic copper foil having a thickness of 12 μm was placed above and below the four prepregs B, and the temperature was 200 ° C., 20 kgf / cm ² , 30
Laminate molding for 2 hours under vacuum of mmHg or less, insulation layer thickness 400μ
m of the double-sided copper-clad laminate C was obtained. On the other hand, M with an average particle size of 0.9 μm
gO 43% by weight, SiO ₂ 57% by weight of metal oxide powder,
The polyvinyl alcohol powder was added to a varnish dissolved in water, and uniformly stirred and mixed (varnish D). This was applied on the double-sided copper-clad laminate C to a thickness of 50 μm and dried at 110 ° C. for 30 minutes to form a film having a metal oxide content of 90% by volume (FIG. 1 (1)). From above, at an interval of 300 μm, a pore diameter of 100
900 pulses of 900 μm diameter were directly applied with a carbon dioxide laser at an output of 40 mJ / pulse, and 7 pulses (shots) were applied to form 70 blocks of through-holes (Fig. 1 (2)). Surface coating
After washing and removing with hot water of 60 ° C, the copper foil burr around the hole is dissolved and removed by the SUEP method, and the copper foil on the surface is also thickened.
It was dissolved to 7 μm (FIG. 1 (3)). This plate was plated with copper by a usual method at 15 μm (total thickness: 22 μm) (FIG. 1).
(4)). All of the land copper foil around this hole remained. A circuit (line / space = 50 / 50μm 200 pieces), a land for solder balls, etc. are formed on the front and back sides in the usual way, except for at least the semiconductor chip mounting part, the bonding pad part, and the solder ball pad part. The substrate was covered with a plating resist, plated with nickel and gold, and a printed wiring board was prepared. Table 1 shows the evaluation results of the printed wiring board.

Example 2 A double-sided copper-clad laminate was prepared in the same manner as in Example 1 except that no black dye was added to the resin composition, and a metal oxide paint was applied to the surface in the same manner and dried to form a film. After forming the holes, holes were drilled by irradiating 7 pulses (shots) at an output of 40 mL / pulse of a carbon dioxide laser. Thereafter, a printed wiring board was prepared in the same manner. Table 1 shows the evaluation results.

Example 3 Epoxy resin (trade name: Epicoat 5045) 700 parts, epoxy resin (trade name: ESCN220F) 300 parts, dicyandiamide 35
And 1 part of 2-ethyl-4-methylimidazole were dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide, and 800 parts of the calcined talc of Example 1 (trade name: BST # 200) was added. Then, varnish E was obtained. This is impregnated with a 100 μm thick glass woven fabric, dried, and gelled.
A prepreg (prepreg E) having a glass cloth content of 55% by weight for 150 seconds was prepared. Using two pieces of this prepreg E, put 18μm electrolytic copper foil on both sides, 190 ℃, 20kgf / cm ² , 30mmHg
Laminate molding was performed for 2 hours under the following vacuum to prepare a double-sided copper-clad laminate F. The thickness of the insulating layer was 200 μm. Circuits were formed on the front and back sides of this, and a black copper oxide treatment was applied to the copper foil to form an inner layer plate (referred to as an inner layer plate F). The varnish E was impregnated into a liquid crystal polyester fiber nonwoven fabric having a thickness of 80 μm and dried to obtain a prepreg having a gelation time of 105 seconds. This prepreg is placed above and below the inner layer plate F, and 12 μm
Of electrolytic copper foil, and laminated and molded in the same manner to form a four-layer multilayer board G
I got On the other hand, black copper oxide powder having an average particle size of 0.9 μm was dissolved in a mixed solution of polyvinyl alcohol and trimethylolpropane, and this was applied to one surface of a polyethylene terephthalate film having a thickness of 50 μm so as to have a thickness of 35 μm. It dried at 25 degreeC for 25 minutes, and produced the film-form auxiliary material H of copper oxide powder 12 volume%. After placing the auxiliary material H on the above-mentioned multilayer board G and laminating it at a temperature of 95 ° C., 9 pulses of 30 mJ / pulse of carbon dioxide laser were output from above.
In (shot), a through hole for a through hole having a hole diameter of 80 μm was formed. Subsequent processing was performed in the same manner as in Example 1 to produce a printed wiring board. Table 1 shows the evaluation results.

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

Comparative Example 2 Using the double-sided copper-clad laminate of Example 1, the surface of the area to be drilled was coated with black magic and irradiated with a carbon dioxide gas laser in the same manner, but no hole was formed.

Comparative Example 3 In Example 3, Epicoat 50 was used as an epoxy resin.
Using a multi-layer board made in the same way, using 1,000 parts of 45 alone, arranging auxiliary material H on the copper foil surface in the same way,
Similarly, 19 shots were irradiated with a carbon dioxide laser at 17 mJ / pulse, and a through hole for a through hole was opened. In this hole wall, glass fiber was found in the hole, and the hole shape was not a perfect circle but an elliptical shape. A printed wiring board was prepared only by mechanical polishing once without performing the SUEP process. Table 1 shows the evaluation results.

