JPH054623U - 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
2, a lid 22 and a sealing material 23 for sealing the opening 4 of the case 2, and the terminal plates 7, 11, 1
3 and a terminal electrode 25 and the like led to the outside. The terminal electrodes 25 and the like are composed of a conductive layer formed on the lid 22.

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 board.

[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 comprises a laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening and containing the laminated body, a lid body for sealing the opening, and a case extending from the terminal plate. And a terminal electrode led to the outside. In this ladder-type filter, the terminal electrode is composed of a conductive layer formed on the lid.

[0006]

[Action]

 In the ladder type filter of the present invention, the terminal electrode can be configured more accurately for surface mounting than when the lead terminal is integrally formed with the terminal plate. Therefore, the ladder-type filter of the present invention is less likely to cause mounting failure during surface mounting.

[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, a substantially L-shaped fixing metal fitting 33 is arranged at the center of the lower corner of the other end of the case 2. The fixture 3 serves as a fixing terminal when surface-mounted on 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, a first parallel resonator 12, It is composed of 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 case 2.

The second series resonator 10, the first parallel resonator 12, and the second parallel resonator 14 are piezoelectric ceramic plate-shaped members having electrodes (not shown) arranged on both main surfaces, 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 two plate members each having a square shape, 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, 14 respectively. The second terminal plate 11 and the third terminal plate 13 respectively have lead portions 18 and 19 extending in the opening 4 direction of the case 2. The two lead parts 18 and 19 are provided so that their positions do not overlap with each other, and extend from one end of the second terminal plate 11 and the central part of the third terminal plate 13 (FIG. 3).

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, a lid 22, 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, 20 project from the corresponding slits of the paper base 21.

As shown in FIG. 4, the lid 22 has a resin main body 24 which is L-shaped in cross section. The main body 24 is arranged outside the paper base 21, and a protrusion 24 a protruding from the opening 4 is formed at one end thereof. The protruding portion 24a has a step portion 24b at the tip. The height l of the step portion 24b is set to be substantially the same as the thickness of each surface of the case 2. On the main surface of the main body 24, the first terminal electrode 25, the second terminal electrode 26, and the third terminal electrode 27 made of a conductive material are known plating methods or thick film forming methods such as coating and hardening of conductive paste such as copper. Is a conductive layer formed in a strip shape. Each terminal electrode 25, 26, 27 has lead portions 25b, 26b, 27b provided with slits 25a, 26a, 27a corresponding to the lead portions 20, 19, 18, respectively. The projecting portion 24a has mounting portions 28a, 29a, 30a integrally extending from the lead portions 25b, 26b, 27b, respectively. Each of the mounting portions 28a, 29a, 30a has a tip portion configured to have substantially the same thickness, and extends to the lower surface of the protruding portion 24a in the figure (FIG. 1).

The lid 22 is inserted into the opening 4 so that the projecting portion 24 a projects from the opening 4. Here, the tips of the corresponding lead portions 20, 19, 18 penetrate through the slits 25a, 26a, 27a of the respective terminal electrodes 25, 26, 27. The lead parts 20, 19, 18 are connected to the lead parts 25b, 26b, 27b by soldering or conductive paste (FIG. 1).

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 terminal electrode 25 and the mounting portion 30a of the third terminal electrode 27 are input / output terminals, and the mounting portion 29a of the second terminal electrode 26 is a ground terminal.

Next, a method of manufacturing the ladder filter 1 will be described. First, the case 2 is prepared, and the members such as the terminal plate and the resonator described above are inserted into the case 2 to arrange the filter member 3. Next, the paper base 21 and the lid 22 having the terminal electrodes 25, 26, 27 are inserted into the opening 4 of the case 2, and the lead portions 20, 19, respectively extending from the terminal plates 7, 13, 11 respectively. Solder to 18. Then, when the opening 4 is further filled with the sealing material 23, the ladder type filter 1 is obtained. In this way, the ladder type filter 1 of the present embodiment can be manufactured only by combining the case 2 with the members such as the lid 22, so that it is more difficult than the case where the lead terminal forming process is required as in the conventional example. Easy automatic assembly by automatic machines.

The ladder type filter 1 is provided for surface mounting so that one main surface of the case 2, that is, the bottom surface, faces 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. At this time, since the mounting portions 28a, 29a, 30a extend to the lower surface of the projecting portion 24a with substantially the same thickness, all of the mounting portions are in good contact with the solder 32. Therefore, the mounting portions 28a, 29a, and 30a are less likely to be defectively mounted.

Since the ladder type filter 1 is the fixing fitting 33, it can be firmly fixed horizontally on the printed wiring board 31.

Second Embodiment In the first embodiment, the lid 22 is composed of the resin main body 24 having the protruding portion 24a, but in this embodiment, as shown in FIG. 7, a flat plate having no protruding portion 24a. The lid 22a in the shape of a circle is used. The lid 22a has a terminal electrode (for example, the terminal electrode 35) extending from the main surface to the lower surface in the drawing. The lower end surface of the lid 22a on which the terminal electrode 35 is formed projects so as to be substantially flush with the lower surface of the case 2 in the drawing. At the lower part of the opening 4 of the case 2 in the drawing, a groove 36 for engaging with the protruding portion of the lid 22a is formed.

Embodiment 3 In this embodiment, the lid 22b is made of a flat plate resin member, and the terminal electrode (for example, the terminal electrode 37) made of a conductive layer is formed on the main surface of the lid 22b. ing. Further, a hole 38 communicating with the terminal electrode is provided on the lower surface of the opening 4 of the case 2 in the drawing. An attachment portion 39 extending to the lower surface of the case 2 in the drawing is formed of a conductive paste in the hole 38, and the attachment portion 39 is integrated with the terminal electrode.

[0024]

[Effect of the device]

 In the present invention, since the terminal electrode is formed of the conductive layer formed on the lid as described above, it is possible to realize a ladder-type filter in which mounting failure is less likely to occur during surface mounting.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment 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 22, 22a, 22b Lid 23 Sealing material 25, 26, 27, 35, 37 terminal electrode

Claims (1)

Claims for utility model registration: Claims: 1. A laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening and accommodating the laminated body, and a lid for sealing the opening. And a surface-mounting ladder type filter including a terminal electrode extending from the terminal plate and led out to the outside, wherein the terminal electrode is formed of a conductive layer formed on the lid body. Type filter.