JPH0631225U - Ladder type filter - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a small ladder type filter in which the sealing material transmitted to the lead terminals is minimized and the mounting area is further reduced. [Structure] Piezoelectric resonators 6, 8, 10, 11 and terminal plate 5,
A filter member group 3 composed of 7, 9, 12; a case 2 having an opening 4 for accommodating the filter member group 3; a sealing material 23 for sealing the opening 4; and the terminal. Lead terminals 25, 2 extending from the plates 7, 9, 12.
In the ladder-type filter 1 including the reference numerals 6 and 27, the lead terminals 25, 26 and 27 have protrusions 25c, 26c and 27c protruding from the opening 4 of the case 2 and the protrusion 2 respectively.
5c, 26c, 27c fixed portion 25e located below,
It is composed of 26e and 27e.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

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

[0002]

[Prior art]

 Conventionally, as a surface-mounted ladder type filter, a laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening and for accommodating the laminated body, and a case for sealing the opening of the case There is known one provided with a seal material and a lead terminal extending from the terminal plate and protruding from the seal material. In this ladder type filter, the lead terminals are preformed outside the sealing portion into a shape suitable for surface mounting, and the lead terminals are surface mounted on the printed wiring board.

[0006] Specifically, the forming shape of the lead terminal is as follows. The lead terminal extends from the sealing material with which the case opening is filled and extends obliquely from the opening toward the printed wiring board side. The tip of the part extended in the direction away from the case, and was composed of a printed wiring board and a fixing part flush with the bottom surface of the case to enable surface mounting.

[0004]

[Problems to be solved by the device]

 In the conventional ladder type filter, the sealing material that seals the opening of the case is fixed to the lead terminal through the lead terminal due to the inclination angle of the extension of the lead terminal and the viscosity when the sealing material is filled. There is a possibility of reaching the department. When the sealing material reaches the fixing portion of the lead terminal in this way, soldering between the fixing portion of the lead terminal and the printed wiring board becomes impossible.

Further, in the conventional ladder type filter, the fixing portion is formed so as to extend to the outside of the case. Therefore, when the ladder type filter is surface-mounted on the printed wiring board, the area required for mounting is reduced. There was a problem that it would increase.

The present invention has been devised in view of the above problems, and an object thereof is to provide a small ladder type filter in which the influence of the sealing material transmitted to the lead terminals is minimized and the mounting area is further reduced. To do.

[0007]

[Means for Solving the Problems]

 A first invention is 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 sealing material for sealing the opening, In a ladder-type filter including a lead terminal extending from a terminal plate, the lead terminal includes a protruding portion protruding from a sealing material that seals an opening, a bent portion bent downward from the protruding portion, and the bent portion. The ladder-type filter is characterized in that it is composed of a fixed part that is folded back at the same height as the bottom part of the case from the part.

A second invention is a laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening for accommodating the laminated body, and a sealing material for sealing the opening. And a lead terminal extending from the terminal plate, wherein the lead terminal includes a protruding portion protruding from an opening of a case, a bent portion bent downward from the protruding portion at an acute angle, and the bent portion. The ladder-type filter is characterized in that it comprises a fixed part that is bent at the same height as the bottom part of the case from the part.

[0009]

[Action]

 With the above configuration, the protruding portion of the lead terminal protruding from the case opening extends substantially perpendicularly to the seal material, so that the seal material transmitted through the lead terminal can be minimized. As a result, the sealing material does not reach at least the fixed portion of the lead terminal, so that the lead terminal can be stably soldered to the printed wiring board. Moreover, since the filling amount of the sealing material filled in the case opening is not significantly reduced, the case opening can be surely hermetically sealed with the sealing material.

Further, since the fixed portion of the lead terminal is practically provided below the protruding portion, the small ladder type filter reduces the mounting area required on the printed wiring board.

[0011]

【Example】

 Hereinafter, the ladder type filter of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an external perspective view of a ladder type filter of the present invention, and FIG. 2 is a view showing a cross section taken along line II-II in FIG.

The ladder filter 1 mainly has a case 2 and a filter member group 3 housed in the case 2.

The case 2 is a hollow and substantially rectangular parallelepiped member made of a resin having a relatively high melting temperature. 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 FIG.

The filter member group 3 housed in the case 2 includes, in order from the bottom of FIG. 2, a U-shaped terminal plate 5 that also serves as the first and fourth terminal plates, a first series resonator 6, and a first series resonator 6. A second terminal plate 7, a second parallel resonator 8, a third terminal plate 9, a second parallel resonator 10 and a U-shaped terminal plate 5 serving as a fourth terminal plate. The two-series resonator 11 and the fifth terminal 12 are laminated and configured. When housed in the case 2, the spring terminals 13 for stably connecting the terminal plates 5, 7, 9, 12 of the filter member group 3 and the resonators 6, 8, 10, 11 are provided. Further stacked.

In addition, on the main surface of each of the terminal plates 5, 7, 9 and 12, protrusions 5 a, 7 a, 9 a and 12 a are formed at the connecting portions with the resonators 6, 8, 10 and 11, respectively. .

Further, the second terminal plate 7, the third terminal plate 9, and the fifth terminal plate 12 are formed with lead portions 7 b, 9 b, 12 b extending to the opening 4 of the case 2. The lead portions 7b, 9b, 12b are arranged and extended so as not to overlap each other when viewed from the top of the ladder type filter.

The resonators 6, 8, 10 and 11 are made of a piezoelectric ceramic plate-shaped member having electrodes (not shown) formed on both principal surfaces thereof, and have a substantially square shape. The thicknesses of the first and second series resonators 6 and 11 are set to be larger than those of the first and second parallel resonators 8 and 10.

The opening 4 of the case 2 in which the above-mentioned filter member group 3 is housed is hermetically sealed by a sealing portion including 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 7b, 9b, 12b of the second terminal plate 7, the third terminal plate 9, and the fifth terminal plate 12, and is in contact with the step portion 4a. There is. The lead portions 7b, 9b, 12b project outward from the corresponding slits in the paper base.

As shown in FIG. 3, the lid 22 has a resin main body. The main body 24 is arranged outside the paper base 21. The main body 24 is integrally molded with a first lead terminal 25 connected to the lead portion 7b, a second lead terminal 26 connected to the lead portion 9b, and a third lead terminal 27 connected to the lead portion 12b. Each lead terminal 25, 26, 27 has a fixing portion 25b, 26b, 27 having a slit 25a, 26a, 27a corresponding to the lead portion 7b, 9b, 12b, respectively, and is embedded in the main body 24. Has been done. Each of the lead terminals 25, 26, 27b includes a protruding portion 25c, 26c, 27c protruding substantially vertically from the main body 24 and bent portions 25d, 26d, 27d bent downward at the tips of the protruding portions 25c, 26c, 27c. And the fixing portions 25e, 26e, 27e extending horizontally from the bent portions 25d, 26d, 27d toward the case side, which is bent at the same height as the bottom surface of the case 2.

The lid 22 is inserted into the opening 4 so that the projecting portions 25 c, 26 c, 27 c project from the case 2, and is placed on the paper base 21. Then, the tips of the lead portions 7b, 9b, 12b of the respective terminal plates 7, 9, 12 penetrate the slits 25a, 26a, 27a of the corresponding first, second and third lead terminals 25, 26, 27. The lead portions 7b, 9b, 12b and the lead terminals 25, 26, 27 are soldered, mechanically joined by a conductive adhesive, and electrically connected.

The sealing material 23 is, for example, a thermosetting resin such as an epoxy resin, and is filled in the concave portion formed by the opening 4 of the case 2 and the lid 22. As a result, the opening 4 is hermetically sealed.

The ladder filter having the above structure has an equivalent circuit shown in FIG. In the figure, corresponding parts are designated by the same reference numerals. As is apparent from FIG. 4, the fixed portion 25e of the first lead terminal 25 and the fixed portion 27e of the third lead terminal 27 serve as input / output terminals, and the fixed portion 26e of the second lead terminal 26 serves as a ground terminal.

A feature of the present invention is that the lead terminals 25, 26, and 27, which are led out from the filter member group 3 for connecting to an external circuit, protrude from the sealing material 23 substantially vertically. 25c, 26c, 27c and bent portions 25d, 26d, 27d bent downward at the tips of the protrusions 25c, 26c, 27c and the tips of the bent portions 25d, 26d, 27d are bent to the case 2 side and the case 2 is composed of fixing portions 25e, 26e and 27e having substantially the same height as the bottom surface. That is, the lead terminals 25, 26, 27 project once outwardly of the case 2 and are folded back to form a U shape in a side view, and the fixing portions 25e, 26e, 27e are substantially formed. The protrusions 25c, 26c, and 27c are located below the protrusions. The length of the projecting portions 25c, 26c, 27c projecting substantially vertically from the opening 4 of the case 2 is set to be 1 to 1.5 mm from the sealing material 23.

By using the lead terminals 25, 26, 27 having such a structure, the main body 24 of the lid 2 is arranged in the opening 4 of the case 2, and the lead portion 7 b extending from the terminal plates 7, 9, 12 is formed. , 9b, 12b and the lead terminals 25, 26, 27 are mechanically joined and electrically connected, and when the sealing material 23 is filled, the lead terminals 25, Even when trying to crawl on 26 and 27, since the protrusions 25c, 26c and 27c are substantially perpendicular to the sealing material 23, the amount of creeping up is extremely small. In addition, since the length thereof is 1 to 1.5 mm, which is a sufficient length, even if the creeping phenomenon is significantly generated due to the viscosity of the sealing material 23, the bending portions 25d, 26d, and 27d have Never reach. Therefore, of course, the sealing material 23 never reaches the fixing portions 25e, 26e, 27e of the lead terminals 25, 26, 27, so that the solder joint between the printed wiring board and the fixing portions 25e, 26e, 27e is performed. In this case, this solder joint is not obstructed at all.

Further, since the fixed portions 25e, 26e, 27e of the lead terminals 25, 26, 27 are folded back toward the case 2 at the tips of the bent portions 25d, 26d, 27d, the fixed portions 25e, 26e, Since 27e is arranged below the protrusions 25c, 26c, and 27c, the mounting area on the printed wiring board is smaller than that of the ladder type filter that is conventionally bent outside the case 2, and the printed wiring board is reduced. Highly dense electronic circuits can be constructed on the substrate.

FIG. 5 is a side view showing a second device of the ladder type filter of the present invention.

According to the second invention, the lead terminal extending from the opening of the case 2 (only one lead terminal 28 appears in FIG. 5) is a protrusion protruding substantially perpendicular to the sealing material 23. The portion 28c, the bent portion 28f in which the angle formed by the protruding portion 28c and the protruding portion 28c is bent at an acute angle, and the tip of the bent portion 28f is substantially level with the bottom surface of the case 2 in the direction away from the case 2. And a fixed portion 28g bent at a length.

Therefore, since the projecting portion 28c projects substantially perpendicularly to the sealing material 23, the creeping-up of the sealing material 23 can be minimized as described above. Also, in the structure of the second invention, since the fixing portion 28g is arranged below the projecting portion 28c, the small ladder type filter has a small mounting area on the printed wiring board.

In the above-mentioned embodiment, the description has been given of the 4-element ladder type filter using the two series resonators and the two parallel resonators, but the number of the elements is not limited to four. The number of elements can be arbitrarily changed according to the filter characteristics.

Further, the case 2 has the opening 4 provided only on one end side, and the lead terminals 25, 26, 27, 28 are led out from this opening, but firmly joined to the other end side of the case 2 during surface mounting. The dummy terminal for fixing may be integrally molded so as to perform.

Further, openings may be provided at both ends of the case 2, and the lead terminals led out from the filter member group 3 may be led out from the openings. Also in this case, it is important that the projection portion, the bending portion, and the fixing portion that is folded back to the case 2 side be used.

[0033]

[Effect of device]

 As described above, in the ladder type filter according to the present invention, the lead terminal projects from the sealing material substantially perpendicularly, the bent part bent downward from the projected part, and the bent part to the case. Or a projecting part in which the lead terminal projects substantially perpendicular to the sealing material, a bent part bent downward from the projecting part at an acute angle, and the bent part. Since it consists of a fixed part that is folded back from the case to the outside of the case, the amount of sealing material that creeps up to the protruding part of the lead terminal can be minimized, so the filling amount of sealing material is insufficient and sealing failure occurs. Does not occur, and at the same time, when the fixing portion and the printed wiring board are joined together, the sealing material is not present, so that strong solder joining can be performed.

Further, since the fixed portion of the lead terminal is substantially present below the protruding portion, the required mounting area can be reduced when the surface mounting is performed on the printed wiring board.

[Brief description of drawings]

FIG. 1 is an external perspective view of a ladder type filter of the present invention.

FIG. 2 is a vertical sectional view showing a section taken along line II-II in FIG.

FIG. 3 is an external perspective view of a lid body.

FIG. 4 is an equivalent circuit diagram of the ladder filter of the present invention.

FIG. 5 is a side view of another ladder type filter of the present invention.

[Explanation of symbols]

 1 ... Ladder type filter 2 ... Case 3 ... Fill member group 5, 7, 9, 12 ... Terminal plate 6, 11 ... Series resonator 8, 10 ... Parallel Resonator 4 ... Aperture 13 ... Spring terminal 23 ... Sealing material 25, 26, 27, 28 ... Lead terminal 25c, 26c, 27c, 28c ... Projection portion 25d, 26d, 27d, 28f. ..Bent parts 25e, 26e, 27e, 28g

Claims (2)

[Scope of utility model registration request] 1. 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 sealing material for sealing the opening, and the terminal. In a ladder-type filter including a lead terminal extending from a plate, the lead terminal includes a protruding portion protruding from an opening of a case, a bent portion bent downward from the protruding portion, and an inside of the case from the bent portion. A ladder-type filter comprising a bottom surface of a case and a fixed portion folded back to the same height. 2. A laminated body in which a piezoelectric resonator and a terminal plate are stacked, a case having an opening for housing the laminated body, a sealing material for sealing the opening, and the terminal. In a ladder-type filter including a lead terminal extending from a plate, the lead terminal includes a protruding portion protruding from an opening of the case, and a bent portion bent downward from the protruding portion at an acute angle,
A ladder-type filter comprising: a bent portion and a fixing portion that is bent at the same height as the bottom surface of the case.