SURFACE MOUNTED INDUCTOR AND MANUFACTURING METHOD THEREFOR

Abstract

A formed body incorporating a coil by using: a coil formed by winding a conductive wire, and a formed body incorporating the coil, the formed body being formed with a sealing material containing a resin and a magnetic material. The coil is formed by winding the conductive wire so that lead-out ends are positioned at an outer periphery of a wound portion. The formed body is formed so that surfaces of the coil are partially exposed on four side surfaces of the formed body which are parallel to a winding axis of the coil, and the area of a portion of the formed body outside the outer periphery of the wound portion is almost equal to or smaller than the area of a portion of the formed body inside an inner periphery of the wound portion of the coil.

Claims

1. A manufacturing method for a surface mounted inductor including a coil formed by winding a conductive wire, and a formed body incorporating the coil, the formed body being formed with a sealing material containing a resin and a magnetic material, the manufacturing method comprising the steps of: forming a coil by winding a conductive wire so that lead-out ends are positioned at an outer periphery of a wound portion; forming a formed body by placing the coil between a pair of plate-shaped tablets which are formed with the sealing material, and integrating the tablets by a compression molding method so that the coil is partially exposed on four side surfaces of the formed body which are parallel to a winding axis of the coil, and the area of a portion of the formed body outside the outer periphery of the wound portion of the coil is almost the same as or smaller than the area of a portion of the formed body inside an inner periphery of the wound portion of the coil; and forming external terminals connected to the lead-out ends of the coil on surfaces of the formed body.

2. The manufacturing method for a surface mounted inductor according to claim 1, comprising, in the step of forming the coil, forming a coil having a wound portion formed in an elliptical shape by winding a conductive wire shape so that both of its ends are positioned at an outer periphery, and lead-out ends led out from the outer periphery of the wound portion, wherein a size in a minor axis direction of the wound portion and a size in a width direction of the formed body are made the same, and wherein a size in a major axis direction of the wound portion is made to have a size obtained by subtracting a size of two conductive wires from a size in a length direction of the formed body or less, and, in the step of forming the formed body, forming a formed body so that surfaces in the minor axis direction of the wound portion of the coil are exposed on two side surfaces opposed in the width direction of the formed body, and surfaces of the lead-out ends of the coil are exposed on two side surfaces opposed in the length direction of the formed body so as to connect the lead-out ends of the coil to external terminals.

3. A manufacturing method for a surface mounted inductor including a coil formed by winding a conductive wire, and a formed body incorporating the coil, the formed body being formed with a sealing material containing a resin and a magnetic material, the manufacturing method comprising the steps of: forming a coil having a wound portion formed in an elliptical shape by winding a conductive wire so that both of its ends are positioned at an outer periphery, and lead-out ends led out from the outer periphery of the wound portion, wherein a size in a minor axis direction of the wound portion and a size in a width direction of the formed body are made the same, wherein a size in a major axis direction of the wound portion is made to have a size obtained by subtracting a size of two conductive wires from a size in a length direction of the formed body or less, forming a formed body, in a cavity of a molding die, by placing the coil on a plate-shaped tablet formed with the sealing material, filling the sealing material on the coil, and integrating the coil and the tablet by a compression molding method or a powder compacting method so that surfaces in the minor axis direction of the wound portion of the coil are exposed on two side surfaces opposed in the width direction of the formed body, surfaces of the lead-out ends of the coil are exposed on two side surfaces opposed in the length direction of the formed body, and the area of a portion of the formed body outside the outer periphery of the wound portion of the coil is almost the same as or smaller than the area of a portion of the formed body inside an inner periphery of the wound portion of the coil, and forming external terminals connected to the lead-out ends of the coil on surfaces of the formed body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a perspective view showing the inside of a formed body of an embodiment of a surface mounted inductor according to the present disclosure when it is seen in a see-through state.

[0025] FIG. 2 is a cross-sectional view showing the inside of the formed body of the embodiment of the surface mounted inductor according to the present disclosure when it is seen in a see-through state.

[0026] FIG. 3 is a perspective view showing the embodiment of the surface mounted inductor according to the present disclosure.

[0027] FIG. 4 is a perspective view showing the arrangement of a coil and a tablet of the embodiment of the surface mounted inductor according to the present disclosure.

[0028] FIG. 5 is a top view showing the arrangement of the coil in a molding die and the tablet of the embodiment of the surface mounted inductor according to the present disclosure.

[0029] FIG. 6 is a cross-sectional view explaining the step of placing the coil and the tablet in the molding die of an embodiment a manufacturing method for a surface mounted inductor according to the present disclosure.

[0030] FIG. 7 is a cross-sectional view explaining the forming step of a formed body of the embodiment of the manufacturing method for a surface mounted inductor according to the present disclosure.

