JP3173230B2 - Manufacturing method of filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is a cordless telephone, the production of filters used in mobile communication devices such as cellular phones
It is about the method .

[0002]

2. Description of the Related Art FIGS. 10 and 11 show a conventional (for example, JP-A-3-71710) filter of this type. In FIG. 10, reference numerals 70 to 76 denote dielectric green sheets, and green sheets 71 and 72 are provided with capacitor electrodes 77, 78, 79, and 80, respectively. The green sheet 74 is provided with electrodes 81 and 82 for coils, and the green sheet 76 is provided with electrodes 83 and 84 for shielding. The green sheets 70 to 76 shown in FIG.
It is fired at a temperature at which (for example, silver and copper) does not disappear, and integrated as shown in FIG. In FIG. 11, 85 and 86 are input / output terminals. That is,
In the conventional device, a capacitor is formed by opposing the electrodes 77 to 80, a coil is formed by the electrodes 81 and 82, and a filter is formed by the capacitor and the coil.

[0003]

The problem with the above prior art is that the filter characteristic cannot be improved as a result of the fact that the no-load Q of the resonator comprising the capacitor and the coil cannot be increased. That is, in FIG. 10, since the green sheets 70 to 76 can be fired only at a temperature at which the electrodes 77 to 84 do not disappear after lamination, the dielectric loss is increased, and as a result, a constant (unloaded Q) indicating a small loss of the resonator is obtained. ) Is low. And
A filter composed of a resonator having a low no-load Q has a large insertion loss in the pass band and has a slow characteristic in the attenuation region, so that it cannot be used in a place where the characteristic is severe.

Accordingly, an object of the present invention is to prevent filter characteristics from deteriorating by increasing the no-load Q of the resonator.

[0005]

In order to achieve the above object, the present invention provides an arrangement in which a back side of a pre-fired substrate is provided with an arc.
Forming a pattern by printing and baking, and the substrate
The first and second switches are provided on the surface side of the
Printing and firing the trip line to form
A pair of the first and second strip lines is formed on the surface side of the body layer.
Printing and firing of the capacitor pattern
And laminating the dielectric layer on the substrate to form a laminate.
Forming the ground pattern on the side surface of the laminate.
Forming a conductive film that is connected to the substrate, and covering the laminate.
Mounting a cap having a conductive surface as described above,
A conductive surface provided on a cap and a side surface of the laminate are provided.
Connecting the conductive film to the conductive film.
The fired substrate is the ground pattern, the first and second
Strip line, first and second capacitor patterns,
And fired at a higher temperature than the dielectric layer
It is assumed that .

[0006]

According to the above construction, since the space is provided on the dielectric layer and the cap is covered, the electric fields from the first and second strip lines are concentrated toward the substrate. However, since this substrate can be used as a single substrate which has been previously fired at a high temperature, the dielectric loss can be reduced, and as a result, the absence of the resonator formed by the first and second strip lines is eliminated. The load Q can be made extremely high, and deterioration of the filter characteristics can be prevented.

