JPH02876B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for manufacturing fine thick film conductive patterns with high density and high reliability.
Fine thick-film conductive patterns are required in fields such as small coils, high-density connectors, and high-density wiring that require high current values. A wire winding method is normally used to manufacture the coil, but this method makes it difficult to manufacture small coils and causes variations in the state of the winding. Also 35μm
So-called printed coils, which are made by etching copper foil, cannot obtain fine patterns because of side etching, and only a pattern of 2 to 3 wires/mm can be obtained at most, making it difficult to manufacture small coils using this method. However, as motors have become smaller in recent years, there has been a demand for the development of fine coils having a fine pattern of 5 lines/mm or more.

The present inventors first formed a resist on a portion other than the pattern portion on a thin metal plate, formed a conductor by electrolytic plating on the pattern portion using the metal thin plate as a cathode, and then used the obtained conductor as an insulator. We proposed a method to obtain a thick film fine pattern conductor by attaching a thin metal plate to a substrate with the thin metal plate facing up and then removing the thin metal plate by etching.

However, since the entire surface of the thin metal plate is etched, the thin metal plate cannot be used as a conductor, and the etching liquid is highly fatigued, resulting in a large consumption of etching liquid.

The present invention relates to an improved method for manufacturing fine thick film conductor patterns for economically producing thick film conductor patterns.

That is, in the present invention, a resist is formed on one surface (a) of a thin metal plate of zinc, aluminum, or tin having a thickness of more than 10 μm and less than 200 μm, except for the conductor pattern portion, and a resist is formed on the other surface (b). A resist is formed on the conductor pattern part, and a conductor is formed on the conductor pattern part on the (a) side by electrolytic plating using a copper pyrophosphate plating solution at a cathode current density of 5 A/dm ² or more, using the metal thin plate as a cathode, and then (b) To provide a method for producing a fine thick film conductor pattern with a linear density of 5 lines/mm or more and a thickness of 20 μm or more, which is characterized by etching and removing a metal thin plate in the form of a conductive pattern from the surface side.

Here, the surface (a) and surface (b) differ only in the shape of the resist pattern to be formed, and the thin metal plate itself does not have different surfaces. Note that the pattern refers to a shape or pattern that forms a part through which electricity is conducted, such as a conductor or a resistor, and is a part that is usually called a circuit.

Since the method of the present invention etches and removes only unnecessary parts of the thin metal plate, the thin metal plate in the conductor pattern portion acts as a conductor, increasing the actual thickness of the conductor pattern, and consuming less etching solution.
This can also contribute to resource conservation. In addition, the method of the present invention etches a thin metal plate into a pattern without removing the resist, which not only simplifies the process but also excels in maintaining the conductor shape and is easy to handle. . As is clear from the above points, the manufacturing method of the present invention is industrially superior.

The thin metal plate used in the present invention may be any material as long as it is a conductor and can be etched, but it is preferably one that has etching characteristics different from electroplated conductors; in this case, the thin metal plate can be etched. During removal, the electrolytically plated conductor is not etched, allowing highly accurate etching of the metal thin plate. Suitable materials include aluminum, tin, and zinc. Moreover, the preferable range of film thickness is 10 to 200 μm. If the film thickness is 10 μm or less, it is difficult to handle and the plating film thickness tends to be uneven. In addition, for film thicknesses of 200 μm or more,
Etching removal takes time and productivity decreases.

As a method for forming a resist on a portion other than the pattern portion used in the present invention, screen printing or gravure printing may be used, but it is preferable to use a photoresist that can easily form a fine pattern. As for the formation method,
It can be obtained through coating, exposure, and development processes. Photoresists include Eastman Kodak's KPR, KOR, KPL, KTFR, KMER,
Tokyo Ohkasha's TPR, OMR81, Fuji Pharmaceutical Co., Ltd.
There are negative types such as FSR, and positive types such as KADR from Eastman Kodak Co. and AZ-1350 from Shipley, but those with excellent plating resistance are preferred, and negative types are particularly preferably used. A dry film resist can also be used.
The thicker the film thickness, the more useful it is in preventing the plating from becoming thicker, but if it is too thick, it will become impossible to obtain a fine pattern, so 0.1 to 50 μm, particularly 1 to 10 μm, is preferable. If the thickness is 0.1 μm or less, pinholes are likely to occur.

