Coil device and actuator

Abstract

To provide a coil device capable of improving thrust without increasing the number of turns in a winding part of wiring or the number of printed wiring boards stacked on one another.SOLUTION: A coil device includes: a coil body; and a ferromagnetic layer. The coil body has a first surface and a second surface opposite to the first surface in the thickness direction of the coil body. The coil body includes at least one printed wiring board. The printed wiring board includes: a base film; and a wiring. The base film has a first main surface and a second main surface opposite to the first main surface in the thickness direction of the base film. The wiring is disposed on at least one of the first main surface and the second main surface, and includes a winding part wound in a spiral shape in plan view. The ferromagnetic layer is arranged only on one of the first surface and the second surface.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a coil device and an actuator. [Background technology]

[0002] For example, Japanese Patent Application Laid-Open No. 2021-174794 (Patent Document 1) describes a coil device. The coil device described in Patent Document 1 has a printed wiring board. The printed wiring board has a base film and wiring. The base film has a first main surface and a second main surface that is the opposite surface to the first main surface. The first main surface and the second main surface form end faces in the thickness direction of the base film. The wiring has a first winding portion that is arranged on the first main surface and is spirally wound in a planar view, and a second winding portion that is arranged on the second main surface and is spirally wound in a planar view. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-174794 Summary of the Invention [Problem to be solved by the invention]

[0004] The coil device described in Patent Document 1 can be used, for example, in an actuator. The actuator has a magnet arranged to face a first main surface. In the actuator, a thrust force is generated by the interaction between a current flowing through a wiring and a magnetic flux from the magnet.

[0005] The above thrust can be improved by increasing the number of turns of the wiring in the winding section or by increasing the number of printed wiring boards arranged in layers. However, increasing the number of turns of the wiring in the winding section increases the length of the wiring (increasing the electrical resistance of the wiring), and the power consumption of the coil device increases. In addition, increasing the number of turns of the wiring in the winding section increases the planar dimensions of the coil device. Furthermore, increasing the number of printed wiring boards arranged in layers increases the height dimension of the coil device.

[0006] The present disclosure has been made in consideration of the above-described problems of the conventional technology, and provides a coil device that can improve thrust without increasing the number of turns in the winding portion of the wiring or the number of printed wiring boards arranged in layers. [Means for solving the problem]

[0007] The coil device of the present disclosure includes a coil body and a ferromagnetic layer. The coil body has a first surface and a second surface opposite the first surface in the thickness direction of the coil body. The coil body has at least one printed wiring board. The printed wiring board has a base film and wiring. The base film has a first main surface and a second main surface opposite the first main surface in the thickness direction of the base film. The wiring is disposed on at least one of the first main surface and the second main surface, and has a winding portion that is spirally wound in a plan view. The ferromagnetic layer is disposed only on either the first surface or the second surface. [Effects of the Invention]

[0008] According to the coil device of the present disclosure, it is possible to improve the thrust without increasing the number of turns in the winding portion of the wiring or the number of printed wiring boards arranged in layers. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a first plan view of the coil device 100. FIG. [Figure 2]FIG. 2 is a second plan view of the coil device 100 as seen from the opposite side to that of FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic cross-sectional view of an actuator 200 using the coil device 100. As shown in FIG. [Figure 5] FIG. 5 is a manufacturing process diagram of the coil device 100. [Figure 6] FIG. 6 is a cross-sectional view illustrating the electroless plating step S2. [Figure 7] FIG. 7 is a cross-sectional view illustrating the resist pattern forming step S3. [Figure 8] FIG. 8 is a cross-sectional view illustrating the electrolytic plating step S4. [Figure 9] FIG. 9 is a cross-sectional view illustrating the resist pattern removing step S5. [Figure 10] FIG. 10 is a cross-sectional view illustrating the etching step S6. [Figure 11] FIG. 11 is a cross-sectional view illustrating the ferromagnetic layer forming step S7. [Figure 12] FIG. 12 is a cross-sectional view of a coil device 100 according to the first modification. [Figure 13] FIG. 13 is a cross-sectional view of a coil device 100 according to the second modification. [Figure 14] FIG. 14 is a cross-sectional view of a coil device 100 according to the third modification. [Figure 15] FIG. 15 is a first explanatory diagram for explaining the effect of the coil device 100. As shown in FIG. [Figure 16] FIG. 16 is a second explanatory diagram for explaining the effect of the coil device 100. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0011] (1) A coil device according to an embodiment includes a coil body and a ferromagnetic layer. The coil body has a first surface and a second surface opposite the first surface in the thickness direction of the coil body. The coil body has at least one printed wiring board. The printed wiring board has a base film and wiring. The base film has a first main surface and a second main surface opposite the first main surface in the thickness direction of the base film. The wiring is disposed on at least one of the first main surface and the second main surface, and has a winding portion that is spirally wound in a planar view. The ferromagnetic layer is disposed only on either the first surface or the second surface.

