KR101213239B1 - planar inductor - Google Patents

Abstract

The present invention discloses a planar inductor using a multi-layer printed circuit board having a coil pattern and improving the shape of internal and external cores to reduce inductance, and the planar inductor has an inlet at a bottom thereof. An outer core formed of a ferrite material having a cylindrical shape having a cylindrical storage space communicated with the inlet; A plate having the same diameter as the outer core and an inner core of the ferrite material formed integrally with a cylinder formed at the center of the plate to be coupled to the outer core; And a through hole into which the cylinder of the inner core is inserted, and has a ring-shaped outer shape and is housed in the storage space of the outer core and wound from the center to the outside, the coil pattern is formed in multiple layers, and is provided at both ends of the coil pattern. And a multi-layer printed circuit board having lead holes for electrical connection, respectively, wherein the through-holes are formed in the plate of the inner core to extend the lead holes of the multi-layer printed circuit board.

Description

Planar Inductor

The present invention relates to a planar inductor, and more particularly, by using a multi-layer printed circuit board having a coil pattern and improving the shape of the inner and outer cores to reduce the height to be suitable for slim electronic products. At the same time, the present invention relates to a planar inductor with improved inductance reduction.

As electronic products gradually become thinner and smaller, the size of electronic components required for electronic products such as flat-panel televisions has become smaller.

To meet this trend, surface-mount inductors have been developed and are widely used in electronic products.

Ferrite used in the core configuration of the inductor is a brittle material and has a physical property that does not absorb external shocks and is easily broken. Therefore, the smaller the inductor has a problem in reliability due to the above characteristics of the ferrite material forming the core.

In addition, the smaller the inductor has a problem that the capacity is reduced because the coil is wound less.

A conventional inductor will be described in more detail with reference to FIGS. 1 to 6.

1 is a photograph of a core and an inductor for an example of a conventional surface mount inductor, and FIG. 2 is a photograph of a core and an inductor for another example of a conventional surface mount inductor.

1 and 2, the picture on the upper left is the outer core and the picture on the upper right is the inner core. 1 and 2 are photographs of the surface mounted inductor in which the outer core and the inner core are coupled after the coil work is completed.

Conventional surface mount inductors such as FIGS. 1 and 2 have a structure as shown in FIG. 3.

3 is a partial cutaway view of an assembled state of a conventional surface mount inductor.

In FIG. 3, the inner core 10 and the outer core 12 have a bottom portion bonded to the lower plate, that is, the substrate 14, and an epoxy 16 attached to the upper portion thereof. Here, the inner core 10 and the outer core 12 are made of a ferrite material.

The conventional surface mount inductor having the structure as shown in FIG. 3 has a problem in that ferrite is destroyed by thermal stress.

This will be described with reference to FIGS. 4 and 5.

4 is a simulated chart for analyzing stress caused by thermal stress of a conventional surface mount inductor, and FIG. 5 is a photograph of an actual surface mount inductor used in the analysis of FIG. 4.

Referring to FIG. 4, it can be seen that in the conventional surface mount inductor, maximum stress occurs in the upper portion A bonded by the epoxy 16 and the lower portion B bonded to the substrate 14. Here, areas A and B of FIG. 4 correspond to areas A and B of FIG. 5.

In FIG. 4, the upper part A and the lower part B in which the maximum stress occurs are included in the main failure mechanism of the conventional surface mount inductor. The specific reason for the failure is that the ferrite breaks due to thermal stress under thermal shock conditions because the internal core 10 and the outer core 12 of the ferrite material have different thermal expansion coefficients from the substrate 14 or epoxy 16, which is a lower plate. There is this.

In addition, in the conventional surface mount inductor, magnetic field leakage occurs in a gap Gap between the inner core 10 and the outer core 12, which are ferrite materials.

6 is a diagram illustrating a phenomenon in which the permeability decreases in the gap between ferrites. Referring to FIG. 6, the larger the gap Gap is, the more magnetic field leakage occurs and the magnetic flux density is changed, so that the permeability is reduced.

That is, the larger the air gap, the lower the permeability, and this phenomenon can be explained by Equation 1 below.

As shown in Equation 1, the larger the Ig, the lower the permeability B, and the decrease in the permeability B causes the inductance L to decrease as shown in Equation 2 below.

Conventional surface mount inductors have gaps in the top and bottom, and also have a large gap bonded by the epoxy (16). Therefore, the conventional surface mount inductor has a problem that the magnetic permeability is reduced due to the magnetic permeability and consequently the inductance is reduced.

