JPH039605B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a trimming capacitor used, for example, in a crystal oscillation circuit in a crystal oscillation wristwatch.

When adjusting the rate of a crystal oscillation wristwatch by adjusting the oscillation frequency of the crystal oscillation circuit, conventionally a trimmer capacitor is used as a variable capacitance capacitor, and by variably adjusting the capacitance value of this trimmer capacitor, the oscillation frequency can be adjusted. I tried to adjust it.

However, trimmer capacitors have mechanically movable parts, and after capacitance adjustment, the capacitance value tends to change due to vibrations, etc. This causes problems such as fluctuations in the oscillation frequency, resulting in a lack of reliability and frequency stability. It was hot. In addition, due to its structure, the trimmer capacitor
There are limits to miniaturization and thinning, which makes it difficult to achieve high-density packaging, and it also has the disadvantage of increasing costs.

In order to eliminate these drawbacks of trimmer capacitors, trimming capacitors having trimmable electrodes have been proposed. This trimming capacitor, as illustrated in FIG.
A dielectric ceramic layer 1A is provided with a trimming electrode 2 and has an appropriate layer thickness from the surface on which the trimming electrode 2 is formed.
while embedding the internal electrode 3 through the trimming electrode 2 and the opposite ends of the internal electrode 3,
It had a structure in which end electrodes 4 and 5 provided on opposite surfaces of the ceramic substrate 1 were electrically connected to each other.

In order to incorporate the trimming capacitor of the above structure into a crystal oscillation circuit of a wristwatch or the like to adjust the capacitance and frequency, as shown in FIG. The above-mentioned trimming capacitor 9 is soldered onto the printed circuit board of the crystal oscillator circuit to be constructed so that the end electrodes 4 and 5 are electrically connected to one end of each of the crystal resonator 6 and the fixed capacitor 7. The area of the trimming electrode 2 exposed on the surface is reduced to a desired capacitance value and oscillation frequency. After adjusting the capacitance by electrode trimming, the trimming capacitor 9 becomes a fixed capacitor, so unlike conventional trimmer capacitors, it does not cause changes in capacitance or fluctuations in oscillation frequency, resulting in high reliability and good frequency stability. A crystal oscillation circuit can be realized. Furthermore, since it is chip-shaped, it is small and thin, making it easy to implement high-density packaging.

As the above-mentioned trimming means, diamond cutter, sandblasting, ultrasonic cutter, etc. are well known, but these trimming means generate polishing powder, workability is not very good, and highly accurate trimming is difficult. Recently, trimming using a laser beam, which does not have these drawbacks, has been attracting attention.

However, in the conventional method, the trimming electrode 2 is made by applying a conductive paste containing fine powder of silver, palladium, or an alloy thereof as a conductive component onto the ceramic substrate 1 by means such as screen printing, and then baking it. Since it is an electrode, a strong power is required when trimming with a laser beam, and this powerful laser beam can damage the dielectric ceramic substrate 1, resulting in a loss of reliability. It was hot.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a capacitor that can improve reliability by trimming electrodes with high precision and ease of work without damaging dielectric ceramics. do.

In order to achieve the above object, a method for manufacturing a capacitor according to the present invention includes a method for manufacturing a capacitor in which the capacitance is varied by reducing the effective electrode area of a trimming electrode provided on at least one surface of a ceramic substrate. is characterized in that it is formed by using a conductor paste in which a metal powder other than silver is dispersed in an organic vehicle, and by hardening the organic vehicle contained in the conductor paste to adhere it to the ceramic substrate.

That is, when forming the trimming electrode 2,
Conventionally, a baked electrode was created by applying a conductive paste and then baking it, but in the present invention, a conductive paste in which metal powder is dispersed in an organic vehicle is applied onto the dielectric ceramic substrate 1, It is cured by heating and is applied onto the dielectric ceramic substrate 1 using its curing power. No baking process is performed. Therefore, the organic vehicle remains in the trimming electrode 2 without being burnt out. The trimming electrode 2 having such a structure can be trimmed with a laser beam of much lower power than a conventional baked electrode. Therefore, damage to the trimming electrode 2 can be prevented and reliability can be improved. Moreover, the trimming operation can be performed very easily not only when trimming using a laser beam but also when using a trimming means such as a diamond cutter, sandblasting, or an ultrasonic cutter.

As the organic vehicle, a thermosetting resin that can be cured by heating is used. Further, as the metal powder to be dispersed in the organic vehicle, it is desirable to use a metal powder other than silver, such as copper powder. This is because the use of such a metal powder can prevent the occurrence of silver migration that cannot be avoided when silver powder is used, and can improve reliability. For the same purpose, palladium, nickel, tin, lead, gold, platinum, or alloy powders thereof can be used in addition to copper powder.

Note that the pattern, structure, etc. of the trimming electrode 2 and the electrode 3 paired with the trimming electrode 2 are not limited to those shown in this embodiment, and may be arbitrary.

As described above, the present invention provides a method for manufacturing a capacitor whose capacitance is varied by reducing the effective electrode area of a trimming electrode provided on at least one surface of a ceramic substrate, in which the trimming electrode is made of metal in an organic vehicle. The method is characterized in that it is formed by using a conductor paste in which powder is dispersed and adhering it to the ceramic substrate by curing the organic vehicle contained in the conductor paste, so that trimming is not performed with a low-power laser beam. It is possible to manufacture trimming that can trim the electrode with high precision without damaging the dielectric ceramic, with good workability, and with improved reliability.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of trimming, and FIG. 2 is an electric circuit diagram of a crystal oscillation circuit incorporating trimming. 1...Porcelain substrate, 2...Trimming electrode, 3...
…electrode.

Claims (1)

[Claims] 1. A method for manufacturing a capacitor whose capacitance is varied by reducing the effective electrode area of a trimming electrode provided on at least one surface of a ceramic substrate, wherein the trimming electrode is formed by dispersing metal powder in an organic vehicle. A method for manufacturing a capacitor, characterized in that the conductor paste is applied to the ceramic substrate by curing the organic vehicle contained in the conductor paste. 2. The capacitor manufacturing method according to claim 1, wherein the metal powder is a metal powder other than silver.