JP2005044997A - Electrical circuit unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrical circuit unit which assures easier manufacture of a transformer and mounting on a printed circuit board. <P>SOLUTION: The electrical circuit unit U is formed by mounting a plurality of circuit components on a multilayer printed circuit board 6. In the circuit board 6, conductive layers are respectively formed to the front/rear layers and to an internal layer formed of the adequate number of layers, and the conductive layers are electrically connected adequately through the through-holes 7. A plurality of wiring type conductive patterns W, X, Y, and Z different from a conductive pattern of the conductive layer are formed adequately to the front/rear layers and internal layer of the multilayer printed circuit board 6, and to the overlapped region in the thickness direction of the multilayer printed circuit board 6. Moreover, through-hole is formed to the multilayer printed circuit board 6 at the center area of each wiring type conductive pattern, an intermediate leg of an E type core 101 is inserted into the through hole from the front surface of the multilayer printed circuit board 6, and the I type core 102 is magnetically coupled with the E type core 101 at the rear surface side in order to form a transformer T with the core 10, a primary winding and a secondary winding 51. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electric circuit unit in which a plurality of electronic circuit components such as a transformer are mounted on a multilayer printed board.

  Conventionally, a plurality of electronic circuit components are mounted on a printed wiring board provided with a conductive pattern to constitute an electric circuit unit, for example, an inverter circuit. A transformer is mounted on the printed wiring board together with other electronic circuit components (IC, capacitor, etc.). As shown in FIG. 1, a conventional transformer TR includes a hollow cylindrical bobbin 1 made of synthetic resin or the like and having a hollow portion, and a primary winding and a secondary winding 2 wound around the bobbin 1. , And a core 3 made of a magnetic material such as ferrite inserted into the hollow portion of the bobbin 1.

  However, in the transformer TR as described above, the primary winding and the secondary winding 2 are wound around the bobbin 1, and the lead terminals (not shown) of the primary winding and the secondary winding 2 are respectively connected to the pins 4 Since the work such as winding and soldering is necessary, the manufacturing process of the transformer becomes complicated, and the dimensions of the transformer, especially the height, will be higher than other electronic circuit components. There was a problem that the electric circuit unit would be enlarged.

Therefore, in recent years, a plurality of sheet-like base materials provided with conductive patterns are stacked to form a multilayer substrate, and the conductive patterns of the base materials are electrically connected to each other to form a primary winding and a secondary. A thin transformer is used which is formed by forming a winding and connecting a pair of cores so as to sandwich the multilayer substrate.
Japanese Patent Application Laid-Open No. 6-215962

  However, since the transformer described in the above-mentioned patent document is mounted on a printed wiring board by soldering like other electronic circuit components, it is drawn from the conductive pattern applied to the multilayer board constituting the transformer. Since it is necessary to solder a large number of external connection terminals to the conductive pattern on the printed wiring board, it takes much time to mount the transformer on the printed wiring board.

  The present invention is intended to solve such problems of the prior art, and the object of the present invention is to easily manufacture a transformer and to easily mount the transformer on a multilayer printed board. It is to provide an electric circuit unit that can be used in a simple manner.

  In order to achieve the above object, the present invention provides a multilayer printed board in which a conductive layer is formed on each of inner layers comprising front and back layers and an appropriate number of layers, and the conductive layers are electrically connected through through holes as appropriate. In addition, in the electric circuit unit in which a plurality of circuit components are mounted and electrically connected to any one of the conductive layers, the front and back layers and the inner layer of the multilayer printed board are appropriately formed, and the multilayer printed board Forming a plurality of coiled conductive patterns different from the conductive pattern of the conductive layer in a region overlapping in the thickness direction, and providing a through hole in the multilayer printed circuit board at the center of the coiled conductive pattern. The pair of cores is formed by inserting a pole of one core from a front surface (back surface) of the multilayer printed circuit board and magnetically coupling the other core to the one core on the back surface (front surface) side. Characterized by comprising constituting the transformer and the plurality of windings like conductive pattern.

  The present invention is characterized in that at least one of the pair of cores is formed of an E-type core, and the pole is formed of a middle leg of the E-type core.

  According to the electric circuit unit of the present invention, since the work such as winding the primary winding and the secondary winding around the bobbin is unnecessary, the manufacture of the transformer is very easy, and the core is mounted on the multilayer printed circuit board. Transformers can be manufactured simply by doing so, and there is little variation in manufacturing, and a transformer with stable characteristics can be obtained. Furthermore, the transformer can be easily mounted on the multilayer printed circuit board without performing soldering work, and since the bobbin is not required, the transformer can be thinned. As a result, the electric circuit unit can be made thinner and smaller. realizable.

