JP2002026604A - Electric characteristic adjustment method for ceramic dielectric component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric characteristic adjustment method for a ceramic dielectric component by which the electric characteristic such as a center frequency of a ceramic dielectric component of a dielectric filter can efficiently be adjusted. SOLUTION: The dielectric filter 11 is structured such that a surface electrode 13 of an Ag conductor is formed on both sides of a low temperature sintered ceramic dielectric body 12 made of a Ba-Nd-Ti-Bi-Pb-glass additive group or the like by the thick film method. In the case of adjusting the center frequency of the dielectric filters 11, the dielectric filters 11 after sintering are sorted out by offsets of the center frequency and heat treatment is applied to the dielectric filters 11 with the same offset. In this case, the heat treatment temperature is adjusted within a range from 700 deg.C to the sintering temperature of the dielectric filters 11 depending on the offset of the center frequency to adjust the center frequency of the dielectric filters 11 to have the desired center frequency. Thus, the center frequencies of many dielectric filters 11 can efficiently be adjusted by one heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the electrical characteristics of a ceramic dielectric component, which is an improved method for adjusting the electrical characteristics of a ceramic dielectric component.

[0002]

2. Description of the Related Art In recent years, dielectric filters have been widely used as band-pass filters in portable information communication equipment and the like. This dielectric filter has a structure in which a surface electrode is formed at a predetermined position on a ceramic dielectric formed into a rectangular parallelepiped shape or a cylindrical shape. Since the center frequency of this dielectric filter varies due to manufacturing variations and the like, a step of adjusting the center frequency after manufacturing the dielectric filter is required.

[0003] In a conventional method of adjusting the center frequency of a dielectric filter, the center frequency of the dielectric filter is adjusted by adjusting the shape of the surface electrode or the shape of the ceramic dielectric after the dielectric filter is manufactured. Was.

[0004]

In the conventional method of adjusting the center frequency of a dielectric filter, since the shape of the surface electrode or the shape of the ceramic dielectric is adjusted after the dielectric filter is manufactured, the adjustment operation is troublesome. In addition, it is necessary to adjust the dielectric filters one by one, so that the efficiency of the adjustment operation is very poor, and the production cost is correspondingly high.

The present invention has been made in view of such circumstances, and accordingly, it is an object of the present invention to efficiently adjust the electric characteristics such as the center frequency of a ceramic dielectric component, and to improve the productivity and production. It is an object of the present invention to provide a method for adjusting the electrical characteristics of a ceramic dielectric component, which can reduce the cost.

[0006]

In order to achieve the above object, a method for adjusting the electrical characteristics of a ceramic dielectric component according to the present invention comprises a method of adjusting the electrical characteristics of a ceramic dielectric component formed of a low-temperature fired ceramic dielectric after firing. When the ceramic dielectric component is heat-treated, the electrical characteristics of the ceramic dielectric component are adjusted by adjusting the heat treatment temperature. In other words, the ceramic dielectric components after firing are selected according to the deviation amount of the electric characteristics such as the center frequency, and the ceramic dielectric parts having the same deviation amount are collectively heat-treated.
At this time, the electric characteristics of the ceramic dielectric component are adjusted to desired characteristics by adjusting the heat treatment temperature according to the deviation amount of the electric characteristics. This makes it possible to efficiently adjust the electrical characteristics of many ceramic dielectric components by one heat treatment.

In this case, the center frequency of the ceramic dielectric component may be adjusted by adjusting the heat treatment temperature in a range from 700 ° C. to the firing temperature of the ceramic dielectric component. . That is, as is clear from the experimental results of the inventor described later, when the heat treatment temperature is lower than 700 ° C., the effect of the heat treatment is small, and the change width of the center frequency is small. On the other hand, if the heat treatment temperature is higher than the firing temperature, the physical and electrical characteristics of the ceramic dielectric component deteriorate due to high heat, and the reliability of the ceramic dielectric component decreases. Therefore, if the heat treatment temperature is adjusted in the range from 700 ° C. to the firing temperature of the ceramic dielectric component, the center frequency can be adjusted efficiently while maintaining the reliability of the ceramic dielectric component.

