Isolator

Abstract

To provide an isolator that can improve dielectric strength.SOLUTION: An isolator according to an embodiment includes a first wiring board 31 and a second wiring board 32. The first wiring board 31 includes an insulating layer 53 having a first main surface and a second main surface opposite to the first main surface, a first coil 311 provided on the first main surface, and a pad 312a provided on the first main surface and electrically connected to the first coil 311. The second wiring board 32 includes an insulating layer 63 having a third main surface and a fourth main surface opposite to the third main surface, a second coil 321 provided on the third main surface, and a pad 322a that is provided on the fourth main surface, and electrically connected to the second coil 321. The first coil 311 and the second coil 321 are arranged to face each other, and the outer size of the second wiring board 32 is smaller than the outer size of the first wiring board 31.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to an isolator. [Background technology]

[0002] 2. Description of the Related Art An isolator is known that transmits a signal from a transmitting circuit to a receiving circuit while isolating the transmitting circuit from the receiving circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 9,035,422 Summary of the Invention [Problem to be solved by the invention]

[0004] An isolator capable of improving dielectric strength voltage is provided. [Means for solving the problem]

[0005] The isolator of the embodiment comprises a first wiring board and a second wiring board. The first wiring board comprises a first insulating layer having a first main surface and a second main surface opposite the first main surface, a first coil provided on the first main surface, and a first pad provided on the first main surface and electrically connected to the first coil. The second wiring board comprises a second insulating layer having a third main surface and a fourth main surface opposite the third main surface, a second coil provided on the third main surface, and a second pad provided on the fourth main surface and electrically connected to the second coil. The first coil and the second coil are arranged to face each other, and the outer size of the second wiring board is At least in the first direction in which the second pad is pulled out The first coil is wound spirally along the first main surface. Two conductor A structure in which the first wiring board is provided on the second main surface and is arranged along the second main surface The aforementionedThe first wiring layer extends in a first direction. The first wiring layer includes a spirally wound wiring including the first coil. Two Conductor Each One end of the conductor in the center Each The first pad and Through vias The second coil is wound spirally along the third main surface. Two including the structure to which the conductor is connected. nothing . [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a plan view showing an isolator according to an embodiment. [Figure 2] FIG. 2 is a side view showing the isolator according to the embodiment. [Figure 3] FIG. 2 is a plan view of a wiring board in the isolator according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along the line AA in FIG. [Figure 5] FIG. 2 is a plan view of a first wiring board included in the wiring board according to the embodiment. [Figure 6] FIG. 2 is a plan view of a second wiring board included in the wiring board according to the embodiment. [Figure 7] 2 is a plan view of a first and second wiring board and a wiring board formed by bonding these together in the embodiment. FIG. [Figure 8] FIG. 10 is a diagram showing an example of a structure to be compared with the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments will be described with reference to the drawings. In the following description, components having the same function and configuration will be assigned the same reference numerals. Furthermore, the embodiments shown below are merely examples of devices and methods for embodying the technical ideas of the embodiments, and do not specify the materials, shapes, structures, arrangements, etc. of the components as described below.

[0008] An isolator according to an embodiment will be described. In the embodiment, an isolator having a structure in which a transformer for transmitting a signal is formed on a printed wiring board (or printed circuit board) will be described. The isolator transmits a signal by utilizing changes in a magnetic field (or magnetic signal) while insulating between a transmitting circuit (or primary circuit) and a receiving circuit (or secondary circuit).

[0009] 1 and 2 are a plan view and a side view, respectively, of an isolator according to an embodiment of the present invention.