The resist patterns formed on the front and back sides are
It is necessary to form patterns with the front and back sides reversed, and it is necessary to match the positional relationship of each pattern.

In the present invention, the electrolytic plating method requires a cathode current density of 5 A/mm in order to form a thick pattern with a thickness of 20 μm or more and a linear density of 5 lines/mm or more.
Electrolytic plating is required at dm ² or higher. The upper limit of cathode current density is determined by burnout.

Figures 1 and 2 are diagrams showing the cross-sectional growth of an electrolytically plated layer when electrolytically plated using a copper pyrophosphate plating solution at cathode current densities of 2 A/dm ² and 5 A/dm ² . Form a resist with a thickness of 5 μm,
Resist width 40μm, spacing 85μm (line density 8 lines/mm)
This is an example in which a conductive layer is formed on a resist pattern by electrolytic plating.

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 to 25 μm in the thickness direction, it collides with the adjacent plating layer and short-circuits (Fig. 1). In electrolytic plating at a current density of 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 shows the growth of the electroplated layer obtained by plotting the length in the growth thickness direction against the growth length in the width direction of the electroplated layer obtained by the method explained in Figures 1 and 2. The curve shows that in electrolytic plating using a copper pyrophosphate plating solution, the plating layer grows in an anisotropic direction in which the plating layer growth rate in the thickness direction is significantly higher than the plating layer growth rate in the width direction at a cathode current density of 5A/
This shows that it occurs at dm ² or higher.

Another important factor in electrolytic plating is the plating film thickness/pattern spacing ratio.
By setting this ratio to 1.4 or more, particularly 2.0 or more at the above cathode current density, thickening in the width direction is further reduced and the film can be selectively plated in the thickness direction.

These phenomena described above are remarkable when adjacent patterns are at equal potential, and the present invention maximizes these effects.

Although there is no particular restriction on the thickness of the electrolytic plating film, the present invention is particularly effective when the electrolytic plating film thickness is thick.
The preferred range is 200 μm, particularly 20 to 200 μm, and more preferably 35 to 200 μm.

Although the method of the present invention can be used where the wiring density is low, it is industrially suitable for wiring densities of 3 lines/mm or more, particularly 5 lines/mm or more. Furthermore, the present invention is particularly suitable for cases where the conductive pattern has a space factor of 50% or more.
It is suitable if it is 70% or more.

In the present invention, the thin metal plate is removed by etching by spraying or dipping using a solution that dissolves the used thin metal plate. Furthermore, when aluminum, tin, or zinc is used as the thin metal plate, it is preferable not to etch the electrolytically plated conductor, for example, by etching with an alkaline aqueous solution, but it is also possible to etch with an acidic aqueous solution such as dilute hydrochloric acid.

After etching, insulation and reliability are improved.
In order to improve mechanical strength, a protective layer may be provided by impregnation, molding, coating, etc. As a protective layer, heat resistance, moisture resistance, insulation,
A material with excellent adhesive properties is preferred, such as an insulating varnish used for coils, etc. Specifically, polyimide, polyamideimide, polyester,
Preferred are polymers such as polyurethane and epoxy resin, and polyester-isocyanate, phenol resin-butyral, phenol resin-nitrile rubber, epoxy-nylon, and epoxy-nitrile rubber polymers. It is also possible to attach the etched fine thick film conductive pattern to an insulating substrate. In this case, as the insulating substrate, a film substrate, a laminated substrate, a glass substrate, a ceramic substrate, a thin metal plate coated with an insulating layer, etc. can be used, and a film-like substrate is particularly preferred. All film-like substrates can be used, such as polyester film, epoxy film, polyimide film, polyparabanic acid film, and triazine film, but polyimide film, polyparabanic acid film, and triazine film are preferred in terms of flexibility and heat resistance. Film is preferred. It is also possible to perform etching after providing a protective layer on the plated surface or pasting an insulating substrate.

It is also possible to stack a plurality of fine thick-film conductive patterns subjected to the above-mentioned treatment, and in this case, electrical connection can be made between the upper and lower conductive patterns by drilling and through-hole connection.

The fine thick film conductive pattern obtained by the present invention is industrially particularly suitable for use in small coils with low resistance, high-density connectors, high-density wiring, and the like.

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 can be modified in various ways.

