JP2003027260A - Method for producing metallic pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic pattern in which side etching in an etching stage is suppressed, and which has a high etching factor in a method for producing metallic pattern. SOLUTION: An etching resist pattern is formed on a metallic layer, and an electrically conductive metallic layer other than the resist pattern part is removed by etching using an etching solution to produce a metallic pattern. In this method for producing the metallic pattern, an etching solution containing fine grains is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal pattern, and more particularly to a method for manufacturing a fine and highly accurate metal pattern.

[0002]

2. Description of the Related Art Printed wiring boards, lead frames for IC / LSI, precision leaf springs, metal masks for vapor deposition, and solid masks for solder printing have an etching resist pattern formed on a metal layer and a metal layer other than the resist pattern portion is formed. Is manufactured by etching and removing with. In particular, in the method of manufacturing a printed wiring board, the subtract method, which is a method for removing a metal layer by etching, is the most technically established and is a very advantageous system in terms of cost.

With the recent miniaturization and multi-functionalization of electronic equipment, the density of printed wiring boards used inside the equipment has been increasing and the circuit patterns have been miniaturized. A printed wiring board having a fine pattern having a width of 90 to 130 μm and a pattern gap of 150 to 180 μm is manufactured. Further, due to further densification and finer wiring, circuits with conductor widths and conductor gaps of 70 μm or less are required. Along with this, demands for pattern accuracy and impedance are also increasing.

Currently, the most mainstream subtraction method is 70
When forming a fine pattern such as a pattern width of less than or equal to μm and a pattern gap, it is needless to say that the technical level and management level of all production lines need to be raised, but the etching process is a major point among them. Certainly. For example, liquid composition management, liquid spraying angle and strength on the substrate, etc. are important.

Further, one of the characteristics of the subtract method is side etching which advances from the side surface direction of the pattern in etching. Since the etching liquid enters the lower side of the overhanging portion of the etching resist pattern, side etching progresses and the etching factor increases. Even if optimum etching conditions such as liquid composition control and liquid spraying angle and strength to the substrate are adjusted to suppress the amount of side etching, the etch factor is 2-1.
There is a problem in that there is a large change in the range of 0 and the number of low-value conductor wires increases in the range of 2 to 10. In order to secure stable impedance and a highly accurate pattern, it is necessary to improve the etch factor without variation.

As described above, in the current subtraction method,
There is a limit in forming a fine patterned circuit with a high etch factor, and a semi-additive method has been proposed and put into practical use as a means for satisfying them. The semi-additive method proceeds through steps of catalysis, thinning by electroless copper plating, pattern formation, pattern copper plating, resist metal plating, plating resist stripping, and etching. In the case of the semi-additive method, the normal 18
5-10 μm, much thinner than copper foil thickness of 35 μm and 35 μm
Since the copper-clad laminate of copper foil is used as the starting material, the etching depth required for forming the conductor pattern can be remarkably small, which is very suitable for etching fine patterns. However, as described above, there are problems that the number of steps is large and labor is involved, and the cost is high, and that pattern plating is not uniform.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal pattern having a high etching factor by suppressing side etching in the etching step in the metal pattern manufacturing method.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above object, in a metal pattern in which an etching resist pattern is formed on a metal layer and the metal layer other than the resist pattern portion is removed by etching using an etching solution. It was found that this can be achieved by including fine particles in the etching solution.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The metal pattern manufacturing method of the present invention will be described in detail below.

Examples of the metal layer according to the present invention include copper, silver, aluminum, nickel, zinc, stainless steel, nichrome, and tungsten. Any metal that can be dissolved and removed using an etching solution is used. can do.

As the resist material used in the etching resist pattern according to the present invention, a commonly used liquid resist, a resist for electrodeposition coating or the like can be used, and a dry film one can also be used. These resist materials are variously seen as being different in negative type or positive type depending on the photosensitive area, sensitivity, exposure method, post-exposure and post-hardening treatment are necessary, and any resist material in the present invention can be used. Is also applicable.

The metal pattern formation according to the present invention is performed as follows. The exposed metal layer other than the resist pattern portion is removed by an etching process using an etching solution containing fine particles. At this time, an etching solution containing the fine particles is sprayed onto the metal layer provided with the etching resist layer by a shower. "Printed Circuit Technology Handbook"
The etching apparatus described in Japan Printed Circuit Industry Association, published in 1987, and published by Nikkan Kogyo Shimbun may be used.

