JP2947415B2 - Manufacturing method of thin copper foil-clad circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a copper-clad laminate, a copper-clad film, and a copper foil for manufacturing a printed wiring board on which electronic components are mounted and an electrical insulator. A method of manufacturing a copper-clad circuit board or a reinforced copper foil, such as a copper-clad sheet, having a thickness of several μm to 20 μm, and a variation in thickness with respect to a desired thickness of ± 1.0 μm or less. is there.

[Conventional technology and its problems]

The method of manufacturing a copper foil-clad circuit board is a method in which a copper foil and an insulator are laminated and usually manufactured by lamination molding, etc.
Electrolytic thickness 105μm, 70μm, 35μm, 18μm, 1
2 μm and the like are mass-produced, and copper foils such as 5 μm and 9 μm formed on a carrier such as an aluminum foil are also produced.
In addition, there is a copper foil formed by a rolling method. However, the thinner the copper foil becomes, the more expensive it becomes due to the relationship with the manufacturing method, and a foil having a thickness of 35 μm or less has not been practically used.

When such a copper foil is used for lamination molding, its thickness is
When it is thinner than 18 μm, it is apt to be wrinkled, and it is extremely difficult to lay a copper foil on an insulator. Copper foil formed on a carrier such as an aluminum foil improves this point, but is expensive, and requires a step of removing the aluminum foil as a carrier before forming a printed wiring using the copper foil. There was a problem.

Also, a method is known in which a copper foil-clad circuit board is pre-etched with an etchant such as copper chloride or iron chloride in a printed wiring board processing step to polish the copper foil, and then used in a printed wiring board manufacturing step. However, it was not possible to manufacture a thin copper-clad circuit board by increasing the removal amount of copper foil by pre-etching or etching a large area such as 1 m square.

[Means for solving the problem]

As a result of intensive studies on a method of manufacturing a thin copper foil-clad circuit board that can be used as a large-sized circuit board with high productivity, the copper foil of the copper-clad circuit board has a very low speed as compared with the conventional etching method. The present inventors have found that a thin copper-clad circuit board with high thickness accuracy can be obtained by a method of etching the entire surface to remove 25 to 90% of the original copper foil thickness, and arrived at the present invention.

That is, the present invention provides a copper foil-clad circuit board manufactured from a copper foil and an electrical insulator by using 2 to 4 w / v% of hydrogen peroxide,
7w / v% as main agent, alcohol as auxiliary agent 0.1-5w / v
% Using a copper etching solution consisting of an aqueous solution
At a temperature of 25 to 50 ° C and a copper concentration of 30 to 60 g /, 0.01 to 0.3 μm /
The entire surface of the copper foil is etched at a speed of seconds to remove 25 to 90% of the original copper foil thickness, and after the thickness variation of the remaining copper foil is within ± 1.0 μm with respect to the desired thickness, prevention is performed. A method for manufacturing a thin copper foil-clad circuit board, wherein a copper foil surface is protected by a rust agent or a peelable resin.

 Hereinafter, the configuration of the present invention will be described.

The copper foil-clad circuit board manufactured from the copper foil and the electric insulator of the present invention is not particularly limited, and any of various commercially available products used for electronic and electric materials can be used. When applying the manufacturing method of the invention, the nominal thickness is usually
Single-sided or double-sided copper-clad film, sheet, fiber-reinforced insulating resin laminate, metal core laminate using copper foil of 18 μm or more,
Examples include a multilayer shield plate having a printed wiring network formed in an inner layer. The electric insulator layer is made of a film or sheet such as a polyimide resin or a polyester resin, a thermosetting resin or a heat-resistant thermoplastic resin and glass (E glass, D glass, S glass,
Quartz glass (quartz) and others, ceramics (alumina, boron nitride, and others), wholly aromatic polyamides, polyimides, semicarbons, fluorocarbon resins, and other heat-resistant engineering plastics are used alone or in combination as appropriate. Fabricated using a prepreg in combination with a porous film using a fiber, chop or a sheet-like reinforcing substrate, or by coating an insulating adhesive or adhesive film on an iron, aluminum plate, etc. And so on. In addition, in the case of a normal copper-clad laminate, the surface of the copper foil partially reflects the unevenness of the reinforcing substrate due to the pressure of the laminating molding.
The undulation is about μm, but the undulation obtained by mechanically precisely polishing the undulation can also be used.