[0010] As shown in FIGS. 1 and 2, the isolator 1 includes a semiconductor chip 10, a semiconductor chip 20, and a printed wiring board 30. The semiconductor chip 10 includes a first circuit 11 formed on a semiconductor substrate. The first circuit 11 includes, for example, a transmitting / receiving circuit and a modulation / demodulation circuit. The semiconductor chip 20 includes a second circuit 21 formed on the semiconductor substrate. The second circuit 21 includes, for example, a transmitting / receiving circuit and a modulation / demodulation circuit. The printed wiring board 30 is formed, for example, by a flexible printed wiring board (FPC: Flexible Printed Circuits). For example, the isolator 1 is formed by a semiconductor package in which the semiconductor chip 10, the semiconductor chip 20, and the wiring board 30 are sealed with resin (not shown). Hereinafter, a printed wiring board formed from this flexible printed wiring board will be simply referred to as a wiring board. Details of the wiring board 30 will be described later.

[0011] The semiconductor chip 10 is fixed onto the die pad 12 with an insulating adhesive 13. The semiconductor chip 20 is fixed onto the die pad 22 with an insulating adhesive 23. The wiring board 30 is provided on the semiconductor chip 10 and the semiconductor chip 20.

[0012] Bonding wires 14 are provided between the semiconductor chip 10 and the wiring board 30. The first circuit 11 of the semiconductor chip 10 and the wiring board 30 are electrically connected by the bonding wires 14. The bonding wires 24 are provided between the semiconductor chip 20 and the wiring board 30. The second circuit 21 of the semiconductor chip 20 and the wiring board 30 are electrically connected by the bonding wires 24.

[0013] A bonding wire 16 is provided between the semiconductor chip 10 and the lead frame 15. The first circuit 11 of the semiconductor chip 10 is electrically connected to the lead frame 15 by the bonding wire 16. Furthermore, a bonding wire 26 is provided between the semiconductor chip 20 and the lead frame 25. The second circuit 21 of the semiconductor chip 20 is electrically connected to the lead frame 25 by the bonding wire 26.

[0014] The wiring board 30 in the isolator 1 will be described below.

[0015] Fig. 3 is a plan view showing wiring board 30 in an isolator according to an embodiment. Fig. 4 is a cross-sectional view taken along line AA in Fig. 3, illustrating the cross-sectional structure of wiring board 30. In Figs. 3 and 4, two directions that are orthogonal to each other and parallel to the top surface of wiring board 30 are defined as the X direction and the Y direction, and the direction orthogonal to these X direction and Y direction (XY plane), i.e., the direction in which conductor layers and insulating layers are stacked in wiring board 30, is defined as the Z direction (or stacking direction).

[0016] 3 and 4, wiring board 30 has first wiring board 31, second wiring board 32, and insulating layer (e.g., silicon paste material) 33. First wiring board 31 is made of a flexible wiring board having flexibility. Second wiring board 32 is also made of a flexible wiring board having flexibility.

[0017] Second wiring board 32 is provided on first wiring board 31 with insulating layer 33 interposed therebetween. First wiring board 31 and second wiring board 32 are fixed together by insulating layer 33. In addition, the outer size of second wiring board 32 in the X direction is smaller than the outer size of first wiring board 31. Furthermore, the outer size of second wiring board 32 in the Y direction is smaller than the outer size of first wiring board 31. In other words, the length of second wiring board 32 in the X direction is shorter than the length of first wiring board 31. Furthermore, the length of second wiring board 32 in the Y direction is shorter than the length of first wiring board 31. The cross-sectional structures of first wiring board 31 and second wiring board 32 will be described later.

[0018] 5 and 6 are plan views of first wiring board 31 and second wiring board 32, respectively, which are views seen through the insulating layers.

[0019] 5 includes a first coil 311, pads (or terminals) 312a and 312b, and wiring layers 313a and 313b. Pad 312a is electrically connected to first coil 311 via wiring layer 313a. Furthermore, first coil 311 is electrically connected to pad 312b via wiring layer 313b.

[0020] The first coil 311 includes two conductors (hereinafter referred to as "spiral conductors") wound spirally along the XY plane. The two spiral conductors included in the first coil 311 have a predetermined inductance. The two spiral conductors are connected to each other at one end of their outer peripheries. One end of the central portion of one spiral conductor is electrically connected to the pad 312a via the wiring layer 313a. Furthermore, one end of the central portion of the other spiral conductor is electrically connected to the pad 312b via the wiring layer 313b.

