JPH09215324A - Dc-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a layered ceramic part which may be manufactured at a low cost without generation of cracks of laminated material and deterioration of electrical characteristic. SOLUTION: A DC-DC converter 10 includes a laminated material 11, electronic parts 12, for example, an integrated circuit for control, a coil, a transistor, a diode, etc., are anointed on the laminated material 11 by connecting these elements on a circuit pattern 13 by solder and the laminated material 11, the electronic parts 12 and circuit pattern 13 are covered with a metal case 14. the laminated material 11 laminates and sinters a dielectric material layer 15 having the specific dielectric coefficient of several thousands and an internal electrode layer 15 formed of nickel and comprises therein an input smoothing capacitor Cin and output smoothing capacitor Cout. In this case, the internal electrode layer 16b located at the upper most layer and lower most layer of the internal electrode layer 16 is grounded as a ground electrode layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-DC converter, and more particularly to a DC-DC converter using a laminated body having a built-in capacitor function.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a basic circuit of a DC-DC converter, and FIG. 5 shows a sectional view of a conventional DC-DC converter. The DC-DC converter 50 includes a laminated body 51, and an electronic component 52, for example, a control circuit C, a coil L, a transistor Tr, a diode D in FIG.
Are mounted on the laminated body 51 by connecting them to the circuit pattern 53 with solder or the like, and the electronic component 52 and the circuit pattern 53 are covered with a metal case 54.

6 and 7 are an exploded perspective view and a bottom view of the laminated body 51. The laminated body 51 is formed by laminating and sintering a dielectric layer 55 having a relative permittivity of several hundred to several thousand and an internal electrode layer 56 made of palladium (Pd), silver-palladium (Ag-Pd), or the like, by a green sheet laminating method. Then, the capacitor function, that is, the input smoothing capacitor Cin and the output smoothing capacitor Cout are internally configured. At this time, the dielectric layer 55 and the internal electrode layer 56 are repeatedly laminated until the required capacitance is obtained. Thereafter, the shield electrode 57, the dielectric layer 55a, the circuit pattern 53, and the dielectric layer 55a are sequentially formed on the surface of the laminated body 51 after sintering by the thick film printing method.
External terminals 58a to 58 formed on the side surface and the lower surface of the
Sinter with f.

The external terminals 58a and 58b serve as the input terminal Vin and the output terminal Vout, and the internal electrode layer 56 is formed.
The internal electrode layer 56a is connected to the external terminal 58e,
58f serves as a ground terminal GND, and the ground electrode layer 56b of the internal electrode layers 56 is connected thereto.

At this time, the internal electrode layer 56a and the ground electrode layer 56b are formed on the surface of the dielectric layer 55, as shown in FIG. 6, for the input smoothing capacitors Cin 561a, 561b, and 561b.
The output smoothing capacitors Cout 562a and 562b are printed separately.

An input smoothing capacitor Cin is provided between the internal electrode layer 561a connected to the external terminal 58a and the ground electrode layer 561b connected to the external terminal 58e, and the internal electrode layer 562a connected to the external terminal 58b and the outside. The output smoothing capacitor Cout is formed between the ground electrode layers 562b connected to the terminal 58f. The shield electrode 57 is electrically connected to the ground electrode layer 56b.

[0007]

However, in the above-mentioned conventional DC-DC converter, the thick film multilayer printing is used to form the shield electrode on the surface of the laminated body after sintering, so that the thick film multilayer printing is performed. There is a problem that the number of times increases and the manufacturing cost increases. In addition, when the number of times of thick film multi-layer printing increases, a slight difference in heat shrinkage between the laminate and the thick film paste or crystallization of the thick film paste accumulates as stress. There is a problem that cracks occur in the.

Further, when palladium is used for the internal electrode layers, there is a problem that the manufacturing cost becomes high.
Also, when silver-palladium is used, the manufacturing cost is reduced to some extent, but since the series equivalent resistance of the built-in capacitor increases, ripple noise
Becomes large and the electrical characteristics of the DC-DC converter deteriorate.

The object of the present invention is to solve such problems, and DC-manufacturing is possible at low cost without causing cracks and deterioration of electric characteristics of the laminate.
It is to provide a DC converter.

[0010]

In order to solve the above problems, the present invention provides a surface of a laminated body having a plurality of capacitor functions, which is formed by laminating and sintering a plurality of internal electrode layers and a plurality of dielectric layers. A circuit pattern is formed on the substrate, the internal electrode layer and the circuit pattern are electrically connected, and at least one electronic component is electrically connected to the circuit pattern.
In the C-DC converter, among the internal electrode layers having the plurality of capacitor functions, the uppermost layer or the internal electrode layers located at the uppermost layer and the lowermost layer are connected to the ground to form a ground electrode layer. .

The ground electrode layer may be commonly used among the plurality of capacitor functions to form a common ground electrode layer.

