JPH0199454A - Manufacture of sheet coil - Google Patents

Abstract

PURPOSE:To prevent the short circuit of a metallic deposit pattern to be formed on a coil pattern by setting the pitch and opening width of resist layers at given values at the time of an etching treatment and by keeping the line width of said coil pattern almost constant from the outer periphery to the inner periphery thereof. CONSTITUTION:After a resist has been applied to the whole surface of a conductor thin film 2 laminated on a base 1, the applied surface is exposed to light and developed so that resist layers 3a, 3b are left in coil pattern-forming parts. In this case, the pitches P3, P4 and opening widths W1, W2 of said resist layers 3a, 3b are changed so that the pitch P1 of a coil pattern 4 on the outer peripheral side is larger than the pitch P2 of said coil pattern 4 on the inner peripheral side and the line width of the coil pattern 4 is kept almost constant from the outer periphery to the inner periphery thereof. After that, an etching treatment is applied to said conductor thin film 2 by the use of said resist layers 3a, 3b as masks and then the resist layers 3a, 3b are removed to obtain the coil pattern 4. A metallic deposit pattern 5 is formed on said coil pattern 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a sheet coil having a fine pitch pattern.

[Summary of the invention]

The present invention provides a method for manufacturing a sheet coil in which plating is grown on a coil pattern formed on a substrate. By making it substantially constant from the inner circumference to the inner circumference, short circuits of the plating layer pattern formed on the coil pattern are prevented, and
The present invention provides a method for manufacturing a sheet coil with high reliability that improves the space factor and yield of a coil pattern.

[Conventional technology]

Conventionally, for example, motors and rotary transformers used coils wound with copper wire, but in recent years there has been a strong desire to make these products smaller and thinner, and sheet coils with coil patterns formed by etching have become more popular. Motors and rotary transformers that utilize this have been proposed.

For example, the sheet coil has a fine-pitch coil pattern having predetermined characteristics on a sheet-like substrate. To create this sheet coil, first, a conductive thin film was formed on a sheet-like substrate, and a resist layer was applied to it at equal intervals from the outer circumference to the inner circumference to form the desired spiral shape. Thereafter, by performing an etching process, a fine-pinch coil pattern having predetermined characteristics is formed. Fine-pitch coil patterns formed by etching in this way require the use of thick conductor thin films to improve reliability, but when etching is applied to such coil patterns, There is a risk that side etching may occur, resulting in a coil pattern that lacks reliability. Therefore, the conductor thin film formed on the substrate must be extremely thin, which reduces the cross-sectional area of the coil pattern (hereinafter referred to as space factor) and improves the properties of the sheet coil. is difficult.

Therefore, in order to improve the space factor of the fine-pitch coil pattern as described above, electrolytic plating is applied to the substrate on which the coil pattern is formed to form a plating layer pattern on the coil pattern. It is proposed to improve the

[Problems to be Solved by the Invention] However, in electrolytic plating performed to improve the space factor of a coil pattern, the plating is deposited thickly in areas where the potential difference is high, that is, areas close to the electrodes, and in areas where the potential difference is low, That is, there is a tendency for plating to be thinly deposited in areas that are farther away from the electrode.

When electrolytic plating with this tendency is applied to a coil pattern, since the coil pattern is formed at a fine pitch at approximately equal intervals from the outer circumference to the inner circumference, the plating layer is more likely to be formed on the outer coil pattern. Plating layer patterns that are thickly deposited and formed on adjacent coil patterns may short-circuit to each other, causing a short circuit. This results in a decrease in product reliability and yield.

Therefore, the present invention was proposed in view of the above-mentioned problems, and it is possible to prevent short circuits in the plating layer pattern formed on the coil pattern, and to improve the space factor and yield of the coil pattern. The purpose of the present invention is to provide a highly reliable sheet coil manufacturing method.