[0021] 6 includes a second coil 321, pads (or terminals) 322a and 322b, and wiring layers 323a and 323b. Pad 322a is electrically connected to second coil 321 via wiring layer 323a. Furthermore, second coil 321 is electrically connected to pad 322b via wiring layer 323b.

[0022] The second coil 321 includes two spiral conductors wound spirally along the XY plane. The two spiral conductors included in the second coil 321 have a predetermined inductance. The two spiral conductors are connected to each other at one end of their outer peripheries. One end of the central portion of one spiral conductor is electrically connected to pad 322a via wiring layer 323a. Furthermore, one end of the central portion of the other spiral conductor is electrically connected to pad 322b via wiring layer 323b.

[0023] As shown in FIG. 7, first wiring board 31 and second wiring board 32 are bonded together to form wiring board 30.

[0024] The cross-sectional structure of wiring board 30 will be described below with reference to Fig. 4. As described above, second wiring board 32 is provided on first wiring board 31 with insulating layer 33 interposed therebetween.

[0025] First, the structure of first wiring board 31 will be described. First wiring board 31 has a multilayer wiring structure (or a double-sided wiring structure) with two conductor layers. That is, first wiring board 31 has insulating layer 51, adhesive 52, a first conductor layer including wiring layer 313a (and 313b), insulating layer 53, a second conductor layer including first coil 311 and pad 312a (and 312b), adhesive 54, and insulating layer 55. The first conductor layer includes wiring layer 313a (and 313b). The second conductor layer includes first coil 311 and pad 312a (and 312b).

[0026] The insulating layer 51, adhesive 52, wiring layer 313a, insulating layer 53, first coil 311 and pad 312a, adhesive 54, and insulating layer 55 are stacked in this order in the Z direction. More specifically, the wiring layer 313a is provided on the insulating layer 51. The insulating layer 53 is provided on the wiring layer 313a. That is, the wiring layer 313a is disposed between the insulating layer 51 and the insulating layer 53, and the insulating layer 53 and the insulating layer 51, and the wiring layer 313a and the insulating layer 51 are fixed together with the adhesive 52.

[0027] The first coil 311 and the pad 312a are provided on the insulating layer 53. The insulating layer 55 is provided on the first coil 311. The insulating layer 55 on the pad 312a is removed, leaving an opening above the pad 312a. That is, the first coil 311 and the pad 312a are disposed between the insulating layer 53 and the insulating layer 55, and the insulating layer 53 and the insulating layer 55, and the first coil 311 and the insulating layer 55 are fixed together with the adhesive 54.

[0028] The first coil 311 includes, for example, copper. The thickness of the first coil 311 is, for example, 6 μm to 12 μm (not less than 6 μm and not more than 12 μm). The first coil 311 is formed of, for example, copper foil fixed to the insulating layer 53.

[0029] The wiring layer 313a extends in the X direction from the center of the spirally wound first coil 311 to the pad 312a. The wiring layer 313a has a conductor layer 313aa and a conductor layer 313ab stacked in the Z direction. For example, the conductor layers 313aa and 313ab contain copper. The conductor layer 313aa is formed of copper foil adhered to the insulating layer 53, and the conductor layer 313ab is formed by plating. A via 313ac penetrating the insulating layer 53 is provided between the first coil 311 and the wiring layer 313a.

[0030] The pad 312a has a conductor layer 312aa and a conductor layer 312ab stacked in the Z direction. For example, the conductor layer 312aa contains copper. The conductor layer 312ab contains stacked nickel, palladium, and gold. The conductor layer 312aa is formed of copper foil adhered to the insulating layer 53, and the conductor layer 312ab is formed by plating. A via 312ac penetrating the insulating layer 53 is provided between the pad 312a and the wiring layer 313a.

