Common mode filter

Abstract

The present invention improves high-frequency characteristics of a common mode filter by reducing line-to-line capacitance in a section close to a terminal electrode. A common mode filter (1) is provided with conductor layers (100, 200) and terminal electrodes (E1-E4), which are laminated with an insulating layer therebetween. The conductor layer (100) has a spiral coil pattern (110), the outer peripheral end of which is connected to the terminal electrode (E1) and the inner peripheral end of which is connected to the terminal electrode (E3). The conductor layer (200) has a coil pattern (210), the outer peripheral end of which is connected to the terminal electrode (E2) and the inner peripheral end of which is connected to the terminal electrode (E4). The outermost peripheral turn (111) of the coil pattern (110) has a non-overlapping section (S1) that surrounds the outermost peripheral turn (211) of the coil pattern (210) without overlapping with the outermost peripheral turn (211) of the coil pattern (210), or the innermost peripheral turn (112) of the coil pattern (110) has a non-overlapping section (S2) that surrounds the innermost peripheral turn (212) of the coil pattern (210) without overlapping with the innermost peripheral turn (212) of the coil pattern (210).

Description

Technical Field

[0001] The present invention relates to a common mode filter, and more particularly to a common mode filter including a plurality of coil patterns stacked with an insulating layer interposed therebetween. Background Art

[0002] Patent Document 1 discloses a chip-type common mode filter including a plurality of coil patterns stacked with an insulating layer interposed therebetween.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-139368 Summary of the Invention

[0006] In this common mode filter, the inter-line capacitance between coil patterns affects the high-frequency characteristics.

[0007] The present invention describes a technique for improving high-frequency characteristics by reducing inter-line capacitance in a section close to a terminal electrode in a common mode filter having a plurality of coil patterns stacked with an insulating layer interposed therebetween.

[0008] A common mode filter according to one aspect of the present invention comprises: a plurality of conductor layers stacked with an insulating layer therebetween, including at least a first and a second conductor layer; and first, second, third and fourth terminal electrodes, the first conductor layer having a first spiral coil pattern with an outer peripheral end connected to the first terminal electrode and an inner peripheral end connected to the third terminal electrode, the second conductor layer having a second spiral coil pattern with an outer peripheral end connected to the second terminal electrode and an inner peripheral end connected to the fourth terminal electrode, the outermost turn of the first coil pattern having a first non-overlapping section that surrounds the outermost turn of the second coil pattern without overlapping with the outermost turn of the second coil pattern over at least 1 / 4 of the turn, or the innermost turn of the first coil pattern having a second non-overlapping section that surrounds the innermost turn of the second coil pattern without overlapping with the innermost turn of the second coil pattern over at least 1 / 4 of the turn.

[0009] According to the present invention, there is provided a technique for improving high-frequency characteristics by reducing inter-line capacitance in a section close to a terminal electrode in a common mode filter having a plurality of coil patterns stacked with an insulating layer interposed therebetween. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic perspective view showing the appearance of a common mode filter 1 according to a first embodiment of the technology according to the present invention.

[0011] Figure 2 It is a schematic plan view for explaining the pattern shape of the conductive layer 100 .

[0012] Figure 3It is a schematic plan view of the insulating layer 10 .

[0013] Figure 4 It is a schematic plan view for explaining the pattern shape of the conductive layer 200 .

[0014] Figure 5 It is a schematic top view of the insulating layer 20 .

[0015] Figure 6 It is a schematic plan view for explaining the pattern shape of the conductor layer 300 .

[0016] Figure 7 It is a schematic plan view of the insulating layer 30 .

[0017] Figure 8 This is an equivalent circuit diagram of common mode filter 1.

[0018] Figure 9 is a schematic cross-sectional view of the common mode filter 1 .

[0019] Figure 10 This is a graph for explaining the effects of the first embodiment.

[0020] Figure 11 It is a schematic plan view for explaining the pattern shape of a conductor layer 100A used in a common mode filter according to a second embodiment of the technology according to the present invention.

[0021] Figure 12 1 is a schematic cross-sectional view of a common mode filter according to a second embodiment.

[0022] Figure 13 This is a schematic plan view for explaining the pattern shape of a conductor layer 100B used in a common mode filter according to a third embodiment of the technology according to the present invention.

