JPH067320U - Ladder type filter - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the reliability of the ladder type filter with respect to short-circuit or defective joint. [Structure] Inside the case 2 of the ladder type filter 1,
The laminated body in which the resonator and the terminal plate are stacked is accommodated, and the opening 4 of the case 2 is sealed by the lid 22.
The internal terminal plate is joined to the lead terminals 25, 26, 27. The lid 22 includes the joint portions 25a, 26a, 27.
It has rib-like protrusions 41 and 42 arranged between a.

Description

[Detailed description of the device] [Industrial applications]

 The present invention relates to a ladder type filter, and more particularly to a ladder type filter having a laminated body including a piezoelectric resonator and a plurality of terminal plates.

[Prior art]

 As a ladder type filter, a laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening and for housing the laminated body, a lid body for sealing the opening of the case, and a terminal plate There is known one having a lead terminal which is joined to the above and protrudes from the lid (Japanese Patent Application No. 3-69087). The terminal plate and the lead terminal are joined by solder or a conductive adhesive at the joint provided on the lid. In addition, a sealant is filled between the opening of the case and the lid, thereby hermetically sealing the opening. This ladder type filter is mounted on a printed wiring board by lead terminals.

[Problems to be solved by the device]

 In the conventional ladder type filter, when joining the terminal plate and the lead terminal, the joining material composed of a shaving or a conductive adhesive may flow out to short-circuit adjacent lead terminals. In addition, when the opening of the case is filled with the sealing material, the lid already placed in the opening may be tilted. If the sealing material is cured as it is, the lid body and the lead terminals fixed to the lid body are tilted, and as a result, the lead terminals are not properly joined to the board when surface-mounted on the printed wiring board. An object of the present invention is to improve the reliability of a ladder type filter regarding a short circuit or a defective connection.

[Means for Solving the Problems]

 A ladder type filter according to a first aspect of the present invention is a laminated body in which a piezoelectric resonator and a plurality of terminal plates are stacked, a case having an opening and a housing for accommodating the laminated body, and the opening sealed. And a plurality of lead terminals integrally formed with the lid, the base of which is joined to the terminal plate. The lid has a protrusion for preventing short circuit between the joints between the terminal plate and the lead terminal. A ladder type filter according to a second invention is a laminated body in which a piezoelectric resonator and a terminal plate are stacked, an opening having a case for accommodating the laminated body, and a lid body for sealing the opening. And a lead terminal whose base is joined to the terminal plate and which is integrally molded with the lid. The lid has a thick portion for preventing inclination in a portion in contact with the opening.

[Action]

 In the ladder type filter according to the first invention, the lid has the short-circuit preventing protrusion between the joints between the terminal plate and the lead terminal. Therefore, even if the joining material flows out from the joints, the short-circuit preventing protrusions can prevent the joining material from flowing out, and a short-circuit between the joints hardly occurs. In the ladder type filter according to the second aspect of the invention, the lid body has a tilt preventing thick wall portion in a portion adjacent to the opening. Therefore, the lid body disposed in the opening is less likely to tilt, and further, a joint failure due to the tilt of the lead terminal is less likely to occur.