The copper etching of the present invention reduces the etching rate
The etching rate is in the range of 0.01 to 0.3 μm / sec, preferably in the range of 0.03 to 0.20 μm / sec. 0.3 etching rate
If the speed is faster than μm / sec, the etching proceeds due to a slight difference in the etching processing time, so that not only the intersection with the desired thickness is increased, but also the variation depending on the thickness tends to increase, and the predetermined copper foil thickness It is not preferable because it becomes difficult to make the variation width to ± 1.0 μm or less. On the other hand, when the etching rate is lower than 0.01 μm / sec, the etching takes a long time and is not practical.

In the above, as a method of lowering the etching rate, the concentration, the temperature, or the contact amount of the etching solution on the copper foil surface (in the case of the spray method, the spray pressure or the number of spray nozzles) is reduced. It is preferable to lower the concentration, lower the chemical concentration of the etching solution, or to combine them.

Specifically, the concentration of hydrogen peroxide is preferably 2 to 4 w / v%, the concentration of sulfuric acid is 3 to 7 w / v%, the temperature is preferably 25 to 50 ° C, and the copper concentration is preferably 30 to 60 g /. The method of adding an additive such as a stabilizer for hydrogen peroxide and a dissolution promoter for copper to the hydrogen peroxide / sulfuric acid type etching agent is preferable. Such additives include monohydric alcohols such as methanol, ethanol, propanol and butanol; dihydric alcohols such as ethylene glycol, propylene glycol, butanediol and pentanediol; trihydric or higher alcohols such as glycerin and pentaerythritol; Examples thereof include glycol ethers such as polyethylene glycol; nitrogen-containing organic cyclic compounds such as aminobenzoic acid, aminotetrazole, and phenylurea, and are appropriately selected usually from a range of 0.1 to 5%.

In addition, in the case of a cupric chloride etching solution containing CuCl ₂ as a main component, for example, CuCl ₂ .2H ₂ O 1.421b and HCl (20 ° B.
e ′) 0.6 gal dissolved to make 1 gal aqueous solution (CuCl ₂ ·
2H ₂ O 170 g /, using an aqueous solution was HCl 19w / v% aqueous solution) about a concentration below the method at a temperature 30 to 40 ° C. are exemplified.

In the case of a so-called “alkali etching solution” of an aqueous solution containing NH ₄ OH, NH ₄ Cl, Cu, NaClO ₂ , NH ₄ NO ₃ , for example, NH ₄ OH 3m
ol /, NaClO ₂ 10mol /, NH ₄ Cl 1mol /, NH ₄ HCO ₃ 1mo
l /, NH ₄ NO ₃ and 1mol / degree of concentration or less, the Cu concentration in the aqueous solution 10 lb / gal (74.89g /) or less, a temperature 30-45 ° C.
Or the normal solution concentration and the etching temperature
A method of setting the temperature to about 20 to 30 ° C. is exemplified.

In the case of a persulfate etching solution containing (NH ₄ ) ₂ S ₂ O ₈ as a main component, for example, an aqueous solution having a concentration of about ₂ lb / gal (240 g /) or less of (NH ₄ ) ₂ S ₂ O ₈ is used. A method performed at a temperature of 3535 ° C. is exemplified.

40 ゜ B for an etchant containing ferric chloride as the main component
For example, a method in which 20% to 1% by volume of 35% HCl is added to the ferric chloride solution of e 'or a solution obtained by diluting the solution with water at 20 to 35 ° C. is used.

