JPH09284005A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deviation in the position of a dielectric filter in the reflow soldering to a printed circuit board. SOLUTION: Resonator holes 16a, 16b acting like resonance elements are penetrated between end faces of a dielectric 10 of the dielectric filter 1A. A ground electrode 11A made of a conductor film is formed on an outer surface of the dielectric block 10, and signal input output terminals 12a, 12b insulated from the ground electrode 11A are provided to a rear 33 and a side face 32a in succession to the rear 33. In the case the rear 33 of the dielectric block 10 is divided into four quadrants, thermal correction sections 13a, 13b with a calorific capacity nearly equal to the signal input output terminals 12a, 12b are provided to positions nearly corresponding to the signal input output terminals 12a, 12b on the quadrants where the signal input output terminals 12a, 12b are not in existence. Thus, the calorific capacity of the circumferential components of the dielectric filter 1A is balanced and then deviation of the positions of the components of the dielectric filter 1A in the case of reflow soldering is not caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter for passing or blocking a high-frequency signal in a specific frequency band, and more particularly, to a method of forming a resonator hole in a rectangular parallelepiped dielectric block and an outer surface of the dielectric block. And a dielectric filter having a structure in which a conductor film is provided on the inner wall surface of the resonator hole.

[0002]

2. Description of the Related Art As one of conventional dielectric filters of this type, a part of a conductive film provided on an outer surface of a dielectric block is formed so as to be insulated from most of the remaining conductive films. Japanese Patent Application Laid-Open No. H5-1673 discloses a type in which a portion insulated from most of the remaining conductive film is used as an input / output terminal for a high frequency signal.
No. 10 discloses this. This type of dielectric filter is characterized in that the input / output terminals can be directly connected to a pattern on a printed circuit board. Hereinafter, a dielectric filter of the same type as that disclosed will be described with reference to FIGS. FIG. 4 shows a dielectric filter 1 according to the prior art.
It is a perspective view of B. FIG. 5 is a front view of a printed circuit board 2B on which the dielectric filter 1B is mounted. FIG. 6 is a perspective view showing a state where the dielectric filter 1B is mounted on the printed circuit board 2B.

[0003] Referring to FIG. 4, a dielectric filter 1B is formed on a dielectric block 10 of a high dielectric constant ceramic having a substantially rectangular parallelepiped shape. In FIG. 4, the dielectric block 1
Numeral 0 is covered with the ground electrode 11B, the input / output terminals 12a and 12b and the short-circuit surface 15a, which are conductor films formed on the outer surface by copper plating, silver plating, solder plating, or the like, and only a dotted pattern portion is visible. Resonator holes 16a and 16b penetrate between two end faces of dielectric block 10 (one end face has open face 14a and short-circuit face 15b), and the inner wall faces of these resonator holes 16a and 16b Also, a conductor film is provided. This dielectric filter 1B is a two-stage filter using two resonator holes 16a and 16b as resonance elements. The resonator hole 16a causes electromagnetic coupling between the input / output terminal 17a and the resonator hole 16b and a high-frequency signal. The resonator hole 16b is connected to the resonator hole 16a and the input / output terminal 17b.
And a high frequency signal. A dielectric filter having an electromagnetic field coupling hole at an intermediate point between the resonator holes 16a and 16b of the dielectric block 10 is often used.

The dielectric filter 1B has input / output terminals 12a and 12b insulated from the ground electrode 11B by cutouts 17a and 17b where no conductor film is formed.
Are input terminals or output terminals of high frequency signals.
In the dielectric filter 1B, one end face of the resonator hole 16a has an open face 14 that does not constitute the ground electrode 11B.
In the case of a, the same end surface of the resonator hole 16b is a short-circuit surface 15b constituting the ground electrode 11B. The dielectric filter 1B has a back surface 33 close to the short-circuit surface 15b and the like.
The input / output terminals 12a and 12b are arranged on a side surface 32a (or another side surface) following the back surface 33, respectively. These input / output terminals 12a and 12b have the same shape and area.

