JPH08222479A - Chip-type capacitor - Google Patents

Abstract

PURPOSE: To provide a chip-type capacitor which is lessened in manufacturing cost and enhanced in uniformity of frequency characteristics. CONSTITUTION: A chip capacitor is equipped with an alumina board 11, a thick film capacitor composed of a pair of a lower electrode 12 and an upper electrode 14 apart from each other through a thick film dielectric layer 13, an Au pad electrode 16a connected to the lower electrode 12, and an Au pad electrode 16b connected to the upper electrode 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip capacitor used especially in a high frequency band.

[0002]

2. Description of the Related Art Conventionally, multilayer capacitors and thin film capacitors have been used as high frequency chip capacitors. In order to manufacture a laminated capacitor, first, a plurality of green sheets are prepared, and internal electrodes are formed on these green sheets. Next, the green sheets are laminated on each other and integrated by thermocompression bonding, and then cut into chips and baked. further,
A desired multilayer capacitor is obtained by forming external electrodes for mounting on a circuit board. To manufacture a thin film capacitor, first, an electrode and a dielectric layer are formed on an alumina substrate by sputtering and pattern etching is performed to obtain a desired thin film capacitor.

[0003]

As described above, the multilayer capacitor is manufactured by forming electrodes on the green sheets, stacking the green sheets on each other to integrate them, and further cutting and firing each chip. There is a problem in that the number of manufacturing steps is large and the manufacturing time is long and the manufacturing cost is increased. Further, when mounting the multilayer capacitor on the circuit board, since the external electrodes and the circuit board are connected by solder, there is a problem that the frequency characteristics of the circuit vary due to variations in the amount of solder in the high frequency band.

Further, since the thin film capacitor is manufactured by sputtering or pattern etching, there is a problem that the manufacturing process is complicated and the manufacturing cost also rises. The present invention has been made in view of the above circumstances, and an object thereof is to provide a chip capacitor in which manufacturing cost is reduced and variation in frequency characteristics is reduced.

[0005]

A chip capacitor according to the present invention which achieves the above object comprises: (1) a ceramic substrate (2) a dielectric layer formed on the ceramic substrate and the dielectric layer interposed therebetween. Thick film capacitor composed of a pair of electrodes separated from each other. (3) A thick film capacitor having a pair of thick film pad electrodes electrically connected to each of the pair of electrodes.

[0006]

The chip capacitor of the present invention has a thick film capacitor and a thick film pad electrode, and these thick film capacitor and thick film pad electrode are formed by the same thick film technique as that for forming a thick film resistor. Easily formed. Therefore, the number of manufacturing steps is smaller and the manufacturing time is shorter than that of the multilayer capacitor, and the manufacturing cost can be reduced as compared with the thin film capacitor without complicated manufacturing steps.

Further, the thick film pad electrode for connecting to the circuit board does not protrude so much as compared with the case where it is formed after cutting each chip like the external electrode of the multilayer capacitor, and the thick film pad electrode of the chip capacitor The influence of the thick film pad electrode on the external size is extremely small. Further, when the thick film pad electrode and the circuit board are connected by wire bonding, the step of attaching the terminal electrode can be omitted, the manufacturing cost can be reduced, and the external electrode of the multilayer capacitor and the circuit board are connected by soldering. Compared with the case, the frequency characteristics of the circuit do not vary in the high frequency band. Further, when the thick film pad electrode is formed in a vertically long shape as in the example described later, it becomes easy to adjust the frequency characteristic in the high frequency band by the wire bonding length, the variation of the frequency characteristic is reduced, and the bonding strength is improved. To do.

[0008]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view of a chip capacitor according to an embodiment of the present invention. Lower electrode 12, dielectric layer 1 on alumina substrate 11
3, an upper electrode 14 is sequentially formed, and thus a pair of lower electrodes 1 are separated from each other by a dielectric layer 13.
2, a capacitor element is formed from the upper electrode 14. Further, an overcoat glass film 15 for protecting the upper electrode 14 and the like is formed on the upper electrode 14.

An Au pad electrode 16a connected to the lower electrode 12 and an Au pad electrode 16b connected to the upper electrode 14 are formed on the overcoat glass layer 15, respectively. These Au pad electrodes 16a, 16
b is wire-bonded to the circuit board.
The method of manufacturing the chip capacitor shown in FIG. 1 will be described below.

FIG. 2 is a diagram showing a manufacturing process of the chip capacitor shown in FIG. Here, an alumina substrate in which scribed grooves are formed at a predetermined pitch in the vertical direction and the horizontal direction is prepared, and a chip capacitor is provided in each area surrounded by the scribed grooves of the alumina substrate before being divided by the scribed grooves. Form. First, a conductive paste is printed by a screen printing method on an alumina substrate 11 (which means each region surrounded by the scribe groove before being divided by the scribe groove) shown in FIG. Formed.

Next, as shown in FIG. 2B, a dielectric paste was printed on the lower electrode 12 by screen printing and baked to form a dielectric layer 13. Next, FIG.
As shown in (c), a conductor paste is printed on the dielectric layer 13 by a screen printing method and baked to form the upper electrode 1.
4 was formed. Next, as shown in FIG. 2D, a glass paste was printed so as to cover the upper electrode 14 and the like and baked to form an overcoat glass layer 15.

Further, as shown in FIG. 2E, the upper electrode 1 is electrically connected to the lower electrode 12 and spreads over a part of the overcoat glass layer 15.
No. 4 is electrically connected to No. 4 and is spread on a portion of the overcoat glass layer 15 by printing an Au thick film paste by a screen printing method and firing to form Au pad electrodes 16a and 16b for wire bonding. did.

After that, the alumina substrate was cut along the scribe groove to divide it into chips. As shown in FIG. 2E, the Au pad electrodes 16a and 16b connected to the lower electrode 12 and the upper electrode 14, respectively, are extended to above the overcoat glass layer 15, and the frequency characteristic in the high frequency band due to the wire bonding length is obtained. Is easy to adjust, and the bonding strength to the lower electrode 12 and the upper electrode 14 is also improved.

Although an alumina substrate is used as the base substrate in this embodiment, the chip capacitor of the present invention does not necessarily have to use an alumina substrate, and other ceramic substrates may be used. Good.

[0015]

As described above, the chip capacitor of the present invention has the thick film capacitor and the thick film pad electrode, and these thick film capacitor and thick film pad electrode are manufactured by the thick film technology. Therefore, the manufacturing cost can be reduced. Further, if the thick film pad electrode and the circuit board are connected by wire bonding and the thick film pad electrode is formed in a vertically long shape as in the above-mentioned embodiment, the frequency characteristic in the high frequency band can be easily adjusted by the wire bonding length. ,
Variations in frequency characteristics are reduced and bonding strength is improved.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a manufacturing process of the chip capacitor shown in FIG.

[Explanation of symbols]

 11 Alumina Substrate 12 Lower Electrode 13 Dielectric Layer 14 Upper Electrode 15 Overcoat Glass Layer 16a, 16b Au Pad Electrode

Claims (1)

[Claims] 1. A thick film capacitor comprising a ceramic substrate, a dielectric layer formed on the ceramic substrate, and a pair of electrodes separated from each other by the dielectric layer, and an electrical connection to each of the pair of electrodes. A chip capacitor having a pair of thick film pad electrodes that are electrically connected to each other.