JPH0983211A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the profile of the dielectric filter and to reduce the cost in the dielectric filter configured by mounting a dielectric resonator on an insulation board with an electrode pattern formed thereon. SOLUTION: First and second dielectric resonators 2, 3, 4, 5 whose outer circumferential face is formed with an outer conductor is mounted onto an insulation board 1 only on the front side of which an electrode pattern 16 is formed in a way that the dielectric resonators 2, 3, 4, 5 are mounted so as to be overlapped onto a hot electrode part of the electrode pattern 16. A solder resist 17 consisting of at least two layers is formed to a hot electrode part on the electrode pattern 16 and overlapped onto at least the outer conductor of the dielectric resonator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter, and more particularly to a dielectric filter having a dielectric resonator mounted on an insulating substrate having an electrode pattern formed thereon.

[0002]

2. Description of the Related Art Conventionally, this type of dielectric filter is constructed as shown in FIG. 19, FIG. 21 and FIG. The dielectric filter shown in FIGS. 19 and 21 has a dielectric resonator and a lumped constant circuit element mounted on a multilayer substrate, and the dielectric resonator and the lumped constant circuit element form a predetermined filter circuit. It was done like this. In the dielectric filter shown in FIG. 23, a dielectric resonator is mounted on a multilayer substrate, and a terminal electrode formed on the dielectric resonator is connected to a terminal electrode formed on the multilayer substrate. The position of the terminal electrode of the dielectric resonator is substantially changed.

That is, in FIG. 19, a dielectric resonator 101 is a multilayer substrate 103 having an internal electrode 102 formed thereon.
Mounted on. This dielectric resonator 101 is shown in FIG.
As shown in 0, the inner conductor 106 is formed on the inner peripheral surface of the through hole 105 formed in the rectangular parallelepiped dielectric block 104, and the terminal is provided on the bottom surface side of the dielectric block 104 so as to face the inner conductor 106. The electrode 107 is formed, and the outer conductor 109 is formed on the outer peripheral surface of the dielectric block 104.
It is formed so as to surround. In this dielectric resonator 101, its terminal electrode 107 is soldered to the hot electrode 110 on the multilayer substrate 103, and its outer conductor 109
Are soldered to the ground electrode 111 on the multilayer substrate 103.

The hot electrode 110 is the via hole 1
12 is connected to the internal electrode 102 via 12, and the internal electrode 102 is connected via the via hole 113 to another hot electrode 114 on the multilayer substrate 103. The coil 115 is soldered to the hot electrode 114. There is. That is, when the hot electrode 110 and the hot electrode 114 are directly connected on the substrate, the connection portion is the dielectric resonator 101.
On the substrate of the dielectric resonator 101 formed by being surrounded by the outer conductor 109, the terminal electrode 107 is formed by connecting via the inner electrode 102 as described above. It is possible to attach to.

In FIG. 21, the dielectric resonator 12 is also shown.
1 is mounted on the multilayer substrate 123 on which the internal electrodes 122 are formed. As shown in FIG. 22, in this dielectric resonator 121, an inner conductor 126 is formed on the inner peripheral surface of a through hole 125 formed in a rectangular parallelepiped dielectric block 124, and one end surface of the dielectric block 124 is formed. The outer conductor 127 is formed on the entire outer peripheral surface except for. In this dielectric resonator 121, the outer conductor 127 is a multilayer substrate 123.
Soldered to the upper ground electrode 128 and its inner conductor 12
6 is soldered to the hot electrode 129 on the multilayer substrate 123 via the capacitor 130.

The hot electrode 129 is used as the via hole 13.
It is connected to the internal electrode 122 via 1 and the internal electrode 122 faces the ground electrode 132 on the lower surface of the multilayer substrate 123. That is, the internal electrode 122
Serves as a capacitor electrode that forms a capacitor with the ground electrode 132. If this electrode is formed on the substrate, a space is required and the dielectric filter becomes large. Therefore, as described above, The use of 122 makes it possible to downsize the dielectric filter.

