JPH0378263A - Surface acoustic wave device package - Google Patents

Abstract

PURPOSE:To make very small interearth capacitance between a comb-shaped electrode and a bonding pad of a surface acoustic wave device, and a metal stem by forming with a non-metallic member a portion of the stem with which the surface acoustic wave device makes close contact. CONSTITUTION:The whole of a portion of a stem 5 with which the back surface of a surface acoustic wave device 1 makes close contact is so blanked that it penetrates the stem 5, and the hole is filled with a non-metallic member 9. The device 1 is fixedly placed on the non-metallic member 9, and a bonding pad 4 and a terminal pin 7 are wire-bonded through a metal fine line 8. With such arrangement, interearth capacitance between the thin film comb-shaped electrode 3 and the pad 4 of the device 1 and the metal stem 5 is made very small and negligible on circuit design.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a surface acoustic wave device package used for a surface acoustic wave device filter, a surface acoustic wave device resonator, etc. The present invention relates to a surface acoustic wave device package suitable for improving performance.

[Prior Art] Surface acoustic wave device packages are recently frequently used in filters, resonators, etc., for example, in cellular type portable wireless communication devices. Then, the back side of the surface acoustic wave element is placed and glued on a metal stem having terminal pins for connection, and packaged.
No. 1311 discloses this type of surface acoustic wave device package (mounting structure for a surface acoustic wave device).

8 to 10 are views showing conventional surface acoustic wave device packages of this type, with FIG. 8 being an exploded perspective view thereof, FIG. 9 being a sectional view of the surface acoustic wave device package, and FIG. This is an enlarged view of the main part of FIG. 9.

In each episode, 1 is a surface acoustic wave element, which includes a piezoelectric substrate 2 made of, for example, lithium tantalate, lithium niobate, etc., and a thin film comb-shaped electrode 3 formed on the piezoelectric substrate 2.
and a bonding pad (connection electrode) 4. 5
is a metal stem, and includes a metal terminal pin 7 that is partially embedded in the stem 5 through a glass resin 6. Then, the back surface of the surface acoustic wave element 1 is fixed to the upper surface (adhesive surface) 5a of the stem 5 with an appropriate adhesive, and the bonding pad 4 and the terminal pin 6 are attached to the thin metal wire 8 (for example, an Au wire). ) is wire bonded.

The surface acoustic wave device package having the above structure is mounted on, for example, a printed wiring board (not shown), and the terminal pins 6 are connected to a conductive pattern formed on one surface of the printed wiring board. At this time, the bottom surface of the stem 5 is closely connected to the ground pattern formed on the other surface of the printed wiring board, and earthing (shielding) measures are taken to stabilize and improve high frequency characteristics. It has become.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, consideration is not given to the ground capacitance between the thin film comb-shaped electrode 3 and the bonding pad 4 of the surface acoustic wave element 1 and the metal stem 5. It had not been done. That is, the adhesive surface 5a of the stem 5
are all metal surfaces, so there is a ground capacitance (stray capacitance: 5tray e
apacit, y) Cs occurs, and this ground capacitance Cs
There has been a problem in that the surface acoustic wave device packages shown in FIGS. 8 to 10 cannot be used for surface acoustic wave devices for applications in which circuit design does not require the following. Further, even when the ground capacitance Cs is incorporated as a design parameter of a surface acoustic wave device, there is a problem that it is difficult to adjust the capacitance, and as a whole, the degree of freedom in device design is greatly hindered.

The present invention has been made in view of the above points, and its purpose is to make it possible to control the ground-to-ground capacitance on the package side, and to reduce this capacitance to a level that can be practically ignored in locations where no ground-to-ground capacitance is required. can be reduced as much as possible,
An object of the present invention is to provide a surface acoustic wave device package (mounting structure for a surface acoustic wave device) that can increase the degree of freedom in device design.

[Means for Solving the Problems] In order to achieve the above-mentioned objects, the present invention provides a surface acoustic wave device including a thin film comb-shaped electrode provided on a piezoelectric substrate, and a surface acoustic wave device on which a back surface portion of the surface acoustic wave device is mounted. In a surface acoustic wave device package including a metal stem to be bonded, a portion of the stem to which the surface acoustic wave device is in close contact is made of a non-metallic material, or a portion of the stem to which the surface acoustic wave device is in close contact is made of a non-metallic material. Among the parts that do not require ground-to-ground capacitance (stray capacitance), only those parts are made of non-metallic material.

[Function] As mentioned above, the adhesive part of the surface acoustic wave element is attached to a non-metallic material,
For example, if a stem made of glass resin is used, the metal part of the stem (
The stray capacitance (ground capacitance) of the main body of the stem can be made as small as possible (so small that it can be ignored in practical terms), and the degree of freedom in element design increases.

[Example code] The present invention will be described below with reference to illustrated embodiments.

1 to 3 relate to a surface acoustic wave device package according to a first embodiment of the present invention, in which FIG. 1 is an exploded perspective view, FIG. 2 is a sectional view of the surface acoustic wave device package, and FIG. 3 is a cross-sectional view of the surface acoustic wave device package. This is an enlarged view of the main parts of Figure 2. In each episode, 1 is a surface acoustic wave element and 2 is a piezoelectric substrate.

3 is a thin film comb-shaped electrode, 4 is a bonding pad, 5 is a metal stem, 6 is a glass resin, 7 is a terminal pin, and 8 is a thin metal wire (Hondaig Tsuya), which correspond to the conventional configuration described above. The explanation is omitted to avoid duplication.

