JPH11299225A - Dc-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a radiation noise by mounting a reactor winding, terminal, and an electric part inside of a ferrite case serving as the ferrite core of a reactor, and forming a circuit with conductor wiring. SOLUTION: After an electric part 5 is soldered to a printed board 4, an end part of a reactor winding 3 is soldered to a terminal 7 where a bobbin 2 is press-fitted, the terminal 7 and conductor wiring on the printed board 4 are soldered by mounting this reactor in the printing board 4. Next, a bonding agent is applied to an upper surface of the bobbin 2, it is inserted into a ferrite case 1 and bonded. A bonding agent is applied to a ferrite plate 6 having a hole for the terminal 7, the ferrite plate 6 is inserted in the ferrite case 1 so as to insert the terminal 7 to the hole for the terminal, and is bonded and fixed with the printed board 4, electric part 5, ferrite case 1, etc. In this way, the periphery of a circuit is shielded with a magnetic material, and radiation of a noise can be markedly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a DC-DC converter used for electronic equipment.

[0002]

2. Description of the Related Art FIG. 6 is a perspective view including a partial cross section showing an example of a conventional DC-DC converter. In FIG.
4 is a printed circuit board, 5 is an electric component, 7 is a terminal, 8 is a reactor, and 9 is a shield case. A circuit is formed on a printed circuit board 4, and a reactor 8 or a transformer is mounted as a part of the circuit. In order to reduce radiation noise caused by the reactor 8 or the transformer, the entire circuit is built in a shield case 9.

FIG. 7 is a longitudinal sectional view showing another example of a conventional DC-DC converter. 7, 1 is a ferrite case, 3 is a reactor winding, 10 is a ferrite substrate, and other components are the same as those in FIG. A circuit was formed on a ferrite substrate 10 on which a pattern was printed on ferrite, and a reactor was housed inside.

[0004]

In the case of FIG. 6 of the conventional embodiment, the shielding effect of the shield case may be insufficient, and the radiation effect of the reactor or the transformer mounted on the printed circuit board may cause the circuit to interfere with other circuits. In some cases, it had an adverse effect. In the case of FIG. 7, the ferrite substrate having a pattern printed on the ferrite is difficult to mass-produce and is expensive.

[0005] In addition, in the case of FIG. 7, an appropriate reactor characteristic may not be obtained because the reactor gap is fixed between the ferrite case inner projection and the ferrite substrate. An object of the present invention is to provide an inexpensive DC-DC converter in which radiation noise due to a reactor or a transformer is reduced.

[0006]

In order to solve the above-mentioned problems, in the present invention, a ferrite case and a ferrite plate serve as either a ferrite core of a reactor or a transformer, and a reactor winding, terminals and It has a built-in printed circuit board on which electric components are mounted and a circuit is formed together with conductor wiring.

Further, the ferrite case is surrounded by five ferrite sides and has a projection inside a side opposite to the unenclosed side, and this projection is inserted into one of the windings of the reactor and the transformer. The ferrite plate has a hole for a terminal, and closes an unenclosed side of the ferrite case.

Further, by appropriately selecting the thickness of the printed circuit board or the thickness of the components mounted on the printed circuit board, the reactor or the gap of the transformer can be adjusted to obtain appropriate reactor characteristics (eg, inductance value, DC superimposition characteristic). ) Or transformer characteristics (for example, inductance value, DC superimposition characteristics).

[0009]

FIG. 1 is a perspective view including a partial cross section showing a first embodiment of a DC-DC converter of the present invention, and FIG. 2 is a longitudinal sectional view of FIG. 1 and 2, 2 is a bobbin, 4 is a printed circuit board, 6 is a ferrite plate, and other components are the same as those in FIG. In FIG. 2, the bobbin 2 is omitted.

