JP2013168553A - Printed coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed coil which can suppress propagation of high frequency noise between a primary winding and a secondary winding.SOLUTION: Shields 4, 5 for spatially shielding between a primary winding 2 and a secondary winding 3 formed in a printed coil 1 are provided. Consequently, parasitic capacitance between the primary winding 2 and the secondary winding 3 can be suppressed, and propagation of high frequency noise between the primary winding 2 and the secondary winding 3 can be suppressed.

Description

  The present invention relates to a printed coil in which concentric spiral primary and secondary windings are formed by a multilayer wiring board formed by stacking printed circuit boards, and the windings are insulated using magnetic coupling.

  Conventionally, a printed coil in which a spiral primary winding and a secondary winding are arranged on a printed board is formed and used as an insulated power converter or an insulated signal transmission device. Such a printed coil can be insulated using the magnetic coupling between the primary winding and the secondary winding.

Japanese Patent Laid-Open No. 04-152609

In this type of printed coil, for example, Patent Document 1 proposes that the upper and lower surfaces of the printed coil are sandwiched by shield surfaces in order to prevent unnecessary leakage electromagnetic fields generated from the coil.
However, in such a configuration, although the leakage electromagnetic field generated from the printed coil can be reduced, the high frequency noise due to voltage fluctuation, for example, is caused by the parasitic capacitance generated between the primary winding and the secondary winding. There is a problem that a device (for example, an IGBT gate drive circuit) connected to the printed coil malfunctions.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a printed coil that can suppress high-frequency noise from propagating between a primary winding and a secondary winding.

  According to the present invention, a shield portion having a planar structure is located between the primary winding and the secondary winding, and the shield portion is fixed at a constant potential. The parasitic capacitance between the windings can be suppressed. Thereby, it can suppress that high frequency noise propagates between a primary winding and a secondary winding. Moreover, since the shield part is formed in a plane structure by laminating spiral through-hole pins formed on the printed circuit board in the lamination direction of the multilayer wiring board, the shield part can be easily formed.

The bottom view of each layer which forms the printed coil in 1st Embodiment of this invention Cross section of printed coil FIG. 1 equivalent view for explaining a method of manufacturing a shield part Electrical diagram Diagram showing how easily high-frequency noise is transmitted The figure which shows the manufacturing method of PALAP Diagram showing change in elastic modulus with temperature FIG. 1 equivalent view showing a second embodiment of the present invention 2 equivalent diagram 4 equivalent figure FIG. 1 equivalent view showing a third embodiment of the present invention 4 equivalent figure FIG. 1 equivalent view showing a fourth embodiment of the present invention FIG. 1 equivalent view showing a fifth embodiment of the present invention 2 equivalent diagram FIG. 1 equivalent view showing a sixth embodiment of the present invention 2 equivalent diagram 4 equivalent figure

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
The present invention utilizes a technique for manufacturing a multilayer wiring board by laminating a plurality of flexible printed circuit boards in which conductor patterns and via holes are formed on a flexible resin film and then hot-pressing them together. . This technique is called PALAP (registered trademark). First, the PALAP will be described in principle with reference to FIGS.

  The flexible printed circuit board used in PALAP is based on a resin film made of a thermoplastic resin, such as a crystal transition type thermoplastic resin. When the specific example of the component of this resin film is shown, for example, polyether ether ketone (PEEK) resin 35-65 mass%, polymer ether imide (PEI) 35-65 mass% are included, and thickness is 25-75 micrometers is preferable. Has been. As shown in FIG. 7, such a crystal transition type thermoplastic resin becomes soft at, for example, around 200 ° C., but becomes hard at lower or higher temperatures (at higher temperatures (about 400 ° C.)). It dissolves) and keeps hard even at around 200 ° C. when the temperature drops from a high temperature.

