JP7562382B2 - Coil device and method for manufacturing the same - Google Patents

Description

The present invention relates to a coil device and a manufacturing method thereof.

As electronic devices such as smartphones become more sophisticated and operate at higher frequencies, there is an increasing demand for miniaturization of electronic components such as coil devices mounted on these electronic devices. One known technology for miniaturizing coil devices is described in Patent Document 1. Patent Document 1 describes a method for manufacturing a coil device in which a plating layer is formed on the surface of a cylindrical rod made of a ceramic magnetic material, and a spiral coil is formed by laser processing the plating layer. This manufacturing method of forming a coil pattern by laser processing makes it possible to form a small-sized coil, thereby enabling the miniaturization of the coil device.

However, due to their characteristics, ceramic magnetic bodies are prone to damage such as bending and cracking (low strength). For example, when cutting a long ceramic magnetic body to produce multiple individual cylindrical rods, the ceramic magnetic body may be damaged due to bending, etc., and the yield may decrease. For this reason, the manufacturing method described in Patent Document 1 is not suitable for mass production of small coil devices.

Japanese Patent Application Publication No. 6-120062

The present invention was made in consideration of these circumstances, and its purpose is to provide a coil device that is small and suitable for mass production, and a manufacturing method thereof.

In order to achieve the above object, a method for manufacturing a coil device according to the present invention includes the steps of:
A step of forming a coil pattern by patterning the surface of the conductive yarn having a conductive layer formed on the surface of the insulating fiber;
and providing terminal portions at ends of the coil pattern.

The manufacturing method of the coil device according to the present invention includes a step of forming a coil pattern by patterning the surface of the conductive thread having a conductive layer formed on the surface of the insulating fiber. Since the conductive thread is made of insulating fibers, it is highly flexible and has durability (flex resistance) against repeated bending. Therefore, even if the conductive thread is subjected to a load due to bending or folding during the coil pattern formation stage, it is unlikely to be damaged by breaking or cracking (high strength). Therefore, it is possible to prevent a decrease in yield caused by damage to the conductive thread, and it is possible to mass-produce individual pieces of conductive thread with a coil pattern formed thereon, for example, by dividing a long conductive thread into individual pieces. Therefore, according to the manufacturing method of the coil device according to the present invention, it is possible to mass-produce small coil devices with high efficiency.

In addition, in conventional technology, a process is performed to mold the ceramic magnetic body into a cylindrical shape, and if dimensional accuracy is to be ensured, the management burden in terms of process and equipment increases, which can lead to high manufacturing costs. In contrast, the coil device of the present invention, unlike conventional technology, does not perform a process to mold the ceramic magnetic body into a cylindrical shape, and the above-mentioned problems do not occur.

Preferably, the method further includes a step of cutting the conductive thread that has been subjected to the pattern processing to a predetermined length to form individual pieces of the conductive thread. With this configuration, it is possible to obtain multiple individual pieces of conductive thread from one conductive thread, and individual pieces of conductive thread with coil patterns formed thereon can be mass-produced with high efficiency.

Preferably, the conductive thread is made of a single thread of the insulating fiber with the conductive layer formed on its surface. This configuration makes it easy to form a conductive layer on the surface of the insulating fiber, facilitating the formation of a coil pattern.

The conductive thread may be composed of a bundle of insulating fiber threads with the conductive layer formed on the surface. Such conductive threads have excellent flexibility and bending resistance, and can effectively prevent a decrease in yield caused by damage to the conductive thread.

The insulating fiber is preferably made of a synthetic resin. One example of a synthetic resin is aramid fiber. Aramid fiber has a relatively low dielectric constant and dielectric tangent (tan δ), and a relatively high heat resistance. Therefore, by using a synthetic resin with such characteristics as the insulating fiber, it is possible to mass-produce small coil devices that have good high-frequency characteristics and high heat resistance with high efficiency.

Preferably, the method further includes a step of covering the conductive thread that has been subjected to the pattern processing with resin. With this configuration, the conductive thread can be effectively protected with resin, and terminal electrodes for connecting the coil device to an external circuit can be provided on the resin-coated portion.

Preferably, the pattern processing is performed by laser trimming. With this configuration, it becomes possible to precisely pattern the surface of the conductive layer formed on the surface of the conductive thread, and the coil pattern can be formed with high precision on the surface of the conductive layer.

Preferably, the heat resistance temperature of the insulating fiber is 200°C or higher. With this configuration, it is possible to manufacture a coil device with high heat resistance that can withstand the solder reflow temperature.

In order to achieve the above object, the coil device according to the present invention has a core material made of insulating fibers. Insulating fibers have excellent flexibility and bending resistance, and are less likely to be damaged. Furthermore, long insulating fibers can be diced to produce a large number of individual pieces of insulating fibers. Therefore, by using insulating fibers having the above characteristics as a core material, it is possible to prevent a decrease in yield due to damage to the core material in the manufacturing process of the coil device, and it is also possible to produce a large number of small core materials. Therefore, according to the coil device according to the present invention, it is possible to realize a coil device that is small and suitable for mass production.

Preferably, the insulating fiber has a conductive thread in which a conductive layer is formed on the surface thereof, and a coil pattern made of the conductive layer.

