Electronic components

Abstract

We provide highly implementable electronic components. [Solution] An electronic component having an outer covering material covering an element, wherein the surface of the outer covering material exposed on the mounting surface of the electronic component has a plurality of recesses.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electronic component in which an element such as a coil is covered with an exterior material, for example.

BACKGROUND ART

[0002] Conventionally, electronic components are known in which electronic elements such as coils and capacitors are arranged inside an exterior body formed of a resin material. For example, Patent Document 1 describes a method of resin-sealing a capacitor element using a molding die to mold it as a single electronic component.

[0003] Even for this type of so-called resin-molded electronic component, miniaturization and higher performance have been advancing in recent years. When an electronic component is miniaturized, the mechanical strength of the electronic component generally tends to decrease. In addition, miniaturization of electronic components makes mounting on a substrate or the like more difficult, and improvement of mountability such as maintaining / improving the adhesion strength to the substrate or the like and reliably preventing short circuits between terminals caused by solder or the like becomes important.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0004]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] An object of the present invention is to provide an electronic component with high mountability.

MEANS FOR SOLVING THE PROBLEMS

[0006] An electronic component according to the present invention is: An electronic component having an exterior material covering an element, A surface of the exterior material exposed on a mounting surface of the electronic component has a plurality of recesses.

[0007] The electronic component according to the present invention, having these characteristics, has multiple recesses on the surface of its outer casing. For example, when electrodes are arranged on the mounting surface, it is possible to prevent solder from flowing along the surface of the outer casing when mounting the electronic component onto a substrate or the like. As a result, the formation of so-called solder bridges, i.e., short circuits between electrodes, caused by solder during mounting can be appropriately prevented.

[0008] Furthermore, because the surface of the exterior material of the electronic component according to the present invention, which has these characteristics, has multiple recesses, when, for example, an adhesive or the like is applied to the mounting surface to mount the electronic component onto a substrate, or when a portion or the entirety of the substrate on which the electronic component is mounted is further sealed with a separate resin material, the adhesive or sealing resin can enter into the recesses, thereby improving adhesion and bonding. As a result, the electronic component is firmly mounted onto the substrate, or a portion or the entirety of the substrate containing the electronic component is reliably sealed with resin.

[0009] Thus, according to the present invention, it is possible to provide an electronic component that can be mounted on a substrate or the like while maintaining proper electrical connections, and that can be mounted on a substrate or the like in a mechanically or physically robust and reliable manner.

[0010] The mounting surface may have an electrode surface of the element, and the electrode surface may not have the recess.

[0011] The surfaces of the exterior material other than the surface exposed to the mounting surface do not need to have the recesses.

[0012] The aspect ratio obtained by dividing the length along the opening surface of the recess by the depth of the recess may be between 2.0 and 5.0.

[0013] The recess has a circular or elliptical opening surface, and the diameter of the opening surface may be 3 to 30 μm.

[0014] The depth of the recess may be 1.5 to 10 μm.

[0015] The average distance between the plurality of recesses may be 5.0 to 50 μm.

[0016] The ratio (area ratio) of the total area of the opening surfaces of the recesses to the surface area of the exterior material exposed on the mounting surface may be 30 to 40%.

[0017] The element may be a coil, and the coil may be covered by the exterior material. [BRIEF DESCRIPTION OF THE DRAWINGS]

[0018] [Figure 1A] FIG. 1A is a perspective transparent view showing a configuration of a coil component according to an embodiment of the present invention. [Figure 1B] FIG. 1B is an external perspective view of the coil component shown in FIG. 1A viewed from the mounting surface side. [Figure 1C] FIG. 1C is a transparent front view of the coil component shown in FIG. 1A. [Figure 2A] FIG. 2A is a bottom view of the coil component shown in FIG. 1A, and is a diagram for explaining the recesses. [Figure 2B] FIG. 2B is a partial cross-sectional view at the section II-II in FIG. 2A. [Figure 2C] FIG. 2C is a diagram for explaining the distance between the recesses shown in FIG. 2A. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a state where the coil component shown in FIG. 1A is mounted on a substrate or the like. [Figure 4] FIG. 4 is a flowchart showing an example of a method for manufacturing the coil component shown in FIG. 1A. [Figure 5A] FIG. 5A is a first diagram for explaining the method for manufacturing the coil component shown in FIG. 4. [Figure 5B] FIG. 5B is a second diagram for explaining the method for manufacturing the coil component shown in FIG. 4. [Figure 5C] FIG. 5C is a third diagram for explaining the method for manufacturing the coil component shown in FIG. 4. [Figure 5D] FIG. 5D is a fourth diagram for explaining the method for manufacturing the coil component shown in FIG. 4. [Figure 6] FIG. 6 is a perspective transparent view showing a configuration of a coil component according to another embodiment of the present invention. [Mode for Carrying Out the Invention]

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are examples for illustrating the present invention. Various constituent elements according to the embodiments of the present invention, such as numerical values, shapes, materials, and manufacturing processes, can be modified or altered within a range that causes no technical problems.

