JPS6328364B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric filter that uses harmonics of stretching vibration in the longitudinal direction and a method for manufacturing the same. The object of the present invention is to provide a filter and a method for manufacturing the same.

In this type of piezoelectric filter, the nodes of vibration occur in the direction perpendicular to the vibration and across the width of the piezoelectric plate, so the leads can be held in contact with the entire width of the piezoelectric plate.
Therefore, it has the advantage of being able to support the piezoelectric plate more stably than a point contact type piezoelectric filter.

Conventionally, as this type of piezoelectric filter, the
It has been proposed in No.-102886 and Utility Model Application No. 149962-1983. In addition, products such as those shown in FIGS. 1 and 2 are provided. The illustrated piezoelectric filter has leads 5 and 5 facing each other with an insulating plate 3 in between.
A piezoelectric vibrator 1 with a ground electrode 11 and an input/output electrode 13 formed thereon is inserted between the leads 5 and 9, and a frame-shaped case 7 is placed over the vibration nodes of the vibrator 1 between the leads 5 and 9. The lower opening is filled with adhesive 17. Each lead of the input/output lead 5 and the ground lead 9 was bent below the insulating plate 3 and led out so as to be lined up in a straight line so that the piezoelectric filter could be easily attached to the circuit board.

Conventionally, the leads 5 and 9 were fixed with adhesive 17 instead of being planted on a substrate, etc. Despite the need to bend the leads as described above, the leads 5 and 9 that had been bent in advance were It is difficult to implant it on a substrate etc., and it is difficult due to production technology to make the distance between the leads 5 and 9 the same as the thickness of the vibrator 1;
This is because it was difficult to bend the leads 5 and 9 after they were implanted.

This piezoelectric filter with a conventional structure requires work such as arranging the leads 5 and 9 to sandwich the insulating plate 3 and storing them in the case 7, inserting the vibrator 1 into the narrow gap between the leads 5 and 9, and placing the leads 5 and 9 in the case 7. Adhesive 17 at the bottom of 7
It had to be manufactured through an extremely tedious work process that involved filling it with water. Furthermore, since the leads 5 and 9 are attached to the case 7 and the insulating plate 3 with the adhesive 17, their mechanical strength is not sufficient, and the amount of adhesive 17 may be uneven or uneven in adhesion. The problem was that it caused poor fixation.

Moreover, even if the leads 5 and 9 are firmly fixed to the case 7, etc., the upper parts of the leads 5 and 9 are likely to vibrate, causing the contact points to shift with the vibrator 1, causing fluctuations in the center frequency and loss. Although it is easier to apply and has better support than the point contact type, it still has the cause of unstable characteristics.

The present invention solves the above-mentioned drawbacks and provides a piezoelectric filter that has strong mechanical strength, stable characteristics, and is easy to mass produce, and a method for manufacturing the same. An example of this will be described below.

4 and 5 are an exploded perspective view and a sectional view of a piezoelectric filter according to the present invention. In the figure, 1
9 is a square substrate made of synthetic resin, with a recess 2 on the upper side.
1, and a locking portion 23 protrudes from both side edges of the recess toward the side of the board.

Three protrusions 25 are integrally formed with the substrate 19 at intervals at the lower portions of two other opposing sides of the substrate 19. An input/output lead 31 consisting of a pair of conductors having a protrusion 33 projecting upward from the inner bottom surface of the recess 21 is attached to the substrate 19 in parallel to each other.
9 and penetrated laterally. Therefore, the leads 3 are provided on the inner bottom surface of the recess 21 of the substrate.
Two protrusions 33 along the length direction of the recess 21
protrudes across the entire width of the 27 is the board 1
A protrusion 29 provided on the upper surface of the lead 9 is a protrusion formed on the inner wall of the recess 21 of the substrate following the protrusion 33 of the lead.

The piezoelectric vibrator 1 housed in the recess 21 of the substrate is
Input/output electrode 13 (fourth electrode) divided into input side and output side
(hidden in the figure) is formed on the main surface of an elongated ceramic plate, and a ground electrode 11 is formed on the back surface thereof. The vibrator 1 uses a harmonic wave (for example, twice) of the stretching vibration in the longitudinal direction of a ceramic plate, and the input/output electrode 13 is connected to the protrusion 33 by the width of the electrode 13 at the part corresponding to the node of the vibration.
It is arranged so that it is in line contact with the Figure 3 shows oscillator 1
This is a cross-sectional view schematically showing the vibration mode. In addition to being supported by the protrusions 33, the vibrator 1 is stably held within the recess 21 of the substrate because the side surfaces without the electrodes 11 and 13 are sandwiched between the two sets of protrusions 29.

