JPH02224307A - Inductance element - Google Patents

Abstract

PURPOSE:To obtain an inductance element having lesser disconnection of winding when thermal stress is generated and also having high mechanical strength by a method wherein a coating material, consisting of flexible resin material is provided on the surface of the winding part of a core, and an encapsulation, consisting of resin material having high mechanical strength, is provided on the surface of the coating material. CONSTITUTION:On a chip coil 1, a winding W is wound around the body part 2a of a core 2 made of ferrite material and the like, a covering material 3 consisting of a flexible resin material is formed on the body part 2, and the winding W is coated with the covering material 3. An encapsulation 4 made of resin material having high mechanical strength is formed on the surface of the coating material 3. As above- mentioned, the coating material 3 functions as a baffer material, the mechanical stress applied from outside and the stress of expansion and contraction of the encapsulation 4 by the heat cycle are hardly affected directly to the winding W. The mechanical strength of the chip coil 1 itself is enhanced by the encapsulation 4, and also the outside board 4 has the protective function such as prevention of fluidization of the coating material 3 by the thermal shock generating when a soldering work is conducted. As a result, the disconnection of winding can be prevented, and the handling of material when an element is mounted can also be made easier.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to inductance elements such as chip coils,
Related to LC filters, etc.

Prior Art and Problems Conventionally, a chip fill 11 shown in FIG. 2 has been known as this type of inductance element. Tepcoil 11
A winding W is wound around the body 12a of the core 12.

A resin body 13 is formed on the body 12a of this core 12 and covers the winding W. This resin body 13 is made of a flexible resin material or a resin material with high mechanical strength.

In the case where the resin body 13 is a flexible resin material, the resin body 13 acts as a buffer material, so that the resin body 1 which is generated due to external mechanical stress and heat cycle.
The stress of expansion/contraction in step 3 is less likely to be applied directly to the winding W.

Therefore, it has the advantage that the occurrence of disconnection of the winding W is small, but the mechanical strength of the chip coil 11 itself is relatively low, and furthermore, the resin body 13 flows due to thermal shock when soldering to a printed circuit board. There is a problem.

On the other hand, when the resin body 13 is made of a resin material with high mechanical strength, the mechanical strength of the chip coil 11 itself is high, but the stress caused by the expansion and contraction of the resin body 13 caused by heat cycles is applied directly to the winding W, so
There is a problem that the winding W is easily broken.

Therefore, in view of the above problems, the first problem of the present invention is to:
An object of the present invention is to provide an inductance element with high mechanical strength and less occurrence of wire breakage during thermal stress. The second problem is to provide an inductance element that solves the first problem and also has magnetic shielding properties.

Means for Solving the Problems In order to solve the first problem, the inductance element according to the present invention includes: (a) a covering made of a flexible resin material formed on the surface of the winding portion of the core; (b) an outer body made of a resin material with high mechanical strength formed on the surface of the covering body;

Furthermore, in order to solve the second problem, the inductance element according to the present invention is characterized in that at least one of the covering body and the outer body is impregnated with magnetic powder.

In other words, since the core has a covering body made of a flexible resin material and an outer body made of a resin material with high mechanical strength, the covering body acts as a buffer material and prevents the expansion of the outer body due to heat cycles. Prevent contraction stress from being applied directly to the windings wound around the core. The outer body increases the mechanical strength of the inductance element and prevents the covering from flowing when thermal shock is applied during soldering.

In addition, when the covering or the outer body is impregnated with magnetic powder, the covering or the outer body and the core form a closed magnetic path and exhibit magnetic shielding properties.

EXAMPLE Hereinafter, an example of an inductance element according to the present invention will be described using a chip coil 1 as an example.

As shown in FIG. 1, the chip coil 1 has a core 2 made of ferrite material or the like, and a winding W completely wound around the body 2a of the core 2.

A covering body 3 made of a flexible resin material is formed on the body portion 2a of the core 2, and covers the winding wire W. The flexible resin material is preferably a resin with low viscosity and high fluidity in order to completely fill the gaps between the windings W and between the windings and the core. For example, vinyl chloride resin, polyethylene, etc. are used. . Methods of granting include dip method,
There are dispenser methods, coating methods, mold methods, etc.