As mentioned above, conductive thread has excellent flexibility and bending resistance, and is not easily damaged. Therefore, it is possible to prevent a decrease in yield due to damage to the conductive thread. For example, by dividing a long conductive thread into individual pieces, individual pieces of conductive thread with coil patterns formed thereon can be mass-produced with high efficiency, and small coil devices can be obtained in large quantities based on these individual pieces.

The coil device according to the present invention can be transformed into any shape by taking advantage of its flexibility. For example, depending on the application, the conductive thread can be bent into various shapes such as a C-shape or a ring shape, and the coil device having the conductive thread can be placed on a substrate and connected to an external circuit.

FIG. 1 is a perspective view of a coil device according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view of the coil device shown in FIG. FIG. 3 is a vertical sectional view of the coil device shown in FIG. Fig. 4A is a perspective view showing the configuration of the conductive thread shown in Fig. 2. In Fig. 4A, the configuration of the core material is shown at the top, and a cross-sectional view of the conductive thread is shown at the bottom. Fig. 4B is a perspective view showing the configuration of the conductive thread of the coil device according to the second embodiment of the present invention. In Fig. 4B, the configuration of the core material is shown at the top, and a cross-sectional view of the conductive thread is shown at the bottom. Fig. 4C is a perspective view showing the configuration of a conductive thread of a coil device according to a third embodiment of the present invention. In Fig. 4C, the configuration of a core material is shown at the top, and a cross-sectional view of the conductive thread is shown at the bottom. 5A to 5C are diagrams illustrating a method for manufacturing the coil device shown in FIG. FIG. 6 is a vertical sectional view showing a modification of the coil device shown in FIG. FIG. 7 is a perspective view showing a method for manufacturing the coil device shown in FIG. 4B. FIG. 8 is a cross-sectional view showing a process subsequent to the process shown in FIG. FIG. 9 is a cross-sectional view showing a process subsequent to the process shown in FIG. FIG. 10 is a perspective view showing a step subsequent to the step shown in FIG. FIG. 11 is a cross-sectional view showing an individual piece of the resin molding formed by the process shown in FIG.

The present invention will now be described based on the embodiments shown in the drawings.

1 and 2, a coil device 10 according to a first embodiment of the present invention has a substantially rectangular parallelepiped shape, and includes a core portion 20, a first external terminal 31, a second external terminal 32, and a coil portion 40. The coil device 10 is an inductor element mounted on an electronic device such as a smartphone, and is particularly suitable for use in high frequency bands.

The length of the coil device 10 in the X-axis direction is preferably 0.2 to 5.0 mm, the length of the coil device 10 in the Y-axis direction is preferably 0.1 to 2.5 mm, and the length of the coil device 10 in the Z-axis direction is preferably 0.1 to 2.5 mm. However, the size of the coil device 10 is not limited to this, and may be larger (or smaller) than the above sizes. The coil device 10 in this embodiment is, for example, 0402 size with planar dimensions of 0.4 mm x 0.2 mm, or 0603 size with planar dimensions of 0.6 mm x 0.3 mm.

As shown in FIG. 2, the core portion 20 is made of an exterior material containing resin, and covers (coats) the coil portion 40 so as to surround it. The core portion 20 has an external shape of a roughly rectangular parallelepiped with its long sides in the X-axis direction, and has a through hole (cavity) inside. The coil portion 40 can be housed inside this through hole. The coil portion 40 may be provided inside the through hole so that it can be inserted and removed, or the coil portion 40 may be provided so that it is integrated with the core portion 20.

The core portion 20 may be made of resin only, or may contain a magnetic material. The resin contained in the core portion 20 is not particularly limited, but examples include thermoplastic resins such as fluororesin (PTFE, etc.), acrylic resin, liquid crystal polymer, and polyamide, and thermosetting resins such as epoxy resin, phenolic resin, melamine resin, silicone resin, urethane resin, and polyimide resin.

When the core portion 20 contains a magnetic material, the magnetic material contained in the core portion 20 is not particularly limited, but examples thereof include metal magnetic materials and ferrites. Examples of metal magnetic materials are not particularly limited, but examples thereof include Fe-Ni alloy powder, Fe-Si alloy powder, Fe-Si-Cr alloy powder, Fe-Co alloy powder, Fe-Si-Al alloy powder, and amorphous iron. Examples of ferrites include Ni-Zn ferrites and Mn-Zn ferrites.

As shown in FIG. 1, the first external terminal 31 is provided on one side of the core portion 20 in the X-axis direction, and the second external terminal 32 is provided on the other side of the core portion 20 in the X-axis direction. The first external terminal 31 is a substantially L-shaped metal terminal and is attached to the core portion 20 so as to straddle the end face on one side in the X-axis direction and part of the bottom face. The second external terminal 32 is a substantially L-shaped metal terminal and is attached to the core portion 20 so as to straddle the end face on the other side in the X-axis direction and part of the bottom face.

As shown in FIG. 2, the coil portion 40 is made of conductive thread 50. In this embodiment, the coil portion 40 is formed by patterning the surface of the conductive thread 50. The conductive thread 50 is made of a thin conductive thread that is flexible and has high strength and low resistance, and has a generally cylindrical shape that is long in the X-axis direction. The conductive thread 50 has excellent bending resistance and flexibility, and is configured to be freely bent (foldable) in a direction perpendicular to the X-axis direction.

