JPH04357806A - Surface mounting porcelain capacitor - Google Patents

Abstract

PURPOSE:To provide a surface mounting porcelain capacitor which can be mounted at a high density so as to enable electronic apparatuses to be smaller and thinner. CONSTITUTION:The titled capacitor is composed of a dielectric porcelain substrate 17 of rectangular parallelopiped shape whose square parts are chambered, a pair of square electrodes 19 that are placed around the center section on two main planes 18 of the substrate 17 and of which respective corners are circular, lead terminals 20 having intercepts connected to respective electrodes 19, and an outer jacksting material 21 which cover the substrate 17, an entire surface of the electrodes 19 and the surface of the terminals 20 other than the surface of external connection terminal of the terminals 20.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is mainly used for medium and high voltage circuits such as horizontal resonant circuits, AC noise prevention circuits, rectifier circuits, etc. of general electronic equipment, power supply equipment, etc., and is suitable for surface mounting, which is effective for making equipment thinner. It concerns ceramic capacitors.

0002

2. Description of the Related Art In recent years, radial lead type disc-shaped medium-high voltage porcelain capacitors have been used in high voltage circuits of electronic equipment. However, in recent years, as electronic devices have become smaller and thinner, switching power supplies have also become smaller and thinner, and along with this, surface mounting has progressed and the rate of chip-based components has also increased. In line with these trends in the electronic equipment industry, multilayer chip type medium and high voltage ceramic capacitors have been developed.

[0003] A conventional surface-mounted ceramic capacitor will be explained below. FIG. 4 is a partially cutaway perspective view of a conventional radial type ceramic capacitor.

1 is a disc-shaped dielectric ceramic substrate (hereinafter referred to as a circular substrate), 2 is an electrode made of silver, copper, zinc, nickel, etc. formed on both sides of the circular substrate 1, and 3 is a lead drawn out from the electrode 2. Terminal 4 is the exterior.

FIG. 5 is a perspective view of a conventional multilayer chip type ceramic capacitor. 5 is a square dielectric ceramic substrate (hereinafter referred to as a square substrate), 6 is an internal electrode coated on the surface of the square substrate 5 and laminated together with the square substrate 5, and 7 is an external electrode.

The mounting state of the conventional ceramic capacitor constructed as described above will be described below.

FIG. 6 is a partial cross-sectional side view showing a state in which a radial lead type ceramic capacitor and other components are mounted on a printed circuit board, and FIG. 7 shows a state in which a multilayer chip type magnetic capacitor is mounted on a printed circuit board. FIG. 3 is a partially sectional side view. In FIG. 6, reference numeral 8 denotes a printed circuit board, and lead terminals 12 of a radial type ceramic capacitor 9 and other components 10 and 11 are attached to the printed circuit board 8 with solder 13. Further, in FIG. 7, reference numeral 14 denotes a multilayer chip type ceramic capacitor, which is mounted by attaching external electrodes 15 provided at both ends to the printed circuit board 8 with solder 16.

[0008]

However, in the conventional configuration described above, when a radial lead type ceramic capacitor is mounted on a printed circuit board, the height of the magnetic capacitor increases by the diameter of the circular circuit board. When mounted on a device, there was a problem in that it hindered the thinning of the device. In addition, although multilayer chip type ceramic capacitors are effective in making them thinner, the dielectric layer that contributes to withstand voltage is thin, making it difficult to guarantee safety standards, and the electrode material Since precious metals such as palladium are used as the material, there are problems in that the cost increases and it is not suitable for mass production.

The present invention solves the above-mentioned conventional problems, and aims to provide a surface-mounted ceramic capacitor that is effective in reducing the size and thickness of electronic equipment and enables high-density packaging. It is.

