JP2001179876A - Method for manufacturing insulating resin with copper foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject method capable of effectively removing the resin powder generated from an insulating resin with a copper foil. SOLUTION: A method for manufacturing an insulating resin with a copper foil has a process for forming an insulating resin layer on the single surface of the copper foil and cutting the coated copper foil into a necessary size and subsequently treating the cut part of the insulating resin with the copper foil with a liquid for dissolving the insulating resin layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an insulating resin with a copper foil.

[0002]

2. Description of the Related Art With the miniaturization and multi-functionality of electronic devices, printed wiring boards are also required to be thinner and higher in density. As a method of forming the same, as a substitute for the conventional drill, various companies have proposed a method of manufacturing a multilayer printed wiring board using laser processing capable of forming fine holes.

For example, a copper foil with an insulating adhesive is laminated on an inner layer circuit board to form an insulating layer and a copper foil, and only the copper foil at a necessary portion of a via hole is selectively removed by etching. Create an opening in the copper foil, drill a hole to reach the inner layer conductor connecting the outer layer circuit and the inner layer circuit by laser processing the insulating layer exposed in the opening, and perform desmear processing to remove the resin residue, Plating to electrically connect the copper foil and the inner layer conductor, removing unnecessary portions of the copper foil and the plating by etching to form an outer layer circuit, or forming an insulating layer on the inner layer circuit board and forming a via The hole in the insulation layer where the hole is required is drilled by laser processing to reach the inner layer conductor connecting the outer layer circuit and the inner layer circuit, desmearing is performed to remove resin residue, and the inner wall of the hole and the surface of the insulation layer are required. Plating only on Is a method of forming an inner layer conductor and electrically connected to the outer circuit.

[0004]

By the way, in the manufacturing process of such a multilayer printed wiring board, an insulating resin varnish is applied to a copper foil to form an insulating layer.
It is made by drying and making it into a semi-cured state, layered on the inner circuit board, and laminated by heating and pressing,
To apply the insulating resin varnish to the copper foil, unwind the coiled copper foil, apply the insulating resin varnish continuously, pass through a drying oven, and add the semi-cured copper foil. It is wound and manufactured as an insulating resin, and is cut to the required size and used when laminated with an inner circuit board. However, at the time of this cutting, resin powder is generated from the insulating resin with the copper foil, which enters between the metal mirror plate and the insulating resin with the copper foil at the time of lamination and becomes uneven on the surface of the multilayer printed wiring board. This is a cause of defective circuit formation during the production of a circuit pattern.

An object of the present invention is to provide a method for manufacturing an insulating resin with a copper foil, which can effectively remove resin powder generated from the insulating resin with a copper foil.

[0006]

According to the method for producing an insulating resin with a copper foil of the present invention, an insulating resin layer is formed on one surface of a copper foil, cut into a required size, and then cut into portions of the insulating resin with a copper foil. Is treated with a liquid that dissolves the insulating resin layer.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a liquid for dissolving the insulating resin layer of the present invention, an organic solvent used for producing an ordinary insulating resin with a copper foil can be used, but drying after treatment at a vapor pressure of 20 mmHg or more is required. Those that are easy to implement are preferred. Particularly preferred organic solvents include methanol, acetone, methyl ethyl ketone and the like.

[0008] The resin used in the present invention is preferably a thermosetting resin, and more preferably an epoxy resin. Such an epoxy resin,
The thermosetting resin composition comprises an epoxy resin and a curing agent. The thermosetting resin composition may further include a curing accelerator, a catalyst, an elastomer, a flame retardant, and the like, if necessary.

The epoxy resin may be any epoxy resin having an epoxy group in the molecule, such as a bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol S epoxy resin, an alicyclic epoxy resin, Group epoxy resin, phenol novolak epoxy resin, cresol novolak epoxy resin, bisphenol A novolak epoxy resin, diglycidyl etherified biphenol, diglycidyl etherified naphthalene diol, diglycidyl etherified phenol And diglycidyl ethers of alcohols, and alkyl-substituted, halogenated and hydrogenated products thereof. These may be used in combination,
Components other than the epoxy resin may be included as impurities.

The epoxy resin curing agent used in the present invention can be used without any limitation as long as it can cure the epoxy resin. Examples thereof include polyfunctional phenols, amines, imidazole compounds, acid anhydrides, organic anhydrides, and the like. Phosphorus compounds and their halides.

