JPH0225089A - Manufacturing method for single-sided thin copper foil-clad circuit board - Google Patents

Abstract

PURPOSE:To form an excellent single side copper-clad laminar board by a method wherein both the sides of a both sided copper foil-clad circuit board are subjected to etching through a spray type etching machine using a copper etching solution to leave only one copper foil-clad side unremoved and the ratio of the thickness of the unremoved copper foil to that of the original copper foil is specified. CONSTITUTION:A both sided copper-clad circuit board composed of a copper foil and an electrical insulator is subjected to an etching through a spray type etching machine using a copper etching solution to etch its both sides. In this process, the etching is performed as follows: the copper etching solution is a water solution composed of hydrogen peroxide, sulfuric acid, and persulfate as a main agent, and a stabilizing agent of the main agent, a dissolution promoter, and others are added to the solution; the concentration of an etching component and an etching temperature are kept at a low level; a supplied etching component in contact with the surface the copper foil is made small in volume; and an etching speed is made slow. After the etching process has been finished, the copper foil surface of a laminated board is cleaned and dried up, and then it is coated with a separable resin or a rust preventive is applied onto it. By these processes, a single side thin copper-clad laminar board, whose copper foil is 18mum or less, can be easily formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a single-sided copper foil-clad laminate manufactured from copper foil and an electrical insulator for manufacturing printed wiring boards on which electronic components are mounted;
Single-sided copper foil-clad circuit boards such as single-sided copper-clad film and single-sided copper-clad sheet, especially for use as the outermost layer in the production of high-density sheet or film printed wiring boards and high-density multilayer printed wiring boards. The preferred thickness of copper foil is several -~2
0 prisoners, thickness variation with respect to desired thickness is ±2.0AI
This is a method for producing a single-sided thin copper foil-clad circuit board having a heating time of less than Ta, preferably less than ±1.0 μs.

[Conventional technology and its problems]

Copper foil-clad circuit boards are manufactured by laminating copper foil and insulators, usually by lamination molding, etc. The copper foils used are 105 Js, 70 Js, 35 Js, 18 Js, 18 Js, etc. by electrolytic method.
12fi, etc. are produced, and copper foils, such as 5μs and 9μs, formed on carriers such as aluminum foils are also produced.

Further, there is copper foil made by rolling, but due to the manufacturing method, the thinner the copper foil, the more expensive it becomes, and foils with a thickness of 351 mm or less have not been put to practical use.

When such copper foil is used for laminated molding, its thickness is 1
If the copper foil is thinner than 81, it tends to wrinkle easily and the work of overlapping the copper foil with the insulator becomes extremely difficult, so it is hardly put into practical use. Copper foil formed on a carrier such as aluminum foil improves this point, but is expensive and requires a step to remove the carrier, such as aluminum foil, before forming printed wiring using copper foil. There was a problem.

In addition, in the printed wiring board processing process, the copper foil-clad circuit board is pre-etched with an etching solution such as copper chloride or iron chloride, and the copper foil is polished to improve the adhesion of the resist, after which the printed wiring board is manufactured. Although methods used in this process were known, it was not possible to manufacture a thin copper-clad circuit board by increasing the amount of copper foil removed by preliminary etching or by etching a large area such as 1 m square.

Therefore, one side of the electrolytic copper foil with a thickness of less than 181 cm or a thickness of 201 cm may be used.
Rolled copper foil of less than
It has also been practically difficult to mass-produce double-sided boards coated with copper foil such as ~105p.

[Means for solving problems]

As a result of intensive research into a method for manufacturing thin copper foil-clad circuit boards that can be used as large-scale circuit boards with high productivity, the present invention has been developed as a result of intensive studies on a method for manufacturing thin copper foil-clad circuit boards that can be used as large-scale circuit boards. We have discovered an etching method that has extremely small differences in thickness accuracy due to differences in thickness. moreover,
As a result of further investigation, we have arrived at the present invention.

That is, the present invention involves etching both sides of a double-sided copper foil-clad circuit board made of copper foil and an electrical insulator using a copper etching solution using a spray etching machine, and etching one side of the double-sided copper foil-clad laminate. A method for producing a single-sided thin copper foil-clad circuit board, characterized in that the thickness of the remaining copper foil is 10 to 75% of the thickness of the original copper foil, and the copper foil on the opposite side is completely removed. be.

The configuration of the present invention will be explained below.

The double-sided copper foil-clad circuit board manufactured from the copper foil and electrical insulator of the present invention is not particularly limited, and any of various commercially available products used for electronic and electrical materials can be used. When applying the manufacturing method of the invention, the nominal thickness is usually 1
Double-sided copper-clad films, sheets, fiber-reinforced insulating resin laminates, metal core laminates, and printed wiring networks on the inner layer using copper foil of 84 or higher and varying the thickness of the copper foil on each side as necessary. For example, a multilayer shield plate formed by the above method. The electrical insulator layer is
Films and sheets made of polyimide resin, polyester resin, etc., thermosetting resins, heat-resistant thermoplastic resins, and glass (E
Glass, D glass, S glass, quartz glass (quartz)
Other), ceramics (alumina, boron nitride, etc.), fully aromatic polyamide, polyimide, semi-carbon, fluororesin, other heat-resistant engineering plastics, etc. Products manufactured using prepreg made by combining a porous film or sheet-like reinforcing base material, or products made by coating an iron, aluminum plate, etc. with an insulating adhesive or adhesive film. be.

