JPH0528123U - Piezoelectric filter - Google Patents

Abstract

(57) [Summary] (Corrected) [Purpose] In a piezoelectric filter mounted on a printed circuit board in a surface mount type by bending the connecting legs of the terminal board in a crank shape, the mounting and fixing of the piezoelectric filter should be done in a uniform manner. [Structure] A bent base portion x, which projects from the insulating resin layer 9 of the connecting legs 3b and 4b and is bent downward, is formed on a printed circuit board P.
It is formed so as to be wider than the joining end portion y of the tip joined to.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a piezoelectric filter used in a mobile phone or the like using a plurality of piezoelectric resonators.

[0002]

[Prior Art]

 The piezoelectric filter includes a plurality of piezoelectric resonators, a plurality of terminal plates that abut the vibration nodes of these resonators to electrically and mechanically sandwich them, and an insulating plate as shown in FIGS. 4A and 4B, respectively. After constructing a ladder type filter circuit, the case opening surface that houses the inside of the case and guides the connecting legs of the input terminal plate and output terminal plate to the outside is sealed with an insulating resin layer such as epoxy resin, The structure is such that each connecting leg is bent into a crank shape (see Figs. 1 and 2) so that it can be mounted on a printed circuit board in a surface mount type.

[0003]

[Problems to be solved by the device]

 The connection leg is joined to the required conductive path of the printed circuit board with solder paste. If the thickness of the solder paste is large, it is easy to cause waxing and it is uneconomical. However, the size of the mobile phone cannot be miniaturized. Therefore, the thickness of the solder paste has been reduced, and recently, about 100 μm has been required. As a result, an unbonded portion of the solder is generated and the bonding strength is likely to decrease. To compensate for this, the thickness of the connecting leg is reduced, and as shown in FIG. Along with the thermocompression bonding, the upper surface of the bonding is also covered with the solder paste so that the bonding surface is substantially enlarged.

By the way, when the thickness of the connection leg becomes thin in this way, the connection leg is likely to be deformed by protruding from the insulating resin layer and bending downward or by an external impact thereafter, and this deformation causes connection to be bonded to the printed circuit board. There was a problem in that the flatness of the joint ends of the legs was uneven, and the piezoelectric filter was easily mounted in an inclined shape on the printed circuit board. The present invention aims to eliminate the above-mentioned problems associated with the thinning of the connecting legs.

[0005]

[Means for Solving the Problems]

 The present invention is characterized in that the connection leg of the terminal board is formed such that the bent base portion protruding downward from the insulating resin layer and bent downward is wider than the joint end portion joined to the printed circuit board. To do.

[0006]

[Action]

 Since the bending base part that is bent is wide, its holding power increases and is stable. Therefore, deformation due to external impact during bending or after bending is prevented as much as possible. Moreover, since the joint end is maintained at the conventional width, there is no problem in connection with the conductive path on the printed circuit board.

[0007]

【Example】

 The present invention will be described by taking as an example a piezoelectric filter F which constitutes a ladder filter circuit of the reverse L connection type shown in FIG. 4A. In FIG. 1, reference numeral 1 is a thick-walled small-capacity piezoelectric resonator arranged in a series branch of a filter circuit, 2 is a thin-walled large-capacity piezoelectric resonator also arranged in a parallel branch, the piezoelectric resonator 1, Rectangular terminal plates 3 to 6 for electro-mechanically sandwiching the resonators 1 and 2 by small protrusions 3a to 6a provided at the center are arranged on both sides of the plate 2. Of these, the terminal plate 3 is used for input, the terminal plate 4 is used for output, the terminal plate 5 is used for grounding, and the terminal plate 6 is used for intermediate connection. Further, strip-shaped connecting legs 3b and 4b projecting from opposite ends of the input terminal plate 3 and the output terminal plate 4 are provided. Reference numeral 7 denotes an insulating plate made of rubber or the like, which is appropriately arranged so that the piezoelectric resonators 1 and 2 can form the ladder type filter circuit shown in FIG. 4A, here, the case inner surface and the input terminal plate 3 which will be described later. Intervened between.