[0007]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 are perspective views of a filter according to a first embodiment of the present invention as viewed from the front side and the back side. The front surface side is covered with a metal cap 1, and the back surface and both side surfaces are covered with a ground pattern 2. The input / output terminals 3 are provided on portions where the ground pattern is not provided on the back and side surfaces. The third strip line 7 is provided at one end of the first and second strip lines 5 and 6 on the surface of the substrate 4 so as to be substantially parallel to the outer peripheral surface of the substrate 4. 7, the first and second strip lines 5 and 6 are in a state of being erected. Now, the internal configuration will be described with reference to the exploded perspective view of FIG. In FIG. 3, reference numeral 4 denotes a titanium oxide-based porcelain 1300, for example.
This is a substrate having a high dielectric constant of 100 formed by firing at a high temperature of １1400 degrees. The ground pattern 2 and the input / output terminals 3 are provided on the back and both sides of the substrate 4, and the first and second strip lines 5, 6 and the third strip line 7 are provided on the surface. I have. These first and second strip lines 5, 6 are:
One end is connected to the ground pattern 2 via the third strip line 7, and the other end is opened to form a resonator having approximately a quarter wavelength. Then, these resonators are arranged in parallel and electromagnetically coupled to each other to form a comb-ray type filter. A first dielectric layer 8 having a dielectric constant of 10 is provided on the surface of the substrate 4, and first and second capacitor patterns 9 and 10 are provided on the surface. The first and second capacitor patterns 9 and 10 are:
A capacitor is formed facing the first and second strip lines 5 and 6 via the first dielectric layer 8, and the outer peripheral end is connected to the input / output terminal 3. A second dielectric layer 11 is provided on the surface of the first dielectric layer 8, and the first and second dielectric layers 11 are provided.
Of the capacitor patterns 9 and 10 are protected. The filter is completed by mounting the metal cap 1 on the surface side of the laminate having the above-described configuration. The metal cap 1 is
0.2mm thick, about 5μm silver plated on the front and back
The above oxygen-free copper plate is processed into a box shape with an open lower surface, and a step is provided on the side surface thereof. The upper part of the step is in contact with the surface of the second dielectric layer 11 to secure an appropriate height, and the lower part is bulged outward and covers the side surface of the substrate 4. The lower portion is soldered to the ground pattern 2 on the side surface of the substrate 4 to fix the metal cap 1 and shield the outside. Further, a notch 1a is provided on a side surface of the metal cap 1 so as not to come into contact with the capacitor patterns 9 and 10 when the metal cap 1 is mounted. In the above configuration, since the substrate 4 is fired at a high temperature of 1300 to 1400 ° C. as described above, the sintered state is dense and the dielectric loss is extremely small. It is extremely expensive.

Next, a method of manufacturing the filter will be described with reference to FIG. First, a plurality of ground patterns 2 and a plurality of input / output terminals 3 are printed on a back surface (not shown) using a large-sized substrate 4 fired at a high temperature of 1300 to 1400 degrees by using a conductive paste mainly containing silver powder. ~ 90
Bake at a temperature of 0 degrees. Subsequently, a plurality of first to third striplines 5, 6, and 7 are printed on the surface of the substrate 4 using the conductive paste, and baked at a temperature of 850 to 900 degrees. Next, a plurality of first dielectric layers 8 are printed on the surface using a dielectric paste in which barium titanate-based dielectric powder and lead silicate-based glass are mixed, and 850 to 900
Firing at a temperature of degrees. A plurality of first and second capacitor patterns 9 and 10 are printed and fired on the surface of the first dielectric layer 8 in the same manner as the strip lines 5 to 7. Further, a plurality of second dielectric layers 11 are printed and fired on the surface in the same manner as the first dielectric layer 8. The first dielectric layer 8 and the second dielectric layer 11 are printed at predetermined intervals, respectively, and after lamination, the end of the third strip line 7 and the end of the capacitor patterns 9 and 10 are stacked. Part 1
It is designed to be exposed to about 00 μm. The laminate thus formed is cut along the broken line in the figure and divided into individual pieces. Then, the ground pattern 2 and the input / output terminals 3 are printed on the side surfaces cut as shown in FIG. 3 using the above-mentioned conductor paste, and fired as described above. At this time, the third
Strip line 7 and capacitor patterns 9.1
The exposed portions 0 are connected to the ground pattern 2 and the input / output terminal 3, respectively. Thereafter, the metal cap 1 is mounted on the surface side of the intermediate body, and the metal cap 1 and the ground pattern 2 are soldered on the side surface to obtain the filters shown in FIGS. According to the above manufacturing method, a resonator having a high no-load Q can be obtained using the substrate 4 having a small dielectric loss fired at a high temperature of 1300 to 1400 ° C. The ground pattern, input / output terminals, strip lines 5 to 7, and capacitor patterns 9 and 10 are not burned out.

The first and second strip lines 5 and 7 are connected to the ground pattern 2 via the third strip line 7 as shown in FIG.
With this structure, the lengths of the first and second strip lines 5 and 6 do not change even if a slight displacement occurs at the time of cutting, so that there is little change in resonance frequency, coupling degree, etc., and the characteristics are stable. It becomes possible to obtain a filter.