Further, in FIG. 23, the dielectric resonator 14
1 is a multilayer substrate 1 on which internal electrodes 142 and 143 are formed.
It is mounted on the 44. This dielectric resonator 141 is
As shown in FIG. 24, a rectangular parallelepiped dielectric block 14
5, a plurality of through holes 146, 147, 148,
Inner conductors 150, 151, 152, 15 on the inner peripheral surface of 149
3 is formed, a pair of terminal electrodes 154 and 155 are formed on the bottom surface side of the dielectric block 145 so as to face the inner conductors 150 and 153 of the outer through holes 146 and 149, and the outer peripheral surface of the dielectric block 145 is formed. The outer conductor 156 is formed so as to surround the pair of terminal electrodes 154 and 155. In the dielectric resonator 141, the pair of terminal electrodes 154 and 155 are soldered to the pair of hot electrodes 158 and 159 on the multilayer substrate 144, and the outer conductor 1
56 is soldered to the ground electrode 160 on the multilayer substrate 144.

The hot electrodes 158 and 159 are connected to the internal electrodes 142 and 143 through the via holes 161 and 162.
The internal electrodes 142 and 143 are respectively connected to the terminal electrodes 165 and 166 formed on the bottom surface side of the multilayer substrate 144 via the via holes 163 and 164. That is, when the hot electrodes 158 and 159 and the terminal electrodes 165 and 166 are directly connected to each other via the side surface of the substrate, the connection portion is the outer conductor 1 of the dielectric resonator 141.
Since it is short-circuited with 56, the hot electrodes 158 and 159 and the terminal electrodes 165 and 166 can be connected by connecting via the internal electrodes 142 and 143 as described above.

With this structure, the pair of terminal electrodes 154 and 155 of the dielectric resonator 141 are substantially changed to the positions of the terminal electrodes 165 and 166 of the multilayer substrate 144, respectively. Thus, the multilayer substrate 14
4 is used to connect the terminal electrodes 154 and 1 of the dielectric resonator 141.
The position of 55 is changed because the filter characteristic of the dielectric filter changes if it is changed directly on the dielectric block 145. Although not shown, the outer conductor 15
Similarly to the terminal electrodes 154 and 155, 6 is also connected to the terminal electrode on the bottom surface side of the multilayer substrate 144 via another internal electrode.

[0010]

However, although the above-mentioned conventional dielectric filter has various advantages due to the use of the multilayer substrate, the multilayer substrate is formed by laminating a plurality of substrates and electrode patterns. Since it is formed as described above, there is a problem that the thickness is inevitably increased, and as a result, the height reduction of the dielectric filter is hindered.

Further, since the manufacturing process of the multi-layer substrate is complicated, the multi-layer substrate is inevitably expensive, which causes a problem of hindering the cost reduction of the dielectric filter.

[0012] Therefore, an object of the present invention is to provide a dielectric filter which can be made low in height without sacrificing the advantages obtained by using a multi-layer substrate, and at the same time can be reduced in cost.

[0013]

In order to achieve such an object, in a dielectric filter according to a first aspect of the present invention, an outer conductor is formed on an outer peripheral surface on an insulating substrate having an electrode pattern formed only on the surface. The mounted dielectric resonator is mounted so as to overlap the hot electrode portion of the electrode pattern, and at least two layers of solder resist are formed on the hot electrode portion of the electrode pattern that overlaps the outer conductor of the dielectric resonator. It is characterized by that.

In the dielectric filter according to claim 1,
Even if the dielectric resonator is mounted on the hot electrode portion of the electrode pattern so that the outer conductor thereof overlaps, at least two layers of solder resist exist in the hot electrode portion, so that the outer conductor of the dielectric resonator is formed. There will be no short circuit between the hot electrode and the hot electrode, and no discharge will occur.

The dielectric filter according to claim 2 is
According to a first aspect of the present invention, a lumped constant circuit element is mounted on an insulating substrate, and a predetermined filter circuit is formed by the dielectric resonator and the lumped constant circuit element.

In the dielectric filter according to claim 2,
Dielectric filters having various filter characteristics are realized by the dielectric resonator and the lumped constant circuit element.

The dielectric filter according to claim 3 is
The solder resist according to claim 1 or 2 is characterized in that colors thereof are different from each other.