[0031] The conductor layer 313ab, the via 312ac, and the via 313ac are formed by plating in the same process, for example, and are integrated together, so that the pad 312a is electrically connected to the first coil 311 through the via 312ac, the wiring layer 313a, and the via 313ac.

[0032] The insulating layers 51, 53, and 55 contain, for example, polyimide or a polyimide compound. The thickness of the insulating layer 51 is, for example, 6 μm to 25 μm (not less than 6 μm and not more than 25 μm). The thickness of the insulating layer 53 is, for example, 6 μm to 25 μm (not less than 6 μm and not more than 25 μm). The thickness of the insulating layer 55 is, for example, 6 μm to 25 μm (not less than 6 μm and not more than 25 μm).

[0033] Next, the structure of second wiring board 32 will be described. Like first wiring board 31, second wiring board 32 has a multilayer wiring structure (or double-sided wiring structure) with two conductor layers. That is, second wiring board 32 has insulating layer 61, adhesive 62, a third conductor layer, insulating layer 63, a fourth conductor layer, pads 322a (and 322b), adhesive 64, and insulating layer 65. The third conductor layer includes second coil 321. The fourth conductor layer includes wiring layer 323a (and 323b).

[0034] The insulating layer 61, adhesive 62, second coil 321, insulating layer 63, wiring layer 323a, adhesive 64, and insulating layer 65 are stacked in this order in the Z direction. More specifically, the second coil 321 is provided on the insulating layer 61. The insulating layer 63 is provided on the second coil 321. That is, the second coil 321 is disposed between the insulating layer 61 and the insulating layer 63, and the insulating layer 63 and the insulating layer 61, and the second coil 321 and the insulating layer 61 are fixed together with the adhesive 62.

[0035] A wiring layer 323a is provided on the insulating layer 63. An insulating layer 65 is provided on the wiring layer 323a. A pad 322a is also provided on the wiring layer 323a. The insulating layer 65 on the pad 322a is removed, leaving an opening above the pad 322a. That is, the wiring layer 323a is disposed between the insulating layer 63 and the insulating layer 65, and the insulating layer 63 and the insulating layer 65, and the wiring layer 323a and the insulating layer 65 are fixed together with an adhesive 64.

[0036] The second coil 321 includes, for example, copper. The thickness of the second coil 321 is, for example, 6 μm to 12 μm (6 μm or more and 12 μm or less). The second coil 321 is formed of, for example, copper foil fixed to the insulating layer 63.

[0037] The wiring layer 323a extends in the X direction from the center of the spirally wound second coil 321 to the pad 322a. The wiring layer 323a has a conductor layer 323aa and a conductor layer 323ab stacked in the Z direction. For example, the conductor layers 323aa and 323ab contain copper. The conductor layer 323aa is formed of copper foil adhered to the insulating layer 63, and the conductor layer 323ab is formed by plating. A via 323ac penetrating the insulating layer 63 is provided between the second coil 321 and the wiring layer 323a.

[0038] The pad 322a includes a conductive layer, such as nickel, palladium, and gold, which are stacked together, and is formed by plating, for example.

[0039] The conductor layer 323ab and the via 323ac are formed by, for example, plating in the same process and are integrated together, so that the pad 322a is electrically connected to the second coil 321 via the wiring layer 323a and the via 323ac.

[0040] The insulating layers 61, 63, and 65 contain, for example, polyimide or a polyimide compound. The thickness of the insulating layer 61 is, for example, 6 μm to 25 μm (not less than 6 μm and not more than 25 μm). The thickness of the insulating layer 63 is, for example, 6 μm to 25 μm (not less than 6 μm and not more than 25 μm). The thickness of the insulating layer 65 is, for example, 6 μm to 25 μm (not less than 6 μm and not more than 25 μm).

[0041] 4, first coil 311 of first wiring board 31 and second coil 321 of second wiring board 32 are arranged to face each other. Insulating layers 55, 33, and 61 are arranged between first coil 311 and second coil 321. The thickness of insulating layers 55, 33, and 61 between first coil 311 and second coil 321 is, for example, 13 μm to 80 μm (13 μm or more and 80 μm or less). This ensures sufficient insulation between first coil 311 and second coil 321.

