JPH0615305U - Dielectric filter - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a dielectric filter that suppresses variations in mounting strength of input / output terminals and is easy to assemble. [Configuration] This dielectric filter 1 includes a plurality of resonators 5,
Input / output capacitors 15 and 16 in which the inner electrode 18 is connected to the inner conductor 10 and the other outer electrode 19 is connected to the input / output terminal 20 are arranged in the filter body 2 to which 6 is joined.
A hole 23 for accumulating solder is formed in a joint portion 22 of the input / output terminal 20 that is joined to the outer electrode 19 of the capacitors 15 and 16.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a dielectric filter, particularly a surface mount type dielectric filter.

[0002]

[Prior art]

 For example, a surface-mounted dielectric filter that can be directly mounted on a circuit board is used as a high frequency filter of a communication device. This surface mount type dielectric filter includes a plurality of dielectric resonators, an input / output capacitor connected to a predetermined resonator, a substantially L-shaped input / output terminal connected to the capacitor, and a plurality of dielectric resonators. It is equipped with a metal case for storing.

The dielectric resonator has a rectangular parallelepiped shape made of a dielectric ceramic, has a through hole extending from one end face to the other end face, and an inner conductor is formed on the inner wall of the through hole. Has been done. An outer conductor is formed on the outer peripheral surface except one end surface (open end surface) where the through hole opens. Further, a recess is formed on the open end face side to accommodate the input / output capacitor.

Further, a coupling groove formed by removing a part of the outer conductor and the dielectric ceramic is formed on the side surface of each resonator that is joined to the adjacent resonator.

The dielectric filter is achieved by the following assembly process.

First, an input / output capacitor is soldered to the recess of the dielectric resonator in which the input / output capacitor is arranged.

Next, cream solder is applied to the case, a plurality of dielectric resonators are brought into contact with each other, and the case is placed on the case.

Next, cream solder is applied to the upper surface of the input / output capacitor bonded to the predetermined dielectric resonator. Then, the input / output terminals are pressed against the upper surface of the capacitor, and after positioning, soldering is performed using a reflow furnace, etc., and the case and the dielectric resonator are soldered and the input / output capacitor and input / output terminal are soldered. .

The reason why the input / output capacitor is soldered to the depression for the first time and then the input / output terminals are further soldered is that when the cream solder is applied to the upper surface of the input / output capacitor, the input / output capacitor is first soldered. This is to prevent the input / output capacitor from adhering to the tip of the nozzle when cream solder for soldering the input / output terminals is supplied from the supply nozzle unless it is bonded and fixed.

[0010]

[Problems to be solved by the device]

 In the above dielectric filter, when the input / output terminal is soldered to the input / output capacitor, the input / output capacitor must be soldered to the resonator first, and at least 2 is required before the dielectric filter is formed. There has been a problem that the manufacturing process is complicated because the solder joint needs to be heat-treated once.

Further, although cream solder is applied between the input / output capacitor and the input / output terminal, the cream solder does not spread over the entire electrode surface of the input / output capacitor during the reflow process, and is transmitted through the lead part of the input / output terminal. There is a case where it leaks out to the outside. At this time, the mounting strength of the input / output terminals is insufficient, which causes misalignment during mounting on the circuit board or during use, resulting in poor connection.

An object of the present invention is to provide a dielectric filter which is easy to assemble, has a strong connection strength between an input / output capacitor and an input / output terminal, and has high reliability.

[0013]

[Means for Solving the Problems]

 A dielectric filter according to a first aspect of the present invention comprises a capacitor between two dielectric resonators forming a filter section and an input / output terminal, and one capacitor electrode of the capacitor is an inner conductor of the dielectric resonator. In the dielectric filter, which is connected to the capacitor electrode and the other capacitor electrode is connected to the input / output terminal, the input / output terminal is provided with a solder pool hole at a joint part to be joined to the capacitor electrode. ing.

A dielectric filter according to a second aspect of the invention is the dielectric filter of the first aspect of the invention, in which the lower portion of the solder pool hole of the joint portion is formed with a cut-and-raised portion toward the outside.

[0015]

[Action]

 In the dielectric filter according to the first invention, one of the capacitor electrodes is joined to the inner conductor of the dielectric resonator. Furthermore, the joint portion of the input / output terminal is joined to the other capacitor electrode. Since the solder joint holes are formed at the joints of the I / O terminals, the solder supplied from the front side of the joint portions of the I / O terminals penetrates through the solder reservoir holes and between the I / O terminals and the capacitor electrodes. Then, a solder layer is formed. Therefore, the capacitor electrode and the input / output terminal can be solder-bonded over the entire electrode surface without applying solder between the capacitor electrode and the input / output terminal. Therefore, it is possible to suppress variations in mounting strength of the input / output terminals, and it is possible to obtain a highly reliable dielectric filter.

