JPH07307245A - Chip capacitor - Google Patents

Abstract

PURPOSE:To provide a chip capacitor whose capacitance shows little variation against the variation of an ambient temperature and which is small in size. CONSTITUTION:A resistance element 13 which is stuck to one of the surfaces of a dielectric 11 between a pair of outer electrodes 12a and 12b and which has a positive resistance-temperature coefficient and a pair of terminal plates 14b which face each other with the resistance element 13 therebetween in a direction perpendicular to the facing direction of the pair of the outer electrodes 12a and 12b are provided. The pair of the outer electrodes 12a and 12b and the pair of the terminal plates 14b are exposed on a same surface. The temperature of the dielectric 11 can be maintained at a required value regardless of an ambient temperature such as the open air temperature by the resistance element 13 and hence the dielectric constant of the dielectric can be maintained at a required value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip capacitor which has an external electrode integrally provided on a dielectric and is used by directly bonding the external electrode to a circuit board, and particularly to a relatively high dielectric constant. Of chip capacitors.

[0002]

2. Description of the Related Art Chip capacitors are widely used as capacitors suitable for mass production of small resonant circuits and the like because they are small and can be easily joined to a circuit board by using a machine. . By the way, the dielectric constant of the dielectric, which is one of the elements of the electrostatic capacity of the capacitor, tends to rise and fall due to changes in the ambient temperature. In particular, as described in JP-A-60-120510,
Since the monolithic ceramic type chip capacitor provided with the internal electrodes has a high dielectric constant, the change in capacitance due to the change in ambient temperature is large.

[0003]

As described above, since the capacitance of the conventional chip capacitor depends on the environmental temperature change, the characteristics of the electric circuit using the same are also affected by the environmental temperature change. There is a problem that it ends up. Therefore, a chip capacitor having stable characteristics with a small change in capacitance due to a change in environmental temperature is desired.

An object of the present invention is to provide a chip capacitor having a small change in capacitance with respect to a change in environmental temperature.

[0005]

According to the present invention, in a chip capacitor having a dielectric body and a pair of external electrodes facing each other with the dielectric body sandwiched therebetween, the dielectric body is provided between the pair of external electrodes. A resistor having a positive temperature coefficient of resistance and a pair of terminal portions facing each other at right angles to the facing direction of the pair of external electrodes, the pair of external electrodes and A chip capacitor is obtained in which the terminal portions of the pair are exposed on the same surface. Further, the resistor preferably comprises BaTiO ₃ ceramics as a main material.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A chip capacitor according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a monolithic ceramic type chip capacitor according to this embodiment. Figure 2
FIG. 3 is a vertical cross-sectional view of a cut surface parallel to the facing direction of a pair of external electrodes in the chip capacitor shown in FIG. 1. Figure 3
FIG. 2 is a vertical cross-sectional view taken along a cutting plane perpendicular to a facing direction of a pair of external electrodes in the chip capacitor shown in FIG. 1.

1 to 3, the chip capacitor 1
Reference numeral 0 denotes a dielectric 11 made of ceramic, and a plurality of internal electrodes 12c provided in the dielectric 11 in parallel with each other.
A resistor 13 which is joined to the lower surface of the dielectric 11 in the figure and whose resistance value changes according to its own temperature, is joined to both ends of the joined body of the dielectric 11 and the resistor 13, and is electrically connected to the internal electrode 12c. External electrodes 12a and 12b, and terminal plates 14a and 14b that are terminal portions provided at both ends of the resistor 13 so as to be orthogonal to the facing direction of the external electrodes 12a and 12b. External electrodes 12a and 12b
The terminals 14a and 14b are exposed on the same surface (the lower surface in the figure) of the chip capacitor 10.

The resistor 13 is composed of a thermistor (PTC thermistor) having a positive temperature resistance characteristic. As the PTC thermistor, it is preferable to use BaTiO ₃ ceramics as a main material in terms of the linearity of the temperature resistance characteristic and the temperature range.