The earth lead 43 is integrally formed with a pair of tongue pieces 35 having a dogleg shape in cross section and having a protrusion 37 that makes line contact with the earth electrode 11 of the vibrator 1 . A hole 41 is provided.

The ground lead 43 is fixed to the upper surface of the substrate 19 by thermally welding the tip of the protrusion 27 inserted into the hole 41. A pair of protrusions 37 of the earth lead 43 are in contact with respective portions of the earth electrode 11 corresponding to nodes of vibration of the vibrator 1 .
Therefore, via the vibrator 1, the input/output lead 3
The protrusions 33 of the earth lead 43 and the protrusions 37 of the earth lead 43 face each other, and the vibrator 1 is elastically held between the protrusions 33 and 37.

The holding plate 39 of the ground lead 43 is not only used to provide a hole 41 for fixing to the board 19, but also serves to prevent the lead 43 from being deformed or displaced when attached to the board 19. The ground lead 43 is arranged so as to protrude in parallel between the input/output leads 31 from the opposing sides of the board 19, and is provided with a step from the side of the holding plate 39 so as to be aligned with the input/output leads 31. It is set up and pulled out.

The piezoelectric filter of the present invention is completed by further covering the substrate 19 with a case 45 if necessary. case 4
5 is provided with a window 49 into which the locking portion 23 of the board 19 fits, ensuring secure fixation. In addition, a protrusion 2 of the board is attached to the lower side of the case 45.
5 and the leads 31 and 43 are formed, the leads 31 and 43 can be strongly held between the projecting body 25 and the slits 47 at the same time as a guide when fitting the cases together.

The above is the input/output lead 31 and the ground lead 4.
An example has been described in which the piezoelectric filter 3 is derived from two opposing surfaces of the substrate 19 and the piezoelectric filter is configured in a so-called DIP type. However, according to the present invention, simply the lead 31.
By simply changing the cutting method of 43, it is also possible to create a SIP type configuration in which each lead protrudes from one side of the board. Figure 10 shows the appearance of the piezoelectric filter.
In this example, A is a SIP type and B is a DIP type.

In the piezoelectric filter of the present invention described above, the input/output leads 31 are implanted in the lower part of the substrate 19, and only the protrusions 33 in contact with the vibrator 1 protrude from the recess 21, so that the leads 31 are firmly fixed. It is. Since the ground lead 43 is also fixed in surface contact with the upper surface of the board 19, the fixation is similarly ensured, and the lead 3
The mechanical strength of 1.43 becomes stronger and the position becomes constant. Therefore, the contact position with the vibrator 1 is also constant,
The positioning of the vibrator 1 in contact with the vibration node becomes easy. Moreover, since the vibrator 1 is placed on the two protrusions 33, it is easy to store the vibrator 1 in the recess 21, and the characteristics of the piezoelectric filter are stabilized.
Work efficiency is significantly improved. In addition, input/output lead 3
1 and the ground lead 43 can be led out from both sides of the board 19.
It has the convenience of being able to obtain a SIP type piezoelectric filter by cutting one side of the base of 3.

In the embodiment described above, the input/output leads 31 are connected to the substrate 1.
9, but conversely, the earth lead 4
3 may be implanted in the substrate 19, and the input/output lead 31 provided with the tongue piece may be fixed to the upper surface of the substrate 19. In that case, it is necessary to make the protrusion 37 of the tongue piece 35 of the ground lead protrude into the recess 21 of the board.

The leads planted on the substrate 19 are not limited to the structure in which the protrusions 33 are formed by bending a plate material. For example, the lead may be a rectangular wire having a rectangular cross section or a wire rod having an L-shaped cross section, whose ridges are used as protrusions. In short, it is sufficient as long as it has protrusions that make line contact with the vibration nodes of the vibrator 1. Furthermore, the recess 21 of the substrate 19 need not be a groove with both ends open as shown in FIG. 4, but may be a recess surrounded on all sides. However, if both ends are left open, it becomes easier to slide the housed vibrator 1 from the side, which has the advantage of making it easier to finely adjust the housed position of the vibrator 1.

Referring to the earth lead 43, the vibrator 1
As shown in Fig. 6, the tongue piece 35 that presses the oscillator 1 is made of a simple tongue piece instead of a dogleg shape, and when the vibrator 1 is pressed by the ridge 35' at the tip, unnecessary vibrations are eliminated and the filtering characteristics are improved. It was found that the condition was improved. The reason why the characteristics are improved in this way is that the protrusions 3
This is believed to be because when the vibrator 7 is brought into contact with the vibrator 1, the vibration of the vibrator 1 causes the portion beyond the protrusion 37 to vibrate unnecessarily, causing an adverse effect. A filtering characteristic A according to the embodiment shown in FIG. 6 and a filtering characteristic B according to the embodiment shown in FIG. 5 are shown in FIG. This figure also shows that the configuration of FIG. 6 can improve spurious response.