[0012] According to the coil device of (1) above, it is possible to improve the thrust without increasing the number of turns in the winding portion of the wiring or the number of printed wiring boards arranged in layers.

[0013] (2) In the coil device of (1) above, the ferromagnetic layer may be a plating layer made of a ferromagnetic material.

[0014] (3) In the coil device of (2) above, the plating layer may be an electrolytic plating layer.

[0015] (4) In the coil device of (2) or (3) above, the ferromagnetic material may contain nickel.

[0016] (5) The coil device of (1) above may further include an adhesive layer. The ferromagnetic layer may be attached to only one of the first surface and the second surface via the adhesive layer.

[0017] (6) In the coil device of (5) above, the ferromagnetic layer may be a plate-like body made of a ferromagnetic material.

[0018] (7) In the coil device of (6) above, the ferromagnetic material may be an iron-based alloy containing ferrite or martensite.

[0019] (8) In the coil device of (1) above, the ferromagnetic layer may be made up of a resin layer and a filler that is contained in the resin layer and is made of a ferromagnetic material.

[0020] (9) In the coil device of (8) above, the resin layer may be formed of a solder resist.

[0021] (10) An actuator according to an embodiment includes a magnet and the coil device according to any one of (1) to (9) above. In the coil device, a ferromagnetic layer is disposed only on the second surface. The magnet is disposed opposite the first surface.

[0022] According to the actuator of (10) above, the thrust can be increased without increasing the number of turns in the winding portion of the wiring or the number of printed wiring boards arranged in layers.

[0023] [Details of the embodiments of the present disclosure] The details of the embodiment of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are given the same reference numerals, and redundant description will not be repeated. The coil device according to the embodiment is referred to as coil device 100.

[0024] (Configuration of coil device 100) The configuration of the coil device 100 will be described below.

[0025] FIG. 1 is a first plan view of the coil device 100. FIG. 2 is a second plan view of the coil device 100 as viewed from the opposite side to that of FIG. 1. In FIGS. 1 and 2, the ferromagnetic layer 30, the protective layer 40, and the protective layer 50 are omitted. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. As shown in FIGS. 1 to 3, the coil device 100 has a coil body 10 and a ferromagnetic layer 30.

[0026] The coil body 10 has at least one printed wiring board 20. In the example shown in Figures 1 to 3, there is one printed wiring board 20. The printed wiring board 20 has a base film 21 and wiring 22.

[0027] The base film 21 has a main surface 21a and a main surface 21b. The main surface 21b is the surface opposite to the main surface 21a. The main surfaces 21a and 21b are end surfaces of the base film 21 in the thickness direction. The base film 21 is made of a material such as polyimide. However, the material of the base film 21 is not limited to this.

[0028] The wiring 22 is arranged on the main surfaces (main surface 21a, main surface 21b) of the base film 21. The wiring 22 has a winding portion 22a and a winding portion 22b. The winding portion 22a is arranged on the main surface 21a. The winding portion 22b is arranged on the main surface 21b. The wiring 22 is wound in a spiral shape in the winding portion 22a and the winding portion 22b when viewed from the main surface 21a side along the normal direction to the main surface 21a or when viewed from the main surface 21b side along the normal direction to the main surface 21b (plan view). The winding portion 22a and the winding portion 22b are arranged to overlap in plan view.

