JPH054624U - Ladder type filter - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a ladder-type filter in which mounting defects are less likely to occur during surface mounting. [Configuration] The ladder type filter 1 includes resonators 6, 10 and 1
2, 14 and terminal plates 7, 11, 13, 15, 16 are stacked, and a filter member group 3 and the filter member group 3
Case 2 for housing the case 2, a sealing material 23 for sealing the opening 4 of the case 2, and a lead terminal 25 connected to the terminal plates 7, 11, 13 and led out from the sealing material 23 to the outside.
And so on. The lead terminals 25 and the like are locked to the surface that becomes the mounting bottom surface of the case 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a ladder type filter, and particularly to a ladder type filter suitable for surface mounting.

[0002]

[Prior Art]

 As a ladder type filter suitable for surface mounting, a laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening and housing the laminated body, a sealing portion for sealing the opening, and a terminal board And a lead terminal that is integrally formed with the lead terminal and protrudes from the sealing portion. In this ladder type filter, the lead terminals are formed outside the encapsulation portion into a shape suitable for surface mounting, and are surface mounted on the printed wiring.

[0003]

[Problems to be solved by the device]

 In the conventional ladder type filter, in order to fully exhibit the electric characteristics of the piezoelectric resonator, the terminal plate forming the laminated body is made of a metal material having a spring property and a small thickness (for example, phosphor bronze). For this reason, it is difficult to accurately form the lead terminal integrally formed with the terminal board for surface mounting. For example, if the forming accuracy of the input, output, and ground lead terminals does not match, when the filter is mounted on the printed wiring board, the lead terminals that are in close contact with the printed wiring board and those that float from the printed wiring board The lead terminals may occur, resulting in defective soldering of the lead terminals.

An object of the present invention is to provide a ladder type filter in which mounting failure is less likely to occur during surface mounting.

[0005]

[Means for Solving the Problems]

 The ladder type filter of the present invention includes a laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening and a case for accommodating the laminated body, a sealing portion for sealing the opening, and a case extending from the terminal plate. In addition, it has a lead terminal led out to the outside. In this ladder type filter, the tip of the lead terminal is locked to the surface which becomes the mounting bottom surface of the case.

[0006]

[Action]

 In the ladder type filter of the present invention, the tip of the lead terminal is locked to the surface which becomes the mounting bottom surface of the case. For this reason, the lead terminals extending from each terminal board have a substantially uniform thickness on the bottom surface of the case with the lead terminals extending from other terminal boards, so there is no variation in processing or deformation due to handling and surface mounting. Installation failure is unlikely to occur.

[0007]

Embodiment 1 FIGS. 1 to 3 show a ladder type filter according to an embodiment of the present invention. In the figure, the ladder type filter 1 mainly has a box-shaped case 2 and a filter member group 3 housed in the case 2.

The case 2 is a hollow, substantially rectangular parallelepiped member made of a resin having a relatively high melting temperature. An opening 4 is formed at one end of the case 2, and a slight step portion 4a is formed in the opening 4 as shown in FIGS. Further, as shown in FIGS. 1 and 2, at the other end of the case 2, an L-shaped fixing metal fitting 33 is provided at the center of the lower corner of the figure. This serves as a dummy terminal for fixing the case 2 to the printed wiring board 31 (see FIG. 6).

The filter member group 3 housed in the case 2 includes a filter unit 5, a first series resonator 6, a first terminal plate 7, and a spring member 8 stacked in order from the bottom of FIG. Is configured.

The filter unit 5 includes a U-shaped terminal 9, a second series resonator 10 stacked in order from the bottom in FIG. 2 in the terminal 9, a second terminal plate 11, and a first parallel resonator. 12, a third terminal plate 13, and a second parallel resonator 14. The U-shaped terminal 9 is composed of a pair of terminal plates 15 and 16 arranged in parallel and a connecting portion 17 connecting both terminal plates 15 and 16. The terminal plate 15 is a square plate-shaped member and has a protrusion 15a at the center of the upper surface of FIG. The projection 15a is formed by, for example, drawing, and is in contact with the second series resonator 10. The terminal plate 16 is formed by stacking two square plate-shaped members, and has protrusions 16a and 16b on both main surfaces. The protrusions 16a and 16b are in contact with the first series resonator 6 and the second parallel resonator 14, respectively. The connecting portion 17 is a member for connecting the terminal plate 15 and the terminal plate 16, and extends parallel to the inner wall surface of the box-shaped case 2.

Each of the second series resonator 10, the first parallel resonator 12, and the second parallel resonator 14 is a piezoelectric ceramic plate-shaped member having electrodes (not shown) arranged on both main surfaces thereof, It has a square shape. The thickness of the second series resonator 10 is set larger than that of the parallel resonators 12 and 14.

The second terminal plate 11 and the third terminal plate 13 are each configured by stacking two square plate-shaped members, and have protrusions 11a, 11b, 13a, 13b on both main surfaces, respectively. . The protrusions 11a, 11b, 13a, 13b are in contact with the opposing resonators 10, 12, 12, 14, respectively. The second terminal plate 11 and the third terminal plate 13 respectively have lead portions 18 and 19 extending in the direction of the opening 4 of the case 2 (see FIG. 3). The lead parts 18 and 19 are provided so that their positions do not overlap with each other, and they extend from one end of the second terminal plate 11 and the central part of the third terminal plate 13, respectively.

