JPH0225090A - Manufacture of single-sided thin copper foil-clad circuit board - Google Patents

Abstract

PURPOSE:To obtain an excellent single-sided copper foil-clad circuit board by a method wherein copper foils are formed in lamination on both sides of a releasing plastic film in such a manner that the copper foils sandwich the plastic film in between them from the outside, and two sheets of a single sided copper plated circuit board formed into one piece are subjected to an etching process and the ratio of thickness of the residual copper clad to that of an original copper plate is specified. CONSTITUTION:A single-sided copper foil-clad circuit board is formed of copper foils and an electrical insulator, where the foils and the releasing plastic film are formed in lamination in such a manner that the foils sandwich the film in between them from the outside. Two sheets of the single-sided copper-clad circuit board, temporarily pasted to the releasing prastic film into one piece, are subjected to an etching process using a copper etching solution to etch their both sides. And, the thickness of the residual copper foils is made to be 10-75% of that of the original foil. In this process, the etching process is performed as follows: the etching solution is a solution composed of hydrogen peroxide/sulfuric acid, persulfate, copper chloride, and the like as a main agent, and a stabilizing agent of the main agent, dissolution promoter of copper, and the like are added to the solution as an auxiliary agent: the concentration of an etching component is kept low; an etching speed kept low; and an etching temperature kept low. And, a laminated board is cleaned after the etching has been completed and dried up, and a rust preventive is applied onto the board, which is coated with a separable resin.

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;
A single-sided copper foil-clad circuit board such as a single-sided copper-clad film or a single-sided copper-clad sheet, in which the thickness of the copper foil suitable for use as the outermost layer in the production of high-density multilayer printed wiring boards is several times the thickness of the copper foil.
20p1 Thickness variation with respect to desired thickness is ±2, OJ
, aA or less, preferably ±1. This is a method for manufacturing a single-sided thin copper foil-clad circuit board having a temperature of less than 100 nm.

[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 foil used has a thickness of 1105 μm, 701.35 μm, 184 μm, and 184 μm by electrolytic method.
12. Copper foils such as 5-19- formed on carriers such as aluminum foils are also produced. or,
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 less than 35 mm have not been put into practical use.

When such copper foil is used for laminated molding, its thickness is 1
If it is thinner than 8ρ, it tends to wrinkle 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 manufacturing 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 photoresist. However, 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, it is recommended to use electrolytic copper foil with a thickness of less than 181 mm or a thickness of 20 mm on one side.
It has been virtually difficult to mass-produce single-sided thin copper foil-clad circuit boards coated with rolled copper foil of less than 10 mm.

[Means for solving problems]

As a result of intensive research into a method for manufacturing thin copper foil-clad circuit boards with high productivity that can be used as large-scale circuit boards, the present invention has been developed to eliminate differences in thickness accuracy due to differences in location or front and back sides to be extremely small even in large areas. discovered a method for manufacturing a thin single-sided copper-clad circuit board with a thickness of 0.3 au or less, and arrived at the present invention.

That is, the present invention is a single-sided copper foil-clad circuit board manufactured from copper foil and an electrical insulator, which is laminated in such a way that the copper foil is held on both sides of a plastic film for release. The two single-sided copper-clad circuit boards that have been molded and temporarily bonded to a release plastic film are then etched on both sides using a copper etching solution to determine the thickness of the remaining copper foil. This is a method for manufacturing a single-sided thin copper foil-clad circuit board characterized by having a thickness of 10 to 75%.

The configuration of the present invention will be explained below.

A single-sided copper foil-clad circuit board manufactured from the copper foil and electrical insulator of the present invention is a single-sided copper-clad circuit board manufactured by temporarily adhering a single-sided copper-clad circuit board to both sides of a releasable plastic film with the copper foil on the outside and integrating the single-sided copper foil-clad circuit board. As long as it is a copper-clad circuit board (hereinafter referred to as a "bonding board"), it may be integrated from the time of lamination molding or temporarily bonded and integrated after lamination molding, and is used for electronic and electrical materials. Various commercially available products can be used, but when applying the manufacturing method of the present invention, usually single-sided copper-clad films, sheets, and fiber-reinforced insulating resin laminates using copper foil with a nominal thickness of 18 or more are used. These include plates, metal core laminates, etc. The electrical insulator layer is made of polyimide resin,
Polyester resin films and sheets, thermosetting resins and heat-resistant thermoplastic resins, glass (E glass, D glass, S glass, quartz glass, etc.), ceramics (alumina, boron nitride, etc.), A porous film or sheet-shaped reinforcing base material using fibers, chops, etc. made of one or more types of heat-resistant engineering plastics such as wholly aromatic polyamide, polyimide, semi-carbon, fluorine resin, and other heat-resistant engineering plastics. It is manufactured using a combination of prepregs. In addition, due to the pressure of lamination molding, the copper foil surface of ordinary copper-clad laminates partially reflects the unevenness of the reinforcing base material, and for example, in the case of a glass woven base material, it has undulations of about 40 mm at a 40 mm pitch. However, it is mechanically precisely polished to have a fine unevenness of about 3JJM or less, but it is also possible to use one with the undulations removed.

