JPH0154874B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a 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 usually 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 a fine pattern due to side etching, and only 2 to 3 coils/mm are etched at most.
This method also makes it difficult to manufacture small-sized coils. 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. The present invention first forms a thin film conductor with a thickness of 0.1 to 10 μm, and then thickens it by electrolytically plating it using 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 a high linear density of 5 lines/mm or more and high reliability can be obtained. That is, in the present invention, on a thin film conductor pattern formed by applying a mask method or an etching method to a thin film conductor film previously formed on a film substrate,
In the production of circuit patterns in which metal pattern conductor paths are formed by electrolytic plating, the film thickness of the thin film conductor is 0.1 to 10 μm (1 to 10 μm in the case of electroless plating thin film conductor film), and the electrolytic plating is performed using pyrroline. Using acid copper plating solution, the current density of the cathode is 5~
This is a method for producing a thick film fine pattern having a conductor with a line density of 5 lines/mm or more and a thickness of 20 μm or more, which is the condition of 15 A/dm ² . Line density 5 with a thickness of 20 μm or more on a thin film pattern
In order to thicken a circuit pattern with a thickness of more than 1/m, it is important to perform electrolytic plating using a copper pyrophosphate plating solution at an electrolytic current density of 5 A/dm ² . Figures 1 and 2 show the cross-sectional growth of an electrolytically plated layer (thick layer) when electrolytically plated using a copper pyrophosphate plating solution at cathode current densities of 2 A/dm ² and 5 A/dm ^2. After forming a thin conductive film with a thickness of 0.3 μm using the sputtering method,
Width 85μm, spacing formed by etching method
An example is shown in which a thick layer is grown by electrolytic plating on a thin film conductor pattern of 40 μm (linear density 8 lines/m). In electrolytic plating with a cathode current density of 2A/ ^dm2 ,
The electroplated layer grows at about twice the speed in the width direction as in the thickness direction, and when it grows by 20 μm in the thickness direction, it collides with the adjacent plating layer due to the thickening in the width direction (first ), whereas the cathode current density is
In the case of electrolytic plating at 5 A/dm ² , on the contrary, the plating layer grows at a rate nearly twice as fast in the thickness direction as in the width direction (Figure 2). Figure 3 plots the length in the growth thickness direction against the growth length in the width direction (length in the width direction of the line) of the electroplated layer obtained by the method explained in Figures 1 and 2. The growth curve of the electrolytically plated layer obtained using the copper pyrophosphate plating solution shows an anisotropic plating layer in which the growth rate of the plating layer in the thickness direction is significantly higher than the growth rate of the plating layer in the width direction. It is shown that growth occurs at cathodic current densities of 5 A/dm ² or higher. Cathode current density using copper pyrophosphate plating solution
Electrolytic plating at 5A/dm2 or ^more is an essential condition for producing thick film fine patterns with conductors of 20μm or more in thickness and with a line density of 5 lines/mm or more without causing line-to-line short circuits. be. Particularly suitable cathode current density conditions are 5A/dm ² to 15A/dm ²
It is. In the case of 20 A/dm ² or more, the increase in the film thickness with respect to the increase in the film width becomes larger, which causes burns. The thick film fine pattern with high linear density, which is the object of the present invention, cannot be obtained by electroless plating. In the electroless plating method, even if the film is thickened, the film thickens in the width direction more than the film grows in the thickness direction, resulting in a short circuit. In the present invention, the thickening pattern may be formed on only one side of the film substrate, or may be formed on both sides as necessary. When forming on both sides, it is necessary to drill holes in the film substrate and make through-hole connections. When forming a plurality of patterns on one film substrate, it is preferable to form the patterns on both sides of the film substrate and connect them through through holes, since this makes connection easier. As the semiconductor substrate used in the present invention, all film-like materials such as polyester film, epoxy film, polyimide film, polyparabanic acid film, and triazine film can be used. Acid film and triazine film are preferred. The film thickness of the film substrate is preferably as thin as possible in the sense of high density, but if it is too thin, workability deteriorates, so the film thickness is preferably in the range of 5 to 50 μm, particularly 10 to 25 μm. Further, if necessary, an adhesive layer may be provided on the film substrate in order to improve the adhesion between the film substrate and the conductor. Adhesives include polyester-isocyanate, phenolic resin-butyral, phenolic resin-nitrile rubber, epoxy-nylon, and epoxy-nitrile rubber, which have excellent heat resistance, moisture resistance, and adhesive properties. Epoxy-nitrile rubber adhesives are preferred, particularly epoxy-nitrile rubber adhesives. The thickness of the adhesive is preferably 1 to 20 μm, particularly 2 to 10 μm, from the viewpoint of high density and adhesive properties. The thin film conductor used in the present invention may be any conductive material, but silver, gold, copper, nickel, tin, etc. are preferred, and copper is particularly preferred from the viewpoint of conductivity and economy. In the present invention, the film thickness is 0.1 to 10 μm on the film substrate in advance.
Methods for forming thin conductor films include vapor deposition,
Methods include sputtering, ion plating, electroless plating, and pasting a copper thin film. The present invention does not directly form a thin film conductor in a pattern, but first forms a thin film on the entire surface of the substrate, so if the film thickness is 0.1 μm or more (1 μm or more in the case of electroless plating), it will be uniform and continuous. A membrane is obtained. This thin film conductor film is patterned into a fine pattern before electrolytic plating using a conventionally known photo-etching method, or by masking the thin film conductor film in a pattern with a photoresist. After forming the ink pattern, electrolytic plating is performed. In the latter case, the thin conductive film other than the fine pattern is removed by etching or the like. If the film thickness of the thin film conductor film is 0.1 μm or less, it is difficult to perform uniform electrolytic plating, and if it is 10 μm or more, it is difficult to produce a fine pattern. The preferable range is 0.2 to 5 μm, which makes it difficult to remove thin film conductors remaining outside the electrolytically plated layer pattern by forming a linear density pattern or electrolytically plating. Examples of copper electrolytic plating include cyanide copper plating,
There are copper pyrophosphate plating, copper sulfate plating, copper borofluoride plating, etc., but the present invention particularly uses copper pyrophosphate plating which can be plated in a neutral region.
Copper pyrophosphate plating solution is less likely to damage thin film conductors on film substrates than copper sulfate plating solution. When electrolytically plating fine patterns, an important factor is the current density of the cathode. If the cathode current density is small, the film will become thicker in the width direction than in the thickness direction, and the plating film thickness will become non-uniform. The cathode current density is preferably 5 A/dm ² or more, particularly 5 to 15 A/dm ² . When the depolarizing current density is 5 A/dm ² or less, thickening occurs in the width direction, and when the cathode current density is 20 A/dm ² or more, burning occurs. The electrolytic plating film thickness varies depending on the design value, but is preferably in the range of 10 to 50 μm. Further, in order to further improve reliability, heat treatment after electrolytic plating or treatment such as providing a protective layer made of gold, tin, solder, or polymer is performed as necessary. With the invention described above, thick film fine pattern circuits, for example, 10 to 20 lines/mm, film thickness 20 to
It is possible to provide circuits of 50 μm, and most surprisingly, 35 μm or more, which was previously considered impossible. 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 A thin film conductor pattern with a thickness of 5 μm was formed on a polyimide film “Kapton” (film thickness: 25 μm) manufactured by DuPont by surface treatment, electroless copper plating (film thickness: 5 μm), and photo etching, and then, Using a copper pyrophosphate plating solution manufactured by Hershiyo Murata Co., Ltd., copper was electrolytically plated to a thickness of 20 μm at a cathode current density of 14 A/dm ² to obtain a fine pattern of 12.5 lines/mm with a film thickness of 25 μm. Example 2 Epoxy-nitrile rubber adhesive "XA-564-9" manufactured by Bostik Co., Ltd. was applied to both sides of polyparabanic acid film "Tradron" (film thickness 25 μm) manufactured by Etsuo Chemical Co., Ltd.
After drying, one side was coated with a film thickness of 5 μm, holes were made, and copper vapor deposition was performed to obtain a thin film conductor with a film thickness of 0.3 μm. The area other than the pattern was masked with photoresist (film thickness of 5 μm). Using a copper pyrophosphate plating solution, electrolytically plate copper to a thickness of 35 μm at a cathode current density of 7 A/dm ² , and then remove the thin copper film other than the pattern by etching to a film thickness of 35 μm.
A fine pattern of 10 lines/mm was obtained. Example 3 Example 2 except that the copper is electrolytically plated to a thickness of 50 μm.
A fine pattern of 7.4 lines/mm with a film thickness of 50 μm was obtained by processing in the same manner as above. Comparative Examples 1-2 Except that the cathode current density was as shown in Table 1,
It was treated in the same manner as in Example 1. The results are shown in Table 1.