[0029] The wiring 22 has lands 22c, 22d, 22e, and 22f. Lands 22c and 22d are arranged on the main surface 21a. Lands 22e and 22f are arranged on the main surface 21b. Lands 22c and 22d are connected to the outermost and innermost parts of the winding portion 22a, respectively. Lands 22e and 22f are connected to the innermost and outermost parts of the winding portion 22b. Lands 22d and 22e are arranged to overlap in a plan view.

[0030] The wiring 22 has, for example, a seed layer 23, an electroless plated layer 24, and an electrolytic plated layer 25. The seed layer 23 is disposed on the main surfaces (main surfaces 21a and 21b) of the base film 21. The constituent material of the seed layer 23 is, for example, a nickel-chromium alloy. However, the constituent material of the seed layer 23 is not limited to this. The electroless plated layer 24 is disposed on the seed layer 23. The electroless plated layer 24 is a layer formed by an electroless plating method. The constituent material of the electroless plated layer 24 is, for example, copper or a copper alloy.

[0031] Although not shown, through holes are formed in the base film 21 and the seed layer 23. These through holes are formed so as to overlap the lands 22d and 22e in a plan view. The electroless plating layer 24 is also disposed on the inner wall surfaces of these through holes. This electrically connects the portions of the wiring 22 on the main surface 21a and the portions of the wiring 22 on the main surface 21b.

[0032] Electrolytic plated layer 25 is disposed on electroless plated layer 24. Electrolytic plated layer 25 is a layer formed by electrolytic plating. Electrolytic plated layer 25 is made of, for example, copper or a copper alloy.

[0033] The coil body 10 has a first surface 10a and a second surface 10b. The second surface 10b is the surface opposite to the first surface 10a. The first surface 10a and the second surface 10b are end surfaces of the coil body 10 in the thickness direction. As described above, in the example shown in FIGS. 1 to 3, the coil body 10 is formed from a single printed wiring board 20, and therefore the first surface 10a is formed from the main surface 21a and the surface of the portion of the wiring 22 arranged on the main surface 21a, and the second surface 10b is formed from the main surface 21b and the surface of the portion of the wiring 22 arranged on the main surface 21b.

[0034] The ferromagnetic layer 30 is a layer containing a ferromagnetic material. The ferromagnetic layer 30 is, for example, a plating layer 31. The ferromagnetic layer 30 (plating layer 31) is disposed only on the second surface 10b. From another perspective, the ferromagnetic layer 30 (plating layer 31) is not disposed on the first surface 10a. More specifically, the plating layer 31 is disposed on the main surface 21b between portions of adjacent wirings 22 and covers the surfaces of the portions of wirings 22 on the main surface 21b. Note that, to prevent short-circuiting of the wirings 22, the plating layer 31 on the main surface 21b between portions of adjacent wirings 22 is separated from the plating layer 31 covering the surfaces of the portions of wirings 22 on the main surface 21b. Note that the ferromagnetic layer 30 may be disposed only on the first surface 10a.

[0035] The plating layer 31 is a layer formed by electroless plating or electrolytic plating. The constituent material of the plating layer 31 is a ferromagnetic material. The ferromagnetic material constituting the plating layer 31 may contain nickel. However, the ferromagnetic material constituting the plating layer 31 is not limited to this. When the plating layer 31 is formed by electrolytic plating, the constituent material of the plating layer 31 is more likely to crystallize than when it is formed by electroless plating, and stronger ferromagnetism is exhibited.

[0036] The coil device 100 further has a protective layer 40 and a protective layer 50. The protective layer 40 has an adhesive layer 41 and a base film 42. The adhesive layer 41 is disposed on the main surface 21a so as to cover the portion of the wiring 22 on the main surface 21a. The adhesive layer 41 is made of an adhesive. The base film 42 is disposed on the adhesive layer 41. The base film 42 is made of a material such as polyimide. However, the materials of the adhesive layer 41 and the base film 42 are not limited to this.