FIG. 6 shows a method for manufacturing PALAP. As shown to (a), conductor foil (thickness of about 18 micrometers) b which consists of metal foil, such as copper foil and aluminum foil, is affixed on the single side | surface of the resin film a, and this conductor foil b is etched. A conductor pattern c is formed as shown in FIG. After the formation of the conductor pattern c, a protective film d is attached to the surface of the resin film a where the conductor pattern c is not formed.
Thereafter, a laser is irradiated from the protective film d side to form a bottomed via hole e having the bottom surface of the conductor pattern c as shown in (c). The via hole e is formed by adjusting the laser output and the irradiation time so as not to open the conductor pattern c. As a laser used for forming the via hole e, a carbon dioxide laser, an excimer laser, or the like can be considered. In addition, although machining such as drilling may be performed, a laser is preferable for making a fine hole.

When the formation of the via hole e is completed, the conductive paste f is then filled in the via hole e as shown in FIG. The conductive paste f is printed and filled in the via hole e with the conductor pattern c side down by a screen printing apparatus using a metal mask. Then, after printing and filling with the conductive paste f, the protective film d is peeled off as shown in FIG. The flexible printed circuit board g is manufactured as described above.
A plurality of flexible printed circuit boards g manufactured in this way are stacked so that the conductor pattern c is on the bottom. At this time, the uppermost flexible printed circuit board g may be connected to the electronic component or the external wiring and the conductive paste f of the via hole e. However, as shown in FIG. For example, the conductive pattern c may be laminated so that the electronic pattern or the external wiring is connected to the conductive pattern c.

  When the flexible printed circuit board g is laminated, in order to protect the conductor pattern c of the lowermost flexible printed circuit board g, the flexible printed circuit board g is laminated on the cover layer h as the lowermost film. When the uppermost flexible printed circuit board g is laminated so that the conductor pattern c faces upward, the cover layer h is placed on the uppermost flexible printed circuit board g in order to protect the conductive pattern c.

  After laminating a plurality of flexible printed circuit boards g, the flexible printed circuit boards g are pressed at a pressure of 0.1 to 10 MPa at 200 to 350 ° C. by a vacuum press (not shown) (hot press). Since the resin film a of the flexible printed circuit board g undergoes a change in elastic modulus with respect to temperature as shown in FIG. 7, the resin films a are fused to each other by being pressed in a softened state by this hot press. A multilayer wiring board i is completed.

  In this completed form, the conductor patterns c of the plurality of flexible printed circuit boards g are electrically connected to each other through through holes made of the conductive paste f in the via holes e, and electronic components are embedded therein. In this case, the component is also electrically connected to the conductor pattern c directly or through a through hole of the via hole e. The multilayer wiring board i is manufactured as described above. After that, when mounting the electrical / electronic component through the multilayer wiring board i through a reflow furnace, it is heated to about 300 ° C., but at this temperature, the resin film a is not softened and kept in a crystalline state. It is.

FIG. 2 shows a cross section of the printed coil of the present embodiment manufactured using the PALAP technology described above. The printed coil 1 is configured by laminating a plurality of, for example, seven flexible printed boards (hereinafter referred to as first to seventh layers) 1a to 1g. In FIG. 2, illustration of the conductor pattern and the cover layer constituting each of the layers 1a to 1g is omitted.
FIG. 1 is a bottom view of each of the layers 1a to 1g, where (a) is the first and second layers 1a and 1b, (b) is the third layer 1c, (c) is the fourth to sixth layers 1d to 1f, (d ) Is a bottom view of the seventh layer 1g.
In the third layer 1c, a primary winding 2 and a secondary winding 3 are formed by a conductor pattern. That is, the primary winding 2 and the secondary winding 3 are formed in a three-turn rectangular spiral shape by the conductor pattern of the third layer 1 c that is the middle of the printed coil 1. The primary winding 2 and the secondary winding 3 are wound concentrically (with the center being the same), and the respective windings are alternately positioned outward from the center.