[Table] Comparative Examples 3 to 4 Comparative Example 3 is the same as Example 2, and Comparative Example 4 is the same as Example 1, except that the film thickness of the thin film conductor is as shown in Table 2.
processed in the same way. The results are shown in Table 2.

[Table] Comparative Example 5 The same process as in Example 2 was carried out except that a copper borofluoride plating solution was used as the electrolytic plating solution. the result,
A short circuit has occurred.

[Brief explanation of drawings]

Figure 1 shows the growth of the electrolytically plated layer when electrolytically plated at a cathode current density of 2A/ ^dm2 , and Figure 2 shows the growth of the electrolytically plated layer when electrolytically plated at a cathode current density of 5A/ ^dm2 . FIG. 3 is a growth curve of a plating layer formed by electrolytic plating using a copper pyrophosphate plating solution. In the figure, 1 is a substrate, 2 is a thin metal plate, and 3 is an electroplated layer.

Claims (1)

[Claims] 1. In manufacturing a circuit pattern in which a metal pattern conductor path is formed by electrolytic plating on a thin film conductor pattern formed by applying a mask method or an etching method to a thin film conductor film previously formed on a film substrate, a thin film conductor is used. The film thickness of the film is 0.1 to 10 μm (1 to 10 μm in the case of electroless plating thin film conductor film)
The line density is 5 lines/mm or ^more and the thickness is
A method for manufacturing thick film fine patterns with conductors of 20 μm or more.