JPH02874B2 - - 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. The winding method is normally used to manufacture coils, but
With this method, it is difficult to manufacture small coils, and the state of the windings varies. In addition, so-called printed coils made by etching 35 μm copper foil do not produce fine patterns because of side etching, and only a pattern of 2 to 3 wires/mm can be obtained at most, and this method also makes it difficult to manufacture small coils. It's difficult. 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 part other than the pattern part on a thin metal plate, formed a conductor by electrolytic plating on the pattern part 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. At the same time, we also proposed a method of re-plating after the above treatment in order to obtain an even thicker conductor pattern. However, the method of re-plating increases the number of plating steps, and if the resist pattern is disturbed between the etching step after the first plating step and the second plating step, shorts may occur between the conductor patterns. Great care was required in handling.

The present invention relates to a method for manufacturing a fine thick film conductive pattern for easily obtaining a thick conductive pattern, which solves the above-mentioned problems.

That is, in the present invention, a resist is formed on both the front and back surfaces of a thin metal plate of zinc, aluminum, or tin having a thickness of more than 10 μm and less than 200 μm in areas other than the pattern area, and a copper pyrophosphate plating solution is applied to the pattern area using the thin metal plate as a cathode. Electrolytic plating is performed at a cathode current density of 5 A/dm ² or more using a metal plate to form a conductor on both the front and back sides.Then, the resist on the thin metal plate is peeled off, and the portion of the thin metal plate covered with resist is removed by etching. The present invention provides a method for manufacturing a fine thick film conductive pattern having a linear density of 5 lines/mm or more and a thickness of 30 μm or more, including the steps of:

Note that a pattern refers to a shape or pattern that forms a part that conducts electricity, such as a conductor or a resistor.
This is the part called the normal circuit.

According to the method of the present invention, a thick conductive pattern can be formed in one plating process, and since there is no second plating process, there is no problem of disturbance of the resist pattern that occurs during handling between processes, and unnecessary parts of the thin metal plate are eliminated. Since only the etching is removed by etching, the thin metal plate in the pattern portion acts as a conductor and helps reduce the resistance value, which also contributes to shortening the processing time of the etching process and saving resources.

From the above, the manufacturing method of the present invention is industrially superior.

The thin metal plate used in the present invention may be anything that is a conductor and can be etched, but it is preferable to use a thin metal plate that has etching characteristics different from those of an electrolytically plated conductor. The electrolytically plated conductor is not etched when removed by etching, 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. 10μm
If the film thickness is below, it is difficult to handle and the plating film thickness tends to be uneven. In addition, for film thicknesses of 200μm or more,
It takes time to remove etching, which reduces productivity.
In addition, sand etching causes peeling between the front and back plating layers.

In the present invention, resist may be formed in areas other than the pattern area by screen printing or gravure printing, 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 Eastman Kodak's KADR and Shipley's AZ-1350, 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, 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
The front and back sides may be the same or different, but it is necessary to match the positional relationship of each pattern.

In the present invention, in order to form a pattern on a thin film pattern with a thickness of 30 μm or more and a linear density of 5 lines/mm or more, the electrolytic plating method is as follows:
Using copper pyrophosphate plating solution, cathode current density
It is necessary to electrolytically plate at 5A/dm2 or ^higher . The upper limit of the cathode current density is determined by the burn.

Figures 1 and 2 show the cross-sectional growth of an electroplated layer when electrolytically plated using a copper pyrophosphate plating solution at cathode current densities of 2 A/dm ² and 5 A/dm ^2. 5μm thick, resist width 40μm, interval 85μm (line density 8 lines/mm)
This is an example in which a conductive layer is grown by electrolytic plating on a resist pattern.

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 (Figure 1). In electrolytic plating at a current density of 5 A/dm ² , on the other hand, 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 this occurs at dm ² or higher.

Another important factor in electrolytic plating is the ratio of plating film thickness/pattern spacing.
By increasing the value to 2.0 or more, the thickening in the width direction is further eliminated 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. The method of the present invention is effective for any conductor film thickness, but is effective when the electrolytic plating film thickness is large, and the preferable range for the electrolytic plating film thickness is 15 to 200 μm on one side of the metal thin plate and 30 to 400 μm for both sides in total. , 40μm on both sides
Furthermore, it is particularly suitable for creating fine patterns having a film thickness of 70 μm or more.

Although the method of the present invention can be used in places with low wiring density, it is industrially suitable for wiring of 3 wires/mm or more, especially 5 wires/mm.
Suitable for wiring density of lines/mm or higher.

Furthermore, the present invention is suitable when the space factor of the conductive pattern is 50% or more, particularly 70% or more.

To remove the resist, use a commercially available remover.
For example, spraying or dipping may be performed using a resist stripper J-100 manufactured by Indust-Ri-Chem-Laboratory. However, it is necessary to choose a stripping solution that does not attack the thin metal plate or plated metal.