[0031] FIG. 8 is a perspective view showing the inside of a conventional surface mounted inductor when it is seen in a see-through state.

[0032] FIG. 9 is a perspective view for explaining a tablet of the conventional surface mounted inductor.

[0033] FIG. 10 is a top view showing the arrangement of a coil and a tablet in a molding die of the conventional surface mounted inductor.

DETAILED DESCRIPTION

[0034] One or more embodiments of the present disclosure include a coil formed by winding a conductive wire, and a formed body incorporating the coil, the formed body being formed with a sealing material containing a resin and a magnetic material. The coil has a wound portion obtained by winding the conductive wire so that both of its ends are positioned at an outer periphery, and lead-out ends led out from the outer periphery of the wound portion. The formed body is formed so that surfaces of the coil are partially exposed on four side surfaces of the formed body which are parallel to a winding axis of the coil, and that the area of a portion of the formed body outside the outer periphery of the wound portion is almost equal to or smaller than the area of a portion of the formed body inside an inner periphery of the wound portion of the coil. Therefore, in one or more embodiments of the present disclosure, since the size of the outer shape of the coil can be maximized within the range of the size of the outer shape of the formed body, a dead space in the formed body can be reduced, and the diameter of the winding axis section of the coil or the cross-sectional area of the conductive wire can be increased.

[0035] In one or more embodiments of the present disclosure, first, a coil is formed by winding a conductive wire so that lead-out ends are positioned at an outer periphery of a wound portion of the coil. Next, the coil is placed between a pair of plate-shaped tablets which are formed with a sealing material and formed to have almost the same size as that of the outer periphery of the coil. They are integrated by the compression molding method to form a formed body so that the coil is partially exposed on four side surfaces of the formed body which are parallel to the winding axis of the coil, and that the area of a portion of the formed body outside the outer periphery of the wound portion of the coil is almost the same as or smaller than the area of a portion of the formed body inside an inner periphery of the wound portion of the coil. Lastly, external terminals connected to the lead-out ends of the coil on surfaces of the formed body are formed. Therefore, in the manufacturing method for a surface mounted inductor of the present disclosure, since the size of the outer shape of the coil can be maximized within the range of the size of the outer shape of the formed body, a dead space in the formed body can be reduced, and the diameter of the winding axis section of the coil or the cross-sectional area of the conductive wire can be increased.

[0036] The best mode for carrying out the present disclosure will hereinafter be described with reference to FIG. 1 through FIG. 7.

[0037] FIG. 1 is a perspective view showing the inside of a formed body of an embodiment of a surface mounted inductor according to the present disclosure when it is seen in a see-through state, and FIG. 2 is a cross-sectional view showing the inside of the formed body of the embodiment of the surface mounted inductor according to the present disclosure when it is seen in a see-through state.

[0038] In FIG. 1, and FIG. 2, the reference numeral 11 denotes a coil, and the reference numeral 17 denotes a formed body.

[0039] The coil 11 is an air core coil, the coil 11 includes a wound portion 11a obtained by spirally winding a conductive wire in two-tiers in an outside-to-outside manner so that both of its ends are positioned at an outer periphery, and lead-out ends 11b led out from the wound portion 11a. As the conductive wire, a rectangular wire that is rectangular in cross section is used. The wound portion 11a is formed in an elliptical shape. Further, the lead-out ends 11b are formed by being led out from the wound portion 11a so as to be opposite to each other across the wound portion 11a, and by bending each lead-out end 11b in a direction opposite to the direction from which it is led out.

[0040] A formed body 17 is formed with a sealing material containing a resin and a magnetic material so as to incorporate the coil 11. As the sealing material, using as the magnetic material iron-based metal magnetic powder, for example, and using as the resin an epoxy resin, for example, those obtained by mixing them are used. The formed body 17 is formed so that a size W1 in a width direction is almost equal to an outer peripheral size W2 in a minor axis direction of the wound portion 11a of the coil 11. Also, the formed body 17 is formed so that a size L1 in a length direction is almost equal to or a little larger than a size obtained by adding an outer peripheral size L2 in a major axis direction of the wound portion 11a of the coil 11, a thickness A of one lead-out end 11b, and a thickness A of the other lead-out end 11b. On side surfaces opposed in the width direction of the formed body 17, surfaces in the minor axis direction of the wound portion 11a of the coil 11 are partially exposed. On side surfaces opposed in the length direction of the formed body 17, surfaces of the lead-out ends 11b of the coil 11 are exposed. At this time, the formed body 17 is formed so that the total area of portions D1, D2, D3 and D4 outside the outer periphery of the wound portion 11a of the coil 11 is almost the same as or smaller than the area of a portion S1 inside an inner periphery of the wound portion 11a of the coil 11. As shown in FIG. 3, a pair of external terminals 18 are formed on surfaces of this formed body 17.