[0020] The shapes and the like shown in the drawings of the present invention do not necessarily match the actual shapes and the like. This is because the shapes and the like may be modified for illustrative purposes.

[0021] A coil component 1 according to an embodiment of the present invention will be described with reference to FIG. 1A to FIG. 2C. As shown in FIG. 1A, the coil component 1 is an electronic component in which a coil portion 20 as an electronic element is sealed and accommodated inside an exterior material 10. The coil component 1 includes the exterior material 10 and the coil portion 20, and as shown in FIG. 1C, the coil portion 20 includes a coil 21, a pair of lead portions 22a, 22b, and a pair of electrode terminals 23a, 23b.

[0022] The coil component 1 has a substantially rectangular parallelepiped shape (hexahedron) having a top surface 1a, a bottom surface 1b that is a mounting surface, and side surfaces 1c to 1f. The pair of electrode terminals 23a, 23b are exposed on the mounting surface 1b of the coil component 1. On the surfaces other than the mounting surface 1b where the electrode terminals 23a, 23b are exposed, the outer surface of the exterior material 10 directly forms the outer surface of the coil component 1. Therefore, the top surface 1a and the side surfaces 1c to 1f of the coil component 1 are the top surface 10a and the side surfaces 10c to 10f of the exterior material 10, respectively. The mounting surface 1b of the coil component 1 has the mounting surface 10b of the exterior material 10 and outer surfaces (electrode surfaces) 231a, 231b of the electrode terminals 23a, 23b.

[0023] In this embodiment, the direction perpendicular to the mounting surface 1b of the coil component 1 is defined as the Z-axis direction, the direction along which the pair of electrode terminals 23a and 23b are arranged among the two pairs of opposing edges forming the periphery of the mounting surface 1b is defined as the X-axis direction, and the direction perpendicular to the X-axis direction and the Z-axis direction is defined as the Y-axis direction, and the coil component 1 will be described accordingly.

[0024] The coil component 1 in this embodiment is a small electronic component whose maximum side length in the planar direction is, for example, 5 mm or less, 3 mm or less, or 0.5 mm or less, and whose height is, for example, 5 mm or less, 3 mm or less, or 0.5 mm or less.

[0025] As shown in Figures 1A and 1B, the exterior material 10 has a rectangular parallelepiped shape (hexahedron) and has a top surface 10a, a mounting surface (bottom surface) 10b located on the opposite side of the top surface 10a in the Z-axis direction, and sides 10c to 10f. Sides 10c and 10d are located on opposite sides of each other along the X-axis, and side surfaces 10e and 10f are located on opposite sides of each other along the Y-axis. In the present invention, the rectangular parallelepiped shape includes a rectangular parallelepiped with chamfered corners and edges, and a rectangular parallelepiped with rounded corners and edges.

[0026] In this embodiment, the exterior material 10 is made of a resin material that does not contain magnetic powder. By adopting this configuration, the dielectric constant of the exterior material 10 is reduced, making the coil component 1 suitable for high-frequency applications.

[0027] The material for the exterior material 10 includes, for example, at least one of a thermosetting resin and a thermoplastic resin. The thermosetting resin includes, for example, at least one selected from the group consisting of epoxy resin, polyimide resin, phenolic resin, and unsaturated polyester resin. The polyimide resin is, for example, bismaleimide resin. The plastic resin includes, for example, at least one selected from the group consisting of crystalline polystyrene, fluororesin, polyethylene, liquid crystal polymer, and polyphenylene sulfide (PPS). The fluororesin is, for example, polytetrafluoroethylene (PTFE) resin.

[0028] Furthermore, the exterior material 10 may be made of a filler-containing resin in which the above-mentioned resin contains fillers such as hollow glass or needle-shaped glass. As a modified example, as will be described later, the exterior material 10 may be made of a magnetic powder-containing resin containing magnetic powder.