[0023] Figure 14 It is a schematic plan view for explaining the pattern shape of a conductor layer 100C used in a common mode filter according to a fourth embodiment of the technology according to the present invention.

[0024] Figure 15 It is a schematic plan view for explaining the pattern shape of a conductor layer 300A used in the common mode filter according to the fifth embodiment.

[0025] Figure 16 It is a schematic plan view of the insulating layer 30 used in the common mode filter according to the fifth embodiment.

[0026] Figure 17 It is a schematic plan view for explaining the pattern shape of the conductive layer 400 .

[0027] Figure 18 It is a schematic top view of the insulating layer 40 .

[0028] Figure 19 1 is a schematic cross-sectional view of a common mode filter according to a fifth embodiment.

[0029] Explanation of symbols

[0030] 1 Common mode filter

[0031] 2 body

[0032] 10, 20, 30, 40 insulation layers

[0033] 11-15, 21-26, 31-34, 36, 41-44 openings

[0034] 100, 100A, 100B, 100C, 200, 300, 300A, 400 conductor layers

[0035] 110, 210, 310, 410 coil patterns

[0036] 111, 211, 311, 411 outermost circles

[0037] 112, 212, 312, 412 innermost circles

[0038] 113, 213 middle turns

[0039] 113a, 213a, 313a are the second turn from the outermost circle

[0040] 113b, 213b from the second turn of the innermost circle

[0041] 114, 214, 314, 325a, 326a, 414 lead-out parts

[0042] 115, 116, 315 spaces

[0043] 117, 118 virtual patterns

[0044] 121-125, 221-226, 321-326, 421-424, 426 connection patterns

[0045] C1, C2 capacitance components

[0046] E1~E4 terminal electrodes

[0047] S1 to S6 are non-overlapping intervals. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the technology according to the present invention will be described in detail with reference to the accompanying drawings.

[0049] <First embodiment>

[0050] Figure 1 It is a schematic perspective view showing the appearance of a common mode filter 1 according to a first embodiment of the technology according to the present invention.

[0051] The common mode filter 1 of the first embodiment is a surface mount chip component, such as Figure 1 As shown, the element body 2 is provided with four terminal electrodes E1 to E4 embedded in the element body 2. As will be described later, three conductive layers 100, 200, and 300 stacked with insulating layers interposed therebetween are embedded in the element body 2.

[0052] Figure 2 It is a schematic plan view for explaining the pattern shape of the conductive layer 100 .

[0053] The conductor layer 100 is the bottommost conductor layer and has a spiral coil pattern 110 and connection patterns 121 to 125. Figure 2 In the example shown, coil pattern 110 has approximately 12 turns, including an outermost turn 111, an innermost turn 112, and intermediate turns 113 located between the second-most turn 113a from the outermost and the second-most turn 113b from the innermost. Intermediate turns 113 have approximately 10 turns. The outer end of coil pattern 110 is connected to connection pattern 121 via lead portion 114. The inner end of coil pattern 110 is connected to connection pattern 125. While coil pattern 110 winds clockwise (clockwise) from the outer end to the inner end, lead portion 114 does not wind clockwise (clockwise) and extends linearly in the -X direction from the outer end to the inner end. Connection patterns 122-124 are independently provided within conductor layer 100, not connected to other conductor patterns.

[0054] Figure 3 It is a schematic plan view of the insulating layer 10 .

[0055] The insulating layer 10 is located between the conductive layer 100 and the conductive layer 200 and has openings 11 to 15. The openings 11 to 15 are provided at positions where the connection patterns 121 to 125 are exposed, respectively.

[0056] Figure 4 It is a schematic plan view for explaining the pattern shape of the conductive layer 200 .

[0057] The conductor layer 200 includes a spiral coil pattern 210 and connection patterns 221 to 226. Figure 4In the example shown, coil pattern 210 has approximately 12 turns, including outermost turns 211, innermost turns 212, and intermediate turns 213 located between the second-largest turn 213a and the second-largest turn 213b. Intermediate turns 213 have approximately 10 turns. In other words, the number of turns of coil pattern 110 and coil pattern 210 is approximately the same. Even if there is a difference in the number of turns between coil pattern 110 and coil pattern 210 due to factors such as the position of the lead portion, the difference in the number of turns between coil pattern 110 and coil pattern 210 must be less than 1 / 2 turn to ensure the function as a common mode filter.

