JP7534614B2 - Manufacturing method of coil substrate and manufacturing method of coil substrate for motor - Google Patents

Description

The present invention relates to a method for manufacturing a coil substrate and a method for manufacturing a coil substrate for a motor.

Patent Document 1 discloses a coil component. The coil component is formed of an element body having a first surface and a second surface opposite the first surface, a first conductor pattern on the first surface, a second conductor pattern on the second surface, and a metal pin that connects the first conductor pattern and the second conductor pattern.

WO2017/134993 publication

[Problems with patent documents]
In the technique disclosed in Patent Document 1, the first conductor pattern and the second conductor pattern are connected by a metal pin, which makes it difficult to reduce the thickness of the coil component.

The method for manufacturing a coil substrate according to the present invention includes preparing a flexible substrate including a flexible material having a first surface and a second surface opposite to the first surface, a first conductor layer formed on the first surface, and a second conductor layer formed on the second surface; forming a plurality of openings in the first conductor layer that penetrate the first conductor layer and expose the flexible material; forming through holes in the flexible material that reach the second conductor layer by removing the flexible material exposed by each of the openings; forming a conductor layer on the first conductor layer to form a third conductor layer consisting of the first conductor layer and the conductor layer; forming via conductors in each of the through holes that connect the second conductor layer and the third conductor layer; forming a plurality of first circuits on the first surface from the third conductor layer; and forming a plurality of second circuits on the second surface from the second conductor layer to form a spiral coil with the first circuit, the second circuit, and the via conductors.

[Effects of the embodiment]
According to an embodiment of the present invention, a first circuit on a first surface of a flexible material and a second circuit on a second surface of the flexible material are connected by a via conductor penetrating the flexible material. Therefore, the coil substrate can be made thin. A plurality of openings exposing the flexible material are formed in the first conductor layer. Then, by removing the flexible material exposed by each opening, a through hole leading to the second conductor layer is formed in the flexible material. A via conductor is formed in the through hole. The planar shape of the opening formed in the first conductor layer is free. Therefore, via conductors having various shapes can be formed. The shape of the via conductor is represented by the shape on the first surface. For example, the area of the via conductor on the first surface can be increased. The shape of the via conductor can be formed according to the shape of the conductor circuit covering the via conductor. The connection reliability between the via conductor and the conductor circuit covering the via conductor is improved. A coil having a high space factor and high wiring density can be provided.

FIG. 1A is a schematic diagram of a motor according to an embodiment, FIG. 1B is a schematic diagram of a motor coil substrate according to an embodiment, and FIG. 1C is a plan view of wiring. FIG. 2(A) is a plan view of a first surface of a coil substrate of an embodiment, FIG. 2(B) is a plan view of a second surface of the coil substrate, FIG. 2(C) is a schematic diagram showing the overlap of coils, and FIG. 2(D) is a schematic diagram of a via land. 3A to 3E are diagrams showing the manufacturing process of the coil substrate according to the embodiment, FIG. 3F is a plan view of an opening, and FIG. 3G is a plan view of a through hole.

The coil substrate 201 shown in FIG. 2(A) and FIG. 2(B) is prepared. FIG. 2(A) is a plan view of the first surface F of the coil substrate 201 of the embodiment, and FIG. 2(B) is a plan view of the second surface S of the coil substrate 201. The coil substrate 201 includes a flexible material 22 having a first surface F and a second surface S opposite to the first surface F. Furthermore, the coil substrate 201 has coils C (C1 to C6) on the first surface F and the second surface S of the flexible material 22. By winding the coil substrate 201, the motor coil substrate 20 shown in FIG. 1(B) is obtained. For example, the coil substrate 201 is wound in a cylindrical shape. The motor coil substrate 20 is wound around the cavity AH. For example, the shape of the motor coil substrate 20 is a cylinder. The number of windings N is 2 or more and 3 or less. FIG. 1(B) is a schematic diagram.

As shown in FIG. 1(A), a motor 10 is obtained by placing a magnet 48 in a motor coil substrate 20. FIG. 1(A) is a schematic diagram. The motor coil substrate 20 is placed around the magnet 48 via a cavity AH. The arrow MR in FIG. 1(B) indicates the direction of rotation of the motor 10. An example of the motor 10 is a brushless motor. In the embodiment, the magnet 48 rotates, but the motor coil substrate 20 may also rotate.

