JPS61254039A - Forming method for circuit pattern - Google Patents

Abstract

PURPOSE:To enable fine circuit patterns to be formed, by flattening the surface of the patterns, and plating them electrolytically, after the circuit patterns are formed by means of etching. CONSTITUTION:Firstly, on the both surfaces of an insulating layer 1, substrates with formed copper foil layers 2A, 2B are arranged. Secondly, after a slot 3 for a through hole is bored and the layers are patterned with photoresists 4A, 4B, the layers are treated by means of etching to remove unnecessary sections and to form coil patterns 5A, 5B. Third, after the photoresists 4A, 4B are exfoliated, spaces between formed coil patterns 5A, 5A and coil patterns 5B, 5B are filled up with insulating resin 6A, 6B and the pettern surfaces are polished and flattened. Finally, the patterns are electrolytically plated, and copper is separated out on the coil patterns 5A, 5B, and coil patterns 7A, 7B are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention relates to a circuit pattern forming method used when forming a circuit pattern on an insulating layer, and is suitable for manufacturing printed coils for small motors, for example. It is something.

B0 Summary of the Invention The present invention is a circuit pattern forming method used when forming a circuit pattern on an insulating layer, in which a circuit pattern is formed by etching, and then the surface is flattened and electroplated. According to the present invention, a circuit pattern can be formed, the thickness of the pattern can be increased without causing any inconvenience, and the space factor can be increased.

C0 Prior Art Conventionally, motors have been widely used in devices that require a power source. For example, as shown in FIG. 5, the coils of this motor are made by winding a so-called enamelled wire having an enamel layer 12 around a copper wire 11 into a core (not shown).
It is manufactured by wrapping the

On the other hand, in recent years, with the spread of portable cassette tape players, cassette tape recorders (so-called headphone stereos), etc., there has been a demand for the development of smaller motors with better performance. However, it is difficult to manufacture coils for such small motors using the above-mentioned winding method. This is because the winding machine is expensive, it is not possible to manufacture multiple coils at the same time, it is difficult to thin the wire to 100 μm or less (because the diameter of the copper wire 11 must be at least 100 μm), and the interconnection of each winding is required. This is because it has drawbacks such as difficulty in soldering work.

In contrast, a method has been proposed in which coils (so-called printed coils/L/) are formed on both sides of an insulating substrate by etching or plating. As shown in FIG. 6, the etching method is a method in which coil patterns 14A and 14B are formed by etching both sides of an insulating substrate 13 made of polyimide or the like on which a copper foil layer is formed. , for example, as shown in FIG.
After patterning the odd resists 17A and 17B,
Coil pattern 18A by depositing copper by electrolytic plating,
This is a method of forming 18B.

D1 Problems to be Solved by the Invention According to such an etching method or a plating method, a winding machine is not required and a plurality of coils can be manufactured at the same time. However, each method has the following drawbacks.

(a) In the case of the etching method, in order to obtain the thickness TE of the patterns 14A and 14B, the original copper foil layer needs to be thick, so it is difficult to obtain the desired shape, and as shown in the figure, the pattern becomes thin due to the side etching phenomenon. I end up. Also, the gap between patterns (h is 1
The limit is approximately 00 μm, and it cannot be made smaller than this, making it impossible to form a fine pattern. Furthermore, due to these factors, the space factor (conductor occupancy factor), which greatly affects the performance of the motor, becomes low. Furthermore, electrical connections must be made between the patterns (conductors) on both sides via the insulating substrate 13.

! (b) In the case of the plating method, electrode metal foil layers 15A and 15B are required for plating, and must be removed after plating.

Furthermore, at this time, it is necessary to peel off the photoresists 17A and 17B, but this is structurally difficult. Furthermore, pattern 18
In order to increase the thickness TM of A and 18B, it is sufficient to increase the thickness TMP of photoresists 17A and 17B, but there is a risk that the resolution of photoresists 17A and 17B may decrease or they may contact (short circuit) with adjacent patterns. There is, thickness TM
cannot be made too thick, and the space factor will decrease. Furthermore, the width WM of the pattern is limited to about 100 pm due to the requirement of the thickness TM, making it impossible to form a fine pattern.

Therefore, the present invention has been proposed in view of the above-mentioned conventional problems, and provides a circuit pattern that can be made finer, thicker without causing any inconvenience, and that can increase the space factor. The purpose is to provide a forming method.

Means for Solving the E0 Problem In order to achieve the above-mentioned object, the circuit pattern forming method according to the present invention etches the conductive layer on a substrate on which the conductive layer is formed on the insulating layer. It consists of a step of forming a conductive circuit pattern, a step of burying an insulating resin into the gap between the formed circuit patterns and flattening it, and a step of applying electrolytic plating on the formed circuit pattern. It is characterized by Koki.

21 Effects According to the present invention, after circuit patterns are formed by etching, the gaps between the circuit patterns are filled with an insulating resin to flatten the surface, and the thickness of the pattern is increased by electrolytic plating.

