JPH079587Y2 - DC-DC converter - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is a unitized DC used as a power source for small electric devices such as small video movies and portable personal computers.
-It relates to the structure of the DC converter.

[Conventional technology and its problems]

2. Description of the Related Art In recent years, with the miniaturization of electric equipment, circuit devices around a power supply have been desired to be even thinner and more lightweight.

Conventional DC-DC converters include those having circuit elements mounted on the upper and lower surfaces of a double-sided printed circuit board and those having circuit elements mounted on a single-sided printed circuit board. Since a large current flows through the power circuit, a large amount of heat is generated in the operating DC-DC converter. However, in a converter circuit that incorporates a transformer and uses a lot of choke coils and capacitors, the surface of the printed circuit board is covered with a large number of circuit elements and circuit patterns, so it is difficult to effectively dissipate the heat. It was

Further, in such a DC-DC converter, the most problematic factor in thinning is a transformer mounted on the surface of a printed circuit board. It was structurally difficult to reduce the height of the transformer having the EE core or the EI core for the closed magnetic circuit structure.

[Purpose of device]

The present invention has been made to solve the above problems, and is a DC-type that has excellent heat dissipation and can be thinned.
It is intended to provide a DC converter.

[Means for Solving the Problems]

In the present invention, two magnetic substrates are laminated with a print coil sandwiched between them, a circuit pattern for mounting circuit elements is formed on the upper surface thereof, and an E-shaped core of a transformer is formed on the magnetic substrate so as to form a closed magnetic circuit. The bottom surface of the magnetic substrate with nothing attached to it is fixed to a part of the metal plate for heat dissipation or the metal case for shielding, or without being adhered to the metal plate in advance. It is characterized in that the lower surface of the magnetic substrate is flat so that it can be adhered to the housing of the device.

〔Example〕

1 and 2 show an embodiment of the present invention.

In these figures, 10 and 20 are magnetic substrates made of nickel zinc ferrite or the like. As shown in an enlarged view in FIG. 3, an insulating layer 21 such as a glass film is provided on the upper surface of one magnetic substrate 10, and a circuit pattern 22 made of copper or the like is printed and printed on the insulating layer 21. It is formed by the means. Another circuit pattern 24 is formed on the circuit pattern 22 via an insulating layer 23. These two layers of circuit patterns 22 and 24 are electrically connected through through holes 25. A plurality of printed coils 30 as shown in FIG. 4 connected to the circuit pattern 22 through the through holes 15 are formed on the lower surface of the magnetic substrate 10. Another magnetic substrate 20 is bonded and fixed to the lower surface of the magnetic substrate 10 so as to cover the print coil 30. Reference numeral 22 is a concave portion of the magnetic substrate 20 provided at a position facing the printed coil 30. By thus sandwiching the print coil 30 between the two magnetic substrates 10 and 20, it is possible to obtain a sufficiently large inductance as a choke coil for a power supply circuit, despite the thinness.

On the circuit pattern 24, electrodes 52 and 53 are embedded inside a dielectric plate 51 formed by stacking as shown in FIG. 5 together with a surface-mounted circuit element 40 such as a transistor and a diode. Circuit board pattern 24
It has an electrical connection with. In this embodiment, two such capacitors 50 are provided. Two layers of circuit patterns 62, 64 are formed on the upper surface of the dielectric plate 51 of the capacitor 50 with an insulating layer 63 interposed therebetween, and the surface-mounted circuit element 40 is also mounted on the circuit pattern 64. . A part of the circuit pattern 62 extends to the side surface of the dielectric plate 51, and this part is connected to the circuit pattern 24 by soldering.

As shown in FIG. 6, a through hole 12 is provided in a part of the magnetic substrate 10, and a transformer 70 is attached so that a part is inserted into the hole 12. The transformer 70 has a core 72 having an E-shaped cross section and the magnetic substrate 20 so as to form a closed magnetic circuit.
The ends of 72 are attached to the upper surface of the magnetic substrate 20 so as to abut against each other. Although illustration is omitted, it is preferable to interpose an insulating layer between the core 72 and the magnetic substrate 20 in order to avoid magnetic saturation. A frame 76 made of a synthetic resin in which leads 74 are planted on the side surface is fitted into the core 72. The lead 74 is soldered to the wiring pattern 23 as shown in FIG.