In addition, in the case of ordinary copper-clad laminates, due to the pressure of lamination molding, the surface of the copper foil partly reflects the unevenness of the reinforcing base material, and for example, in the case of a glass woven base material, it is approximately 40. Although it has undulations with a pitch of about 4p, it is also possible to use a material that has been mechanically precisely polished to a fine unevenness of about 31 or less to remove these undulations.

The copper etching solution of the present invention for etching the above-mentioned double-sided copper foil-clad circuit board contains hydrogen peroxide/sulfuric acid, persulfate, copper chloride, iron chloride, etc. as a main ingredient, a stabilizer for the main ingredient, a copper dissolution promoter, This is an aqueous solution containing auxiliary agents to control the condition of the etched copper foil surface.It can be carried out under strict control under normal etching conditions, but it is not used for normal etching. A method of keeping the concentration of etching components low compared to the etching solution, a method of keeping the temperature low, or the amount of contact of the supplied etching solution on the copper foil surface (
In the case of a spray method, it is preferable to slow down the etching speed by reducing the spray pressure or number of sprays, or by appropriately combining these methods. It is preferable to use a method that lowers the value compared to .

When using hydrogen peroxide/sulfuric acid as an etching solution,
Usually, the concentration of hydrogen peroxide (H20□) is 0.7~14w
/v%, the concentration of sulfuric acid (H, SO,) is 1 to 25 iv/v
It is desirable that the molar ratio of H20□/]1□S04 in % is 0.2 to 1 and the temperature is in the range of 20 to 55°C, especially for thin copper foil-clad circuits with different thicknesses on both sides with stable and high thickness accuracy. In order to manufacture the substrate, the concentration of H2O2 is between 2 and 6 w/v.
%, sulfuric acid concentration is 3-1 h/v%, copper concentration is 30-60 g
/A and the temperature is preferably selected from the range of 25 to 35°C.

It is preferable to add additives such as a hydrogen peroxide stabilizer and a copper dissolution promoter to the hydrogen peroxide/sulfuric acid type etching agent. Such additives include monohydric alcohols such as methanol, ethanol, propatool, and butanol; dihydric alcohols such as ethylene glycol, propylene glycol, butanediol, and bentanediol; and trihydric or higher alcohols such as glycerin and pentaerythritol. Examples include glycol ethers such as polyethylene glycol, nitrogen-containing organic cyclic compounds such as niaminobenzoic acid, aminotetrazole, and phenylurea, and the amount is usually appropriately selected from the range of 0.1 to 5%.

In the case of a cupric chloride etching solution based on CLICI2, for example, CuC]□"2L01.421b and IIc
Dissolve 0.6 gal of I(20°Be') to make an aqueous solution 1
Ga I (CIIC12・28□0170g
An example of a method is to use an aqueous solution having a concentration of about 19 w/v % or less) and carry out at a temperature of 30 to 40°C.

N1140H, NH4Cl, Cu, NaCl0z,
In the case of a so-called "alkaline etching solution" which is an aqueous solution containing NHJOs, for example, NH,OH3mol/j#
NaCl0z 10mol/11NH4C11mol
/jl! ,NH4HCOa 1mol/1,NH,
The concentration of NO3 should be about 1 mol/A or less, and the C in the aqueous solution should be
Examples include a method in which the u concentration is maintained at 10 lb/gal (74.89 g/β) or less and a temperature in the range of 30 to 45°C, or a method in which the etching temperature is maintained at about 20 to 30°C with a normal solution concentration.

(Nl+4) 2S20. For example, in the case of a persulfate etching solution based on (N)I4)zszOs 21
An example is a method using an aqueous solution having a concentration of about 240 g/l or less and carried out at a temperature of 20 to 35°C.

In the case of an etching solution based on ferric chloride, for example, F
eC1-(40°Be') 5.81', HCI(3
5wt%) 1.2A and water3. An example is a method in which an aqueous solution containing O1 is used at a temperature of about room temperature (25° C.) or lower.

In the case of chromic acid/sulfuric acid etching solution, e.g. CrL
240g/A'5Na2SO440,5g#, H2S
An example is a method using an aqueous solution having a concentration of about 04 (96%) 180 g/42 or less.

However, for example, alkaline etching solutions have the disadvantage of poor stability, persulfate etching solutions have the disadvantage that etched copper tends to precipitate from the aqueous solution, and ferric chloride etching solutions have the disadvantage of varying dissolved copper concentration. In the present invention, hydrogen peroxide/sulfuric acid etching solution has the disadvantage that the etching rate changes greatly, and in the case of chromic acid/sulfuric acid etching solution, it corrodes the resin of the laminate.
A sulfuric acid-based etching solution is most preferred from the viewpoint of solution management and pollution.