Examples of the polyfunctional phenols include monocyclic bifunctional phenols such as hydroquinone, resorcinol, catechol, and polycyclic bifunctional phenols such as bisphenol A, bisphenol F, naphthalene diols, biphenols, and halides thereof. There are alkyl group substituents and the like. Further, there are novolaks and resols which are polycondensates of these phenols and aldehydes.

Examples of amines include aliphatic or aromatic primary amines, secondary amines, tertiary amines, quaternary ammonium salts and aliphatic cyclic amines, guanidines, urea derivatives and the like. is there.

Examples of these compounds include N, N-
Benzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, tetramethylguanidine, triethanolamine, N, N'-dimethylpiperazine, 1,
4-diazabicyclo [2,2,2] octane, 1,8-
Diazabicyclo [5,4,0] -7-undecene, 1,
5-diazabicyclo [4,4,0] -5-nonene, hexamethylenetetramine, pyridine, picoline, piperidine, pyrrolidine, dimethylcyclohexylamine, dimethylhexylamine, cyclohexylamine, diisobutylamine, di-n-butylamine, diphenylamine, N -Methylaniline, tri-n-propylamine,
Tri-n-octylamine, tri-n-butylamine,
Examples include triphenylamine, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, triethylenetetramine, diaminodiphenylmethane, diaminodiphenylether, dicyandiamide, tolylbiguanide, guanylurea, and dimethylurea.

Examples of the imidazole compound include imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole,
Benzyl-2-methylimidazole, 2-heptadecylimidazole, 4,5-diphenylimidazole, 2-
Methylimidazoline, 2-phenylimidazoline, 2-
Undecylimidazoline, 2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole, 2-ethylimidazoline, 2-phenyl-4-methylimidazoline, benzimidazole, 1- And cyanoethylimidazole.

Examples of the acid anhydride include phthalic anhydride, hexahydrophthalic anhydride, pyromellitic dianhydride and benzophenonetetracarboxylic dianhydride.

As the organic phosphorus compound, any phosphorus compound having an organic group can be used without any particular limitation. Examples thereof include hexamethylphosphoric triamide, tri (dichloropropyl) phosphate, tri (chloropropyl) phosphate, Examples include triphenyl phosphite, trimethyl phosphate, phenylphosphonic acid, triphenylphosphine, tri-n-butylphosphine, and diphenylphosphine.

These curing agents can be used alone or in combination. The amount of the curing agent for the epoxy resin can be used without any particular limitation as long as the curing reaction of the epoxy group can proceed, but is preferably 0.01 to 5.0 mol per mol of the epoxy group.
It is used in the range of 0 equivalent, particularly preferably in the range of 0.8 to 1.2 equivalent.

The thermosetting epoxy resin composition of the present invention may optionally contain a curing accelerator. Representative curing accelerators include, but are not limited to, tertiary amines, imidazoles, quaternary ammonium salts, and the like.

The resin composition for a wiring board of the present invention may further contain a ceramic whisker. Such a ceramic whisker has an elastic modulus of 200G.
It is preferably Pa or more, and if it is less than 200 GPa, sufficient rigidity cannot be obtained when used as a wiring board material or a wiring board. As such, for example,
One or more selected from aluminum borate, wollastonite, potassium titanate, basic magnesium sulfate, silicon nitride, and α-alumina can be used. Among them, aluminum borate whiskers and potassium titanate whiskers have Mohs hardness almost equal to that of E glass used for a general prepreg base material, and can obtain drillability similar to that of a conventional prepreg. Aluminum borate whiskers have an elastic modulus of approximately 40
It is as high as 0 GPa, easily mixed with the resin varnish, and more preferable.

The average diameter of the whiskers is 0.3 μm
To 3 μm, more preferably 0.5 μm
The range of 〜1 μm is more preferable. When the average diameter of the whiskers is 0.3 μm or less, mixing with the resin varnish becomes difficult. When the average diameter exceeds 3 μm, microscopic dispersion in the resin is not sufficient, and the unevenness of the surface becomes large, which is not preferable. . The ratio of the average diameter to the average length is preferably 10 or more, which can further increase the rigidity, and is more preferably 20 or more. This ratio is 10
If it is less than the above, the reinforcing effect as a fiber becomes small. The upper limit of this average length is 100 μm, and more preferably 50 μm. Exceeding this upper limit makes dispersion in the resin varnish difficult, increases the probability that one whisker contacts two conductor circuits, and increases the probability of copper ion migration along the whisker fiber. Become.