Further, when adjusting the electric characteristics of the ceramic dielectric component having the surface electrode,
The electrical characteristics of the ceramic dielectric component may be adjusted by forming a plating film on the surface of the surface electrode and adjusting the thickness of the plating film. In this case, the fired ceramic dielectric components are selected in accordance with the deviation of the electrical characteristics such as the center frequency, and the surface electrodes of the ceramic dielectric components having the same deviation are collectively plated. At this time, the electric characteristics of the ceramic dielectric component are adjusted to desired characteristics by adjusting the thickness of the plating film according to the deviation amount of the electric characteristics. This makes it possible to efficiently adjust the electrical characteristics of many ceramic dielectric components by a single plating process.

In this case, it is preferable to adjust the center frequency of the ceramic dielectric component by adjusting the thickness of the plating film within a range of 20 μm or less. In other words, as is clear from the experimental results of the inventor described later, as the thickness of the plating film increases, the width of change in the center frequency increases, but when the thickness of the plating film is greater than 20 μm, the minimum loss ( The deterioration of the insertion loss becomes large, and the effect cannot be ignored. Therefore, in order to reduce the deterioration of the minimum loss, the thickness of the plating film is preferably set to 20 μm or less.

[0010]

[Embodiment (1)] In the embodiment (1) of the present invention, the center frequency of the dielectric filter 11 is adjusted by heat treatment. As shown in FIG. 1, the dielectric filter 11 has a structure in which a surface electrode 13 is formed on a surface of a low-temperature fired ceramic dielectric 12 by a thick film method. As the low-temperature fired ceramic dielectric 12, for example, Ba-
Nd-Ti-Bi-Pb- glass additive system, silicate _{(BaO-Al 2 O 3 -SiO} 2 -B 2 O 3 , etc.), Pb
A low-temperature fired ceramic dielectric that can be fired at 1000 ° C. or less, such as a perovskite-based ceramic dielectric, may be used. The surface electrode 13 is made of a thick-film conductor that can be co-fired with the low-temperature fired ceramic dielectric 12, such as Ag, Ag / Pd, Ag / Pt, or the like.
Au, Cu, or the like may be used. The surface electrode 13 is fired simultaneously with the low temperature fired ceramic dielectric 12, or
After firing the low temperature fired ceramic dielectric 12, the surface electrode 13
May be added later by a thick film method.

When the center frequency of the dielectric filter 11 is adjusted, the fired dielectric filter 11 is selected according to the shift amount of the center frequency, and the dielectric filters 11 having the same shift amount are heat-treated together. At this time, the center frequency of the dielectric filter 11 is adjusted to a desired center frequency by adjusting the heat treatment temperature in a range from 700 ° C. to the firing temperature of the dielectric filter 11 according to the shift amount of the center frequency. As a result, the center frequency of many dielectric filters 11 can be efficiently adjusted by a single heat treatment, thereby improving productivity and reducing production cost.

The present inventor conducted a test for evaluating the relationship between the heat treatment temperature of the dielectric filter 11 and the center frequency after the heat treatment. The test results are shown in Table 1 below.

[0013]

[Table 1]

The low temperature fired ceramic dielectric 12 of the dielectric filter 11 used in this test is made of Ba-Nd-Ti-B.
It is an i-Pb-glass additive-based low-temperature fired ceramic dielectric, and the surface electrode 13 is formed of an Ag conductor.
The firing temperature of the dielectric filter 11 is 930 ° C.
The heat treatment was performed for one hour in the air.

The center frequency of the dielectric filter 11 before the heat treatment was 870 MHz, and it was confirmed that the center frequency after the heat treatment changed depending on the heat treatment temperature. When the heat treatment temperature is 730 ° C., 780 ° C., 830 ° C., the center frequency after the heat treatment is higher than the center frequency before the heat treatment,
When the heat treatment temperature was 870 ° C. or 900 ° C., the center frequency after the heat treatment was lower than the center frequency before the heat treatment.
When the heat treatment temperature is in the range of 830 to 870 ° C., there is a temperature T at which the center frequency hardly changes before and after the heat treatment, and when the heat treatment temperature is higher than this temperature T, the center frequency after the heat treatment becomes the center frequency before the heat treatment. Lower than the frequency,
Conversely, when the heat treatment temperature is lower than the temperature T, the center frequency after the heat treatment becomes higher than the center frequency before the heat treatment.