As shown in Figures 2(A) and 2(B), the flexible material 22 preferably has a short side 20S and a long side 20L. The flexible material 22 has one end 22L and the other end 22R opposite the one end 22L. The one end 22L also serves as the short side 20S. The long side 20L has an upper side 20LU and a lower side 20LD opposite the upper side 20LU. The coils C (C1 to C6) are lined up along the long side 20L of the flexible material 22. The coils C are lined up in a row from one end 22L to the other end 22R of the flexible material 22. The number of coils C is M (number M). The coil closest to the one end 22L is the first coil C1. The coil closest to the other end 22R is the Mth coil CM. The coils C are lined up in order from the first coil C1 to the Mth coil CM. In the examples of Figures 2(A) and 2(B), the number of coils is 6.

The number M of coils C satisfies the following relationship 1.
Relationship 1: M = N x L
For example, L is equal to or greater than 3 and equal to or less than 12. L is a multiple of 3.

The multiple coils C formed on the flexible material 22 are formed simultaneously. For example, the multiple coils C are formed on the flexible material 22 by using a common alignment mark. Therefore, the positions of each coil C are relative to each other.

An example of coil C is shown in FIG. 1(C). Coil C is formed of a central space SC and wiring w surrounding the central space SC. The wiring w has an outer end OE and an inner end IE. The wiring w is formed between the outer end OE and the inner end IE. The wiring w forming coil C is formed in a spiral shape.

As shown in FIG. 1(C), the wiring w includes a plurality of first circuits 51, a plurality of second circuits 52, and a plurality of via conductors VA. The first circuit 51 is formed on the first surface F. The second circuit 52 is formed on the second surface S. The via conductors VA penetrate the flexible material 22. The first circuit 51 and the second circuit 52 are connected through the via conductors VA. One first circuit 51, one second circuit 52, and one via conductor VA form a coil of approximately one turn. Of the wiring w forming one turn, the first circuit 51 is close to one end 22L, and the second circuit 52 is close to the other end 22R. The multiple via conductors VA are divided into a first via conductor VA1 and a second via conductor VA2. The first via conductor VA1 is close to the upper side 20LU, and the second via conductor VA2 is close to the lower side 20LD. The first circuit 51, the second circuit 52, and the via conductor VA are connected in the order of the first circuit 51, the second via conductor VA2, the second circuit 52, and the first via conductor VA1. The wiring w that forms the adjacent turn is connected via the first via conductor VA1.

2D, the first circuit 51 has a first side wall X1 and a second side wall X2 opposite to the first side wall X1. Of the side walls (the first side wall X1 and the second side wall X2) of one first circuit 51, the first side wall X1 is closer to the central space SC.
The second circuit 52 has a third side wall X3 and a fourth side wall X4 opposite to the third side wall X3. Of the side walls (the third side wall X3 and the fourth side wall X4) of one second circuit 52, the third side wall X3 is closer to the central space SC.

In FIG. 2(A) and FIG. 2(B), the wiring w is grouped together. By grouping the first circuits 51 together, a first circuit group 51g is formed. By grouping the second circuits 52 together, a second circuit group 52g is formed.

The coil C in this embodiment is formed using printed wiring board technology. The wiring w that forms the coil C is formed by plating. Alternatively, the wiring w that forms the coil C is formed by etching copper foil. The wiring w that forms the coil C is formed by a semi-additive method, an M-Sap method, or a subtractive method.

The wiring w that forms the coil C is formed using printed wiring board technology. Therefore, the cross-sectional shape of the wiring w is approximately rectangular. According to the embodiment, the space factor of the coil can be increased.

The coil substrate 201 shown in Figures 2(A) and 2(B) has six coils C. The six coils are arranged from one end 22L to the other end 22R. The coils C include a U-phase coil CU, a V-phase coil CV, and a W-phase coil CW. The U-phase coil CU, the V-phase coil CV, and the W-phase coil CW are arranged in the following order: U-phase coil CU, V-phase coil CV, W-phase coil CW. The coil C closest to one end 22L is the U-phase coil CU.