Magnetic substrates 10, 20 and capacitors laminated in this way
50, transformer 70 and other circuit elements incorporated therein
40 is housed in a shield metal case 80 including a bottom plate 81 and a lid 82. The lower surface of the magnetic substrate 20 is adhered and fixed to the bottom plate 81 of the case 80. Reference numeral 90 in FIG. 2 denotes a terminal plate in which terminals 91 for external connection are implanted.

FIG. 8 shows an example in which the transformer 70 is mounted on the magnetic substrate 10. The lower end of the core 72 is butted against the magnetic substrate 10, and a closed magnetic circuit is formed as in the example of FIG. In this case, the height dimension is increased by the thickness of the magnetic substrate 10 compared to the above-mentioned configuration, but the total height is higher than that when a normal transformer is used because the yoke of the transformer 70 also serves as the magnetic substrate 10. Can be reduced.

The capacitor 50 does not necessarily have to be flat. Since the circuit patterns 62 and 64 on the upper surface of the capacitor 50 are eliminated, a slightly larger magnetic substrate 10 is required, but a surface-mounted capacitor may be mounted on the circuit pattern 24. The print coil formed on the lower surface of the magnetic substrate 10 may be provided on the upper surface side of the other magnetic substrate 20.

Further, the magnetic substrate 10 and the circuit pattern on the dielectric plate 51, and the printed coil 30 are not limited to the embodiments, but may be formed in multiple layers with an insulating layer interposed. The lower surface of the magnetic substrate 20 may be adhered only to a single metal plate such as the bottom plate 81, or may be left flat without adhering to the metal plate and its housing when assembled in an electric device. It may be possible to fix it by closely adhering to it.

[Advantages of the Invention] According to the present invention, a large amount of heat is generated because a magnetic substrate with good thermal conductivity is used and the lower surface is fixed to a metal plate or can be closely fixed to the case of electric equipment. It is possible to obtain a DC-DC converter with an extremely high heat dissipation effect even if a built-in transformer is incorporated.

In addition, the coil is built in the thin laminated printed circuit boards, and the transformer, which is a component with a large height, doubles as the magnetic substrate for the yoke to form the closed magnetic circuit structure. It has the effect of significantly reducing the thickness of the DC-DC converter, for example, by reducing the thickness to 6 mm or less.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectional front view showing an embodiment of a DC-DC converter of the present invention, FIG. 2 is a plan view with a part of its case cut away, and FIG. FIG. 4 is an enlarged front sectional view of a part of a magnetic substrate, FIG. 5 is an enlarged front sectional view of a capacitor, FIG. 6 is an enlarged front sectional view of a transformer portion, and FIG. FIG. 8 is an enlarged side sectional view of the transformer portion, and FIG. 8 is an enlarged front sectional view showing another example of mounting the transformer. 10 ・ 20 …… Magnetic substrate, 70 …… Transformer 22 ・ 24 …… Circuit pattern, 72 …… Core 30 …… Print coil, 80 …… Metal case 40 …… Circuit element

Claims (3)

[Scope of utility model registration request] 1. A laminated first and second magnetic material substrate, a printed coil formed on either one of the facing surfaces of both magnetic material substrates, and a through provided on the upper surface of the first magnetic material substrate. A first magnetic substrate provided with a circuit pattern electrically connected to the printed coil through a hole, a circuit element mounted on the circuit pattern, and a transformer having a magnetic core having an E-shaped cross section. The DC is characterized in that a part of the transformer is inserted into the through hole provided in the core, the end of the core is abutted against the second magnetic substrate, and the lower surface of the second magnetic substrate is made flat. -DC converter. 2. A laminated first and second magnetic material substrate, a printed coil formed on one of the opposing surfaces of both magnetic material substrates, and a through provided on the upper surface of the first magnetic material substrate. A circuit pattern electrically connected to the printed coil through a hole, a circuit element mounted on the circuit pattern, and a transformer having a magnetic core having an E-shaped cross section are provided, and an end portion of the core is provided. A DC-DC converter characterized in that the lower surface of the second magnetic material substrate is made flat while being fixed by being abutted against the first magnetic material substrate. 3. The DC-DC converter according to claim 1, wherein a metal plate is fixed to the lower surface of the second magnetic substrate.