In this first embodiment, the entire portion of the stem 5 that is in close contact with the back surface of the surface acoustic wave element 1 (the back surface of the piezoelectric substrate 2) is extracted so as to penetrate through the stem 5, and is filled with a non-metallic material 9 instead. It is. The material of this non-metallic material 9 is arbitrary, but in this embodiment, glass resin 6 for embedding the terminal pin 7 is used in consideration of productivity. Then, the surface acoustic wave element 1 is placed on the non-metallic material 9 and fixed with an appropriate adhesive, and the bonding pad 4 and the terminal pin 7 are wire-bonded using the thin metal wire 8. It has become.

In this embodiment having such a configuration, as shown in FIG. The capacitance) Cs' is extremely small and can be ignored in terms of circuit design. Therefore, it becomes possible to construct a surface acoustic wave element package that is not restricted by stray capacitance and a circuit using the same, and the degree of freedom in design is greatly improved.

4 and 5 relate to the second embodiment of the present invention, and FIG.
The figure is an explanatory diagram showing the surface acoustic wave element 1 and the stem 5 disassembled and viewed from the top, and FIG. 5 shows the surface acoustic wave element 1 and the stem 5.
FIG. 5 is a sectional view taken along the line A-A in FIG. 4 in a state where the device is mounted on the device; In this second embodiment, a portion of the region S (the region hatched with dotted lines in the figure) in which the surface acoustic wave element 1 is in close contact with the stem 5 is made of the non-metallic material 9. In this embodiment having such a configuration, the thin film comb-shaped electrode 3 which requires a ground capacitance between the stem 5 and the
A surface acoustic wave device package can be manufactured in which A and the thin film comb-shaped electrode 3B, which does not require a ground-to-ground capacitance, are mixed on the same stem 5, and the degree of freedom in design is greatly increased.

6 and 7 relate to the third embodiment of the present invention, and FIG.
The figure is a perspective view of the stem 5, and FIG. 7 is a sectional view of the stem 5. In this third embodiment, although the portion of the stem 5 that the surface acoustic wave element 1 is in close contact with is made of a non-metallic material 9, by adjusting the thickness t of the non-metallic material 9, the thin film comb-shaped electrode 3
Also, the distance to the metal surface of the stem 5 facing the bonding pad 4 can be variably set. According to this embodiment having such a configuration, the ground capacitance (stray capacitance) between the thin film comb-shaped electrode 3 and the bonding pad 4 and the metal stem 5 can be set to a desired value required for circuit design. Can be set.

[Effects of the Invention] As described above, according to the present invention, the ground capacitance (stray capacitance) between the thin film comb-shaped electrode and the bonding pad of the surface acoustic wave element and the metal stem can be easily adjusted, and the ground capacitance (stray capacitance) can be easily adjusted. For devices that do not require intermediate capacitance, this capacitance can be reduced as much as possible to the point where it can be ignored in practical terms, thereby greatly increasing the degree of freedom in element design of a single surface acoustic wave element and circuit design using this element. In addition, the accuracy of circuit operation is also improved.

[Brief explanation of drawings]

1 to 3 relate to a surface acoustic wave device package according to an embodiment of the present invention, FIG. 1 is an exploded perspective view thereof, FIG. 2 is a sectional view of the surface acoustic wave device package, and FIG. 2, and FIGS. 4 and 5 relate to the second embodiment of the present invention. FIG. 5 is a cross-sectional view taken along the line A-A in FIG. 4 in a state in which the surface acoustic wave element is mounted on the stem, FIGS. 6 and 7 relate to the third embodiment of the present invention, and FIG. 6 is a perspective view of the stem. Figure 7 is a sectional view of the stem, Figure 8 is a cross-sectional view of the stem.
Figures to Figures 10 relate to conventional surface acoustic wave device packages, where Figure 8 is an exploded perspective view thereof, Figure 9 is a sectional view of the surface acoustic wave element package, and Figure 10 is an enlarged view of the main part of Figure 9. It is a diagram. 1...Surface acoustic wave element, 2...Piezoelectric substrate, 3°3A, 3B...Thin film comb-shaped electrode, 4...
...Ponding pad, 5...Stem,
6...Glass resin, 7...Terminal pin,
G... Thin metal wire (bonding wire), 9.
...Non-metallic material. Figure 6 Figure 7 Figure 1O Figure

Claims (3)

[Claims] 1. A surface acoustic wave device package comprising a surface acoustic wave device having thin film comb-shaped electrodes provided on a piezoelectric substrate, and a metal stem on which a back surface portion of the surface acoustic wave device is placed and bonded. A surface acoustic wave device package, characterized in that a portion to which the surface acoustic wave device is in close contact is made of a non-metallic material. 2. A surface acoustic wave device package comprising a surface acoustic wave device having thin film comb-shaped electrodes provided on a piezoelectric substrate, and a metal stem on which a back surface portion of the surface acoustic wave device is placed and bonded. A surface acoustic wave device package characterized in that, of the portions to which the surface acoustic wave device is in close contact, only those portions that do not require ground-to-ground capacitance (stray capacitance) are made of non-metallic material. 3. 3. The surface acoustic wave device package according to claim 1, wherein the thickness of the non-metallic material disposed at a portion of the stem where the surface acoustic wave device is in close contact can be variably set.