JP2005236475A - Surface acoustic wave device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface acoustic wave device wherein no metallic particles adhere to the surface of a surface acoustic wave element, even if sparks are produced in a process of welding a metallic lid to a base for configuring a package. <P>SOLUTION: The surface acoustic wave accommodates the surface acoustic wave element 1 in the inside of the package 2, and the package 2 comprises a ceramic base 21 recessed with a cavity 20 to accommodate the surface acoustic wave element 1; and a metallic lid 22 welded and fixed to an opening edge of the ceramic base 21, while covering the cavity 20. A resin wall 5 for enclosing the entire circumference of the containing space of the surface acoustic wave element 1 is interposed between the metallic lid 22 and the ceramic base 21, configuring the package 2 along the inside of the welded and fixed part between the both. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface acoustic wave device configured by housing a surface acoustic wave element in a package, such as a surface acoustic wave filter and a surface acoustic wave resonator, which are equipped in various electronic devices, and a method for manufacturing the same.

  A surface acoustic wave device, for example, a surface acoustic wave filter, includes a surface acoustic wave element (1) inside a package (9) as shown in FIG. 5, and the package (9) is composed of a surface acoustic wave element (1). A ceramic base (91) having a cavity (90) for receiving a cavity, and a metal lid (92) covering the cavity (90) and welded to the opening edge of the ceramic base (91). (See Patent Document 1).

For example, as shown in FIG. 6, the surface acoustic wave element (1) is formed with an IDT (12) composed of a pair of hook-shaped electrodes on the surface of a piezoelectric substrate (11) and reflectors on both sides of the IDT (12). (13) (13) is formed, and the IDT (12) is formed with an electrode pitch λ of several μm, for example.
The IDT (12) on the piezoelectric substrate (11) is connected to a pad portion (93) provided on the ceramic substrate (91) via a wire (3) as shown in FIG.
In the surface acoustic wave element (1), when an electric signal is input to one electrode of the IDT (12), a surface acoustic wave is excited on the surface of the piezoelectric substrate (11), and the surface acoustic wave is transmitted to the piezoelectric substrate (11). ) Is transmitted to the other electrode, and an electric signal is output from the electrode.

FIG. 7 shows a manufacturing process of the surface acoustic wave device.
First, as shown in FIG. 7 (a), a ceramic substrate (91) is prepared in which a cavity (90) is recessed on the surface and a metal seam ring (94) is fixed surrounding the cavity (90). Then, the surface acoustic wave element (1) is placed on the bottom surface of the cavity (90) of the ceramic substrate (91) with the electrode formation surface (14) facing upward.
Next, as shown in FIG. 7B, each electrode of the surface acoustic wave element (1) and the pad portion of the ceramic substrate (91) are connected to each other by a wire (3).
Finally, as shown in FIG. 7 (c), the metal lid (92) is seam welded to the opening edge of the ceramic base (91) via the seam ring (94) to seal the cavity (90).
JP-A-9-294044 (FIG. 6)

  In the conventional surface acoustic wave device shown in FIGS. 5 to 7, a spark is generated in the process of seam welding the metal lid (92) to the opening edge of the ceramic substrate (91), and the molten metal is a fine micrometer having a diameter of several μm. There was a possibility that the particles would be attached to the surface of the surface acoustic wave device (1). For example, as shown by a broken line in FIG. 6, when the metal particle (10) adheres across two electrodes of the IDT (12), a short circuit occurs between both electrodes.

In particular, surface acoustic wave filters and surface acoustic wave resonators used in in-vehicle electronic devices such as remote keyless entry systems and tire pressure monitoring systems and mobile phones require a very low defect occurrence rate. The adhesion of metal particles to the element surface accompanying the generation becomes a big problem.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a surface acoustic wave device in which metal particles do not adhere to the element surface even if a spark is generated in the process of welding a metal lid to a substrate constituting a package, and a method for manufacturing the same. It is.

The surface acoustic wave device according to the present invention accommodates a surface acoustic wave element (1) inside a package (2) having a sealed structure, and the package (2) accommodates the surface acoustic wave element (1). A base body (21) having a cavity (20) for recessing and a metal lid (22) covering the cavity (20) and welded to the opening edge of the base body (21).
Between the base (21) and the metal lid (22) constituting the package (2), the entire circumference of the accommodation space of the surface acoustic wave element (1) is surrounded along the inner side of the weld fixing part between the two. The resin wall (5) is interposed, and is in close contact with the base (21) and the metal lid (22).

  In a specific configuration, the base body (21) constituting the package (2) is made of ceramic, and at least an opening edge to which the metal lid (22) is to be fixed by welding is covered with a metal layer. On the other hand, the metal lid (22) is seam welded.