[0042] For example, first coil 311 is a primary coil, second coil 321 is a secondary coil, and these first coil 311 and second coil 321 form a transformer. An induced electromotive force is generated in second coil 321 by a current flowing through first coil 311, and a current flows through second coil 321. As a result, a current corresponding to the current flowing through first coil 311 can be generated in second coil 321 while maintaining an insulating state between first coil 311 and second coil 321.

[0043] The configuration of the embodiment can also be expressed as follows.

[0044] The isolator of this embodiment includes a first wiring board 31 and a second wiring board 32. First wiring board 31 includes an insulating layer 53 having a first main surface and a second main surface opposite the first main surface, a first coil 311 provided on the first main surface, and a pad 312a provided on the first main surface and electrically connected to first coil 311. Second wiring board 32 includes an insulating layer 63 having a third main surface and a fourth main surface opposite the third main surface, a second coil 321 provided on the third main surface, and a pad 322a provided on the fourth main surface and electrically connected to second coil 321. First coil 311 and second coil 321 are arranged to face each other, and the outer size of second wiring board 32 is smaller than the outer size of first wiring board 31.

[0045] Pad 312a of first wiring board 31 is disposed at a height between first coil 311 and second coil 321.

[0046] The distance from the first main surface of the insulating layer 53 to the pad 312a is shorter than the distance from the first main surface of the insulating layer 53 to the pad 322a.

[0047] The first main surface of the insulating layer 53 has a region that does not overlap with the third main surface of the insulating layer 63, and the pad 312a is disposed in this region.

[0048] First wiring board 31 has wiring layer 313a provided on the second main surface, and pad 312a is electrically connected to first coil 311 via wiring layer 313a. Second wiring board 32 has wiring layer 323a provided on the fourth main surface, and pad 322a is electrically connected to second coil 321 via wiring layer 323a.

[0049] First wiring board 31 is provided in insulating layer 53 and has via 313ac connecting first coil 311 and wiring layer 313a, and via 312ac provided in insulating layer 53 and connecting pad 312a and wiring layer 313a. Second wiring board 32 is provided in insulating layer 63 and has via 323ac connecting second coil 321 and wiring layer 323a.

[0050] First wiring board 31 includes insulating layers 51 and 55 sandwiching first coil 311 and wiring layer 313a, and second wiring board 32 includes insulating layers 61 and 65 sandwiching second coil 321 and wiring layer 323a.

[0051] The operation of the isolator 1 of this embodiment will be described. Here, the operation will be described, for example, from when an electrical signal is transmitted from the first circuit 11 of the semiconductor chip 10 to the second circuit 21 of the semiconductor chip 20 via the first coil 311 and the second coil 321 of the wiring board 30. In this case, the first circuit 11 functions as a transmitting circuit and a modulating circuit, and the second circuit 21 functions as a receiving circuit and a demodulating circuit.

[0052] First, the modulation circuit included in the first circuit 11 of the semiconductor chip 10 receives a first signal as an electrical signal from a circuit connected to the input stage. The modulation circuit modulates the first signal and converts it into a second signal, and outputs the second signal to the transmission circuit of the first circuit 11. The transmission circuit transmits the second signal to the first coil 311 via the bonding wire 14 and the wiring layer 313a. The first coil 311 converts the received second signal into a third signal as a magnetic signal.

[0053] The third signal is converted into a fourth signal as an electrical signal by the second coil 321. The fourth signal is received by a receiving circuit included in the second circuit 21 of the semiconductor chip 20 via the wiring layer 323a and the bonding wire 24. The receiving circuit outputs the received fourth signal to a demodulation circuit of the second circuit 21. The demodulation circuit demodulates the fourth signal and converts it into a fifth signal, and outputs the fifth signal to a circuit connected to the output stage of the second circuit 21. This fifth signal is a signal corresponding to the first signal before it was modulated by the modulation circuit of the first circuit 11.