The conductive thread 50 has a core material 51, a conductive layer 52, and a terminal portion 53. The core material 51 is made of insulating fibers made of nonwoven fabric, and the insulating fibers are made of synthetic resin. In this embodiment, aramid fibers made of aramid resin are used as the insulating fibers.

Aramid fibers are known as a material that exhibits excellent fiber characteristics, such as high strength, high elasticity (high elastic limit, low elastic modulus), and high heat resistance. Aramid resin also has a small dielectric constant and dielectric tangent (tan δ), and can be suitably used as a base material for electronic components that are expected to be used in the high frequency band, such as the coil device 10 in this embodiment. Furthermore, since aramid fibers made of aramid resin have a color that is close to transparent, when laser trimming is performed on the conductive layer 52 formed on the surface of the aramid fibers as described below, the laser light easily passes through them and they are not easily damaged by the laser light.

The insulating fibers constituting the core material 51 are not limited to aramid fibers, and insulating fibers made of other synthetic resins may be used. Examples of other synthetic resin materials include fluororesins, polyimide resins, liquid crystal polymers, phenols, polyesters, and nylons. From the viewpoint of heat resistance, fluororesins, polyimide resins, liquid crystal polymers, and phenols are preferable. Bismaleimide may be used as the polyimide resin, and novoloid may be used as the phenol. These materials may be used alone or in combination of two or more. By using synthetic resins made of the above-mentioned materials to form insulating fibers, it is possible to form a core material 51 having a small dielectric constant and dielectric loss tangent (tan δ) and a high tensile strength and tensile modulus. In addition, it is preferable that the insulating fibers be capable of being metal-plated on the surface as described below.

As a characteristic of the synthetic resin constituting the core material 51, the relative dielectric constant at 1 GHz or more and 90 GHz or less is preferably 4.0 or less, more preferably 3.5 or less, and particularly preferably 3.0 or less. In addition, the dielectric loss tangent (tan δ) at 1 GHz or more and 90 GHz or less is preferably 0.03 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less.

In addition, the aspect ratio (length/width or length/diameter) of the core material 51 is preferably 100 or more.

The heat resistance temperature (or decomposition temperature or melting temperature) of the insulating fiber is preferably a temperature that can withstand the reflow temperature of the solder, preferably 200°C or higher, and more preferably 230°C or higher.

As shown in FIG. 4A, the conductive thread 50 is made of a single insulating fiber thread (core material 51) with a conductive layer 52 formed on the surface. The core material 51 may be a single-twisted thread with a right or left twist. Since the core material 51 is made of a thread made of synthetic resin, it has a stable shape (a shape with few defects) and a constant diameter at each position along its length.

The diameter L of the core material 51 may be appropriately determined according to the external dimensions of the coil device 10. For example, a core material 51 of about 100 μm can be used. The present invention is suitable for so-called extremely small size parts, such as 0402 size coil device 10 with planar dimensions of 0.4 mm x 0.2 mm, or 0603 size coil device 10 with planar dimensions of 0.6 mm x 0.3 mm, and the diameter of the core material 51 applied to these extremely small size parts is preferably 5 to 15 μm, and more preferably 8 to 12 μm. The core material 51 is obtained, for example, by cutting a long thread to a predetermined length. The length of the core material 51 in the X-axis direction is approximately the same as or shorter than the length of the coil device 10 in the X-axis direction.

The conductive layer 52 is formed on the surface of the core material 51 (insulating fiber). The conductive layer 52 covers the outer peripheral surface of the core material 51 and has a generally ring-shaped cross section. As shown in FIG. 2, the conductive layer 52 covers the entire outer peripheral surface of the core material 51 from one end to the other end in the longitudinal direction of the core material 51.

The conductive layer 52 is made of a thin film (a two-layer plating film in this embodiment) and is formed by electrolessly plating the surface of the core material 51 using a catalyst such as Pd, and then electrolytically plating the electrolessly plated core material 51. As shown in FIG. 4A, the thickness T of the conductive layer 52 made of the electroless plating film and the electrolytic plating film is not particularly limited, but is preferably 10 μm or more. Examples of materials that constitute the conductive layer 52 include Cu, Ni, Sn, Ni-Sn, Cu-Ni-Sn, Ni-Au, and Au. The conductive layer 52 may also be formed by other means for forming a thin film (such as a sputtering method).

As shown in FIG. 2, a coil pattern 520 is formed on the conductive layer 52. The coil pattern 520 has a spiral (coil) shape and is formed from one end of the conductive layer 52 in the X-axis direction to the other end. The coil pattern 520 is formed by spirally patterning the plating layer (conductive layer) formed on the surface of the core material 51, thereby removing the plating layer in a spiral shape.

As shown in FIG. 3, one end of the coil pattern 520 is disposed at one end of the core material 51 in the X-axis direction, and the other end of the coil pattern 520 is disposed at the other end of the core material 51 in the X-axis direction. When the size of the coil device 10 is 0402 size, the spacing between each turn in the coil pattern 520 is preferably 3 to 11 μm, and more preferably 5 to 9 μm.

