Inductor devices – With outer casing or housing – Potted type
Patent
1997-04-03
1998-06-09
Kozma, Thomas J.
Inductor devices
With outer casing or housing
Potted type
333185, 336192, 336200, 336223, 361811, 361821, H01F 2729, H01F 2730
Patent
active
057641269
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a chip coil for use in the electronic appliance, communication apparatus, etc.
BACKGROUND ART
Shown in FIG. 6 is a perspective view of a conventional chip coil having spiral groove. Where, numeral 11 denotes a main body of square pillar shape around which a conductive member is provided on an insulating surface. Numeral 12 is a coil formed by spirally grooving the conductive surface layer of main body 11, 14 an insulation resin coated over the surface of coil 12, and 15 terminals of coil 12.
In a chip coil having a constitution as shown in the above FIG. 6, the surfaces of terminals 15 and the surface of the insulation resin 14 do not have complete flatness because the thickness of insulation resin 14 covering the main body 11 for an area between the terminals 15 is greater than the thickness of the terminals 15 located at both ends of main body 11. As a result, when a chip coil is mounted on a printed circuit board or the like the flatness between the surface of printed circuit board and the mounting surface of the chip coil is not secured, inviting a poor solderability between the terminal 15 and the printed circuit board or the like; which was a cause of mounting defects. What is shown in FIG. 7 is a chip coil proposed to solve the above drawbacks. The chip coil of FIG. 7 is provided with recesses 16 in the front, rear, top and bottom faces of the circumferential surface of main body 11 in an area between the terminals 15. With the above constitution, even in a case where insulation resin 14 is provided to cover the circumferential surface of main body 11 for an area between terminals 15, the insulation resin 14 is housed within recesses 16, and the flatness of the surfaces of terminals 15 and that of the surface of insulation resin 14 is improved to be better than that of a chip coil of FIG. 6, as a result the occurrence of mounting defects diminishes.
In the above constitution, however, as the main body 11 is provided with recesses 16 in the front, rear, top and bottom faces, it is not easy to take the main body 11 out of mould when manufacturing the main body through a moulding process; which is an adverse factor against the productivity. Furthermore, the recesses 16 provided in the front, rear, top and bottom faces of main body 11 reduce the cross sectional area of main body 11; accordingly the inductance which is subject to the cross sectional area of main body 11 also becomes smaller.
DISCLOSURE OF THE INVENTION
The present invention is intended to solve the above described problems, and presents a chip coil with which the mounting defects are reduced, a high productivity is preserved, at the same time the decrement in inductance is minimized.
In order to implement the above objective, a chip coil according to the present invention comprises a main body of an insulation material having a shape of square pillar, terminals provided at both ends of the main body, a coil connected with the terminals and disposed around the circumferential surface of the main body in an area between the terminals, and an insulation resin covering the coil; wherein the coil is formed by grooving off the insulation layer covering the surface of the main body, recesses are provided only at the top and bottom faces of the circumferential surface of the main body, and at the bottom surface of the main body the insulation resin is provided within the recess.
In the above described constitution, as the insulation resin is disposed within the bottom recess of the main body, an excellent flatness is secured at the bottom surface of the main body, rendering it difficult to cause mounting defects.
Furthermore, as there is no recess in the front and the rear of the main body it is easy to take the main body out of mould, which provides an improved productivity, and limits the decrease of cross sectional area of the main body, hence the decrease of inductance.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1(a) is a perspective view showing a chip coil, before coating of insulation
Kanetaka Toyonori
Taoka Mikio
Yoshizawa Toshihiro
Kozma Thomas J.
Matsushita Electric - Industrial Co., Ltd.
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