Next, the operation of this filter will be described. FIG. 5 is an equivalent circuit diagram of this filter. Each of the first and second strip lines 5 and 6 is a resonator having substantially a quarter wavelength, and can be replaced with a parallel resonance circuit of L and C. M represents the electromagnetic field coupling between the two resonators, and the strength of the coupling determines the frequency bandwidth of the signal passing through the filter. Ci is a capacitor formed by the capacitor patterns 9 and 10,
It has the function of matching the input impedance of the filter to the external circuit and cutting the DC component of the signal from the external circuit. Next, the pass characteristics of this filter will be described. FIG. 6A is a cross-sectional view showing the AA cross section of the filter of FIG. 3, and FIG. 6B changes the height (hereinafter, H) from the surface of the substrate 4 to the top surface of the metal cap 1. FIG. 9 is a characteristic diagram illustrating a change in filter pass characteristics in the case. FIG.
(B) shows that the filter characteristic becomes narrower as H becomes smaller. This cause will be described with reference to FIG. FIG. 7 shows an even mode wavelength reduction ratio (hereinafter, Ve) and an odd mode wavelength reduction ratio (hereinafter, Ve) of the resonator due to a change in H.
FIG. 4C is an explanatory diagram showing a change in the filter ratio band. FIG. 7 shows that when H is 1.2 mm, Ve and Vo are equal, and above that, Ve <Vo and the fractional band is large, and below that Ve> Vo and the fractional band becomes small. This is because the internal electric field distribution differs depending on H, and the relationship between Ve and Vo changes.
Changes. When the coupling M is large, the fractional band becomes large, and when the coupling M is small, the fractional band becomes small.

In general, a high-frequency filter for mobile communication is required to have an extremely narrow band characteristic of 4% or less in a fractional band. In the above configuration, such a characteristic is obtained unless Ve ≧ Vo. Can not. For this purpose, the height H of the metal cap 8 must be equal to or less than the height at which Ve = Vo. In the present embodiment, the height H
Was set to 1.0 mm, and a narrow-band filter characteristic of 3.7%, which is suitable for mobile communication, was obtained. Also, no load Q
When a narrow-band filter is formed by a resonator having a low resonance frequency, the insertion loss in the pass band becomes large. However, in the case of this embodiment, since the no-load Q of the resonator is as high as 200 or more, the insertion loss is 1 dB or less. Filter.

(Embodiment 2) Next, a second embodiment of the present invention will be described. FIG. 8 is an exploded perspective view of a filter according to the second embodiment of the present invention, and FIG. 9 is a characteristic diagram showing pass characteristics of the filter. 8, a metal cap 1, a ground pattern 2, an input / output terminal 3, a substrate 4, a third strip line 7, a first dielectric layer 8, first and second capacitor patterns 9, 10 and a second Dielectric layer 11
Is similar to the configuration of FIG. The difference from the configuration of FIG. 3 is that the first and second strip lines 12 and 13 each have a high-impedance portion having a narrow width at one end and a low-impedance portion having a wide width at the other end. . Then, one end of the high impedance portion is connected to the ground pattern 2 via the third strip line 7.
And the other end of the low impedance section is opened to form a resonator. With this configuration, the inductance increases in the relatively high impedance part and the capacitance increases in the low impedance part, so that the length can be shortened as compared with a resonator having a uniform width. is there. Further, as shown in FIG. 9, the pass characteristic of the filter having this configuration is such that an attenuation pole can be generated on the lower side of the pass band due to the coupling state between the resonators. It's a good choice if you have to take a big one.

In the first and second embodiments, the frequency adjustment is performed by trimming the ground pattern 2 provided on the side surface of the substrate 4. The ground pattern 2 on these side surfaces is the metal cap 1 and the ground pattern 2 on the back of the substrate 4.
This is formed for the purpose of connecting the frequency band and the frequency, and the frequency is adjusted by positively using the frequency band. That is, if the ground pattern 2 on one end side of the first and second strip lines 5, 6, 12, 13 (that is, on the third strip line 7 side) is trimmed, the inductance of this portion increases, and the resonance frequency is increased. Can be lowered. Conversely, if the ground pattern 2 at the other end is trimmed, the open end capacity between the other end and the ground pattern 2 is reduced, and the resonance frequency can be increased. Further, when the other end side is trimmed, the ground pattern 2 in this portion functions as an inductance, so that an LC series resonance circuit is formed between the ground pattern 2 and the open end capacitance. As a result, a new attenuation pole is generated at the resonance frequency of the LC series resonance circuit in the filter characteristic, and the attenuation characteristic becomes excellent.