Further, in order to increase the rigidity, heat resistance and moisture resistance of the multilayer printed wiring board, an electrically insulating whisker surface-treated with a coupling agent having excellent wettability with resin and bonding property is used. Preferred as such coupling agents are a silicon-based coupling agent, a titanium-based coupling agent, an aluminum-based coupling agent, a zirconium-based coupling agent, a zirconaluminum-based coupling agent, a chromium-based coupling agent, and a boron-based coupling agent. It can be used by selecting from a coupling agent, a phosphorus-based coupling agent, an amino acid-based coupling agent and the like.

The ratio of the thermosetting resin to the ceramic whiskers is such that the volume fraction of the whiskers in the cured resin is 5%.
It is preferable to adjust so as to fall within the range of 50% to 50%.
If the volume fraction of the whiskers in the cured resin is less than 5%, the prepreg with copper foil (copper foil / thermosetting resin layer) is extremely difficult to handle, such as when the resin is finely crushed and scattered when cut. In addition, the rigidity is reduced when the wiring board is used. On the other hand, if the volume fraction of the whisker exceeds 50%, the filling into holes and circuit gaps at the time of heat and pressure molding becomes insufficient, voids and blurring occur after the molding, and the insulating property decreases. Further, the ratio of the resin to the whisker is more preferably that the volume fraction of the whisker in the cured resin is 20 to 40%.

Further, a laminated board comprising the resin and the metal layer of the present invention is a prepreg obtained by dissolving the above resin composition in a solvent such as methyl ethyl ketone or isopropyl alcohol to form a resin varnish into a glass cloth. age,
Heated and dried to a semi-cured state and layered with metal foil such as copper foil or aluminum foil, and laminated by heating and pressing, or a resin coat of metal foil with a blade coater,
A rod coater, a knife coater, a squeeze coater, a reverse roll coater, a transfer roll coater, or the like, is applied to a uniform thickness, heated and dried to a semi-cured state, or such a resin layer with a metal foil, Laminated on the inner layer circuit board, lamination and integration by heating and pressing, the above prepreg plated on a heat-cured resin plate, the resin varnish on the inner layer circuit board, blade coater, rod Coating with a uniform coater, knife coater, squeeze coater, reverse roll coater, transfer roll coater, etc. After the metal foil is etched off from the laminated and integrated one by heating and pressing, the surface is plated. Things, and the like.

As the inner layer circuit board on which the inner layer circuit is formed, an inner layer circuit board used for a normal printed wiring board can be used, and unnecessary copper foil of the copper-clad laminate for a printed wiring board is removed by etching to form a circuit. Drill holes in the formed or, if necessary, double-sided copper-clad laminate for printed wiring boards.
Electroless plating is performed to form a plating metal on the inner wall of the hole, and if necessary, electrolytic plating is performed to achieve the required thickness for the circuit conductor, and unnecessary copper foil and plating metal are removed by etching to form a circuit. Can be used.

After the resin layer with a metal foil is overlaid on the inner circuit board on which the inner circuit is formed, and laminated by laminating by heating and pressing, a hole reaching the inner layer circuit is formed from above the metal foil. Can be opened by irradiating a laser. When the thickness of the metal foil is large, the metal foil is once removed by etching, a metal layer is formed by plating, and then a via hole can be formed by irradiating a laser from above the metal layer. At this time, it is preferable to roughen the resin layer before plating, and a general acidic oxidizing roughening solution or an alkaline oxidizing roughening solution can be used. For example, as the acidic oxidizing roughening solution, there is a chromium / sulfuric acid roughening solution, and as the alkaline oxidizing roughening solution, a potassium permanganate roughening solution or the like can be used. After the resin layer is roughened with the oxidizing roughening solution, it is necessary to chemically neutralize the oxidizing roughening solution on the surface of the insulating resin, but this can also adopt a general method. For example, when a roughening solution of chromium / sulfuric acid is used, it is treated with 10 g / l of sodium bisulfite at room temperature for 5 minutes, and when a roughening solution of potassium permanganate is used, 150 ml / l of sulfuric acid and peroxide are used. For example, it is immersed in an aqueous solution of 15 ml / l of hydrogen water at room temperature for 5 minutes to complete the neutralization.