[0005] The dielectric filter 1B shown in FIG. 4 is reflow soldered on the back surface 33 side to the ground surface 21B side of the printed circuit board 2B shown in FIG. Now, the back surface 33 of the dielectric filter 1B
, The x-axis and the y-axis intersect at the center point O1, and the printed circuit board 2B also defines the same center point O2, the x-axis and the y-axis. Then, the coordinates of the printed circuit board 2B shown in FIG. 5 are moved counterclockwise from the upper right in the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant.
When the quadrant is divided into four quadrants, the dielectric block 10 shown in FIG.
On the back surface 33, the quadrant in which the input / output terminal 12b is located becomes the first quadrant, and then becomes the second, third, and fourth quadrants in a clockwise direction. Therefore, the quadrant where the input / output terminal 12a is located is the third quadrant.

Referring to FIG. 5, the printed circuit board 2B has a ground surface 21B, which is a conductor film obtained by plating a copper film with gold,
The terminal portions 22a and 22b are formed on the surface of a dielectric substrate 29 made of resin or plastic. The maximum outer shape of the ground surface 21B is slightly larger than the maximum outer shape of the back surface 33 of the dielectric filter 1B. That is, the printed circuit board 2
The area within the filter mounting section 30 indicated by the two-dot chain line on B is the mounting section for the dielectric filter 1B. The terminal portion 22a is a peeled portion 27a on which no conductive film is formed on the dielectric substrate 29.
The terminal portion 22b is insulated from the ground surface 21B by the
Is also insulated from the ground surface 21B by a similar peeling portion 27b.

Referring to FIG. 6, ground electrode 11B and input / output terminals 12a and 12b formed on back surface 33 of dielectric filter 1B are reflow soldered to ground surface 21B and terminal portions 22a and 22b of printed circuit board 2B, respectively. Is done. In FIG. 6, the dielectric filter 1B
Is soldered to the printed circuit board 2B with the solders 35d, 35f, and 35g raised on the side surfaces 32a and solder (not shown), and the upper surface 31 of the dielectric filter 1B appears on the front surface. Solder 35d is dielectric filter 1B
Terminal 12a of the printed circuit board 2B
Similarly, solders 35f and 35g solder the ground electrode 11B (not shown) and the ground surface 21B. Before soldering, the solders 35d, 35f and 35g are grounded on the ground surface 21B of the printed circuit board 2B.
And the terminal portions 22a and 22b.

In the above-described reflow soldering, the dielectric filter 1B is pulled from the molten state to the position of the solder where the dielectric filter 1B cools down quickly and is fixed. The fixing time of the solders 35d, 35f, 35g and the like becomes shorter as the heat capacity of the portions where these solders are located is smaller. Here, the conductor film shape and the area of the terminal portion 22a located in the first quadrant of the printed circuit board 2B and the terminal portion 22b located in the third quadrant are the same as those of the terminal portion 22a and the terminal portion 22b of the printed circuit board 2B. It is different from the positions corresponding to the four quadrants, that is, the portions A and B, which are symmetrical with respect to the x axis or the y axis. Therefore, the heat capacity at the positions of the terminal portions 22a and 22b (that is, the positions of the input / output terminals 12a and 12b) is the same as the heat capacity of the A portion and the B portion (that is, the ground electrode 11B at the position corresponding to the A portion and the B portion). It turns out that they are clearly different.

Now, the heat capacity of the portions A and B is equal to that of the terminal 2
If it is smaller than the heat capacity at positions 2a and 22b,
Since the solder 35f of the portion A and the solder at the point symmetrical position of the portion A with respect to the center point O2 are fixed earlier than the solder 35d of the terminal portion 22a and the solder at the position of the terminal portion 22b, the dielectric filter 1B has A1 and A2. In the direction of A2, that is, in the counterclockwise direction with respect to the filter mounting portion 30 of the printed circuit board 2B, it is fixed. Conversely, when the heat capacities of the portions A and B are larger than the heat capacities at the terminals 22a and 22b, the dielectric filter 1B
1 and A2 are fixed in a direction opposite to that of A2, that is, in a clockwise direction with respect to the filter mounting portion 30 of the printed circuit board 2B. The heat capacities of the terminal portions 22a and 22b, the A portion and the B portion vary depending on the materials and dimensions of the dielectric filter 1B and the printed board 2B.