[0029] The mounting surface 10b of the outer casing material 10 is formed as the main surface facing the component mounting surface (mounting surface of a substrate, etc.) on which the coil component 1 is mounted. The mounting surface 10b exposes the mounting electrode surfaces 231a and 231b, which are the outer surfaces of a pair of electrode terminals 23a and 23b. The pair of mounting electrode surfaces 231a and 231b are spaced apart in the X-axis direction on the mounting surface 10b, and the electrode terminals 23a and 23b are insulated from each other.

[0030] As shown in Figure 1B, a plurality of recesses 100 are formed on the mounting surface 10b of the outer casing material 10. The recesses 100 are formed only on the mounting surface 10b of the outer casing material 10 that covers the coil portion 20, and are not formed on the mounting electrode surfaces 231a and 231b of the electrode terminals 23a and 23b. Furthermore, the recesses 100 are not formed on surfaces other than the mounting surface 10b of the outer casing material 10, i.e., the top surface 10a and the sides 10c to 10f (the top surface 1a and sides 1c to 1f of the coil component 1).

[0031] As shown in Figure 2A, the recesses 100 are formed (arranged) randomly but substantially uniformly across the entire mounting surface 10b of the exterior material 10. The shape of the opening surface 101 of the recesses 100 along the mounting surface 10b of the exterior material 10 is circular (subtly circular) or elliptical, and as shown in Figure 2B, its diameter (minor or major axis) L is approximately 3 μm to 30 μm. The depth D of the recesses 100 is approximately 1.5 μm to 10 μm. By forming such recesses 100 on the mounting surface 10b of the exterior material 10, as will be described later, the formation of solder bridges when mounting the coil component 1 can be prevented and the adhesion strength can be improved.

[0032] The shape and size of the opening surface 101 of the recess 100, and the depth of the recess 100, are not limited to the shape, size, and depth described above. For example, the shape of the opening surface 101 may be a rectangle or a polygon, or it may be a shape enclosed by a mixture of curved and straight sections. In other words, the shape of the opening surface 101 of the recess 100 may be any shape. Similarly, the size and depth of the opening surface 101 of the recess 100 may also be any size and depth.

[0033] However, the shape and size of the opening surface 101 of the recess 100, and the depth of the recess 100, may be defined within a predetermined range. That is, the recess 100 as referred to in the present invention may be defined by the shape and size of the opening surface 101 of the recess 100, and the depth of the recess 100. Specifically, a recess in which the radius of the circle inscribed in the opening surface 101 is 3 μm to 30 μm, the maximum length of the opening surface 101 is 3 μm to 30 μm, and the depth is 1.5 μm to 10 μm may be defined as the recess 100 as referred to in the present invention. The radius or maximum length of the circle inscribed in the opening surface 101 that defines the recess 100 may be defined as 5 μm to 25 μm, or as 10 μm to 20 μm. Furthermore, the depth defining the recess 100 may have a lower limit of 2 μm or 5 μm, and an upper limit of 8 μm or 5 μm.

[0034] The cross-sectional shape of the recess 100 is a semi-elliptical shape obtained by cutting an ellipse along its major axis, as shown in Figure 2B, for example, but is not limited to this. It may also have a rectangular cross-sectional shape or a semi-circular cross-sectional shape.

[0035] The recess 100 has an aspect ratio L / D obtained by dividing the length L along the opening surface by the depth D of the recess, which is between 2.0 and 5.0. However, the aspect ratio may also be used as an indicator to define the recess 100 as referred to in the present invention. The lower limit of the aspect ratio may be 2.5 or 3, and the upper limit may be 4 or 3.

[0036] For multiple recesses 100, the average distance between adjacent recesses 100 on the mounting surface 1b of the coil component 1 is between 5.0 μm and 50 μm.

[0037] The "average distance" referred to here is the average value obtained by detecting pairs of adjacent recesses 100 for multiple recesses 100 recognized as "recesses" of the present invention based on the definition of the shape and size of the opening surface 101 of the recess 100 and the depth of the recess 100, and / or for multiple recesses 100 recognized as "recesses" of the present invention based on the definition of the "aspect ratio" described above, determining the length (distance) C between the centers (geometric center, centroid, etc.) of the opening surface 101 of the two recesses 100, as shown in Figure 2C, and averaging the distance C between those centers.

[0038] This process of calculating the average distance may be performed on the recesses 100 formed on the entire surface of the mounting surface 10b of the exterior material 10, or a partial area may be set on the mounting surface 10b of the exterior material 10, and the calculation may be performed on the recesses 100 in that partial area.