[0058] The outer end of coil pattern 210 is connected to connection pattern 222 via lead portion 214. The inner end of coil pattern 210 is connected to connection pattern 226. While coil pattern 210 winds clockwise from the outer end toward the inner end, lead portion 214 extends linearly in the +X direction from the outer end toward the inner end. Connection patterns 221, 223, 224, and 225 are independently provided within conductor layer 200 without being connected to other conductor patterns. Connection patterns 221-225 are connected to connection patterns 121-125, respectively, via openings 11-15 provided in insulating layer 10.

[0059] Figure 5 It is a schematic top view of the insulating layer 20 .

[0060] The insulating layer 20 is located between the conductive layer 200 and the conductive layer 300 and has openings 21 to 26. The openings 21 to 26 are provided at positions where the connection patterns 221 to 226 are exposed, respectively.

[0061] Figure 6 It is a schematic plan view for explaining the pattern shape of the conductor layer 300 .

[0062] Conductive layer 300 includes connection patterns 321 to 326. Connection patterns 321 to 326 are connected to connection patterns 221 to 226, respectively, via openings 21 to 26 provided in insulating layer 20. Connection pattern 325 is connected to connection pattern 323 via lead portion 325a. Connection pattern 326 is connected to connection pattern 324 via lead portion 326a.

[0063] Figure 7 It is a schematic plan view of the insulating layer 30 .

[0064] The insulating layer 30 is the uppermost insulating layer and has openings 31 to 34. The openings 31 to 34 are provided at positions where the connection patterns 321 to 324 are exposed. Figure 1 The terminal electrodes E1 to E4 shown are connected to the connection patterns 321 to 324 via the openings 31 to 34 , respectively.

[0065] With this structure, the outer peripheral end of the coil pattern 110 is connected to the terminal electrode E1, the outer peripheral end of the coil pattern 210 is connected to the terminal electrode E2, the inner peripheral end of the coil pattern 110 is connected to the terminal electrode E3, and the inner peripheral end of the coil pattern 210 is connected to the terminal electrode E4. Figure 8 As shown, the coil pattern 110 connected between the terminal electrode E1 and the terminal electrode E3 and the coil pattern 210 connected between the terminal electrode E2 and the terminal electrode E4 are coupled.

[0066] In this embodiment, if Figure 2 As shown, the radial space between adjacent turns of the coil pattern 110 is not constant. The space 115 between the outermost turn 111 and the second turn 113a from the outermost circumference, and the space 116 between the innermost turn 112 and the second turn 113b from the innermost circumference are larger than the space between the turns constituting the intermediate turn 113. The spaces 115 and 116 are larger than the pattern width of the coil pattern 210. The radial space between the turns constituting the intermediate turn 113 is approximately constant. On the other hand, as Figure 4 As shown, the radial distance between adjacent turns of the coil pattern 210 is substantially constant.

[0067] Thus, as shown in the schematic cross-sectional view Figure 9 As shown, at least a portion of the outermost turn 111 of coil pattern 110 and the outermost turn 211 of coil pattern 210 do not overlap, and at least a portion of the innermost turn 112 of coil pattern 110 and the innermost turn 212 of coil pattern 210 do not overlap. The portion of the outermost turn 111 of coil pattern 110 that does not overlap with the outermost turn 211 of coil pattern 210 constitutes a non-overlapping section S1. The portion of the innermost turn 112 of coil pattern 110 that does not overlap with the innermost turn 212 of coil pattern 210 constitutes a non-overlapping section S2. The portion of the outermost turn 211 of coil pattern 210 that does not overlap with the outermost turn 111 of coil pattern 110 constitutes a non-overlapping section S4. The portion of the innermost turn 212 of coil pattern 210 that does not overlap with the innermost turn 112 of coil pattern 110 constitutes a non-overlapping section S5.