Regarding the type of laser of a laser processing machine used for drilling by laser irradiation, carbon dioxide laser, U.S.A.
There is no particular limitation on a V-YAG laser or the like. The drilling conditions must be adjusted depending on the thickness of the metal foil, the type of the resin, and the thickness of the resin, and are preferably obtained experimentally. The energy amount is in the range of 0.001 W to 1 W, A power supply for laser oscillation must be applied in a pulsed form to control so that a large amount of energy is not concentrated at once. The adjustment of the drilling condition is performed in such a manner that a hole reaching the inner layer circuit of the inner layer circuit board is formed, and a pulse waveform duty ratio for driving a laser oscillation power supply is 1/1000 to 1/1000 in order to minimize the hole diameter. In the range of 10,
The number of shots is preferably 1 to 20 shots (pulse). If the waveform duty ratio is less than 1/1000, it takes too much time to form a hole, which is not efficient. If it exceeds 1/10, the irradiation energy is too large and the hole diameter becomes 1 mm or more, which is not practical. The number of shots (pulses) may be determined experimentally as a number that allows the adhesive in the holes to evaporate to the point where the adhesive reaches the inner layer circuit. Even if the waveform duty ratio of the pulse is near 1/1000, the hole diameter becomes large, which is not practical. Also, if the surface of the metal layer is too smooth, it reflects the laser beam and may not evaporate, so it is preferable that the surface is appropriately roughened. The degree of the roughening may be such that it can exhibit a hue that can absorb the laser beam, and for example, may be such a degree that the metal color on the surface becomes cloudy with a chemical etching solution composed of cupric chloride and hydrochloric acid or an ammonium persulfate solution.

In the outer layer circuit, the above metal layer can be used as it is. However, when the inside of the via hole is metallized, there is a possibility that the thickness of the conductor is increased and the etching accuracy is reduced. In some cases, it is preferable to etch away the metal layer. It is preferable to perform desmear treatment to remove the adhesive residue in the via holes, which is known when forming the via holes.This desmear treatment is performed by a general acidic oxidizing roughening solution or alkaline oxidizing solution. A roughening solution can be used. For example, as the acidic oxidizing roughening solution, there is a chromium / sulfuric acid roughening solution, and as the alkaline oxidizing roughening solution, a potassium permanganate roughening solution or the like can be used. After the resin layer is roughened with the oxidizing roughening solution, it is necessary to chemically neutralize the oxidizing roughening solution on the surface of the insulating resin, but this can also adopt a general method. For example, when a chromium / sulfuric acid roughening solution is used, 10 g / l of sodium bisulfite is used at room temperature for 5 hours.
Minutes, and when using a potassium permanganate roughened solution, sulfuric acid 150 ml / l and hydrogen peroxide solution 15 m
For example, it is immersed in a 1 / l aqueous solution at room temperature for 5 minutes to complete the neutralization.

The copper plating performed to form a conductor as an outer layer circuit after the above-described process may be the same method as the electroless plating, or after a thin electroless plating, for example, a copper sulfate bath or a copper pyrophosphate bath. The thickness required for the circuit conductor can be obtained by performing such electrolytic plating. What is important at this time is that the inner wall of the formed via hole is subjected to electroless plating to form plated copper for connecting the inner layer circuit conductor and the outer layer circuit. Thereafter, if the thickness of the circuit conductor is about 1 to 15 μm, it can be formed by electroless plating, and if it exceeds 15 μm, electrolytic plating can be used together. Preferably, in order to form a precise wiring, it is preferable to form the wiring by electroless plating because the surface becomes flat. Also, a plating resist is formed before plating,
The circuit can also be formed by plating only the shape of the circuit.

After copper plating in this manner, an etching resist is formed in the shape of the circuit to be formed, and a portion not covered with the etching resist is removed by using an etching solution containing cupric chloride and hydrochloric acid or ammonium persulfate. The etchant can be removed by spraying to form a circuit. Furthermore, the copper plating is thinned, a plating resist is formed thereon, electrolytic plating is performed only on the shape of the circuit to form a thick conductor, the plating resist is peeled off, and the thin copper underneath is formed. The circuit can also be formed by removing the plating by etching.