The fine particles used in the present invention may be any fine particles that are not dissolved in the etching solution but are dispersed in the etching solution and can enter the lower side of the overhanging portion of the etching resist pattern. You can Specifically, silica, titanium oxide, aluminum oxide or the like is used.

The fine particles may be dispersed in the etching solution by simply mixing them, but it is preferable to disperse them by a dyno mill, a ball mill, a paint shaker or the like.
Moreover, you may use a dispersing agent together.

According to the etching method of the present invention, a metal pattern having a high etching factor can be obtained, which is considered to be based on the following principle. That is, in the metal layer portion which is not covered with the etching resist pattern, the etching progresses by the etching solution, but the etching progresses further in the depth direction by the action of the shower pressure. When the etching liquid contains fine particles, the fine particles physically scrape off the metal layer by the action of the shower pressure, so that the etching proceeds further in the depth direction. In addition, by the fine particles entering and depositing on the lower side of the overhanging portion of the etching resist pattern,
The contact between the etching solution and the metal layer is obstructed to suppress the progress of side etching. By these actions, a metal pattern having a good etching factor can be produced.

[0016]

EXAMPLES Examples of the present invention will be specifically described. The present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 170 mm × 256 mm × 0.2 mm (copper thickness 18 μm)
Rectangular rectangular double-sided copper clad laminate (manufactured by Mitsubishi Gas Chemical Co., Inc.,
CCL-E170), both sides of the negative type dry film (Asahi Kasei Co., Ltd., "Sunfort (film thickness 25um)")
Was laminated to form a dry film layer.

Next, a high-pressure mercury lamp light source device for printing having a suction film and a mask film having a pattern having a pattern width and a pattern gap of 20 μm is placed on the dry film layer; Unirec URM300 (USHIO INC.).
Was used for ultraviolet exposure.

Next, a 1% by mass sodium carbonate solution heated to 30 ° C. was sprayed and then washed with tap water to elute and remove the uncured dry film layer to form an etching resist pattern.

Next, 40 ° C., spray pressure: 2.0 kg /
Etching treatment was performed at cm2 to remove the metal layer other than the resist pattern portion by etching. The etching solution used at this time was 5% by mass of colloidal silica (Nihon Aerosil Co., Ltd. “AEROSIL-200” in ferric chloride solution).
CF ”(average primary particle diameter: 12 nm)) was added and exposed to an oscillation frequency of 38 kHz with an ultrasonic cleaner,
A liquid in which colloidal silica was uniformly dispersed was used.

As a result of observing the surface of the metal pattern obtained after etching, the pattern width and the pattern gap are 20 μm.
The pattern of m was reproduced well without pattern defects.
Further, when a cross section of a pattern having a pattern width and a pattern gap of 20 μm was observed, the pattern top width was 1
At 6 μm and a bottom width of 20 μm, a good pattern width was obtained without resist peeling.

Comparative Example 1 A metal pattern was prepared in the same manner as in Example 1, except that the etching solution used in Example 1 was a ferric chloride solution containing no fine particles.

As a result, when the surface of the obtained metal pattern was observed, spots where the etching resist layer was peeled off were found in some places, and disconnection and chipping were observed at those portions, and good metal pattern formation was not possible. It was Furthermore, as a result of cross-sectional observation of a pattern having a pattern width and a pattern gap of 20 μm, the pattern top width is 2 to 4 μm,
A bottom width of 20 μm and a thinning of the top are seen, and it is considered that the above-mentioned peeling of the etching resist is caused by the thin line width of the top and the weak adhesion to the resist.

Comparative Example 2 A metal pattern was prepared in the same manner as in Comparative Example 1 except that the etching conditions in Comparative Example 1 were weakened.

As a result, when the surface of the obtained metal pattern was observed, resist peeling did not occur, but a pattern residue was found in the pattern gap. Furthermore, as a result of cross-sectional observation of a pattern having a pattern width and a pattern gap of 20 μm, the pattern top width was 16 μm, but the bottom was connected to the adjacent pattern, and a good metal pattern could not be formed.

[0026]

As described above, according to the etching method using the etching liquid containing fine particles of the present invention,
When forming a metal pattern, it is possible to suppress side etching as compared with an etching method using an etching solution which is usually used, and it is possible to form a fine and highly accurate metal pattern.

Claims (2)

[Claims] 1. A metal pattern in which an etching resist pattern is formed on a metal layer and the metal conductive layer other than the resist pattern portion is removed by etching using an etching solution, wherein the etching solution contains fine particles. A method for forming a metal pattern. 2. The method for producing a metal pattern according to claim 1, wherein the fine particles are not dissolved in an etching solution.