[0068] Thus, because the outermost turns 111 and 211 of the coil patterns 110 and 210 have non-overlapping sections S1 and S4, respectively, the inter-line capacitance generated between the outermost turns 111 and 211 is reduced, resulting in a reduction in the capacitance component C1 near the terminal electrodes E1 and E2. Similarly, because the innermost turns 112 and 212 of the coil patterns 110 and 210 have non-overlapping sections S2 and S5, respectively, the inter-line capacitance generated between the innermost turns 112 and 212 is reduced, resulting in a reduction in the capacitance component C2 near the terminal electrodes E3 and E4.

[0069] Each of the intermediate turns 113 constituting the coil pattern 110 overlaps with each of the intermediate turns 213 constituting the coil pattern 210. This improves the coupling between the coil pattern 110 and the coil pattern 210.

[0070] The non-overlapping section S1 of the coil pattern 110 can consist of the entire outermost turn 111 or a portion thereof. However, to achieve the effect of reducing the capacitance component C1, at least one-quarter of the outermost turn 111 must constitute the non-overlapping section S1, and preferably at least one-half of the outermost turn 111 must constitute the non-overlapping section S1. In other words, the non-overlapping section S1 of the coil pattern 110 does not refer to a section such as the outlet 114, but rather to a section that loops in the same direction from the second outermost turn 113a, and includes at least a portion extending in the X-direction and a portion extending in the Y-direction.

[0071] The same applies to the non-overlapping section S2 of the coil pattern 110. It can consist of the entire innermost turn 112 or a portion of it. However, to achieve the effect of reducing the capacitance component C2, at least one-quarter of the innermost turn 112 must constitute the non-overlapping section S2, and preferably at least one-half of the innermost turn 112 must constitute the non-overlapping section S2. In other words, the non-overlapping section S2 of the coil pattern 110 is a section that loops in the same direction from the second innermost turn 113b, and includes at least a portion extending in the X-direction and a portion extending in the Y-direction.

[0072] The lengths of the non-overlapping sections S1 and S2 can be adjusted using the calculated capacitance components C1 and C2. However, if the non-overlapping sections S1 and S2 each exceed one turn, the coupling between the coil pattern 110 and the coil pattern 210 decreases. Therefore, the lengths of the non-overlapping sections S1 and S2 are preferably one turn or less.

[0073] Figure 10 This is a graph for explaining the effects of the first embodiment, and is a simulation result showing the insertion loss (Sdd21) of the differential mode signal. Figure 10 In the figure, the solid line represents the characteristics of the common mode filter 1 according to the present embodiment, while the dashed line represents the characteristics of the common mode filter according to the comparative example, which has no non-overlapping sections except for lead portions 114 and 214 and their vicinities, and near the inner peripheral end. In other words, in the common mode filter according to the comparative example, the radial spacing between adjacent turns of coil pattern 110 is also substantially constant.

[0074] like Figure 10As shown, the common mode filter 1 of this embodiment has lower insertion loss for differential mode signals than the common mode filter of the comparative example. This is believed to be due to the reduction of capacitance components C1 and C2 near the terminal electrodes E1 to E4 by providing the non-overlapping sections.

[0075] In order to further reduce the capacitance components C1 and C2 , the pattern widths of the non-overlapping sections S1 , S2 , S4 , and S5 may be made smaller than the pattern widths of the turns constituting the intermediate turns 113 and 213 .

[0076] <Second embodiment>

[0077] Figure 11 This is a schematic plan view for explaining the pattern shape of the conductor layer 100A used in the common mode filter according to the second embodiment of the technology involved in the present invention. Figure 12 1 is a schematic cross-sectional view of a common mode filter according to a second embodiment.

[0078] like Figure 11 and Figure 12 As shown, the conductor layer 100A used in the common mode filter of the second embodiment differs from the conductor layer 100 described above in that dummy patterns 117 and 118 are added. The rest of the basic structure is the same as that of the common mode filter 1 of the first embodiment, so the same elements are denoted by the same reference numerals and duplicate descriptions are omitted.

[0079] The dummy pattern 117 is arranged between the non-overlapping section S1 of the outermost turn 111 and the second turn 113a from the outermost circumference and is not connected to the coil pattern 110 but is in a floating state. The dummy pattern 117 overlaps the non-overlapping section S4 of the outermost turn 211 of the coil pattern 210.

