TW201405595A - Thin film type common mode filter - Google Patents

Abstract

The thin film type common mode filter of the instant disclosure includes an insulating substrate and a coil body structure thereon. The coil body structure comprises a first coil, a second coil, a third coil, and a fourth coil, wherein the first coil is connected in series with the third coil, and the second coil is connected in series with the fourth coil. Specially, a width W (mm) and a length L (mm) of the first coil, the second coil, the third coil, and the fourth coil satisfy the relational expression of: [(7.2-fc)/3.0]<SP>2</SP> < L/W < [(8.15-fc)/2.7]<SP>2</SP> Where fc (MHz) is the cutoff frequency with respect to differential-mode signal.

Description

Thin film common mode filter

The present invention relates to a common mode filter, and more particularly to a thin film common mode filter applied to a portable electronic device.

A common mode filter is an element for suppressing a common mode current, which causes electromagnetic interference (EMI) in a parallel transmission line, which is a source of noise in an electronic circuit. With the miniaturization of portable electronic devices, common mode filters used in portable electronic devices are often required to be miniaturized and high-density structures, so thin film and stacked common mode filters are gradually replacing the traditional winding type. Common mode filter.

Japanese Patent Publication No. JP2000173824A discloses an electronic component having an insulating substrate, a laminated body and an external electrode terminal portion; the laminated system is formed by alternately laminating a conductor pattern and an insulating layer on the insulating substrate, the external electrode terminal portion Electrically connected to the conductor pattern and formed across the insulating substrate and the laminate, wherein the electronic member is provided with a layer or a small piece made of a magnetic material for shielding at least a part of the conductor pattern.

However, in order to enhance the common mode impedance of such an electronic component, it is generally necessary to increase the number of windings of the coil of the conductor pattern, thereby causing the volume of the electronic component to become large. In addition, the prior art also discloses that the common mode impedance can be controlled by changing the conductor pattern of the laminated body. Since the conductor pattern is alternately laminated with the insulating layer, the structure is complicated and the number of process variations is large.

In view of this, the inventors have based on years of experience in the manufacturing development and design of related products, and after detailed design and careful evaluation of the above objectives, Finally, a practical invention is obtained.

In order to enhance and accurately control the common mode impedance, the present invention provides a thin film common mode filter which is simple in structure and can be effectively miniaturized. The thin film common mode filter sequentially includes a non-magnetic insulating substrate, a first a conductor layer, a first electrical insulation layer, a second conductor layer, a second electrical insulation layer, a third conductor layer, a third electrical insulation layer, a fourth conductor layer, an insulation layer and a magnetic material Floor.

The first conductor layer has a first coil, and the first conductor layer is disposed on the non-magnetic insulating substrate; the second conductor layer has a second coil, and the second conductor layer is disposed on the first conductor Above the layer; the first electrically insulating layer is disposed between the first conductor layer and the second conductor layer; the third conductor layer has a third coil, and the third conductor layer is disposed on the second conductor layer The second electrical insulating layer is disposed between the second conductive layer and the third conductive layer, wherein the first coil is connected to the third coil through the first electrical insulating layer and the second electrical insulating layer. The first coil and the third coil are used together to eliminate common mode noise.

Furthermore, the fourth conductor layer has a fourth coil, and the fourth conductor layer is disposed above the third conductor layer; the third electrical insulation layer is disposed between the third conductor layer and the fourth conductor layer The second coil is connected in series with the fourth coil through the second electrical insulation layer and the third electrical insulation layer, so that the second coil and the fourth coil together cancel common mode noise; the insulation layer is disposed. On the third electrical insulating layer; and the magnetic material layer is disposed on the insulating layer;

It is worth mentioning that the total length L (mm) and the width W (mm) of the first coil, the second coil, the third coil and the fourth coil satisfy a relational expression: [(7.2-fc) /3.0] ² <L/W<[(8.15-fc)/2.7] ² , where fc is the cutoff frequency of the differential mode signal.