The single-sided copper-clad laminate of the present invention is as described above, and is particularly preferably made of cellulose triacetate, polypropylene, poly-4-methylpentene-1, polyvinylidene fluoride, polytetrafluoroethylene, and other plastics. For this, a release plastic film with a surface roughening treatment (matte treatment) for adhesion is used, and the order of copper foil/prepreg/release plastic film/prepreg/copper foil is laminated and molded. It is preferable to use a bonding board made by temporarily bonding and integrating two single-sided copper-clad laminates, either as they are or after processing the outside shape as appropriate. A single-sided copper-clad circuit board is preferably used. When the thickness of the insulating layer is approximately 0.3 to 0.05 +++ m, it tends to curl due to the difference in thermal expansion coefficient between the copper foil and the insulating layer, and therefore it is difficult to perform etching using a normal etching machine. In the state of the bonded laminate, such curling does not occur at all, and there is virtually no penetration of the etching solution between the releasable plastic film and the single-sided copper-clad circuit board. be.

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, It is an aqueous solution containing auxiliary agents to control the condition of the etched copper foil surface, and can be carried out by strictly controlling the etching conditions using normal etching equipment. Compared to the etching solution used for normal etching, there are methods to keep the concentration of etching components low, methods to keep the temperature low, or the amount of contact of the supplied etching solution on the copper foil surface (in the case of spray method, the spray pressure and number of sprays). ) (In particular, make the spray nozzles in the direction perpendicular to the direction of movement of the substrate to be etched smaller, increase the number, and further increase the etching liquid spray angle of the nozzle from 30 to 30 degrees perpendicular to the substrate to be etched. It is preferable to perform the etching at a slower rate than usual by tilting the etching layer at an angle of about 75° or by appropriately combining these methods. In particular, it is preferable to use a method in which the concentration of the etching solution or the etching temperature is lower than usual.

When using hydrogen peroxide/sulfuric acid as an etching solution,
Usually, the concentration of hydrogen peroxide (H2O2) is 0.7~14w
/v%, the concentration of sulfuric acid (H, SO,) is 1 to 25 w/v%
The molar ratio of H20□/H,SO, is 0.2 to 1 and the temperature is 2.
It is desirable that the temperature be in the range of 0 to 55°C, and in order to produce a thin copper foil-clad circuit board with different thicknesses on both sides with particularly stable and high thickness accuracy, the concentration of H2O2 should be 2 to 6 w/v%,
The concentration of sulfuric acid is 3~11w/v%, the copper concentration is 30~60g/
1 with a temperature in 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. ; Glycol ethers such as polyethylene glycol; Nitrogen-containing organic cyclic compounds such as aminobenzoic acid, aminotetrazole, and phenylurea, and the like, and the amount is usually appropriately selected from the range of 0.1 to 5%.

In the case of a cupric chloride etching solution whose main ingredient is CuC]□, for example, CuC'12-28201.421b
C1(20'Be') 0.6gal was dissolved to make an aqueous solution Lgal (CuC1, 211.0170g
/j2. An example of this method is to use an aqueous solution having a concentration of about 19 w/v % (HCl (19 w/v % aqueous solution) or less) at a temperature of 30 to 40°C.

NLOIl, NH2Cl, CLI, NaClO2
, N114NO3, etc., in the case of a so-called "alkaline etching solution", for example, NH4OH3mol/4
2. NaCNaC102l0/A.

NH=C11mol#, N1JCOs 1mol/
j2. The concentration of NH4NO3 is about 1 mol/β or less, and the Cu concentration in the aqueous solution is 10 lb/gal (74
, 89g/j2) or less, by keeping the temperature at 30-45℃, or by keeping the etching temperature at 20-30℃ as a normal solution concentration.
An example is a method of keeping the temperature at about ℃.

(NH,), S20. For example, in the case of a persulfate etching solution based on (NH4)2320821b/g
A, 1 (method using an aqueous solution with a concentration of about 240 gz# or less and carried out at a temperature of 20 to 35°C is exemplified).

In the case of an etching solution based on ferric chloride, for example, F
eCIa (40°Be') 5.8j! , HCI(3
An example of a method is to use an aqueous solution containing 5 wt %) 1.2j2 and water 3.0β at a temperature below about room temperature (25° C.).

In the case of chromic acid/sulfuric acid etching solution, e.g. CrO+
240g/, f! 5Naz30440.5g/β, H
An example is a method using an aqueous solution having a concentration of about 2S04 (96%) 180 g/j2 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 preferably carried out using a spray etching machine, and the etching rate of the copper foil is preferably 0.01 ρ/sec to 0.01 ρ/sec. Ifm/sec, especially in the range of 0.03 JJ3/sec to 0.3 Js/sec.