[0054] As a result, with the first circuit 11 of the semiconductor chip 10 and the second circuit 21 of the semiconductor chip 20 insulated from each other, an electrical signal sent from the first circuit 11 of the semiconductor chip 10 is transmitted to the second circuit 21 of the semiconductor chip 20 via the first coil 311 and the second coil 321 of the wiring board 30.

[0055] According to this embodiment, an isolator capable of improving the dielectric strength voltage can be provided.

[0056] The effects of this embodiment will be described below. Fig. 8 shows an example of a structure to be compared with this embodiment. For example, when a transformer is formed using wiring board 100 with a four-layer structure having four conductor layers, the first conductor layer L1 is the lead-out wiring W1, the second conductor layer L2 is the first coil C1, the third conductor layer L3 is the second coil C2, and the fourth conductor layer L4 is the lead-out wiring W2.

[0057] In such a structure, when pads P1 and P2 for connecting wiring board 100 to a semiconductor chip or another wiring board are provided on wiring board 100, it is desirable to provide pads P1 and P2 on the same surface layer, for example, the fourth conductor layer L4, for ease of assembly. In this case, a through via PV is provided to connect lead-out wiring W1 on conductor layer L1 to pad P2 on conductor layer L4. In a wiring board having such a structure, if the second coil C2 and the through via PV are close to each other, insulation between the second coil C2 and the through via PV cannot be maintained, and discharge may occur.

[0058] In contrast, according to the configuration of this embodiment, a via is provided to connect the first conductor layer with the second conductor layer, and a via is provided to connect the third conductor layer with the fourth conductor layer, but a through via is not provided to connect the first conductor layer with the fourth conductor layer, so there is no problem with the dielectric strength voltage between the coil and the through via. This makes it possible to improve the dielectric strength voltage between the transmitting circuit and the receiving circuit. Therefore, the embodiment can provide an isolator that can improve the dielectric strength voltage.

[0059] According to the configuration of this embodiment, by not providing a through via extending from the first conductor layer to the fourth conductor layer, it is possible to reduce the weakness of the withstand voltage in the X direction (or the extension direction of wiring layer 313a), which in turn makes it possible to shorten the length of wiring board 30 in the X direction, thereby enabling miniaturization of wiring board 30.

[0060] Furthermore, according to the configuration of this embodiment, a wiring board 30 having first coil 311 and second coil 321 is formed using two-layer wiring boards 31 and 32 each having two conductor layers, rather than using a four-layer wiring board having four conductor layers. Because a two-layer wiring board has a simpler structure and manufacturing process than a four-layer wiring board, design rules are relaxed and the lines and spaces of the wiring layers can be reduced. This allows for a more compact wiring board 30. Furthermore, the degree of freedom in designing the wiring board 30 is improved.

[0061] As described above, according to this embodiment, it is possible to provide an isolator that can improve the withstand voltage between the transmitting circuit and the receiving circuit, and further, it is possible to reduce the size of the isolator.

[0062] In the above-described embodiment, an example was described in which a flexible printed wiring board formed from a flexible substrate was used as a wiring board having a transformer, but it is not limited to a flexible printed wiring board, and a rigid printed wiring board formed from a hard substrate can also be used.

[0063] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Explanation of symbols]

[0064] 1...isolator, 10...semiconductor chip, 11...first circuit, 12...die pad, 13...adhesive, 14...bonding wire, 15...lead frame, 16...bonding wire, 20...semiconductor chip, 21...second circuit, 22...die pad, 23...adhesive, 24...bonding wire, 25...lead frame, 26...bonding wire, 30...printed wiring board, 31...first wiring board, 32...second wiring board, 33...insulating layer, 51...insulating layer, 52...adhesive, 53...insulating layer, 54...adhesive, 55... Insulating layer, 61...insulating layer, 62...adhesive, 63...insulating layer, 64...adhesive, 65...insulating layer, 311...first coil, 312a...pad, 312aa...conductor layer, 312ab...conductor layer, 312ac...via, 312b...pad, 313a...wiring layer, 313aa...conductor layer, 313ab...conductor layer, 313ac...via, 313b...wiring layer, 321...second coil, 322a...pad, 322b...pad, 323a...wiring layer, 323aa...conductor layer, 323ab...conductor layer, 323ac...via, 323b...wiring layer.

