JPH04102323U - Ladder type ceramic filter - Google Patents

Abstract

(57) [Summary] [Objective] The object is to provide a ladder-type ceramic filter in which the desired connection between resonators can be easily achieved by a simple lamination process, and the airtightness inside the case is improved. [Structure] A ladder-type ceramic filter in which a laminate consisting of a series resonator, a parallel resonator, and a terminal plate in contact with the resonator is housed in a housing-like case, and connected to the terminal plate. A lead terminal is integrally formed with the housing-like case by insert molding, and extends outward from the inside of the case. Therefore, airtightness is improved between the lead terminal and the case, and between the lid and the case.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a ladder type ceramic filter.

0002

[Conventional technology]

For example, intermediate frequency filters (455/45 A ladder type ceramic filter is used as the 0kHz filter.

0003 As this type of filter, Japanese Utility Model Application No. 2-38820 discloses a ceramic series filter. A laminate consisting of a resonator, a parallel resonator, and a terminal plate that contacts them. A case that stores the laminate, and a lid that closes the opening of the case. It is shown. In this filter, the laminate connects the resonators in series or parallel. Contains a special U-shaped terminal board for

0004 The filters mentioned above have special U-shaped terminals for connecting in series or parallel. Therefore, while laminating sequentially in the case, and the desired connection is difficult to achieve. Yes, the laminate with the desired connections must be stored in the case. Ta.

[0005] In order to solve the difficulty of stacking the laminates, the inventors of the present invention created a storage case in advance. A connecting body is provided on the inner wall of the base to achieve parallel connection, and the parallel connections are connected sequentially from the opening side. Ladder-type ceramic that allows the specified connection to be achieved simply by stacking the pendulum and terminal board. (Japanese Patent Application No. 2-92317).

[0006]

[Problems with conventional technology]

In the ladder type ceramic filter mentioned above, it is connected to the specified terminal plate and then connected to the outside of the case. An extending lead terminal extended from the opening side, and the opening was fitted with a sealing lid.

[0007] Therefore, when the lid is fitted, the lead terminal extending from the opening side is pulled out of the lid. In order to Place it on the side wall of the case and fit the lid, and then Therefore, the gap between the lead terminal and the lid was filled with sealing resin.

[0008] However, the metal that is the lead terminal (phosphor bronze, etc.) and the sealing resin (epoxy) Because the coefficient of thermal expansion differs greatly between resins (resins, etc.), after sealing the lid, When connecting a ladder type ceramic filter to a circuit board by soldering, A peeling phenomenon occurs between the terminal and the sealing resin, and the airtightness is greatly reduced. In this way, if the airtightness deteriorates, solder flux and cleaning fluid can enter the inside of the case. This results in a significant decrease in reliability.

[0009] This invention was devised in view of the above-mentioned problems, and its purpose is to reduce the distance between resonators. The desired connection can be easily achieved by simply stacking the laminates, and the inside of the case is airtight. The present invention provides a ladder-type ceramic filter with improved performance.

0010

[Specific measures to solve the problem]

The ladder type ceramic filter according to the present invention consists of a series resonator, a parallel resonator, and A laminate consisting of the resonators and the contacting terminal board is housed in a housing-like case. A ladder-type ceramic filter, wherein the housing-like case is attached to the terminal plate. The lead terminals to be connected are molded so that they extend from the inside of the case to the outside.

[0011]

[Effect]

In the ladder-type ceramic filter according to the present invention, the lead terminal is attached to the housing-like case. By insert molding that is integrated during molding, the bottom side of the housing-like case and does not extend from the opening surface side where the lid is sealed. For this reason, conventional There is no need to fill the space between the lead terminal and the lid body with sealing resin as shown in the figure. , the peeling phenomenon between the lead terminal and the sealing resin that accompanies this can be completely eliminated.

0012 Also, since the lead terminal is fixed integrally with the case, it can extend inside the case. , and since the connection parts that come into contact with each terminal board are also fixed, the weight of the resonator and terminal board is reduced. The tatami work becomes easier and the electrical contact with the terminal board becomes reliable.