In summary, in the thin film common mode filter of the present invention, the first coil and the third coil electrically connected in series can be magnetically coupled to each other to eliminate common mode noise, and the second coil and the fourth coil electrically connected in series Can also achieve the same effect. Thereby, the thin film common mode filter can control the cutoff frequency within a range, which does not need to increase the number of windings of the coil to enhance and accurately control the common mode impedance, and can be effectively miniaturized. In addition, the thin film common mode filter can accurately control the common mode impedance by placing the coils on the insulating substrate of the non-magnetic material, so that the cutoff frequency can be accurately controlled within an effective range.

Referring to FIG. 1, there is shown a perspective exploded view of a first embodiment of a thin film common mode filter 1 of the present invention. The thin film common mode filter 1 includes a non-magnetic insulating substrate 10 and a coil body stack. The structure 20, an insulating layer 30 and a magnetic material layer 40. The coil body stack structure 20 is disposed on the non-magnetic insulating substrate 10, and the magnetic material layer 40 is disposed on the coil body stack structure 20 through the insulating layer 30 to serve as a cover of the thin film common mode filter 1. In this embodiment, the insulating layer 30 may be a bonding layer, but is not limited thereto.

Specifically, the non-magnetic insulating substrate 10 may be aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), glass (Glass), quartz (Quartz) or other materials having a high dielectric constant and non-magnetic properties. An insulating substrate is produced. The coil body stack structure 20 sequentially includes a first conductor layer 21, a first electrical insulation layer 22, a second conductor layer 23, a second electrical insulation layer 24, a third conductor layer 25, a third electrical insulation layer 26, and a fourth conductor. Layer 27. The insulating layer 30 is disposed between the magnetic material layer 40 and the coil body stack structure 20, and the magnetic material layer 40 is overlaid on the coil body stack structure 20, thereby increasing the inductance effect of the thin film common mode filter 1.

Referring back to Figure 1, the specific features of the coil body stack structure 20 will be described below. The first conductive layer 21 is formed on one surface of the non-magnetic insulating substrate 10, and includes a first coil 211, a first electrode 212, a second electrode 213, a third electrode 214, and a fourth electrode 215. In more detail, the first coil 211 has an inner end portion 2111 and an outer end portion 2112, wherein the outer end portion 2112 is connected to the first electrode 212.

The second conductor layer 23 is formed on one surface of the first electrical insulating layer 22, that is, the second conductor layer 23 and the first conductor layer 21 are respectively disposed on opposite surfaces of the first electrical insulating layer 22. The second conductor layer 23 includes a second coil 231, a first electrode 232, a second electrode 233, a third electrode 234, and a fourth electrode 235. The second coil 231 has an inner end portion 2311 and an outer portion. The end portion 2312 and the outer end portion 2312 of the second coil 231 are connected to the third electrode 234.

The third conductor layer 25 is formed on one surface of the second electrical insulating layer 24, that is, the third conductor layer 25 and the second conductor layer 23 are respectively disposed on opposite surfaces of the second electrical insulating layer 24. The third conductor layer 25 includes a third coil 251, a first electrode 252, a second electrode 253, a third electrode 254, and a fourth electrode 255. The third coil 251 has an inner end portion 2511 and an outer portion. The end portion 2512 and the outer end portion 2512 of the third coil 251 are connected to the second electrode 253.

The fourth conductor layer 27 is formed on one surface of the third electrical insulating layer 26 That is, the fourth conductor layer 27 and the third conductor layer 25 are respectively disposed on opposite surfaces of the third electrical insulating layer 26. The fourth conductor layer 27 includes a fourth coil 271, a first electrode 272, a second electrode 273, a third electrode 274 and a fourth electrode 275. The fourth coil 271 has an inner end portion 2711 and an outer portion. The end portion 2712 and the outer end portion 2712 of the fourth coil 271 are connected to the fourth electrode 275.

In this embodiment, the first coil 211, the second coil 231, the third coil 251, and the fourth coil 271 may be rectangular spiral coils, but may be spiral coils of other shapes. In addition, the first coil 211, the second coil 231, the third coil 251, and the fourth coil 271 have the same number of windings, and the first coil 211, the second coil 231, the third coil 251, and the fourth coil 271 are vertical. The electrodes of the non-magnetic material are substantially overlapped in the direction of the insulating substrate 10, and the positions of the electrodes of the first conductor layer 21, the second conductor layer 23, the third conductor layer 25, and the fourth conductor layer 27 are perpendicular to the non-magnetic material. The insulating substrate 10 also substantially overlaps in the direction.

The first electrical insulating layer 22 is disposed between the first conductive layer 21 and the second conductive layer 23, and the first electrical insulating layer 22 defines a first connecting hole 221; the second electrical insulating layer 24 is disposed on the first A second connection hole 241 and a third connection hole 242 are defined in the second electrically conductive layer 24; the third electrically insulating layer 26 is disposed on the third conductor layer 25 and A fourth connecting hole 261 is defined in the fourth conductive layer 27 and on the third electrical insulating layer 26. The first connecting hole 221 and the second connecting hole 241 are located at opposite ends of the inner end portion 2111 of the first coil 211 and the inner end portion 2511 of the third coil 251, and the third connecting hole 242 and the fourth connecting hole 261 are located at the first end. Inner end 2311 and fourth of the second coil 231 The opposite end of the inner end 2711 of the coil 271.

It is worth mentioning that the inner end portion 2111 of the first coil 211 can be connected in series to the inner end portion 2511 of the third coil 251 through the first connection hole 221 and the second connection hole 241, and the inner end portion 2311 of the second coil 231. The third connection hole 242 and the fourth connection hole 261 may be connected in series to the inner end portion 2711 of the fourth coil 271, whereby the first coil 211 and the third coil 251 are connected in series, and the second coil 231 and the fourth coil are connected in series. 271 can be magnetically coupled to each other to eliminate common mode noise.

Please refer to FIG. 2 , which is a schematic diagram showing the relationship between the cutoff frequency generated by the thin film common mode filter 1 and the total length L (mm) of each coil divided by the line width W (mm). It can be seen that each of the cutoff frequencies corresponding to the total length L (mm) divided by the line width W (mm) nodes fall within the range of the first trend line G1 and the second trend line G2, that is, the thin film common mode filter The resulting cutoff frequency is roughly between 2.5 and 5.5 MHz, meeting the needs of a particular portable electronic device.

In more detail, the thin film common mode filter 1 is configured such that the first coil 211, the second coil 231, the third coil 251, and the fourth coil 271 having a rectangular spiral shape are disposed on an insulating substrate of a non-magnetic material, and It is preferably an alumina substrate, and therefore can satisfy the following relational expression: [(7.2-fc)/3.0] ² <L/W<[(8.15-fc)/2.7] ²

In addition, in the specific embodiment, the first conductor layer 21, the second conductor layer 23, the third conductor layer 25, and the fourth conductor layer 27 may be subjected to a plurality of processes such as thin film metal deposition, yellow light lithography, and etching, or by A plating process and a sputtering process are formed, and the first conductor layer 21, the second conductor layer 23, the third conductor layer 25, and the fourth conductor layer 27 may be selected from silver (Ag), palladium (Pd), aluminum (Al), Chromium (Cr), nickel (Ni), titanium (Ti), gold (Au), copper (Cu) or platinum (Pt) as The material of the conductor.

The first electrical insulating layer 22, the second electrical insulating layer 24 and the third electrical insulating layer 26 may be selected from polyimide, epoxy resin or benzocyclobutene (BCB). Electrically insulating materials which have preferred electrical and mechanical properties and which can be formed by a spin coating process. The magnetic material layer 40 may be a magnetic substrate or a colloid of a mixed magnetic powder, and is also formed by a spin coating process, wherein the colloid of the mixed magnetic powder may be a magnetic powder and a polyimide, an epoxy resin ( Epoxy resin), benzocyclobutene resin (BCB) or other high molecular polymer mixture.

[Second embodiment]

Referring to Figure 3, there is shown a perspective exploded view of a second embodiment of a thin film common mode filter 1' of the present invention. The difference from the previous embodiment is that the thin film common mode filter 1' includes a first magnetic material layer 40A and a second magnetic material layer 40B, wherein the first magnetic material layer 40A is pasted through the insulating layer 30. On the coil body stack structure 20, the second magnetic material layer 40B is disposed between the coil body stack structure 20 and the non-magnetic material insulating substrate 10.

In more detail, the first magnetic material layer 40A is disposed on the insulating layer 30 and is disposed on the fourth conductive layer 27, and the second magnetic material layer 40B is disposed between the first conductive layer 21 and the non-magnetic insulating substrate 10. A higher common mode noise filtering effect can be achieved. Similarly, the thin film common mode filter 1' can precisely control the cutoff frequency it produces, and satisfies the following relational expression: [(7.2-fc)/3.0] ² <L/W<[(8.15-fc And 2.7] ^2, where L is the total length of the first coil 211, the second coil 231, the third coil 251, and the fourth coil 271, and W is the first coil 211, the second coil 231, the third coil 251, and the The width of the four coils 271, fc is the cutoff frequency of the differential mode signal, and the cutoff frequency is approximately between 2.5 and 5.5 MHz.

[Third embodiment]

Referring to Figure 4, there is shown a perspective exploded view of a third embodiment of a thin film common mode filter 1" of the present invention. The thin film common mode filter 1" further includes a plurality of magnetic portions 50. Specifically, the magnetic portions 50 are ferrite cores having a high magnetic permeability and high resistance and small eddy current loss over a wide frequency range.

In addition, a through hole 222, 243, 262 is defined in each of the first electrical insulating layer 22, the second electrical insulating layer 24 and the third electrical insulating layer 26, and the magnetic portions 50 pass through the first electrical insulating layer 22 and the second electrical The through holes 222, 243, and 262 of the insulating layer 24 and the third electrical insulating layer 26 are disposed inside the first coil 211, the second coil 231, the third coil 251, and the fourth coil 271 to enhance the thin film common mode filtering. The stability of the device 1" can increase the magnetic path region between the electrical insulating layers, thereby increasing the impedance of the thin film common mode filter 1".

In addition, the thin film common mode filter 1" can also precisely control the cutoff frequency it produces, satisfying the following relational expression: [(7.2-fc)/3.0] ² <L/W<[(8.15-fc)/2.7 ] ² where, L is a first coil 211, second coil 231, the total length of the third coil 251 and fourth coil 271, W is a first coil 211, second coil 231, third coil 251 and fourth coil 271 The width, fc is the cutoff frequency of the differential mode signal, and the cutoff frequency is roughly between 2.5 and 5.5 MHz, which meets the requirements of specific portable electronic devices.

In summary, in the thin film common mode filter of the present invention, the first coil and the third coil electrically connected in series can be magnetically coupled to each other to eliminate common mode noise, and the second coil and the fourth coil electrically connected in series Can also achieve the same effect. Thereby, the thin film common mode filter can enhance the resistance of the common module without increasing the number of windings of the coil in the conductor layer, and the structure of the thin film common mode filter can be further thinned, It is applied to various miniaturized portable electronic devices.

Furthermore, the thin film common mode filter has the conductor layers and their coils disposed on an insulating substrate having a high dielectric constant of a non-magnetic material, so that the common mode impedance can be precisely controlled, so that the cutoff frequency can be Precise control within a valid range can satisfy a relational expression: [(7.2-fc)/3.0] ² <L/W<[(8.15-fc)/2.7] ² , and the cutoff frequency fc is approximately 2.5 to Between 5.5 MHz, it meets the needs of specific portable electronic devices.

1, 1', 1" ‧ ‧ film common mode filter

10‧‧‧Insulating substrate of non-magnetic material

20‧‧‧ coil body stack structure

21‧‧‧First conductor layer

211‧‧‧First coil

2111‧‧‧Inside

2112‧‧‧Outer end

212‧‧‧First electrode

213‧‧‧second electrode

214‧‧‧ third electrode

215‧‧‧fourth electrode

22‧‧‧First electrical insulation

221‧‧‧First connection hole

222‧‧‧through hole

23‧‧‧Second conductor layer

231‧‧‧second coil

2311‧‧‧Inside

2312‧‧‧Outer end

232‧‧‧first electrode

233‧‧‧second electrode

234‧‧‧ third electrode

235‧‧‧fourth electrode

24‧‧‧Second electrical insulation

241‧‧‧Second connection hole

242‧‧‧ third connection hole

243‧‧‧through hole

25‧‧‧3rd conductor layer

251‧‧‧third coil

2511‧‧‧Inside

2512‧‧‧Outer end

252‧‧‧First electrode

253‧‧‧second electrode

254‧‧‧ third electrode

255‧‧‧fourth electrode

26‧‧‧ Third electrical insulation

261‧‧‧fourth connection hole

262‧‧‧through hole

27‧‧‧4th conductor layer

271‧‧‧fourth coil

2711‧‧‧Inside

2712‧‧‧Outer end

272‧‧‧First electrode

273‧‧‧second electrode

274‧‧‧ third electrode

275‧‧‧fourth electrode

30‧‧‧Insulation

40‧‧‧ Magnetic material layer

40A‧‧‧First magnetic material layer

40B‧‧‧Second magnetic material layer

50‧‧‧Magnetic Department

G1, G2‧‧‧ trend line

1 is a perspective exploded view of a specific embodiment of a thin film common mode filter of the present invention; FIG. 2 is a schematic diagram showing the relationship between the cutoff frequency generated by the thin film common mode filter of the present invention and the total length of the coil divided by the width; 3 is an exploded perspective view of another embodiment of the thin film common mode filter of the present invention; and FIG. 4 is an exploded perspective view of still another embodiment of the thin film common mode filter of the present invention.

1‧‧‧Thin-film common mode filter

10‧‧‧Insulating substrate of non-magnetic material

20‧‧‧ coil body stack structure

21‧‧‧First conductor layer

211‧‧‧First coil

2111‧‧‧Inside

2112‧‧‧Outer end

212‧‧‧First electrode

213‧‧‧second electrode

214‧‧‧ third electrode

215‧‧‧fourth electrode

22‧‧‧First electrical insulation

221‧‧‧First connection hole

23‧‧‧Second conductor layer

231‧‧‧second coil

2311‧‧‧Inside

2312‧‧‧Outer end

232‧‧‧first electrode

233‧‧‧second electrode

234‧‧‧ third electrode

235‧‧‧fourth electrode

24‧‧‧Second electrical insulation

241‧‧‧Second connection hole

242‧‧‧ third connection hole

25‧‧‧3rd conductor layer

251‧‧‧third coil

2511‧‧‧Inside

2512‧‧‧Outer end

252‧‧‧First electrode

253‧‧‧second electrode

254‧‧‧ third electrode

255‧‧‧fourth electrode

26‧‧‧ Third electrical insulation

261‧‧‧fourth connection hole

27‧‧‧4th conductor layer

271‧‧‧fourth coil

2711‧‧‧Inside

2712‧‧‧Outer end

272‧‧‧First electrode

273‧‧‧second electrode

274‧‧‧ third electrode

275‧‧‧fourth electrode

30‧‧‧Insulation

40‧‧‧ Magnetic material layer

Claims (10)

A thin film common mode filter is disposed on a portable electronic device for eliminating common mode noise generated by the operation of the electronic circuit of the portable electronic device. The thin film common mode filter includes: An insulating substrate of a non-magnetic material; a first conductor layer having a first coil, the first conductor layer being disposed on the insulating substrate of the non-magnetic material; and a second conductor layer having a second coil, the second conductor a layer is disposed above the first conductor layer; a first electrical insulation layer disposed between the first conductor layer and the second conductor layer; a third conductor layer having a third coil, the third a conductor layer is disposed above the second conductor layer; a second electrical insulation layer is disposed between the second conductor layer and the third conductor layer, wherein the first coil passes through the first electrical insulation layer The second electrically insulating layer is electrically connected in series with the third coil for causing the first coil and the third coil to cancel common mode noise; a fourth conductor layer having a fourth coil, the fourth conductor layer Provided above the third conductor layer a third electrically insulating layer disposed between the third conductor layer and the fourth conductor layer, wherein the second coil is electrically connected in series with the third electrically insulating layer by the second electrically insulating layer. a coil for preventing the second coil and the fourth coil together to eliminate common mode noise; an insulating layer disposed on the third electrical insulating layer; and a magnetic material layer disposed on the insulating layer; The total length L (mm) and the width W (mm) of one of the first coil, the second coil, the third coil, and the fourth coil satisfy a relational expression: [(7.2-fc) /3.0] ² <L/W<[(8.15-fc)/2.7] ² , where fc is the cutoff frequency of the differential mode signal. The thin film common mode filter according to claim 1, wherein the non-magnetic insulating substrate is an aluminum oxide (Al ₂ O ₃ ) substrate, an aluminum nitride (AlN) substrate, a glass substrate or quartz. (Quartz) substrate. The thin film common mode filter according to claim 1, further comprising another magnetic material layer disposed between the insulating substrate of the non-magnetic material and the first conductive layer. The film-type common mode filter according to claim 1, further comprising a plurality of magnetic portions, wherein the first electrical insulating layer, the second electrical insulating layer and the third electrical insulating layer are each provided with a through hole. The magnetic portions are disposed on the inner side of the first coil, the second coil, the third coil, and the fourth coil through the through holes of the first electrical insulating layer, the second electrical insulating layer, and the third electrical insulating layer . The film-type common mode filter according to claim 1, wherein the first coil, the second coil, the third coil, and the fourth coil have an inner end portion and an outer end portion, the first a first connecting hole is disposed on an electrical insulating layer, a second connecting hole and a third connecting hole are disposed on the second electrical insulating layer, and a fourth connecting hole is disposed on the third air insulating layer, the first connecting The hole and the second connecting hole are located at an inner end of the first coil and an inner end of the third coil, and the third connecting hole and the fourth connecting hole are located at an inner end of the second coil The opposite of the inner end of the fourth coil. The thin film common mode filter of claim 1, wherein an inner end of the first coil passes through the first connection hole and the second connection hole The inner end of the third coil is electrically connected in series, and the inner end of the second coil is electrically connected in series with the inner end of the fourth coil through the third connecting hole and the fourth connecting hole. The thin film common mode filter according to claim 1, wherein the first coil, the second coil, the third coil, and the fourth coil have a rectangular spiral shape. The thin film common mode filter according to claim 1, wherein the material of the first electrical insulating layer, the second electrical insulating layer and the third electrical insulating layer is polyamine, epoxy or benzo Cyclobutene resin. The thin film common mode filter according to claim 1, wherein the first conductor layer, the second conductor layer, the third conductor layer and the fourth conductor layer are made of silver, palladium, aluminum or chromium. , nickel, titanium, gold, copper or platinum. The thin film common mode filter according to claim 1, wherein the magnetic material layer is a magnetic substrate or a colloid mixed with a magnetic powder.