【Example】

 1 to 3 show a ladder type filter as an embodiment of the present invention. In the figure, the ladder type filter 1 mainly has a case 2 and a laminated body 3 housed in the case 2. The case 2 is a hollow and substantially rectangular parallelepiped member made of a heat-resistant resin. An opening 4 is provided at one end of the case 2, and a slight step portion 4a is formed in the opening 4 as shown in FIGS. The laminated body 3 housed in the case 2 includes a U-shaped terminal 9, a second series resonator 10 arranged in the terminal 9, a second terminal plate 11, and a second terminal board in order from the bottom of FIG. The 1 parallel resonator 12, the 3rd terminal board 13, the 2nd parallel resonator 14, and the 1st series resonator 6 on the terminal 9, the 1st terminal board 7, and the spring member 8 are piled up. Is configured. The terminal 9 is composed of a pair of terminal plates 15 and 16 arranged in parallel and a connecting portion 17 connecting the terminal plates 15 and 16 and is formed by bending. The terminal plate 15 is a square plate-shaped member and has a protrusion 5a at the center of the upper surface of FIG. The protrusion 5a is formed, for example, by 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 1 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 plates 15 and 16 and extends parallel to the inner wall surface of the 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, and has a substantially square shape. is there. The thickness of the second series resonator 10 is set to be larger than that of the parallel resonators 12 and 14. The second terminal plate 11 and the third terminal plate 13 are square plate-shaped members (see FIG. 3), 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 lead portions 18 and 19 are provided so that their positions do not overlap each other, and extend from the end portion of the second terminal plate 11 and the central portion of the third terminal plate 13 (FIG. 3). The first series resonator 6 is a piezoelectric ceramic plate-shaped member configured similarly to 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 board 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 of FIG. 2 so as not to approach the lead portions 18 and 19. The spring member 8 is interposed between the upper surface of the case 2 in FIG. 2 and the first terminal plate 7, and is a member for pressing and fixing the laminated body 3 in the case 2 with a constant pressure. The opening 4 of the case 2 in which the laminated body 3 is housed is sealed by a sealing portion including a paper base 21, a lid body 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. The lid 22 has a resin main body 24, as shown in FIG. A first lead terminal 25, a second lead terminal 26, and a third lead terminal 27 are integrally molded in the body 24. Each lead terminal 25, 26, 27 has a fixing portion 25b, 26b, 27b having slits 25a, 26a, 27a corresponding to the lead portions 20, 19, 18, respectively. The fixing portions 25b, 26b and 27b are embedded in the outer surface of the main body 24 opposite to the paper base 21. Each lead terminal 25, 26, 27 has a protrusion 28, 29, 30 protruding from the body 24. The protruding portions 28, 29, 30 project from the same height position of the main body 24 and are inclined downward in the figure, and the tips thereof are bent horizontally to form fixed portions 28a, 29a, 30a. . The fixing portions 28a, 29a, 30a are set flush with the bottom surface of the case 2 or at a height protruding slightly. The lid 22 is inserted into the opening 4 so that the projecting portions 28, 29, 30 project from the case 2. Here, the tip ends of the lead parts 20, 19, 18 from each terminal plate penetrate the slits 25a, 26a, 27a of the corresponding lead terminals 25, 26, 27 and are soldered to the fixing parts 25b, 26b, 27b. It is fixed with a bonding material such as a conductive adhesive (Fig. 2). The bonding material is supplied to the outer main surface side of the main body 24. On the outer main surface of the main body 24, rib-like protrusions 41 extending vertically between the fixing portions 25b and 26b, and rib-like protrusions 42 extending vertically between the fixing portions 26b and 27b are provided. Are integrally formed. These rib-shaped projections 41, 42 are formed between the slits 25a, 26a, 27a to which the bonding material is supplied, and prevent the bonding material flowing out from the slits 25a, 26a, 27a from being blocked by each other. It functions so as not to be short-circuited. The upper and lower end surfaces of the rib-shaped projections 41 and 42 form the same surface as the side surface of the main body 24, and also serve as the upper and lower thick portions of the main body 24. Further, prismatic portions 43 and 44 are integrally formed on both sides of the outer main surface of the main body 24. The side surfaces of the prismatic portions 43 and 44 are flush with the side surface of the main body 24, and are left and right thick portions of the main body 24. The rib-shaped projections 41, 42 and the prismatic portions 43, 44 increase the effective plate thickness of the lid body 24 with the opening 4, that is, the contact area, and the posture of the lid body 22 is stabilized in the opening 4. Therefore, in the manufacturing process, the lid 22 is unlikely to tilt in the opening 4 before the sealing material is filled and before the sealing material is filled and cured. The rib-shaped protrusions 41 and 42 and the prismatic portions 43 and 44 functioning as thick portions are formed in a small portion as compared with the entire area of the outer main surface of the lid body 22. Therefore, a sufficient volume for receiving the sealing material can be ensured in the opening 4, and the lid material made of a high-priced material such as liquid crystal polymer is not unnecessarily increased. The sealing material 23 that covers the lid 22 from the outside is, for example, an epoxy resin, and is filled in the entire opening 4. As a result, the opening 4 is hermetically sealed. An equivalent circuit of the ladder type 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 fixed portion 28a of the first lead terminal 25 and the fixed portion 30a of the third lead terminal 27 are input / output terminals, and the fixed portion 29a of the second lead terminal 26 is a ground terminal. In the ladder type filter, a plurality of piezoelectric resonators and a terminal plate are arranged in the case 2, and then the paper base 21 and the lid 22 are inserted into the opening 4. At this time, since the contact area of the lid 22 with the opening 4 is increased by the thick portion formed by the rib-shaped projections 41, 42 and the prismatic projections 43, 44, the lid 22 is hard to tilt. By maintaining the lid 22 in a normal posture, the fixing portions 28a, 29a, 30a of the lead terminals 26, 27, 28 are maintained in parallel with the bottom surface of the case 2 as a result. In this state, the opening 4 is filled with an epoxy resin serving as the sealing material 23. Next, a bonding material made of solder or conductive resin is supplied to the slits 25a, 26a, 27a from which the lead parts 20, 19, 18 project, respectively, and the lead parts 20, 19, 18 and the lead terminals 26, 27, And 28. Here, even if the joining material flows out from each joining portion, the rib-shaped projections 41 and 42 prevent the joining material from causing a short circuit between the joining portions. The ladder type filter 1 is provided for surface mounting. Here, as shown in FIG. 6, the solder 32 is arranged at a predetermined portion on the printed wiring board 31, and the fixing portions 28a, 29a, 30a are arranged so as to be in contact with the solder 32. At this time, the fixed portions 28a, 29a, 30a reliably contact the solder 32 because the bottom surfaces thereof are substantially parallel to the plane of the case 2 as described above. Therefore, the fixing portions 28a, 29a, 30a are stably fixed to the printed wiring board 31 with the solder 32, and a joint failure between them is unlikely to occur. [Other Embodiments] (a) In the above embodiments, the rib-shaped protrusions extending vertically are provided in order to prevent a short circuit between the joint portion between the lead portion of the terminal plate and the lead terminal, but as shown in FIG. Alternatively, rib-shaped projections 45, 46, 47 surrounding the slits 25a, 26a, 25a may be formed. The rib-shaped protrusions 45, 46, 47 are formed integrally with the main body 24 and prevent short-circuiting in the joint portion. (B) There are many possible variations in the shape and position of the thick portion of the lid that increases the contact area with the case opening. The lid 22 shown in FIG. 8 integrally has a plurality of prismatic protrusions 48 on the four sides of the outer main surface. The lid 22 shown in FIG. 9 has L-shaped protrusions 49 at the four corners of the outer main surface.

[Effect of device]

 In the ladder type filter according to the first aspect of the invention, the lid body has the short-circuit preventing protrusion between the joints of the terminal plate and the lead terminal, so that a short circuit is less likely to occur between the joints. Improves reliability. In the ladder type filter according to the second aspect of the present invention, the lid body has the thick portion for preventing inclination in the portion in contact with the opening, so the lid arranged in the opening is difficult to incline, and therefore the lead terminal is not joined properly. Is less likely to occur and the reliability of the ladder filter is improved.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

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

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

FIG. 4 is a perspective view of a lid and lead terminals.

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

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

FIG. 7 is a view corresponding to FIG. 4 of another embodiment.

FIG. 8 is a view corresponding to FIG. 4 of still another embodiment.

FIG. 9 is a view corresponding to FIG. 4 of still another embodiment.

[Explanation of symbols]

 1 Ladder Type Filter 2 Case 3 Laminated Body 4 Opening 6, 10, 12, 14 Resonator 7, 11, 13, 15, 16 Terminal Plate 23 Sealing Material 25, 26, 27 Lead Terminal 41, 42, 45, 46, 47 Rib-shaped protrusions 43, 44, 48 Prism protrusions 49 Protrusions

Claims (2)

[Scope of utility model registration request] 1. A laminated body in which a piezoelectric resonator and a plurality of terminal plates are stacked, a case having an opening for accommodating the laminated body, and a lid body for sealing the opening. In a ladder type filter provided with a plurality of lead terminals having a base joined to the terminal plate and integrally molded with the lid, the lid prevents short-circuit between a joining portion between the terminal plate and the lead terminal. A ladder-type filter, characterized in that projections for use are formed. 2. A laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening for accommodating the laminated body, a lid body for sealing the opening, and the terminal. In a ladder type filter having a lead terminal joined to a plate and a lead terminal fixedly molded to the lid, the lid has a thick portion for preventing inclination in a portion in contact with the opening. Characteristic ladder type filter.