In the case of a chromic acid / sulfuric acid etching solution, for example, CrO ₃ 2
An example is a method using an aqueous solution having a concentration of about 40 g /, Na ₂ SO ₄ 40.5 g /, H ₂ SO ₄ (96%) of about 180 g / or less.

However, for example, the alkali etching solution has a disadvantage that the stability of the solution is poor, the persulfate etching solution has a disadvantage that the etched copper tends to precipitate from the aqueous solution, and the ferric oxide etching solution has a change in the dissolved copper concentration. In the present invention, a hydrogen peroxide / sulfuric acid based etching solution is used for controlling the solution. Select from points such as points and pollution.

As an etching method in the production method of the present invention, spray etching is usually appropriate, and is performed horizontally or vertically. In order to form a copper foil having a predetermined thickness by etching, a method of setting an etching time by measuring an etching rate under a predetermined etching condition using an etchant is used. For example, to use a double-sided copper-clad board with copper foil of the same thickness on both sides, and to make the both sides the same thickness at the same time horizontally, control the spray pressure etc. so that the etching rates on the upper and lower sides are the same The etching rate is made uniform by performing the etching for a predetermined time. In addition, the method of standing vertically cannot be performed in the above-described methods such as the so-called alkali etching because of the problem of the working environment. However, in the case of a hydrogen peroxide / sulfuric acid system, both sides are simultaneously sprayed at the same spray pressure. This is one of the preferable methods because the etching can be performed at the same rate and it is not necessary to correct the difference in the etching rate between the upper and lower surfaces as in the case where the substrate is placed horizontally. Further, in the conventional etching machine, a method is generally adopted in which the jet direction of the nozzle is made as perpendicular as possible to the surface of the laminate moving at a constant speed. As long as it is sprayed uniformly, it can be used at an angle of about 30 to 50 degrees.

Etching rate by the method described in detail above preferably 0.03 ~ 0.20μm / second etch the entire copper foil at a rate of ± 1.0μm of the thickness variation of the remaining copper foil of the predetermined thickness
This makes it possible to form high-density wiring in the subsequent printed wiring manufacturing process. For example, a thin copper-clad board having a thickness of about 9 μm to 3 μm can be easily manufactured with high thickness accuracy by etching a copper-clad laminate using a copper foil having a nominal thickness of 18 μm (1/2 OZ). The adhesive strength of the copper-clad laminate can be utilized as it is. A copper-clad plate having a thickness of about 12 μm to 20 μm has a nominal thickness of 35 μm (1
It is similarly manufactured by etching a copper-clad laminate using a copper foil of OZ).

After the copper foil surface of the laminate treated with the above-mentioned etching agent is cleaned, it is appropriately dried, and then a rust preventive agent is applied or the resin is coated with a peelable resin to protect the copper foil surface.

Here, the cleaning may be a known method of removing impurities such as neutralization, acid washing, water washing, and hot water washing, and is appropriately selected in consideration of a stabilizer and other components of the used copper etching solution, but is usually selected. It is preferable to perform neutralization → acid washing → (rust prevention or protection film coating).

After being appropriately dried, the copper foil surface is protected by the rust inhibitor of the present invention or a peelable resin. Examples of the rust preventive include known copper rust preventives, such as azole compounds such as benzotriazole, and those obtained by appropriately using a surfactant or the like in combination. Also, as the peelable resin, polyethylene, polypropylene, ethylene-propylene resin,
Ethylene-vinyl acetate resin, vinylidene chloride, polyacrylate copolymer, 1,2-polybutadiene resin, polyester resin, other thermoplastic resin films and photoresist films; paraffin wax, polyethylene wax, rosin, low molecular weight polystyrene Resin-soluble resins such as general-purpose resins; photoresist resin liquids, etc., which may be directly press-bonded to the cleaned copper foil surface, or may be further press-bonded to the rust-proofed surface to form a copper foil. Cover the surface.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The thickness of the etched copper foil was measured by an eddy current method.