  Hereinafter, an embodiment of an electric circuit unit according to the present invention will be described with reference to FIGS. 2 is a schematic perspective view showing an electric circuit unit according to the present invention, FIG. 3 is a cross-sectional view taken along line MM ′ in FIG. 2, and FIG. 4 is an exploded perspective view showing a multilayer printed board according to the present invention. 5 is a plan view showing a coiled conductive pattern constituting the transformer according to the present invention, and FIG. 5 (W) is a conductive pattern W formed on the surface layer of the multilayer printed board, and FIGS. 5 (X) and 5 (Y) Are conductive patterns X and Y formed in different inner layers, respectively, and FIG. 5 (Z) is a conductive pattern Z formed in the back layer. FIG. 6 is an exploded perspective view of the transformer T according to the present invention, and FIG. 7 is an explanatory circuit diagram showing an equivalent circuit of the transformer according to the present invention.

  As shown in FIG. 2, an electric circuit unit U includes a transformer T and other electronic circuits on a multilayer printed board 6 in which conductive layers 5 having various conductive patterns are applied to the surface layer, the back layer, and the inner layer, respectively. It is configured by mounting components (not shown).

  First, as shown in FIGS. 3 and 4, the multilayer printed circuit board 6 of the present invention has conductive sheets a and b each having a conductive layer 5 disposed on one side, and a conductive sheet having conductive layers 5 disposed on both sides. It consists of a sheet c and two insulating sheets d and d ′. The multilayer printed circuit board 6 has the conductive sheet a, the insulating sheet d, the conductive sheet c, the insulating sheet d ′, and the conductive sheet b so that the surfaces on which the conductive layers 5 of the conductive sheets a and b are arranged face outward. It is configured by sequentially stacking and forming integrally.

  Circuits necessary for mounting electronic circuit components such as capacitors, resistors, various semiconductor chips, and microcomputers necessary for obtaining an electric circuit unit U having desired functions and performances on the conductive layers 5, 5, and 5. A pattern (conductive pattern) is provided. A part of the conductive layer 5 is shown in FIGS. The conductive layers 5, 5, 5 (conductive pattern) of each layer are electrically connected through through holes as appropriate.

  The present invention forms a transformer coil by forming a conductive pattern different from the conductive pattern of each conductive layer 5 on the multilayer printed board 6 provided with such a conductive pattern.

  That is, according to the present invention, as shown in FIGS. 3 and 5, the winding conductive pattern W is formed on the surface layer of the multilayer printed board 6, the winding conductive patterns X and Y are formed on the inner layer, and the winding is formed on the back layer. A conductive pattern Z is formed (see FIG. 5), and the conductive sheets a, b, and c are electrically insulated from each other by insulating sheets d and d ′. Further, the respective winding-like conductive patterns W, X, Y, and Z are electrically connected as appropriate through the through holes 7, and the primary winding of the transformer T is provided in a region overlapping the thickness direction of the multilayer printed board 6. Lines and secondary windings 51 are formed. That is, each winding-like conductive pattern W, X, Y, Z becomes the primary winding and the secondary winding 51 of the transformer T.

  Further, the sheets a, b, c, d, and d ′ are provided with through holes 8a, 8b, and 8b ′, and the through holes 8a, 8b, and 8b are formed in the multilayer printed circuit board 6 by stacking the sheets. 'Is formed. The through-holes 8a, 8b, 8b ′ are respectively formed in the central portion and both outer sides of the respective winding-like conductive patterns W, X, Y, Z, that is, in the central portion and both outer sides of the primary winding and the secondary winding 51. Provided. Moreover, the primary winding and the secondary winding 51 are comprised in the shape wound around the center through-hole 8a.

  Next, a method for mounting the core 10 of the transformer T on the multilayer printed board 6 will be described with reference to FIGS. The core 10 is made of a magnetic material such as ferrite, and is configured by combining an E-type core 101 and an I-type core 102.

  First, the three poles 9a, 9b, 9b 'of the E-type core 101 are inserted into the through holes 8a, 8b, 8b' from the front surface (or back surface) of the multilayer printed board 6 respectively. At this time, the central pole 9a (hereinafter referred to as the middle leg) of the E-shaped core 101 is inserted into the central through hole 8a. Then, the I-shaped core 102 is joined to the E-shaped core 101 via the plate-shaped resin film 12 on the back surface (or front surface) side of the multilayer printed circuit board 6 to form a Japanese character-shaped core 10, and a closed magnetic circuit is formed. Form. Then, the left and right legs 111 and 111 of the substantially U-shaped metal fitting 11 are inserted into the gaps of the through holes 8b and 8b ′ from the front surface (or the back surface) of the multilayer printed board 6, respectively, and are inserted into the tips of the legs 111 and 111. The E-type core 101 and the I-type core 102 are integrally fixed by locking the provided locking portions 112 and 112 in the vicinity of both ends of the I-type core 102, respectively. At this time, the resin film 12 is inserted between the E-type core 101 and the I-type core 102, whereby the characteristic that the current saturation of the transformer T hardly occurs is obtained. It also serves as an electrical insulation between the core 102 and the conductive layer on the back layer of the multilayer printed circuit board 6. Insulating paper 13 is interposed between the E-type core 101 and the surface layer of the multilayer printed board 6 to electrically insulate the E-type core 101 from the conductive layer 5 on the surface layer of the multilayer printed board 6. . The insulating paper 13 is formed in a plate shape, and is provided with three holes corresponding to the through holes 8a, 8b and 8b '.