If the etching speed is fast, the thickness of the remaining copper foil tends 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 obtain a copper foil of a predetermined thickness by spray etching, a method is generally used in which a predetermined etching solution is used and the etching speed on both sides is set within a desired speed range by adjusting the spray pressure or the number of sprays used.

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, including azole compounds such as benzo)IJ azole, and those in which a surfactant or the like is appropriately used in combination. In addition, examples of resins that can be peeled off include polyethylene, polypropylene, ethylene-propylene resin, ethylene-vinyl acetate resin, vinylidene chloride, polyacrylate copolymer, 1,2-polybutadiene resin,
Examples include polyester resin, other thermoplastic resin films, and photoresist films; general-purpose solvent-soluble resins such as paraffin wax, polyethylene wax, rosin, and low-molecular-weight polystyrene; and photoresist resin liquid, which are cleaned. It may be directly crimped onto the surface of the copper foil, or it may be further crimped onto the anti-corrosion treated surface to cover 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 1020++on x 1020mm and thickness 0.1mm
glass cloth base epoxy resin prepreg, 1050mm
X 1050mm, nominal thickness 18-copper foil (manufactured by Nikko Gould Co., Ltd., JTC treated electrolytic copper foil) and tetra-film
(manufactured by Du Pont), copper foil/prepreg/tetra film/prepreg/copper foil were stacked in this order and sandwiched between two mirror plates, and the weight was 30 kg/c [I! , 170° C. for 2 hours to produce a “conjugated board” in which 0.1 mm single-sided copper-clad laminates were temporarily bonded together via a film.

This bonded plate was etched using a horizontal spray etching machine using a hydrogen peroxide/sulfuric acid etching solution (manufactured by Mitsubishi Gas Chemical Co., Ltd., F
ES-6000,)! 2oz=7.78w/v%, H
Etching was performed under the following conditions using a 3-fold diluted solution of 2S04 = 11°7w/v%).

・Cu = 40g/β ・Etching speed for standard array: 0.18/sec.

Next, after neutralization, acid washing, and water washing, a water-soluble rust preventive agent (
For example, C, B, Bright (manufactured by Mitsubishi Gas Chemical),
It was treated with Coromin CB (manufactured by Kao Atlas Japanese Co., Ltd.) to prevent rust, and then dried.

Then, process the outside shape to 1000mm x 1000mm
After forming a conjugated plate of 0.2 mm, it is peeled off from the release film to a thickness of 0.0 mm.
Two 1 mm single-sided copper clad plates were used. Table 1 shows the results of measuring the thickness of the copper foil of this copper-clad board with an eddy current film thickness meter (Gumes eddy current film thickness meter, model O3-1, manufactured by Densoku Kogyo ■).

Example 2 A conjugated plate obtained in the same manner as in Example 1 was cut with a shear and heated to
30℃.

It was cut into six conjugated plates measuring 500 mm x 330 n++n.

After etching, washing, and drying for rust prevention in the same manner as in Example 1 using this externally processed bonding board, the copper foil was peeled off from the release film and had an average thickness of 8.8 cm and a thickness of 0.5 cm. 1
Twelve single-sided plates of mm in diameter were obtained.

At the time of peeling, we observed that the etching solution, cleaning solution, and anti-rust solution soaked into the surrounding area, but no penetration was observed.

Example 3 A copper foil with a nominal thickness of 18-0 (manufactured by Mitsui Kinzoku ■) with an adhesive of 40-thickness was layered on both sides of a polypropylene film with a thickness of 30ρ with the copper foil on the outside, and was placed on a hot roll at a temperature of 140°C for 2 hours. This was passed through with pressure applied for seconds to form a temporarily bonded conjugated sheet.

An adhesive-coated copper foil having a thickness of 8.8 mm was obtained in the same manner as in Example 1, except that this temporary adhesive bonding sheet was used.

[Operation and effects of the invention]

As is clear from the detailed description of the invention, Examples, and Comparative Examples, according to the manufacturing method of the present invention, a thin single-sided thin copper-clad insulating layer having a copper foil thickness of 181 mm or less is produced using a bonding plate. Two laminates can be installed at the same time without being contaminated by etching liquid, etc.
It is easy to manufacture and can also be manufactured with excellent copper foil thickness accuracy and copper foil peel strength.

As a result, an outer layer copper-clad single-sided board for a high-density printed wiring board or a high-density multilayer printed wiring board can be easily manufactured with high precision and at low cost, and therefore has extremely great industrial significance.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd.

Claims (1)

[Claims] A single-sided copper foil-clad circuit board made of copper foil and an electrical insulator, which is laminated and molded with the copper foil on both sides of a plastic film for mold release, with the copper foil on the outside. Using a copper etching solution, two single-sided copper-clad circuit boards are temporarily bonded and integrated into a plastic film.
A method for producing a single-sided thin copper foil-clad circuit board, characterized in that both sides are etched so that the remaining copper foil has a thickness of 10 to 75% of the original copper foil thickness.