Example 1 A glass cloth-based epoxy resin laminate having a 1020 × 1020 mm plate thickness of 1.6 mm and a nominal 18 μm copper foil (Nikko Gourde Co., TC foil) stretched on both sides was subjected to hydrogen peroxide / sulfuric acid using a horizontal spray etching machine. Etching solution (Mitsubishi Gas Chemical Co., Ltd.,
_{FES-6000, H 2 O 2} = 7.78w / v%, H 2 SO 4 = 11.7w / v%) of 3
Etching was performed using a double dilution under the following conditions.

. Etching conditions.・ Temperature 30 ° C ・ Spray pressure 1.5kg / cm ^{2 on the} upper surface 1.3kg / cm ² on the lower surface ・ Cu = 40g / ・ Etching rate 0.18μm / sec Then neutralization → acid washing → water washing, then water-soluble rust prevention An eddy current type film thickness meter (Denso Kogyo Co., Ltd.) ), Dermes eddy current film thickness meter, type DS-1) was used to measure the thickness of the copper foil to continuously apply the thin copper-clad plate shown in Table 1 to 10
Were manufactured.

Comparative Example 1 The procedure of Example 1 was repeated except that a stock solution of FES-6000 was used as an etching solution, and the etching conditions were as follows. The results are shown in Table 1.

. Etching conditions.・ Temperature 50 ℃ ・ Spray pressure Upper surface 1.5kg / cm ^2, Lower surface 1.0kg / cm ²・ Cu = 40g / ・ Etching rate 0.63μm / sec Comparative Example 2 Ten double-sided boards similar to those of the example were manufactured under the conditions of 40 kg / cm ² , 170 ° C., and 2 hours of lamination using a 9 μm nominal thickness single-sided electrolytic copper foil. It was extremely difficult to handle the 9 μm copper foil without wrinkles, and wrinkles occurred in 30% of the laminated molded articles. Table 2 shows the measurement results of the obtained double-sided boards.

Comparative Example 3 A double-sided board was manufactured in the same manner as in Comparative Example 2 using copper foil having a nominal thickness of 9 μm on a 40 μm-thick aluminum foil and a foil having a plated surface with unevenness, and then the aluminum foil was removed by etching. The measurement result of the obtained double-sided board is
It is shown in the table.

[Functions and Effects of the Invention] As described above, according to the production method of the present invention, as is clear from the detailed description of the invention and the Examples and Comparative Examples, a copper foil equivalent to or more than the case using a conventional aluminum clad copper foil It is understood that a thin copper-clad laminate having a thickness accuracy can be easily manufactured, and that the peel strength of copper thin is excellent.

As a result, thin copper-clad laminates that could only be produced by a method using a copper foil of 5 μm or 9 μm or the like formed on a carrier such as an expensive aluminum foil can be manufactured accurately and inexpensively easily. It is understood that this is possible, and its industrial significance is extremely large.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-65868 (JP, A) JP-A-62-200796 (JP, A)

Claims (1)

(57) [Claims] 1. A copper foil-clad circuit board produced from a copper foil and an electrical insulator is made mainly of hydrogen peroxide 2-4 w / v%, sulfuric acid 3-7 w / v%, and alcohol as an auxiliary agent in an amount of 0.1-4.0 w / v%. Use a copper etching solution consisting of an aqueous solution containing 5 w / v%
° C, at a copper concentration of 30 to 60 g /, etching the entire surface of the copper foil at a rate of 0.01 to 0.3 μm / sec, 25 to 90 of the original copper foil thickness
%, And the copper foil surface is protected by a rust inhibitor or a peelable resin after the thickness variation of the remaining copper foil is within ± 1.0 μm with respect to a desired thickness. Substrate manufacturing method.