Further, the common ground electrode layer is drawn out from at least two side surfaces of the laminated body, and the laminated body has a cross section of a top surface and side surfaces formed downward from four end portions of the top surface. It is characterized in that the common ground electrode layer and the metal case are electrically connected to each other so that the inside of the side surface of the metal case comes into contact with the side surface of the laminated body in the character-shaped metal case.

Further, it is characterized in that a base metal is used for the internal electrode layers.

According to the DC-DC converter of the first aspect, among the internal electrode layers having a plurality of capacitor functions incorporated in the laminated body, the uppermost layer or the internal electrode layers located at the uppermost layer and the lowermost layer are grounded. With the electrode layer,
The innermost electrode layer, that is, the ground electrode layer disposed on the uppermost layer or the uppermost layer and the lowermost layer, can be used as the shield electrode.

According to the DC-DC converter of the second aspect, the ground electrode layer is a common ground electrode layer common to a plurality of capacitor functions, so that the wiring resistance can be reduced.

According to the DC-DC converter of claim 3, the common ground electrode layer is provided on at least two side surfaces of the laminate.
The wiring resistance can be further reduced because it is pulled out from several places and connected to the metal case.

According to the DC-DC converter of the fourth aspect, since the base metal is used for the capacitor electrode, the manufacturing cost can be reduced while maintaining the electrical characteristics.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an embodiment of a DC-DC converter according to the present invention. Here, DC-
A circuit diagram as shown in FIG. 4 is given as an example of the basic circuit of the DC converter.

The DC-DC converter 10 is a laminated body 1
1, the electronic component 12, for example, the integrated circuit IC for control circuit, the coil L, the transistor Tr, the diode D, etc. in FIG. A metal case 1 made of copper or the like for the body 11, the electronic component 12, and the circuit pattern 13.
It is configured by covering with 4.

2 and 3 show an exploded perspective view and a bottom view of the laminated body 11. The laminated body 11 is formed by laminating and sintering a dielectric layer 15 having a relative permittivity of several hundred to several thousand and an internal electrode layer 16 made of a base metal such as nickel (Ni) by a green sheet laminating method to obtain a capacitor function, that is, The input smoothing capacitor Cin and the output smoothing capacitor Cout are internally configured. At this time, the dielectric layer 15 and the internal electrode layer 16 are repeatedly laminated until the required capacitance is obtained. Then, the dielectric layer 15 is formed on the surface of the laminated body 11 after sintering by a thick film printing method.
a, the circuit pattern 13, the dielectric layer 15a, and the circuit pattern 13 are sequentially formed and sintered together with the plurality of external terminals 17a to 17f formed on the side surface and the lower surface of the laminated body 11.

The external terminals 17a and 17b become the input terminal Vin and the output terminal Vout, and the internal electrode layer 16
Internal electrode layer 16a is connected to the external terminal 17c
To 17f become the ground terminal GND, and the internal electrode layer 16
Of these, the common ground electrode layer 16b is connected.

At this time, as shown in FIG. 1, the internal electrode layer 16 is formed by laminating a common ground electrode layer 16b and an internal electrode layer 16a in this order, and the common ground electrode layer 16b is the uppermost layer and the lowermost layer of the internal electrode layer 16. Is formed so as to be located at.
Further, the circuit pattern 13 and the internal electrode layer 16 are connected by the external terminals 17a to 17f.

The internal electrode layer 16a is formed on the surface of the dielectric layer 15 as shown in FIG.
161a for in, 162 for output smoothing capacitor Cout
Printed separately from a.

Further, the common ground electrode layer 16b is formed as shown in FIG.
As shown in FIG. 3, the input smoothing capacitor Cin and the output smoothing capacitor Cou are solid printed on the surface of the dielectric layer 15.
It is common at t.

Further, as shown in FIG. 2, the common ground electrode layer 16b is drawn out from the four sides to the side surface of the laminated body 11 and serves as the ground terminals GND.
connected to f. Further, the external terminals 17c and 17d and the metal case 14 are electrically connected by soldering or the like.

The input smoothing capacitor C is provided between the internal electrode layer 161a connected to the external terminal 17a and the common ground electrode layer 16b connected to the external terminals 17c to 17f.
in is an internal electrode layer 162 connected to the external terminal 17b
An output smoothing capacitor Cout is formed between a and the common ground electrode layer 16b connected to the external terminals 17c to 17f.

Here, when copper, which is a diamagnetic material, is used for the metal case as in the above-described embodiment, the magnetic field generated around the coil is less likely to magnetize,
Excessive energy is not consumed, and it is possible to suppress a decrease in conversion efficiency for converting input power to output power.

In the above embodiment, DC-D
Although the case where only the smoothing capacitor of the C converter is built in the laminated body has been described, other capacitors necessary for the circuit may be built in.

