JPH0590883A - Surface acoustic wave device and its preparation - Google Patents

Abstract

PURPOSE:To upgrade the seal performance for the functional surface of a surface acoustic wave device and to upgrade the reliability of the surface acoustic wave device by securing a predetermined oscillation space on the functional surface of the surface acoustic wave device without using a particularly complicate fabrication method. CONSTITUTION:In a surface acoustic wave device 3, a functional surface 3a where a tandem type electrode 2 is prepared is mounted opposite to a substrate 5 where an external lead-out electrode 8 is disposed. The surface acoustic wave device 3 is mounted on the substrate 5 via a ring member 10 made of elastic material placed at a position surrounding the tandem type electrode 2 and a surface acoustic wave path 4 through which surface acoustic wave passes. While pressing the surface acoustic wave device 3 to the substrate 5 to make the ring member 10 stick close to the surface acoustic wave device 3 and the substrate 5, the surface acoustic wave device 3 is fixed to the substrate 5 using a connecting member 6 and the tandem type electrode 2 and an external lead-out electrode 8 are electrically connected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device used for a surface acoustic wave filter or the like, and more particularly to a surface mount type elastic surface characterized by a structure for sealing a functional surface of a surface acoustic wave element. The present invention relates to a method of manufacturing a wave device and a surface acoustic wave device.

[0002]

2. Description of the Related Art For example, as shown in FIG. 6, a surface acoustic wave element 23 used in a conventional surface acoustic wave device includes a surface acoustic wave substrate (piezoelectric substrate) 21. It is formed by disposing the comb-teeth electrode (IDT) 22 at a predetermined position on one of the main surfaces. Further, the IDT 2 is provided on both end sides of the surface acoustic wave substrate 21.
An input / output electrode 22a for connecting to 2 is provided. When a voltage is applied to the IDT 22 of the surface acoustic wave element 23, a piezoelectric action causes a strain near the surface of the surface acoustic wave substrate 21, and this strain becomes a surface wave and propagates on the surface.

As described above, the functional surface (vibration surface) 23a of the surface acoustic wave element 23 constituting the surface acoustic wave device, on which the IDT 22 is disposed, is a vibration surface for generating surface waves and is It also functions as the surface wave propagation path 24 for propagating the generated surface wave. Therefore, in order for the surface acoustic wave element 23 to function normally, the principal surface (functional surface) 23a on which the IDT 22 of the surface acoustic wave element 23 is arranged and the surface wave propagation path 24 is formed.
Need not be in contact with other members.

For this reason, there is a surface acoustic wave device in which a surface acoustic wave element is housed in a hermetic case. However, the surface mounting surface acoustic wave device case is made of an expensive monolithic ceramic in order to ensure airtightness. The case is mainly used, which is a factor of increasing the manufacturing cost.

There is also a resin molded product in which the lead portion is exposed to the outside, but the adhesion between the molding resin and the lead portion is not sufficient, and it only withstands the steps of reflow and cleaning. There is a problem that airtightness cannot be secured.

Further, in a surface acoustic wave device which is formed by placing a surface acoustic wave element on a substrate on which wiring is printed, die-bonding and capping, the surface of the substrate is metalized for wire bonding. However, there are problems that the conditions are severe, wire bonding is difficult, the manufacturing process is complicated, and the cost is increased.

Therefore, the inventors of the present invention, as shown in FIG.
We propose a face-down bonding type surface acoustic wave device. In this face-down bonding type surface acoustic wave device, the surface acoustic wave element 23 is
The functional surface 23a having the IDT (not shown) is placed on the substrate 25 in a state of being opposed to the substrate 25 having the external extraction electrode (not shown). The annular member 30 is inserted between the element 23 and the substrate 25 so as to surround the surface wave propagation path through which the IDT and the surface wave propagate, and the surface acoustic wave device 23 is fixed to the substrate 25 by the joining member 26 and is electrically connected. Connected to. In this surface acoustic wave device, the annular member 30 functions as a spacer, forms the vibration space 27 between the functional surface 23a of the surface acoustic wave element 23 and the substrate 25, and the annular member 30 also functions as a partition member. It is possible to prevent foreign matter from entering the vibration space 27 to some extent.

However, in this surface acoustic wave device,
Since the surface acoustic wave element 23 is only placed on the annular member 30, the annular member 30 may have a warp or a non-uniform thickness, and the space between the annular member 30 and the substrate 25 and the annular member 30. It is unavoidable that a certain amount of gap is created between the surface acoustic wave element 23 and the surface acoustic wave element 23, and there is a risk that foreign matter may enter through the gap to deteriorate the characteristics. When the functional surface 23a is to be sealed, there is a problem that the sealing resin enters the vibrating space 27 through the gap.