The printed circuit board 4 is made of, for example, glass epoxy resin, paper phenol resin or the like. The electric component 5 is soldered to one or both sides of the printed circuit board 4. An end of the reactor winding 3 is soldered to a terminal 7 press-fitted and fixed to the bobbin 2, the reactor is mounted on a printed board 4, and the terminal 7 and a conductor wiring on the printed board 4 are soldered. An adhesive is applied to the upper surface of the bobbin 2, and the upper surface of the bobbin 2 is inserted into the ferrite case 1 and bonded. An adhesive is applied to a ferrite plate 6 having a hole for a terminal 7, and the ferrite plate 6 is inserted into the ferrite case 1 so that the terminal 7 passes through the hole for the terminal. Adhere to case 1 and fix.

By mounting a reactor winding 3, terminals 7 and electric parts 5 on a printed circuit board 4, forming a circuit together with conductor wiring, and housing the ferrite case 1 and a ferrite plate 6 which also serve as a ferrite core of the reactor. Since the periphery of the circuit is shielded with a magnetic material, noise radiation can be greatly reduced.

By using a ferrite case which also serves as a ferrite core of the reactor, the number of assembly steps and the cost can be reduced. When a transformer is used, a ferrite case also serving as the ferrite core can be used, and the same as the case of the reactor can be used.

FIG. 3 is a longitudinal sectional view showing a second embodiment of the DC-DC converter according to the present invention. In FIG. 3, the components are the same as those in FIG. 2, and are denoted by the same reference numerals. The thickness of the printed circuit board 4 is the gap of the reactor, and by appropriately selecting the thickness of the printed circuit board 4, the gap of the reactor can be finely adjusted. Characteristic) can be obtained.

FIGS. 4 and 5 show the DC of the present invention, respectively.
It is a longitudinal section showing the 3rd and 4th examples of a -DC converter. 4 and FIG.
And the same reference numerals are used. In this case, the thickness of the printed board 4 plus the thickness of the electrical component 5 is the reactor gap, and the thickness of the printed board 4 and the thickness of the electrical component 5 are appropriately selected. Thus, the gap of the reactor can be finely adjusted, and appropriate reactor characteristics can be obtained.

[0015]

According to the present invention, a printed circuit board is used in place of a ferrite board for mounting an electric component, and the printed circuit board is inserted into the ferrite case and the ferrite plate to shield and reduce radiation noise. Further, since a ferrite substrate on which a pattern is printed is not used, mass production becomes possible, and cost reduction can be realized.

Further, by appropriately selecting the thickness of the printed circuit board and the thickness of the electric components, the gap of the reactor can be finely adjusted, and the range of selection of the reactor characteristics is widened. Production of DC-DC converters becomes possible.

[Brief description of the drawings]

FIG. 1 is a perspective view including a partial cross section showing a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of FIG.

FIG. 3 is a longitudinal sectional view showing a second embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a third embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing a fourth embodiment of the present invention.

FIG. 6 is a perspective view including a partial cross section showing a conventional example.

FIG. 7 is a longitudinal sectional view showing another conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ferrite case, 2 ... Bobbin, 3 ... Reactor winding, 4 ... Printed circuit board, 5 ... Electric components, 6 ... Ferrite plate, 7 ... Terminal.

Claims (3)

[Claims] 1. A structure in which a ferrite case and a ferrite plate also serve as a ferrite core of one of a reactor and a transformer, and a printed circuit board in which reactor windings, terminals, and electric components are mounted, and a circuit is formed together with conductor wiring. DC-DC characterized by the following.
converter. 2. The DC-DC converter according to claim 1, wherein said ferrite case is surrounded by five ferrite sides and has a projection inside a side opposite to the unenclosed side. A DC-DC converter characterized in that a part is inserted into one of a winding of a reactor and a transformer, a ferrite plate has a hole for a terminal, and covers an unenclosed side of the ferrite case. 3. The DC-DC converter according to claim 1, wherein a gap between one of the reactor and the transformer is adjusted by appropriately selecting a thickness of the printed circuit board or a thickness of components mounted on the printed circuit board. And a DC-DC converter characterized by obtaining appropriate reactor characteristics or transformer characteristics.