FIG. 4 is an equivalent circuit diagram of the chip capacitor shown in FIGS. In FIG. 4, the capacitor C includes a dielectric 11, outer electrodes 12a and 12b, and an inner electrode 1.
2c, and the resistor R is a resistor 13 and a terminal plate 14a.
And 14b. The capacitor C and the resistor R are electrically independent.

Next, the operation of the chip capacitor 10 will be described.

The chip capacitor 10 has its resistor 13
The external electrodes 12a and 12b and the terminal plates 14a and 14b are soldered with their sides facing a circuit board (not shown), so that they are joined to the circuit board. Here, it is assumed that the circuit board constitutes a resonance circuit. The resonance circuit has a resonance circuit section and a voltage application section for applying a predetermined voltage to the resistor 13. The external electrodes 12a and 12b are connected to the resonance circuit section, while the terminal plates 14a and 14b are connected to the voltage applying section.

When the operation of the resonance circuit section is started and a predetermined voltage is applied between the terminal plates 14a and 14b by the voltage application section, a current flows through the resistor 13 and the resistor 13 generates heat. To do. Then, the dielectric 11 joined to the resistor 13 is heated. More specifically, when the resistor 13 itself has a low temperature, its resistance value is low and a large amount of current flows. Therefore, the heat generated by the resistor 13 is increased, and the dielectric 11 is heated. On the other hand, the resistance value of the resistor 13 that has been heated by the flow of a large amount of current increases and the current decreases. Therefore, the heat generated by the resistor 13 is reduced, and the temperature of the dielectric 11 does not rise above the predetermined temperature.

Therefore, the dielectric 11 maintains a predetermined temperature and the dielectric constant also a predetermined value due to the above-mentioned heat generation effect of the resistor 13 regardless of the environmental temperature such as the outside air temperature. Therefore, the resonance circuit to which the chip capacitor 10 is connected can also maintain characteristics such as a predetermined resonance frequency.

[0015]

Since the chip capacitor according to the present invention has the resistor having a positive temperature coefficient of resistance joined to one surface of the dielectric, the change in capacitance with respect to the change in environmental temperature is small. That is, it has excellent temperature characteristics.

The resistor is bonded to one surface of the dielectric between the pair of external electrodes, and the ends of the pair of resistors face each other at right angles to the facing direction of the pair of external electrodes. Since the terminal portion of is exposed on the same surface, it is small like the conventional chip capacitor, and the bonding process to the circuit board is not changed.

The electronic circuit in which the chip capacitor according to the present invention is inserted does not easily change its capacitance, which is one of the factors of its characteristics, depending on the ambient temperature, so that stable characteristics can be obtained, and it is small and assembled. Is easy.

[Brief description of drawings]

FIG. 1 is a perspective view showing a chip capacitor according to an exemplary embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a cut surface parallel to the facing direction of a pair of external electrodes in the chip capacitor shown in FIG.

FIG. 3 is a vertical cross-sectional view taken along a cross section perpendicular to the facing direction of a pair of external electrodes in the chip capacitor shown in FIG.

FIG. 4 is an equivalent circuit diagram of the chip capacitor shown in FIG.

[Explanation of symbols]

 10 Chip Capacitor 11 Dielectric 12a, 12b External Electrode 12c Internal Electrode 13 Resistor 14a, 14b Terminal Plate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01G 4/258

Claims (2)

[Claims] 1. A chip capacitor having a dielectric and a pair of external electrodes facing each other with the dielectric interposed therebetween, wherein a positive temperature coefficient of resistance is provided on one surface of the dielectric between the external electrodes of the pair. And a pair of terminal portions that face each other at right angles to the facing direction of the pair of external electrodes with the resistor interposed therebetween, and the pair of external electrodes and the pair of terminal portions are on the same surface. A chip capacitor characterized by being exposed. 2. The chip capacitor according to claim 1, wherein the resistor is mainly made of BaTiO ₃ ceramics.