[0039] Furthermore, on the mounting surface 1b of the coil component 1, the ratio (area ratio) of the total surface area of ​​the openings of the multiple recesses 100 to the total surface area of ​​the mounting surface 10b of the outer casing material 10 is 30% to 40%. However, this area ratio may also be 20% to 50% or 10% to 60%.

[0040] Furthermore, the "ratio of the total area of ​​the opening surfaces (total area ratio)" referred to here is calculated by taking into account multiple recesses 100 recognized as "recesses" of the present invention based on the definition based on the shape and size of the opening surfaces 101 of the recesses 100 and the depth of the recesses 100 as described above, and / or taking into account multiple recesses 100 recognized as "recesses" of the present invention based on the definition based on the "aspect ratio" as described above, and determining the ratio between the total of the opening surfaces 101 of the recesses 100 formed thereon and the area of ​​that region (the entire mounting surface 10b or a partial region of the mounting surface 10b).

[0041] By forming such recesses 100 on the mounting surface 10b of the exterior material 10, for example, when mounting the coil component 1 to the substrate 510 using solder 520, as shown in Figure 3, if there is a possibility that the solder 520 used to electrically connect the electrode terminals 23a, 23b of the coil component 1 to the conductive pattern 511 of the substrate 510 may flow along the mounting surface 10b of the exterior material 10, the solder 520 that has started to flow will enter and be stored in the recesses 100 on the mounting surface 10b of the exterior material 10, reducing the possibility that it will flow along the mounting surface 10b of the exterior material 10 to the electrode terminals 23a, 23b on the opposite side. As a result, the formation of so-called solder bridges by solder during mounting is prevented, and short circuits between the pair of mounting electrode surfaces 231a, 231b of the coil component 1 can be appropriately prevented.

[0042] Furthermore, by forming the recess 100 on the mounting surface 10b of the exterior material 10, for example, when fixing (mounting) the coil component 1 to the substrate 510 using adhesive 530, as shown in Figure 3, or when sealing a part or the entire substrate containing the coil component with a separate resin material (not shown), the adhesive 530 or sealing resin can enter the recess 100, improving adhesion and bonding. As a result, the coil component 1 is firmly mounted to the substrate 510. Alternatively, a part or the entire substrate containing the coil component 1 is reliably sealed with resin.

[0043] The coil section 20 has a coil 21 formed by winding a wire 200 as a conductor into a coil shape. In this embodiment, the coil 21 is housed in the outer material 10 in a vertical orientation where the winding axis is parallel to the mounting surface 1b of the coil component 1. The coil 21 in this embodiment is a coil in which the wire 200 is wound in a general normal width, but the winding method of the wire is not limited to this. For example, it may be a coil in which the wire is α-wound, or a coil in which the wire is flat-wound or edge-wound.

[0044] The wire 200 is composed of a conductor portion mainly containing a low-resistance metal such as copper, and an insulating coating covering the outer circumference of the conductor portion. The conductor portion is made of pure copper such as oxygen-free copper or tough pitch copper, copper-containing alloys such as phosphor bronze, brass, red copper, beryllium copper, or silver-copper alloy, or copper-clad steel wire. The insulating coating is not particularly limited as long as it has electrical insulating properties. Examples include epoxy resin, acrylic resin, polyurethane, polyimide, polyamide-imide, polyester-imide, nylon, polyester, polyvinyl formal, or a synthetic resin obtained by mixing at least two of the above resins.

[0045] Furthermore, in this embodiment, the wire 200 constituting the coil 21 is a round wire, and the cross-sectional shape of the conductor portion is circular. However, it is not limited to a round wire; a wire with a rectangular cross-section or a flat wire may also be used.

[0046] Furthermore, in this embodiment, the shape of the coil 21 in a plane perpendicular to the winding axis is a rectangle (square shape) with its corners gently curved in an arc. However, the shape of the coil 21 as viewed from the winding axis direction is not limited to this, and may be an ellipse, oblong, or perfect circle.

[0047] A pair of electrode terminals 23a, 23b are formed at both ends of the wire 200 constituting the coil 21 via a pair of lead-out portions 22a, 22b. Each electrode terminal 23a, 23b has a mounting electrode surface 231a, 231b that is exposed to the outside of the coil component 1 from the mounting surface 10b of the outer casing material 10.