As shown in FIG. 2, the terminal portion 53 is formed on one end face and the other end face of the core material 51 in the X-axis direction. The terminal portion 53 formed on one end face of the core material 51 in the X-axis direction is provided at one end of the coil pattern 520 and is electrically connected to that end. The terminal portion 53 formed on the other end face of the core material 51 in the X-axis direction is provided at the other end of the coil pattern 520 and is electrically connected to that end. The terminal portion 53 covers the entirety of each end face, but may cover only a portion of each end face.

When the coil portion 40 is disposed inside the core portion 20, the inner surface (surface parallel to the Y-Z plane) of the first external terminal 31 is electrically connected to the terminal portion 53 formed on one end face of the core material 51 in the X-axis direction, and the inner surface (surface parallel to the Y-Z plane) of the second external terminal 32 is electrically connected to the terminal portion 53 formed on the other end face of the core material 51 in the X-axis direction. This makes it possible to electrically connect the coil pattern 52 to the first external terminal 31 and the second external terminal 32 via the terminal portion 53.

The terminal portion 53 is formed of an electroless plating film or an electrolytic plating film (conductive film) made of Cu, Ni, Sn, Ni-Sn, Cu-Ni-Sn, Ni-Au, Au, etc. The thickness of the terminal portion 53 is determined and set within a range that can sufficiently ensure electrical connection between each end of the coil pattern 520 and the external terminals 31, 32.

Next, a method for manufacturing the coil device 10 will be described with reference to FIG. 5. In manufacturing the coil device 10, first, a long core material 51A (hereinafter referred to as long core material 51A) is prepared. The long core material 51A is made of the same material as the core material 51 shown in FIG. 2, and has a shape that is sufficiently longer in the X-axis direction than the core material 51.

Next, electroless plating is applied to the surface of the long core material 51A using a catalyst such as Pd to form an electroless plating layer 521 made of Cu or the like. Next, electrolytic plating is applied to the surface of the electroless plating layer 521 to form an electrolytic plating layer 522 made of Cu or the like (plating process). As a result, a conductive layer 52 made of the electroless plating layer 521 and the electrolytic plating layer 522 is formed on the surface of the long core material 510A, and a long conductive thread 50A (hereinafter referred to as long conductive thread 50A) with the long core material 510A as the core material is formed.

Next, the surface of the long conductive thread 50A on which the conductive layer 52 is formed is patterned to form a coil pattern 520 (patterning process). In the patterning process, a portion of the conductive layer 52 is spirally removed by laser trimming to expose the long core material 51A (insulating fiber) below the conductive layer 52. As a result, a spiral groove (circumferential groove) is formed in the conductive layer 52, and the coil pattern 520 is formed in the portion other than the circumferential groove, i.e., the conductive layer 52 that remains untrimmed. In addition to laser trimming, patterning may be performed by photolithography (either positive or negative) using a resist, or by etching (physical or chemical etching), etc.

When forming the circumferential groove, laser trimming is performed continuously from one end of the long conductive thread 50A in the X-axis direction to the other end of the long conductive thread 50A in the X-axis direction. Laser trimming is performed using a laser irradiation device (not shown) by moving the long conductive thread 50A along the X-axis direction of the long conductive thread 50A while simultaneously rotating the long conductive thread 50A in the rotation direction around the axis O of the long conductive thread 50A. The depth of the circumferential groove is preferably 2 to 10 μm.

Next, the patterned long conductive thread 50A is cut at a predetermined cutting interval in the X-axis direction along the Y-Z plane to obtain a plurality of individual pieces of long conductive thread 50A (conductive thread 50) with coil patterns 520 formed on their surfaces (cutting process). The length of the conductive thread 50 (the above-mentioned cutting interval) may be appropriately determined according to the size of the coil device 10 to be manufactured.

Next, terminal portions 53 are formed on each end surface of the conductive thread 50 in the X-axis direction, and the terminal portions 53 are provided (connected) to each end of the coil pattern 520 formed on the surface of the conductive thread 50 to form the coil portion 40 (terminal portion forming process). The method of forming the terminal portions 53 is the same as the method of forming the conductive layer 52 described above, and is performed by applying electroless plating and electrolytic plating to each end surface of the conductive thread 50 in the X-axis direction. However, the method of forming the terminal portions 53 is not limited to this, and for example, a conductive adhesive or the like may be applied to each of the end surfaces, or the terminal portions 53 may be formed of a metal terminal or a lead frame.

Next, the conductive thread 50 (coil section 40) on which the terminal section 53 is formed is covered (sealed) with resin to form the core section 20 (resin sealing process). The resin used preferably has a lower dielectric constant than the insulating fiber constituting the long core material 51A. In the resin sealing process, the conductive thread 50 is placed inside a mold, and the core section 20 is formed by compression molding inside the mold. During compression molding, the cavity of the mold is filled with resin, and the entire structure is heated and compressed. At this time, compression molding is performed so that the terminal sections 53 formed on each end face of the coil section 40 in the X-axis direction are exposed to the outside. As a method for compression molding, a mold may be used, or hydraulic or water pressure may be used. Magnetic powder may be mixed inside the resin.