  On the other hand, between the primary winding 2 and the secondary winding 3, there are formed three-turn rectangular spiral shield portions 4, 5 concentric with the windings 2, 3. The shield part 4 is formed so that the primary winding 2 is located outside and the secondary winding 3 is located inside, and the shield part 5 is the secondary winding 3 located outside and the primary winding 2 located inside. It is formed to do. The shield parts 4 and 5 are constituted by through-hole pins penetrating from the first layer 1a to the sixth layer 1f. That is, the shield portions 4 and 5 are formed by connecting individual through-hole pins formed in the first to sixth layers 1a to 1f continuously in the stacking direction. Thereby, the shield parts 4 and 5 have a surface structure orthogonal to the surface directions of the primary winding 2 and the secondary winding 3.

FIG. 3 is a view corresponding to FIG. 1 for explaining a method of manufacturing the shield portions 4 and 5. The circles shown in FIG. 3 schematically show via holes 6a formed by laser irradiation, and the long holes 6 for filling the conductive paste by forming the via holes continuously in a rectangular spiral shape. Forming. As described in the PARAP manufacturing method, the long hole 6 forms a bottomed groove portion whose bottom surface is a conductor pattern, so that the conductive paste filled in the long hole 6 does not fall. Moreover, since the both side parts isolate | separated by the long hole 6 at the spiral form are connected by the conductor pattern, the intensity | strength of the layer in which the long hole 6 was formed does not fall extremely.
As a result of the configuration as described above, shield portions 4 and 5 having a surface structure that spatially shields the primary winding 2 and the secondary winding 3 are interposed.

Through holes 2a and 3a are formed in the third to seventh layers 1c to 1g. The through holes 2a and 3a are configured by connecting through hole pins penetrating the third to seventh layers 1c to 1g, respectively. The through holes 2a and 3a located in the seventh layer 1g are connected to terminals 2b and 3b formed at the end of the seventh layer 1g.
The primary winding 2 reaches the third layer 1c from the terminal 2b provided on the seventh layer 1g via the through hole 2a, and turns three times to reach the terminal 2c provided on the third layer 1c. Is a line. The secondary winding 3 is a winding that reaches the third layer 1c from the terminal 3b provided in the seventh layer 1g via the through-hole 3a, and makes three turns to reach the terminal 3c.
The shield parts 4 and 5 are provided with terminals 4a and 5a at the end of the third layer 1c.
1 and 2, only the printed coil 1 is shown, but the printed coil 1 is actually formed in a predetermined area of the multilayer wiring board, and the terminals 2b, 3b, 2c, 3c, 4a, 5a are It is connected to an electronic circuit formed on the multilayer wiring board or an electronic circuit mounted on another printed circuit board.

FIG. 4 is an electric circuit diagram showing an application example of the IGBT using the printed coil 1 composed of the primary winding 2 and the secondary winding 3 to the gate drive circuit of the IGBT. The primary winding 2 is driven by a drive circuit 7. The drive circuit 7 is connected to a power source 8 and a reference potential GND 9 on the input side, and further connected to a signal input IN 10. The output side of the drive circuit 7 is connected to the terminal 2b of the primary winding 2, and the GND 9 is connected to the terminal 2c.
The input side of the drive circuit 11 for the IGBT gate is connected to the terminal 3b of the secondary winding 3, and the power supply 12 and the reference potential 13 on the output side are connected to the drive circuit 11. A terminal 3 c of the secondary winding 3 is connected to the reference potential 13. The output side of the drive circuit 11 is connected to the gate terminal of the IGBT 14, and the reference potential 13 is connected to the emitter terminal of the IGBT 14.