[0037] The protective layer 50 has an adhesive layer 51 and a base film 52. The adhesive layer 51 is disposed on the main surface 21b with the plating layer 31 interposed therebetween so as to cover the portions of the wiring 22 on the main surface 21b. The adhesive layer 51 is made of an adhesive. The base film 52 is disposed on the adhesive layer 51. The base film 52 is made of a material such as polyimide. However, the materials of the adhesive layer 51 and the base film 52 are not limited to these.

[0038] Fig. 4 is a schematic cross-sectional view of an actuator 200 using the coil device 100. As shown in Fig. 4, the actuator 200 has the coil device 100 and a magnet 110. The magnet 110 is arranged so as to face the first surface 10a. From another perspective, this means that the ferromagnetic layer 30 is arranged only on the side opposite to the magnet 110.

[0039] In the actuator 200, a voltage is applied between the land 22c and the land 22f, causing a current to flow through the wiring 22. A magnetic flux generated by the magnet 110 interacts with the current flowing through the wiring 22, causing a thrust force to be generated in the coil device 100. In the actuator 200, a component of this thrust force in a direction parallel to the main surface 21a (main surface 21b) is utilized.

[0040] (Manufacturing method of coil device 100) A method for manufacturing the coil device 100 will be described below.

[0041] Fig. 5 is a manufacturing process diagram of the coil device 100. As shown in Fig. 5, the manufacturing method of the coil device 100 includes a preparation step S1, an electroless plating step S2, a resist pattern formation step S3, an electrolytic plating step S4, a resist pattern removal step S5, an etching step S6, a ferromagnetic layer formation step S7, and a protective layer formation step S8.

[0042] In the preparation step S1, a base film 21 is prepared. The base film 21 prepared in the preparation step S1 has a seed layer 23 disposed on its main surfaces (main surfaces 21a and 21b).

[0043] 6 is a cross-sectional view illustrating the electroless plating step S2. As shown in FIG. 6, in the electroless plating step S2, an electroless plated layer 24 is formed on the seed layer 23 by an electroless plating method. After the preparation step S1 and before the electroless plating step S2, a through hole is formed in the base film 21 and the seed layer 23. Therefore, in the electroless plating step S2, the electroless plated layer 24 is also formed on the inner wall surface of the through hole.

[0044] 7 is a cross-sectional view illustrating the resist pattern forming step S3. As shown in FIG. 7, in the resist pattern forming step S3, a resist pattern 60 is formed on the electroless plated layer 24. The resist pattern 60 is formed, for example, by applying a dry film resist to the electroless plated layer 24 and then exposing and developing the applied dry film resist. The resist pattern 60 has an opening 61. The electroless plated layer 24 is exposed through the opening 61.

[0045] Fig. 8 is a cross-sectional view illustrating the electrolytic plating step S4. As shown in Fig. 8, in the electrolytic plating step S4, an electrolytic plating layer 25 is formed on the electroless plated layer 24 exposed from the opening 61 by electroplating. Fig. 9 is a cross-sectional view illustrating the resist pattern removal step S5. As shown in Fig. 9, in the resist pattern removal step S5, the resist pattern 60 is removed.

[0046] 10 is a cross-sectional view illustrating the etching step S6. As shown in FIG. 10, in the etching step S6, the electroless plating layer 24 and the seed layer 23 that were present under the resist pattern 60 are removed by etching. In this manner, in the manufacturing method of the coil device 100, the wiring 22 is formed by, for example, a semi-additive method.

[0047] 11 is a cross-sectional view illustrating the ferromagnetic layer forming step S7. As shown in FIG. 11, in the ferromagnetic layer forming step S7, the ferromagnetic layer 30, more specifically, the plating layer 31, is formed on the second surface 10b (the main surface 21b between the portions of the adjacent wirings 22 and the surfaces of the wirings 22 on the main surface 21b) by electroless plating or electrolytic plating. The plating layer 31 may be formed by, for example, sputtering or vapor deposition.

