JPH0141224Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a surface wave device, which is easy to manufacture and has improved performance by mounting a surface wave element on an electrode printed on a ceramic substrate and covering the element with a metal cap. The purpose is to provide a device that can

In general, filters used for channel separation of television transmission signals include, for example, L,
There is a combination of C elements, but this has the problem that it cannot produce sharp characteristics due to the low Q value, and even if it can produce the desired characteristics, it requires a large number of networks and becomes large. The problem was that the cost would be high.

In order to solve the above problems, conventional surface wave filter devices use a surface wave element obtained by forming comb-shaped electrodes on a piezoelectric material, for example, with four terminals (2
This is the so-called CAN method, in which a terminal (one for input, the other two for output) is fixed to the top surface of a vertically planted metal board (however, the terminals and the board are insulated), and then covered with a metal cap. Although this method has the good effect of completely surrounding the surface wave element with metal and providing complete shielding, the distance between the terminals is small, so the transmitted wave passing through the surface wave element is Another drawback is that a direct wave is generated in which a signal is directly transmitted between the input and output terminals, and a ripple phenomenon occurs due to the signal that is the sum or difference of these two waves.

In order to eliminate the above-mentioned drawbacks, the present applicant previously printed and formed electrodes for signal input/output and grounding on a single ceramic substrate using Utility Application No. 10373/1983 entitled "Surface Wave Device", and After forming an insulating layer in a ring shape, a surface wave element is fixed to the exposed part of the grounding electrode, and a metal cap with adhesive is bonded to the ring-shaped insulating layer to cover the surface wave element. We proposed a method in which the material was molded with resin.

According to the above-mentioned example of the prior application, by arranging the input electrode and the output electrode apart from each other in advance, it is possible to prevent the above-mentioned direct wave and suppress the ripple phenomenon. Since the surface wave element is almost completely isolated from the outside air by the cap, the thin aluminum wires that connect the surface wave element and the terminals or electrodes may react with moisture in the outside air and corrode, causing the wire bonding part to corrode. It is possible to prevent inconveniences such as detachment or increased contact resistance resulting in characteristic deterioration.

However, according to the above-mentioned prior application, an adhesive layer is interposed between the insulating layer and the metal cap, and the mold layer,
A small amount of moisture penetrates into the cap through the adhesive layer, and the above deterioration of characteristics is still incompletely prevented.
Furthermore, in order to bond the cap, it is necessary to press the cap against the board in an atmosphere of, for example, 200°C for about an hour, which increases the number of man-hours and also causes the insulating layer to be destroyed by the pressing pressure, resulting in conductivity between the cap and the electrode. In addition, since it is necessary to provide a flange on the periphery of the cap that is bonded facing the substrate, the flange increases the area of the substrate, leading to problems such as an increase in the size of the device. .

Additionally, since the surface wave element is covered with a metal cap, the shielding performance is improved, but the cap is not at ground potential, so it is not possible to provide reliable shielding, and there is a risk that external disturbances may infiltrate. There was a problem. Furthermore, since the surface wave device is a small device, there is a problem in that it is difficult to properly position and attach the cap to a predetermined position on the board.

The present invention solves the problems of the above-mentioned prior application, and embodiments thereof will be described below with reference to the drawings.

FIG. 1 is a perspective view of a substrate and a metal cap constituting one embodiment of the surface acoustic wave device according to the present invention.
The manufacturing steps will be explained below in order.

In the figure, a surface acoustic wave device 1 is used as a bandpass filter for an intermediate frequency of a television, or a bandpass filter for an RF modulator for converting a high frequency signal such as a video signal, and has a substrate 2.

As shown in FIGS. 1 and 3, the substrate 2 is in the form of a green sheet, after which a pair of recesses 2a are formed in the vicinity of both sides, and then fired and hardened. Subsequently, as shown by diagonal lines on the upper right in FIG. 1, a pair of input electrodes 3 and 4 and a pair of output electrodes 5,
After printing and forming the negative earthing electrodes 7 and 6, they are temporarily dried.