Next, the external terminals 51, 52 are mechanically and electrically connected to the terminal portions 53 exposed from each end face in the X-axis direction of the core portion 20 (external terminal connection process), to obtain the coil device 10 shown in FIG. 1. The external terminals 51, 52 are connected to the terminal portions 53 using a conductive connection member such as solder or a conductive adhesive. The coil device 10 obtained in this manner can be mounted on a circuit board with its underside as the mounting surface.

In the above-described manufacturing method, the timing of performing the cutting process may be changed as appropriate. For example, the cutting process may be performed on the long core material 51A before the plating process. Alternatively, the cutting process may be performed on the long core material 51A before the pattern processing process. In this case, pattern processing is performed on the conductive thread 50 (individual pieces of the long conductive thread 50A).

In the manufacturing method of the coil device 10 according to the present embodiment, as shown in FIG. 5, a process of forming a coil pattern 520 by patterning the surface of the long conductive thread 50A in which a conductive layer 52 is formed on the surface of an insulating fiber (straight core material 51A). Since the long conductive thread 50A is made based on insulating fibers, it is highly flexible and has durability (flex resistance) against repeated bending. Therefore, even if a load is applied to the long conductive thread 50A due to bending or bending during the formation stage of the coil pattern 520, damage such as breakage or cracking is unlikely to occur (high strength). Therefore, it is possible to prevent a decrease in yield caused by damage to the long conductive thread 50A, and for example, by dividing the long conductive thread 50A into individual pieces, it is possible to mass-produce individual pieces (conductive thread 50) of the long conductive thread 50A in which the coil pattern 520 is formed. Therefore, according to the manufacturing method of the coil device 10 according to the present embodiment, it is possible to mass-produce small coil devices 10 with high efficiency.

In addition, this embodiment further includes a process of cutting the patterned long conductive thread 50A to a predetermined length to form individual pieces of long conductive thread 50A (conductive thread 50). Therefore, it is possible to obtain multiple individual pieces of long conductive thread 50A from one long conductive thread 50A, and individual pieces of long conductive thread 50A on which coil pattern 520 is formed can be mass-produced with high efficiency.

In addition, in this embodiment, the conductive thread 50 is made of a single insulating fiber thread with a conductive layer 52 formed on its surface. This makes it easy to form the conductive layer 52 on the surface of the insulating fiber (core material 51), making it easy to form the coil pattern 520.

In addition, in this embodiment, the insulating fiber (core material 51) is made of synthetic resin, and aramid fiber is used as the synthetic resin. Aramid fiber has a relatively low dielectric constant and dielectric tangent (tan δ), and a relatively high heat resistance temperature. Therefore, by using a synthetic resin with such characteristics as the insulating fiber, it is possible to mass-produce small coil devices 10 that have good high-frequency characteristics and high heat resistance with high efficiency.

In addition, this embodiment further includes a process of coating the patterned conductive thread 50 with resin. Therefore, the conductive thread 50 is effectively protected by the resin, and external terminals 31, 32 for connecting the coil device 10 to an external circuit can be provided on the core portion 20 (resin-coated portion).

In addition, in this embodiment, the pattern processing is performed by laser trimming. This makes it possible to precisely pattern the surface of the conductive layer 52 formed on the surface of the conductive thread 50, and the coil pattern 520 can be formed with high precision on the surface of the conductive layer 52.

In addition, in this embodiment, the heat resistance temperature of the insulating fiber is 200°C or higher. Therefore, it is possible to manufacture a coil device 10 with high heat resistance that can withstand the solder reflow temperature.

The coil device 10 according to this embodiment has a core material 51 made of insulating fibers. Insulating fibers have excellent flexibility and bending resistance, and are less likely to be damaged. Furthermore, long insulating fibers can be diced to produce a large number of individual pieces of insulating fibers. Therefore, by using insulating fibers having the above characteristics as the core material 51, it is possible to prevent a decrease in yield due to damage to the core material 51 in the manufacturing process of the coil device 10, and it is also possible to produce a large number of small core materials 51. Therefore, according to the coil device 10 according to this embodiment, it is possible to realize a coil device 10 that is small and suitable for mass production.

The coil device 10 according to this embodiment has a conductive thread 50 in which a conductive layer 52 is formed on the surface of an insulating fiber (core material 51), and a coil pattern 520 made of the conductive layer 52. As described above, the conductive thread 50 has excellent flexibility and bending resistance, and is not easily damaged. Therefore, it is possible to prevent a decrease in yield caused by damage to the conductive thread 50. For example, by dividing the long conductive thread 50A into individual pieces, individual pieces (conductive thread 50) of the long conductive thread 50A in which the coil pattern 520 is formed can be mass-produced with high efficiency, and small coil devices 10 can be obtained in large quantities based on these individual pieces.

The coil device 10 according to this embodiment can be deformed into any shape by utilizing its flexibility. For example, depending on the application, the conductive thread 50 can be bent into various shapes such as a C-shape (U-shape) or a ring shape, and the coil device 10 having the conductive thread 50 can be placed on a substrate and connected to an external circuit. In this case, the core portion 20 can be made of a flexible material so that the core portion 20 can be freely deformed to follow the shape of the conductive thread 50 (coil portion 20) as described above.