The terminals 4a and 5a of the shield portions 4 and 5 are connected to the reference potential GND9 on the input side and fixed to GND. With this configuration, high-frequency noise due to voltage fluctuation, for example, transmitted through the printed coil 1 via the parasitic capacitance between the primary winding 2 and the secondary winding 3 can be shielded by the shield portions 4 and 5. it can. Therefore, since the high frequency noise flows through the shield portions 4 and 5, the high frequency noise propagating to the secondary winding 3 can be reduced.
In FIG. 4, the shield portion 5 is illustrated at a position away from between the primary winding 2 and the secondary winding 3, but this is to express the difference in the positional relationship between the shield portions 4 and 5. is there. That is, the shield part 4 has the primary winding 2 on the outside and the secondary winding 3 on the inside, whereas the shield part 5 has the secondary winding 3 on the outside and the primary winding on the inside. This is because the line 2 is located, and the shield part 5 is located between the primary winding 2 and the secondary winding 3 similarly to the shield part 4. Such an expression method is the same in the following embodiments.

  FIG. 5 shows a result of comparing the ease of transmission of high-frequency noise due to voltage fluctuations with and without the shield portions 4 and 5. It can be seen that high frequency noise is easily transmitted when the shield portions 4 and 5 are not provided (b), whereas high frequency noise is difficult to be transmitted when the shield portions 4 and 5 are provided (a).

  When the thickness of one layer is 75 um, the thickness of the shield portions 4 and 5 penetrating the six layers 1a to 1f is 450 um, and the primary winding 2 and the secondary winding 3 are formed of the shield portions 4 and 5. Located at the center of thickness. The diameter of the through-hole forming the shield parts 4 and 5 is 100 um in diameter, the primary winding 2 and the secondary winding 3 are set to a width of 150 um, and the distance between the center of the winding part and the center of the shield part is set to 400 um. Yes. This is because the primary winding 2 and the secondary winding 3 are positioned substantially at the center of the thickness of the shield portions 4 and 5, and the shield portion 4 is more than the distance between each of the windings 2 and 3 and the shield portions 4 and 5. , 5 has a thickness dimension, the shielding effect is particularly high. Therefore, in this embodiment, the dimensions of the respective parts are set so as to have such a relationship.

According to such an embodiment, the following effects can be produced.
Since the shield portions 4 and 5 that shield between the primary winding 2 and the secondary winding 3 are provided, the parasitic capacitance between the primary winding 2 and the secondary winding 3 can be suppressed, and the printed coil 1 Propagation of high frequency noise can be suppressed.
Since the shield portions 4 and 5 are formed by electrically connecting the through-hole pins formed in the respective layers 1a to 1f when the printed coil 1 is manufactured by PALAP, the shield portions 4 and 5 are easily formed. can do.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 8 to 10. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In the following embodiments, the same parts as those of the previously described embodiments are denoted by the same reference numerals, and the description thereof is omitted. The second embodiment is characterized in that the primary winding 2 and the secondary winding 3 are surrounded by shield portions 4 and 5.
8A is a bottom view of the second layer 1b, FIG. 8B is a third layer 1c, FIG. 8C is a fourth layer 1d, and FIG. 8D is a bottom view of the seventh layer 1g.
The second and fourth layers 1b and 1d are respectively formed with a shield surface 21 by a conductor pattern, and the third and fourth layers 1c and 1d are formed with shield portions 4 and 5 (see FIG. 9). Since the shield parts 4 and 5 formed in the third and fourth layers 1c and 1d are electrically connected to the two shield surfaces 21, the primary winding 2 and the secondary winding 3 are shield parts 4 and 5, respectively. It will be surrounded by. In this case, since the shield portions 4 and 5 are electrically connected by the shield surface 21, they can be regarded as an integrated object electrically.

Here, the shield surface 21 is formed in a rectangular frame shape corresponding to the formation region of the primary winding 2 and the secondary winding 3, and is divided by a slit 22 so as not to form a closed loop. This is because an eddy current flowing in a closed loop shape on the shield surface 21 is blocked by a high-frequency magnetic field generated when a high-frequency signal flows through the primary winding 2. On the other hand, portions of the shield portions 4 and 5 corresponding to the slits 22 of the shield surface 21 are divided by the slits 23. This is to prevent the eddy current generated on the shield surface 21 from flowing through the shield portions 4 and 5.
In the case of the above configuration, since the shield portions 4 and 5 are electrically integrated by the shield surface 21, the electric circuit diagram can be expressed as shown in FIG.