In this case, if the heat treatment temperature is lower than 700 ° C., the effect of the heat treatment is small, and the variation of the center frequency is small. If the heat treatment temperature is higher than the firing temperature (930 ° C.), the physical properties and electrical properties of the dielectric filter 11 deteriorate due to high heat, and the reliability of the dielectric filter 11 decreases.
Therefore, the heat treatment temperature is increased from 700 ° C. to the firing temperature (930
C.), the center frequency can be adjusted efficiently while maintaining the reliability of the dielectric filter 11. In particular, when the heat treatment temperature is in the range from about 850 ° C. to the sintering temperature (930 ° C.), the center frequency changes linearly toward the low frequency range according to the heat treatment temperature. The adjustment of the center frequency is easy.

The adjustment of the center frequency by the heat treatment of the embodiment (1) can be applied to dielectric filters having various structures. Further, in addition to the dielectric filters, other ceramic dielectric parts such as resonators can be used. Also applicable to Further, electrical characteristics other than the center frequency of the ceramic dielectric component may be adjusted by heat treatment. After the heat treatment, the surface of the surface electrode 13 may be plated.

[Embodiment (2)] In the embodiment (2) of the present invention, as shown in FIG. 2, the thickness of the plating film 14 formed on the surface of the surface electrode 13 of the dielectric filter 11 is adjusted. Then, the center frequency of the dielectric filter 11 is adjusted. The low-temperature fired ceramic dielectric 12 and the surface electrode 13 of the dielectric filter 11 are the same as those in the embodiment (1).

When adjusting the center frequency of the dielectric filter 11, the dielectric filter 11 after firing (before plating) is selected according to the shift amount of the center frequency, and the dielectric filter 11 having the same shift amount is selected. The surface electrode 13 is collectively plated to form a plating film 14 on the surface of the surface electrode 13. Before and after this plating process, the filter characteristics of the dielectric filter 11 change as shown in FIG. 3, and the center frequency after the plating process changes to a lower frequency range than the center frequency before the plating process. In this plating step, the center frequency of the dielectric filter 11 is adjusted to a desired center frequency by adjusting the thickness of the plating film 14 within a range of 20 μm or less according to the shift amount of the center frequency. This makes it possible to efficiently adjust the center frequency of many dielectric filters 11 by one plating process.

In this case, the type of the plating film 14 may be selected according to the specifications of the surface electrode 13, such as Sn plating using Ni plating as a base, or Au plating using Ni plating as a base.

The present inventor has performed tests 1 to 3 for evaluating the relationship between the thickness of the plating film 14 and the center frequency of the dielectric filter 11 before and after the plating process. The test results will be described. In these tests 1 to 3, the surface of the surface electrode 13
Sn plating (Ni / Sn plating) using Ni plating as a base was performed by electrolytic plating.

<< Test 1 >> The plating conditions of Test 1 and the changes in the filter characteristic values before and after the plating are shown in Table 2 below.

[0023]

[Table 2]

In Test 1, the surface of the surface electrode 13
By forming a 6.1 μm Ni / Sn plating film (a 2.3 μm Ni plating film and a 3.8 μm Sn plating film), the center frequency could be adjusted to 1.6 MHz in the lower frequency range, but the minimum The deterioration of the loss (insertion loss) is 0.03 dB
Stay and can be ignored.

<< Test 2 >> Table 3 shows the plating conditions of Test 2 and changes in filter characteristic values before and after plating.

[0026]

[Table 3]

In Test 2, the surface of the surface electrode 13
12.5 μm Ni / Sn plated film (4.5 μm Ni
By forming a plating film and an Sn plating film of 8.0 μm), the center frequency could be adjusted to 3.4 MHz in the lower frequency range, but the deterioration of the minimum loss was only 0.05 dB,
I can ignore it.

<< Test 3 >> The plating conditions of Test 3 and changes in filter characteristic values before and after plating are shown in Table 4 below.

[0029]

[Table 4]

In Test 3, the surface of the surface electrode 13
14.4 μm Ni / Sn plated film (5.2 μm Ni
By forming a plating film and a 9.2 μm Sn plating film), the center frequency could be adjusted to 4.0 MHz in the lower frequency range, but the degradation of the minimum loss was only 0.01 dB,
I can ignore it.