[0080] The dummy pattern 118 is arranged between the non-overlapping section S2 of the innermost turn 112 and the second turn 113b from the innermost circumference and is not connected to the coil pattern 110 but is in a floating state. The dummy pattern 118 overlaps the non-overlapping section S5 of the innermost turn 212 of the coil pattern 210.

[0081] Dummy patterns 117 and 118 serve as a foundation for forming the outermost turn 211 and innermost turn 212 of coil pattern 210. Providing such dummy patterns 117 and 118 can ease the process complexity of forming coil pattern 210. To provide dummy patterns 117 and 118, the pattern spacing between the non-overlapping section S1 of outermost turn 111 and the second turn 113a from the outermost circumference, and the pattern spacing between the non-overlapping section S2 of innermost turn 112 and the second turn 113b from the innermost circumference, can be designed to be at least twice the pattern spacing of the turns constituting intermediate turns 113.

[0082] <Third embodiment>

[0083] Figure 13 This is a schematic plan view for explaining the pattern shape of a conductor layer 100B used in a common mode filter according to a third embodiment of the technology according to the present invention.

[0084] like Figure 13 As shown, the conductor layer 100B used in the common mode filter of the third embodiment is different from the common mode filter in that the innermost turn 112 of the coil pattern 110 does not include the non-overlapping section S2. Figure 2 The conductor layer 100 shown is different. That is, the space between each turn except the outermost turn 111 of the coil pattern 110 is substantially constant. Since the other basic structures are the same as those of the common mode filter 1 of the first embodiment, the same reference numerals are used for the same elements, and repeated descriptions are omitted.

[0085] As exemplified in the third embodiment, the innermost turn 112 of the coil pattern 110 may not include the non-overlapping section S2 , and the outermost turn 111 of the coil pattern 110 may include the non-overlapping section S1 .

[0086] <Fourth embodiment>

[0087] Figure 14 It is a schematic plan view for explaining the pattern shape of a conductor layer 100C used in a common mode filter according to a fourth embodiment of the technology according to the present invention.

[0088] like Figure 14 As shown, the conductor layer 100C used in the common mode filter of the fourth embodiment is different from the common mode filter in that the outermost turn 111 of the coil pattern 110 does not include the non-overlapping section S1. Figure 2 The conductor layer 100 shown is different. That is, the space between each turn except the innermost turn 112 of the coil pattern 110 is substantially constant. Since the other basic structures are the same as those of the common mode filter 1 of the first embodiment, the same reference numerals are used for the same elements and repeated descriptions are omitted.

[0089] As exemplified in the fourth embodiment, the outermost turn 111 of the coil pattern 110 may not include the non-overlapping section S1 , and the innermost turn 112 of the coil pattern 110 may include the non-overlapping section S2 .

[0090] <Fifth embodiment>

[0091] The common mode filter of the fifth embodiment of the technology according to the present invention has a structure in which four conductor layers 100B, 200, 300A, and 400 are stacked with insulating layers interposed therebetween and embedded in the element body 2. The pattern shape of the conductor layer 100B is as follows: Figure 13 As shown, the pattern shape of the conductor layer 200 is as follows Figure 4 In addition, the shape of the insulating layer 10 between the conductor layer 100B and the conductor layer 200 is as shown in FIG. Figure 3 As shown, the shape of the insulating layer 20 located between the conductor layer 200 and the conductor layer 300A is as follows: Figure 5 shown.

[0092] Figure 15 It is a schematic plan view for explaining the pattern shape of a conductor layer 300A used in the common mode filter according to the fifth embodiment.

[0093] like Figure 15 As shown, the conductor layer 300A used in the common mode filter of the fifth embodiment includes a coil pattern 310, a connection pattern 323 connected to the outer peripheral end of the coil pattern 310, a connection pattern 325 connected to the inner peripheral end of the coil pattern 310, and a connection pattern 326 independently provided in the conductor layer 300A without being connected to other conductor patterns. Figure 6 The conductor layer 300 shown is different. The other basic structures are different from Figure 6 Since the conductor layer 300 shown is the same, the same elements are denoted by the same reference numerals and redundant descriptions are omitted.