[0010]

When the above dielectric filter is reflow-soldered to a printed circuit board, the dielectric filter is displaced from a first set place on the printed circuit board. There is a problem that the terminals of the substrate may be connected (short-circuited) and the function of the dielectric filter may not be achieved.

Accordingly, it is an object of the present invention to provide a dielectric filter which can prevent a displacement from a set position on a printed circuit board during reflow soldering to the printed circuit board.

[0012]

DISCLOSURE OF THE INVENTION The dielectric filter of the present invention is provided on a dielectric block having a substantially rectangular parallelepiped shape, a through hole penetrating between two end faces of the dielectric block, and an inner wall surface of the through hole. A resonator hole having a conductor film, a ground electrode formed by applying a conductor film to the outer surface of the dielectric block, and a conductor film formed on the back surface of the dielectric block and insulated from the ground electrode. And a rear surface of the dielectric block is divided into four quadrants, the input / output terminals are provided at locations substantially corresponding to the input / output terminals in the quadrant where the input / output terminals do not exist. The thermal correction unit further includes a conductive film having a substantially equal heat capacity.

One of the dielectric filters may have a structure in which the thermal correction section has substantially the same area as the input / output terminals and is connected to the ground electrode by a thin conductor film.

Another one of the dielectric filters may have a configuration in which the input / output terminal and the thermal correction section are also formed on a side surface of the dielectric block which is continuous with a back surface of the dielectric block.

[0015] The dielectric filter according to the present invention further includes a heat compensator formed of a conductive film having substantially the same heat capacity as the input / output terminal at a location substantially corresponding to the input / output terminal in the quadrant where the input / output terminal does not exist. By doing so, the heat capacity of the conductor film on the back surface of the dielectric filter and the printed circuit board that is the counterpart of reflow soldering can be balanced in each quadrant, and the solder fixing time during reflow soldering is the same in each quadrant. As a result, it is possible to prevent displacement from the initial setting position on the printed circuit board.

[0016]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a dielectric filter 1A according to one embodiment of the present invention. FIG. 2 is a front view of a printed circuit board 2A on which the dielectric filter 1A is mounted. FIG.
FIG. 3 is a perspective view showing a state in which the dielectric filter 1A is mounted on a printed circuit board 2A.

The dielectric filter 1A shown in FIG. 1 has thermal correction sections 13a and 13b except that a part of the ground electrode 11A of the above-described dielectric filter 1B is removed by cutouts 18a and 18b.
b and bridge portions 19a and 19b. Hereinafter, only these changes will be described.

The thermal correction section 13a is a conductor film having substantially the same shape and area as the input / output terminal 12a, and is provided at a symmetrical position with respect to the x-axis of the input / output terminal 12a. In addition, it can be said that the heat correction unit 13a has substantially the same shape and area as the input / output terminal 12b, and is provided at a symmetric position with respect to the y-axis of the input / output terminal 12b. The notch 18a has the same basic configuration and the like as the notch 17a for forming the input / output terminal 12a, but has six thin conductors for connecting the heat compensator 13a to the ground electrode 11A. The bridge portion 19a, which is a film, is omitted, and is separated into six portions.
The bridge portion 19a is a connection portion that keeps the potential of the heat correction portion 13a at the ground electrode 11A, and reduces the variation in electric characteristics of the dielectric filter 1A from the dielectric filter 1B due to the formation of the cutout portion 18a. Note that the bridge 19a can be removed. In this case, the bridge 29a of the printed circuit board 2A, which will be described later, uses the heat compensator 13a.
And the connection with the ground electrode 11A is maintained.

The thermal correction section 13b is a conductor film having substantially the same shape and area as the input / output terminal 12b, and is provided at a symmetrical position with respect to the x-axis of the input / output terminal 12b. Thermal correction unit 1
3b also has substantially the same shape and area as the input / output terminal 12a, and can be said to be provided at a symmetric position with respect to the y-axis of the input / output terminal 12a. A cut portion 18b and a bridge portion 19b are provided in association with the heat correcting portion 13b.
b and the bridge 19b have the notch 1
8a and the bridge portion 19a.

