JPH0156557B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a simple method for manufacturing a thick film fine pattern with high density and high reliability. Thick film fine patterns are required in fields such as small coils, high-density connectors, and high-density wiring that require high current values. For example, a wire winding method is normally used to manufacture coils, but this method makes it difficult to manufacture small coils and causes variations in the state of the windings. In addition, so-called printed coils made by etching 35 μm copper foil cannot obtain fine patterns because of side etching, and can only obtain patterns of 2 to 3 wires/mm at most, and this method is also difficult to manufacture small coils. It's difficult. However, with the miniaturization of motors in recent years,
There is a demand for the development of a fine coil having a fine pattern of 1/mm. In the present invention, after first forming a conductive paste pattern with a film thickness of 5 to 10 μm, a conductor is coated using a copper sulfate plating solution or a copper pyrophosphate plating solution at a cathode current density of 5 to 15 A/ ^dm2 . It has been discovered that a thick film fine pattern with high density and high reliability can be obtained by electrolytically plating the film. That is, in the present invention, after forming a conductive paste pattern with a film thickness of 5 to 10 μm on the circuit portion of a film substrate, a cathode current density of 5 to 15 A/cm is applied using a copper sulfate plating solution or a copper pyrophosphate plating solution. The present invention provides a method for producing a thick film fine pattern characterized by electrolytically plating a conductor under ^dm2 conditions. In the production of thick film fine patterns (for example, thick films of 20 to 50 μm with 5 lines/mm or more), the cathode current density of electrolytic plating is important, as shown in Figure 1.
When electrolytic plating is performed at a normal current density, thickening occurs in the width direction more than the film thickness, and the plating film thickness becomes uneven, making it difficult to obtain a thick film fine pattern. In order to solve this problem, the cathode current density of electrolytic plating is important;
20A/ ^dm2 is a preferable range, especially 5~
15 A/dm ² is preferred. Cathode current density is 3A/d
If it is less than m ² , thickening occurs in the width direction and the plating film thickness becomes non-uniform, and if it is more than 20 A/dm ² , it will cause burns. The method for manufacturing a thick film fine pattern of the present invention includes:
It may be formed only on one side of the film-like substrate, but
If necessary, it may be formed on both sides, and if it is formed on both sides, it is necessary to make holes in the film-like substrate and perform through-hole connections before forming the conductive paste. In the case of forming a plurality of patterns on one film-like substrate, it is preferable to form the patterns on both sides of the film-like substrate and connect them through through holes because it is easier to connect them. The film substrate used in the present invention includes:
All film-like materials such as polyester film, epoxy film, polyimide film, polyparabanic acid film, and triazine film can be used, but polyimide film, polyparabanic acid film, and triazine film are preferred from the viewpoint of flexibility and heat resistance. The film thickness of the film-like substrate is preferably as thin as possible in the sense of high density, but if it is too thin, workability will deteriorate, so the film thickness is preferably in the range of 5 to 50 .mu.m, particularly 10 to 25 .mu.m. In the present invention, the conductive paste pattern may be formed by screen printing or gravure printing, and the conductive paste for photoforming may be coated, exposed,
It may be performed through a developing process. The printing method does not produce such a fine pattern, but it is a simple process, and the photoforming method has a slightly complicated process, but it is easy to obtain a fine pattern. Conductive pastes basically consist of conductive particles such as silver or copper, a polymer binder, and a solvent. '' are common, and those with excellent plating properties, patterning properties, and heat resistance are preferred.
The preferred thickness of the conductive paste is 1 to 30 μm; if it is less than 1 μm, it will be difficult to achieve uniform plating, and if it is more than 30 μm, it will be difficult to obtain a fine pattern. In the present invention, after forming a pattern of conductive paste, it is more preferable to form a conductor on the conductive paste by electroless plating. The electroless plating film thickness is preferably 10 μm or less, particularly 5 μm or less in order to obtain a fine pattern. Any type of electroless plating may be used as long as it is a conductor, but copper is particularly preferred from the viewpoint of economy and conductivity. Any type of electrolytic plating may be used as long as it is a conductor, but silver, gold, copper, nickel, tin, etc. are preferred, and copper is particularly preferred from the standpoint of conductivity and economy. Examples of electrolytic plating for copper include copper cyanide plating, copper pyrophosphate plating, copper sulfate plating, and copper borofluoride plating, with copper pyrophosphate plating and copper sulfate plating being particularly preferred. The thickness of the plating film varies depending on the design value, and is preferably in the range of 10 to 50 μm. Further, in order to further improve reliability, after electrolytic plating, heat treatment or treatment such as providing a protective layer made of gold, tin, solder, or polymer is performed as necessary. EXAMPLES In order to further clarify aspects of the present invention, examples will be described below, but the present invention is not limited to the following examples, and various modifications are possible. Example 1 Polyimide film “Kapton” manufactured by DuPont
(film thickness: 25 μm), conductive paste “D-850” manufactured by Fujikura Kasei Co., Ltd. was screen printed on a 10 μm thick circuit portion, and heat treated at 150° C. for 30 minutes. Next, copper was electrolytically plated to a thickness of 20 μm at a cathode current density of 14 A/dm ² using a copper pyrophosphate plating solution manufactured by Hershyou Murata Co., Ltd. to form a film with a uniform thickness of 8 wires/mm.
A fine pattern was obtained. Example 2 Through-holes were drilled in the polyparabanic acid film "Tradron" (film thickness 25 μm) manufactured by Etsuo Chemical Co., Ltd., and polyamideimide obtained from m-phenylenediamine and trimellitic anhydride chloride was prepared.
A conductive paste consisting of 10 g, 90 g of fine silver particles with a particle size of 1.8 μm, and 25 ml of dimethylacetamide,
Gravure printing was performed on a 5 μm thick circuit portion and heat treated at 100° C. for 30 minutes. Thereafter, copper was electrolessly plated to a thickness of 3 μm using an electroless plating solution "CP-70" manufactured by Shipley Co., Ltd., and then a current density of 7 A/dm ² was applied to the cathode using a copper pyrophosphate plating solution manufactured by Hersho Murata Co., Ltd.
Electrolytic plating of copper with a thickness of 20 μm was performed under the conditions of
A fine pattern of mm was obtained. Comparative Examples 1-2 The same process as in Example 1 was carried out except that the cathode current density was changed as shown in Table 1. The results are shown in Table 1.

[Table] Comparative Examples 3 to 4 The same process as in Example 1 was carried out except that the film thickness of the conductive paste was changed as shown in Table 2. The results are shown in Table 2.

【table】 [Brief explanation of drawings]

FIG. 1 is a conductor growth curve obtained by electrolytic plating.

Claims (1)

[Claims] 1. A film thickness of 5 to 10 μm is applied to the circuit part of the film-like substrate.
After forming a conductive paste pattern, the conductor is electrolytically plated using a copper sulfate plating solution or a copper pyrophosphate plating solution at a cathode current density of 5 to 15 A/ ^dm2. 5 bottles/
A method for manufacturing a thick film fine pattern having a conductor of mm or more and film thickness of 20 μm or more.