The present invention solves the above-mentioned problems and surely forms a predetermined vibration space between the functional surface of the surface acoustic wave element and the substrate without requiring a particularly complicated process. It is an object of the present invention to provide a surface acoustic wave device manufacturing method and a surface acoustic wave device that are capable of sealing the functional surface of the surface acoustic wave element from the outside and have excellent sealing performance.

[0010]

In order to achieve the above object, in a method of manufacturing a surface acoustic wave device according to the present invention, a surface acoustic wave element is provided with a functional surface on which a comb-shaped electrode is formed as an external extraction electrode. Is placed on the substrate via an annular member made of an elastic material disposed at a position facing the substrate on which the interdigital electrode and the surface wave propagation path through which the surface wave propagates, and placed on the substrate. While pressing the surface acoustic wave element to bring the annular member into close contact with the surface acoustic wave element and the substrate, the surface acoustic wave element is fixed to the substrate by the joining member, and the comb-shaped electrode and the external extraction electrode are electrically connected. It is characterized by connecting.

Further, in the surface acoustic wave device of the present invention, the surface acoustic wave element is arranged such that the functional surface on which the comb-like electrode is formed faces the substrate on which the external extraction electrode is arranged, and the comb-like electrode is formed. And, it is placed on the substrate through an annular member made of an elastic material arranged at a position surrounding the surface wave propagation path through which the surface wave propagates, and the surface acoustic wave element is pressed to elastically deform the annular member, While being in close contact with the surface acoustic wave element and the substrate, while fixing the surface acoustic wave element to the substrate with a joining member,
It is characterized in that the comb-shaped electrode and the external extraction electrode are electrically connected.

[0012]

According to the method of manufacturing the surface acoustic wave device of the present invention, the comb-shaped electrode formed on the functional surface of the surface acoustic wave element and the annular member arranged so as to surround the surface wave propagation path form the substrate. A space (vibration space) is surely formed between the functional surface of the surface acoustic wave element and the substrate, while the annular member is pressure-bonded to the surface acoustic wave element and the substrate. By bonding and fixing the wave element to the substrate, the sealing performance that seals the vibration space formed between the functional surface of the surface acoustic wave element and the substrate is improved, and when foreign matter enters or resin potting is performed. It is possible to prevent the resin for sealing from entering.

Further, in the surface acoustic wave device of the present invention using the annular member made of an elastic material, the annular member is elastically deformed by being pressed, and the surface acoustic wave device is brought into close contact with the surface acoustic wave device and the substrate. Is fixed to the board,
The sealing performance is improved, and the entry of foreign matter and the resin for sealing when resin potting is more reliably prevented,
The reliability can be improved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a surface acoustic wave device according to an embodiment of the present invention, and FIG. 2 is a plan view showing a surface acoustic wave element that constitutes the surface acoustic wave device of this embodiment.

As shown in FIG. 2, the surface acoustic wave element 3 has
It is formed by disposing a comb-teeth electrode (IDT) 2 at a predetermined position on one main surface of a surface acoustic wave substrate (piezoelectric substrate) 1. Further, on both end sides of the surface acoustic wave substrate 1,
An input / output electrode 2a connected to the IDT 2 is provided.
Then, a part of the functional surface 3a on which the IDT 2 of the surface acoustic wave element 3 is arranged becomes a surface wave propagation path 4 through which the generated surface wave propagates, and a predetermined surface wave is exchanged between the IDTs 2 and 2. Be seen. Further, the functional surface 3 of the surface acoustic wave element 3 is
An annular member 10 is arranged in a so as to surround the IDT 2 and the surface wave propagation path 4. The annular member 10 is
It is made of silicone rubber which is an elastic material, and when it is not pressed, it has a semicircular cross section as shown in FIG. 3, but when it is pressed, as shown in FIG.
It elastically deforms to increase the contact area and improve the sealing performance.

Further, as shown in FIG. 5, the encapsulating substrate (eg, glass-epoxy substrate) 5 arranged so as to face the surface acoustic wave element 3 has external extraction electrodes 8 at the corners, as shown in FIG.
Are formed. The external extraction electrode 8 is formed by subjecting a substrate (unit substrate) to through-hole metallization at predetermined positions (positions at each corner) and then cutting the metal. The method of forming 8 is not limited to this.

Next, a process of manufacturing the surface acoustic wave device by combining the above-mentioned members will be described. First, the surface acoustic wave element 3 in which the annular member 10 made of silicone rubber is disposed on the functional surface 3a is placed on the substrate 5. Then, the surface acoustic wave element 3 is pressed from above with a predetermined pressure to elastically deform the annular member 10 and bring it into close contact with the surface acoustic wave element 3 and the substrate 5. Then, while maintaining this state (that is, a state where the contact area is wide and the surface acoustic wave element 3 and the substrate 5 have high adhesion due to the elastic force), the IDT 2
The input / output electrode 2a that conducts with the external extraction electrode 8 of the substrate 5 is joined by a joining member (solder) 6 to make a predetermined electrical connection, and the surface acoustic wave element 3 is fixed to the substrate 5 (FIG. 1).