From the results of the above tests 1 to 3, Ni / Sn
It was found that the relationship between the thickness of the plating film and the change width of the center frequency became linear as shown in FIG. Since the thickness of the Ni / Sn plating film can be adjusted by the plating time,
The relationship between the plating time and the change width of the center frequency is measured in advance by an experiment or the like. Then, the center frequency can be adjusted easily and accurately. Since the thickness of the plating film varies depending on the current during the plating process, the thickness of the plating film is adjusted by the current, or, of course, the thickness of the plating film is adjusted by both the current and the plating time. You may do it.

As is clear from FIG. 4, as the thickness of the plating film increases, the width of change in the center frequency increases linearly. However, when the thickness of the plating film exceeds 20 μm,
The deterioration of the minimum loss becomes large, and the effect cannot be ignored. Therefore, in order to reduce the deterioration of the minimum loss, the thickness of the plating film is preferably set to 20 μm or less. If the thickness of the plating film is adjusted within the range of 20 μm or less, the center frequency can be suppressed while suppressing the deterioration of the minimum loss. Can be adjusted efficiently.

The adjustment of the center frequency by the plating process of the embodiment (2) can be applied to dielectric filters having various structures. Further, in addition to the dielectric filters, other ceramic dielectrics such as resonators can be used. It can be applied to parts. The ceramic dielectric is not limited to a low-temperature fired ceramic dielectric fired at 1000 ° C. or lower, and a ceramic dielectric fired at 1000 ° C. or higher may be used. Further, electric characteristics other than the center frequency of the ceramic dielectric component may be adjusted by plating.

[0034]

As is apparent from the above description, according to the first aspect of the present invention, after the ceramic dielectric component is fired, the heat treatment temperature is adjusted when the ceramic dielectric component is heat-treated. Since the electric characteristics of the ceramic dielectric parts are adjusted, the electric characteristics of a large number of ceramic dielectric parts can be efficiently adjusted by one heat treatment, thereby improving the productivity and reducing the production cost. can do.

Further, in claim 2, the heat treatment temperature is set to 700.
The center frequency of the ceramic dielectric component was adjusted by adjusting the temperature in the range from ℃ to the firing temperature, so that the center frequency could be adjusted efficiently while maintaining the reliability of the ceramic dielectric component. it can.

In the third aspect, the electric characteristics of the ceramic dielectric component are adjusted by adjusting the thickness of the plating film formed on the surface electrode of the ceramic dielectric component. The electrical characteristics of the dielectric component can be efficiently adjusted by a single plating process, so that productivity can be improved and production cost can be reduced.

Further, in claim 4, the thickness of the plating film is 2
Since the center frequency of the ceramic dielectric component is adjusted by adjusting the range of 0 μm or less, the center frequency can be adjusted efficiently while suppressing the deterioration of the minimum loss.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a dielectric filter used in an embodiment (1) of the present invention.

FIG. 2 is a longitudinal sectional view of a dielectric filter used in an embodiment (2) of the present invention.

FIG. 3 is a diagram showing a change in filter characteristics of a dielectric filter before and after a plating process.

FIG. 4 is a diagram showing experimental data obtained by measuring the relationship between the thickness of a plating film and the width of change in the center frequency.

[Explanation of symbols]

11 ... dielectric filter (ceramic dielectric component), 12
... Low temperature firing ceramic dielectric, 13 ... Surface electrode, 14 ...
Plating film.

Claims (4)

[Claims] 1. A method for adjusting electrical characteristics of a ceramic dielectric component formed of a low-temperature fired ceramic dielectric, comprising: adjusting a heat treatment temperature when heat-treating the ceramic dielectric component after firing the ceramic dielectric component. Thereby adjusting the electrical characteristics of the ceramic dielectric component. 2. The center frequency of the ceramic dielectric component is adjusted by adjusting the heat treatment temperature in a range from 700 ° C. to a firing temperature of the ceramic dielectric component. Method for adjusting electrical characteristics of ceramic dielectric component. 3. A method for adjusting electric characteristics of a ceramic dielectric component having a surface electrode, comprising: forming a plating film on a surface of the surface electrode; and adjusting a film thickness of the plating film. A method for adjusting the electrical characteristics of a ceramic dielectric component, comprising adjusting the electrical characteristics of a body component. 4. The ceramic dielectric component according to claim 3, wherein a center frequency of the ceramic dielectric component is adjusted by adjusting a thickness of the plating film within a range of 20 μm or less. Characteristics adjustment method.