[Means for solving problems]

In order to solve the above-mentioned problems and achieve the above-mentioned objects, the present invention etches a conductive thin film laminated on a substrate to form a coil pattern, and then performs electrolytic plating to grow the plating on the coil pattern. In the sheet coil manufacturing method, the pitch and opening width of the resist layer during etching are adjusted so that the pitch P1 on the outer circumference of the coil pattern is greater than the pitch P2 on the inner circumference of the coil pattern, and the line width of the coil pattern is changed from the outer circumference to the inner circumference. It is characterized by being substantially constant over the period of time.

[Effect]

For example, when applying electrolytic plating to a coil pattern that has a very long length, such as a sheet coil, on which a plating layer pattern should be formed, the plating layer pattern should be formed on the outer circumferential side near the electrode, as shown in Figure 6. A thick plating layer pattern is formed on the coil pattern, and then a thin plating layer pattern is gradually formed on the coil pattern as the distance from the electrode increases. The thickness of the plating layer pattern formed on the coil pattern tends to be approximately constant on the inner circumferential side beyond about 115 lengths of the total coil pattern length. Further, the above electrolytic plating has a characteristic that the faster the current density, the more the plating grows upward.

Note that the characteristics shown in Figure 6 are based on the current density of approximately 40 A/dm.
This is when electrolytic plating was performed as t.

Therefore, the pitch of the coil pattern on the outer peripheral side corresponding to the portion where the plating is thickly formed, that is, about 115 of the total coil pattern length, is changed as follows.

That is, when forming a coil pattern, the pitch and opening width of the resist layer applied on the conductive thin film are adjusted so that the pitch P1 on the outer circumferential side of the coil pattern is greater than the pitch P2 on the inner circumferential side of the coil pattern, and the lines of the coil pattern When the conductor thin film is etched so that the width is substantially constant from the outer circumference to the inner circumference, the distance between the formed coil patterns on the outer circumference side becomes larger than the distance between the coil patterns on the inner circumference side.

Therefore, even if the coil pattern is subjected to electrolytic plating and plating is grown, the adjacent coil patterns on the outer circumferential side will not be short-circuited and the plating will be high (plated) in the thickness direction.

〔Example〕

Hereinafter, a method for manufacturing a sheet coil to which the present invention is applied will be described with reference to the drawings.

First, as shown in FIG. 1, a conductive thin film 2 is formed as a coil pattern on a substrate 1 by etching in a later process.
Laminate.

The substrate 1 needs to have excellent insulation properties, and preferably has excellent properties such as flexibility and heat resistance. Examples of such materials include epoxy resins and polyimide resins. The conductive thin film 2 is made of a material having predetermined characteristics as a coil pattern, such as a conductive metal such as copper or aluminum, and
They may be formed by laminating them to a predetermined thickness.

Next, as shown in FIG. 2, a resist is applied over the entire surface of the conductor thin film 2, and then exposed to light so as to obtain a desired spiral coil pattern, and then a resist layer 3a is applied to the coil pattern forming area. , 3b remain.

Here, the resist layer 3a is formed in the development process.

3b, the pitch of the resist layers 3a and 3b is changed, and the pitch of the coil pattern is changed.

However, for example, the resist 1i3a on the outer circumferential side and the inner circumferential side
, 3b is changed and the etching process is performed while keeping the opening widths W+ and Wz between the resist layers 3a and 3b constant, the line width of the formed coil pattern is such that the line width on the outer circumference side becomes the line width on the inner circumference side. In addition to being wider than the width, there is no difference in brightness between patterns from the outer circumferential side to the inner circumferential side. For this reason,
As shown in Fig. 6, the electrolytic plating in the post-process has the characteristic that the plating is deposited thicker on the outer circumference side of the coil pattern, which corresponds to about 115 of the total coil pattern length. The plating on the outer circumference may cause a short circuit.

Therefore, when forming a coil pattern, the entire coil pattern is divided into an outer circumferential side and an inner circumferential side, and the pitch P3 of each resist layer 3a, 3b. P- and opening width W,,W,
By changing the plating layer pattern formed on the coil pattern, short circuits can be prevented. That is, by adjusting the pitches P, , P and opening widths W, , W of the resist layers 3a and 3b during etching processing, a coil pattern on the outer peripheral side corresponding to a length of about 115 mm of the total coil pattern length is obtained. The outer circumferential pitch P of the coil pattern is made larger than the inner circumferential pitch P2 of the inner circumferential coil pattern, and the line width of the coil pattern is formed to be approximately constant from the outer circumference to the inner circumference. This is to prevent short-circuiting between adjacent plating layer patterns that are deposited thicker on the outer circumferential coil pattern during electrolytic plating.