[0048] The electrode terminals 23a and 23b are formed by processing the portions of the wire 200 that make up the coil 21, specifically the portions drawn out from the coil 21 at both ends. As is clear from Figures 1A and 1C, the ends of the wire 200 that make up the coil 21, i.e., the beginning and end portions of the wire 200, are positioned close to the mounting surface 1b in the Z-axis direction. The electrode terminals 23a and 23b are formed by processing the portions of the wire 200 that are further towards the ends, continuous with these beginning and end portions.

[0049] As shown in Figure 1A, the electrode terminals 23a and 23b are thin, plate-like members with a rectangular planar shape and low thickness. Each electrode terminal 23a and 23b is formed by crushing the wire 200. Therefore, in a cross-section perpendicular to the extending direction of the wire 200, the thickness of the electrode terminals 23a and 23b is smaller (thinner) than the outer diameter of the conductor portion of the wire 200 forming the coil 21 (if the cross-sectional shape of the conductor portion is not circular, this is the minimum value of the conductor portion, also called the "wire thickness"), and the width of the electrode terminals 23a and 23b is larger (wider) than the outer diameter of the conductor portion of the wire 200 forming the coil 21 (if the cross-sectional shape of the conductor portion is not circular, this is the maximum value of the conductor portion, also called the "wire width").

[0050] As shown in Figure 1C, the lead-out sections 22a and 22b are drawn out from the bottom surface of the coil 20 toward the mounting surface 1b. With this configuration, the lead-out sections 22a and 22b are positioned inward from the area occupied by the coil 21 on the mounting surface (XY plane), making it possible to reduce the size of the coil component 1 in the horizontal direction (in the plane parallel to the mounting surface).

[0051] As shown in Figure 2A, the electrode terminals 23a and 23b are positioned approximately opposite each other on both sides of the main surface 101b in the longitudinal direction (X-axis direction). However, the arrangement of the terminal bodies 511a and 511b on the plane parallel to the mounting surface (XY plane) is not limited to this, and any arrangement is acceptable as long as insulation between the two terminal bodies 511a and 511b is ensured within the region where the coil portion 201 is located.

[0052] The electrode terminals 23a and 23b have mounting electrode surfaces 231a and 231b formed along the mounting surface 10b of the outer casing material 10 so as to be exposed to the outside of the coil component 1, and terminal inner surfaces 232a and 232b on the opposite side of the mounting electrode surfaces 231a and 231b, which face the inside of the coil component 1 and are in close contact with the outer casing material 10. As described above, the electrode terminals 23a and 23b are formed by processing the wire 200, but at the locations of the electrode terminals 23a and 23b, the insulating coating present on the outer circumference of the wire 200 is removed, and the conductor portion of the wire 200 is exposed.

[0053] In this embodiment, the electrode terminals 23a and 23b are formed to protrude slightly from the mounting surface 10b of the exterior material 10. However, the electrode terminals 23a and 23b may also be formed flush with the mounting surface 10b of the exterior material 10 (as flat surfaces forming the same plane), or they may be formed as surfaces recessed from the mounting surface 10b of the exterior material 10.

[0054] Furthermore, a plating film may be formed on the mounting electrode surfaces 231a and 231b of the electrode terminals 23a and 23b exposed on the mounting surface 1b of the coil component 1. The plating film can be formed in film form by methods such as plating or sputtering using a metal such as Sn, Au, Cu, Ni, Pt, Ag, or Pd, or an alloy containing at least one of these metal elements. The thickness of the plating film is, for example, 50 μm or less.

[0055] By forming a plating film on the mounting electrode surfaces 231a and 231b, the flatness of the mounting electrode surfaces 231a and 231b is improved, and the wettability of the solder used to mount the coil component 1 to a substrate or the like is enhanced, enabling reliable electrical connection via the electrode terminals 23a and 23b.

[0056] Next, the manufacturing method of the coil component 1 will be explained, focusing on the process of sealing the coil portion 20 in the outer material 10, with reference to Figures 4 to 5D.

[0057] In the manufacturing of the coil component 1, first, the coil section 20 is created (step S1). The wire 200 is wound using a winding device (not shown) to form a coil (air-core coil) 21. Both ends of the wound wire 200 are extended inward (inward in the X-axis direction) by a predetermined length along the lower part 201a of the coil 21 (lower Z-axis direction), bent at approximately a right angle outward (downward Z-axis direction), and cut to a predetermined length. Next, the extended portions continuous with the coil 21 are secured as lead-out sections 22a and 22b. The ends are then crushed to form a pair of thin, flattened sections. The excess portions are cut off and bent to form a pair of electrode terminals 23a and 23b.