According to such an embodiment, the primary winding 2 and the secondary winding 3 are spatially surrounded by the shield portions 4, 5, and therefore, between the primary winding 2 and the secondary winding 3. Parasitic capacitance can be effectively suppressed.
Since the layer occupied by the printed coil 1 can be limited to the two layers 1c and 1d, the printed coil 1 can be miniaturized and a layer not used as the printed coil 1 can be used for other purposes. be able to.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. The third embodiment is characterized in that the inductance of the shield parts 4 and 5 is reduced.
As shown in FIG. 11, the shield portions 4 and 5 are divided by a slit 31. Of the divided shield parts 4 and 5, the end part of the spiral center side is connected to the terminals 9 through the through holes 4b and 5b formed in the seventh layer 1g to the terminals 9c and 5c. It is fixed (see FIG. 12).
According to such an embodiment, since the inductance of the shield parts 4 and 5 can be reduced by shortening the total length of the shield parts 4 and 5, the high-frequency transmission characteristic of the printed coil 1 is improved, and further, the high frequency This signal can also be transmitted.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is characterized in that the slits 31 that divide the shield portions 4 and 5 described in the third embodiment are not arranged linearly between the primary winding 2 and the secondary winding 3. Have
In the third embodiment, the slits 31 that divide the shield portions 4 and 5 are linearly arranged between the primary winding 2 and the secondary winding 3, and the primary winding 2 is interposed via the slit 31. And a part of the secondary winding 3 are electrically coupled. On the other hand, in this embodiment, as shown in FIG. 13, the slit 31 is formed so as to be shifted in the direction along the primary winding 2 and the secondary winding 3. It is configured not to line up linearly between the next windings 3.
According to such an embodiment, since the slits 31 of the shield portions 4 and 5 are not linearly arranged between the primary winding 2 and the secondary winding 3, the primary winding 2 and the secondary winding Part of the winding 3 is not electrically coupled via the slit 31, and the parasitic capacitance between the primary winding 2 and the secondary winding 3 can be further reduced.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIGS. The fifth embodiment is characterized in that the primary winding 2 and the secondary winding 3 are arranged in different layers.
FIG. 14A is a bottom view of the first layer 1a, and FIGS. 14B to 12G are bottom views of the second to seventh layers 1b to 1g. Shield portions 4 and 5 are formed on the third to sixth layers 1c to 1f (see FIG. 15), and the second, fourth and sixth layers 1b, 1d and 1f are each provided with a rectangular frame-shaped shield surface 21 by a conductor pattern. Is formed. This shield surface 21 is divided by a slit 22.
On the other hand, a primary winding 2 is formed on the third layer 1c and is connected to a terminal 2b provided on the first layer 1a via a through hole 2a formed on the first to third layers 1a to 1c. Has been. A secondary winding 3 is formed on the fifth layer 1e, and is connected to a terminal 3b provided on the seventh layer 1g via a through hole 3a formed on the fifth to seventh layers 1e to 1g. Yes.
As shown in FIG. 15, the primary winding 2 and the secondary winding 3 are arranged so as to be in a positional relationship overlapping in the stacking direction, and the windings 2 and 3 are respectively separated by shield portions 4 and 5. Surrounded.
According to such an embodiment, since the primary winding 2 and the secondary winding 3 are arranged in different layers, the winding density of the windings 2 and 3 can be increased.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIGS. The sixth embodiment is characterized in that the primary winding 2 and the secondary winding 3 are each surrounded by a spiral shield portion.
As shown in FIG. 16, the shield portions 4 formed on the third and fourth layers 1 c and 1 d are formed on both sides of the primary winding 2 and sandwich the primary winding 2. The shield portions 5 formed on the fifth and sixth layers 1e and 1f (see FIG. 17) are formed on both sides of the secondary winding 3 and sandwich the secondary winding 3 therebetween.
On the second, fourth, and sixth layers 1b, 1d, and 1f, spiral shield surfaces 41 are formed along the primary winding 2 and the secondary winding 3, and are electrically connected to the shield portions 4 and 5. doing.
As shown in FIG. 17, the primary winding 2 and the secondary winding 3 positioned so as to overlap with each other in the stacking direction are surrounded in a spiral shape by shield portions 4 and 5 that spatially surround them.
An electric circuit diagram showing the above configuration can be expressed as shown in FIG.
According to such an embodiment, since the shield surface 41 is spiral and does not form a closed loop and eddy current does not flow, there is no need to divide the shield portions 4 and 5 by slits, and the primary winding. The parasitic capacitance between the secondary winding 3 and the secondary winding 3 can be effectively suppressed.

