JPH0222896A - Manufacturing method for double-sided thin copper foil-clad circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a double-sided copper foil-clad laminate made of copper foil and an electrical insulator for manufacturing printed wiring boards on which electronic components are mounted;
A double-sided copper foil-clad circuit board such as a double-sided copper-clad film or a double-sided copper-clad sheet, the thickness of which is several p to 20 ux+%, and the variation in thickness with respect to the desired thickness is ±2.0 p or less, preferably ±1.0- The following is a method for manufacturing a double-sided copper foil-clad circuit board in which the thicknesses of the copper foils on both sides are different.

[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 is made by electrolytic method with thicknesses of 105p, 70p, 35p, 118p, 1.
2p etc. are mass-produced, and copper foils such as 5cm, 9E11, etc. formed on carriers such as aluminum foil 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 35 mm or less have not been put to practical use.

When such copper foil is used for laminated molding, its thickness is 1
If it is thinner than 8p, 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.

Another known method is to pre-etch a copper foil-clad circuit board with an etching solution such as copper chloride or iron chloride in the printed wiring board processing process, polish the copper foil, and then use it in the printed wiring board manufacturing process. However, it has not been 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 an electrolytic copper foil with a thickness of less than 18 cm or a thickness of 20 p on one side.
A rolled copper foil of less than
Double-sided boards coated with copper foil, such as those used in POWs, were also virtually difficult to mass produce.

[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 etches 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 to remove the remaining portion of at least one side of the double-sided copper foil-clad laminate. A method for producing a double-sided thin copper foil-clad circuit board in which copper foils of different thicknesses are adhered to both sides, characterized in that the thickness of the copper foil remains 10 to 75% of the original thickness of the copper foil. Yes, the thickness of the copper foil on the original double-sided copper foil-clad circuit board is 18J, aR or more, and the thickness of the remaining copper foil on at least one side is 3 to 15P, and the thickness of the copper foil on the original double-sided copper foil-clad circuit board is 3 to 15P. A double-sided thin copper foil-clad laminate with copper foils of different thicknesses bonded to both sides, characterized in that the number of spray nozzles used for etching arranged on both sides of the double-sided copper foil-clad laminate, which is a substrate to be etched, is varied. This is a method of manufacturing circuit boards.

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 8- or more and changing the thickness of the copper foil on each side as necessary. For example, a multilayer shield plate formed with 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, due to the pressure of lamination molding, the copper foil surface of a normal copper-clad laminate partially reflects the unevenness of the reinforcing base material, and for example, in the case of a glass woven base material, it has a waviness of about 4JU at a pitch of about 40x. However, it is also possible to use a material whose undulations have been precisely polished mechanically.

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 (
(spray pressure or number of sprays in case of spray method)
It is preferable to perform etching at a slower rate than usual by reducing the etching rate or by appropriately combining these methods, and in particular, a method in which the concentration of the etching liquid or the etching temperature is lower than usual is preferred.

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 (H2SO4) is 1-25IIl/
The molar ratio of '202/H2S04 in v% is 0.2
-1 and the temperature is preferably in the range of 20 to 55 °C,
In particular, in order to stably manufacture thin copper foil-clad circuit boards with different thicknesses on both sides with high thickness accuracy, the concentration of -H202 should be 2 to 2.
6w/v%, sulfuric acid concentration 3-11W/v%, copper concentration 3
It is preferable to select from a range of 0 to 60 g/12 and a temperature 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, etc. are exemplified, 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 CuCl2, for example, CuC1,"2) 1201.421b and II
cI (20°13e') Q, 5gal is dissolved to make 1gal aqueous solution (CuC1□・2HJ 17
An example of a method is to use an aqueous solution having a concentration of 0 g/j' or less (an aqueous solution of HCI 19 w/v%) or less at a temperature of 20 to 40°C.

NH4OH, NH4Cl, Cu, NaClO2, N
In the case of a so-called "alkaline etching solution" which is an aqueous solution containing H4NO3, for example, NH4OH3mol/CNaC.
lO210mol/β, NH, C11mol/I! ,
NH4HCO31mol/1, NH4NO31m0
The concentration of Cu in the aqueous solution is set to below about 1/β, and the Cu concentration in the aqueous solution is 10
lb/gal (74.89 g or less, temperature 30
Examples include a method of maintaining the etching temperature at ~45 DEG C., or a method of setting the etching temperature to about 20 DEG to 30 DEG C. as a normal solution concentration.

(N)I4) In the case of a persulfate etching solution based on 2320B, for example, (NH<)2szOs 21b
An example is a method using an aqueous solution having a concentration of about 240 g/f or less and at a temperature of 20 to 35°C.

In the case of etching liquid based on ferric chloride, 40°B
To the ferric chloride solution of e', add 35% HCI 2 (1-1v
Using a solution containing 1% o or a solution diluted with water, 20
An example is a method performed at ~35°C.

In the case of chromic acid/sulfuric acid etching solution, for example Cr0a
240g/β, Na2S0. 40.5g/I!
An example is a method using an aqueous solution having a concentration of about 180 g of H2SO4 (96%) 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. However, in the case of chromic acid/sulfuric acid etching solution, there is a disadvantage that the etching rate changes greatly due to the use of etching solution. Furthermore, in the case of chromic acid/sulfuric acid etching solution, there is a disadvantage that it attacks the resin of the laminate. Therefore, in the present invention, hydrogen peroxide/sulfuric acid etching solution
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 0.03. cm/sec to 0.3 p/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 copper foils with different predetermined thicknesses using the spray etching machine of the present invention, usually a predetermined etching solution is used and the spray pressure or number of sprays used is adjusted to keep the etching speed on both sides within the desired speed range. Although a method of setting a desired speed ratio can be used, it is preferable to change the number of sprays used in the direction of movement of the double-sided copper-clad circuit board to be etched, but not in the perpendicular direction. In horizontal spray etching, it is preferable to adjust the number of spray nozzles on the lower side to be smaller than the number of spray nozzles on the upper side. For example, place 36 spray nozzles on the top and bottom in an area of 1 ms long and 0.6 m wide, with 9 rows in the length direction (parallel to the direction of movement) and 4 rows in the width direction (direction perpendicular to the direction of movement). In a spray etching machine with nozzles arranged in a standard or quasi-array, the etching speed ratio between the top surface and the bottom surface was set to 4.
/3, the upper side has a standard arrangement, the lower side has 6 rows of spray nozzles in the length direction and 4 rows in the width direction, and then the speed ratio is adjusted more precisely by adjusting the spray pressure, etc. Also, a double-sided copper-clad circuit board used for etching, for example, one with 35IjM electrolytic copper foil on one side and 18p electrolytic copper foil on the other side, is used, and both sides are etched at the same rate; A method in which a removable protective film such as a plastic film is formed on the entire surface or especially around the periphery of one side using a copper-clad circuit board, and only one side is etched. Etching machines usually use a method in which the spray direction of the nozzle is as perpendicular as possible to the surface of a laminate that moves at a constant speed, but in the case of the present invention, the spray is applied uniformly to the surface of the laminate. It is also possible to use it at an angle of about 30° to 50°.

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 rust preventive agents include known copper rust preventive agents, azole compounds such as benzotriazole, and those in which surfactants and the like are appropriately used in combination. 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 molecular weight polystyrene general-purpose solvent-soluble resins such as; examples include photoresist resin liquid, etc., and can be directly pressure-bonded to the cleaned copper foil surface, or further pressure-bonded to the rust-proofed surface as described above. Cover the 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 1 600 x 1000 mm, plate thickness 1.6 mm, nominal 1
Using a horizontal spray etching machine, a glass cloth base epoxy resin laminate with hc+n copper foil (Nikko Gould Co., Ltd., TC foil) on both sides was coated with hydrogen peroxide/sulfuric acid etching solution (
Manufactured by Mitsubishi Gas Chemical ■, product name: FBS-6000, H2O
2=7.78w/v%, H2SO1=11.7w/v
%) was used for etching under the following conditions.

Next, after neutralization, acid washing, and water washing, a water-soluble rust preventive agent (
For example, use C1B, Bright (manufactured by Mitsubishi Gas Chemicals), Colomin CB (manufactured by Kao Atlas, etc.), and use an eddy current type film thickness meter (manufactured by Kagosai Kogyo 91, Goomes eddy current type). By measuring the thickness of the copper foil with a 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.

Example 2 600x1000mm, plate thickness 1.6mm, one side nominal thickness 50. Using the same etching machine as in Example 1, a glass cloth base epoxy resin laminate with U electrolytic copper foil and a nominal 18p electrolytic copper foil on the opposite side was used, except that the spray nozzles were placed in the standard arrangement on both the top and bottom. Table 1 shows the results of etching under the same conditions and measuring the rust prevention and copper foil thickness in the same manner.

Table 1 Thin copper-clad laminates having different thicknesses can be easily produced, and those with excellent copper foil thickness accuracy and copper foil peel strength can also be produced.

As a result, thin copper-clad laminates having different thicknesses, which have been virtually difficult to manufacture in the past, can be easily manufactured with high precision and at low cost, and this has extremely great industrial significance.

Patent applicant Mitsubishi Gas Chemical Co., Ltd. agent (9070) Patent attorney Sadafumi Kobori [Operations and effects of the invention]

Claims (1)

[Claims] 1. A double-sided copper foil-clad circuit board made of copper foil and an electrical insulator is etched using a spray etching machine using a copper etching solution to remove at least one side of the double-sided copper foil-clad laminate. The thickness of the remaining copper foil is 10 to the thickness of the original copper foil.
A method for manufacturing a double-sided thin copper foil-clad circuit board in which copper foils of different thicknesses are adhered to both sides, characterized in that 75% of the copper foil is left unused. 2. The thickness of the copper foil of the double-sided copper foil-clad circuit board is 18 μm or more, and the thickness of the remaining copper foil on at least one side is 3 μm.
2. A method for manufacturing a double-sided thin copper foil-clad circuit board having copper foils of different thicknesses bonded to both sides according to claim 1, wherein the copper foils have a thickness of 15 μm. 3. Copper of different thicknesses according to claim 1, characterized in that the number of spray nozzles used for etching arranged on both sides of the double-sided copper foil-clad laminate, which is the substrate to be etched in the spray etching machine, is varied. A method for manufacturing a double-sided thin copper foil-clad circuit board with foil bonded to both sides.