[0013]

【Example】

Hereinafter, the ladder type ceramic filter of the present invention will be explained using the drawings. Figure 1 is a cross-sectional view of the ladder-type ceramic filter of the present invention, and Figure 2 is a cross-sectional view of the ladder-type ceramic filter of the present invention. It is an exploded perspective view. In the example, a four-element ladder type ceramic filter will be described. I will explain.

[0014] In the figure, 1 is a ladder type ceramic filter. The filter 1 includes a laminate 2 consisting of a plurality of resonators and terminal boards, and a casing that houses the laminate 2. It includes a body case 3 and a sealing lid 4.

[0015] The laminate 2 includes, from the bottom of FIG. 1, a first terminal plate 5, a first series resonator 6, and a second terminal. Plate 7, second series resonator 8, third terminal plate 9, first parallel resonator 10, fourth terminal plate 11, a second parallel resonator 12, a fourth terminal plate 13, and a spring terminal 14. There is.

[0016] Each terminal board 5, 7, 9, 11, 13 is a metal made of approximately rectangular phosphor bronze or the like. It is a member, and a projection protruding toward each resonator 6, 8, 10, and 12 is formed at its center. has been done. Note that there are protrusions on both sides of the terminal plates 7, 9, and 11 sandwiched between the resonators. Since it is necessary to form a You may also do so.

[0017] In addition, each resonator 6, 8, 10, 12 is shown on the terminal board 5, 7, 9, 11, 13. Connecting extension parts 5a, 7a, 9a, 11a, 13a so that the electrical structure diagram shown in 3 is obtained. is formed. As will be described later, the inner wall of the case 3 has connection extensions 5a and 7. Lead terminals 25, 26, 27 and connection leads that connect to a, 9a, 11a, 13a A piece 28 is formed.

[0018] Each resonator is a piezoelectric ceramic member such as PZT, and depending on the filter characteristics , the thickness and size of each are set.

[0019] The spring terminal 14 is a metal member having the same shape as the terminal plate 13, and is located inside the case 3. protrudes in the direction. This spring terminal 14 allows the laminate 2 to be housed in the case 3. After that, when the opening is sealed with the lid body 4, each resonance occurs with each terminal plate 5, 7, 9, 11, 13. The protrusions allow the children 6, 8, 10, and 12 to come into complete contact with each other.

[0020] The housing-like case 3 is made of resin such as PPS, and has four openings 21 on one side. It consists of a side surface and a bottom surface. There is a step 22 near the opening 21 on the inner wall of the case 3. is formed, and the lid body 4 fits into this step 22 portion.

[0021] Lead terminals 25, 26, and 27 extend from the bottom surface of the case 3. This resource The lead terminals 25, 26, and 27 extend to a predetermined height on the inner wall of the case 3, and The lead terminal 25 contacts the connection extension 5a of the terminal board 5, and the lead terminal 26 contacts the connection extension 5a of the terminal board 9. The lead terminal 27 contacts the connection extension 11a of the terminal board 11. Continue.

[0022] Furthermore, a connection lead piece 28 is fixed to the inner wall of the case 3. The cable piece 28 connects with the connection extension 7a of the terminal board 7 and the connection extension 13a of the terminal board 13. I'm touching it.

[0023] Case 3, lead terminals 25, 26, 27, and connection lead piece 28 are connected to case 3. When molding, for example, by insert molding, the lead terminals 25, 26, 27 and the connection lead piece 28 are integrally molded. Furthermore, regarding the connection lead piece 28, If so, it may be placed by press-fitting after molding the case 3.

[0024] As described above, from the opening 21 of the case 3, the first terminal plate 5, the first series resonance child 6, second terminal plate 7, second series resonator 8, third terminal plate 9, second parallel resonator 1 0, the fourth terminal plate 11, the first parallel resonator 12, and the fourth terminal plate 13 are superimposed and laminated. By simply doing this, a ladder type ceramic filter having the desired circuit shown in FIG. 3 can be achieved.

[0025] Finally, the spring terminal 14 is placed and the sealing lid 4 made of resin is placed on the case 3. If the ladder type ceramic filter is fitted into the step 22 formed near the opening 21 of the The data is completed. Note that the gap between the sealing lid 4 and the step 22 is filled with epoxy resin or the like. By interposing the resin adhesive 23, a strong and airtight seal can be achieved.