In the surface acoustic wave device (FIG. 1) thus formed, the vibrating space 7 is reliably formed between the surface acoustic wave element 3 and the substrate 5, and the vibrating space 7 is
The annular member 10 that is elastically deformed and is in close contact with the surface acoustic wave element 3 and the substrate 5 seals from the outside, and foreign matter does not easily enter in a normal state. In addition, even when resin potting is performed for stronger sealing, the elastically deformed annular member prevents the sealing resin (not shown) from entering the vibrating space 7, Enables reliable hermetic sealing by potting.

By using an annular member made of an elastic material such as silicone rubber as the annular member, the annular member can function as a sound absorbing material, suppress reflected waves, and improve the characteristics. Further, it is also significant in that the manufacturing process can be simplified because it is not necessary to dispose the sound absorbing material in another step. Further, as in the present invention, rather than just placing the annular member on the substrate,
A larger sound absorbing effect can be obtained by arranging the annular member by pressing it with a pressure that elastically deforms to some extent.

In the above embodiment, the case where the annular member is formed by using silicone rubber has been described. However, even when the elastic material is not used (for example, when the epoxy resin annular member is used), a predetermined pressure is applied. By pressing with, it is possible to obtain a considerable adhesion, and it is possible to obtain the desired effect. When an annular member made of an elastic material is used, there is no particular restriction on the kind of the elastic material, and the annular member can be formed using various materials such as synthetic rubber other than silicone rubber.

In the above embodiment, the case where solder is used as the joining member has been described, but in addition, a conductive paste, a conductive adhesive or the like can be used as the joining member.

Further, in the surface acoustic wave device of the above-mentioned embodiment, a lead component can be manufactured by connecting the lead portion to the external extraction electrode.

[0023]

As described above, according to the method of manufacturing the surface acoustic wave device of the present invention, the surface acoustic wave element is placed on the substrate via the annular member, and the surface acoustic wave element is mounted at a predetermined pressure. Since the surface acoustic wave element is connected and fixed to the substrate in a state where the annular member is pressed and brought into close contact, the functional surface of the surface acoustic wave element and the substrate are not required to perform a particularly complicated process. While securing a vibration space with a predetermined thickness between
The functional surface of the surface acoustic wave element can be reliably sealed, and a highly reliable surface acoustic wave device can be manufactured.

Further, the surface acoustic wave device of the present invention uses an annular member made of an elastic material, and presses the elastic member to elastically deform the surface acoustic wave device and the substrate in a state of being in close contact with the surface acoustic wave device. Since it is connected and fixed to, the sealing performance is improved, and it is possible to more reliably prevent the intrusion of foreign matter and the resin for sealing in the case of resin potting, thereby improving the reliability.

[Brief description of drawings]

FIG. 1 is a sectional view showing a surface acoustic wave device according to an embodiment of the present invention.

FIG. 2 is a plan view showing a surface acoustic wave element that constitutes a surface acoustic wave device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing the shape of an annular member used in one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a state in which an annular member used in an embodiment of the present invention is elastically deformed.

FIG. 5 is a plan view showing a substrate that constitutes a surface acoustic wave device according to an embodiment of the present invention.

FIG. 6 is a plan view showing a surface acoustic wave element that constitutes a conventional surface acoustic wave device.

FIG. 7 is a cross-sectional view showing a surface acoustic wave device to which the present invention relates.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Surface acoustic wave substrate 2 Comb-shaped electrode (IDT) 2a Input / output electrode 3 Surface acoustic wave element 3a Functional surface (vibrating surface) 5 Substrate 6 Joining member 7 Vibration space 8 External extraction electrode 10 Annular member

Claims (2)

[Claims] 1. A surface acoustic wave device in which a surface of a surface acoustic wave device having a comb-teeth electrode formed thereon is opposed to a substrate having an external extraction electrode, and the comb-teeth electrode and the surface wave propagate. Placed on a substrate via an annular member made of an elastic material arranged at a position surrounding the path, pressing the surface acoustic wave element to bring the annular member into close contact with the surface acoustic wave element and the substrate,
A method for manufacturing a surface acoustic wave device, comprising fixing a surface acoustic wave element to a substrate with a joining member and electrically connecting a comb tooth-shaped electrode and an external extraction electrode. 2. A surface acoustic wave element in which a surface of a surface acoustic wave element having a comb-teeth electrode formed thereon is opposed to a substrate having an external extraction electrode, and the comb-teeth electrode and the surface wave propagate. It was placed on the substrate through an annular member made of an elastic material arranged at a position surrounding the path, and the surface acoustic wave element was pressed to elastically deform the annular member and brought into close contact with the surface acoustic wave element and the substrate. In the state, the surface acoustic wave device is characterized in that the surface acoustic wave element is fixed to the substrate by the joining member and the comb-shaped electrode and the external extraction electrode are electrically connected.