In addition, conventional surface mount inductors are designed to be high in height to have sufficient capacity. Therefore, when mounted in a product such as a flat panel display device, a problem occurs due to the height of the inductor's enclosure. Therefore, there is a need to present an inductor having a structure that can be downsized in height so that there is no problem when it is mounted on a product that is thin and downsized.

An object of the present invention is to provide a planar inverter having a structure that can prevent the occurrence of ferrite fracture due to thermal stress in thermal shock conditions.

Another object of the present invention is to provide a planar inverter having a structure capable of minimizing a reduction in inductance by reducing a portion in which a gap in which magnetic field occurs is generated.

In addition, another object of the present invention is to provide a planar inverter having a structure of a low height so that there is no difficulty when mounting on a product that is thin and compact.

According to an aspect of the present invention, there is provided a planar inductor including: an outer core having a cylindrical shape having an inlet formed at a bottom thereof, and having a cylindrical shape having a cylindrical storage space communicated with the inlet; A plate having the same diameter as the outer core and an inner core of the ferrite material formed integrally with a cylinder formed at the center of the plate to be coupled to the outer core; And a through hole into which the cylinder of the inner core is inserted, and has a ring-shaped outer shape and is housed in the storage space of the outer core and wound from the center to the outside, the coil pattern is formed in multiple layers, and is provided at both ends of the coil pattern. And a multi-layer printed circuit board having lead holes for electrical connection, respectively, wherein the through-holes are formed in the plate of the inner core to extend the lead holes of the multi-layer printed circuit board.

Here, the lead wire and the lead wire which is inserted into the through hole communicated with each other is further configured, the lead wire is preferably in electrical connection with the end of the coil pattern.

The coil pattern may be formed to have a spiral shape.

Each end of the coil pattern formed in the multilayer is preferably electrically connected to one lead wire, respectively.

According to the present invention, since the inner core and the outer core of the ferrite material are assembled to face a gap at the bottom thereof, the inner core or the outer core of the surface-mount inductor can be prevented from being destroyed due to the difference in thermal expansion coefficient under thermal shock conditions. It works.

In addition, according to the present invention, as the structure is improved such that only one gap exists between the inner core and the outer core, the surface mounted inductor may minimize the reduction of inductance.

In addition, according to the present invention, since a multilayer printed circuit board having a coil pattern is used, the designed height can be significantly lowered while ensuring sufficient capacity, thereby making it easy to mount a product having a thin and small surface-mount inductor. .

1 is a photograph of a core and an inductor for an example of a conventional surface mount inductor.
2 is a photograph of a core and an inductor for another example of a conventional surface mount inductor.
3 is a partial cutaway view of an assembled state of a conventional surface mount inductor.
Figure 4 is a simulated chart to analyze the stress caused by the thermal stress of the conventional surface-mount inductor.
FIG. 5 is a photograph of an actual surface mount inductor used in the analysis of FIG. 4.
6 is a diagram illustrating a phenomenon in which the permeability decreases in the gap between ferrites.
7 is an exploded perspective view showing a preferred embodiment of the planar inductor according to the present invention.
8 is a cross-sectional view of a state in which the planar inductor according to the present invention is assembled.
9 is a plan view of the multilayered printed circuit board of FIGS. 7 and 8.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. It doesn't happen.

The planar inductor according to the present invention includes an outer core 10, an inner core 20, and a multilayer printed circuit board 30, as shown in FIGS. 7 and 8, and has a surface mount type.

Here, Figure 7 is an exploded perspective view showing a preferred embodiment of the planar inductor according to the present invention, Figure 8 is a cross-sectional view of the assembled state of the planar inductor according to the present invention. For convenience of description in FIG. 8, the multi-layer printed circuit board 30 does not indicate hatching of a cross section.

The outer core 10 is made of a ferrite material and has a cylindrical shape having an inlet formed at a bottom thereof and having a cylindrical storage space communicating with the inlet.

By the above-described shape, the outer core 10 is coupled to the inner core 20 disposed below and has a configuration for accommodating the multilayer printed circuit board 30 in the storage space.

 In addition, the inner core 20 has a plate 22 having the same diameter as the outer core 10 and a cylinder 24 formed at the center of the plate 22 are integrally formed and made of a ferrite material.

