JPH07193460A - Ladder filter - Google Patents

Abstract

PURPOSE:To improve bonding strength of solder by distributing lead terminals to the counter terminal parts of a case and bending them to form a solder fillet. CONSTITUTION:A first lead terminal 41 is embedded at a thick part on the bottom of a case 3, and its one end forms an exposed part 41a inside one opening part of the case 3. Further, the other end is exposed on the bottom of the counter opening part of the case 3, and a bonding part 41b is formed at one part of a side face orthogonal with the bottom of the case 3 by bending the top end. On the other hand, one end of second lead terminals 42 and 43 is exposed around through holes 54a and 54c and protruded from a prescribed position on the opening outside of a main body 51 to the outside. Then, extended parts 42a and 43a, solder fillet forming parts 42b and 43b vertically bent downward from here and wiring board bonding parts 42c and 43c are formed. The bonding parts 42c and 43c are bent so as to be arranged at the depressed parts of the case 3, and its cross-section is U-shaped as a whole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ladder type filter, and more particularly to a surface mount type ladder type filter.

[0002]

2. Description of the Related Art Conventionally, as a surface-mounted ladder type filter, a part of a terminal plate of a laminated body composed of a piezoelectric resonator and a terminal plate housed in a case is used as a lead terminal and extends outside the case. Specifically, using a normal ladder type filter, specifically, the lead terminals extending to the outside of the case were bent so that the tips of the lead terminals were substantially parallel to the bottom surface of the case (bonding surface of the wiring board) ( Actual Kaihei 2-32322).

In such a surface-mounted ladder type filter, in order to bend the lead terminal extending outside the case by using a bending jig or the like, the bent portion of the lead terminal and the case are It was necessary to provide a sufficient space between them. For this reason, when the surface-mounting ladder type filter is surface-mounted on the printed wiring board, there is a problem that the area occupied by the bonding becomes very large. Further, there is a problem in that the bending treatment state is deformed between the plurality of lead terminals by the control of the bending jig, and it is difficult to obtain the lead terminals that are uniformly bonded to the printed wiring board.

This occurs because the lead terminal, which is a part of the terminal plate extending from the case, is simply subjected to a bending treatment by using an ordinary lead-bonding ladder type filter so as to correspond to the surface mounting type. Is.

Therefore, the present inventor has proposed a ladder type filter having a terminal plate and a lead terminal as separate members as a structure suitable for a surface mount type ladder type filter. Also,
We proposed a ladder-type filter in which the terminal plate, the lead terminal, and the intermediate conductor connecting both of them were composed of separate members.

A ladder type filter in which the terminal plate and the lead terminal are separate members is, for example, Japanese Utility Model Laid-Open No. 5-4622, in which all of the lead terminals are integrally formed on the lid body. A part of the plate is connected to the lead terminal near the lid. According to this, since the bending processing of the plurality of lead terminals can be performed by the processing on the lid side, it can be performed easily and accurately, and as a result, the joint surface of the plurality of lead terminals can be formed on the printed wiring board. Each can be reliably joined.

Further, the latter type of ladder type filter in which the terminal plate, the lead terminal, and the intermediate conductor are separate members is, for example, Japanese Patent Application No. 5-22691, in which all the lead terminals are arranged in the case opening. It is integrally molded by mode molding so as to be exposed on the bottom surface side, and the lid body is integrally formed with an intermediate conductor that connects a part of the terminal plate and the lead terminal integrated with the case. In particular, in order to ensure the bonding stability when mounted on the surface, one of the plurality of lead terminals is routed to the end portion on the side facing the opening, using the bottom surface of the case.

[0008]

However, the actual Kaihei 5-4
In the surface-mounting ladder type filter 622, the bending of the lead terminals is led out from the opening obliquely outward, and therefore, when surface-mounted on the printed wiring board, the effect of reducing the occupied area is sufficiently obtained. I can't. In addition, when reflow soldering is performed, only one end side of the opening side is joined, so the joining stability is poor, and the solder rise (solder frets) is not sufficiently formed, resulting in sufficient joining. There was a problem that strength could not be obtained.