[0058] The coil portion 20 formed in this manner is placed on an adhesive sheet 400 to temporarily determine its position, as shown in Figure 5A (step S2). The adhesive sheet 400 is placed, for example, on a lower mold (not shown), and the coil portion 20 is pressed against the adhesive sheet 400 from the positive Z-axis side with constant pressure via a coil portion 20 holding device (not shown). As a result, the coil portion 20 is firmly adhered to the adhesive sheet 400 on the lower mold. This allows the position of the coil portion 20 on the lower mold to be fixed.

[0059] The adhesive sheet 400 may be any thin plate-shaped or sheet-shaped adhesive sheet having a certain adhesive strength and elasticity, and it is even better if it is an adhesive sheet with adjustable adhesive strength, but it is not limited to this. In this embodiment, an adhesive sheet is used in which the adhesive strength weakens when irradiated with ultraviolet (UV) light, in other words, an adhesive sheet in which the adhesive strength can be adjusted according to the amount of ultraviolet (UV) light irradiated. The adhesive sheet 400 may be a sheet in which bubbles are generated when irradiated with ultraviolet (UV) light, thereby changing the properties of the adhesive surface and changing the adhesive strength.

[0060] After the coil portion 20 is placed on the adhesive sheet 400, ultraviolet light (UV) is irradiated onto the adhesive sheet 400 from above and below (from both sides in the Z-axis direction) to adjust the adhesive strength and form protrusions 401 on the surface of the adhesive sheet 400 (step S3).

[0061] When ultraviolet (UV) light is irradiated onto the adhesive sheet 400 to which the coil portion 20 is attached from above and below (from both sides in the Z-axis direction), bubbles are generated from the adhesive sheet 400 in areas other than where the electrode terminals 23a and 23b are in close contact, and the adhesive strength of the adhesive sheet 400 weakens. This makes it easier to peel the coil component 1 from the adhesive sheet 400, in other words, to remove it from the mold, in subsequent processes. In addition, as the generated bubbles are discharged into the environment, or as some of the bubbles are blocked on the surface of the adhesive sheet 400, a protrusion is formed on the surface of the adhesive sheet 400 (the side on which the coil portion 20 is placed).

[0062] On the other hand, with respect to the adhesive sheet 400 in the area where the electrode terminals 23a and 23b are in close contact, ultraviolet (UV) light from above is blocked by the electrode terminals 23a and 23b, and the adhesive sheet 400 is pressed down by the electrode terminals 23a and 23b, so no air bubbles are generated in the adhesive sheet 400 and the adhesive strength is maintained to a firm state.

[0063] By irradiating the adhesive sheet 400 with ultraviolet (UV) light, the adhesive strength is adjusted and protrusions 401 are formed on the adhesive sheet 400 in areas other than the electrode terminals 23a and 23b. The protrusions are formed randomly and almost uniformly across the entire surface of the area of ​​the adhesive sheet 400 irradiated with ultraviolet (UV) light, except for the positions where the electrode terminals 23a and 23b are pressed.

[0064] Next, the coil section 20 is sealed (encapsulated) with the outer material 10 (step S4). That is, as shown in Figure 5B, the coil section 20 placed on the adhesive sheet 400 is arranged in a mold (not shown), and the outer material is injected into the mold, pressed, and hardened. As a result, as shown in Figure 5C, a coil component 1 is formed on a lower mold (not shown) and adhesive sheet 400, with the coil section 20 sealed (covered) by the outer material 10. If multiple coil sections 20 are sealed together, they are then separated into individual pieces. This separation may be performed immediately after the outer sealing step, or after a subsequent demolding (sheet peeling) step or plating step.

[0065] After the coil section 20 is sealed with the outer material 10 and the coil component 1 is formed, the next step is to separate the coil component 1 from the mold and the adhesive sheet 400 (step S5). As a result, the coil component 1 shown in Figure 5D is obtained. In the ultraviolet irradiation step (S3) described above, the adhesive force of the surface of the adhesive sheet 400 (the surface on the coil section 20 side) is weakened except for the electrode terminals 23a and 23b, that is, the adhesive force is adjusted, so the release of the coil component 1 and the peeling off of the adhesive sheet 400 can be performed appropriately without applying excessive mechanical load to the coil component 1.