[0030]

EXAMPLES 1) A varnish of an insulating resin with a copper foil was prepared using the following materials. -Bisphenol A novolak epoxy resin: Epicron N-865 (Dai Nippon Ink Co., Ltd., trade name) ... 100 parts by weight-Phenol novolak resin: N-740 (Dai Nippon Ink Co., Ltd., trade name) ... 60 parts by weight -Terminal carboxylated acrylonitrile butadiene rubber: PNR-1H (manufactured by JSR Corporation, trade name) ... 30 parts by weight-Alkylphenol formaldehyde resin: Hitanol 2400 (manufactured by Hitachi Chemical Co., Ltd., trade name) ... 3.5 parts by weight-1 -Cyano-2-ethyl-4-methylimidazole: 2E4MZ-CN (manufactured by Shikoku Chemicals Co., Ltd., trade name) ... 0.7 parts by weight-Butanone: ... 150 parts by weight-Talc Talc SWA (manufactured by Asada Flour Milling Co., Ltd.) ) 30 parts by weight, and then kneaded and stirred to prepare a resin varnish. 2) This resin varnish was applied to a copper foil GTS (trade name, manufactured by Furukawa Circuit Foil) having a thickness of 35 μm so that the insulating resin layer after drying and curing had a thickness of 80 μm.
It dried at 120 degreeC for 15 minutes, and produced the insulating resin with a copper foil. 3) After cutting the insulating resin with the copper foil into 100 × 100 mm, a treatment was performed by using methanol as an organic solvent and immersing about 1 mm of the end of the insulating resin with the copper foil in the methanol for 2 seconds. Then, after the same processing was performed on the remaining end, it was put into a dryer kept at 80 ° C. for 1 minute and dried. The amount of resin powder generated for this insulating resin with copper foil was measured. Table 1 shows the results. 4) Apply the treated insulating resin with copper foil to the end of 3) to a glass-epoxy resin copper-clad laminate (laminate thickness: 0.6 m).
m, copper foil thickness 35 μm) and MCL-E-67 (trade name, manufactured by Hitachi Chemical Co., Ltd.), after both surfaces were subjected to copper blackening treatment, and the insulating resin layer was turned to the laminate side and applied under vacuum. Hot and pressure lamination (temperature: 170 ° C., pressure: 3 MPa, holding time: 90
) To produce a multilayer laminate. The multilayer laminate was visually observed, and the number of irregularities on the surface was measured. Further, the multilayer laminate was cut into 25 × 25 mm, and solder heat resistance was evaluated. Table 1 shows the results.

Comparative Example A characteristic evaluation was performed in the same manner as in the example, except that the edge treatment after cutting the insulating resin with the copper foil was not performed. Table 1 shows the results.

[0032]

[Table 1] 発 生 Generated resin powder Number of surface irregularities Solder heat resistance (%) (pcs / dm ² (Second) 例 Example 0.08 0.1 180 or more Comparative Example 0.67 5-10 180 or more ━━━━━━━━━━━━━━━━━━━━━━━━━━━━

(Measurement Method) 1) Amount of Resin Powder Generated Five pieces of insulating resin with copper foil cut to 100 × 100 mm were weighed, and the weight was determined as the weight before dropping. This is vertically picked up on a horizontal laboratory bench, and 2 mm from a height of 20 mm.
After dropping 0 times, the weight was measured and the weight after dropping was used to calculate the amount of resin powder generated by the following equation. Resin powder generation (%) = (weight before drop-weight after drop) /
Weight before drop x 100 2) Number of surface irregularities The insulating resin with copper foil is laminated under heat and pressure under vacuum on a copper-clad laminate that has been subjected to copper blackening treatment. The number of irregularities was measured. 3) Solder heat resistance In the same manner as in 2), an insulating resin with a copper foil was laminated on a copper-clad laminate, cut into 25 × 25 mm, and the time until blistering occurred in a solder bath at 288 ° C. was measured. .

[0034]

As described above, according to the present invention,
It is possible to provide a method for producing an insulating resin with a copper foil, which can suppress the amount of resin powder generated when cutting the insulating resin with a copper foil.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroyuki Fukai 1500 Ogawa, Oji, Shimodate-shi, Ibaraki F-term (reference) 4F100 AB17A AB33A AK01B AK27B AK27 AK27J AK29 AK29J AK33 AK53 AL01 AL05 AL07 AL02 AN02 BA02 EH462 EJ012 EJ322 EJ822 GB43 JG04B JL06

Claims (1)

[Claims] An insulating resin layer is formed on one side of a copper foil and cut to a required size.
A method for producing an insulating resin with a copper foil, comprising a step of treating the insulating resin layer with a liquid that dissolves the insulating resin layer.