[0094] exist Figure 15 In the example shown, coil pattern 310 has approximately 12 turns. The outer end of coil pattern 310 is connected to connection pattern 323 via lead portion 314. While coil pattern 310 winds counterclockwise (or counterclockwise) from the outer end toward the inner end, lead portion 314 does not wind counterclockwise (or counterclockwise) but extends linearly in the -X direction from the outer end toward the inner end. Connection patterns 321, 322, 324, and 326 are independently provided within conductor layer 300A, not connected to other conductor patterns.

[0095] Figure 16 It is a schematic plan view of the insulating layer 30 used in the common mode filter according to the fifth embodiment.

[0096] The insulating layer 30 is located between the conductive layer 300A and the conductive layer 400 and has an opening 36. Figure 7 The insulating layer 30 shown is different. The opening 36 is provided at a position where the connection pattern 326 is exposed. Figure 7 Since the insulating layer 30 shown is the same, the same elements are denoted by the same reference numerals and redundant descriptions are omitted.

[0097] Figure 17 It is a schematic plan view for explaining the pattern shape of the conductive layer 400 .

[0098] The conductor layer 400 includes a spiral coil pattern 410 and connection patterns 421 to 424 and 426. Figure 17 In the example shown, the number of turns of the coil pattern 410 is approximately 12. That is, the number of turns of the coil pattern 310 and the number of turns of the coil pattern 410 are approximately the same. The outer peripheral end of the coil pattern 410 is connected to the connection pattern 424 via the lead portion 414. The inner peripheral end of the coil pattern 410 is connected to the connection pattern 426. The coil pattern 410 is wound counterclockwise (counterclockwise) from the outer peripheral end to the inner peripheral end, while the lead portion 414 extends linearly in the +X direction from the outer peripheral end to the inner peripheral end. The connection patterns 421 to 423 are independently provided in the conductor layer 400 without being connected to other conductor patterns. The connection patterns 421 to 424 and 426 are connected to the connection patterns 321 to 324 and 326 respectively via the openings 31 to 34 and 36 provided in the insulating layer 30.

[0099] Figure 18 It is a schematic top view of the insulating layer 40 .

[0100] The insulating layer 40 is the uppermost insulating layer and has openings 41 to 44. The openings 41 to 44 are provided at positions where the connection patterns 421 to 424 are exposed. Figure 1 The terminal electrodes E1 to E4 shown are connected to the connection patterns 421 to 424 via the openings 41 to 44 , respectively.

[0101] With this structure, the outer end of coil pattern 110 is connected to terminal electrode E1, the outer end of coil pattern 210 is connected to terminal electrode E2, the outer end of coil pattern 310 is connected to terminal electrode E3, and the outer end of coil pattern 410 is connected to terminal electrode E4. Furthermore, the inner ends of coil pattern 110 and coil pattern 310 are connected to each other, and the inner ends of coil pattern 210 and coil pattern 410 are connected to each other. Thus, coil patterns 110 and 310 connected between terminal electrode E1 and terminal electrode E3 are coupled to coil patterns 210 and 410 connected between terminal electrode E2 and terminal electrode E4.

[0102] In this embodiment, if Figure 15 As shown, the radial spacing between adjacent turns of coil pattern 310 is not constant. Space 315 between the outermost turn 311 and the second turn 313a from the outermost is wider than the spaces between other turns. Space 315 is larger than the pattern width of coil pattern 410. Space 315 may also be larger than the pattern width of coil pattern 210. The radial spacing between turns of coil pattern 310 other than outermost turn 311 is substantially constant.

[0103] Thus, as shown in the schematic cross-sectional view Figure 19As shown, at least a portion of the outermost turns 311 of coil pattern 310 and the outermost turns 411 of coil pattern 410 do not overlap. The portion of outermost turns 311 of coil pattern 310 that does not overlap with the outermost turns 411 of coil pattern 410 constitutes a non-overlapping section S3. Non-overlapping section S3 may also not overlap with the outermost turns 211 of coil pattern 210. The portion of outermost turns 411 of coil pattern 410 that does not overlap with the outermost turns 311 of coil pattern 310 constitutes a non-overlapping section S6.