The coil device according to the second embodiment shown in Fig. 4B has a similar configuration to the coil device 10 according to the first embodiment, and exerts the same effects and advantages, except for the following points: In Fig. 4B, the members common to the coil device 10 according to the first embodiment are given the same reference numerals, and some of the descriptions thereof will be omitted.

As shown in FIG. 4B, the coil device in this embodiment is provided with conductive thread 150 instead of the conductive thread 50 in the first embodiment. The conductive thread 150 is made of a bundle of (multiple) insulating fiber threads (core material 51) with a conductive layer formed on the surface. In other words, the conductive thread 150 is a bundle of threads in which multiple core materials 51 made of insulating fibers are gathered together and bonded into a bundle. In this embodiment, each core material 51 extends linearly and is not twisted.

The thickness of each core material 51 is thinner than the thickness of the core material 51 in the first embodiment, but may be changed as appropriate depending on the dimensions of the coil device. In the illustrated example, the conductive thread 150 is composed of 10 core materials 51, but the number of core materials 51 that compose the conductive thread 150 is not limited to this, and may be 2 to 9 or less, or 11 or more.

The conductive layer 52 is formed so as to surround the periphery of the bundled yarn. The conductive layer 52 is formed on the surface of the bundled yarn and does not penetrate into the interior of the bundled yarn.

Next, a method for manufacturing the coil device in this embodiment will be described with reference to Figures 7 to 11. In this embodiment, the coil device can be manufactured by the same manufacturing method as in the first embodiment, but below, a manufacturing method different from the manufacturing method shown in the first embodiment will be described. As will be described below, in this embodiment, the coil device is manufactured by injection molding.

First, as shown in FIG. 7, a lead frame 60 and a long conductive thread 50A (see FIG. 5(d)) that has been subjected to the pattern processing shown in the first embodiment are prepared. In this embodiment, the long conductive thread 50A is a bundle of core materials 41 as shown in FIG. 4B, but the detailed shape is omitted to prevent the drawing from becoming too complicated. The lead frame 60 is made of a conductive plate material such as a metal plate (e.g., a Sn-plated metal plate, etc.), and has a frame main body 61 and multiple frame openings 62 (four in the illustrated example) formed in the frame main body 61.

The frame main body 61 has a substantially rectangular shape, but the shape is not limited to the shape shown in the figure and may be changed as appropriate. Also, each frame opening 62 has a rectangular shape, but the shape is not limited to the shape shown in the figure and may be changed as appropriate, for example to a circular shape. Each of the four frame openings 62 is arranged at a predetermined interval in the X-axis direction and the Y-axis direction in the frame main body 61. As described later, each frame opening 62 is formed in the frame main body 61 so as to correspond to the arrangement position of each long conductive thread 50A. Note that the number of frame openings 62 is not limited to four, and may be changed as appropriate, such as 1 to 3 or 5 or more, depending on the number of long conductive threads 50A arranged in the frame main body 61, as described later.

Next, each of the multiple (four in the illustrated example) long conductive threads 50A is placed on the frame main body 61. More specifically, both ends in the X-axis direction of the long conductive thread 50A are placed on the periphery of the frame opening 62, and the long conductive thread 50A is placed above the frame opening 62 so as to straddle the frame opening 62 along the X-axis direction. Note that, instead of the long conductive thread 50A, individual pieces of the long conductive thread 50A (see Figures 5(e) and (f)) may be placed on the frame main body 61.

Next, as shown in FIG. 8, the lead frame 60 on which the long conductive thread 50A is arranged is placed on a mold 70. Here, the mold 70 has an upper mold 71 and a lower mold 72, which are configured to be combinable (connectable) in the vertical direction (Z-axis direction). The upper mold 71 has an upper recess 73 and an injection hole 75, and the lower mold 72 has a lower recess 74. Although detailed illustration is omitted, four upper recesses 73 are formed in the upper mold 71, and four lower recesses 74 are formed in the lower mold 72 to correspond to each of the four frame openings 62 shown in FIG. 7.

When placing the lead frame 60 with the long conductive thread 50A shown in FIG. 7 on the mold 70, the lead frame 60 is placed on the lower mold 72 as shown in FIG. 8. At this time, the frame opening 62 and the lower recess 74 are aligned so that they are connected to each other. Preferably, the long conductive thread 50A is placed above the lower recess 74, approximately in the center in the X-axis direction. The opening area of the frame opening 62 may be approximately equal to the opening area of the lower recess 74, or may be smaller than the opening area of the lower recess 74.

As shown in FIG. 9, when the upper mold 71 and the lower mold 72 are combined in the vertical direction, the upper recess 73 and the lower recess 74 are connected in the same direction, and a resin filling space (cavity) 76 is formed inside the mold 70. The resin filling space 76 can be filled with molding resin (exterior resin) 90 that constitutes the core part 20 shown in FIG. 1. The injection hole 75 is a hole for injecting the molding resin 90 into the resin filling space 76, and by using an injection machine 80, it is possible to inject the molding resin 90 into the resin filling space 76 through the injection hole 75. The injection hole 75 may be formed in the lower mold 72 instead of the upper mold 71.