  By attaching the core 10 to the multilayer printed circuit board 6 as described above, a transformer in which the primary winding and the secondary winding 51 are wound around the middle leg 9a of the E-type core 101 constituting the core 10 is provided. T is formed. Since the primary winding and the secondary winding 51 are electrically connected to the conductive layer 5, the transformer T is electrically connected to other electronic circuit components via the conductive layer 5. The equivalent circuit of the transformer T is as shown in FIG. 7, and the primary winding is composed of two primary coils P1, P2, and the secondary winding is composed of three secondary coils S1, S2, S3. Is done.

  The above-described embodiment is merely an example of the present invention, and it is obvious that modifications and modifications as appropriate within the spirit of the present invention are included in the claims of the present application. For example, in the present invention, the E-type core and the I-type core are integrally fixed by metal fittings. However, the E-type core and the I-type core may be fixed integrally by winding an insulating tape or the like around the core. .

  Also, by increasing or decreasing the number of inner conductive layers of the multilayer printed circuit board, the number of conductive patterns of each conductive layer, etc. according to the application of the transformer, the number of primary side coils and secondary side coils, It is also possible to arbitrarily change the secondary side voltage or the like. Further, although not shown here, it is also possible to form a winding-like conductive pattern only on the inner layer of the multilayer printed circuit board. In this case, when the core is mounted on the multilayer printed circuit board, the core and the multilayer printed circuit board There is no need to insert insulating paper between the surface layer and the back layer.

  Furthermore, when the length of the middle leg of the E-type core is made shorter than the other two poles, and the E-type core and the I-type core are joined together, You may make it space apart. At this time, the transformer characteristic that current saturation is unlikely to occur similar to the transformer of the above embodiment can be obtained without interposing a resin film on the surfaces where both cores contact each other.

  Further, as shown in FIG. 8, the core 10 includes a cylindrical core 103 composed of a center pole 10a and a cylindrical pole 10b provided so as to surround the center pole 10a, and a rectangular shape facing the cylindrical core 103. Alternatively, a pair of circular plate cores 104 may be used.

Schematic which shows an example of the conventional transformer. The schematic perspective view which shows the electric circuit unit by one Example of this invention. FIG. 3 is a cross-sectional view of an essential part taken along line M-M ′ in FIG. 2. The disassembled perspective view which similarly shows a multilayer printed circuit board. (W) is a plan view showing a conductive pattern W formed on the surface layer of the multilayer printed board, (X) and (Y) are plan views showing conductive patterns X and Y formed on different inner layers, and (Z) is a back layer. The top view which shows the conductive pattern Z formed in. The disassembled perspective view which similarly shows a transformer. The circuit diagram for explanation which shows the equivalent circuit of a transformer similarly. The perspective view which similarly shows other embodiment of a core.

Explanation of symbols

U electric circuit unit T transformer 5 conductive layer 51 primary winding and secondary winding 6 multilayer printed circuit board 7 through hole 8a, 8b, 8b 'through hole 9a middle leg 9b, 9b' pole 10 core 101 E type core 102 I Mold core 10a Center pole 10b Cylindrical pole 103 Cylindrical core 104 Plate core 11 Metal fitting 111 Leg 112 Locking part 12 Resin film 13 Insulating paper W, X, Y, Z Conductive pattern a, b, c Conductive sheet d, d ' Insulation sheet P1, P2 Primary coil S1, S2, S3 Secondary coil

Claims (2)

  Either a plurality of circuit components are mounted on a multilayer printed circuit board in which a conductive layer is formed on each of the front and back layers and an appropriate number of inner layers, and the conductive layers are electrically connected through through holes as appropriate. In the electric circuit unit formed by electrical connection to the conductive layer, the front and back layers and the inner layer of the multilayer printed board are appropriately formed, and the conductive layer is formed in a region overlapping the thickness direction of the multilayer printed board. A plurality of coiled conductive patterns different from the conductive pattern are formed, and a through hole is provided in the multilayer printed circuit board at a central portion of the coiled conductive pattern, and a pole of one core of a pair of cores is formed in the through hole Is inserted from the front surface (back surface) of the multilayer printed circuit board, and the other core is magnetically coupled to the one core on the back surface (front surface) side, and the pair of cores and the plurality of winding conductive patterns Electric circuit unit characterized by comprising constitute a transformer in.   2. The electric circuit unit according to claim 1, wherein at least one of the pair of cores is configured by an E-type core, and the pole is configured by a middle leg of the E-type core.

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