The etching method in the manufacturing method of the present invention is carried out using a spray etching machine, and the etching rate of the copper foil is preferably 0. Obcm/sec ~ 0.4 instant/sec, especially 0.03-
/second to 0.3ρ/second. If the etching speed is fast, the thickness of the remaining copper foil is likely to change due to a slight time lag, and if the etching speed is slow, it is not economical in terms of time and equipment.

In order to completely remove the copper foil on one side and leave a thin copper foil of the desired thickness on the other side using the spray etching machine of the present invention, a predetermined etching solution is usually used and the spray pressure or number of sprays used is adjusted. Instead, it is preferable to set the etching speed on both sides to be higher than the desired speed ratio, and in particular, it is preferable to change the number of sprays used in the direction parallel to the moving direction of the double-sided copper-clad circuit board to be etched, but not in the perpendicular direction. More preferably, in horizontal spray etching, the number of spray nozzles on the lower side is smaller than the number of spray nozzles on the upper side. For example, 54 spray nozzles are placed at the top and bottom in an area of 1 m long and 0.6 m wide, with 9 rows in the length direction (parallel to the direction of movement) and 6 rows in the width direction (direction perpendicular to the direction of movement). When the etching speed ratio between the upper surface and the lower surface is set to 271 in a spray etching machine in which rows of nozzles are arranged in a standard array, the upper side is in the standard array, the number of spray nozzles on the lower side is reduced to 4 rows in the longitudinal direction, and then,
An example is a method in which the speed ratio is adjusted to be larger than a desired value using spray pressure or the like. Note that etching is performed by standing the double-sided copper-clad circuit board vertically; in addition, conventional etching machines usually use a method in which the nozzle spray direction is as perpendicular to the surface of the laminate as it moves at a constant speed. However, in the case of the present invention, it is sufficient to uniformly spray the surface of the laminate, and it is also possible to use the spray at an angle of about 30° to 75°.

After cleaning the copper foil surface of the laminate treated with the etching agent described above, it is dried as appropriate, and a rust preventive agent or a peelable resin coating is applied to protect the copper foil surface.

Here, cleaning may be any known impurity removal method such as neutralization, acid washing, water washing, hot water washing, etc., taking into account the stabilizer and other components of the copper etching solution using hydrogen peroxide/sulfuric acid aqueous solution. Although it is selected as appropriate, it is usually preferable to perform neutralization → acid cleaning → (corrosion prevention or protective film coating).

After drying appropriately, the copper foil surface is protected with the rust preventive agent or peelable resin of the present invention. Examples of the rust preventive include known copper rust preventives, azole compounds such as benzotriazole, and those in which a surfactant or the like is used in combination as appropriate. Also, examples of removable resin include 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 Examples include general-purpose solvent-soluble resins such as molecular weight polystyrene; photoresist resin liquid, etc., and may be directly pressure-bonded to the cleaned copper foil surface, or further pressure-bonded to the rust-preventing surface as described above. Coat the copper foil surface.

〔Example〕

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

Example 1 Length 1020mm, width 600m+n, plate thickness 1.6mm,
Using a horizontal spray etching machine, a glass cloth-based epoxy resin laminate with nominal 18ρ copper foil (Nikko Gould Co., Ltd., TC foil) on both sides was etched with hydrogen peroxide/sulfuric acid etching solution (Mitsubishi Gas Chemical Co., Ltd., FES-6000). , l(, [12
=7. 'i'8w/v%, H2S04=11.7w/v
%) was used for etching under the following conditions.

・Etching conditions.

Next, after neutralization, acid washing, and water washing, a water-soluble rust preventive agent (
For example, use C, B, Bright (manufactured by Mitsubishi Gas Chemical ■), Coromin CB (manufactured by Kao Atlas ■, etc.) to prevent rust, and apply an eddy current film thickness meter (manufactured by Densoku Kogyo ■, Goomes Vortex). By measuring the thickness of the copper foil with an electric current type film thickness meter, model O3-1), the thin copper clad plates listed in Table 1 were continuously coated for 10 minutes.
One piece was manufactured.

Table 1 [Operations and Effects of the Invention] As is clear from the detailed description and examples of the invention,
According to the manufacturing method of the present invention, a single-sided thin copper-clad laminate in which the thickness of the silver foil is 18 mm or less can be easily manufactured, and it can also be manufactured with excellent copper foil thickness accuracy and copper foil peel strength. .

As a result, single-sided thin copper-clad laminates, which have heretofore been virtually difficult to manufacture, can be easily manufactured with high precision and at low cost, and are therefore of great industrial significance.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd.

Claims (1)

[Claims] A double-sided copper foil-clad circuit board made of copper foil and an electrical insulator is etched on both sides using a spray etching machine using a copper etching solution, and the thickness of the remaining copper foil on one side of the double-sided copper foil-clad laminate is determined. 10-75% of the original copper foil thickness
A method for manufacturing a single-sided thin copper foil-clad circuit board, characterized in that the copper foil on the opposite side is completely removed.