[0066] As shown in Figure 5D, the coil component 1 obtained in this way has recesses 100 formed on the mounting surface 10b of the exterior material 10, where the protrusions 401 of the adhesive sheet 400 were previously formed. The recesses 100 are formed randomly but substantially uniformly across the entire mounting surface 10b of the exterior material 10, similar to the protrusions 401 of the adhesive sheet 400.

[0067] The coil component 1 is then completed by performing processes on the component consisting of the exterior material 10 and the coil section 20, as needed, such as polishing to remove the insulating coating or resin from the mounting electrode surfaces 231a and 231b of the wire 200, or by forming a plating film on the electrode terminals 23a and 23b. The coil component 1 can be manufactured by this method.

[0068] Variation The present invention is not limited to the embodiments or modifications described above, and various other modifications are possible.

[0069] For example, the electrode terminals 23a and 23b of the coil component 1 described above were formed by crushing the ends of the round wires that form the coil 21, and were exposed on the mounting surface 1b of the coil component 1 in the form of mounted electrode surfaces 231a and 231b. However, the form of the electrode terminals is not limited to this, and for example, as shown in Figure 6, they may be formed by a pair of L-shaped terminals 33a and 33b as separate members from the conductors that constitute the coil portion 20.

[0070] The coil component 2 shown in Figure 6 is identical to the coil component 1 described above, except that the electrode terminals 23a and 23b are replaced with L-shaped terminals 33a and 33b. All other configurations, functions, and effects are the same as those of coil component 1. The pair of L-shaped terminals 33a and 33b of coil component 2 are thin, plate-shaped metal members (conductors) and each has a mounting surface portion 331a and 331b and a side portion 332a and 332b, respectively. The mounting surface portions 331a and 331b and the side portions 332a and 332b are bent at approximately right angles. The mounting surface portions 331a and 331b are mounted on the mounting surface 2b of coil component 2, and the side portions 332a and 332b are mounted on the side portion 2d of coil component 2. The mounting surface portions 331a and 331b are electrically connected to the lead portions 22a and 22b of the coil portion 20, respectively, although this is not shown in the figure.

[0071] In a coil component 2 with this configuration, solder fillets can be formed on the side portions 332a and 332b located on the side surface 2d of the coil component 2, making the mounting of the coil component 2 to a substrate and electrical connection even more reliable. Furthermore, the process of forming electrode terminals 23a and 23b by flattening a round wire conductor is eliminated, and electrode terminals 33a and 33b can be formed by attaching an L-shaped metal member of a separate component, thus simplifying the manufacturing of the coil component 2. The present invention may be implemented in this form.

[0072] Furthermore, although the exterior material 10 in the above embodiment is made of a resin material that does not contain magnetic material, it may also be made of a magnetic powder-containing resin that contains magnetic powder. The magnetic powder is not particularly limited, but may be metallic magnetic particles. Examples include pure iron, Fe-Ni alloys, Fe-Si alloys, Fe-Co alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, amorphous metals, Fe-containing nanocrystalline alloys, other soft magnetic alloys, or combinations thereof. The magnetic particles may also be ferrite particles. Examples of ferrite materials include Ni-Zn ferrite and Mn-Zn ferrite. The magnetic powder may also have auxiliary components added as appropriate. In addition, the metallic magnetic particles contained in the exterior material 10 may be insulated from each other.

[0073] Furthermore, the electronic components are not limited to coil components such as inductors having an outer casing that houses the coil, but may also include coil components in which wires are wound around a powdered magnetic core, reactors, transformers, contactless power supply devices, and the like.

[0074] Examples Seventy coil components 1 according to this embodiment were manufactured, and the shape of the recess 100 was detected. The mechanical strength of the coil component 1 as a single unit, the adhesion strength when mounted on a substrate, and the possibility of solder bridging when mounted on a substrate were also evaluated.

[0075] Of these, the mechanical strength of each individual coil component was evaluated using a multi-functional bond tester.

[0076] Furthermore, the adhesion strength to the substrate was evaluated by the strength of the peel-off from the substrate, as shown in Table 1.

[0077] [Table 1]

[0078] Furthermore, the occurrence of solder bridges when mounted on a circuit board, etc., was evaluated based on whether solder bridges occurred under a predetermined mounting environment (mounting temperature), as shown in Table 2.

[0079] [Table 2]

[0080] Furthermore, for comparison, a coil component without any recess 100 was manufactured and evaluated similarly as a comparative example.

[0081] The evaluation results are shown in Tables 3 and 4.