In the dielectric filter according to claim 3,
Since the colors of the solder resist are different from each other, it is possible to visually confirm whether or not a predetermined solder resist is formed.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a dielectric filter according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an exploded perspective view of a metal case of a dielectric filter according to the present invention. In this figure, a dielectric filter includes an insulating substrate 1 having a predetermined electrode pattern formed only on its surface, a first dielectric resonator 2 mounted on the insulating substrate 1, and a plurality of second dielectric resonators. 3,
4, 5, a plurality of capacitors 6, 7, 8 which are lumped constant circuit elements mounted on the insulating substrate 1, and a plurality of capacitors for connecting the second dielectric resonators 3, 4, 5 and the capacitors 6, 7, 8 Lead terminals 9, 10, 11 and a plurality of coils 12, 13, 14, which are lumped constant circuit elements mounted on the insulating substrate 1,
The coil 12, 13, 14 on the insulating substrate 1 is covered with a metal case 15 and the like, and constitutes the duplexer shown in the equivalent circuit diagram of FIG. 2 used for mobile communication equipment and the like.

The insulating substrate 1 is a paper-based epoxy resin,
It is made of a wiring board material such as paper base phenolic resin.
As shown in FIG. 3, an electrode pattern 16 is formed on the first surface, which is the mounting surface of the dielectric resonator 2 and the second dielectric resonators 3, 4, and 5 of FIG. A solder resist 17 (hatched portion) is formed on the top. Further, as shown in FIG. 4, an electrode pattern 18 is formed on the opposite surface, that is, the second surface.
A solder resist 19 (hatched portion) is formed on the surface 8.

The electrode pattern 16 on the first surface is, as shown in FIG. 5, a hot electrode 16 which serves as a path for a received signal.
a, 16b, a hot electrode 16c which is a path of a transmission signal,
16d, 16e and earth electrodes 16f, 16g, 16h
Is formed from. In addition, as shown in FIG. 6, the electrode pattern 18 on the second surface includes a first terminal electrode 18a that serves as an antenna terminal, a second terminal electrode 18b that serves as an Rx terminal on the receiver side, and a Tx on the transmitter side. It is composed of a third terminal electrode 18c which serves as a terminal and an earth electrode 18d which serves as a shield electrode. Hot electrode 16 of the electrode pattern 16
a, 16b and 16e are the connection electrodes CE1, CE2 and CE on the side surface of the substrate for the first terminal electrode 18a, the second terminal electrode 18b and the third terminal electrode 18c of the electrode pattern 18, respectively.
3 are connected to each other.

The ground electrode 16f of the electrode pattern 16 is connected to the ground electrode 18d of the electrode pattern 18 via the connection electrodes CE4 to CE13 and the through holes TH1 to TH4 on the side surface of the substrate, and the ground electrode 16g of the electrode pattern 16 is Connection electrodes CE14 to CE1 on the side surface of the substrate
6 and the ground electrode 18d of the electrode pattern 18 via the through hole TH5, and the ground electrode 16h of the electrode pattern 16 is connected to the connection electrodes CE17 to CE19 on the side surface of the substrate.
It is connected to the ground electrode 18d of the electrode pattern 18 via. The hot electrode 16 of the electrode pattern 16
c, 16d, and 16e also have a function as a capacitor electrode that forms a capacitor as a lumped circuit constant element via the insulating substrate 1 together with the ground electrode 18d of the electrode pattern 18 on the opposite surface.

The electrode patterns 16 and 18 are formed, for example, by etching a copper thick film laminated on the insulating substrate 1. The insulating substrate 1 may be made of a ceramic material such as alumina, and in this case, the electrode patterns 16 and 18 may be formed by printing a noble metal paste such as Ag or Ag-Pd and firing the paste.

The solder resist 17 on the electrode pattern 16 is the first layer solder resist 17a having the pattern shown in FIG. 7 and the first layer solder resist 17.
It is formed with the second layer solder resist 17b having the pattern shown in FIG. In this embodiment, the first-layer solder resist 17a and the second-layer solder resist 17b have the same pattern, and each of them has a thickness of 25 to 45 μm. The first layer solder resist 17a is
A solder resist material made of resin is applied onto the electrode pattern 16 by means of screen printing or the like, and is subjected to a baking treatment to be formed. The first layer solder resist 17a has a color such as blue or green.

Further, the second layer solder resist 17b
Is a resin material for display intended to display part numbers such as resistors and capacitors and a serial number on the wiring board is applied onto the solder resist 17a of the first layer by means of screen printing or the like, and is subjected to a baking treatment. Is formed. The second-layer solder resist 17b has a color different from that of the first-layer solder resist 17a and exhibits, for example, white. The first layer solder resist 17a is
It is necessary to use the original solder resist material because it requires high printing accuracy, but the second layer solder resist 17b does not require printing accuracy as much as the first layer solder resist 17a. It is possible to use a resin material for display.

In this way, the second layer solder resist 1
When a display resin material is used as 7b, cost advantage arises because the material is usually inexpensive. In addition, the solder resist 17 is replaced with the two-layer solder resist 1 as described above.
The layers 7a and 17b are formed in order to obtain a sufficient withstand voltage characteristic between the hot conductor and the outer conductor of the dielectric resonator, which will be described later, at the ground potential by increasing the thickness of the solder resist.

The solder resist 19 on the electrode pattern 18 has a pattern shown in FIG. 9, and the same solder resist material as the first layer solder resist 17a on the electrode pattern 16 is formed by means of screen printing or the like. Are formed on the electrode pattern 18 by a baking process. The thickness is the same as the solder resist 17a, 1
It is formed within the same range of 25 to 45 μm as 7b.

The first dielectric resonator 2 is constructed as shown in FIG. That is, four through holes 22, 23, 24, 25 are formed along the longitudinal direction of the rectangular parallelepiped dielectric block 21, and these through holes 2
Inner conductors 26, 27, 28, in 2, 23, 24, 25
29 are formed. Terminal electrodes 30 and 31 are formed at the bottom surface positions of the dielectric block 21 facing the inner conductors 26 and 29 of the through holes 22 and 25 at both ends, and between the terminal electrode 30 and the inner conductor 26 and between the terminal electrode 31 and the inner electrode 31. Capacitance is formed between the conductor 29 and the conductor 29. In addition, the dielectric block 2 excluding the periphery of the terminal electrodes 30 and 31
The outer conductor 32 is formed on the entire outer peripheral surface of the outer conductor 1.
2 is connected to the inner conductors 26, 27, 28, 29 at both openings of the through holes 22, 23, 24, 25. Each inner conductor 26, 27, 28, 29 has an annular gap formed along the inner peripheral surface in the vicinity of one opening,
The through holes 22, 23, 24, 25 are in a discontinuous state.

The terminal electrodes 30 and 31 of the thus-configured first dielectric resonator 2 are soldered to the hot electrodes 16a and 16b exposed from the solder resist 17 shown in FIG. The conductor 32 is the solder resist 1
7 are attached to the insulating substrate 1 by being soldered to the ground electrodes 16f and 16g exposed from 7. As a result, the first dielectric resonator 2 forms a filter (a filter formed between the antenna terminal and the Rx terminal) on the receiving circuit side of the equivalent circuit shown in FIG. In some cases, it may be more appropriate to call the dielectric resonator 2 by itself a dielectric filter, but here, all such dielectric resonators are called a dielectric resonator.

Further, the second dielectric resonators 3, 4, 5
Is configured as shown in FIG. That is, one through hole 36 is formed along the longitudinal direction of the rectangular parallelepiped dielectric block 35, and the inner conductor 37 is formed on the inner peripheral surface of the through hole 36. An outer conductor 38 is formed on the entire outer peripheral surface except one end surface of the dielectric block 35 in which one opening of the through hole 36 is located, and the outer conductor 38 is formed in the inner conductor 37 at the other opening of the through hole 36. Connected with.

In the second dielectric resonators 3, 4 and 5 thus constructed, the hot conductors 16c and 16 in which the inner conductors 37 are exposed from the solder resist 17 shown in FIG.
d and 16e are soldered via lead terminals 9, 10 and 11 and capacitors 6, 7 and 8, respectively, and each outer conductor 38 is soldered to the ground electrode 16f exposed from the solder resist 17 for insulation. It is attached to the substrate 1.

As shown in FIG. 12, the capacitors 6, 7 and 8 are formed by forming capacitor electrodes 40 and 41 on both surfaces of a ceramic body 39, and one of the electrodes 41 is the hot electrodes 16c and 16d. , 16e, respectively, and attached to the insulating substrate 1. The lead terminals 9, 10, 11 are connected to the other electrodes 40 of the capacitors 6, 7, 8 respectively.

The coils 12, 13 and 14 are of a winding type in which a conductor wire is wound several turns, and the hot electrode 1 exposed from the solder resist 17 shown in FIG.
Soldered between 6a and 16c, between 16c and 16d, and between 16d and 16e are attached to the insulating substrate 1. In this way, the second dielectric resonators 3, 4, 5, capacitors 6, 7, 8 and coils 12, 13, 14 mounted on the insulating substrate 1 and the hot electrodes 16c, 16d,
A filter (a filter formed between the antenna terminal and the Tx terminal) on the transmission circuit side of the equivalent circuit shown in FIG. 2 is formed by the capacitance formed between 16e and the ground electrode 18.

The metal case 15 includes coils 12, 1
It is arranged so as to cover portions 3 and 14, and is attached to the insulating substrate 1 by being soldered to the ground electrode 16h shown in FIG. Windows 15a, 1 are provided on the upper surface of the metal case 15.
5b, 15c are formed, and after the metal case 15 is attached to the insulating substrate 1, the windows 15a, 15b, 1b thereof are formed.
The filter characteristic is adjusted by changing the winding interval of the coils 12, 13 and 14 from 5c.

In the above embodiment, the solder resist 17 formed on the first surface of the insulating substrate 1 is used.
Consists of two layers of solder resists 17a and 17b, but it is also possible to have three layers or more. Further, the solder resist 17 on the first surface is made up of the ground electrodes 16f, 16
Although formed on a part of g and 16h, the hot electrodes 16a, 16b and 16c overlap the outer conductor 32 of the first dielectric resonator 2 and the outer conductor 38 of the second dielectric resonators 3 and 4, respectively.
It is also possible to form only a part. However,
If formed on the ground electrodes 16f, 16g, 16h, for example, the first and second dielectric resonators 2, 3, 4,
Since the soldering positions of the outer conductors 32 and 38 of No. 5 with respect to the ground electrode 16f are defined at predetermined positions, it contributes to stabilization of the filter characteristics. In the above embodiment, the solder resist 17a of the first layer is also used.
The second layer solder resist 17b and the second layer solder resist 17b have different colors, but they can be formed of the same color material unless it is necessary to visually confirm.

The dielectric filter constructed as described above has a hot electrode portion that overlaps the outer conductor of the dielectric resonator, specifically, the hot electrode 16a that overlaps the outer conductor 32 of the first dielectric resonator 2. , 16b and the hot electrodes 16c overlapping the outer conductors 38 of the second dielectric resonators 3 and 4, at least two layers of solder resists 17a and 17b are used as the insulating substrate, and therefore the electrodes are provided only on the surface. Even with a patterned insulating substrate, a dielectric filter similar to that using a multi-layer substrate can be constructed, and since the thickness of the substrate can be reduced, the height can be made lower than that using a multi-layer substrate. It will be possible. In addition, an insulating substrate with an electrode pattern formed only on the surface is less expensive than a multilayer substrate with an electrode pattern formed inside, and solder resist formation is extremely easy to mass-produce and can be formed at low cost. The cost can be reduced compared to the conventional dielectric filter.

FIG. 13 is a perspective view of another embodiment of the dielectric filter according to the present invention. This dielectric filter
Dielectric resonance is achieved by mounting a dielectric resonator on an insulating substrate with an electrode pattern formed only on the surface and connecting the terminal electrode formed on the dielectric resonator to the terminal electrode formed on the insulating substrate. The position of the terminal electrode of the container is substantially changed. That is, in FIG. 13, the dielectric filter is configured by mounting the dielectric resonator 52 on the insulating substrate 51.

The insulating substrate 51 is formed of the same wiring substrate material as that of the insulating substrate 1 in the above-described embodiment, and the first surface, which is the mounting surface of the dielectric resonator 52, has a structure as shown in FIG. An electrode pattern 53 including a pair of hot electrodes 53a and 53b is formed, and a solder resist 54 (hatched portion) is formed on the electrode pattern 53.
Further, as shown in FIG. 15, an electrode pattern 55 including a pair of terminal electrodes 55a and 55b is formed on the second surface which is the opposite surface thereof. Although the ground electrode is actually formed adjacent to the electrode pattern 53 on the first surface, the illustration is omitted. The electrode pattern 53 on the first surface corresponds to the connection electrodes CE21, C on the side surface of the insulating substrate 51.
It is connected to the electrode pattern 55 on the second surface via E22. These electrode patterns 53 and 55 are formed by using the same material and method as the electrode patterns 16 and 18 of the above-described embodiment.

The solder resist 54 on the electrode pattern 53 is the first layer solder resist 54a having the pattern shown in FIG. 16 and the first layer solder resist 5
A second pattern having the pattern shown in FIG. 17 formed on 4a.
It is formed with the solder resist 54b of the first layer. In this embodiment, the first-layer solder resist 54a and the second-layer solder resist 54a
The pattern is the same as that of the solder resist 54b of the layer, and the thickness thereof is formed within the range of 25 to 45 μm. The first-layer and second-layer solder resists 54a and 54b are formed by the same material and method as those in the above-described embodiment. In addition, the solder resist 5
4 as described above with two layers of solder resist 54a, 54b
Is formed by increasing the thickness of the solder resist in the same manner as in the above-described embodiment to obtain sufficient withstand voltage characteristics between the outer conductor and the hot electrode, which will be the ground potential of the dielectric resonator described later. Is to get. The solder resist 54 may have a structure of three or more layers, as in the above embodiment.

The dielectric resonator 52 is constructed as shown in FIG. That is, this dielectric resonator 52 has the same configuration as that shown in FIG. 10, and four through holes 58, 59, 60, 61 are provided along the longitudinal direction of the rectangular parallelepiped dielectric block 57. The inner conductor 6 is formed in these through holes 58, 59, 60, 61.
2, 63, 64 and 65 are formed. Terminal electrodes 66 and 67 are formed on the bottom surface of the dielectric block 57 facing the inner conductors 62 and 65 of the through holes 58 and 61 at both ends.
Capacitances are formed between the terminal electrode 66 and the inner conductor 62 and between the terminal electrode 67 and the inner conductor 65, respectively. Further, an outer conductor 68 is formed on the entire outer peripheral surface of the dielectric block 57 except for the periphery of the terminal electrodes 66 and 67, and the outer conductor 68 has through holes 58, 59, 60 and 61.
Are connected to the inner conductors 62, 63, 64, 65 at both openings. The inner conductors 62, 63, 64, 65
Has an annular gap formed along the inner peripheral surface in the vicinity of one opening, and is in a discontinuous state in each through hole 58, 59, 60, 61.

The dielectric resonator 52 thus configured
14 are soldered to the hot electrodes 53a and 53b whose terminal electrodes 66 and 67 are exposed from the solder resist 54 shown in FIG. 14, respectively, and the outer conductor 68 is soldered to a ground electrode (not shown) to form the insulating substrate 51. Is attached to.

The dielectric filter constructed as described above is
Hot electrode 53 overlapping the outer conductor 68 of the dielectric resonator 52
At least two layers of solder resist 54 on the portions a and 53b
Since the insulating substrate on which a and 54b are formed is used, even if the insulating substrate has the electrode pattern formed only on the surface, a dielectric filter substantially similar to that using a multilayer substrate can be constructed, and Since the thickness can be reduced, it is possible to reduce the height as compared with the one using a multilayer substrate. In addition, an insulating substrate with an electrode pattern formed only on the surface is less expensive than a multilayer substrate with an electrode pattern formed inside, and solder resist formation is extremely easy to mass-produce and can be formed at low cost. The cost can be reduced compared to the conventional dielectric filter.

[0044]

As described above, according to the inventions of claims 1 to 3, it is sufficient to form at least two layers of solder resist on the hot electrode portion on the electrode pattern, which overlaps at least the outer conductor of the dielectric resonator. Since a high withstand voltage characteristic is obtained, a dielectric filter can be configured using an insulating substrate having an electrode pattern formed only on the surface,
Since such an insulating substrate can be made thin, the height can be reduced. In addition, an insulating substrate having an electrode pattern formed only on the surface is inexpensive, and a solder resist can be inexpensively formed, so that the cost of the dielectric filter can be reduced.

According to the second aspect of the invention, since the filter circuit is formed by the dielectric resonator and the lumped constant circuit element, various filter circuits can be formed.

Further, according to the invention of claim 3, since the solder resists of the respective layers have different colors, it is possible to visually confirm whether or not a predetermined solder resist is formed.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing only a metal case of a dielectric filter according to the present invention.

FIG. 2 is an equivalent circuit diagram of the dielectric filter shown in FIG.

FIG. 3 is a plan view of an insulating substrate in which a solder resist is formed on an electrode pattern formed on a first surface.

FIG. 4 is a back view of an insulating substrate in which a solder resist is formed on an electrode pattern formed on a second surface.

FIG. 5 is a plan view of an insulating substrate having an electrode pattern formed on a first surface.

FIG. 6 is a back view of an insulating substrate having an electrode pattern formed on a second surface.

FIG. 7 is a first diagram formed on the electrode pattern on the first surface.
It is a figure which shows the pattern of the solder resist of a layer.

FIG. 8 shows a second electrode formed on the electrode pattern on the first surface.
It is a figure which shows the pattern of the solder resist of a layer.

FIG. 9 is a diagram showing a pattern of a solder resist formed on the electrode pattern on the second surface.

10 is a perspective view of a first dielectric resonator used in the dielectric filter of FIG. 1. FIG.

11 is a perspective view of a second dielectric resonator used in the dielectric filter of FIG.

FIG. 12 is a perspective view of a capacitor used in the dielectric filter of FIG.

FIG. 13 is a perspective view of a dielectric filter according to another embodiment of the present invention.

FIG. 14 is a plan view of an insulating substrate in which a solder resist is formed on the electrode pattern formed on the first surface.

FIG. 15 is a back view of an insulating substrate having an electrode pattern formed on a second surface.

FIG. 16 is a diagram showing a pattern of a first layer solder resist formed on the electrode pattern formed on the first surface.

FIG. 17 is a diagram showing a pattern of a second layer solder resist formed on the electrode pattern formed on the first surface.

18 is a perspective view of a dielectric resonator used in the dielectric filter of FIG.

FIG. 19 is a cross-sectional view of essential parts of a conventional dielectric filter.

20 is a perspective view of a dielectric resonator used in the dielectric filter of FIG.

FIG. 21 is a sectional view of an essential part of another conventional dielectric filter.

22 is a perspective view of a dielectric resonator used in the dielectric filter of FIG.

FIG. 23 is a cross-sectional view of an essential part of another conventional dielectric filter.

24 is a perspective view of a dielectric resonator used in the dielectric filter of FIG.

[Explanation of symbols]

 1 Insulating Substrate 2 First Dielectric Resonator 3, 4, 5 Second Dielectric Resonator 6, 7, 8 Capacitor 9, 10, 11 Lead Terminal 12, 13, 14 Coil 15 Metal Case 16, 18 Electrode Pattern 17, 19 Solder resist 51 Insulating substrate 52 Dielectric resonator 53, 55 Electrode pattern 54 Solder resist

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area H05K 1/18 H05K 1/18 J 3/28 3/28 B

Claims (3)

[Claims] 1. A dielectric material comprising a dielectric resonator having an outer conductor formed on an outer peripheral surface thereof, which is mounted on an insulating substrate having an electrode pattern formed only on a surface thereof so as to overlap with a hot electrode portion of the electrode pattern. A dielectric filter, characterized in that at least two layers of solder resist are formed on at least a hot electrode portion on the electrode pattern which overlaps with an outer conductor of the dielectric resonator. 2. The dielectric filter according to claim 1, wherein a lumped constant circuit element is provided on the insulating substrate, and a predetermined filter circuit is formed by the dielectric resonator and the lumped constant circuit element. Characteristic dielectric filter. 3. The dielectric filter according to claim 1, wherein the solder resists have colors different from each other.