[0026] According to the present invention, the lead terminals 25, 26, and 27 are integrally molded with the case 3 and penetrate through the case 3. Therefore, as in the conventional case, the lead terminal is not passed through the lid body 4. holes and notches for connecting the lead terminals 25, 26, and 27 between the lid body 4 and the housing 3. There is no need to fill with airtight resin while sandwiching the parts. For this reason, heat application in post-process , for example, when soldering a ladder-type ceramic filter to a printed circuit board. No peeling occurs due to the difference in thermal expansion coefficient between the resin and the lead terminal. stomach.

[0027] In addition, in the present invention, the lead terminals 25, 26, and 27 are Since it is fixed with insert mold, case 3 and lead terminals 25, 26, 2 There is no peeling or gap between the casing 7 and the casing 7, and a sufficient airtight seal is maintained.

[0028] Furthermore, the lid body 4 that seals the opening 21 has no processing such as through holes or cuts. This is not necessary, and the lid 4 and the case 3 are joined together using the resin adhesive 23. subordinate Therefore, since the lid body 4, case 3, and resin adhesive 23 are all made of resin, their heat Since the expansion coefficient is approximated, even if heat is applied in the post-process, peeling etc. will not occur. This creates a ladder-type ceramic filter with high airtightness as a whole.

[0029] In the above embodiment, the bottom side of the case 3 generally has a planar dimension compared to a parallel resonator. Series resonators 6 and 8 having a small modulus are arranged. The dimensions of the case 3 storage compartment are flat. Since it is set considering the parallel resonators 10 and 12 with large surface dimensions, the series resonator 5 , 7 and the inner wall of the case 3. For this reason, as shown in Figure 4, On the bottom side of the inner wall of the case 3 is a holder protrusion for positioning the series resonators 6 and 8. 29 is formed.

[0030] This causes the protrusions of the terminal plates 5, 7, and 9 that come into contact with the series resonators 6 and 8 to resonate in series. It is possible to stably contact the centers of the children 6 and 8.

[0031] In the above embodiment, the lead terminals 25, 26, and 27 extend from the bottom of the case 3. However, in addition, it extends from the inside to the outside through the four sides of case 3. It doesn't matter if you do it. In addition, the external ends of the lead terminals 25, 26, and 27 are bent into an L shape, and the printed circuit This is a surface-mounted ladder-type ceramic filter that connects to the surface of the circuit board. In addition, connect the lead terminals 25, 26, 27 toward the center of the back surface of the housing 3, or The lead terminals 25 may be bent in a J-shape along the outer wall of the case 3. Ladder type ceramic that penetrates the printed circuit board without bending 26 and 27. It does not matter if it is a filter.

[0032] Furthermore, in the above embodiment, two series resonators and two parallel resonators were used. Although we have explained the 4-element ladder type ceramic filter, it is possible to increase the number of connecting lead pieces. Thus, a ladder type ceramic filter having four or more elements may be constructed.

[0033]

[Effect of the idea]

As described above, according to the present invention, the lead terminal extends from the inside of the case to the outside. , and because it is integrally molded with the case, airtightness is maintained between the lead terminal and the case. will improve. In addition, the case opening is made of a single plate with no notches or the like. Since it is fitted with a sealing lid, the airtightness between the lid and the case is improved, and the overall A ladder-type ceramic filter with high airtight reliability is achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a ladder-type ceramic filter of the present invention.

FIG. 2 is an exploded perspective view of the ladder-type ceramic filter of the present invention.

FIG. 3 is an electrical structural diagram of a ladder-type ceramic filter.

FIG. 4 is a plan view of the opening side of the case of the ladder-type ceramic filter of the present invention.

[Explanation of symbols]

1 Ladder type ceramic filter 2 Laminated body 3 Case 4 Sealing lid 5, 7, 9, 11, 13 Terminal plates 6, 8 Series resonators 10, 12 Parallel resonators 25, 26, 27 Lead terminals

Claims (1)

[Scope of utility model registration request] 1. A ladder-type ceramic filter in which a laminate including a series resonator, a parallel resonator, and a terminal plate in contact with these resonators is housed in a housing-like case, wherein the housing is 1. A ladder-type ceramic filter characterized in that a shaped case is molded so that lead terminals connected to the terminal plate extend from inside the case to the outside.