Next, the upper mold 71 is combined with the lower mold 72 in the vertical direction. This forms a resin-filled space 76 inside the mold 70, and the long conductive thread 50A is placed inside the resin-filled space 76. The inside of the resin-filled space 76 is sealed from the outside of the resin-filled space 76. The lead frame 60 is fixed between the upper mold 71 and the lower mold 72, sandwiched between them in the vertical direction.

Next, the injection machine 80 is used to fill the resin filling space 76 with molding resin 90 through the injection hole 75. As the molding resin 90, any of the various resins that constitute the core portion 20 exemplified in the first embodiment can be used.

Here, as shown in FIG. 7, the Y-axis width of the frame opening 62 is sufficiently larger than the Y-axis width of the long conductive thread 50A, so that when the long conductive thread 50A is placed in the frame main body 61, the frame opening 62 is not completely blocked by the long conductive thread 50A. Therefore, as shown in FIG. 9, when the long conductive thread 50A is placed inside the resin filling space 76, the space (lower recess 74) located below the frame opening 62 and the space (upper recess 73) located above the frame opening 62 are in communication with each other through the frame opening 62 (more specifically, the portion where the long conductive thread 50A is not placed). Therefore, when the molding resin 90 is injected into the resin filling space 76 through the injection hole 75, the molding resin 90 flows through the frame opening 62 to the lower part of the resin filling space 76 located below the frame opening 62.

Next, when the inside of the resin filling space 76 is filled with the molding resin 90, the injection of the molding resin 90 is stopped. Next, the molding resin 90 filled inside the resin filling space 76 is hardened. For example, when a thermosetting resin is used as the molding resin 90, the molding resin 90 is hardened by heating. Also, when a thermoplastic resin is used as the molding resin 90, the molding resin 90 is hardened by cooling.

After the molding resin 90 is cured, the upper mold 71 and the lower mold 72 are separated. This results in a plurality of (four in the illustrated example) resin molded bodies 100, as shown in FIG. 10. The resin molded body 100 is formed by covering the long conductive thread 50A with the molding resin 90. The overall shape of the resin molded body 100 corresponds to the spatial shape of the resin filling space 76 shown in FIG. 9, and the long conductive thread 50A is embedded inside the resin molded body 100. Note that in FIG. 10, the resin molded body 100 appears to be formed only on the upper side of the lead frame 60, but in reality, it is formed so as to straddle the upper and lower sides of the lead frame 60.

Next, each resin molded body 100 is cut. More specifically, the resin molded body 100 is cut along cutting lines Ly ₁ and Ly _n extending along the Y-axis direction, and excess portions located at each end of the resin molded body 100 in the X-axis direction are removed. In addition, the resin molded body 100 is cut at predetermined intervals in the X-axis direction along cutting lines Ly ₂ , ..., Ly _n-1 extending along the Y-axis direction, and the resin molded body 100 is divided into a plurality of pieces (Ly _n-1 -Ly ₂ +1 pieces). At this time, the lead frame 60 is also cut together with the resin molded body 100.

As described above, when the long conductive thread 50A is placed in the frame main body 61 (see Figure 7), if individual pieces of the long conductive thread 50A are placed in the frame main body 61 instead of the long conductive thread 50A, it is sufficient to cut the resin molded body 100 along the cutting lines _Ly1 , _Lyn (removing the excess portions located at each end of the resin molded body 100 in the X-axis direction).

Next, as necessary, the resin molded body 100 is cut together with the lead frame 60 along cutting lines _Lx1 and _Lx2 extending along the X-axis direction, and excess portions located at each end of the resin molded body 100 in the Y-axis direction are removed. Through the above-described cutting process, individual pieces of the resin molded body 100 can be obtained in which the coil portion 40 (pieces of the long conductive thread 50A) are exposed from the end faces in the X-axis direction, as shown in Fig. 11. As necessary, the individual pieces of the resin molded body 100 may be deburred.

Then, external terminals 31, 32 (FIG. 5(h)) are connected to each end face in the X-axis direction of the individual pieces of the resin molded body 100. The external terminals 31, 32 may be directly connected to the conductive layers 52, 52 of the coil section 40 exposed from each end face in the X-axis direction of the individual pieces of the resin molded body 100. Alternatively, as in the first embodiment, terminal sections 53, 53 (see FIG. 5(g)) may be formed on each end face in the X-axis direction of the individual pieces of the resin molded body 100, and the external terminals 31, 32 may be connected to the terminal sections 53, 53.

In this manner, the coil device of this embodiment can be obtained. Note that the manufacturing method of the coil device of this embodiment can also be applied to the coil device 10 of the first embodiment, or the coil devices of the embodiments described below.

In this embodiment, the same effects as in the first embodiment can be obtained. In addition, the conductive thread 150 in this embodiment is composed of a bundle of core material 51 with a conductive layer 52 formed on the surface, so that it has excellent flexibility and bending resistance, and can effectively prevent a decrease in yield due to damage to the conductive thread 150.

The coil device according to the third embodiment shown in Fig. 4C has the same configuration as the coil device according to the second embodiment, and exerts the same effects, except for the following points: In Fig. 4C, the members common to the members in the coil device of the second embodiment are given the same reference numerals, and the description thereof will be partially omitted.