[0048] In the protective layer forming step S8, the protective layer 40 and the protective layer 50 are formed. In the protective layer forming step S8, first, the protective layer 40 and the protective layer 50 are prepared. At this stage, the adhesive layer 41 and the adhesive layer 51 are uncured. Second, the protective layer 40 is arranged so that the adhesive layer 41 covers the portion of the wiring 22 on the main surface 21a. Furthermore, the protective layer 50 is arranged so that the adhesive layer 51 covers the portion of the wiring 22 on the main surface 21b, with the plating layer 31 interposed therebetween. Third, while being heated, the base film 42 and the base film 52 are pressed toward the printed wiring board 20. This causes the adhesive layer 41 and the adhesive layer 51 to cure. In this manner, the structure of the coil device 100 shown in FIGS. 1 to 3 is formed.

[0049] (Variation 1) Fig. 12 is a cross-sectional view of a coil device 100 according to Modification 1. As shown in Fig. 12, in the coil device 100, the coil body 10 may have a plurality of printed wiring boards 20. In the example shown in Fig. 12, the number of printed wiring boards 20 included in the coil body 10 is three. However, the number of printed wiring boards 20 included in the coil body 10 may be two, or four or more.

[0050] 12, the three printed wiring boards 20 included in the coil body 10 are designated as printed wiring board 20A, printed wiring board 20B, and printed wiring board 20C. Printed wiring board 20A, printed wiring board 20B, and printed wiring board 20C are stacked in the thickness direction of the coil body 10. More specifically, printed wiring board 20B is disposed so that main surface 21b of printed wiring board 20B faces main surface 21a of printed wiring board 20A. Furthermore, printed wiring board 20C is disposed so that main surface 21a of printed wiring board 20C faces main surface 21b of printed wiring board 20A.

[0051] In printed wiring board 20A, wiring 22 is arranged on principal surface 21a and principal surface 21b, with the portion of wiring 22 on principal surface 21a having winding portion 22a and the portion of wiring 22 on principal surface 21b having winding portion 22b. In printed wiring board 20B, wiring 22 is arranged only on principal surface 21a, with the portion of wiring 22 on principal surface 21a having winding portion 22a. In printed wiring board 20C, wiring 22 is arranged only on principal surface 21b, with the portion of wiring 22 on principal surface 21b having winding portion 22b.

[0052] Printed wiring board 20B is bonded to printed wiring board 20A by adhesive layer 70 disposed between printed wiring board 20A and printed wiring board 20B. Similarly, printed wiring board 20C is bonded to printed wiring board 20C by adhesive layer 71 disposed between printed wiring board 20A and printed wiring board 20C. When coil body 10 is composed of printed wiring boards 20A, 20B, and 20C, first surface 10a is composed of main surface 21a of printed wiring board 20A and partial surfaces of wiring 22 disposed on main surface 21a, and second surface 10b is composed of main surface 21b of printed wiring board 20C and partial surfaces of wiring 22 disposed on main surface 21b.

[0053] (Variation 2) Fig. 13 is a cross-sectional view of a coil device 100 according to Modification 2. As shown in Fig. 13, the coil device 100 does not necessarily have a plating layer 31, and has a plate-like body 32 as the ferromagnetic layer 30. The plate-like body 32 is disposed on the adhesive layer 51 instead of the base film 52. Therefore, in this case as well, the magnetic layer 30 is disposed only on the second surface 10b.

[0054] The plate-shaped body 32 is made of a ferromagnetic material. The plate-shaped body 32 is, for example, a martensitic or ferritic stainless steel plate or a ferrite plate. That is, a specific example of the ferromagnetic material constituting the plate-shaped body 32 is an iron-based alloy containing martensite or ferrite. However, the ferromagnetic material constituting the plate-shaped body 32 is not limited to this. The thickness of the plate-shaped body 32 is not particularly limited. Even if the plate-shaped body 32 is thin and has a foil or layer shape, it is still considered to be a plate-shaped body 32.

[0055] In this case, the ferromagnetic layer forming step S7 is not performed to form the plating layer 31, and the ferromagnetic layer forming step S7 is performed by attaching the plate-shaped body 32 instead of the base film 52 in the protective layer forming step S8.