In this example, the pitch P3 of the resist layer 3a for forming the outer coil pattern was 150 μm, and the pitch P4 of the resist layer N3b for forming the inner coil pattern was 135 μm. Furthermore, the opening width Wl between the resist layers 3a on the outer peripheral side (the distance between the openings between the resist layers 3a) is set to 40I1m, and the opening width WZ between the resist layers 3b on the inner peripheral side (the distance between the openings between the resist layers 3b) is set to 40I1m. distance) was set to 30 μm.

Thereafter, as shown in FIG. 3, the conductive thin film 2 is subjected to an etching process using the resist layers 3a and 3b formed in the above steps as masks. Then, when the resist layers 3a and 3b were removed, a spiral coil pattern 4 having a desired shape as shown in FIG. 4 was obtained.

Table 1 below shows the experimental results when the etching process was performed under the conditions described above, with the number of turns of the coil pattern being 16 turns in total.

Note that the numbers 1, 2, 3, . . . , 16 in the table indicate the coil patterns formed sequentially from the inner circumferential side to the outer circumferential side. Also, A, B, and C in the table.

D is the opening between A and the resist layers, B: the distance from the end of the resist layer on the inner peripheral side of each resist layer to the coil pattern, and C: the line width of the coil pattern.

D: Indicates the distance from the end of the resist layer on the outer peripheral side of each resist a to the coil pattern. And the above A,
The units of the values of B, C, and D were μm.

<Margin below> As can be seen from the above results, the line width A of the coil pattern 4 is approximately constant from the outer circumference to the inner circumference, and at the same time, the line width A on the outer circumference side of the coil pattern 4 is approximately constant. It was formed on the circumferential side Pg.

In addition, as can be seen from Table 1, the distance between the coil patterns 4 with 4 turns on the outer circumference, which corresponds to about 115 of the total length of the 4 coil patterns, is greater than the distance between the coil patterns 4 with 12 turns on the inner circumference. Largely formed. That is, the line width A of the coil pattern 4 is formed to be a substantially constant line width, and the outer circumferential pitch P1 of the coil pattern 4 is larger than the inner circumferential pitch P.
2, the distance between the coil patterns 4 with 4 turns on the outer circumferential side>the distance between the coil patterns 4 with 12 turns on the inner circumferential side. Note that the outer pitch P1 and the inner pitch P2 are respectively represented by A+B+C+D. Also,
The distance between the coil patterns 4 is represented by A+B+C. Therefore, specifically, the distance between the coil patterns on the inner circumferential side is 90 to 100 μm, and the distance between the coil patterns on the outer circumferential side is 115 to 120 μm.

The 4° distance between the four turns of the coil pattern on the outer circumferential side is set to be a necessary and sufficient distance so that adjacent plating layer patterns formed in the next step of electrolytic plating do not come into contact with each other. Therefore, during electrolytic plating in the next step, the plating deposited on the outer circumferential coil pattern 4 does not come into contact with the plating deposited on adjacent coil patterns 4. Further, since the coil pattern 4 has a substantially constant line width, it is possible to form a sheet coil having uniform characteristics without variation in the resistance of each coil pattern 4. Note that the coil pattern 4 may be formed only on one side of the substrate 1 as described above, or may be formed on both sides.

Next, as shown in FIG. 5, electrolytic plating is applied to the coil pattern 4 formed as described above, and the plating is grown on the coil pattern 4.

When performing electrolytic plating, the substrate 1 on which the coil pattern 4 was formed was used as a cathode and the copper plate was used as an anode in a plating bath.

