JPS631771B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In order to connect the drive electrode of a rectangular piezoelectric ceramic plate having a drive electrode on one side and a floating electrode on the other side to an external lead terminal, the present invention has a ground terminal in the center and a ground terminal on both edges. A large number of 3-terminal ceramic filters with input and output terminals are lined up so that the terminal surfaces are in the same direction, and conductivity is applied only in the thickness direction between the terminal surfaces and the three external lead terminals. This is a terminal connection method for edge mode ceramic filters in which composite conductive rubber, which is made up of alternate conductive rubber and conductive rubber that is conductive in all directions, is sandwiched and held in pressure contact.

For intermediate frequency amplification circuits in radios and other wireless devices, edge mode vibration is used, in which vibration energy is concentrated near the longitudinal ends of rectangular piezoelectric ceramic plates, and the resonant frequency is determined by the width of the plate. An edge mode ceramic filter is used. As shown in FIG. 1a, this filter unit has driving electrodes 2, 3 and 4 provided at one end of one surface of a piezoelectric ceramic plate 1 polarized in the thickness direction, and extending from the drive electrodes 2, 3 and 4. Input terminal 2', ground terminal 3' and output terminal 4' for external connection are drawn out at the other end, and drive electrodes 2, 3, 4 are connected to the other side as shown in b. Floating electrodes 5 and 5' are provided opposite each other to constitute a three-terminal type filter. Edge Mode
Since the ceramic filter is symmetrical, the input terminal 2' and output terminal 4' may be reversed.
Further, even if the length of the piezoelectric ceramic plate is set to 2 to 3 times the width and is fixed with a length of approximately 1.5 times the width left from the end face where the drive electrode is located, there is almost no effect on the filter characteristics.

Conventionally, in order to connect a large number of edge mode ceramic filters in cascade, they are fixed to the base board 9 in the same direction as shown in FIG. 2, and each adjacent output terminal 4', input terminal 2', and ground After soldering the terminals 3' with the lead wire 10, solder the lead terminal 2'' to one of the input terminals, the lead terminal 3'' to the ground terminal, and the lead terminal 4'' to the output terminal.Also, another method is used. As shown in FIG. 3a, each input terminal 2' of the filter unit is
Solder the external lead terminals 2'', 3'', and 4'' to the ground terminal 3' and output terminal 4', form a conductive pattern 11' on the printed circuit board 11 as shown in Figure 3b, and assemble the filter unit. Insert the lead terminals and solder them. However, the former method requires soldering a large number of lead wires 10, and the latter method requires many holes in the printed circuit board, resulting in a large number of pins, etc. This method also has the drawbacks of extremely poor workability, increased man-hours, and lack of reliability since there are many soldering points.

The present invention relates to a terminal connection method that reduces these drawbacks and connects composite conductive rubber plates to external terminals by stacking them on the input, ground, and output locations of a filter unit.

The terminal connection method of the edge mode ceramic filter of the present invention is as shown in FIG. Using a composite conductive rubber plate 6 having alternating configurations, it is assembled as shown in the three-element, three-terminal type embodiment shown in FIG. 5 and its sectional view in FIG. This filter unit has the ground terminal 3' in the center as shown in Figure 1, so
The three filter units are placed with the terminal surfaces for external connection in the same direction and on the same surface, and the composite conductive rubber plate 6 shown in FIG. and the output terminal 4', and the ground terminal 3' of each filter unit is stacked on the anisotropic region 8. Further, an isotropic region 7 of the conductive rubber plate 6 that contacts the input terminal 2' and output terminal 4' of the filter unit at one end.
The input lead terminal 2'' and the output lead terminal 4'' are stacked on top of each other, and the comb-shaped ground lead terminal 3'' is stacked on the area 8 in contact with the ground terminal 3' of each filter unit. By press-holding, cascade-connected filters can be obtained.

As described above, the present invention allows external connections to be made using comb-shaped and rod-shaped lead terminals made of composite conductive rubber and metal, which have a simple structure, and does not require processing that is difficult to work with such as soldering. The lead terminals are connected to ceramics via conductive rubber.
Since the electrodes are held in pressure contact with the filter, there is no peeling of the electrodes due to friction, and a highly reliable multi-element filter with excellent vibration and shock resistance can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram of the electrode pattern of an edge mode ceramic filter unit, where a is a surface view and b is a surface view.
is a back view, Figure 2 is a plan view showing an example of the conventional terminal connection method, and Figure 3 is a of another example of the conventional terminal connection method.
is a plan view, b is a diagram of a conductor pattern on a printed circuit board, FIG. 4 is a perspective view of a composite conductive rubber used in the terminal connection method of the present invention, and FIG. 5 is a plan view of an embodiment of the terminal connection method of the present invention. Figure 6 is A in Figure 5.
-A' sectional view. In the figure, 1: piezoelectric ceramic plate, 2, 3,
4: Drive electrode, 5, 5': Floating electrode, 2': Input terminal, 3': Earth terminal, 4': Output terminal, 2'',
3″, 4″: Lead terminal, 6: Composite conductive rubber,
7: Isotropic region, 8: Anisotropic region. Note that the symbols appended with a, b, and c correspond to the symbols for each of the three element filters.

Claims (1)

[Claims] 1. Near the end of the same surface of a rectangular piezoelectric ceramic plate, a large number of three-terminal ceramic filters each having a ground terminal in the center and an input terminal and an output terminal on both edges are arranged on the same surface; Composite conductive rubber, which is made up of conductive rubber that is conductive only in the thickness direction and conductive rubber that is conductive in all directions, is sandwiched between the external metal lead terminal and held in pressure contact. A terminal connection method for a multi-element edge mode ceramic filter characterized by the following.