G. Example Hereinafter, an example of the circuit pattern forming method according to the present invention will be described in detail with reference to the drawings. In this embodiment, the present invention is applied to a method of forming a coil (printed coil) pattern for a small motor.

First, as shown in FIG.
A substrate on which A and 2B are formed is prepared.

For example, materials such as polyimide, polyamide, polyester, diallyl phthalate, polybutadiene, and epoxyurethane can be used for the insulating layer 1, and the thickness Tor is about 5 to 15 μm. In addition, the copper foil layer 2
A and 2B are formed by electrolytic plating, rolling, etc., and the thickness Toc is about 8 to 85 μm.

Next, as shown in FIG. 2, a hole 3 serving as a through hole is made and photoresists 4A and 4B are patterned, and then an etching process is performed to remove unnecessary portions to form coil patterns 5A and 5B. The hole 3 is, for example,
It may be formed to a diameter of about 0.5 to 1.5 mm using a drill. Further, liquid renost or dry film resist may be used as the photoresists 4A and 4B, and a thickness TOP of about 1 to 10 μm is sufficient.

Further, the above etching treatment is carried out using, for example, an etching solution such as ferric chloride or cupric chloride at a rate of 2 kg/C.
- It is sufficient to use a spray method under conditions of about -.

Next, after peeling off the photoresists 1-4A and 4B, the third
As shown in the figure, the formed coil patterns 5A, 5A
The gaps between the coil patterns 5B and 5B are filled with an insulating resin such as epoxy resins 5A and 15B, and the surfaces are polished to make them flat. This resin 6
By filling A and 6B, it is possible to prevent abnormal growth of copper in the horizontal direction and contact (short circuit) with adjacent patterns in the next plating process.

Finally, electrolytic plating is performed using a plating bath such as copper sulfate or copper pyrophosphate to deposit copper on the coil patterns 5A and 5B, resulting in a new coil pattern 7A as shown in FIG.

Get 7B. At this time, electrical connections between the coil patterns on both sides can be made at the same time, and through holes 8 are formed. Note that the gap Go between patterns is extremely small (preferably 80 to 40
The plating precipitation is stopped when the thickness reaches 100 μm.

As described above, the method for forming the coil pattern of this embodiment uses etching and electrolytic plating in combination, and a good coil pattern can be obtained through a simple manufacturing process. That is, even if the thickness Toc of the original copper foil layers 2A, 2B and the thickness Top of the photoresists 4A, 4B are thin, thick coil patterns 7A, 7B with a thickness TO can be obtained, the pattern can be reinforced, and the pattern can be reinforced. A pattern with a shape can be easily formed. In addition, resins 6A and 6B
This filling prevents the copper deposited by electrolytic plating from coming into contact with adjacent patterns, making it possible to set the gap Go between the patterns to a minimum. Furthermore, because of this, the pattern can be made finer and the space factor can be increased.

Here, the space factor of each coil formed by the above-mentioned etching method (see Figure 6), plating method (see Figure 7), and this example (see Figure 4) is expressed as the cross-sectional area ratio of the conductor. An example of comparison is shown below. The conditions are as follows. The unit is μ door.

(a) Etching method WE=lOOGE=100 TE=100(bl
Plating method WM = 100 0M = 80 TM =
60 (TMP=25) (C) This example Wo=50 Go=80 To=100(T
oc = 40) As a result of calculating each cross-sectional area SE, SM, and So under the above conditions, the cross-sectional area ratio is 8g: SM: So = l: 1.15:
1.26, which shows that the space factor of the coil formed in this example is extremely high. Therefore, a high-performance compact motor can be obtained.

Note that the present invention can be applied not only to printed coils but also to methods for forming circuit patterns on ordinary printed circuit boards. Further, it goes without saying that the circuit pattern to be formed may be formed on one side.

H0 Effects of the Invention As is clear from the description of the embodiments described above, according to the present invention, after forming a circuit pattern by etching, the surface is flattened and electrolytically plated to form a fine circuit pattern. The thickness of the pattern can be increased without causing any inconvenience, and the space factor can be increased.

[Brief explanation of drawings]

FIGS. 1 to 4 are cross-sectional views showing an embodiment of the present invention in the order of steps. Figures 5 to 7 are cross-sectional views showing coils formed by conventional methods, with Figure 5 showing the winding method, Figure 6 the etching method, and Figure 7 the plating method. It is. 1・・・・・・・・・・・・・・・Insulating layer 2A,
2B...Copper foil layer 5A, 5B, 7A, 7B...Quill pattern 6A
, 6B...Resin

Claims (1)

[Claims] In a substrate having a conductive layer formed on an insulating layer, a step of etching the conductive layer to form a circuit pattern that is integrally conductive; and a step of etching the conductive layer to form an integrally conductive circuit pattern; A circuit pattern forming method comprising the steps of embedding and flattening a resin, and performing electrolytic plating on the formed circuit pattern.