JPH0360183A - Manufacture of circuit board covered with thin copper foil - 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] [Industrial Application Field] The present invention relates to a copper foil-clad laminate, a copper-clad film, and a copper foil-clad laminate manufactured from copper foil and an electrical insulator for manufacturing printed wiring boards on which electronic components are mounted. A thin copper foil-clad circuit board that is a copper foil-clad circuit board such as a copper-clad sheet or a reinforced copper foil, and has an average thickness of several LIM to 20-1 and a thickness variation of ±1.0- or less with respect to a desired thickness. This is the manufacturing method.

[Conventional technology and its problems]

Copper foil-clad circuit boards are manufactured by laminating copper foil and insulators, usually by lamination molding, etc., and the copper foil used has a thickness of 105mm by electrolytic method. rm170-135an, 1
Earn, 12-, etc. are mass-produced, and copper foils such as 5-19-, which are formed on carriers such as aluminum foil, are also produced. In addition, there is copper foil made by rolling, but due to the manufacturing method, the thinner the foil, the more expensive it becomes, and foils with a thickness of less than 35 mm are in the prototype stage and have not been commercially common. .

When such a KM is used for lamination molding, it is hardly put into practical use because if it is thin, it tends to wrinkle and the work of overlapping the copper foil with the insulator becomes extremely difficult. In addition, copper foil formed on a carrier such as aluminum foil improves this point, but it is expensive, and furthermore, the process of removing the carrier such as aluminum foil is required before forming printed wiring using copper foil. There was a question of necessity.

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, if the amount of copper foil removed by preliminary etching is increased to several times or more, or if 500×5
When manufacturing a thin copper-clad circuit board by etching a large area such as 00m+n square, the thickness of the remaining copper foil will vary greatly, making it impossible to manufacture a commercially viable thin copper-clad circuit board. There wasn't.

For example, in Japanese Patent Application Laid-Open No. 62-200796, an average thickness of 1
It is disclosed that an ultra-thin wJ foil-clad circuit board can be manufactured by reducing the thickness of copper foil to 12 or less by mechanically polishing, electrochemically polishing, or chemically etching copper foil having a thickness of 8 or more.

In this example 1 of JP-A-Sho, 340 mm x 340 mm
The corner copper foil with an average thickness of 18-
There is a description that the entire surface was etched with an etching solution consisting of mol/I / hydrochloric acid (6.6 mol/R) to obtain a thin copper foil with an average thickness of 10. However, according to studies by the present inventors, when using a commercially available spray etching method, when performing 6-etching on only five copper-clad laminates, the variation in average thickness is 3.5JE, and the variation in etching is ±4.8μ. It was so large that it corresponded to the amount. This means that the etching rate is approximately 0. The etching speed is as high as 5-/second, and a difference in etching time of 1 second appears as a difference in average thickness of 0.5-second, and this is due to the fact that the difference in effective contact time of the etching solution depending on the location is added. Furthermore, this tendency became more pronounced as the amount of etching was increased and as the amount of production was increased. Further, the other methods described in this publication, such as mechanical polishing and electrolytic polishing, were also similar and could not be commercialized. Furthermore, as described in the example of this JP-A-Sho, using an ordinary etching solution,
The surface of the remaining copper foil on a thin copper-clad circuit board whose entire surface was etched was extremely active, and if left in the air, it would rust in a short period of time.

[Means to solve the problem]

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 circuit boards, the present invention was developed to produce copper-clad circuit boards at a much slower speed than the conventional etching method. Etching the entire surface of the copper foil to remove 25 to 90% of the original thickness of the copper foil, and using cupric chloride/cupric chloride having a specific composition ratio as the copper etching solution.
We have discovered that a thin copper-clad circuit board with high thickness accuracy can be obtained by a method using an aqueous hydrochloric acid solution.

However, in this method, the surface of the copper foil was also highly active and had problems in terms of antirust effect, and lacked luster. After careful consideration of ways to improve this point, we found that
We have arrived at the present invention.