Further, in the surface-mounted ladder type filter of Japanese Patent Application No. 5-22691, since the lead terminals are formed integrally with the case, there is a sufficient amount of solder frets especially at the lead terminals on the case opening side. However, there is a problem in that it cannot be formed. This is because it is regulated by the thick part of the case around the opening.

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to sufficiently form a solder fret and to minimize the area occupied by surface mounting, and further to mount the surface. The present invention provides a ladder type filter having excellent joint stability.

[0011]

According to the present invention, there is provided a laminated body of a piezoelectric resonator and a terminal plate, a hollow portion for accommodating the laminated body, and an opening at one end portion thereof. A case integrally formed so that a first lead terminal connected to the first end extends to the other end side facing the opening side; and the terminal plate and the first lead terminal fitted into the opening. A ladder-type filter comprising: an intermediate conductor for joining and a lid body integrally formed with a second lead terminal connected to the terminal plate, wherein the second lead terminal comprises:
A schematic cross-section consisting of an extending portion projecting outward of the opening, a solder fret forming portion bent downward from the extending portion substantially vertically, and a wiring board joint portion bent from the solder fret forming portion to the case side. It is a ladder type filter characterized by being U-shaped.

[0012]

According to the present invention, when the first lead terminal and the second lead terminal are distributed and led out to the opposite ends of the case, they are mounted on the printed wiring board by surface mounting. , Its bonding stability is improved.

Further, since the second lead terminal has the extending portion projecting outward of the opening and the solder fret forming portion bent downward from the extending portion and substantially vertically, the printed wiring board is formed. When surface-mounted, the solder frets of the reflowed solder can be sufficiently formed, so that a strong joint can be achieved.

Moreover, since the tip end of the second lead terminal, that is, the wiring board joint portion is bent to the case side and has a substantially U-shaped cross section as a whole, the mounting exclusive area on the printed wiring board is minimized. Can be converted.

Structurally, the piezoelectric resonator, the terminal plate and the first lead terminal are integrated with each other, and the case body has an opening, the second lead terminal connected to the terminal plate, the terminal plate and the first lead terminal.
Since it is composed of the lid body integrally formed with the intermediate conductor for connecting to the lead terminal, the number of parts thereof does not increase, and therefore the productivity is not deteriorated at all.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The ladder type filter of the present invention will be described below 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 XX in FIG. In addition, in the embodiment, a four-element type including two series resonators and two parallel resonators will be described.

The ladder type filter 1 comprises a piezoelectric resonator 11,
A case 3 in which a filter member group including 12, 13, 14 and terminal plates 21, 22, 23, 24 and a first lead terminal 41 are integrated, second lead terminals 42, 43, an intermediate conductor 4
It is mainly composed of a lid body 5 in which 4 is integrated.

As shown in FIG. 3, the case 3 is made of a resin having a relatively high melting temperature, for example, a liquid crystal polymer, and has a substantially rectangular parallelepiped shape having a housing hollow portion inside. An opening 31 is provided at one end of the case 3, and a slight step 32 is formed in the opening 31 as shown in FIG. The step portion 32 acts on the positioning of the lid body 5.

Further, recesses 33 and 34 are formed on the bottom surface of the end of the case 3 on the side of the opening 31. This dent 3
Nos. 3 and 34 are the ones in which the tips of the second lead terminals 42 and 43 are arranged, and prevent the height of the ladder type filter from increasing due to the thickness of the second lead terminals 42 and 43. This is for temporarily holding the lid body 5 in which the lead terminals 42 and 43 are integrated.

The case 3 has a first lead terminal 4 surface-mounted on a predetermined wiring pattern of a printed wiring board.
1 is integrally formed.

The first lead terminal 41 is made of, for example, iron plated with a metal having good solder wettability such as Ag, and is embedded in the thick portion of the bottom surface of the case 3, one end of which is The case 3 is exposed inside the one end side where the opening 31 is formed, the other end is exposed at the bottom surface of the other end of the case 3 facing the opening 31 as shown in FIG. 2, and the tip of the other end is It is bent and arranged on a part of a side surface orthogonal to the bottom surface of the case 3. The opening 31 of the case 3
The one end portion exposed to the side is particularly referred to as an exposed portion 41a of the first lead terminal, and the other exposed end portion of the bottom surface and the side surface is particularly referred to as a joint portion 41b of the first lead terminal 41.

The structure of the case 3 and the first lead terminal 41 can be integrally formed by resin molding.

A filter member group is laminated in the case 3 described above. Specifically, as shown in FIG. 2, from the bottom, a U-shaped terminal plate 2 that also serves as the first and fourth terminal plates 2
1 part, the first series resonator 11, the second terminal plate 22, the second
Parallel resonator 12, third terminal plate 23, and second parallel resonator 1
3, a part of the U-shaped terminal plate 21 which becomes the fourth terminal plate, the second
The series resonator 14 and the fifth terminal 24 are sequentially stacked. Actually, when the case 3 is housed in the case 3, the first series resonator 11 and the second series resonator 11 are placed in the U-shaped terminal plate 21.
A terminal plate 22, a second parallel resonator 12, a third terminal plate 23,
The second parallel resonator 13 is arranged, the second series resonator 14 and the fifth terminal 24 are stacked on the U-shaped terminal plate 21, and the filter member group is provided in the upper gap inside the case 3. The spring terminals 25 for stably connecting the respective terminal plates 21 to 24 and the piezoelectric resonators 11 to 14 are further laminated.

Each of the terminal plates 21 to 24 is made of a metal having a spring property, such as phosphor bronze, and is formed into a single plate shape, a folded laminated plate shape, a U-shaped cross section, or the like.

On the main surfaces of the terminal plates 21 to 24, which are electrically connected to the resonators 11 to 14, the protrusions 21 are respectively provided.
a to 24a are formed by press molding or the like.

The second terminal plate 22, the third terminal plate 23, and the fifth terminal plate 24 are provided with lead portions 22b, 23b, 24b extending horizontally from the main surface to the opening 31 of the case 3. There is. The lead portions 22b, 23b, 24b are
When viewed from the top of the ladder type filter, they are displaced so as not to overlap each other and extend into the opening 31 of the case 3.

The piezoelectric resonators 11 to 14 have electrodes (
(Not shown) is formed of a piezoelectric ceramic plate-shaped member and has a substantially square shape. First and second series resonator 1
The thicknesses of 1 and 14 are set to be larger than those of the first and second parallel resonators 12 and 13.

As shown in FIG. 4, the lid 5 is made of, for example, a resin such as liquid crystal polymer, and has a main body 51 and a main body 51.
Ribs 52, 53 that divide the outer main surface of the
Second lead terminals 42, 43 integrated with the main body 51,
And an intermediate conductor 44.

In the main body 51, in each region where the outer main surface is partitioned into three regions by the ribs 52 and 53, the second
Through holes 54a, 54b, 54c through which the lead portions 22b, 23b, 24b of the terminal plate 22, the third terminal plate 23, and the fifth terminal plate 24 respectively extend. At least one ends of the second lead terminals 42, 43 and the intermediate conductor 44 integrated with the main body 51 are exposed around the through holes 54a, 54b, 54c.

Second lead terminal 4 embedded in main body 51
2, 43 and the intermediate conductor 44 are made of, for example, iron plated with a material having a good solder wetting property such as silver.

One end of each of the second lead terminals 42 and 43 is exposed at least around the through holes 54a and 54c, and the second lead terminals 42 and 43 extend outward from a predetermined position on the outer surface of the opening of the main body 51. It is protruding. Then, the second lead terminals 42, 43 projecting outward of the opening of the main body 51 have the extending portions 42a, 43a projecting outward of the opening, the extending portion 42a,
43a, solder fret forming portions 42b, 43b bent downward substantially vertically, and the solder fret forming portions 42b, 43
The wiring board joint portions 42c and 43c are bent so as to be arranged in the recesses 33 and 34 of the case 3 from b to the case 3 side, and have a generally U-shaped cross section.

Here, the extension amount of the extension portions 42a, 43a of the second lead terminals 42, 43 is determined by the lead terminals 42, 43.
Is set to a length that extends at least outward from the opening 31 of the case 3, and is vertical or inclined with respect to the main body 51.

Further, the solder fret forming portions 42b and 43b of the second lead terminals 42 and 43 are set to be substantially vertical on the printed wiring board, and their length (distance in the height direction) is the surface. For example, 1.5 m so that the solder rise (solder frets) can be formed when mounted.
It is more than m.

Further, the wiring board joint portions 42c and 43c of the second lead terminals 42 and 43 substantially contact the predetermined wiring pattern of the printed wiring board from the solder fret forming portions 42b and 43b to the case 3 side. Is formed by bending treatment so that a part of the tip is formed on the bottom surface of the opening 31 portion of the case 3 with the recessed portions 33, 34.
It has a length that can be placed at.

One end of the intermediate conductor 44 is exposed at least around the through hole 54b, and the other end is vertically and downwardly extended and is exposed. still,
The exposed portion at the other end is referred to as a lead terminal connecting portion 44a.

The above-mentioned piezoelectric resonators 11 to 14 and the terminal plate 21.
To 24, the case 3, and the lid body 5 will be briefly described. First, in the case 3, the piezoelectric resonators 11 to 14 and the filter plates including the terminal plates 21 to 24 and the spring terminal 2 will be described.
5 are stacked and arranged in a predetermined order.

Next, a through hole 54 is formed in the opening 31 of the case 3.
A base thin plate 61 made of paper or film having holes or notches formed at positions corresponding to a, 54b, and 54c is fitted and arranged. This allows the terminal board 22 to be removed from the holes or notches.
-24 lead parts 22b-24b are inserted. The positioning of the base thin plate 61 is performed by the step portion 32 provided around the inner wall of the opening 31 of the case 3.

Next, the lid 5 in which the second lead terminals 42 and 43 and the intermediate conductor 44 are integrated is fitted into the opening 31 of the case 3. At this time, the lead portion 22b of the terminal plate 22 in which the base thin plate 61 is inserted protrudes from the through hole 54a of the lid 5, and the lead portion 23b of the terminal plate 23 in which the base thin plate 61 is inserted protrudes from the through hole 54b. The lead portion 24b of the terminal plate 24 in which the thin base plate 61 is inserted through the hole 54c.
Protrudes. The positioning of the lid 5 is performed through the base thin plate 61 at the step portion 32 provided around the inner wall of the opening 31 of the case 3.

As a result, the second lead terminals 42, 43 having a generally U-shaped cross section projecting from the lid 5 project outside the opening 31, and the tips thereof are recessed portions 33 on the bottom surface of the case 3. Will be placed at 34.

The lead terminal connecting portion 44a at the lower end of the intermediate conductor 44 embedded in the lid 5 and the exposed portion 41a at one end of the first lead terminal 41 exposed from the inner wall of the bottom surface of the opening 31 of the case 3 are close to each other. It will be in the state of doing.

Next, one end of the intermediate conductor 44 of the second lead terminals 42 and 43 exposed around the through holes 54a to 54c and the terminal plate 2 protruding from the through holes 54a to 54c.
The lead portions 22b to 24b of 2 to 24 are electrically connected to the tip portions of the lead portions 22b to 24b by connecting members 62 ... Of solder or conductive resin. Here, the rib 5 of the main body 51 of the lid 5
2 and 53 are formed, the joint between one end of each second lead terminal 42 and the lead portion 22b, the joint between one end of the second lead terminal 43 and the lead portion 24b, and the intermediate conductor 44. Since the one end and the joint portion of the lead portion 23b are divided into respective regions, the connecting members 62 ... Do not short-circuit to the adjacent connecting portions.

At the same time, the lead terminal connection portion 44a of the intermediate conductor 44 and the exposed portion 41a of the first lead terminal 41 are formed.
Are electrically connected by the connecting member 63.

At this time, the main body 51 of the lid 5 is the ridge rib 5
Since 2, 53 are formed, the inner wall of the case 3 and the end faces of the ribs 52, 53 come into contact with each other over a relatively wide area, so that the lid 5 fitted in the opening 31 is displaced. It can be temporarily held stably.

As a result, the second terminal plate 22 is electrically connected to the second lead terminal 42 through the lead portion 22b, and the third terminal plate 23 includes the lead portion 23b and the intermediate conductor 44. The fifth terminal board 24 is electrically connected to the first lead terminal 41 through the lead portion 24b, and the second terminal 43 is electrically connected to the second lead terminal 43 through the lead portion 24b.

Next, the space region sandwiched between the lid 5 and the opening 31 of the case 3 is filled with a sealing material 64 made of a thermosetting resin such as an epoxy resin, and thermoset.

When the sealing material 64 such as resin is filled and cured, the lid 5 is already attached to the conductive connecting members 62, 63.
Since it is held by, for example, the filling can be performed very stably, and the inside of the case 3 can be hermetically sealed with high reliability.

As a result, a filter in which the first series resonator 11, the parallel resonator 12, the second parallel resonator 13 and the second series resonator 14 are connected in a ladder type is achieved.

The above-mentioned ladder type filter is surface-mounted by a reflow soldering process on a predetermined wiring pattern of a printed wiring board (not shown).

In surface mounting by reflow soldering, cream-like solder is generally applied on a predetermined wiring pattern of a printed wiring board (not shown), and the wiring pattern and the surface-mounting ladder type filter 1 applied with the cream-like solder. Of the lead terminals 41, 42, and 43 are brought into contact with each other, and then, together with other surface-mounted electronic components, 20
The cream solder is melted by being placed in a reflow oven at about 0 ° C. and cooled, and the solder is cooled and hardened.

The solder melted by the reflow process spreads due to the solder wettability of the lead terminals 41 to 43. At this time, since the tip of the first lead terminal 41 is bent, the melted solder rises to a part bent at a substantially right angle to the printed wiring board, and the second lead terminal 42 is also bent. , 43, the solder rises to a part of the solder fret forming portions 42b, 43b, which is a middle portion, so that a strong mechanical joint and a reliable electric joint can be achieved with a predetermined wiring pattern of the printed wiring board.

At this time, especially the second lead terminals 42, 43
In the above structure, it is desired to minimize the area occupied by surface mounting on the printed wiring board. In the present invention, in the second lead terminals 42 and 43, the area outside the opening 31 of the case 3 is provided. The extending portions 42a and 43a protruding in one direction
Of the solder fret forming portion 42
The portions b and 43b are prevented from significantly protruding to the outside of the case 3, and the wiring board joint portion 42c,
Since 43c is bent to the case 3 side, the maximum portion protruding outward of the case 3 is the solder fret forming portion 4
Since it is 2b and 43b, it is possible to minimize the occupied area as a whole.

Here, the distance between the opening 31 of the case 3 and the solder fret forming portions 42b and 4ba is zero (the periphery of the opening 31 of the case 3 and the second lead terminals 42 and 43 are brought into contact with each other). desirable. In this case, the seal member 6
When the resin to be No. 4 is filled, the resin may spread to the second lead terminals 42 and 43 due to the surface tension of the resin. Therefore, it is important to control the viscosity of the resin to a predetermined level. .

Even if the resin spreads on the lead terminals 42 and 43, since the main surface to which the solder for soldering on the printed wiring board adheres is different from the main surface on which the resin spreads, it is different from the printed wiring board. There is no possibility that solder joints with the lead terminals 42 and 43 cannot be performed, and the reliability of electrical connection and mechanical joint is not lowered. On the contrary, when the resin of the sealing material 64 spreads to the tip portions of the second lead terminals 42 and 43, the recesses 33 and 3 formed on the bottom surface of the case 3 are formed.
4 may reach the gap between the lead terminals 42 and 43 and strengthen the mechanical fixing between the lead terminals 42 and 43 and the case 3.

Further, as described above, the wiring board joint portion 42 is formed.
c and 43c are bent toward the case 3, and the solder frets in the solder fret forming portions 42b and 43b are
Solder fret forming portions 42b, 43b on the outer side of the case 3
Since it is formed on the main surface of the solder fret, the solder fret can be visually neglected in appearance, and the state of formation of the solder fret, that is, the state of connection between the printed wiring board and the surface-mounted ladder type filter 1 can be easily judged by visual observation. can do.

Further, although the lead portions 22b, 23b, 24b of the second terminal plate 22, the third terminal plate 23, and the fifth terminal plate 24 of the filter constituent member extend to the opening 31 side, in particular, The lead portion 23 b is connected to the first lead terminal 41 via the intermediate conductor 44 integrated with the main body 51 of the lid body 5.
The joint portion 41b of No. 3 extends to the end of the case 3 on the side facing the opening 31. That is, the second lead terminals 42, 43 are arranged at the ends of the case 3 on the side of the opening 31 and the first lead terminals 41 are separately arranged at the ends facing the openings 31, so that the second lead terminals 42, 43 are arranged on the printed wiring board. In the case of solder joining, the joining stability of the surface mount ladder type filter is improved.

Further, among the entire lead terminals (three lead terminals in the embodiment), the thickness is distributed to the opening 31 side of the case 3 and the side opposite to the opening 31 by utilizing the thickness portion of the bottom surface of the case 3. For example, the distance between the second lead terminals 42 and 43 arranged on the side of the opening 31 is made wider than the distance between the lead terminals 42 and 43 as compared with the case where three lead terminals are usually drawn from the opening. Can be done easily.
As a result, when soldered to the printed wiring board,
It is possible to eliminate the short circuit phenomenon due to the generation of the solder bridge between the lead terminals. Further, even when the number of lead terminals is increased, it is possible to easily cope with it, and conversely, it is possible to easily cope with a small ladder type filter.

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

[0059]

As described above, since the lead terminals are respectively distributed to the opposite ends of the case and the bending processing is performed so that the solder frets can be formed, the solder frets improve the solder joint strength. . Also, the bonding stability of surface mounting is very excellent.

Since the second lead terminal arranged on the opening side of the case is bent to have a substantially U-shaped cross section, the area occupied by the surface mounting can be minimized.

[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 XX in FIG.

FIG. 3 is an external perspective view of a case.

FIG. 4 is an external perspective view of a lid body.

[Explanation of symbols]

 1 ... Ladder type filter 11-14 ... Piezoelectric resonator 21-24 ... Terminal plate 3 ... Case 31 ... Opening 41 ... First lead terminal 42, 43 ... Second lead terminal 41b ... Joint portion 42b, 43b ... Solder fret forming portion 44 ... Intermediate conductor 5 ... Lid body 64 ... Seal material

Claims (1)

[Claims] 1. A first lead terminal having a laminated body of a piezoelectric resonator and a terminal plate, a hollow portion for accommodating the laminated body, having an opening at one end, and being connected to the terminal plate. A case integrally formed so as to extend to the other end side facing the opening side; an intermediate conductor that fits in the opening and joins the terminal plate and the first lead terminal; A ladder-type filter comprising a lid body integrally formed with second lead terminals connected to a terminal plate, wherein the second lead terminals have an extending portion protruding outward of an opening, and A ladder-type filter having a substantially U-shaped cross section, which includes a solder fret forming portion that is bent substantially vertically downward from an extending portion and a wiring board joint portion that is bent from the solder fret forming portion to the case side. .