Next, as shown by the satin pattern in FIG.
For example, an insulating layer 8 made of borosilicate glass with a predetermined thickness is printed and formed on the upper surface including a part of the electrodes 3 to 7 .
a and the lower end 7b, but the upper end 7
a, the lower end 7b remains exposed. At this time, as shown in FIGS. 1 and 2, the insulating layer 8 is also applied to predetermined portions of the input/output electrodes 3 to 6 where wire bonding will be performed later or terminal pins will be provided. It is not attached and remains exposed.
Subsequently, the substrate 2 is temporarily dried and then fired at a temperature of 800 to 900°C to stabilize the electrodes 3 to 7 and the insulating layer 8.

Next, a ring-shaped conductive layer 9 is formed by printing on the upper surface of the insulating layer 8 including the upper end 7a and lower end 7b of the earthing electrode using silver paste as shown by diagonal lines in the upper left corner of FIG. 1, and after temporary drying. Above 800~900℃
It is fired at a temperature of At this time, the conductive layer 9 is electrically connected to the grounding electrode 7 at the upper end 7a and lower end 7b of the grounding electrode 7, and has a ground potential.

Next, a surface wave element 12 formed by forming comb-shaped input and output electrodes 11a and 11b on the surface of the plate-shaped piezoelectric material 10 is bonded to the upper surface of the central exposed portion of the grounding electrode 7 using a predetermined conductive bonding material. 150
It is dried and fixed at temperatures between ℃ and 180℃. After that, a pair of comb tooth portions of the input electrode 11a of the element 12 are connected to the substrate 1 by wires 13 each having a diameter of about 30μ to 40μ.
The input electrodes 3 and 4 are bonded using an ultrasonic bonder. Similarly, the output electrode 11b is also wire bonded to the output electrodes 5 and 6 of the substrate 1.

On the other hand, as shown in FIG. 1, a metal cap 14 made of a material such as a steel plate and having a pair of protrusions 14a at the lower ends of both sides covers the surface wave element 12 with respect to the substrate 2 and has a pair of protrusions. The parts 14a can be easily positioned and attached in a state where they are respectively engaged with the pair of recesses 2a. At this time, the ring-shaped lower end of the cap 14 approximately coincides with the ring-shaped conductive layer 9.

Subsequently, as shown in FIG. 2, the lower end of the outer periphery of the cap 14 is soldered with solder 15 over the entire circumference, so that the cap 14 and the conductive layer 9 are electrically connected and fixed.
In addition, terminal pins 21 are attached to each electrode 3 to 7 of the substrate 2 in FIG.
Solder and secure parts a to 21e. Further, as shown in FIG. 2, resin is molded on the surface of the substrate 2 and the cap 14, a mold layer 22 is formed, and a package is applied.

In this way, the surface acoustic wave device 1 is completed. According to this, a metal conductive layer 9 is interposed between the metal cap 14 and the insulating layer 8, and the joint between the conductive layer 9 and the cap 14 is covered with the solder 15. Therefore, although moisture in the outside air can penetrate the mold layer 22, it is extremely difficult to penetrate into the cap 14, and deterioration of characteristics can be almost completely prevented.
Since it is fixed by solder 15, the time required for installation is shortened, and the number of man-hours can be reduced. Also, there is no need to press the cap 14, and there is no need to press the cap 14 and the input/output electrodes 3 to 6 due to breakdown of the insulating layer 8. Inconveniences such as short circuits are eliminated, and the soldering of the cap 14 eliminates the need to provide a flange around the periphery of the cap, making it possible to reduce the area of the board 2 and downsizing the device 1.
Since the earthing electrode 7 is electrically connected to the earthing electrode 7 through the upper ends 7a and 7b, and the earth potential is reliably set, the shielding performance is high and the performance of the device 1 can be improved. Similarly, in FIG. 1, the hot side input electrodes and terminals 3, 21a and the hot side output electrodes and terminals 6, 21e are arranged close to both sides of the substrate 2 with a large distance apart from each other. Direct waves are reduced and ripple phenomena can be suppressed.