That is, in the present invention, a copper foil-clad circuit board manufactured from copper foil and an electrical insulator is etched using a copper etching solution of 0.01 to
The entire surface of the copper foil is etched at a rate of 0.3-/sec to remove 25-90% of the original copper foil thickness, and the thickness variation of the remaining copper foil is ±1. A method for manufacturing a thin copper foil-clad circuit board with a thickness of 0- or less, wherein first, using a cupric chloride/hydrochloric acid aqueous solution as the copper etching solution, etching is performed so that the remaining copper foil thickness is 1 cm 4 μ thicker than the desired thickness. This is a manufacturing method for thin copper foil-clad circuit boards, which consists of final etching or chemical polishing using a hydrogen peroxide/sulfuric acid aqueous solution. Cupric 0.25 ~ 3m
o 1 / , 1, hydrochloric acid 1 to 4 mol / ji! Within the range of , the hydrochloric acid concentration is at least ±0.3 mo of the predetermined concentration.
The etching temperature is controlled within 1/12 and the etching temperature is 25
The thin copper foil is made by controlling the temperature to within ±5°C within a predetermined temperature range of ~55°C, and immediately after the final etching or chemical polishing, the remaining copper foil surface is treated with a water-soluble rust preventive agent. This is a method for manufacturing foil-clad circuit boards.

Next, the configuration of the present invention will be explained.

The copper foil-clad circuit board manufactured from the copper foil and electrical insulator of the present invention uses a copper foil having an average thickness of 12 mm or more and a variation in thickness with respect to the average thickness of ±1.0 mm. If so, there is no particular limitation, and any of various commercially available products used for electronic and electrical materials can be used. Especially ■2-
In the case of the following thin copper foil clad laminates, the nominal thickness is 12 to 1
8-0 It is preferable to use a copper foil laminate. Examples of copper-clad laminates include single-sided or double-sided copper-clad films, sheets, fiber-reinforced insulating resin laminates, metal-core laminates, and multilayer shield plates with a printed wiring network formed on the inner layer. The electrical insulator layer can be made of polyimide resin, polyester resin film or sheet, thermosetting resin or heat-resistant thermoplastic resin, glass (E glass, D glass, S glass, quartz glass, etc.), ceramics. Porous materials using m-fibers, chops, etc. made of one or more types of heat-resistant engineering plastics (alumina, boron nitride, etc.), fully aromatic polyamides, polyimides, semi-carbons, fluorine resins, other heat-resistant engineering plastics, etc. These include those manufactured using prepreg in combination with a reinforced film or sheet-like reinforcing base material, and those manufactured by coating an iron, aluminum plate, etc. with an insulating adhesive or adhesive film. In addition, in the case of ordinary copper-clad laminates, due to the pressure of lamination molding, the copper foil surface partially reflects the unevenness of the reinforcing base material, for example, in the case of a glass woven base material, the pitch is about 3 to 4 mm at a pitch of about 0°4 mm. Although it has undulations, it is also possible to use a material in which the undulations are mechanically replaced with minute irregularities or removed. In addition, as a manufacturing method for copper-clad laminates or sheets using 12-16-0 thin copper foil, a 40-16-0 thin copper foil such as aluminum foil, which has a higher coefficient of thermal expansion than copper foil, is used between the copper foil and the mirror plate. A method of lamination molding by inserting a sheet of size 0- is suitable.

The second chloride/hydrochloric acid aqueous solution used in the first step of etching of the present invention contains cupric chloride and hydrochloric acid as essential components, and is used as an aid to control the state of the etched copper foil surface as necessary. It is an aqueous solution containing copper chloride (
The concentration of CuC122H20) is usually 0.25 to 3 mol
/ R, preferably 0.25 to 2 mol/l, hydrochloric acid (
)Ice) concentration is l, Q ~4 mol/j2
, preferably 1 to 3.6 mol/I! This range is used to perform high-precision full-surface etching within a practical range. Alcohols as auxiliary agents include monohydric alcohols such as methanol, ethanol, propatool, and butanol; dihydric alcohols such as ethylene glycol, propylene glycol, butanediol, and bentanediol;
Examples include trivalent or higher alcohols such as glycerin and pentaerythritol, and other additives include glycol ethers such as polyethylene glycol; nitrogen-containing organic cyclic compounds such as aminobenzoic acid, aminotetrazole, and phenylurea. be done.