[0056] (Variation 3) Fig. 14 is a cross-sectional view of a coil device 100 according to Modification 3. As shown in Fig. 14, the coil device 100 does not necessarily have the plating layer 31 and the protective layer 50, and instead has a resin layer 33 as the ferromagnetic layer 30. The resin layer 33 is disposed on the main surface 21b so as to cover the portion of the wiring 22 on the main surface 21b. That is, in this case as well, the ferromagnetic layer 30 is disposed only on the second surface 10b.

[0057] The resin layer 33 is formed of, for example, solder resist. However, the constituent material of the resin layer 33 is not limited to this. The resin layer 33 also contains a filler. The filler is formed of a ferromagnetic material. The content of the filler is adjusted so as to prevent short circuits from occurring between adjacent portions of the wiring 22.

[0058] In this case, the ferromagnetic layer forming step S7 is not performed to form the plating layer 31, and the protective layer 50 is not formed in the protective layer forming step S8. Instead, a separate step is performed in which a constituent material of the resin layer 33 containing a filler made of a ferromagnetic material is applied to the main surface 21b so as to cover the portions of the wiring 22 on the main surface 21b, and the applied constituent material of the resin layer 33 is heat-cured.

[0059] (Effects of the coil device 100) The effects of the coil device 100 will be described below.

[0060] 15 is a first explanatory diagram illustrating the effect of the coil device 100. As shown in FIG. 15, when the coil device 100 does not have the ferromagnetic layer 30 (plating layer 31), the direction of the magnetic flux from the magnet 110 that interacts with the current flowing through the wiring 22 has a large inclination angle with respect to the normal direction of the main surface 21a (main surface 21b). Therefore, the inclination angle of the direction of the thrust force acting on the coil device 100 with respect to the normal direction of the main surface 21a (main surface 21b) also becomes large. As a result, the component of the thrust force in the direction parallel to the main surface 21a (main surface 21b) becomes smaller.

[0061] FIG. 16 is a second explanatory diagram illustrating the effects of the coil device 100. As shown in FIG. 16, when the coil device 100 has a ferromagnetic layer 30 (plating layer 31), the direction of the magnetic flux from the magnet 110 that interacts with the current flowing through the wiring 22 has a smaller inclination angle with respect to the normal direction of the main surface 21 a (main surface 21 b). Therefore, the inclination angle of the direction of the thrust acting on the coil device 100 with respect to the normal direction of the main surface 21 a (main surface 21 b) also becomes smaller, and the component of the thrust in the direction parallel to the main surface 21 a (main surface 21 b) becomes larger. In this way, the coil device 100 can increase the thrust acting on the coil device 100 without increasing the number of turns of the wiring 22 or the number of printed wiring boards 20 arranged on top of each other.

[0062] When the ferromagnetic layer 30 is disposed on the first surface 10a, the wiring 22 is located on the opposite side of the ferromagnetic layer 30 from the magnet 110. Therefore, the magnetic flux from the magnet 110 is shielded by the ferromagnetic layer 30, and the thrust acting on the coil device 100 is actually reduced.

[0063] (Example) In order to confirm the effect of the coil device 100, Samples 1 to 6 of the coil device were prepared. Sample 1 is a sample that uses a plating layer 31 as the ferromagnetic layer 30. Samples 2 and 3 are samples that use a plate-shaped body 32 as the ferromagnetic layer 30. In Sample 2, a stainless steel plate was used as the plate-shaped body 32, and in Sample 3, a ferrite plate was used as the plate-shaped body 32. Sample 4 is a sample that uses a resin layer 33 as the ferromagnetic layer 30.

[0064] Sample 5 is a sample that does not have a ferromagnetic layer 30. Sample 6 does not have a ferromagnetic layer 30, and the coil body 10 is composed of printed wiring board 20A, printed wiring board 20B, and printed wiring board 20C. That is, Samples 1 to 4 correspond to coil device 100, but Samples 5 and 6 do not correspond to coil device 100. Also, in Samples 1 to 5, the winding portion (coil) composed of wiring 22 is formed in two layers, but in Sample 6, the winding portion (coil) composed of wiring 22 is formed in four layers. Note that the number of turns of wiring 22 in the winding portion for each layer was the same in Samples 1 to 6.