[0082] [Table 3]

[0083] [Table 4]

[0084] As is clear from Tables 3 and 4, the mechanical strength of a coil component as a whole is related to the relationship between the length of the opening surface 101 of the recess 100 and the depth of the recess 100, that is, the aspect ratio related to the shape of the recess 100. If the aspect ratio is 2 or greater, the same strength as a coil component without any recess 100 can be maintained. In other words, from one perspective, it can be seen that if the recess 100 is relatively shallow, it does not affect the mechanical strength of the coil component as a whole.

[0085] Furthermore, as is clear from Tables 3 and 4, the adhesion strength when mounted on a substrate is improved in all embodiments compared to the comparative example where the recess 100 is not formed. Also, from one perspective, the adhesion strength improves as the aspect ratio of the recess 100 increases; for example, when the aspect ratio is 2 or greater, the adhesion strength consistently achieves a high evaluation value (3 or greater).

[0086] Furthermore, as is clear from Tables 3 and 4, the likelihood of solder bridging occurring when mounted on a substrate is reduced in all embodiments compared to the comparative example where the recess 100 is not formed. Also, from one perspective, the larger the aspect ratio of the recess 100, the lower the likelihood of solder bridging. For example, an aspect ratio of 2 or higher results in a high evaluation value (3 or higher) regarding the likelihood of solder bridging.

[0087] Furthermore, regarding the distance between recesses 100 and the area ratio of recesses 100, under the condition that recesses 100 with the same aspect ratio are formed, a tendency is observed for the mechanical strength of the coil component 1 alone, the adhesion strength when mounted on a substrate, and the likelihood of solder bridging when mounted on a substrate, to improve as the distance between recesses 100 decreases and the area ratio of recesses 100 increases. This tendency means that, in principle, the more recesses 100 there are on the mounting surface 10b of the exterior material 10, the better each evaluation becomes, thus confirming the effect of forming recesses 100.

[0088] However, as seen in Examples 67-70, when the distance between recesses 100 is extremely narrow (1 μm), and / or as a result the area ratio of recesses 100 is significantly high (50%), the mechanical strength of the coil component 1 as a whole decreases. This suggests that there are too many recesses 100, which reduces the strength of the coil component 1 (especially the strength of the exterior material 10). Therefore, it is desirable that the parameters such as the shape and arrangement of the recesses 100 described in this embodiment be appropriately selected within a range that does not lead to such a decrease in the strength of the coil component (especially the strength of the exterior material). [Explanation of symbols]

[0089] 1, 2… Coil parts 1a...Top surface, 1b...Mounting surface (bottom surface), 1c~1f...Sides 10… Exterior materials 10a...Top surface, 10b...Mounting surface (bottom surface), 10c~10f...Sides 100…recess 101…Opening surface 20... Coil section (electronic component) 200... wire 21…Coil (air-core coil) 22a, 22b...Drawer part 23a, 23b…electrode terminal 231a, 231b... Mounted electrode surface (electrode surface), 232a, 232b... Terminal inner surface 33a,33b…L-shaped terminal 331a, 331b...Mounting surface part 332a, 332b...side part 400... Adhesive sheet 510... Circuit board 511... Conductive pattern 520... solder 530…Adhesive

Claims

1. An electronic component having an outer covering material that covers the element, An electronic component in which the surface of the exterior material exposed on the mounting surface of the electronic component has a plurality of recesses.

2. The electronic component according to claim 1, wherein the mounting surface has an electrode surface of the element, and the electrode surface does not have the recess.

3. The electronic component according to claim 1, wherein the surface of the exterior material other than the surface exposed on the mounting surface does not have the recess.

4. The electronic component according to claim 1, wherein the aspect ratio obtained by dividing the length along the opening surface of the recess by the depth of the recess is 2.0 to 5.

0.

5. The electronic component according to claim 1, wherein the recess has a circular or elliptical opening surface, and the diameter of the opening surface is 3 to 30 μm.

6. The electronic component according to claim 1, wherein the depth of the recess is 1.5 to 10 μm.

7. The electronic component according to claim 1, wherein the average distance between the plurality of recesses is 5.0 to 50 μm.

8. The electronic component according to claim 1, wherein the ratio (area ratio) of the total area of ​​the opening surface of the recess to the surface area of ​​the exterior material exposed on the mounting surface is 30 to 40%.

9. The electronic component according to any one of claims 1 to 8, wherein the element is a coil, and the coil is covered by the exterior material.

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