Claims

1. a first wiring board including a first insulating layer having a first main surface and a second main surface opposite to the first main surface, a first coil provided on the first main surface, and a first pad provided on the first main surface and electrically connected to the first coil; a second wiring board including a second insulating layer having a third main surface and a fourth main surface opposite to the third main surface, a second coil provided on the third main surface, and a second pad provided on the fourth main surface and electrically connected to the second coil; Equipped with The first coil and the second coil are arranged to face each other, an outer size of the second wiring board is smaller than an outer size of the first wiring board at least in a first direction in which the second pads are drawn out; the first coil includes a structure in which two conductors wound in a spiral shape along the first main surface are connected to each other, the first wiring board includes a first wiring layer provided on the second main surface and extending in the first direction along the second main surface; the first wiring layer electrically connects one end of each of the two spirally wound conductors included in the first coil at a central portion to the first pads via vias; the second coil includes a structure in which two conductors wound in a spiral shape along the third main surface are connected to each other; Isolator.

2. The second wiring board includes a second wiring layer provided on the fourth main surface and extending in the first direction; 2. The isolator according to claim 1, wherein the second wiring layer electrically connects one end of each of the two spirally wound conductors included in the second coil at the center thereof to each of the second pads via vias.

3. 2. The isolator according to claim 1, wherein the first pad of the first wiring board is disposed at a height between the first coil and the second coil.

4. 2. The isolator according to claim 1, wherein a distance from the first main surface of the first insulating layer to the first pad is shorter than a distance from the first main surface of the first insulating layer to the second pad.

5. 2. The isolator according to claim 1, wherein the first main surface of the first insulating layer has a region that does not overlap with the third main surface of the second insulating layer, and the first pad is disposed in the region.

6. a third insulating layer provided between the first coil and the second coil; The isolator of claim 1 , wherein the third insulating layer comprises polyimide.

7. 2. The isolator according to claim 1, wherein the length of the second wiring board in the first direction is shorter than the length of the first wiring board.

8. the first wiring board has a first via provided in the first insulating layer and connecting the first coil and the first wiring layer, and a second via provided in the first insulating layer and connecting the first pad and the first wiring layer, 3. The isolator according to claim 2, wherein the second wiring board has a third via provided in the second insulating layer and connecting between the second coil and the second wiring layer.

9. the first wiring board includes a fourth insulating layer and a fifth insulating layer sandwiching the first coil and the first wiring layer, The isolator according to claim 2 , wherein the second wiring board includes a sixth insulating layer and a seventh insulating layer that sandwich the second coil and the second wiring layer.

10. The isolator according to claim 2 , wherein the first coil, the second coil, the first wiring layer, and the second wiring layer contain copper.

11. 2. The isolator according to claim 1, wherein the thickness of each of the first coil and the second coil is not less than 6 μm and not more than 12 μm.

12. 2. The isolator of claim 1, wherein the first coil and the second coil comprise copper.

13. 2. The isolator according to claim 1, wherein the first wiring board and the second wiring board are flexible printed wiring boards.

14. a first semiconductor chip connected to the first pad of the first wiring board via a first wire; a second semiconductor chip connected to the second pads of the second wiring board via second wires; 10. The isolator of claim 1 further comprising:

15. the first semiconductor chip has a transmitting circuit; the second semiconductor chip has a receiving circuit; the first pad is electrically connected to the transmission circuit; 15. The isolator of claim 14, wherein the second pad is electrically connected to the receiving circuit.

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