[0065] The thrust component parallel to the main surface 21a (main surface 21b) was calculated by simulation for Samples 1 to 6. The results of this simulation are shown in Table 1. The thrust component parallel to the main surface 21a (main surface 21b) for each sample is shown at a magnification relative to Sample 5.

[0066] [Table 1]

[0067] As shown in Table 1, a comparison of Sample 1 with Sample 5 and Sample 6 shows that the thrust component parallel to the main surface 21a (main surface 21b) in Sample 1 was larger than the thrust component parallel to the main surface 21a (main surface 21b) in Sample 5, and was comparable to the thrust component parallel to the main surface 21a (main surface 21b) in Sample 6. This comparison reveals that in Sample 1, by arranging the ferromagnetic layer 30 only on the second surface 10b side, the thrust is improved without increasing the number of turns of the wiring 22 or the number of stacked printed wiring boards 20.

[0068] Furthermore, a comparison of Samples 2 to 4 with Sample 5 revealed that the thrust component parallel to the main surface 21a (main surface 21b) in Samples 2 to 4 was larger than the thrust component parallel to the main surface 21a (main surface 21b) in Sample 5. This reveals that the thrust can also be improved when the plate-shaped body 32 or the resin layer 33 is used as the ferromagnetic layer 30, without increasing the number of turns of the wiring 22 or the number of stacked printed wiring boards 20.

[0069] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims rather than the above embodiments, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0070] 10 Coil body 10a 1st page 10b 2nd side 20, 20A, 20B, 20C Printed wiring board 21 Base film 21a,21b Main surface 22 Wiring 22a, 22b Winding section 22c, 22d, 22e, 22f Land 23 Seed Layer 24 Electroless plating layer 25 Electroplated layer 30 Magnetic layer 31 plating layer 32 Plate-shaped body 33 Resin layer 40 protective layer 41 Adhesive layer 42 Base film 50 protective layer 51 Adhesive layer 52 Base film 60 Resist Pattern 61 Aperture 70,71 Adhesive layer 100 Coil device 110 Magnet 200 Actuator S1 Preparation process S2 Electroless plating process S3 Resist pattern formation process S4 Electrolytic plating process S5 Resist pattern removal process S6 Etching process S7 Ferromagnetic layer formation process S8 Protective layer formation process

Claims

1. A coil body; a ferromagnetic layer; the coil body has a first surface and a second surface opposite to the first surface in a thickness direction of the coil body, the coil body has at least one printed wiring board; The printed wiring board has a base film and wiring, The base film has a first main surface and a second main surface opposite to the first main surface in a thickness direction of the base film, the wiring has a winding portion that is disposed on at least one of the first main surface and the second main surface and that is wound in a spiral shape in a plan view, The ferromagnetic layer is disposed only on either the first surface or the second surface.

2. The coil device according to claim 1 , wherein the ferromagnetic layer is a plating layer made of a ferromagnetic material.

3. The coil device according to claim 2 , wherein the plating layer is an electrolytic plating layer.

4. The coil device of claim 3 , wherein the ferromagnetic material includes nickel.

5. Further comprising an adhesive layer, The coil device according to claim 1 , wherein the ferromagnetic layer is attached to only one of the first surface and the second surface with the adhesive layer interposed therebetween.

6. The coil device according to claim 5 , wherein the ferromagnetic layer is a plate-like body made of a ferromagnetic material.

7. The coil device according to claim 6 , wherein the ferromagnetic material is an iron-based alloy containing ferrite or martensite.

8. The coil device according to claim 1 , wherein the ferromagnetic layer is made up of a resin layer and a filler contained in the resin layer and made of a ferromagnetic material.

9. The coil device according to claim 8 , wherein the resin layer is a solder resist layer.

10. A magnet and The coil device according to any one of claims 1 to 9, In the coil device, the ferromagnetic layer is disposed only on the second surface, The magnet is disposed opposite the first surface.

Images