JPH0649679A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To enhance the adhesive strength between a plating pattern and a film and to enable the formation of a wiring pattern with sufficient dimensional stability by electrodepositing lusterless Ni and transferring the electrodeposit to an insulating substrate consisting of polymide, etc., in an electroforming method. CONSTITUTION:An metallic substrate 1 such as stainless steel is degreasing- treated and after washed in hot water and cold water, a photoresist 2 is applied on the metallic substrate 1 and is dried. The photoresist 2 is exposed 3 by a pattern 4 for exposure and developed to form a metal-exposed surface 5 on the metallic substrate 1. Thereafter, Ni-plating is carried out in a lusterless Ni-plating bath such as a sulfamic acid bath to form the electrodeposit 6. Then, the electrodeposit consisting of Ni is transferred on the insulating substrate 8 consisting of polyimide resin by using a thermo-compression bonding type laminater 7. Further, after the Ni electrodeposit obtained on the substrate is subjected to the activated treatment, a gold-plated layer is formed by the electroless gold plating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to photofabrication, and more particularly to a method for forming a fine pattern of metal for an electronic device by an electroforming method.

[0002]

2. Description of the Related Art A chemical resistant coating is formed on a metal substrate in a predetermined pattern to partially expose the metal surface, and then the exposed metal surface is plated with a metal such as nickel or copper. Various techniques for depositing and processing a metal material into a predetermined shape have been conventionally studied, and these are called photofabrication and electroforming. As a representative document regarding this technology, “illustrated photofabrication” (Takao Hashimoto, Sogo Denshi Shuppan (198)
6)) etc.

The electroforming method will be described with reference to the drawings. As shown in FIG. 2A, first, a metal substrate 21 to be processed is prepared, and pretreatment such as degreasing treatment is performed.
For this, an alkaline degreasing agent, an organic solvent or the like is usually used. These degreasing agents are used to remove the rust-preventive coating formed on the surface of the metal substrate or the oils and fats attached to the surface, and then the degreasing agent on the metal substrate is removed in a water washing step. Next, the photoresist 22 is coated on the metal substrate 21 and dried. As shown in FIG. 2B, using the exposure mask 24 on which a predetermined pattern is formed,
Exposure 23 is performed with ultraviolet light or the like, and development is performed with a developing solution.

Further, heat treatment is performed to improve the film strength of the photoresist 22 and the adhesion to the substrate. Figure 2 (c)
The metal substrate on which the predetermined pattern shown in is formed is immersed in a bright plating solution, and nickel is electrodeposited to a predetermined thickness on the exposed metal surface 25 of the opening of the resist pattern. As shown in FIG. 2D, a bright nickel plating pattern 26 is attached to the surface of the substrate 21. After that, the plating pattern 26 is separated from the substrate 21 or transferred to a resin or the like by a transfer method, and as shown in FIG. 2E, holes or slits corresponding to the resist pattern are formed on the metal. A product 27 such as a plate or a metal laminated film is obtained. After that, if necessary, electroless gold plating or electroless palladium plating etc. is performed, and the predetermined dimension inspection,
After a visual inspection, they are shipped as products.

[0005]

A typical example of the above electroforming product is an outer blade of an electric razor,
There are a mesh, a filter, a laminated film on which a conductive pattern is formed, and the like, which are industrially mass-produced by the process shown in FIG.

A problem of the transfer method by the electroforming process is that the adhesion strength between the plating pattern and the film is not sufficient, and when it is used as a material for a printed circuit board or the like, a conventional film is sputtered with a conductive metal. There is a problem that the reliability is remarkably reduced as compared with a product obtained by electroplating a product into a two-layer film or a film obtained by casting a resin on a conductive metal to form a two-layer film. . Further, there is a problem in that the dimensional stability is significantly inferior to the above materials because of transfer via an adhesive.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plating pattern and a film by using a plating method having good adhesion between the plating pattern and the film when transferring the film. The object of the present invention is to provide a method by which the adhesion strength of (1) can be made sufficient, and as a result, an ultrafine pattern can be easily formed. Also,
It is an object of the present invention to provide a method in which a polyimide substrate is used as a transfer substrate to have sufficient heat resistance, and as a result, a wiring pattern having good dimensional stability can be easily formed.

[0008]

The present invention has been completed as a result of various studies on a method of transferring a metal electrodeposited by electroforming to a substrate by a transfer method to form an ultrafine pattern. Yes, by transferring the electrodeposit formed by matte nickel plating by the transfer method, it is possible to form a fine pitch pattern similar to the conventional transfer method, and further, the adhesion strength with various substrate films It is possible to obtain an improved product as compared with the conventional plating method.

That is, according to the transfer method of the present invention, at least a step of coating a resist on a substrate, a step of drying the coated resist, and a mask on which a predetermined pattern is formed are used to form a pattern on the substrate. In a transfer method comprising a step of exposing, a step of plating the substrate through a developed resist, and a step of transferring a predetermined pattern plated on the substrate to an insulating heat resistant resin, the substrate plating is performed. This is a method characterized by performing dull nickel plating and forming the substrate to be transferred entirely from polyimide, which improves heat resistance and lowers the dielectric constant. When gold or palladium plating is performed on the surface of a metal such as copper as a conductive pattern, nickel plating needs to be performed as a barrier layer in advance, whereas the electrodeposit obtained by the present invention is nickel. Because of this, direct gold plating is possible, and also in the surface treatment step, the process can be simplified as compared with the method by electroless plating.