The surface acoustic wave device of the present invention is manufactured by the following manufacturing method.
First, in the first step, the surface acoustic wave element (1), a base body (21) in which a cavity (20) for accommodating the surface acoustic wave element (1) is recessed, and the cavity (20) are covered. Thus, a metal lid (22) to be welded and fixed to the opening edge of the base body (21) is produced.
In the second step, the surface acoustic wave element (1) is placed on the bottom surface of the cavity (20) of the base body (21).
In the third step, a resin wall (5) surrounding the entire circumference of the cavity (20) is formed on the surface of the base body (21) along the inner side of the welding region where the metal lid (22) is to be welded.
In the fourth step, the outer peripheral portion of the metal lid (22) is brought into close contact with the surface of the welding region of the base (21) and the resin wall (5), and the metal lid (22) is set on the base (21).
Finally, in the fifth step, the outer peripheral portion of the metal lid (22) is seam welded to the welding region of the base (21).

  According to the method for manufacturing the surface acoustic wave device, the resin wall (5) is placed on the base (21) and the metal lid (22) by installing the metal lid (22) on the base (21) in the fourth step. Close contact with. Therefore, even when a spark is generated when the metal lid (22) is seam welded to the base (21) in the fifth step, the resin wall (5) is formed along the inside of the welded portion. The molten metal particles are received by the resin wall (5) and do not adhere to the surface of the surface acoustic wave element (1).

For example, the resin wall (5) is made of a thermoplastic resin, and in the third step, the resin wall (5) is formed at a height at which the surface of the resin wall (5) protrudes from the welding region of the base (21). In the fourth step, the resin wall (5) is heat-treated with the metal lid (22) installed on the base (21). As a result, the resin wall (5) is once melted, and the surface of the resin wall (5) is flush with the welding region of the base (21) and is in close contact with the back surface of the metal lid (22). It will solidify.
As a result, the scattering of the molten metal particles generated with the welding in the fifth step is completely prevented by the resin wall (5).

  According to the surface acoustic wave device and the method for manufacturing the same according to the present invention, even if a spark is generated in the process of welding the metal lid to the base body, metal particles do not adhere to the element surface, so that a high yield can be obtained. At the same time, the incidence of defects in the market is greatly reduced.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
As shown in FIG. 1, a surface acoustic wave device according to the present invention comprises a package (2) having a sealed structure formed by seam welding a metal lid (22) to an opening edge of a rectangular parallelepiped ceramic base (21). The surface acoustic wave element (1) is accommodated in the package (2).

As shown in FIG. 2, a cavity (20) for accommodating the surface acoustic wave element (1) is recessed on the surface of the ceramic substrate (21), and the surface acoustic wave element (1) is formed on the bottom surface of the cavity (20). ), And each electrode (not shown) of the surface acoustic wave element (1) is connected to a pad portion (not shown) provided on the ceramic substrate (21) via a wire (3).
A metal lid (22) is seam welded to the opening edge of the ceramic substrate (21) through a seam ring (23) having a thickness of, for example, 200 to 300 μm. In addition, an epoxy or silicon resin wall surrounding the entire circumference of the accommodation space of the surface acoustic wave element (1) along the inner peripheral surface of the seam ring (23) is provided at the opening edge of the ceramic base (21). (5) is formed, and the surface thereof is in close contact with the back surface of the metal lid (22).

FIG. 3 shows a manufacturing process of the surface acoustic wave device of the present invention.
First, as shown in FIG. 3 (a), a ceramic substrate (21) having a cavity (20) recessed on the surface and surrounding the cavity (20) to which a seam ring (23) is fixed is prepared. The surface acoustic wave element (1) is placed on the bottom surface of the cavity (20) with the electrode formation surface (14) facing upward.
Next, as shown in FIG. 3 (b), the electrodes of the surface acoustic wave element (1) and the pads of the ceramic substrate (21) are connected to each other by wires (3), and then the ceramic as shown in FIG. 3 (c). A resin wall is filled on the opening edge of the base body (21) along the inner peripheral surface of the seam ring (23) to surround the entire circumference of the accommodation space of the surface acoustic wave element (1). 5) is formed. Here, the resin wall (5) is formed at a height such that its surface slightly protrudes from the surface of the seam ring (23).

Thereafter, as shown in FIG. 3 (d), the metal lid (22) is pressed against the surface of the resin wall (5), the metal lid (22) is placed on the seam ring (23), and the resin wall (5) is heated. Apply processing. As a result, the resin wall (5) is once melted and solidified in a state where the surface thereof is in close contact with the back surface of the metal lid (22).
Finally, as shown in FIG. 3 (e), the metal lid (22) is seam welded to the opening edge of the ceramic substrate (21) via the seam ring (23) to seal the inside of the package (2).

In the above manufacturing process, when the metal lid (22) is seam welded to the opening edge of the ceramic substrate (21) via the seam ring (23) as shown in FIG. Even if scattered, the metal particles are received by the resin wall (5), and therefore do not adhere to the surface of the surface acoustic wave element (1).
Therefore, according to the surface acoustic wave device of the present invention, there is no possibility that a short circuit occurs due to adhesion of metal particles between the pair of electrodes constituting the IDT (12), and a higher yield than the conventional one can be obtained.