[0041] The lead-out ends 11b which are respectively exposed on the side surfaces opposed in the length direction of the formed body 17 are connected to the external terminals 18, so that the coil is connected between the pair of external terminals 18.

[0042] Such a surface mount inductor is manufactured as follows. First, a conductive wire which is rectangular in cross section and provided with insulation coating is spirally wound in two-tiers in an outside-to-outside manner so that both of its ends are positioned at an outer periphery thus forming a wound portion. Thereafter, both the ends of the conductive wire are led out from the outer periphery of the wound portion, and further subjected to bending to form lead-out ends, thus forming an air core coil.

[0043] As described below, in order to form a formed body incorporating an air core coil 11 having a wound portion 11a and lead-out ends 11b, plate-shaped tablets 12, 13, each having almost the same size as that of an outer periphery of the coil 11, are formed with a sealing material as shown in FIG. 4.

[0044] Next, as shown in FIG. 5, the air core coil having the wound portion 11a and the lead-out ends 11b, which is in a state of being mounted on the plate-shaped tablet 12, is housed in a cavity of a molding die formed of an upper die 14 having a sectional die 14a and a sectional die 14b, and a lower die (not shown).

[0045] Subsequently, the tablet 13 is housed in the cavity of the molding die, where the air core coil having the wound portion 11a and the lead-out ends 11b, and the plate-shaped tablet 12 are housed, so as to be positioned on the air core coil. Thereby, as shown in FIG. 6, in the cavity of the molding die formed of the upper die 14 having the sectional die 14a and the sectional die 14b, and the lower die 15, the air core coil having the wound portion 11a and the lead-out ends 11b is arranged between the pair of plate-shaped tablets 12 and 13, and in this state, a punch 16 is set in the cavity of the molding die.

[0046] Furthermore, as shown in FIG. 7, the pair of plate-shaped tablets and the air core coil are molded by the so-called compression molding method in which they are compressed with the molding die and the punch at 120-250 C., whereby a formed body 17 incorporating the air core coil 11 is formed. This formed body 17 is formed so that surfaces in the minor axis direction of the wound portion 11a of the coil 11 are partially exposed on side surfaces opposed in the width direction of the formed body 17, that surfaces of the lead-out ends 11b of the coil 11 are exposed on side surfaces opposed in the length direction of the formed body 17, and that, when the formed body is seen in a see-through state from a winding axis direction of the coil, the area of a portion of the formed body outside the outer periphery of the wound portion 11a of the coil 11 is almost equal to or smaller than the area of a portion of the formed body inside an inner periphery of the wound portion 11a of the coil 11.

[0047] Treatment for removing the insulation coating is performed, which is treatment for removing the insulation coating of the lead-out ends 11bs of the coil 11 exposed on the side surfaces opposed in the length direction of the formed body 17 thus obtained, and barrel polishing treatment of the formed body 17 thus obtained is performed. The treatment for removing the insulation coating and the barrel polishing treatment may also be performed at the same time.

[0048] Referring again to FIG. 3, an external terminal material containing a conductive material is coated on surfaces of this formed body 17, and cured to form external terminals 18 on the surfaces of the formed body 17. The external terminals 18 may be plated with a material selected from one or a plurality of Ni, Sn, Cu, Au, Pd and the like as necessary.

[0049] The above has described the embodiments of the surface mounted inductor and manufacturing method therefor of the present disclosure, however, the present disclosure is not limited to these embodiments. For example, as the sealing material, the iron-based magnetic powder was used for the filling material, and the epoxy resin was used for the resin. As the filling material, metal magnetic powders having other compositions, metal magnetic powder whose surface is coated with an insulator such as glass, surface-modified metal magnetic powder, ferrite powder, glass fiber and the like may also be used. As the resin, a thermoset resin such as a polyimide resin or a phenol resin, and a thermoplastic resin such as a polyethylene resin or a polyamide resin may also be used. Furthermore, the wound portion of the coil may also be formed in a circular shape. Still furthermore, the formed body formed by placing the coil on the plate-shaped tablet formed with the sealing material in the cavity of the molding die, filling the coil with a powdery sealing material, and integrating them by the compression molding method or the powder compacting method may also be formed so that the surfaces in the minor axis direction of the wound portion of the coil are partially exposed on the side surfaces opposed in the width direction of the formed body, that the surfaces of the lead-out portions of the coil are exposed on the side surfaces opposed in the length direction of the formed body, and that the area of the portion of the formed body outside the outer periphery of the wound portion of the coil is formed almost equal to or smaller than the area of the portion of the formed body inside the inner periphery of the wound portion of the coil.