The conditions for performing the electrolytic plating are as follows: First, the composition of the plating solution in the plating bath is changed to Cu5O, 5Hz O: 100g/f.
! , H, So,: 200g/l, additive: 5cc/f
I made it fi. Then, set the temperature of the plating liquid to about 40°C.
Keeping the temperature at ~50℃, the current density is 20A/dm”
The above current density is set in the range of 20 A/dm to 40 A/dm for the following reason. If electrolytic plating is performed with the coil pattern 4 set to 5 A/dm or less, the plating tends to grow in the width direction of the coil pattern 4 and does not grow well in the thickness direction.
The space factor of the coil pattern 4 cannot be improved. Furthermore, if electrolytic plating is performed at the above current density of 60 A/dm" or more, copper will precipitate as granular protrusions, making it impossible to form a good plating layer. Therefore, the above current density is 2 OA/dm" or more. dm" to 40 A/dm".

When the substrate 1 is electrolytically plated under the above conditions,
Plating is deposited on the coil pattern 4, and the plating gradually grows in the thickness direction. When electrolytic plating is carried out for a predetermined period of time, a plating layer pattern 5 having a high space factor is formed on the coil pattern 4 as shown in FIG. Here, when observing the plating layer pattern 5 with a microscope, it is observed that in the sheet coil created by the conventional method (constant pitch), the plating deposited on the outer circumference side of the coil pattern 4 is connected to each other in many places. However, in the plating layer pattern 5 on the coil pattern 4 obtained by the method of the present invention, no contact was observed at all from the outer circumference to the inner circumference. That is, in the step, the pitch P on the outer circumferential side of the coil pattern 4,
> Since the inner pitch is P2 and the line width of the coil pattern 4 is approximately constant from the outer circumference to the inner circumference, the distance between the coil patterns 4 in the four-tang part on the outer circumference is sufficient. This is because adjacent plating layer patterns do not come into contact with each other. Even if the plating is deposited thicker on the outer coil pattern 4, the plating layer patterns 5 formed on the adjacent coil patterns 4 will not be short-circuited to cause a short circuit. Therefore, it is possible to prevent short-circuiting of the plating layer pattern 5 formed on the coil pattern 4, and to provide a highly reliable sheet coil in which the space factor and yield of the coil pattern 4 are improved.

〔Effect of the invention〕

According to the method of the present invention, when forming a coil pattern,
Since the outer circumferential pitch P1 of the coil pattern is greater than the inner circumferential pitch P2, and the - line width of the coil pattern is formed to be approximately constant from the outer circumference to the inner circumference, a distance between the coil patterns on the outer circumferential side is required. This is sufficient to prevent short circuits in the plating layer pattern formed on the coil pattern.

Therefore, the yield of coil patterns can be improved and a highly reliable sheet coil can be provided.

[Brief explanation of the drawing]

FIGS. 1 to 5 are enlarged cross-sectional views of main parts showing the sheet coil manufacturing method according to the present invention in the order of steps,
FIG. 1 shows the conductor thin film forming process, FIG. 2 shows the resist layer forming process, FIG. 3 shows the etching process, FIG. 4 shows the coil pattern forming process, and FIG. 5 shows the electrolytic plating process. FIG. 6 is a characteristic diagram showing the relationship between the length of the coil pattern and the thickness of the plating layer pattern. 1...Substrate 2...Conductor thin films 3a, 3b...Resist layer 4...Coil pattern 5...Plating layer pattern Patent Applicant: Sony Corporation Agent
Patent Attorney Koike Mima Ei Tamura - Same Masaru Sato Figure 1 Figure 2 Figure 3 Koinoshi Ha 0 Dah〉2%Energy〱To Department/Child Process Figure 5 Coil lever 1 tool〉Length 1 1- Figure 6

Claims (1)

[Claims] A sheet coil manufacturing method in which a conductive thin film laminated on a substrate is etched to form a coil pattern, and then electrolytic plating is applied to grow the coil pattern, comprising: By adjusting the pitch of the resist layer and the opening width, the outer circumferential pitch of the coil pattern P_1>
A method for manufacturing a sheet coil, characterized in that the inner pitch is P_2 and the line width of the coil pattern is substantially constant from the outer circumference to the inner circumference.