[0014]

[0015]

As described above, according to the present invention, since the space is provided on the dielectric layer and the cap is covered, the electric fields from the first and second strip lines are concentrated toward the substrate. However, since the substrate can be used as a single substrate which has been baked at a high temperature in advance, the dielectric loss can be reduced, and as a result, the substrate can be formed by the first and second strip lines. Thus, the no-load Q of the resonator can be made extremely high, and deterioration of the filter characteristics can be prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view of a filter according to a first embodiment of the present invention as viewed from the surface thereof.

FIG. 2 is a perspective view of the filter according to the first embodiment of the present invention as viewed from the back surface of the filter.

FIG. 3 is an exploded perspective view of a filter according to the first embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a filter manufacturing method according to the first embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram of a filter according to the first embodiment of the present invention.

6A is a cross-sectional view illustrating a cross section taken along line AA of FIG. 3; FIG. 6B is a characteristic view illustrating pass characteristics of a filter according to the first embodiment of the present invention;

FIG. 7 is a relationship diagram showing the relationship between the height of the metal case of the filter, the even-odd mode wavelength reduction ratio, and the bandwidth ratio in the first embodiment of the present invention.

FIG. 8 is an exploded perspective view of a filter according to a second embodiment of the present invention.

FIG. 9 is a characteristic diagram showing a pass characteristic of a filter according to the second embodiment of the present invention.

FIG. 10 is an exploded perspective view showing a conventional example.

FIG. 11 is a perspective view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 metal cap 2 ground pattern 3 input / output terminal 4 substrate 5 first strip line 6 second strip line 7 third strip line 8 first dielectric layer 9 first capacitor pattern 10 second capacitor pattern 11 Second dielectric layer

Continuing from the front page (72) Inventor Takeshi Himori 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. References JP-A-5-152804 (JP, A) JP-A-3-145111 (JP, A) JP-A-4-72804 (JP, A) JP-A-4-284003 (JP, A) 56-128705 (JP, U) JP-A-1-67756 (JP, U) JP-A-57-53701 (JP, U) US Pat. No. 4,281,302 (US, A) (58) Fields investigated (Int. Cl. ⁷⁾ H01P 11/00 H01P 1/203 H01P 1/205

Claims (6)

(57) [Claims] 1. An adhesive is provided on the back side of a pre-fired substrate.
Forming a base pattern by printing and firing;
First and second electromagnetically coupled first and second
Printing and baking the strip line to form
The first and second strip lines on the surface side of the electric conductor layer;
Forming by printing and firing opposing capacitor patterns
And laminating the dielectric layer on the substrate to form a laminate
Forming a ground pattern on the side surface of the laminate.
Forming a conductive film connected to the laminate, and covering the laminate.
Mounting a cap having a conductive surface such that
A conductive surface provided on the cap and a side surface of the laminate.
Connecting the conductive film to the conductive film,
The pre-fired substrate is the ground pattern, the first and second
Strip line, first and second capacitor putters
And firing at a higher temperature than the dielectric layer.
A method for manufacturing a filter characterized by the following. 2. The substrate fired beforehand is 1300-1000.
Fired at 1400 degrees, ground patterns, first and second strip lines, first and second capacitor patterns,
The method according to claim 1, wherein the dielectric layer is fired at 850 to 900 degrees . 3. One end of each of the first and second strip lines provided on the substrate surface is connected to a conductive film on the outer peripheral surface of the substrate, and the other end of each of the first and second strip lines is connected. And a conductive film connected to the ground pattern on the back surface of the substrate is also provided on the outer peripheral surface portion of the substrate facing the substrate, and the conductive film is not connected to the other ends of the first and second strip lines. 3. The method for producing a filter according to 1.). 4. The distance from the top surface of the cap to the surface of the substrate is a height at which the even mode wavelength reduction rate and the odd mode wavelength reduction rate of the first and second strip lines are equal to each other, or less than the height. A method for producing the filter according to claim 3.
Law. 5. The method according to claim 3, wherein one end of each of the first and second strip lines has a small width and the other end has a large width . 6. A pattern substantially parallel to the outer peripheral surface of the substrate is formed on one end side of the first and second strip lines on the surface of the substrate, and the first and second strip lines are planted from this pattern. The method for manufacturing a filter according to any one of claims 1 to 5, wherein the filter has a shaped shape .