Although the case where the uppermost layer and the lowermost layer are provided as the ground electrode has been described, the ground electrode may be provided at least in the uppermost layer.

Further, the case where the circuit pattern is formed on the laminated body through the dielectric layer for the purpose of improving the laser trimming property when forming the thin film resistor has been described.
The circuit pattern may be directly formed on the laminate.

Further, although the case where the external terminal is used for the connection between the circuit pattern and the internal electrode layer has been described, a via hole or a through hole may be formed inside the laminated body, and the via hole or the through hole may be used for connection.

Further, although the case where the internal electrode layers serving as the ground electrode and the shield electrode are drawn out to the side surface of the laminated body at four positions is shown, it may be drawn out from any number of positions as long as it is two or more positions.

Although the case where all the ground electrodes are the common ground electrodes is shown, the ground electrodes not arranged on the uppermost layer of the internal electrode layers or on the uppermost layer and the lowermost layer are not common ground electrodes. Good.

Further, although the case where nickel is used as the base metal has been described, any base metal having a series equivalent resistance similar to that of palladium may be used.

The present invention is not limited to the DC-DC converter of the basic circuit shown in FIG. 4, and may be used for any DC-DC converter having a built-in capacitor.

[0036]

According to the DC-DC converter of the first aspect, among the internal electrode layers having a plurality of capacitor functions incorporated in the laminated body, the internal electrode layers located at the uppermost layer or the uppermost layer and the lowermost layer are located. With the ground electrode as
The innermost electrode layer, that is, the ground electrode layer disposed on the uppermost layer or the uppermost layer and the lowermost layer, can be used as the shield electrode. Therefore, since the ground electrode and the shield electrode are commonly used, the number of times of printing and the number of times of firing can be reduced. In addition, the manufacturing cost can be reduced and the quality can be stabilized.

According to the DC-DC converter of the second aspect, the ground electrode layer is common to a plurality of capacitor functions and is a common ground electrode layer, so that the wiring resistance can be reduced. Therefore, the ground is strengthened, ripple noise is reduced, and good electrical characteristics are obtained.

According to the DC-DC converter of claim 3, the common ground electrode layer is provided on at least two side surfaces of the laminate.
By pulling out from several places and connecting with a metal case,
The wiring resistance can be further reduced. Therefore, the ground is further strengthened, ripple noise is further reduced, and more favorable electric characteristics are obtained.

Further, since the lowermost layer of the internal electrode layers serves as the ground electrode layer and the metal case is also connected to the ground, the DC-DC converter itself has a shield structure so that it does not affect others. .

According to the DC-DC converter of the fourth aspect, since the base metal is used for the capacitor electrode, the unit cost of the material becomes low and the manufacturing cost can be greatly reduced.

Further, the ripple noise is similar to that of conventional palladium, and good electrical characteristics with low ripple noise can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a DC-DC converter according to the present invention.

FIG. 2 is an exploded perspective view of a laminated body that constitutes the DC-DC converter of FIG.

FIG. 3 is a plan view of a laminated body that constitutes the DC-DC converter of FIG.

FIG. 4 is a circuit diagram showing an example of a basic circuit of a DC-DC converter.

FIG. 5 is a sectional view of a conventional DC-DC converter.

6 is an exploded perspective view of a laminated body that constitutes the DC-DC converter of FIG.

FIG. 7 is a plan view of a laminated body that constitutes the DC-DC converter of FIG.

[Explanation of symbols]

10 DC-DC converter 11 Laminated body 12 Electronic component 13 Circuit pattern 15 Dielectric layer 16 (16a, 16b) Internal electrode layer Cin, Cout Capacitor function (smoothing capacitor)

Claims (4)

[Claims] 1. A circuit pattern is formed on the surface of a laminate having a plurality of capacitor functions, which is formed by laminating and sintering a plurality of internal electrode layers and a plurality of dielectric layers, and the internal electrode layers and the circuit pattern are formed. Electrically connected to at least 1
In a DC-DC converter in which two electronic components are electrically connected to the circuit pattern, among the internal electrode layers having the plurality of capacitor functions,
A DC-DC converter characterized in that the uppermost layer, or the internal electrode layers located at the uppermost layer and the lowermost layer are connected to the ground to form a ground electrode layer. 2. The DC-DC converter according to claim 1, wherein the ground electrode layer is shared by the plurality of capacitor functions to form a common ground electrode layer. 3. The common ground electrode layer is drawn out from at least two positions on the side surface of the laminate, and the laminate is
In a metal case having a substantially U-shaped cross section formed of an upper surface and side surfaces formed below the four ends of the upper surface, the metal case is inserted so that the inside of the side surface contacts the side surface of the laminate. The DC-D according to claim 2, wherein the common ground electrode layer and the metal case are electrically connected.
C converter. 4. The DC-DC converter according to claim 1, wherein a base metal is used for the internal electrode layers.