In the surface acoustic wave device according to the present invention, as a method of welding and fixing the metal lid (22) to the ceramic substrate (21), it is possible to employ direct seam welding without using a seam ring, and direct seam welding. An example of the manufacturing method which employ | adopted is shown to Fig.4 (a)-(e).
As shown in FIG. 4 (a), a ceramic substrate (21) having a cavity (20) formed on the surface and a peripheral wall portion (25) surrounding the cavity (20) is prepared. A metal plating layer is formed on the surface of the peripheral wall portion (25) of the base body (21). Then, the surface acoustic wave element (1) is installed on the bottom surface of the cavity (20) with the electrode formation surface (14) facing upward.
Next, as shown in FIG. 4 (b), each electrode of the surface acoustic wave element (1) and each pad portion of the ceramic substrate (21) are connected to each other by a wire (3), and then the ceramic as shown in FIG. 4 (c). A resin wall is filled on the opening edge of the base body (21) along the inner peripheral surface of the peripheral wall portion (25) to surround the entire circumference of the accommodation space of the surface acoustic wave element (1). 5) is formed.

After that, as shown in FIG. 4 (d), the metal lid (22) is pressed against the surface of the resin wall (5), and the metal lid (22) is placed on the peripheral wall portion (25) of the ceramic base (21). The wall (5) is heated. As a result, the resin wall (5) is once melted and solidified in a state where the surface thereof is in close contact with the back surface of the metal lid (22).
Finally, as shown in FIG. 4E, a metal lid (22) is seam welded to the peripheral wall portion (25) of the ceramic substrate (21) to seal the inside of the package (2).

  In the above manufacturing process, even when a metal lid (22) is seam welded to the peripheral wall (25) of the ceramic substrate (21) as shown in FIG. Since the metal particles are received by the resin wall (5), they do not adhere to the surface of the surface acoustic wave element (1).

  In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim. For example, the resin wall (5) is not limited to one produced by heat-treating a thermoplastic resin, and is formed by a resin molded product having elasticity, and is configured to be crimped to the back surface of the metal lid (22) by its elastic restoring force. Can also be adopted.

It is a perspective view in the state where the metal lid of the surface acoustic wave device concerning the present invention was removed. 1 is a cross-sectional view of a surface acoustic wave device according to the present invention. It is process drawing which shows the manufacturing method of the surface acoustic wave apparatus which concerns on this invention. It is process drawing which shows the other manufacturing method of the surface acoustic wave apparatus which concerns on this invention. It is a perspective view of the state which removed the metal cover of the conventional surface acoustic wave apparatus. It is an enlarged plan view of a surface acoustic wave element. It is process drawing which shows the manufacturing method of the conventional surface acoustic wave apparatus.

Explanation of symbols

(1) Surface acoustic wave device
(2) Package
(20) Cavity
(21) Ceramic substrate
(22) Metal lid
(23) Seam ring
(25) Perimeter wall
(3) Wire
(5) Resin wall

Claims (5)

  The surface acoustic wave element (1) is accommodated in the package (2) having a sealed structure, and the package (2) has a cavity (20) for accommodating the surface acoustic wave element (1). The surface acoustic wave device comprises a substrate (21) and a metal lid (22) welded and fixed to the opening edge of the substrate (21) so as to cover the cavity (20). Between the base body (21) and the metal lid (22), there is a resin wall (5) surrounding the entire circumference of the accommodation space of the surface acoustic wave element (1) along the inside of the weld fixing part between them. A surface acoustic wave device that is interposed and is in close contact with a substrate (21) and a metal lid (22).   The substrate (21) constituting the package (2) is made of ceramic, and at least the opening edge to which the metal lid (22) is to be fixed by welding is covered with a metal layer. The surface acoustic wave device according to claim 1, wherein 22) is seam welded. In a method for manufacturing a surface acoustic wave device in which a surface acoustic wave element (1) is housed inside a package (2) having a sealed structure,
A surface acoustic wave element (1), a base body (21) in which a cavity (20) for accommodating the surface acoustic wave element (1) is recessed, and an opening of the base body (21) covering the cavity (20) A first step of producing a metal lid (22) to be welded to the edge;
A second step of installing the surface acoustic wave element (1) on the bottom surface of the cavity (20) of the substrate (21);
A third step of forming, on the surface of the base body (21), a resin wall (5) surrounding the entire circumference of the cavity (20) along the inner side of the welding region to which the metal lid (22) is to be welded;
A fourth step of placing the metal lid (22) on the base (21) by bringing the outer periphery of the metal lid (22) into close contact with the weld region of the base (21) and the surface of the resin wall (5);
And a fifth step of seam welding the outer peripheral portion of the metal lid (22) to the weld region of the base (21).   In the third step, the resin wall (5) is formed at a height at which the surface of the resin wall (5) protrudes from the welding region of the base (21). In the fourth step, the metal lid (22) is formed. The method for manufacturing a surface acoustic wave device according to claim 3, wherein the surface of the resin wall (5) is arranged at the same height as the welding region of the substrate (21) by installation. The method of manufacturing a surface acoustic wave device according to claim 4, wherein the resin wall (5) is made of a thermoplastic resin, and in the fourth step, the resin wall (5) is melted by heat treatment.

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