[0104] Because the outermost turns 111, 211, 311, and 411 of coil patterns 110, 210, 310, and 410 have non-overlapping sections S1, S4, S3, and S6, respectively, the interline capacitance generated between the outermost turns 111 and 211, as well as the interline capacitance generated between the outermost turns 311 and 411, is reduced. As a result, the capacitance component C1 near the terminal electrodes E1 and E2 is reduced, and the capacitance component C2 near the terminal electrodes E3 and E4 is reduced. Furthermore, when the non-overlapping section S3 does not overlap with the outermost turn 211 of coil pattern 210, the interline capacitance generated between the outermost turns 211 and 311 is also reduced.

[0105] On the other hand, the turns other than the outermost turns 111, 211, 311, and 411 of the coil patterns 110, 210, 310, and 410 overlap with each other, thereby improving the coupling between the coil patterns 110, 310 and 210, 410.

[0106] Alternatively, as exemplified in the fifth embodiment, four coil patterns 110, 210, 310, and 410 may be stacked in sequence, with the inner circumferential end of coil pattern 110 connected to the inner circumferential end of coil pattern 310, and the inner circumferential end of coil pattern 210 connected to the inner circumferential end of coil pattern 410. In this manner, since the terminal electrodes E1 to E4 are connected to the outermost turns 111, 211, 311, and 411 of the coil patterns 110, 210, 310, and 410, respectively, the difference in characteristics between when terminal electrodes E1 and E2 are positioned on the input side and terminal electrodes E3 and E4 are positioned on the output side and when terminal electrodes E1 and E2 are positioned on the output side and terminal electrodes E3 and E4 are positioned on the input side is reduced.

[0107] The above describes the implementation methods of the technology involved in the present invention, but the technology involved in the present invention is not limited to the above implementation methods. Various changes can be made without departing from the scope of the present invention, and they are of course included in the scope of the technology involved in the present invention.

[0108] The technology according to the present invention includes the following configuration examples, but is not limited thereto.

[0109] A common mode filter according to one aspect of the present invention comprises: a plurality of conductor layers stacked with an insulating layer interposed therebetween, including at least first and second conductor layers; and first, second, third, and fourth terminal electrodes. The first conductor layer comprises a first spiral coil pattern with its outer end connected to the first terminal electrode and its inner end connected to the third terminal electrode. The second conductor layer comprises a second spiral coil pattern with its outer end connected to the second terminal electrode and its inner end connected to the fourth terminal electrode. The outermost turn of the first coil pattern has a first non-overlapping section that does not overlap with the outermost turn of the second coil pattern over at least a quarter of its turn, or the innermost turn of the first coil pattern has a second non-overlapping section that does not overlap with the innermost turn of the second coil pattern over at least a quarter of its turn. This reduces inter-line capacitance near the first and second terminal electrodes, or near the third and fourth terminal electrodes.

[0110] In the common mode filter described above, the first coil pattern may have both a first non-overlapping section and a second non-overlapping section. This can reduce both line capacitance near the first and second terminal electrodes and line capacitance near the third and fourth terminal electrodes.

[0111] In the common mode filter described above, the plurality of conductor layers may further include third and fourth conductor layers, wherein the first, second, third, and fourth conductor layers are stacked in sequence with an insulating layer interposed therebetween, the third conductor layer including a spiral third coil pattern having an outer peripheral end connected to the third terminal electrode and an inner peripheral end connected to the inner peripheral end of the first coil pattern, the fourth conductor layer including a spiral fourth coil pattern having an outer peripheral end connected to the fourth terminal electrode and an inner peripheral end connected to the inner peripheral end of the second coil pattern, the outermost turn of the first coil pattern including a first non-overlapping section, and the outermost turn of the third coil pattern including a third non-overlapping section that surrounds the outermost turn of the fourth coil pattern without overlapping with the outermost turn of the fourth coil pattern over at least a quarter of a turn. Thus, the difference between the characteristics when the first and second terminal electrodes are positioned on the input side and the third and fourth terminal electrodes are positioned on the output side and the characteristics when the first and second terminal electrodes are positioned on the output side and the third and fourth terminal electrodes are positioned on the input side is reduced.

[0112] In the common mode filter described above, the first radial space between the first non-overlapping section of the first coil pattern and the second turn from the outermost circumference, or the second radial space between the second non-overlapping section of the first coil pattern and the second turn from the innermost circumference, may be wider than the radial space between the turns constituting the intermediate turn between the second turn from the outermost circumference and the second turn from the innermost circumference of the first coil pattern. This allows the radial dimension of the first coil pattern to be miniaturized.