Further, for the earth lead 43, various fixing means can be used, not limited to heat welding using projections, and the pressing plate 39 is not essential. However, the presser plate 39 is effective in fixing to the substrate 19 as described above. Moreover, the ground lead holding plate 39 has a notch 40 formed therein as shown in FIG.
If the earth lead 43 is made to protrude from the protrusion, the positioning of the earth lead 43 becomes more reliable, and the tip of the protrusion 42 can be further firmly fixed by applying thermal melting or mechanical deformation. Note that this protrusion 40 is also useful in an earth lead that does not have the pressing plate 39 formed thereon.

Next, a method for manufacturing a piezoelectric filter according to the present invention will be explained. Although FIG. 8 and FIG. 9 show an outline of the manufacturing method of the present invention, it will be easier to understand if FIG. 4 is also referred to.

First, a large number of input/output leads 31 having protrusions 33 are punched out from a single conductive plate to form an input/output lead frame 49 (FIGS. 8A and 8B). On the other hand, a ground lead frame 51 (see FIG. C) is formed.

Then, as shown in FIG. 4D, a synthetic resin substrate 19 having a recess 21 and a protrusion 27 on the upper side is molded onto the input/output lead frame 49. At this time, 2
The protrusion 33 of the book input/output lead 31 projects upward from the inner bottom surface of the recess 21, and the main body of the input/output lead 31 laterally penetrates the lower part of the substrate 19 and is implanted.

Next, a vibrator 1 is made of a ceramic plate with input and output electrodes divided into an input side and an output side formed on the main surface and a ground electrode formed on the back side, and resonates with harmonics of stretching vibration in the longitudinal direction. , the recess 21 of the board
Insert inside. At this time, at the position corresponding to the vibration node of the vibrator 1, the protrusion 3 of the input side lead 31
3 and the input electrode 13, and the protrusion 33 of the output side lead 31 and the output electrode 13, respectively.

Thereafter, the earth lead frame 51 is placed on the input/output lead frame 49 as shown in FIG. 9 while the protrusion 27 of the board 19 is inserted into the hole 41 of the earth lead. At this time, the protrusion 37 of the tongue of the earth lead frame 51 is brought into contact with the earth electrode 11 at a position corresponding to a node of vibration of the vibrator 1. As a result, the protrusions 33 of the pair of input/output leads 31 pass through the piezoelectric vibrator 1 and at positions corresponding to the nodes of vibration.
and the protrusions 37 of the pair of ground leads 43 are in a state of facing each other.

Furthermore, the tips of the protrusions 27 are melted and thermally welded to the ground lead 43 to fix the ground lead 43 to the top surface of the board 19, and then the input/output leads 31 and the ground lead 43 protruding from the side surface of the board 19 are cut. Thus, the piezoelectric filter of the present invention is completed.

In addition, if necessary, a case 45 as shown in FIG. 4 may be covered. Also, lead 31.4
When cutting 3, lead frames 49 and 51
If one is cut at the roots R and R' of the lead frame, a DIP type piezoelectric filter can be obtained, and if one is cut at the root R and the other is at the root S of the substrate 19, a SIP type piezoelectric filter can be obtained. . For reference, see A in Figure 10.
A SIP type piezoelectric filter is shown, and a DIP type piezoelectric filter is shown in B. In the case of the DIP type, the leads 31 and 43 are bent in the direction of the arrow.

By the way, in the above embodiment, the input/output lead 31 is molded and the ground lead 43 is connected to the board 19.
Although it is arranged to overlap on the upper surface, it is also possible to do the opposite, that is, to mold the ground lead 43 and to overlap the input/output lead 31. Also, the board 1 of the ground lead 43
Fixing to the projection 9 is not limited to heat welding of the protrusion 27, but may be performed by conventionally known fixing means such as caulking.

As described above, in the manufacturing method according to the present invention, a substrate 19 having a recess 21 is molded on one lead frame (for example, an input/output lead frame) made by punching, and the vibrator 1 is housed in the recess 21 from above. After that, the process consists of stacking the other lead frame (for example, a ground lead frame) and cutting the leads. Therefore, after forming the board 19, it is only necessary to work from above the board 19, and the orientation of the board 19 is changed. This simplifies the work by eliminating the need for it.