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 metal thin plate, it is preferable to not etch the electrolytically plated conductor, for example, to etch it with an alkaline aqueous solution, but it is also possible to etch it 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. The protective layer is preferably one with excellent heat resistance, moisture resistance, insulation, and adhesive properties, such as insulating varnish used for coils, etc. Specifically, polyimide, polyamideimide, polyester, polyurethane, epoxy resin, etc. and polyester-isocyanate-based, phenolic resin-butyral-based, phenolic resin-nitrile rubber-based, epoxy-nylon-based, and epoxy-nitrile rubber-based polymers are preferred. It is also conceivable to attach an etched fine thick film conductive pattern to an insulating substrate. In this case, insulating substrates include film substrates, laminated substrates, glass substrates,
A ceramic substrate, a metal substrate 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. Further, as shown in FIG. 4, it is also possible to provide a protective layer or affix an insulating substrate on one side of the electrolytically plated product, and then remove the resist on the other side and remove the thin metal plate by etching.

It is also possible to laminate a plurality of fine thick-film conductive patterns subjected to the above-mentioned treatment, and in this case, electrical connections 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 various modifications can be made.

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. Both sides are exposed with a high-pressure mercury lamp through a mask,
It was developed using a dedicated developing solution and a rinsing solution, and post-baked to form a resist in areas other than the circuit area.

Next, using a copper pyrophosphate plating solution manufactured by Harshio Murata Co., Ltd. and using a thin aluminum plate as a cathode, copper was electrolytically plated on both sides of the patterned portion to a thickness of 100 μm per side. After removing the resist using Resist Strip J-100 solution manufactured by Industrie Chemie Laboratory, the thin aluminum plate covered with resist was etched away using a solution prepared by diluting 36% by weight hydrochloric acid with water at a ratio of 2:3. , epoxy surface coating material (ME manufactured by Nippon Pernox Co., Ltd.)
-264 main agent and HV-106 curing agent in a weight ratio of 100:27
The surface was overcoated with a mixture of As a result, the wiring density was 10 lines/mm, the film thickness was 240 μm (including the 40 μm aluminum layer), and the pattern spacing was 15 μm.
A fine thick film conductive pattern 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, exposed on both sides with a high-pressure mercury lamp through a circuit pattern mask, and developed using a special developer and rinse solution. , a resist was formed on the parts other than the circuit part by post-baking.

Next, using a copper pyrophosphate plating solution manufactured by Hersho Murata Co., Ltd. and using a thin tin plate as a cathode, copper was electrolytically plated on both sides of the patterned portion to a thickness of 50 μm per side. After removing the resist using Resist Strip J-100 manufactured by Industrie Chemie Laboratory, the thin tin plate covered with resist was etched and removed using a solution prepared by diluting 36% by weight hydrochloric acid with water at a ratio of 2:3. The epoxy surface coating material (ME-264 main agent and HV-106 manufactured by Nippon Pernox Co., Ltd.)
The surface was overcoated with a mixture of curing agents at a weight ratio of 100:27. As a result, the wiring density is 15 lines/
A fine thick film conductive pattern with a thickness of 120 μm (including a 20 μm tin layer) and 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.
It was developed using a dedicated developing solution and a rinsing solution, and post-baked to form a resist in areas other than the circuit area.

Next, using a copper pyrophosphate plating solution manufactured by Hersho Murata Co., Ltd. and using a thin zinc plate as a cathode, copper was electrolytically plated on both sides of the patterned portion to a thickness of 150 μm per side. After removing the resist using Resist Strip J-100 solution manufactured by Industrie Chemie Laboratory, the thin zinc plate covered with the resist was removed by etching with a solution prepared by diluting 36% by weight hydrochloric acid with water at a ratio of 2:3. , 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 with a conductor film thickness of 350 μm (including a zinc layer of 50 μm) and a pattern interval of 30 μm is obtained.

[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 . A diagram showing the growth status of the electrolytically plated layer, FIG. 3 is a growth curve of electrolytically plated thickness by electrolytically plating using a copper pyrophosphate plating solution, and FIG. 4 is an explanatory diagram of one embodiment of resist stripping and etching treatment. . In the figure, 1 is a metal thin plate, 2 is a resist, 3 is a conductive layer, and 4 is a protective layer.

Claims (1)

[Claims] 1. Resist is formed on both the front and back sides of a thin metal plate of zinc, aluminum, or tin with a thickness of more than 10 μm and less than 200 μm in areas other than the pattern area, and a cathode current is applied to the pattern area using a copper pyrophosphate plating solution with the metal thin plate as a cathode. It is characterized by performing electrolytic plating at a density of 5 A/dm ² or more to form conductors on both the front and back sides, then peeling off the resist on the thin metal plate surface, and removing the portion of the thin metal plate covered with resist by etching. Thickness 30μ with linear density of 5 lines/mm or more
A method for manufacturing a fine thick film conductive pattern of m or more.