The piezoelectric resonators 1 and 2, the input terminal plates 3 to 6, and the insulating plate 7 are housed in a row in a metal case 8 and are connected to the connecting legs 3b of the input terminal plate 3 and the output from the opening surface 8a. The connection leg 4b of the terminal plate 4 is led out to the outside. This metal case 8 is in contact with the grounding terminal plate 5 to serve as a grounding terminal and also has a strip shape protruding from the center of one side edge of the opening surface 8a in the same direction as the input terminal side connecting leg 3b and the output terminal side connecting leg 4b. The ground connection leg 8b is provided. Further, each length of the connecting leg 3b and the connecting leg 4b is set to be substantially the same as the ground connecting leg 8b when bent in a crank shape.

The opening surface 8a of the metal case 8 is filled and cured with an insulating resin layer 9 made of an elastic filler such as an elastic epoxy resin via a thin piece 11 (not essential) such as paper, The opening surface 8a is closed. After filling the insulating resin layer 9, the connecting legs 3b and 4b are bent in a crank shape. As shown in FIG. 3, when the connection leg 3b and the connection leg 4b have an extremely thin shape of about 0.1 mm, when the solder paste layer f is heat-pressed, the solder paste reaches the upper surface and is bonded. It is designed to maintain strength.

By the way, in the connecting legs 3b and 4b, as shown in FIG. 2, a bent base portion x which is protruded from the insulating resin layer 9 and bent downward is made wide, and a print portion is provided via a taper portion z. The joining end portion y of the tip joined to the substrate P has a narrow width as before. Therefore, when the bending base part x is bent, its wide shape increases the holding force, and a stable right-angled bending can be performed. Even after the bending, the deformation due to an external impact is generated. Hard to beat Therefore, the flatness of the joint end portion y is improved, and when the joint is made to the required conductive path of the printed board P via the solder paste layer f, the piezoelectric filter F is held evenly with respect to the printed board P. Thus, the piezoelectric filter F having the above structure is uniformly mounted on the upper surface of the printed wiring board P by the surface mount type as shown in FIG.

In the above example, one serial branch piezoelectric resonator 1 and one parallel branch piezoelectric resonator 2 are used, but a plurality of piezoelectric resonators 1 and 2 are provided as in the filter circuit of FIG. 4B. It can also be applied to a piezoelectric filter configured by. Further, in the above example, the case made of metal is used, but when the case made of plastic is used, the ground connection leg is projected from the center of one side of the ground terminal plate. In this case as well, the bent base x Is wider than the joint end portion y.

[0012]

[Effect of the device]

 As described above, according to the present invention, in the piezoelectric filter F mounted on the printed circuit board in the surface mount type by bending the connecting leg of the terminal plate in a crank shape, the piezoelectric filter F protrudes from the insulating resin layer of the connecting leg and goes downward. Since the bending base portion x to be bent is formed wider than the joining end portion y at the tip end to be joined to the printed circuit board, even when the connecting leg is extremely thin, it can be bent. Alternatively, there is an excellent effect that the subsequent deformation is unlikely to occur, the flatness of the joint end portion y is maintained, and the joint end portion y can be uniformly mounted on the upper surface of the printed board P by the surface mount type.

[Brief description of drawings]

FIG. 1 is a vertical side view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a mounting state on a printed wiring board P.

FIG. 3 is a vertical cross-sectional side view showing a joining state of a joining end portion y with a solder paste layer f.

FIG. 4A is an inverse L connection type ladder filter circuit diagram.

FIG. 4B is a multi-stage connection ladder filter circuit diagram.

[Explanation of symbols]

 1 Series Branch Piezoelectric Resonator 2 Parallel Branch Piezoelectric Resonator 3 Input Terminal Plate 3b Connection Leg 4 Output Terminal Plate 4b Connection Leg 8 Metal Case 9 Insulating Resin Layer x Bend Base y Joint End F Piezoelectric Filter

Claims (1)

[Scope of utility model registration request] 1. A plurality of piezoelectric resonators, and a plurality of terminal plates that abut the vibration nodes of the resonators and electrically and mechanically sandwich the terminal plates.
Insulating plates that are inserted at appropriate places to form a predetermined filter circuit, a case that houses these parts in a column and a leg portion of each terminal plate is led out from the opening surface to the outside, and an opening surface of the case A piezoelectric filter which is composed of an insulating resin layer that seals in a substantially flush manner, is formed by bending the connecting legs of each terminal plate into a crank shape, and is mounted on a printed circuit board in a surface mount type by the connecting legs. The piezoelectric filter is characterized in that the connecting leg is formed such that a bent base portion protruding from the insulating resin layer and bent downward is wider than a joint end portion joined to the printed circuit board.