On the surface of the covering body 3, an outer body 4 made of a resin material with high mechanical strength is formed.9 The material of the resin material with high mechanical strength is preferably a resin with excellent heat resistance, such as thermosetting resin. Epoxy resin, phenol resin, etc., which are synthetic resins, are used. Application methods include a dip method, a dispenser method, a coating method, and a mold method.

The covering body 3 acts as a buffer material, and makes it difficult for external mechanical stress and stress due to expansion and contraction of the outer body 4 due to heat cycles during operation of the chip coil 1 to be applied directly to the winding W. Therefore, the covering 3 prevents the winding W from being disconnected, which would occur when the winding was covered using only a resin material with high mechanical strength.

The outer body 4 has a protective function such as increasing the mechanical strength of the chip coil 1 itself and preventing the covering body 3 from flowing due to thermal shock during soldering.

If the inductance element requires magnetic shielding, the resin covering 3 or the resin outer body 4 is impregnated with magnetic powder.

When the coating 3 is impregnated with magnetic powder, that is,
When a current flows through the winding W wound around the body 2a of the core 2, the generated magnetic flux is distributed between the body 2a of the core 2 - one base part 2b of the core 2 - the covering part 3a - the other side of the core 2 It passes through a closed magnetic path connecting the base portion 2c of the body 2a, the base portion 2b, the covering portion 3b, and the base portion 2C. As a result, the chip coil 1 can be completely magnetically shielded. Therefore, the resin covering 3 impregnated with magnetic powder not only covers and protects the winding W but also ensures magnetic shielding properties.

When the outer body 4 is impregnated with magnetic powder, the body part 2a-base part 2b-outer body part 4 of the core 2 is formed in the same manner as described above.
A closed magnetic path connecting the base portion 2C and a closed magnetic path connecting the body portion 2a, the base portion 2b, the outer body portion 4b, and the base portion 2C are formed. Thereby, the chip coil 1 is completely magnetically shielded. Therefore, the resin outer body 4 impregnated with magnetic powder increases the mechanical strength of the chip coil 1, protects the resin sheath 3, and at the same time ensures magnetic shielding properties.

Note that the inductance element according to the present invention is not limited to the above embodiments, and can be variously modified within the scope of the gist.

For example, it may be an inductance element in which both the covering body and the outer body are impregnated with magnetic powder.

Effects of the Invention As is clear from the above explanation, according to the inductance element of the present invention, the core is provided with a covering body made of a flexible resin material and an outer body made of a resin material with high mechanical strength. As a result, the covering acts as a buffer material, and mechanical stress from the outside as well as stress due to expansion and contraction of the outer body due to heat cycles is less likely to be applied directly to the winding, thereby preventing breakage of the winding. Since the outer body increases the mechanical strength of the inductance itself, it has the effect of eliminating phenomena such as neck bending in the coil of the drum lower quive, making it easier to handle when mounting the element. Furthermore, since the outer body prevents the covering from flowing when subjected to thermal shock during soldering, flow soldering can be used when mounting the element on a printed circuit board, making it compatible with soldering automation.

In addition, if the inductance element has a resin coating impregnated with magnetic powder or a resin outer body, the coating or outer body and the core form a closed magnetic path, so it has magnetic shielding properties. However, it is possible to provide an inductance element that has high mechanical strength and suppresses winding breakage during thermal stress.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a chip coil according to an embodiment of the present invention, and FIG. 2 is a partial sectional view of a conventional chip coil. 1...Inductance element (chip coil), 2...
・Core, 2a... body part, 2b, 2c... base part,
3...Resin covering body, 4...Resin outer body, W...
winding. Patent applicant Murata Manufacturing Co., Ltd.

Claims (3)

[Claims] 1. A covering body made of a flexible resin material formed on the surface of the winding portion of the core, and an outer body made of a mechanically strong resin material formed on the surface of the covering body. An inductance element characterized by: 2. 2. The inductance element according to claim 1, wherein the covering is impregnated with magnetic powder. 3. 2. The inductance element according to claim 1, wherein the outer body is impregnated with magnetic powder.