Next, a procedure for efficiently manufacturing the surface acoustic wave device 1 will be explained. First, as shown in FIG. 4, a plurality of x-direction snap lines 24a and a plurality of y-direction snap lines 24b are carved into a large-sized ceramic substrate 23 to form a plurality of portions corresponding to the single substrate 2. Next, the electrodes 3 to 7, the insulating layer 8, and the conductive layer 9 are simultaneously formed on the portions corresponding to the plurality of substrates 2, and then the surface wave element 12 and the cap 14 are sequentially bonded, and then separated along the snap lines 24a and 24b. Then, a plurality of surface wave devices 1 are formed. According to this, mass production can be performed and manufacturing costs can be reduced.

Incidentally, the metal cap 14 may be tin-plated in advance, for example, so that the solder 15 can be soldered more securely.

Furthermore, the solder 15 is not limited to the method of sequentially soldering to the outer periphery of the cap 14, but may also be formed by fitting a solder ring that matches the outer shape of the cap 14 to the outer periphery of the cap 14 in advance and then heating and melting it. Good too.

As mentioned above, according to the surface acoustic wave device of the present invention, the metal conductive layer is interposed between the cap and the insulating layer, and the joint between the conductive layer and the cap is covered with solder, so that moisture in the outside air is prevented. It is extremely difficult to enter the cap, preventing property deterioration, and since the cap is attached by soldering,
Not only can the number of work steps be reduced, but also the product yield can be improved without the risk of breaking the insulating layer and short-circuiting the cap and input/output electrodes.Also, it is possible to provide a flange on the cap by soldering the cap in its fillets. Since the cap is electrically connected to the grounding electrode through the conductive layer and is securely at ground potential, the shielding performance is large and the performance can be improved. At the same time, a positioning protrusion is formed on the metal cap, and therefore, the metal cap can be easily positioned by simply engaging the positioning protrusion with the positioning recess, improving the installation work efficiency. It has the characteristics of being transparent.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a substrate and a metal cap constituting one embodiment of the surface acoustic wave device according to the present invention, FIGS. The figure is a diagram showing a process of manufacturing a plurality of the above devices in one piece. 1...Surface wave device, 2, 23...Substrate, 3, 4
...Input electrode, 5, 6...Output electrode, 7...Grounding electrode, 7a, 7b...Top and bottom ends of grounding electrode,
8... Insulating layer, 9... Conductive layer, 12... Surface wave element, 13... Wire, 14... Metal cap, 1
5...Solder, 21a-21e...Terminal pin, 22
...Mold layer, 24a, 24b...Snap line.

Claims (1)

[Scope of utility model registration request] an insulating substrate having a positioning recess formed therein;
A plurality of electrodes for signal input/output and grounding, each of which is formed by adhering to the upper surface of the substrate using a conductive material, and a connection portion between the terminal of the signal input/output electrode and a connection portion with the surface wave element are exposed, and Adhesively formed on the upper surface of the signal input/output and earthing electrodes by exposing either the upper end or the lower end, or both the upper and lower ends, and exposing the portion connected to the terminal. an insulating layer, and a ring-shaped conductive layer formed on the upper surface of the insulating layer so as to be electrically insulated from the plurality of signal input/output electrodes and to be electrically connected to the exposed portion of the grounding electrode. and,
surface wave elements fixed to the upper surface of the exposed portion of the grounding electrode and electrically connected to the exposed portions of the signal input/output electrode, and a positioning protrusion that engages with the positioning recess; A metal cap is disposed on the top surface of the conductive layer to cover the surface wave element, and is conductively fixed to the top surface of the conductive layer by being soldered to cover the entire outer periphery of the joint with the conductive layer. A surface wave device consisting of