Example 1 On a thin aluminum plate with a film thickness of 40 μm, after drying a negative resist “Microresist 747-110cst” manufactured by Eastman Kodak Co., it was applied to both the front and back surfaces to a film thickness of 5 μm, prebaked, and a circuit pattern was formed. It is exposed through a mask with a high-pressure mercury lamp, developed using a special developer and rinse solution, and post-baked.
In addition, a resist was formed on the other side in the circuit portion.

Next, using a copper pyrophosphate plating solution manufactured by Hersho Murata Co., Ltd., and using the aluminum thin plate as a cathode, a 100 μm thick copper layer was electrolytically plated on the circuit pattern portion of the surface on which the resist was formed in areas other than the circuit portion. Next, the aluminum thin plate was removed by etching with a solution prepared by diluting 36% by weight hydrochloric acid with water at a ratio of 2:3, and an epoxy surface coating material (ME-264 main agent and HV-106 hardening agent manufactured by Nippon Pernox Co., Ltd. in a weight ratio) was removed.
The surface was overcoated with a 100:27 mixture. As a result, the wiring density was 10 lines/mm, and the film thickness was 140 μm.
(including an aluminum layer of 40 μm), and a fine thick film conductive pattern with a pattern interval of 15 μm was obtained.

Example 2 A negative photoresist “Microresist” manufactured by Eastman Kodak Co., Ltd. was applied on a thin tin plate with a film thickness of 20 μm.
747-110cst" was dried, coated on both the front and back sides to a film thickness of 3 μm on one side, prebaked, and exposed on both sides with a high-pressure mercury lamp through a circuit pattern mask.
It was developed using a special developing solution and a rinsing solution, and post-baked to form a resist on the parts other than the circuit part on one side and on the circuit part on the other side.

Next, using a copper pyrophosphate plating solution manufactured by Hershiyo Murata Co., Ltd. and using a thin tin plate as a cathode, a 50 μm thick copper layer was electrolytically plated on the circuit pattern portion of the surface on which the resist was formed on the portion other than the circuit portion. Next, the thin tin plate was removed by etching with a solution prepared by diluting 36 wt. The surface was overcoated with a mixture of: As a result, the wiring density was 15 lines/mm, and the film thickness was 70 μm (including a tin layer of 20 μm).
), a fine thick film conductive pattern with a pattern interval of 10 μm was obtained.

Example 3 A negative photoresist “Microresist” manufactured by Eastman Kodak Co., Ltd.
747-110cst" was dried, coated on both the front and back surfaces to a film thickness of 3 μm, prebaked, and exposed on both sides with a high-pressure mercury lamp through a circuit pattern mask.
A special developing solution and a rinsing solution were used to develop the resist, and post-baking was performed to form a resist on a portion other than the circuit portion on one side and on the circuit portion on the other side.

Next, using a copper pyrophosphate plating solution manufactured by Hersho Murata Co., Ltd. and using the zinc thin plate as a cathode, a 150 μm thick copper layer was electrolytically plated on the circuit pattern portion of the surface on which the resist was formed on the portion other than the circuit portion. Next, the thin zinc plate was removed by etching with a solution diluted 2:3 with 36% by weight hydrochloric acid, and an epoxy surface coating material (ME-264 main agent manufactured by Nippon Pernox Co., Ltd. and HV
The surface was overcoated with a mixture of -106 curing agent in a weight ratio of 100:27. As a result, wiring density 6
A fine thick film conductive pattern was obtained with a conductor film thickness of 200 μm (including a 50 μm zinc layer) and a pattern interval of 30 μm.

[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, which is a diagram showing the growth status of the electrolytically plated layer, is a growth curve of the electrolytically plated thickness by electrolytically plating using a copper pyrophosphate plating solution. In the figure, 1 is a metal thin plate, 2 is a resist, and 3 is a conductor layer.

Claims (1)

[Claims] 1. On one side (a) of a thin metal plate of zinc, aluminum or tin with a thickness of more than 10 μm and less than 200 μm, a resist is formed on the part other than the conductor pattern, and on the other side (b), a resist is formed on the conductor pattern. The metal thin plate is used as a cathode, and a copper pyrophosphate plating solution is used on the conductor pattern on the (a) side to increase the cathode current density.
Line density 5, which is characterized by forming a conductor by electrolytic plating at 5A/dm ² or more, and then etching and removing the thin metal plate from the (b) side in the form of a conductor pattern.
A method for manufacturing fine thick film conductor patterns with a thickness of 20 μm or more and a thickness of 20 μm or more.