Also, copper dissolves into the etching solution during etching, but the concentration of this dissolved copper is 5 to 65 g/j!
(0.08 to 1.0 mo! #ri, preferably 5
It is preferable to adjust it within the range of 0 g/l or less.

Etching is carried out using the cupric chloride/hydrochloric acid aqueous solution mentioned above, but this etching solution significantly reduces the etching speed compared to the hard etching used in normal pattern formation, and also This reduces the dependence on The etching rate used is in the range of 0.01-0.3 IIn/sec, more preferably in the range of 0.03-0.20-/sec. If the etching rate is faster than 0.3-/second, the difference in the amount of etching becomes large due to differences in etching processing time, component concentration, temperature, etc., which are smaller than the controllable range of etching conditions.

This appears as variations depending on the location of the copper clad plates, and variations in the average thickness when processing a large number of sheets, and a high-precision thin copper clad circuit whose thickness range is within ±1.0μ relative to the desired copper foil thickness. This is undesirable because it becomes difficult to manufacture the substrate, creates an extra burden on quality control, and increases the number of defective products. Furthermore, if the etching speed is slower than 0.0IE11/sec, etching takes a long time and is not practical.

Next, the hydrogen peroxide/sulfuric acid aqueous solution used in the final etching or chemical polishing of the present invention is hydrogen peroxide (H2O2).
concentration 0.3-3 mol/R, sulfuric acid (HiSD<>
At a concentration of 0.05 to 1.5 mol/j2 and a temperature of 25 to
Preferably, the temperature is 50°C and the copper concentration is in the range of 10 to 60 g/i.

The hydrogen peroxide/sulfuric acid aqueous solution preferably contains auxiliary agents such as a hydrogen peroxide stabilizer, a copper solubility promoter, and a brightening agent. Auxiliary agents include monohydric alcohols such as methanol, ethanol, propatool, and butanol; dihydric alcohols such as ethylene glycol, propylene glycol, phthanediol, and bentanediol; and trihydric alcohols such as glycerin and pentaerythritol.
Examples include alcohols having a higher alcohol content; glycol ethers such as polyethylene glycol; and nitrogen-containing organic cyclic compounds such as aminobenzoic acid, aminotetrazole, and phenylurea. It is added. This hydrogen peroxide/sulfuric acid aqueous solution has an etching solution composition when the molar ratio is H2SO4/H20□〉0.1. It is preferable to use a chemical polishing liquid composition, and when the molar ratio of a large excess hydrogen peroxide system is 12sO4/H2O2≦0.1, the composition becomes a chemical polishing liquid, and no auxiliary agent for imparting gloss is particularly required. Further, the thickness of the copper foil removed by final etching or chemical polishing is usually in the range of t to 4-, preferably 2.
-3- range.

The above etching methods are usually 1. It is appropriate to carry out spray erating 2, and it is carried out either horizontally or vertically.

In particular, when etching both sides of a large-area copper clad plate at the same time, it is preferable to set it vertically. Further, after etching is completed, it is preferable that the etching solution adhering to the surface of the copper-clad laminate is quickly removed. Usually the first
After the first step of etching is completed, water or a dilute acid aqueous solution is sprayed onto the surface of the copper foil and stopped, followed by a second step of etching or chemical polishing. In particular, when a chemical polishing liquid composition is used, cleaning is performed after acid cleaning to dissolve and remove the copper oxide film. Note that when a chemical polishing liquid composition is used in the second stage, a dipping method is also suitably used.