0010

[Means for Solving the Problems] In order to achieve this object, the surface-mounted ceramic capacitor of the present invention includes a single dielectric ceramic substrate with chamfered square parts of a rectangular parallelepiped, and a surface of the dielectric ceramic substrate. A pair of rectangular square parts formed on the plane of the back surface have a radius of curvature R of at least 1 mm, and two L-shaped electrodes each having a section electrically connected to a part of each of the pair of electrodes. Consists of a lead terminal and
The entire surface of the dielectric ceramic substrate, the electrode, and the surface of the lead terminal except for the terminal surface for external connection is covered with an exterior material.

[0011]

[Function] With this configuration, the height of the ceramic capacitor can be reduced while having the same withstand voltage as a conventional disk-type ceramic capacitor for medium and high voltages, eliminating wasted space between it and the printed circuit board. This makes it possible to make electronic devices thinner.

Furthermore, since the rectangular parallelepiped dielectric ceramic substrate is formed by chamfering the shortest square part, it is possible to receive the dielectric ceramic substrate with uniform density, and the square part of the rectangular electrode has no curvature. Since the radius R is provided, lines of electric force concentrated at the corners of the electrode can be dispersed, and variations in breakdown voltage can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view of a surface-mounted ceramic capacitor according to an embodiment of the present invention, FIG. 2 is a cross-sectional side view thereof, and FIG. 3 shows an L-shaped lead formed in a substantially L-shape. It is a terminal.

17 is a single dielectric ceramic substrate (hereinafter referred to as a single substrate) having a rectangular parallelepiped with chamfered square parts; 18 is a single substrate 1;
7 main plane, 19 is an electrode with a radius of curvature R on a rectangular square part formed on the front and back surfaces of the two main planes 18;
Reference numeral 20 denotes L-shaped lead terminals connected to the electrodes 19, which are provided on both sides of the single substrate 17. Note that 21 is a protective exterior material.

A method of manufacturing the surface-mounted ceramic capacitor of this embodiment constructed as described above will be explained below. Barium titanate and several types of additives are mixed and dried using ordinary ceramic techniques, granulated using a binder such as polyvinyl alcohol, and then sized to a particle size that can pass through a 32-mesh sieve. After that, the sized powder is 10mm x 23m
m, thickness of 4 mm, radius of curvature R of 3 mm, approximately 1
The molded body was molded with a pressure of ton/cm2, and the molded body was fired at a temperature of 1300 to 1400°C in the atmosphere to form a 8 mm×
A single substrate 17 having a diameter of 20 mm, a thickness of approximately 3 mm, and a radius of curvature R of 2 mm is obtained. A silver paste was applied to each main plane 18 of this single substrate 17, dried, and baked in the air at a temperature of 800°C for about 5 minutes to obtain a size of 7 mm x 19 mm with a radius of curvature R of 2.
An electrode 19 of mm is formed. After connecting the pieces 20a of the L-shaped lead terminals 20 shown in FIG. 3 with conductive paste so that they are in contact with parts of the electrodes 19 on both sides of the ceramic capacitor obtained in this way,
L into a horizontally split mold (not shown) with a depth of 6 mm and cast a resin such as epoxy as the exterior material 21.
By covering the mold lead terminal 20 except for the terminal surface for external connection, a surface-mounted ceramic capacitor can be manufactured.

Next, the capacitance is 1000, 2200, 3
A 300 pF surface mount ceramic capacitor was manufactured, and its size and DC breakdown voltage (KV) were measured. The results are shown in (Table 1).

(Comparative Examples 1 and 2) A conventional radial lead type disc-type medium-high voltage porcelain capacitor (Comparative Example 1) and a laminated type medium-high voltage porcelain capacitor (Comparative Example 1) having the same capacitance as the example Example 2) were manufactured, and their sizes and DC breakdown voltages (KV) were measured under the same conditions as in Examples. The results are shown in (Table 1).