Comparative Example 4 Using the double-sided copper-clad laminate of Example 1, holes were drilled at intervals of 300 μm with a mechanical drill having a diameter of 100 μm at a rotation speed of 100,000 rpm and a feed speed of 1 m / min. Two drills broke on the way. Mechanical polishing was performed once, and copper plating was similarly performed at 15 μm without performing the SUEP treatment, circuits were formed on the front and back surfaces, and the same processing was performed to produce a printed wiring board. Table 1 shows the evaluation results.
Shown in

Comparative Example 5 900 holes having a hole diameter of 100 μm were formed in the copper foil surface of the double-sided copper-clad laminate of Example 1 at intervals of 300 μm, and the copper foil was etched. Similarly, a hole with a hole diameter of 100 μm
6 pieces of copper-clad laminates with 63,000 holes drilled in total, 70 blocks of 1 pattern (Fig. 2 (1)), and 7 pulses at the output of 40 mJ / pulse with carbon dioxide laser from the surface ( Shot) to form a through hole for a through hole (FIG. 2 (2)). Thereafter, in the same manner as in Comparative Example 3, copper plating was performed 15 μm with only one mechanical polishing (FIG. 2).
(3)) 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 Practical example Comparative example 1 2 3 3 4 5 0 0 0 0 0 25 Misalignment of front and back land position (μm) Hole shape Round Circle Round Elliptical Round Upper circular Lower elliptical Hole Inside Linear Almost Straight line almost straight Inner wall concave straight line almost straight convex large pattern cut and 0/200 0/200 0/200 55/200 57/200 57/100 short (piece) Glass transition temperature 235 235 160 139 234 235 (℃) Heat 2.5 2.8 5.7 25.0 2.6 5.0 Heat cycle test (%) Pressure Normal condition 6x10 ¹³ー ー 6x10 ¹³ー ー Cooker treatment 200hrs.4x10 ¹² 3x10 ⁹ Insulation resistance after 500hrs.5x10 ¹¹ <10 ⁸ value (Ω) 700hrs.3x10 ¹¹ー1000hrs.9x10 ¹⁰ Anti-migration Normal 5x10 ¹³ー ー 6x10 ¹³ー 200hrs.4x10 ¹² 8x10 ⁹ (Ω) 500hrs.5x10 ¹¹ 1x10 ⁹ 700hrs.3x10 ¹¹ <10 ⁸ 1000hrs.1x10 ¹¹ー Drilling time 21 21 26 ー 630 ー (min)

<Measurement method> 1) Misalignment of the front and back hole positions and drilling time Holes with a hole diameter of 100 μm, 900 holes within a 250 mm square work size,
70 blocks (total of 63,000 holes) were prepared. When drilling with a carbon dioxide laser and a mechanical drill, the time required for drilling 63,000 holes / sheet and the maximum value of the gap between the front and back holes are shown. 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 200μm in each through-hole, connect 900 holes alternately to the front and back, and one cycle is 260 ° C, solder and soak
200 cycles were performed from 30 seconds to room temperature for 5 minutes, and the maximum value of the rate of change in resistance was shown. 5) Insulation resistance value after pressure cooker treatment In Examples and Comparative Examples, line / space = 50/50 μm
Select the one with no pattern breaks and shorts, apply black copper oxide treatment, place one identical prepreg on top of this, place 12 μm electrolytic copper foil on it, and laminate under the same conditions It was formed into a multilayer board. After forming a circuit on this, it was put in 121 ° C. and 2 atm for a predetermined time, taken out, and left at 25 ° C. and 60% RH for 2 hours.
After applying for 0 seconds, the insulation resistance value between the terminals was measured. 6) Migration resistance A through hole with a gap of 300 μm and a hole diameter of 100 μm is independently connected one by one alternately on the front and back sides, and 100 sets of these are made, and 50 VDC is applied in an atmosphere of 85 ° C / 85% RH. Get in,
The insulation resistance value between the through holes after the treatment for a predetermined time was measured. 7) Hole shape The cross section of the hole and the shape from above were observed.

[0039]

According to the present invention, the pulsed oscillation of the carbon dioxide gas laser uses the energy selected from the high output of 20 to 60 mJ / pulse which is sufficient to remove the copper foil with the carbon dioxide gas laser.
A method of forming a through hole for a through hole in a copper-clad plate having at least two or more copper layers, at least on a copper foil surface irradiated with a carbon dioxide laser, a melting point of 900 ° C. or more,
And a metal compound powder having a binding energy of 300 kJ / mol or more,
An organic coating or sheet containing 3 to 97% by volume of one or more types of carbon powder is arranged, and a carbon dioxide laser is directly irradiated with necessary pulses to form holes. At the same time as dissolving and removing with a chemical solution, part of the copper foil surface layer is also dissolved and removed, and a through hole used for a through hole of a printed wiring board with high density and good hole shape can be formed, and there is no displacement of the hole position on the front and back In addition, the hole wall had almost no unevenness, and a through-hole having excellent connection reliability was obtained. Also, the processing speed is much faster than drilling,
Productivity can be greatly improved.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a process diagram of a through hole for a through hole by a carbon dioxide laser of Example 1, (1): formation of a resin film containing a metal compound powder, (2): hole formation and film removal,
(3): Deburring by SUEP, (4): Step of copper plating.

FIG. 2 is a view showing a similar through-hole drilling process using a carbon dioxide gas laser of Comparative Example 5. However, SUEP is not used.

[Explanation of symbols]

a Resin layer containing metal compound powder b Copper foil c Thermosetting resin layer of glass cloth base d Drilled through hole through hole by carbon dioxide gas laser e Burr generated

Claims (2)

[Claims] 1. Copper having at least two or more copper layers by pulse oscillation of a carbon dioxide gas laser using energy selected from 20 to 60 mJ / pulse sufficient to remove a copper foil with a carbon dioxide gas laser. In a method of forming a through hole for a through hole in a veneer, a metal compound powder having a melting point of 900 ° C. or more and a binding energy of 300 kJ / mol or more is formed on at least a copper foil surface irradiated with a carbon dioxide laser. A method for forming a through hole for a through hole, comprising arranging an organic coating film or sheet containing 3 to 97% by volume of a species or two or more species and irradiating a carbon dioxide gas laser. 2. A hole for a through hole is formed by etching away a part of the copper foil on both surfaces of the perforated copper clad plate and simultaneously removing burrs of the hole. 2. The method for forming a through hole for a through hole according to claim 1.