To remove a specified thickness of copper foil by etching,
A method is used in which the etching rate under predetermined etching conditions is measured and the etching time is set using this rate as a specific value within the above range. For example, if you are using a double-sided copper-clad board with copper foil of the same thickness on both sides, and you want to make both sides horizontal and the same thickness at the same time, you need to adjust the spray pressure as necessary so that the etching speed on both the top and bottom is the same. Adjust the etching speed by controlling the number of sprays, etc.
Depends on the method of etching for a predetermined period of time. Furthermore, in conventional horizontal etching machines, a method is adopted in which the jetting direction of the nozzle is as perpendicular as possible to the copper foil surface of the laminated board, which moves at a constant speed of several meters or less. In such cases, it is sufficient to uniformly spray the surface of the copper foil of the copper clad plate, and the spray nozzle may be used with the spray angle tilted by about 30° to 50°. In addition, for finishing etching or chemical polishing, the same method as the above-mentioned spray etching is used in terms of continuous processing with the first stage etching, but when using the above-mentioned chemical polishing liquid composition,
Methods such as immersion are also preferably used. In addition,
In the method of the present invention, it is necessary to extremely strictly control the amount of copper foil removed, so in addition to keeping the etching speed constant by adjusting the composition of the etching solution as described above, the effective contact time with the etching solution must also be controlled more strictly. It is preferable to be able to set it to .

The copper foil surface of the laminate that has been treated with the above two-step etching or chemical polishing agent is cleaned, dried appropriately, and a rust preventive agent 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 cupric chloride/hydrochloric acid aqueous solution. After pickling, water washing, or hot water washing, neutralization treatment at 20 to 50°C with an aqueous solution of 1 to 5 wt% of sodium carbonate, the rust preventive agent may be a known copper rust preventive agent, such as a copper rust preventive agent. , azole compounds such as benzotriazole at 0.01 to 1
It is preferable to carry out the immersion treatment at 20 to 50° C. in an aqueous solution containing 20 to 50° C., containing a surfactant and the like as appropriate.

In addition, after the rust prevention treatment, heat-removable resins such as polyethylene, polypropylene, ethylene-propylene resin, ethylene-vinyl acetate resin, vinylidene chloride, polyacrylate copolymer, 1,2-polybutadiene resin, polyester resin, etc. Plastic resin films and photoresist films; general-purpose solvent-soluble resins such as paraffin wax, polyethylene wax, rosin, and low molecular weight polystyrene; photoresist resin liquid can also be applied to cover the body foil surface by pressure bonding, etc. preferable.

As described above, the cupric chloride/hydrochloric acid aqueous solution of the present invention is characterized by significantly lowering the hydrochloric acid concentration compared to conventional solutions, and mainly controlling the hydrochloric acid concentration.

This point will be explained with reference to the attached drawings.

〔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 Using 10 glass cloth base epoxy resin laminates, each of which was 700 x 1020 mm, 1.6 mm thick, and coated on both sides with copper foil with an average thickness of 15 mm and treated with a low profile on one side, an average copper foil thickness of 9 mm was used. A thin copper-clad circuit board was manufactured.

The copper foil thickness range of the double-sided trunk board used was 15.0μ on average,
Maximum 15. ! za+, minimum 14.5-, variation ±0
．． The surface unevenness of the copper foil measured by the needle was 3.6 to 4.3 tnh.

In the first stage etching, a horizontal etching machine was used, the following copper chloride etching solution was used as the copper etching solution, and the remaining copper foil was etched to a thickness of 12-
It was etched so that

As a second stage etching (finish etching), the following hydrogen peroxide/sulfuric acid aqueous solution was used to make a double-sided hollow board with an average thickness of 9 mm.

Then, it was immersed in a 5% Na2Co aqueous solution at room temperature for 30 seconds, then immersed in a 0.3% concentration benzotriazole aqueous solution at 40°C for 30 seconds, and dried with hot air at 100°C for 30 seconds.