Fig. 2C shows the overlap of the mth coil Cm and the (m+1)th coil Cm+1. m is an integer equal to or greater than 1. When m is 1, the mth coil Cm is the first coil C1, and the (m+1)th coil Cm+1 is the second coil C2. In the example of Fig. 3A, m is 1.
The first circuit group 51g of the (m+1)th coil is located on the central space SC of the mth coil. The density of the wiring w forming the coil C can be increased. The space factor of the coil C can be increased. The torque of the motor can be increased.

FIG. 2D is a schematic diagram of a conductor circuit (via land) VR covering a via conductor VA.
The via land VR has a via land (first land) VRF on the first surface F and a via land (second land) VRS on the second surface S. The first circuit 51 and the second circuit 52 are connected via the first land VRF, the via conductor VA (VA1), and the second surface land VRS. The first circuit 51 includes the first land VRF. The second circuit 52 includes the second land VRS.
An example of the planar shape of the first land VRF is a pentagon. When the planar shape is a pentagon, the interior angles (first interior angle, second interior angle) of two vertices (first vertex A1, second vertex A2) are approximately 90 degrees. The interior angles of vertices other than the first vertex A1 and the second vertex A2 (third vertex A3, fourth vertex A4, fifth vertex A5) are not 90 degrees. The five vertices are arranged in the order of the first vertex A1, the second vertex A2, the third vertex A3, the fourth vertex A4, and the fifth vertex A5. The side between the first vertex A1 and the second vertex A2 is the first side L1. The side between the second vertex A2 and the third vertex A3 is the second side L2. The side between the third vertex A3 and the fourth vertex A4 is the third side L3. The side between the fourth vertex A4 and the fifth vertex A5 is the fourth side L4. The side between the fifth vertex A5 and the first vertex A1 is the fifth side L5. The first side L1 and the long side 20L are substantially parallel. The length of the first side L1 is longer than the length of the second side L2 and the length of the fifth side L5. The length of the second side L2 and the length of the fifth side L5 are substantially equal. The connection reliability between the first circuit 51 and the first land VRF is improved. The connection reliability between the second circuit 52 and the second land VRS is improved. The planar shape of the first land VRF and the planar shape of the second land VRS are similar. The third side L3 is on an extension line of the first side wall X1 of the first circuit 51. The third side L3 is included in a plane including the first side wall X1. Therefore, the connection reliability between the first circuit 51 and the via land VR is improved. The connection reliability between the first circuit 51 and the first land VRF is improved. The fourth side L4 is on an extension line of the third side wall X3 of the second circuit 52. The fourth side L4 is included in the plane including the third side wall X3. Therefore, the connection reliability between the second circuit 52 and the via land VR is improved. The connection reliability between the second circuit 52 and the second land VRS is improved.

The shape of the via conductor VA on the first surface F and the planar shape of the first land VRF are similar. The shape of the via conductor VA on the first surface F and the shape of the first land VRF on the first surface F are the same. When the shape of the via conductor VA on the first surface F is enlarged, the shape of the first land VRF on the first surface F is obtained. The shape of the via conductor VA on the second surface F and the planar shape of the second land VRS are similar. The shape of the via conductor VA on the second surface F and the shape of the second land VRS on the second surface F are the same. When the shape of the via conductor VA on the second surface F is enlarged, the shape of the second land VRS on the second surface F is obtained. This improves the connection reliability between the via conductor VA and the via land VR. The via land VR, the first circuit 51, and the second circuit 52 can be arranged at high density.
The shape of the via conductor VA and the planar shape of the first land VRF on the first surface F are polygonal. The shape of the via conductor VA and the planar shape of the second land VRS on the second surface S are polygonal. The contact area between the via conductor VA and the via land VR can be increased.
The planar shape of the via land VR is a polygon. Examples of the shape are a triangle, a rectangle, a pentagon, and a hexagon. The planar shape of the via conductor VA is a shape of F on the first surface. Or, the planar shape of the via conductor VA is a shape of S on the second surface.

[Manufacturing method]
FIG. 3 shows a method for manufacturing the coil substrate 201 according to the embodiment.
A flexible substrate 22z is prepared ( FIG. 3A ), which is made up of a flexible material 22 having a first surface F and a second surface S opposite to the first surface F, a first conductor layer 31 formed on the first surface F, and a second conductor layer 32 formed on the second surface S. For example, the flexible material 22 is made of polyimide.