The first series resonator 6 is a piezoelectric ceramic plate-shaped member having the same structure as the second series resonator 10. The first terminal plate 7 is a square plate-shaped member and has a protrusion 7a at the center of the lower surface of FIG. The protrusion 7a is in contact with the first series resonator 6. The first terminal plate 7 also has a lead portion 20 extending in the direction of the opening 4. The lead portion 20 is provided at the front end portion in FIG. 2 so as not to overlap the lead portions 18 and 19. The spring member 8 is interposed between the upper surface of the case 2 and the first terminal plate 7, and is a member for pressing and fixing the filter member group 3 in the case 2.

In the filter member group 3, each terminal plate 7, 11, 13, 15, 16 is made of a flexible metal material having a spring property, such as phosphor bronze, and has a thickness of 0.1 mm. It is set to a degree.

The opening 4 of the case 2 in which the filter member 3 is housed is sealed by a paper base 21 and a sealing material 23. The paper base 21 has slits at positions corresponding to the lead portions 18, 19, 20 and is in contact with the step portion 4a. The lead portions 18, 19 and 20 project from the corresponding slits of the paper base 21.

A first lead terminal 25, a second lead terminal 26, and a third lead terminal 27 are soldered to the tips of the lead portions 20, 19, and 18, respectively. As shown in FIG. 4, each of the lead terminals 25, 26, 27 has a slit 25a, 26a, 27a corresponding to the lead portion 20, 19, 18 respectively, a mounting portion 28a, 29a, 30a and a slit 25a ,. It has lead-out parts 28, 29, 30 for connecting 26a, 27a and attachment parts 28a, 29a, 30a. The mounting portions 28a, 29a, 30a are formed in a substantially U shape and have fitting grooves 28b, 29b, 30b, respectively. Each lead terminal 25, 26, 27 has its mounting portion 28a, 29a, 30a elastically fitted and locked by the fitting grooves 28b, 29b, 30b to the lower side of the opening 4 of the case 2 in FIG. reference). The lead portions 20, 19, 18 penetrate through the corresponding slits 25a, 26a, 27a, and are soldered around the slits 25a, 26a, 27a.

The seal material 23 is, for example, an epoxy resin and is filled in the opening 4. Thereby, the opening 4 is hermetically sealed.

An equivalent circuit of the ladder filter 1 is shown in FIG. In the figure, corresponding parts are designated by the same reference numerals. As is apparent from FIG. 5, the mounting portion 28a of the first lead terminal 25 and the mounting portion 30a of the third lead terminal 27 are input / output terminals, and the mounting portion 29a of the second lead terminal 26 is a ground terminal.

The ladder type filter 1 is provided for surface mounting so that one main surface of the case 2, that is, the bottom surface is opposed to the printed wiring board 31. Here, as shown in FIG. 6, the solders 32 and 34 are arranged at predetermined positions on the printed wiring board 31, and the mounting portions 28a, 29a, 30a and the fixing metal fittings 33 are brought into contact with the solders 32 and 34. To place. Here, since the mounting portions 28a, 29a, 30a are along the outer surface of the case 2, all of the mounting portions are in good contact with the solder 32. Therefore, attachment failure is unlikely to occur in the attachment portions 28a, 29a, 30a. The ladder-type filter 1 is horizontally arranged on the printed wiring board 31 by the fixing fitting 33.

Second Embodiment In the first embodiment, the lead portions 20, 19, 18 and the lead terminals 25, 26, 27 are separated from each other as shown in FIG. 2, but they are integrally formed. May be. In this case, for example, the lead terminal 25 is bent so as to be in close contact with the paper base 21 from the state shown by the chain double-dashed line in FIG. Lock. In this embodiment, since the lead portion and the lead terminal are integrally formed, the number of parts is reduced and the manufacturing cost can be reduced.

Third Embodiment In the first and second embodiments, the mounting portion of the lead terminal is fitted in the opening 4, but the present invention is not limited to this. For example, as shown in FIG. 8, a long groove-shaped through hole 22 may be formed in the lower surface of the case 2, and the lead terminal 36 may be inserted from the through hole 22. Here, an L-shaped lead terminal 36 having a mounting portion 35 is used as the lead terminal 36, the lead terminal 36 is connected to a corresponding lead portion in the case 2, and the mounting portion 35 locks the bottom surface of the case 2. And fix it.

[0022]

[Effect of the device]

 In the ladder type filter of the present invention, the tip of the lead terminal is locked to the bottom surface of the case, so that mounting failure is unlikely to occur during surface mounting.

[Brief description of drawings]

FIG. 1 is a perspective view of the first and second embodiments of the present invention.

2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a perspective view of a member adopted in the embodiment.

FIG. 5 is an equivalent circuit diagram of the embodiment.

FIG. 6 is a front view showing a surface mounting state of the embodiment.

FIG. 7 is a diagram corresponding to FIG. 2 of the second embodiment.

FIG. 8 is a diagram corresponding to FIG. 2 of the third embodiment.

[Explanation of symbols]

 1 Ladder type filter 2 Case 3 Filter member group 4 Opening 6, 10, 12, 14 Resonator 7, 11, 13, 15, 16 Terminal plate 23 Seal material 25, 26, 27, 36 Lead terminal 28a, 29a, 30a, 35 Attachment

Claims (1)

Claims for utility model registration: 1. A laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening and containing the laminated body, and a seal for sealing the opening. In a ladder-type filter including a portion and a lead terminal extending from the terminal plate and led out to the outside, a tip of the lead terminal is locked to a surface serving as a mounting bottom surface of the case. Ladder type filter.