For all 10 thin copper clad plates obtained, the copper foil thickness was measured at any point within 18 rectangles obtained by dividing the thickness of the copper foil into three equal parts vertically and horizontally, and the average 8.9
μ, Maximum 9.5-1 Minimum 8.6- The variation with respect to the average thickness is ±0.6-1 The variation with respect to the desired thickness is ±
0.5-, and 95% of the measurement points are 8.6-9.4JJ
The surface roughness was in the range of 0 m, the surface unevenness was 2.5 to 3.5-1, and the surface gloss was 85.

Further, the obtained thin copper clad plate was held at 25° C. and 60% RH for 30 hours, but no rust was observed.

Example 2 In Example T1, second stage etching (chemical polishing)
The procedure was the same except that it was performed as follows.

・Ennanku streak U, U4EI+/sec.

The obtained thin copper clad plate was measured in the same manner as in Example 1, and the average copper foil thickness was 8.9. cm, maximum 9.4 blood, minimum 8.6-, variation in average thickness is ±Q, 5JI
n, the variation with respect to the desired thickness is ±0.4-,
95% of the measurement points were in the range of 8.8-9.2-, the surface unevenness was 2.0-3.0-1, and the surface gloss was 211.

Further, the obtained thin copper clad plate was held at 25° C. and 60% RH for 30 hours, but no rust was observed.

Comparative Example 1 In Example 1, a 9-thin copper foil circuit board was manufactured using the cupric chloride etching solution used in the first step under the following conditions.

Next, it was immersed in a 0.01-0.5% HCI aqueous solution, a 3% H,SO, aqueous solution, and a 5% Na2Co3 aqueous solution for 30 seconds each at room temperature, followed by a benzotriazole aqueous solution with a concentration of 0.3%. 40℃ for 30 seconds and 100℃
It was dried with hot air at ℃ for 30 seconds.

The obtained thin copper clad plate was measured in the same manner as in Example 1, and the average copper foil thickness was 8.9-1, maximum 9.4-1, minimum 8.
．． 6-, the variation with respect to the average thickness was ±0.5-1, the variation with respect to the desired thickness was ±0.4-1, the surface unevenness was 3.6-4.8-1, and the surface gloss was 1O15. .

Furthermore, when the thin copper clad plate was maintained at 25° C. and 60% RH, spotty rust appeared after 24 hours, and the storage stability was somewhat insufficient.

[Operation and effects of the invention]

As is clear from the detailed description of the invention, examples, and comparative examples, the present invention performs etching using a cupric chloride/hydrochloric acid aqueous solution at a much slower rate than conventional etching, followed by final etching or chemical polishing. By doing this, a thin copper foil-clad circuit board with extremely high thickness accuracy, excellent anti-corrosion effect, and high luster and high commercial value can be obtained, and its industrial significance is extremely large. .

Claims (1)

[Claims] 1. A copper foil-clad circuit board made of copper foil and an electrical insulator is etched over the entire surface of the copper foil at a rate of 0.01 to 0.3 μm/sec using a copper etching solution. A method for producing a thin copper foil-clad circuit board in which 25 to 90% of the original copper foil thickness is removed and the thickness variation of the remaining copper foil is within ±1.0 μm with respect to the desired thickness, As the copper etching solution, first,
A thin copper foil made by etching using a cupric chloride/hydrochloric acid aqueous solution so that the remaining copper foil thickness is 1 to 4 μm thicker than the desired thickness, and then final etching or chemical polishing using a hydrogen peroxide/sulfuric acid aqueous solution. Manufacturing method for stretched circuit boards. 2 Etching with the cupric chloride/hydrochloric acid aqueous solution includes cupric chloride 0.25 to 3 mol/l and hydrochloric acid 1 to 4 mol/l.
l, the hydrochloric acid concentration is at least ±0.3 of the predetermined concentration.
The etching temperature is controlled within mol/l and the etching temperature is 25%.
2. The method for manufacturing a thin copper foil-clad circuit board according to claim 1, wherein the temperature is controlled within ±5°C within a range of 55°C. 3. The method for manufacturing a thin copper foil-clad circuit board according to claim 1, wherein the remaining copper foil surface is treated with a water-soluble rust preventive agent after the final etching or chemical polishing.