Also, since soldering can be performed with the input / output terminals being pressed from above the input / output capacitor, the solder solder is applied to the depressions of the dielectric resonator and the subsequent assembly is performed continuously. An easy assembly is achieved, obtaining a dielectric filter through a reflow oven.

In the dielectric filter according to the second aspect of the invention, the solder applied to the solder reservoir holes is held by the cut and raised portions. Therefore, it is possible to prevent the solder from flowing out at the time of applying the cream solder or in the reflow process. As a result, the soldering strength is high and the cream solder application operation is facilitated.

[0018]

【Example】

 Hereinafter, the dielectric filter of the present invention will be described in detail with reference to the drawings. 1 is an external perspective view of a dielectric filter of the present invention, FIG. 2 is a cross-sectional view taken along the line I-I in FIG. 1, and FIG. 3 is an exploded perspective view. In the figure, an example in which two resonators, which is a basic structure of a dielectric filter, are joined together will be described.

In the figure, the dielectric filter 1 is mainly composed of a filter body 2, upper and lower cases 3 and 4 for housing the filter body 2, and input / output terminals 20.

The filter body 2 is formed by joining two independent resonators 5 and 6, and further input / output capacitors 15 and 16 are arranged.

As shown in FIG. 2, one resonator 5 is composed of a block 7 made of a dielectric ceramic having a rectangular parallelepiped shape, and a cylindrical through hole 8 is formed so as to open at opposite end surfaces of the dielectric block 7. Are formed. In addition, a recess (hereinafter referred to as a cavity) 9 in which the input / output capacitors 15 and 16 are arranged is formed on one end surface side of the through hole 8.

A series of inner conductors 10 are attached to the inner peripheral surface of the through hole 8 and the inner peripheral surface of the cavity 9. An outer conductor 11 is attached to the outer peripheral surface of the dielectric block 7 except for the open end surface on the cavity 9 side. The outer conductor 11 is short-circuited with the inner conductor 10 on the other end surface (short-circuited end surface) of the dielectric block 7. Further, as shown in FIG. 3, the resonator 5 extends in a direction orthogonal to the through hole 8 on the side surface adjacent to the resonator 6, and the outer conductor 11 and a part of the dielectric ceramic are removed. It has a square groove 12.

The resonator 6 is configured similarly to the resonator 5, and has a square groove 13 on the surface adjacent to the resonator 5.

Therefore, by joining the resonators 5 and 6, the groove 12 on the resonator 5 side and the groove 13 on the resonator 6 side correspond to each other to form the coupling hole 14. In the filter body 2, the electromagnetic field coupling generated in the coupling hole 14 constitutes a filter in which the two resonators 5 and 6 are connected. The pass band width of this filter can be adjusted by electromagnetically coupling the coupling hole 14.

The input / output capacitors 15 and 16 are arranged in the cavities 9 and 9 of the dielectric resonators 5 and 6, and are composed of a disk-shaped dielectric substrate 17 and both main dielectric substrates 17. It is composed of an inner capacitor electrode (hereinafter, simply referred to as an inner electrode) 18 and an outer capacitor electrode (hereinafter, simply referred to as an outer electrode) 19 formed on the surface. The input / output capacitors 15 and 16 have an inner electrode 18 mechanically and electrically joined to an inner conductor 10 formed on a cavity 9 formed in the opening of the through hole 8 via solder, and are connected to the outside of the capacitor. The electrode 19 is joined to the input / output terminals 20 and 20 via solder.

The input / output terminals 20 and 20 are composed of a lead portion 21 protruding to the outside and a joint portion 22 formed at one end of the lead portion 21. The joint portion 22 has a circular shape having substantially the same diameter as the outer electrode 19. Solder is supplied to the central portion of the joint portion 22, and a hole 23 serving as a joint portion of the solder is formed. The hole 23 has a rectangular shape with one side having a length of about 1 mm, or a circular shape. During the reflow process, the melted solder permeates between the joint 22 and the outer electrodes 19 of the capacitors 15 and 16 through the holes 23, spreads over the entire outer electrodes 19 of the capacitors 15 and 16, and serves as an input / output terminal. Can be integrated.