(Other embodiments)
The present invention is not limited to the above embodiment, and can be modified or expanded as follows.
The primary winding 2 and the secondary winding 3 are not limited to a rectangular frame-like spiral shape, and may be formed in a spiral shape such as an annular shape, an elliptical shape, or a polygonal shape.
The layers constituting the printed coil 1 are not limited to seven layers.
The terminals 4a and 5a of the shield portions 4 and 5 are not limited to being connected to the input-side reference potential GND9, both terminals are connected to the power supply 8, and both terminals are connected to the power supply 12. Both terminals can be connected to the reference potential 13 on the output side, or the terminals 4a and 5a can be connected to different terminals (for example, the power supply 8 and the power supply 12). That is, as long as the shield portions 4 and 5 can be fixed at a constant potential, the potential is not limited.
A plurality of slits 22 and 31 of the second to fourth embodiments may be provided. In this case, since both sides of the slit can be connected by the slits 22 and 31, the strength of the single layer can be increased.
The present invention may be applied to an insulated power converter.

  In the drawings, 1 is a printed coil, 2 is a primary winding, 3 is a secondary winding, and 4 and 5 are shield portions.

Claims (7)

Concentric spiral primary winding (2) and secondary winding (3) are formed by a predetermined conductive pattern of a multilayer wiring board formed by laminating a plurality of printed circuit boards having a conductive pattern, and these windings In the printed coil (1) which insulates between using magnetic coupling,
A shield portion (4, 5) for shielding between the primary winding and the secondary winding;
The shield part is configured in a plane structure by laminating through-hole pins formed on the printed circuit board along the primary and secondary windings and also in the laminating direction of the multilayer wiring board and has a constant potential. A printed coil characterized by being fixed to the wire. A shield pattern (21, 41) formed by a conductor pattern located in the stacking direction of the primary winding and the secondary winding and electrically connected to the shield portion,
The printed coil according to claim 1, wherein the primary winding and the secondary winding are spatially surrounded by the shield portion. The shield surface has a surface shape so as to cover the entire primary winding and secondary winding, and a slit (22) so as not to form a closed loop with a vortex center of the primary winding and secondary winding. Divided by
The printed coil according to claim 2, wherein the shield part is divided by a slit (23) at a portion facing the slit.   The printed coil according to claim 2, wherein the shield surface is formed in a spiral shape along the primary winding and the secondary winding.   The printed coil according to claim 2, wherein the shield part has an intermediate portion divided by a slit.   The printed coil according to claim 5, wherein the slit is provided so as not to be linearly arranged between the primary winding and the secondary winding. The primary winding and the secondary winding are provided at substantially the center in the thickness direction of the shield part,
7. The print according to claim 1, wherein a dimension in a thickness direction of the shield part is not less than a distance dimension between the primary winding and the secondary winding and the shield part. coil.

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