[0019]

[Table 1]

As is clear from this (Table 1), the higher the capacitance of conventional radial lead type ceramic capacitors, the higher the mounting height, which is a factor that hinders the thinning of electronic devices. Recognize. Furthermore, although the stacked type has small dimensions and can be mounted at high density, it has a problem that it has a low DC breakdown voltage and cannot cope with higher voltage power supplies. It can be seen that the surface-mounted ceramic capacitor of this example has a well-balanced size and DC breakdown voltage, and can sufficiently respond to thinner electronic devices and higher voltage power supplies.

Next, the average value and minimum value of the breakdown voltage were measured according to a conventional method when the radius of curvature R applied to the dielectric ceramic substrate and the electrode was varied.

The results are shown in (Table 2).

[0023]

[Table 2]

As is clear from Table 2, by providing a radius of curvature R to the dielectric ceramic substrate and the electrode, the variation in DC breakdown voltage is reduced. especially,
The effect is significant when the electrode has a radius of curvature R of 1 mm or more. This is because if a dielectric ceramic substrate has corners, the pressure distribution at the corners will be uneven during molding, making it impossible to obtain a high-quality dielectric ceramic substrate.Also, if an electrode has corners, electricity will be generated at the corners. Since the lines of force are concentrated, the breakdown voltage decreases and the variation increases, but this is thought to be because by adding the radius of curvature R, the pressure distribution during molding becomes uniform and a high-quality dielectric ceramic substrate can be obtained. Also, since the electric lines of force at the corners of the electrode are evenly distributed,
This is thought to be because the variation in DC breakdown voltage becomes smaller.

According to the embodiment described above, the electrode 19 having a rectangular square portion with a radius of curvature R is formed on the main plane 18 of the single substrate 17 whose square portions are chamfered. L such that the section 20a is connected to each section.
Because the type lead terminal 20 is provided, it has a DC breakdown voltage equivalent to that of a conventional radial lead type ceramic capacitor, and also reduces the variation in the DC breakdown voltage while reducing the mounting height. Since it has a type lead terminal structure, there is no wasted space between it and the printed circuit board, making it possible to achieve thinner electronic devices and higher density packaging.

[0026]

As described above, the present invention connects L-shaped lead terminals to electrodes formed on the main plane of a chamfered single-plate ceramic capacitor and having a radius of curvature R at the corner. It has a DC breakdown voltage equivalent to that of conventional disk-shaped ceramic capacitors, while allowing for a lower mounting height.Furthermore, the L-shaped lead terminal shape allows surface mounting directly onto a printed circuit board. This makes it possible to create excellent surface-mount ceramic capacitors that do not create wasted space between the printed circuit board and components, making it possible to make electronic devices such as switching power supplies thinner and more densely packaged. It is.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a surface-mounted ceramic capacitor according to an embodiment of the present invention.

[Fig. 2] A vertical cross-sectional view of a surface-mounted ceramic capacitor in an embodiment of the present invention.

[Fig. 3] A perspective view of an L-shaped lead terminal in one embodiment of the present invention.

[Figure 4] Partially cutaway side view of a conventional radial lead type ceramic capacitor

[Figure 5] Perspective view of a conventional multilayer chip type ceramic capacitor

[Figure 6] Partial cross-sectional side view showing a conventional radial lead type ceramic capacitor mounted on a printed circuit board.

[
Figure 7: Partial cross-sectional side view showing a conventional multilayer chip type ceramic capacitor mounted on a printed circuit board

[Explanation of symbols] 17 Dielectric ceramic substrate 18 Main plane 19 Electrode 20 Lead terminal 20a Section 21 Exterior material

Claims (1)

[Claims] 1. A dielectric ceramic substrate in the shape of a rectangular parallelepiped with a chamfered square portion, and a pair of square portions disposed approximately in the center of the front and back surfaces of the dielectric ceramic substrate, the square portion being formed in an arc shape. a lead terminal having an electrode and a piece connected to each electrode;
A surface-mounting ceramic capacitor comprising the dielectric ceramic substrate and an exterior material that covers the entire surface of the electrode and the surface of the lead terminal except for the external connection terminal surface of the lead terminal.