Moreover, not only is it possible to use a lead frame, which significantly improves mass production, but also because the leads are molded and fixed to the board, when attaching the vibrator 1 to the board, the vibration nodes and the leads 31, 43
Accurately place transducer 1 in the desired position without misalignment.
can be stored.

The piezoelectric filter and its manufacturing method of the present invention have the above-mentioned useful effects.Finally, considering the piezoelectric filter, the piezoelectric filter can be used to connect other electronic components such as ICs and resistors. , unlike capacitors, etc., the piezoelectric vibrator itself makes mechanical vibrations, and the electrodes and leads of the filter that connect the vibrations with the electrode circuit are necessary for the vibrator to make the desired good vibrations without loss. A special structure is required to support the vibrator and contact the leads. Therefore, even when applying lead frame technology, for example, various measures were required. In this regard, the present invention uses harmonics of elongation vibrations, forms the contact portion of the leads into protrusions, fixes one lead in a mold, overlaps the other lead on the top surface of the molded substrate, and creates a gap between these two leads. This problem was solved by supporting the piezoelectric vibrator through line contact, and it is highly suitable for mass production and has great practical effects.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view showing a conventional example of a piezoelectric filter, Fig. 2 is a side sectional view thereof, Fig. 3 is a sectional view for explaining the state of vibration of a piezoelectric vibrator, and Fig. 4
The figure is an exploded perspective view showing one embodiment of the piezoelectric filter of the present invention, FIG. 5 is a side sectional view thereof, and FIG. 6 is a side sectional view of the main part of the piezoelectric filter showing another embodiment of the tongue piece.
Figure 7 is a characteristic diagram of the piezoelectric filter, and Figure 8 is ABCD.
and FIG. 9 are process diagrams showing the method of manufacturing the piezoelectric filter of the present invention, AB in FIG. 10 is a perspective view showing the appearance of the piezoelectric filter, and FIG. 11 is another implementation of the piezoelectric filter of the present invention. It is a perspective view showing an example. 1... Piezoelectric vibrator, 11... Earth electrode, 13
...input/output electrode, 19...substrate, 21...recess,
31...Input/output lead, 33...Protrusion, 35...
Tongue piece, 37...protrusion, 43...earth lead.

Claims (1)

[Claims] 1. A substrate molded from synthetic resin and having a concave portion on the upper side, an input/output electrode divided into an input side and an output side formed on the main surface, and a ground electrode formed on the back surface in the length direction. A piezoelectric vibrator that uses harmonics of stretching vibration,
an input/output lead made of a pair of conductors that contacts the input side and the output side of the input/output electrode, each having a first protrusion that serves as a point of contact with the input/output electrode;
and a ground lead in which a pair of tongue pieces having a second protrusion that contacts the ground electrode are integrally molded,
Either the input/output lead or the ground lead is planted at the bottom of the board, a pair of projections of the lead protrude upward from the inner bottom surface of the recess, and the piezoelectric vibrator is housed in the recess of the board. The electrode part on the bottom surface corresponding to the node of vibration is brought into contact with the protrusion, and the other lead is fixed to the top surface of the substrate, and the protrusion is brought into contact with the electrode on the top surface of the piezoelectric vibrator. A piezoelectric filter consisting of a protrusion on the input/output lead and a protrusion on the ground lead facing each other. 2. A step of forming an input/output lead frame by punching out a large number of input/output leads each having a first protrusion into a single conductive plate, and a grounding step provided with a pair of tongue pieces each having a second protrusion. A step of forming a ground lead frame by punching out a large number of leads from a single conductive plate, and a step of forming a synthetic resin substrate having a recessed portion on the upper side on the lead frame of either the input/output lead frame or the ground lead frame. By molding, the protrusions of the molded lead frame are made to protrude upward from the inner bottom surface of the recess, and the lead body is planted in the lower part of the board, and the lead frame is divided into an input side and an output side. Input/output electrodes are formed on the main surface, a ground electrode is formed on the back surface, and a piezoelectric vibrator that resonates at harmonics of longitudinal vibration is housed in a recess of the substrate, and the other lead is Fixing the frame to the top surface of the board, bringing the protrusion of the input side lead into contact with the input electrode, the protrusion of the output side lead with the output electrode, and the protrusion of the ground lead with the earth electrode, and
a step of making the protrusions of the pair of input/output leads and the protrusions of the pair of ground leads face each other at positions corresponding to nodes of vibration via the piezoelectric vibrator; and a step of cutting the leads of both lead frames from the frame. A method of manufacturing a piezoelectric filter consisting of: