JPH0234810Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a module in which an electronic circuit including a plurality of coils is provided on a magnetic substrate. A surface-mountable electronic circuit module having a structure in which a protrusion is formed, a plurality of coils are wound around the protrusion on one side, and external connection electrodes are formed on the protrusion on the other side. It is something.

The present invention relates to a module suitable for, but not limited to, cases where an electronic circuit including a coil is integrated as a single functional component, such as a DC-DC converter, and is incorporated into other electronic equipment as it is. It is something.

[Conventional technology]

Electronic circuit modules are already publicly available in which a plate-shaped magnetic material made of ferrite or the like is used as a circuit board, and a coil is attached to a part of the board by utilizing its magnetic properties. Various proposals have been made regarding the formation structure of winding elements such as transformers and inductors, and one of the most representative ones is the
This is a technology disclosed in Publication No. 45985.

The technology disclosed herein uses a magnetic substrate in which three or more sets of cut grooves are formed so as to face each other from both long sides of a rectangular magnetic plate toward the center, and a circuit pattern is formed on the surface. A coil is formed by winding a wire around a cut groove. Each coil is then connected to the circuit pattern so that the magnetic fields generated from them are in opposite directions. Various circuit components are mounted on the magnetic substrate, and a plurality of lead pins for external connection are attached to the ends.

[Problem that the invention attempts to solve]

However, in an electronic circuit module having such a structure, one coil is formed across a pair of opposing cut grooves, and the substrate serves as the core of the wire rod, making the coil forming process quite troublesome. In order to avoid magnetic interference, at most every other groove can be used as a winding core. Furthermore, since windings are also applied to the middle part of the board, not only does the area for mounting circuit components become smaller, but it also creates major restrictions on circuit pattern design.As a result, there are many When mounting components, the magnetic substrate itself becomes large and has a complicated shape, which causes the disadvantage that it is easily damaged.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, make it possible to form a plurality of winding elements extremely easily, reduce the coupling between them, and place each winding element on the edge of a substrate in a small size. Since it can be formed in a single area, there is a high degree of freedom in circuit pattern design, and the mounting area for components can be expanded, making it possible to further reduce the size of the circuit. An object of the present invention is to provide an electronic circuit module including a coil.

[Means for solving problems]

The present invention, which can achieve the above objectives, has made significant improvements in the shape of the magnetic substrate, the direction in which the coil is attached, the shape of the protrusion that serves as the coil core, and the structure of the external connection part. . That is, the magnetic board has a substantially rectangular main body portion with a plurality of first and second protrusions connected to each other on two opposing sides, and the first protrusions are recessed from the board mounting surface. The electronic circuit module has a structure in which a plurality of coils are wound around the first protrusion, and external connection electrodes are formed on the board mounting surface of the second protrusion.

Here, as the magnetic substrate, for example, a sintered ferrite plate is suitable. The step recessed from the board mounting surface of the first protrusion is made by adjusting the wire diameter and winding state of the coil wire so that it does not protrude beyond the board mounting surface when the coil is mounted across one or more protrusions. Selected with consideration. As the coil, a self-fusion type coil wire material formed and fused into an air-core coil shape is used.

Circuit patterns such as conductive patterns or resistive films provided on the surface of the magnetic substrate, external connection electrodes, etc. can be easily formed using well-known printing wiring technology for hybrid ICs and the like. Since it is difficult to form through holes in the case of a ferrite substrate, the end surface of the magnetic substrate can be used to connect the circuit pattern on the component mounting surface and the external connection electrode on the substrate mounting surface. Of course, this can also be done by covering the second protrusion with a metal cap or the like. Circuit components include chip capacitors, chip resistors, chip transistors,
An IC or the like is used, and small diodes or the like can also be directly connected by soldering.

[Effect]

The magnetic substrate functions not only as a substrate for electronic circuits but also as a magnetic core for multiple coils. When a plurality of coils are arranged in parallel along one side of the magnetic substrate, the magnetic fluxes that try to combine between the coils are canceled out, leakage magnetic flux is reduced, and saturation of the core is prevented. In the present invention, since the coil is wound in the longitudinal direction of the substrate, the winding mechanically strengthens the substrate. Furthermore, since the coil is formed along one side of the magnetic substrate, most of the area of the substrate is left open for mounting circuit patterns and components, allowing for high-density integration and requiring a small substrate area.

The circuit module according to the present invention is surface-mounted on a printed wiring board or the like in a leadless structure using external connection electrodes formed on the board mounting surface side.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on the drawings. FIG. 1 is an exploded perspective view showing one embodiment of the electronic circuit module according to the present invention, and FIG. 2 is an explanatory view showing the state when it is mounted on a printed wiring board.

The magnetic substrate 10 is made of sintered ferrite, and has six first protrusions 14 extending outward on one long side of a substantially rectangular main body portion 12, and the opposite long side. Six second protrusions 16 facing outward are also arranged in series on the side, and the first protrusions 14 are connected to the board mounting surface A (the surface facing the printed wiring board, that is, the surface that is not visible in FIG. 1). It has a stepped structure that is slightly concave compared to the surface of the wall. Here, the first and second protrusions 14, 16 are designed to have the same width.

A desired circuit pattern is formed on the front and back surfaces of such a magnetic circuit board 10. This circuit pattern is a conductive pattern, a resistive film, etc., and is a hybrid
Like ICs, it is formed by screen printing and then baking. The second protrusion 16 on the substrate mounting surface A side of the magnetic substrate 10 includes:
External connection electrodes 18 are formed respectively. In addition, external connection electrodes 20 are appropriately formed at the ends of the magnetic substrate 10. These electrodes 18,2
0 can be formed in the same manner as the circuit pattern by the screen printing method as described above, and
It is also possible to use the side end surfaces of the magnetic substrate 10 to establish electrical conduction with the component mounting surface B side. Using the circuit pattern, various circuit components 22 such as chip capacitors, chip transistors, ICs, diodes, etc. are mounted on the component mounting surface B side as shown in FIG.

A coil 24 is attached to the first protrusion 14 of the magnetic substrate 10 . These coils 24 may be wound around each protrusion 14, or may be wound so as to span a plurality of protrusions. In other words, by selecting the number of protrusions included in each coil, it is possible to adjust the inductance of that coil. These coils 24 are formed into an air-core coil shape using, for example, a self-fusing wire material called cement wire, and are inserted into the protrusion to form a connection pattern in which the terminal is provided in the shape of a magnetic substrate. Can be installed by soldering.

The assembled electronic circuit module is inserted into a case so that the board mounting surface A is exposed, or is molded or coated with resin.
The magnetic substrate and internal circuitry will be protected.

The electronic circuit module configured in this way is
As shown in FIG. 2, the board mounting surface A is placed so as to be in contact with the printed wiring board 26, and surface mounting is performed by soldering or the like using the external connection electrodes 18, 20. Since the external connection electrode 18 is formed on a protruding portion, the heating portion is localized and soldering can be easily performed. The other external connection electrode 20 may not be provided, but if the magnetic substrate 10 becomes large and the connection strength is insufficient with only the electrode 18 provided on one side, it is preferable to provide it. During surface mounting, as described above, the first protrusion 14 around which each coil 24 is wound has a stepped structure that is recessed from the board mounting surface A. It doesn't get in the way at all. In this way, an electronic circuit module with functions such as a DC-DC converter and a noise filter can be incorporated into a printed wiring board as a single functional component in the same way as ordinary chip components such as resistors and capacitors.

In the present invention, the magnetic substrate 10 functions not only as a normal circuit board but also as a magnetic core of each coil. Since each coil is arranged along one side of the magnetic substrate 10, magnetic fluxes caused by magnetic interference from each other are canceled out, leakage magnetic flux is reduced, and saturation of the core can be prevented. This is the third
To explain with a diagram, the magnetic fluxes φ ₁ and φ ₂ , φ ₂ and φ ₃ , and φ ₃ and φ ₄ that span between the protrusions cancel each other out,
Single magnetic flux Ф ₁ , Ф ₂ , Ф that does not span between the protrusions
This is because only ₃ and _Ф4 remain.

Although not shown in FIG. 1, it is desirable to chamfer the first protrusion 14 on the side to which the coil is attached. This is because the coil 24 can be easily inserted without damaging it.

The shape of the protrusion formed on the magnetic substrate (the width is the protrusion length) is arbitrary. For example, by changing the length of the protrusion and shifting the coil winding position, magnetic interference between adjacent coils can be further reduced. Furthermore, between the tip of the first protrusion and the substrate main portion, or the first
A closed magnetic circuit structure can be created by attaching another magnetic member between the tips of the protrusions.

It is also possible to configure a desired electronic circuit, such as a converter circuit, with the two modules by configuring only the coil as the main component and related parts using this module, and configuring other active components using other monolithic or hybrid ICs. It is possible.

As the substrate material, not only ferrite but also metal magnetic materials and the like can be used. In that case, unlike ferrite, the surface electrical resistance is low, so it goes without saying that the circuit pattern is formed after coating with an electrically insulating resin. Of course, even in the case of a substrate using ferrite, if the surface resistance is too low, it may be coated with resin.

[Effect of idea]

Since the present invention is a surface-mounted circuit module that includes a coil configured as described above, if an air-core coil is prepared in advance, the winding element can be installed extremely easily by simply fitting it into the protrusion of the magnetic board. can be formed,
Moreover, since each coil is arranged along one side of the magnetic board, the coupling between the coils is small, and most of the area can be used for mounting circuit patterns and circuit components, making it possible to downsize the magnetic board. It is extremely effective in that an electronic circuit including a coil can be incorporated into a single package to form a functional component.

Further, according to the present invention, the first
The same magnetic substrate can be used to form coils with different inductances depending on the coil shape and the winding position. This has the advantage that the magnetic substrate can be used for various purposes.

In addition, since a large number of protrusions are formed on both sides of the magnetic substrate, the heat dissipation effect is good, and the second
The external connection electrodes formed on the protruding parts of the electronic circuit module allow direct soldering to printed wiring boards, etc. without lead pins, making it possible to make devices smaller and thinner by using this electronic circuit module. There are also advantages.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing one embodiment of an electronic circuit module according to the present invention, FIG. 2 is an explanatory view showing the state when it is mounted, and FIG. 3 is an explanatory view of a magnetic path in a magnetic substrate. 10...Magnetic substrate, 14...First protrusion, 1
6... Second protrusion, 18, 20... External connection electrode, 22... Circuit component, 24... Coil.

Claims (1)

[Scope of utility model registration request] In an electronic circuit module comprising a magnetic substrate, a plurality of coils wound around the magnetic substrate, a circuit pattern formed on the magnetic substrate, and a plurality of external connection parts provided on the magnetic substrate, the magnetic substrate has a substantially square shape. A plurality of first and second protrusions are arranged in series on two opposite sides of the shaped main body portion, the first protrusions have a stepped structure recessed from the board mounting surface, and a plurality of coils are connected to the 1st
1. A surface-mounted circuit module including a coil that is wound around a protrusion of the second protrusion, and has an external connection electrode formed on a substrate mounting surface of the second protrusion.