As shown in FIG. 3, the cases 3 and 4 are flat metal members. The lower case 3 has a substantially rectangular metal plate 25 on which the filter body 2 is placed and joined. Elastic guides 26 and 26 for sandwiching the resonators 5 and 6 are integrally provided on both side edges of the metal plate 25, respectively. Further, ground terminals 27, 27 projecting horizontally from the metal plate 25 are integrally provided on both side edges of the metal plate 25, respectively. Further, on the front side (left side in the figure) of the metal plate 25, claws 28, 28 are integrally provided so as to project in the horizontal direction, respectively, and the tip end portion is bent upward in the figure. A third ground terminal 29 is integrally provided between the claws 28 so as to project in the horizontal direction. A lower connecting piece 30 projecting from the metal plate 25 is integrally provided so as to straddle the ground terminal 29. The lower connecting piece 30 projects horizontally from the metal plate 25, and is bent at a substantially right angle from the mounting portion upward in the drawing.

The upper case 4 is a flat plate-shaped metal member, and as shown in FIG. 3, elastic guides 32, 32 projecting downward from the edge of the metal plate 31 in the drawing are integrally provided. An upper joining piece 33 is provided in front of the metal plate 31 (on the left side in the drawing). The upper joining piece 33 is integrally provided so as to project downward from the front of the metal plate 31. The upper case 4 covers the filter body 2 placed on the lower case 3, and is fixed to the filter body 2 by elastic guides 32, 32. The lower joining piece 30 and the upper joining piece 33 are arranged at positions where they engage with each other.

Further, as shown in FIG. 2, the upper joint piece 33 is pressed toward the front side so as not to come into contact with the input / output terminals 20 and 20 joined to the input / output capacitors 15 and 16 arranged in the cavity 9. The lower connecting piece 30 of the lower case 3 is joined to the upper joining piece 33 of the upper case 4 at a position where it does not contact the input / output terminals 20 and 20.

In the dielectric filter 1, since the lead portions 21, 21 of the input / output terminals 20, 20 extending from the filter body 2 are on the same plane as the lower case 3 having the ground terminals 27, 29, the mounting surface is flat. Is. Therefore, the dielectric filter 1 can be surely surface-mounted on the predetermined circuit board.

Next, a method for manufacturing the above dielectric filter 1 of the present invention will be described.

First, as shown in FIG. 3, the resonators 5 and 6, the input / output capacitors 15 and 16, the input / output terminals 20 and 20, the lower case 3 and the upper case 4 which form the filter body 2 are prepared.

First, cream solder is applied to the surface of the one electrode 17 of the input / output capacitors 15 and 16, and the cream solder is placed in the cavities 9 and 9 of the two resonators 5 and 6 and temporarily held.

Next, cream solder is applied to the metal plate 25 of the lower case 3 and abutted so that the bonding surfaces of the two resonators 5 and 6 are bonded to each other, and the elastic guides 26 and 26 of the lower case 3 are connected to each other. The resonators 5 and 6 are placed on the metal plate 25 so as to be sandwiched between them.

Next, the outer electrodes 19, 19 of the capacitors 15, 16 are connected to the input / output terminals 20, 20 so that the lead portions 21 of the input / output terminals 20, 20 and the ground terminals 27, 29 are flush with each other. The joint portions 22 and 22 are pressed against each other and cream solder is supplied through the holes 23 to temporarily fix the input / output terminals 20 and 20 to the capacitors 15 and 16. Although not shown, the lower case 3 and the input / output terminals 20 and 20 are formed of the same lead frame, and the lead portions 21 of the other input / output terminals 20 and 20 and the ground terminal on the lower case 3 side. The tips of 27 and 29 are flush with each other.

Next, cream solder is applied to the upper surface side of the two resonators 5 and 6, and the upper case 4 is further covered from the upper surface side. Then, cream solder is applied to the engaging surfaces of the upper joining piece 33 and the lower joining piece 30.

Next, the dielectric filter 1 in which the cases 3 and 4 are assembled is passed through a reflow furnace, the cream solder at each joint is melted by heating and soldering is performed, and each solder joint is collectively formed. The solder reflow process makes it possible to achieve a dielectric filter. As a result, the reflow process is performed once, and the cream solder of all the solder joint portions is surely solder-joined, so that easy assembly can be achieved.

In the dielectric filter 1 described above, when cream solder is supplied to the outer electrodes 19 of the input / output capacitors 15 and 16 in order to join the input / output terminals 20 and 20 to the input / output capacitors 15 and 16, Since the cream solder is supplied from the holes 23 of the input / output terminals 20 and 20, the capacitors 15 and 16 do not adhere to the tip of the nozzle of the dispenser, and a predetermined amount of cream solder can be easily and reliably supplied to the predetermined position. You will be able to pay.

When an input / output terminal not formed with the above-described hole 23 is joined to a capacitor as in the conventional case, a predetermined thickness is provided at the interface between the joint of the input / output terminal and the outer electrode of the capacitor. Although it is necessary to interpose a cream solder layer, the molten solder during the reflow process spreads along the leads of the input / output terminals, and does not spread to the electrode surface of the outer electrode of the capacitor, resulting in insufficient soldering strength. However, there is no such lack of strength, and a filter with stable characteristics can be achieved.

FIG. 4 is a partial sectional view showing another embodiment of the present invention.

In this embodiment, a cut-and-raised piece 24 is formed on the outside of the periphery of the hole 23 formed in the joint portion 22 of the input / output terminals 30 and 30, especially on the lower side. The cut-and-raised piece 24 is composed of a bent piece in which one side remaining in the joint 22 is bent at a substantially right angle when the hole 23 is punched in the joint 22.

That is, the input / output terminals 30 and 30 are brought into contact with the outer electrodes 19 of the capacitors 15 and 16, cream solder is supplied to the holes 23, and the cut and raised cuts are made at the time of solder joining by the reflow process. The raised piece 24 holds the cream solder on which it is placed, prevents the cream solder from flowing out, and forms a sufficient solder meniscus, so that a predetermined amount of cream solder can be used for joining without waste.

In order to prevent a short circuit between the outer electrodes 19 of the input / output capacitors 15 and 16 and the inner conductor 10 in the cavity 9 and to further stabilize the characteristics, the input / output capacitors arranged in the cavity 9 are arranged. The outer electrodes 19 of the capacitors 15 and 16 may be projected from the open end faces of the dielectric resonators 5 and 6. By doing this, in the worst case, even if the cream solder supplied to the holes 23 of the input / output terminals 20 and 30 is erroneously supplied and is supplied excessively, the outer electrode 19 of the input / output capacitors 15 and 16 is not supplied. By projecting from the open end faces of the dielectric resonators 5 and 6, the flowed solder does not cause a short circuit in the inner conductor 10 in the cavity 9, and the outer electrodes 19 of the input / output capacitors 15 and 16 are connected to each other. The stray capacitance between the cavity 9 and the inner conductor 10 can be reduced, and stable characteristics can be achieved.

In the manufacturing process described above, cream solder is applied to the joints of the filter body 2, the lower case 3, the upper case 4, the capacitors 15 and 16, and the input / output terminals 20 and 20, and the reflow is performed collectively. Although processed, the capacitors 15 and 16 may be soldered to the resonators 5 and 6 in advance as in the conventional case.

Furthermore, in the above-mentioned configuration, although two resonators are used, a plurality of resonators such as three, four ... May be used, and a single dielectric block may be used. The filter body may have a plurality of through holes and a plurality of resonators formed therein.

[0046]

[Effect of device]

 As described above, in the present invention, since the solder reservoir hole is formed in the input / output terminal joined to the capacitor electrode, the capacitor electrode and the input / output terminal are soldered through the solder reservoir hole. For this reason, it becomes easy to supply solder for joining the capacitor and the input / output terminals, and excessive solder does not enter between the capacitor electrode and the input / output terminals, so that any short circuit with the inner conductor due to solder does not occur. It never happens.

Further, the outer electrode of the capacitor and the input / output terminal are reliably soldered on the entire surface through the solder reservoir hole, so that the mounting strength is increased. In addition, since the cream solder can be supplied from above the input / output terminals, batch processing of reflow solder is possible and assembly is easy.

Further, since the cut-and-raised portion is formed around the solder pool hole toward the outside, the solder arranged in the solder pool hole is held without flowing out. Therefore, the placed solder is used for joining without waste, so that the joining between the two becomes firm and the assemblability is further improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a dielectric filter of the present invention.

FIG. 2 is a schematic cross-sectional view taken along the line I-I of FIG.

FIG. 3 is an exploded perspective view of a dielectric filter.

FIG. 4 is a schematic cross-sectional view of another dielectric filter of the present invention.

[Explanation of symbols]

 1 ... Dielectric filter 2 ... Filter body 3 ... Lower case 4 ... Upper case 5, 6 ... Resonator 9 ... Cavity 10 ... Inner conductor 15, 16 ... ..Input / output capacitors 18 ... Inner electrodes 19 ... Outer electrodes 20, 30 ... Input / output terminals 23 ... Holes 24 ... Cut and raised pieces

Claims (2)

[Scope of utility model registration request] 1. A capacitor is connected between two dielectric resonators forming a filter section and an input / output terminal, one capacitor electrode of the capacitor is connected to an inner conductor of the dielectric resonator, and the other capacitor electrode is A dielectric filter arranged so as to be connected to an input / output terminal, wherein the input / output terminal has a solder pool hole formed at a joint portion to be joined to the capacitor electrode. 2. The dielectric filter according to claim 1, wherein a cut-and-raised portion that bends toward the outside is formed in a lower portion of the solder pool hole of the input / output terminal.