A plurality of openings 31a are formed in the first conductor layer 31 so as to penetrate the first conductor layer 31 and expose the flexible material 22 (FIG. 3B). An example of a method for forming the openings 31a is a subtractive method. FIG. 3F shows the planar shape of the openings 31a.
The planar shape of the opening 31a is a pentagon. The opening 31a exposes the flexible material 22. By removing the flexible material 22 exposed by each opening 31a, a through hole 22a leading to the second conductor layer 32 is formed in the flexible material 22 (FIG. 3(C)). For example, the flexible material 22 exposed by the opening 31a is dissolved to form the through hole 22a. An example of a solution for forming the through hole 22a is a strong alkaline solution. FIG. 3(G) is a plan view of the through hole 22a. FIG. 3(G) shows the shape of the through hole 22a on the first surface F. The shape of the through hole 22a is a pentagon. The second conductor layer 32 is exposed by the through hole 22a.

By forming a conductor layer 34 on the first conductor layer 31, a third conductor layer 33 consisting of the first conductor layer 31 and the conductor layer 34 is formed. Via conductors VA connecting the second conductor layer 32 and the third conductor layer 33 are formed in each through hole 22a (Fig. 3(D)). A plurality of first circuits 51 and first lands VRF are formed on the first surface F from the third conductor layer 33. A plurality of second circuits 52 and second lands VRS are formed on the second surface S from the second conductor layer 32 (Fig. 3(E)). A coil C is formed consisting of the first circuits 51, the second circuits 52, the via conductors VA, and the via lands VR.

According to the manufacturing method of the embodiment, a polygonal opening 31a is formed in the first conductor layer 31. Then, by using the first conductor layer 31 as a mask, a through hole 22a is formed in the flexible material 22. Therefore, a through hole 22a of any shape can be formed. A via conductor VA of any shape can be formed. In the manufacturing method of the coil substrate 201 of the embodiment, the contact area between the via conductor VA and the via land VR can be increased. The contact area between the first circuit 51 and the via land VR can be increased. The contact area between the second circuit 52 and the via land VR can be increased.

20 Motor coil substrate 22 Flexible material 48 Magnet 51 First circuit 52 Second circuit
201 coil substrate C coil SC central space VA via conductor

Claims (9)

preparing a flexible substrate including a flexible material having a first surface and a second surface opposite to the first surface, a first conductor layer formed on the first surface, and a second conductor layer formed on the second surface;
forming a plurality of openings in the first conductor layer penetrating the first conductor layer and exposing the flexible material;
removing the flexible material exposed by each of the openings to form through holes in the flexible material leading to the second conductor layer;
forming a conductor layer covering the entire surface of the first conductor layer to form a third conductor layer including the first conductor layer and the conductor layer;
forming a via conductor in each of the through holes to connect the second conductor layer and the third conductor layer;
forming a plurality of first circuits on the first surface from the third conductor layer;
forming a plurality of second circuits on the second surface from the second conductor layer, thereby forming a spiral coil with the first circuits, the second circuits, and the via conductors. A method for manufacturing a coil substrate according to claim 1, in which one of the first circuits, one of the via conductors, and one of the second circuits form a one-turn coil. A method for manufacturing a coil substrate according to claim 1, in which the flexible material is made of polyimide. The method for manufacturing a coil substrate according to claim 1, wherein the planar shape of the opening is polygonal. 5. The method of manufacturing a coil substrate according to claim 4, wherein the first circuit on the first surface includes a wiring and a via land, and the planar shape of the via land is a polygon. A method for manufacturing a coil substrate according to claim 1, in which the through holes are formed by melting the flexible material. A method for manufacturing a coil substrate for a motor, comprising winding a coil substrate manufactured using claim 1. A method for manufacturing a coil substrate according to claim 5, comprising the steps of:
the wiring has a first sidewall and a second sidewall;
A first sidewall of the wiring extending from the via land is on an extension of one side of the polygonal via land. The method for manufacturing a coil substrate according to claim 8, further comprising the steps of:
The polygon is a pentagon.

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