Since the heat compensators 13a and 13b have substantially the same configuration as the input / output terminals 12a and 12b, these four have substantially the same heat capacity. Further, the heat correction unit 13a is located at a corresponding position on the fourth quadrant with respect to the input / output terminal 12a on the first quadrant, and the heat correction unit 13b is connected with the second input / output terminal 12b on the third quadrant. At the corresponding position in the quadrant. Therefore, the input / output terminals 12a, 12b
In addition, the thermal correction units 13a and 13b are arranged in a balanced manner in all quadrants obtained by dividing the back surface 33 of the dielectric block 10 into four quadrants.

In the printed circuit board 2A of FIG. 2, a part of the ground surface 21B of the above-described printed circuit board 2B is separated by a peeling portion 28a.
The correction parts 23a and 23b and the bridge parts 29a and 29b are formed except for the parts 28 and 28b. These stripped portions 28a, 28b, correction portions 23a, 23b, and bridge portions 29a, 29b correspond to the formation of cut portions 18a, 18b, thermal correction portions 13a, 13b, and bridge portions 19a, 19b of dielectric filter 1A, respectively. It is formed. Hereinafter, only these changes will be described.

The correction portion 23a has substantially the same shape and area as the terminal portion 22a, and is provided at a symmetrical position with respect to the x axis of the terminal portion 22a. It can be said that the correction portion 23a has substantially the same shape and area as the terminal portion 22b, and is provided at a symmetrical position with respect to the y-axis of the terminal portion 22b. Peeling part 2
8a has the same basic configuration as the peeling portion 27a for forming the terminal portion 22a in shape and the like, but a bridge portion 29a which is two thin conductor films for connecting the correcting portion 23a to the ground surface 21A. And is separated into four parts. The correction section 23b has substantially the same shape and area as the terminal section 22b, and is provided at a symmetric position with respect to the x-axis of the terminal section 22b. It can be said that the correction section 23b also has substantially the same shape and area as the terminal section 22a, and is provided at a symmetric position with respect to the y-axis of the terminal section 22a. A peeling section 28b and a bridge section 29b are provided in association with the correction section 23b, and the configurations and functions of the peeling section 28b and the bridge section 29b are the same as those of the peeling section 28a and the bridge section 29a, respectively. Since the correction parts 23a and 23b have substantially the same configuration as the terminal parts 22a and 22b, these four have substantially the same heat capacity. The correction unit 23a
And 23b are located at positions where they are reflow-soldered to the thermal correctors 13a and 13b of the dielectric filter 1A.

Referring to FIG. 3, ground electrode 11A and input / output terminals 12a and 12b formed on back surface 33 of dielectric filter 1A are connected to ground surface 21A and terminal portions 22a and 22b of printed circuit board 2A by reflow soldering, respectively. Attached. In FIG. 3, the back surface 33 of the dielectric filter 1 </ b> A has the solder 3 on the side surface 32 a as well.
5a, 35b, 35c, 35d, 35e and solder (not shown) are soldered to the printed circuit board 2A, and the upper surface 31 of the dielectric filter 1A appears on the surface. The solders 35a and 35d are connected to the thermal correction unit 1 of the dielectric filter 1A.
3a, the correction portion 23a of the printed circuit board 2A, the input / output terminal 12a, and the terminal portion 22a, and similarly, the solders 35a, 35c, and 35e solder the ground electrode 11A (not shown) and the ground surface 21A. doing. The solders 35a to 35e are prepared on the ground surface 21A of the printed circuit board 2A, the terminals 22a and 22b, and the correction units 23a and 23b before soldering.

In the above-described reflow soldering, the input / output terminals 12a and 12b of the dielectric filter 1A, the thermal correctors 13a and 13b, and the corresponding terminals 22a and 22b of the printed circuit board 2A and the correctors 23a and 2b, respectively.
3b is the dielectric filter 1A and 4 of the printed circuit board 2A.
Since the solders 35a, 35b, 35c, 35d, 35e and the like are fixed at almost the same time because they are arranged in a well-balanced manner in each of the divided quadrants. Accordingly, the dielectric filter 1A does not shift from the position initially set on the printed circuit board 2A, and the ground electrode 11A of the dielectric filter 1A is connected to the terminal portions 22a and 22b of the printed circuit board 2A. Can be eliminated.