[0010]

In the method of the present invention, since the matt nickel plating is used for the transfer plating, the adhesion strength with the substrate resin is remarkably improved, and the heat resistance is improved because all the resins are made of polyimide resin. As a result, it is possible to form a highly reliable ultrafine pitch pattern. In addition, since nickel plating does not require plating of the barrier layer, direct electroless gold plating or noble metal plating such as electroless palladium plating can be performed compared to the conventional method, which simplifies the process. Be converted.

[0011]

EXAMPLE Next, an example of forming a predetermined metal pattern on an insulating heat-resistant resin substrate by the method of the present invention will be described. As shown in FIG. 1 (a), after a metal substrate 1 such as stainless steel is degreased with an alkali or an organic solvent, it is washed with hot water and then washed with water, and then a mixture of casein and dichromate is formed on the metal substrate. The photoresist 2 is coated and dried.

As shown in FIG. 1B, the exposure pattern 4 is formed.
Then, the photoresist 2 is exposed 3 and the exposed surface 5 of the metal is formed on the metal substrate by development as shown in FIG. Thereafter, as shown in FIG. 1D, nickel plating is performed in a dull nickel plating bath such as a sulfamic acid bath to form an electrodeposit 6. Then, as shown in FIG. 1E, a thermocompression-bonding type laminator 7 is used to transfer an electrodeposit made of nickel onto an insulating substrate 8 made of a polyimide resin.

Further, after activating the nickel electrodeposit on the obtained synthetic resin substrate, a gold plating layer is formed by electroless gold plating. Example 1 A metal substrate made of stainless steel having a thickness of 0.15 mm was degreased with a 10 wt% sodium hydroxide aqueous solution at a liquid temperature of 60 ° C., and then washed with hot water and water to obtain a water-soluble colloid system ( A photoresist of casein + dichromate) is applied and dried at 70 ° C. for 15 minutes. At this time,
The viscosity of the photoresist was adjusted so that the film thickness after drying was 6 μm.

Further, 2.0 kW is formed on the formed photoresist film through an exposure mask having a predetermined pattern.
Was exposed for 100 seconds by the ultra-high pressure mercury lamp, and the photoresist after exposure was spray-developed with warm water.

Next, using a plating bath having the following composition, the composition of the plating bath: Nickel sulfate 320 g / l Nickel chloride 45 g / l Boric acid 30 g / l Sulfuric acid was added to adjust the pH to 2 Current density 6 A / dm ² , bath Plating thickness 25μ at 60 ℃
m matte nickel plating was performed. The surface roughness Ra of the obtained matte nickel was 217.7 nm.

Then, using a thermocompression-bonding type laminator, the resulting electrodeposit was formed on a polyimide resin thin film having a thickness of 25 μm to form a thermoplastic polyimide layer having a thickness of 30 μm. 350 ° C, manufactured by
Transfer was performed at 2.5 kg · mm ⁻¹ for 30 seconds.

The adhesion strength of nickel on the obtained polyimide substrate was measured by a tensile test in the horizontal direction. The adhesive strength was 1.68 kg · mm ⁻¹ . On the other hand, the nickel plating obtained by bright plating has a surface roughness Ra of 2
It was 5.5 nm, and the adhesive strength was 1.28 kg · mm ⁻¹ .

[0018]

As described above, in the transfer method of the present invention, when a metallic substrate on which a predetermined resist pattern is formed is plated with dull nickel, the resin is transferred to the insulating heat-resistant resin substrate for transfer. The adhesion strength between the substrate and the matte nickel plating is remarkably improved, and the reliability as an electronic circuit base material is remarkably improved. Further, the insulating heat resistant resin has improved strength after transfer regardless of whether it is an adhesive type or a thermoplastic resin type. In addition, since it becomes possible to form an ultrafine pattern and nickel is formed by electrodeposition, barrier plating is not required and the process can be simplified.

[Brief description of drawings]

FIG. 1 is a process drawing of an example of a transfer method of the present invention.

FIG. 2 is a process drawing for explaining electroforming.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal substrate, 2 ... Photoresist, 3 ... Exposure, 4 ... Exposure pattern, 5 ... Exposed metal surface, 6 ... Electrodeposited material, 7 ... Thermocompression-bonding type laminator, 8 ... Insulating substrate, 9 ... Gold plating layer,
21 ... Metal substrate, 22 ... Photoresist, 23 ... Exposure,
24 ... Exposure mask, 25 ... Exposed metal surface, 26 ...
Plating pattern, 27 ... Product

Claims (4)

[Claims] 1. An electrodeposition product deposited in an electrodeposition bath is transferred onto an insulating substrate on a portion of the conductive substrate on which the insulating substance pattern is not formed where the insulating substance pattern is not formed. A method of forming a fine pattern, which comprises depositing matte nickel and transferring the deposit onto an insulating substrate. 2. The fine pattern forming method according to claim 1, wherein gold plating or palladium plating is performed on the transferred electrodeposit. 3. The method for forming a fine pattern according to claim 1, wherein the insulating substrate has a heat resistant adhesive layer on a heat resistant insulating film. 4. The method for forming a fine pattern according to claim 3, wherein the heat-resistant adhesive layer is made of a thermoplastic polyimide resin.