Wire wound electronic component

Details Wire wound electronic component Wire wound electronic component

1998-08-07

2001-03-06

Donovan, Lincoln (Department: 2832)

Inductor devices

Core forms casing

C336S090000, C336S096000

Reexamination Certificate

active

06198373

ABSTRACT:

FIELD OF THE ART
The present invention relates to an inductor, transformer, choke coil, common mode choke coil or similar wire wound electronic component.
BACKGROUND ART
A wire wound electronic component has a structure as shown in FIG.
14
(A). In this FIG.
14
(A), at both ends of the core
10
, whereon a wire is wound and whose shape is a column having a circle (oval, rectangular or similar shape) cross-section, has flanges
12
and
14
having a prism shape (or a plank shape with a rectangular cross-section) are formed. The core
10
and the flanges
12
and
14
, all of which are made of magnetic materials, e.g., ferrite, form a coil bobbin
16
. Electrodes
18
and
20
are formed on each side and end surfaces of the flanges
12
and
14
respectively.
The conductor
22
is wound on the core
10
formed at the central portion of the coil bobbin
16
. The lead wires
24
and
26
at both ends of the conductor
22
are connected to the electrodes
18
and
20
respectively at each of side surfaces of the flanges
12
and
14
. A concave portion formed between flanges
12
and
14
is coated with a sealing resin
28
to cover the conductor
22
. The electrodes
18
and
20
whereto the lead wires
24
and
26
are respectively connected are applied with plates
30
and
32
respectively.
The above sealing resin
28
is made of, e.g., epoxy resin wherein ferrite powder is mixed as disclosed in Japanese Patent Laid-Open Publication No. 63-236305. Main components of the ferrite powder to be used for this purpose are, e.g., iron oxide, nickel oxide, zinc oxide, and copper oxide. Addition of the ferrite powder improves the magnetic shielding effect of the sealing resin
28
as shown by the dotted lines in
FIG. 14
, because it will allow a magnetic flux
34
to easily pass through inside the sealing resin
28
. It will also enable to reduce magnetic effects exerted on the adjacent components, and improve the inductance of a wire wound electronic component.
When an electric current is passed through the conductor
22
of a wire wound electronic component having a structure described above, it generates heat. Ferrite used in the coil bobbin
16
and ferrite powder used as a filler for the sealing resin
28
changes the magnetic permeability (&mgr;) thereof which shows the magnetic characteristics, along with its thermal changes. Accordingly, similar to other ordinary electronic components, it requires good thermal radiation. In terms of mounting, it requires a good countermeasure to prevent generation of static electricity for preventing the components from sticking to each other.
In addition, when there is not a close contact between the coil bobbin
16
and the sealing resin
28
, as shown by the arrow FA in
FIG. 14
, water will enter into cracks of the component from the joint portion of the flange
12
(or
14
) with the sealing resin
28
, thereby reliability of the component will be deteriorated. The cracks will also cut the current of the magnetic flux
34
at the above joint portion, thereby the magnetic shielding effect and inductance will be lowered. If there is a pinhole
36
in the sealing resin
28
, water will also enter inside the component as shown by the arrow FB.
If ferrite content is raised to increase the inductance, fine ferrite powder particles
38
may be strung from the surface of the sealing resin
28
to the coil bobbin
16
or the conductor
22
. In this case, water might also enter into the component along with the surface of the strung fine ferrite powder particles
38
as shown by the arrow FC. The same thing might happen when the surface of the fine ferrite powder particles
38
do not have wettability towards the resin materials.
Ferrite powders filled into the sealing resin
28
are made by burning generally at high temperature over 1000° C. Accordingly, the sintered ferrite substance becomes hard due to strong cohesion between the particles, and the size of the ferrite powder particles made by pulverization of the above ferrite substance might easily be varied. When those ferrite powder particles with uneven sizes are mixed into the above mentioned sealing resin for using an wire wound electronic component, it will suffer from several problems, i.e., deterioration of applicability of the sealing resin, unstable magnetic characteristic in the portion of the sealing resin, or similar problem. In other words, this would change the magnetic permeability in the portion of the sealing resin, thereby each component inductance would be changed. In addition, because a high internal stress will change inductance along with the change of magnetic permeability of the coil bobbin, as well as it would cause a damage of the coil bobbin, a break of the conductor or similar problem, relaxation of the internal stress might be desirable.
Filling ferrite powder into the resin will raise the viscosity of a sealing resin as a whole. When a sealing resin of high viscosity is used for coating and forming, the sealing resin will have less applicability than a sealing resin of low viscosity, and it will also requires high forming pressure. This high forming pressure accordingly exerts large stress on the coil bobbin
16
and conductor
22
. This might cause a crack at, e.g., the joint portion of the flanges
12
and
14
with the core
10
because the portion is more vulnerable, or might cause a break of the conductor
22
.
In addition, changes of stress will change the inductance. On one hand, this may cause deterioration of the component quality due to uneven quality, on the other hand, this may cause less manufacturing efficiency to produce the components with even quality.
The present invention, paying attention to the points stated above, has objectives to improve the thermal radiation, resistance against water and static electricity, and have better reliability of a wire wound electronic component.
Another objective is to obtain a sealing resin with stable magnetic characteristics and low internal stress by controlling the size of ferrite powder particles as a filler, as well as to retain good magnetic shielding effect.
In addition, another objective is to have efficient productivity of a wire wound electronic component with good quality by controlling change of inductance attributed to change of stress, as well as to protect a coil bobbin and wire by relieving stresses.
DISCLOSURE OF THE INVENTION
The present invention is characterized by addition of powder of high thermal conductive material into the above resin in a wire wound electronic component whose conductor wound on the coil bobbin is sealed with a resin material. Another configuration of the present invention comprising a wire wound electronic component whose conductor wound on the coil bobbin is sealed with a resin material including additives is characterized by hydrophobic surface treatment which coats the above additives. Another configuration of the present invention comprising a wire wound electronic component whose conductor is sealed with a sealing resin is characterized by a multi-layer structure of the above resin comprising an ordinary resin and a ferrite-mixed resin. In addition, another configuration of the present invention is characterized by relaxation material added to at least one of a coil bobbin and a sealing resin.
A method of producing a wire wound electronic component of the present invention is characterized by comprising the steps of winding a conductor around a coil bobbin; applying a thermosetting resin or a thermoplastic resin on the coil bobbin after the wire-winding step; application of heat and vibration to a block after application of the resin and placing thereof into magnetic powders. A filler to the sealing resin for a wire wound electronic component of the present invention is characterized by being produced by pulverizing the mixture whose main ingredients are Fe
2
O
3
, NiO, ZnO, CuO after burning thereof.
Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detaile

Affiliated with

Also associated with

Rating

Wire wound electronic component does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Wire wound electronic component, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wire wound electronic component will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2435840