The outer core 10 is seated and coupled to the upper plate 22 of the inner core 20, the junction surface of the inner surface of the core 22 and the bottom surface of the outer core 10 is in contact with the gap Becomes

The multilayered printed circuit board 30 is accommodated in the storage space of the outer core 10 while the inner core 20 and the outer core 10 are coupled to each other.

The multilayer printed circuit board 30 has a through-hole 34 through which the cylinder 24 of the inner core 20 is inserted at the center thereof, and has a ring-shaped appearance.

The multilayer printed circuit board 30 has a multilayer coil pattern 32 and the coil patterns 32 can be prevented from breakdown by the printed circuit board interposed therebetween.

In addition, the coil pattern 32 of the multilayer printed circuit board 20 is formed to have a shape wound from the center to the outside, and preferably, the pattern may be formed to have a spiral shape as shown in FIG. 9.

For reference, FIG. 9 is a plan view of the multilayer printed circuit board 20, and the coil patterns 32 have a configuration in which the layers are overlapped in the same pattern for each layer.

Lead holes 36 and 38 are formed at positions where both ends of each layer coil pattern 32 formed in the multilayer printed circuit board 20 are formed, and internal cores 20 corresponding to the lead holes 36 and 38 are formed. In the plate 22 of the through holes 26, 28 are formed, respectively.

That is, the lead holes 36 and 38 of the multilayer printed circuit board 20 and the through holes 26 and 28 of the inner core 20 are connected to each other and extend to each other. This is made up.

The lead wire 40 penetrates through the lead holes 36 and 38 and the through holes 26 and 28 and is electrically connected to each end of the coil pattern 32 of each layer to the multilayer printed circuit board 20.

Accordingly, the coil patterns 32 stacked in multiple layers on the multilayer printed circuit board 30 are connected to lead wires 40 corresponding to one end of each coil pattern 32. Therefore, since the lead wire 40 is directly drawn to the outside from the multilayer printed circuit board 30, it is not necessary to configure a plate for wiring like a conventional inductor.

In the planar inductor according to the present invention configured as described above, the overall height may be determined according to the thickness of the multilayer printed circuit board 30.

That is, the multilayer printed circuit board 30 may form the coil pattern 32 in a large number of layers, and thus may be manufactured to have a relatively low height as compared with a conventional inductor.

In addition, the inner core 20 and the outer core 10 of the planar inductor according to the present invention serve to provide a passage of the magnetic field.

That is, the multilayer printed circuit board 30 formed in a ring type forms a solenoid and forms a magnetic field around itself when a current is supplied through the lead wire 40. At this time, the formed magnetic field is induced to flow through the inner core 20 and the outer core 10.

The planar inductor according to the present invention is configured to have one gap, the gap consisting of a junction between ferrites. Therefore, magnetic field leakage due to multiple gaps can be minimized, and as a result, a decrease in permeability can be suppressed and a decrease in inductance can be reduced.

10: outer core 20: inner core
22 plate 24 cylinder
26, 28: through hole 30: multilayer printed circuit board
32: coil pattern 34: through hole
36, 38: lead hole 40: lead wire

Claims (4)

An outer core of a ferrite material having a cylindrical shape having an inlet formed at a bottom thereof and having a cylindrical storage space communicating with the inlet;
An inner core of the ferrite material coupled to the outer core; And
And a multilayer printed circuit board accommodated in the cylindrical accommodating space of the outer core.
The inner core is formed integrally with a disk formed in the center of the disk-shaped plate and the disk-shaped plate having the same diameter as the outer core,
The outer core is seated and coupled to an upper portion of the plate of the inner core,
The multilayer printed circuit board has a ring-type outer shape having a through hole through which the cylinder of the inner core is inserted in the center thereof.
The multilayer printed circuit board is accommodated in a cylindrical accommodating space of the outer core having a cylindrical shape to form a structure surrounded by the outer core.
The multilayer printed circuit board has a coil pattern wound from the center to the outside in a multilayer manner,
Lead holes for electrical connection are formed at both ends of the coil pattern,
The plate of the inner core is formed with through holes extending to the lead holes of the multilayer printed circuit board,
A lead wire inserted into the lead hole and the through hole communicating with each other,
The lead wire makes an electrical connection with an end of the coil pattern,
And the coil pattern is formed to have a spiral shape.
delete delete The method of claim 1,
Each end of the coil pattern formed in a multi-layered planar inductor each in common electrical connection to one lead wire.

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