The thermal correction unit 13 of the dielectric filter 1A
a and 13b may have a shape and a divided state in which heat capacities are substantially the same at positions substantially corresponding to the input / output terminals 12a and 12b, and the heat correction unit in the present invention is not limited to the above-described shape. .

Also, according to the present invention, the input / output terminals 12a and 12b are provided in the first and third quadrants of the back surface 33, such as the dielectric filter 1A of the embodiment shown in FIGS.
It is not limited to the format provided with. That is, JP-A-5-167
As disclosed in Japanese Patent Application Publication No. 310-310, in a dielectric filter of a type having input / output terminals in the first and second quadrants on the back surface, the above-described thermal correction units 13a and 13b are provided in the third and fourth quadrants where no input / output terminals exist. By providing a thermal correction unit equivalent to that described above, it is possible to prevent misalignment from an initially set position during reflow soldering to a printed circuit board.

[0027]

As described above, the dielectric filter of the present invention, when the back surface of the dielectric block is divided into four quadrants, almost corresponds to the input / output terminals in the quadrant where there are no input / output terminals for high frequency signals. Since the thermal correction section formed of a conductive film having substantially the same heat capacity as the input / output terminal is provided at a location where the input / output terminal is mounted, it is possible to prevent a displacement from an initially set position at the time of reflow soldering to a printed circuit board, and There is an effect that the function of the filter can be sufficiently exhibited.

[Brief description of drawings]

FIG. 1 shows a dielectric filter 1 according to an embodiment of the present invention.
It is a perspective view of A.

FIG. 2 is a printed circuit board 2 on which a dielectric filter 1A is mounted.
It is a front view of A.

FIG. 3 is a perspective view showing a mounting state of a dielectric filter 1A on a printed circuit board 2A.

FIG. 4 is a perspective view of a conventional dielectric filter 1B.

FIG. 5 is a printed circuit board 2 on which a dielectric filter 1B is mounted.
It is a front view of B.

FIG. 6 is a perspective view showing a state in which a dielectric filter 1B is mounted on a printed circuit board 2B.

[Explanation of symbols]

 1A Dielectric filter 10 Dielectric block 11A Ground electrode 12a, 12b Input / output terminal 13a, 13b Thermal correction unit 14a, 14b Open surface 15a, 15b Short-circuit surface 16a, 16b Resonator hole 17a, 17b, 18a, 18b Notch 19a , 19b Bridge portion 31 Top surface 31a Side surface 2A Printed circuit board 21A Ground surface 22a, 22b Terminal portion 23a, 23b Correction portion 27a, 27b, 28a, 28b Stripping portion 29a, 29b Bridge portion 30 Filter mounting portion 35a to 35e Solder

Claims (3)

[Claims] 1. A dielectric block having a substantially rectangular parallelepiped shape, a through hole penetrating between two end faces of the dielectric block, and a resonator hole having a conductor film formed on an inner wall surface of the through hole, and the dielectric body. In a dielectric filter comprising a ground electrode formed by applying a conductor film to the outer surface of the block, and an input / output terminal formed of a conductor film on the back surface of the dielectric block and insulated from the ground electrode, When the back surface of the dielectric block is divided into four quadrants, a thermal compensator formed of a conductive film having substantially the same heat capacity as that of the input / output terminals at a position substantially corresponding to the input / output terminals of the quadrant where the input / output terminals do not exist. A dielectric filter, further comprising: 2. The dielectric filter according to claim 1, wherein the thermal correction unit has substantially the same area as the input / output terminal and is connected to the ground electrode with a thin conductor film. 3. The input / output terminal and the thermal compensator are
The dielectric filter according to claim 1, wherein the dielectric filter is also formed on a side surface of the dielectric block that is continuous with a back surface of the dielectric block.