[0113] In the common mode filter described above, at least one of the first and second spaces may be larger than a pattern width of the second coil pattern. This allows the second coil pattern to be arranged at a position overlapping at least one of the first and second spaces.

[0114] In the common mode filter described above, the pattern pitch between the first non-overlapping section and the middle turn, or the pattern pitch between the second non-overlapping section and the middle turn, may be at least twice the pattern pitch of the turns constituting the middle turn. This allows for the placement of a dummy pattern in at least one of the first and second spaces.

[0115] In the common mode filter described above, the first conductor layer may further include a first dummy pattern arranged in the first space or a second dummy pattern arranged in the second space. This facilitates formation of the second coil pattern.

[0116] In the common mode filter described above, the pattern width of the first or second non-overlapping section may be smaller than the pattern width of each turn constituting the intermediate turn. This can further reduce the inter-line capacitance near the first and second terminal electrodes, or the inter-line capacitance near the third and fourth terminal electrodes.

[0117] In the common mode filter described above, each of the turns constituting the intermediate turns may overlap with the second coil pattern, thereby improving coupling between the first coil pattern and the second coil pattern.

Claims

1. A common mode filter, wherein: have: a plurality of conductor layers stacked with insulating layers interposed therebetween, and including at least first and second conductor layers; and first, second, third and fourth terminal electrodes, The first conductor layer includes a spiral first coil pattern whose outer peripheral end is connected to the first terminal electrode and whose inner peripheral end is connected to the third terminal electrode. The second conductor layer includes a spiral second coil pattern whose outer peripheral end is connected to the second terminal electrode and whose inner peripheral end is connected to the fourth terminal electrode. The outermost turn of the first coil pattern has a first non-overlapping interval that surrounds at least 1 / 4 of the turn without overlapping with the outermost turn of the second coil pattern, or the innermost turn of the first coil pattern has a second non-overlapping interval that surrounds at least 1 / 4 of the turn without overlapping with the innermost turn of the second coil pattern.

2. The common mode filter according to claim 1, wherein The first coil pattern includes both the first non-overlapping section and the second non-overlapping section.

3. The common mode filter according to claim 1, wherein The plurality of conductor layers further include a third and a fourth conductor layer, The first, second, third and fourth conductor layers are stacked in sequence with the insulating layer interposed therebetween. The third conductor layer includes a spiral third coil pattern whose outer peripheral end is connected to the third terminal electrode and whose inner peripheral end is connected to the inner peripheral end of the first coil pattern. The fourth conductor layer includes a spiral fourth coil pattern whose outer peripheral end is connected to the fourth terminal electrode and whose inner peripheral end is connected to the inner peripheral end of the second coil pattern. The outermost turns of the first coil pattern have the first non-overlapping section, The outermost turn of the third coil pattern has a third non-overlapping section that surrounds the outermost turn of the fourth coil pattern over at least 1 / 4 of the turn without overlapping with the outermost turn of the fourth coil pattern.

4. The common mode filter according to claim 1, wherein The first non-overlapping interval of the first coil pattern and the first radial space between the second turn from the outermost circumference, or the second non-overlapping interval of the first coil pattern and the second radial space between the second turn from the innermost circumference, is wider than the radial space between each turn located from the second turn from the outermost circumference to the middle turn from the second turn from the innermost circumference of the first coil pattern.

5. The common mode filter according to claim 4, wherein At least one of the first and second spaces is larger than a pattern width of the second coil pattern. The common mode filter according to claim 5 , wherein: A pattern pitch between the first non-overlapping section and the middle turn, or a pattern pitch between the second non-overlapping section and the middle turn, is at least twice a pattern pitch between turns constituting the middle turn.

7. The common mode filter according to claim 6, wherein: The first conductive layer further includes a first dummy pattern arranged in the first space, or a second dummy pattern arranged in the second space.

8. The common mode filter according to claim 4, wherein The pattern width of the first or second non-overlapping interval is smaller than the pattern width of each turn constituting the middle turn.

9. The common mode filter according to any one of claims 4 to 8, wherein Each of the turns constituting the intermediate turn overlaps with the second coil pattern.

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