As shown in FIG. 4C, the coil device in this embodiment is provided with conductive thread 250 instead of conductive thread 150 in the second embodiment. Conductive thread 250 differs from conductive thread 150 in the second embodiment in that each of a plurality of core materials 51 is a twisted wire twisted in a spiral shape. In the illustrated example, conductive thread 250 is composed of two core materials 51, but the number of core materials 51 constituting conductive thread 250 is not limited to this and may be three or more.

In this embodiment, the same effect as in the second embodiment can be obtained. In addition, in this embodiment, by twisting each core material 51, the core materials 51 are entangled and tightened together, so that the core materials 51 are less likely to come loose even when pulled, and the strength of the conductive thread 250 can be increased.

The present invention is not limited to the above-described embodiment, and can be modified in various ways within the scope of the present invention.

In each of the above embodiments, as shown in FIG. 1, the external terminals 31, 32 are configured as metal terminals having a generally L-shape, but the shape of the external terminals 31, 32 is not particularly limited, and they may be configured as metal terminals having a flat plate shape. In addition, the external terminals 31, 32 may be configured as something other than a metal terminal (for example, an electrode film, etc.).

In each of the above embodiments, as shown in FIG. 6, both ends of the coil portion 20 may be pulled out to the outside of the core portion 20 along the end faces and part of the bottom surface of the core portion 20, and these pulled out parts may be used as terminal portions 53. In this case, external terminals 31, 32 may be connected to both ends of the coil portion 20 pulled out to the outside of the core portion 20. Alternatively, these pulled out parts may be used as external terminals.

In each of the above embodiments, the shape of the core portion 20 is not limited to the shape shown in FIG. 1, and may be, for example, a triangular prism, a pentagonal prism, another polygonal prism, or an approximately cylindrical shape. In addition, in the example shown in FIG. 1, the core portion 20 has a shape that extends straight in the X-axis direction, but it may also be a curved shape (for example, an approximately C-shape or an approximately ring shape) or a bent shape.

In each of the above embodiments, as shown in FIG. 2, the shape of the conductive thread 50 (or the core material 51) is cylindrical, but the shape of the conductive thread 50 (or the core material 51) is not limited to this and may be, for example, a triangular prism, a rectangular prism, a pentagonal prism, or other polygonal prism shape.

In each of the above embodiments, the spacing between each turn in the coil pattern 520 may be changed as appropriate depending on the required inductance value of the coil device 10, etc.

DESCRIPTION OF SYMBOLS 10... Coil device 20... Core portion 31... First external terminal 32... Second external terminal 40... Coil portion 50, 50A, 150, 250... Conductive thread 51... Core material 52... Conductive layer 520... Coil pattern 521... Electroless plating layer 522... Electrolytic plating layer 53... Terminal portion 60... Lead frame 61... Frame main body portion 62... Frame opening 70... Mold 71... Upper mold 72... Lower mold 73... Upper recess 74... Lower recess 75... Injection hole 76... Resin filling space 80... Injector 90... Molding resin 100... Resin molded body

Claims (14)

A step of forming a coil pattern by patterning an outer peripheral surface of the conductive yarn having a conductive layer formed on the surface of the insulating fiber;
A method for manufacturing a coil device, comprising the steps of: providing a terminal portion made of the conductive layer on an end surface of the conductive thread so as to be connected to an end of the coil pattern. The method for manufacturing a coil device according to claim 1, further comprising the step of cutting the conductive thread that has been subjected to the patterning process to a predetermined length to form individual pieces of the conductive thread. The method for manufacturing a coil device according to claim 1 or 2, wherein the conductive thread is made of a single insulating fiber thread having the conductive layer formed on its surface. The method for manufacturing a coil device according to claim 1 or 2, wherein the conductive thread is made of a bundle of insulating fiber threads on the surface of which the conductive layer is formed. The method for manufacturing a coil device according to any one of claims 1 to 4, wherein the insulating fibers are made of synthetic resin. The method for manufacturing a coil device according to any one of claims 1 to 5 further comprises a step of coating the conductive thread that has been subjected to the pattern processing with resin. The method for manufacturing a coil device according to any one of claims 1 to 6, in which the pattern processing is performed by laser trimming. The method for manufacturing a coil device according to any one of claims 1 to 7, wherein the heat resistance temperature of the insulating fiber is 200°C or higher. A conductive thread having a core material made of insulating fibers and a conductive layer formed on a surface of the core material;
and an external terminal electrically connected to the conductive yarn,
the conductive layer has a coil pattern formed on an outer circumferential surface of the core material and a terminal portion formed on an end surface of the core material,
The terminal portion is a coil device that electrically connects the coil pattern and the external terminal . The coil device according to claim 9 , wherein the conductive yarn is made of a single thread of the insulating fiber having the conductive layer formed on a surface thereof. The coil device according to claim 9 , wherein the conductive yarn is made of a bundle of the insulating fiber yarns having the conductive layer formed on a surface thereof. The coil device according to any one of claims 9 to 11 , wherein the insulating fibers are made of synthetic resin. The coil device according to any one of claims 9 to 12 , wherein the conductive thread on which the coil pattern is formed is coated with a resin. The coil device according to any one of claims 9 to 13 , wherein the insulating fiber has a heat resistance temperature of 200°C or higher.

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