JPH0563495A - Surface acoustic wave device - Google Patents

Abstract

PURPOSE:To suppress a direct reaching wave component, which is leaked from an input to an output, and to enlarge an attenuated variable in the attenuation area of the surface acoustic wave device by improving the resin package of the surface acoustic wave device. CONSTITUTION:At the surface acoustic wave device composed of a resin mold surrounding equipment 17 provided with a hollow part on the surface of a surface acoustic wave element 6 fixed onto a lead frame 7, a conductive layer 16 is provided on the inside surface of the resin mold surrounding equipment 17 or conductive resin is used for the resin material of the resin mold surrounding equipment 17 or the resin containing resin particles is used, and the conductive layer 16 or the conductive resin is electrically connected to one external terminal 12 of the lead frame 7 at least. Then, an insulating layer 18 is provided to the other external terminal.

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,
In particular, it relates to a packaging method for a surface acoustic wave device.

[0002]

2. Description of the Related Art In recent years, surface acoustic wave devices have become indispensable in electronic equipment utilizing radio waves. On the other hand, however, with the widespread use of electronic devices in consumers, there is a growing demand for lower surface acoustic wave devices.

As one of the methods for lowering the cost, packaging of a surface acoustic wave device using a synthetic resin instead of metal has been considered.

The structure of a conventional surface acoustic wave device package using a synthetic resin will be described with reference to FIG. 4, which is a sectional view thereof.

In FIG. 4, a conventional surface acoustic wave element has a comb-shaped electrode 2 for input and a comb-shaped electrode 3 for output provided on a piezoelectric substrate 1. An insulating resin layer 4 provided by a method such as dipping is provided outside the surface acoustic wave element. Although the surface acoustic wave device configured as described above is inexpensive and highly producible, stray capacitance Cs is generated between the input / output comb-teeth shaped electrodes 2 and 3 through the insulating resin layer 4, and the input is performed through this stray capacitance Cs. Since there are many direct wave components that jump from the comb-shaped electrode to the output comb-shaped electrode,
As a filter, the amount of attenuation in the attenuation region was reduced, impairing the characteristics of the filter.

In order to solve this problem, an improvement proposal whose cross-sectional view is shown in FIG. 5 has already been made (Jpn.
15830).

In FIG. 5, an insulating resin provided by a method such as dipping on the outside of a surface acoustic wave element having a comb-shaped electrode 2 for input and a comb-shaped electrode 3 for output provided on a piezoelectric substrate 1. Layer 4 is provided. A conductive coating 5 that is electrically grounded is provided further outside the insulating resin layer 4.

In this modified example, the stray capacitance Cs between the input / output comb-shaped electrodes 2 and 3 is reduced, and the conductive film is grounded, so that the input comb-shaped electrode 2 outputs the comb-shaped electrode. By absorbing the electric flux passing through 3 to the ground, the direct wave component from the input comb-teeth electrode 2 to the output comb-teeth electrode 3 can be reduced, and the amount of attenuation in the attenuation region of the filter can be secured.

[0009]

However, when the package according to the conventional improved technique of FIG. 5 is used for the surface acoustic wave filter, the attenuation amount of about 35 dB can be secured in the attenuation region of the filter, but the attenuation amount of 40 dB or more can be obtained. It is difficult to realize a filter requiring a large amount even with the package structure according to the conventional improved technique of FIG.

It is an object of the present invention to provide a surface acoustic wave device capable of obtaining a sufficient amount of attenuation in the attenuation range of a device such as a filter by further improving a synthetic resin package.

[0011]

A surface acoustic wave device of the present invention comprising a surface acoustic wave element fixed on a lead frame and a resin mold envelope having a hollow portion on at least an upper surface of the surface acoustic wave element. In the first embodiment, a conductive layer is provided on the inner surface of the hollow portion of the resin mold envelope, by improving the synthetic resin package so that the attenuation amount in the attenuation region of the filter can be increased. It is characterized in that the conductive layer is electrically connected to at least one external terminal of the lead frame, and the other external terminal has an insulating layer formed in the conductive layer penetrating portion of the resin mold.

In the second embodiment, the resin mold envelope is made of a conductive resin, and the conductive resin and at least one external terminal of the lead frame are electrically connected, Another external terminal is characterized in that an insulating layer is formed on the resin mold penetrating portion. Furthermore, the third embodiment is characterized in that the resin mold envelope is formed of a resin containing magnetic powder.

The lead frame used in the surface acoustic wave device of the present invention serves to draw out the terminals of the surface acoustic wave element having the comb-shaped electrodes for input and output to the outside of the resin-molded envelope. Is an iron-nickel alloy (Fe-N
i42 alloy) or a copper-iron alloy (Cu-Fe alloy) that is normally used for semiconductor devices can be used. The surface acoustic wave element is fixed on the lead frame using a silicone adhesive, an epoxy adhesive, a silver paste, a low melting point solder, or the like. Further, the comb-teeth type electrode wiring and the lead frame are electrically connected by a bonding wire such as gold (Au). A thermosetting resin such as an epoxy resin or a thermoplastic resin such as a polyphenylene sulfide resin can be used for the resin mold envelope having a hollow portion on at least the upper surface of the surface acoustic wave element.

The conductive layer formed on the inner surface of the resin mold envelope is coated with a conductive paint or a conductive paste having conductive fine particles such as metal, carbon, a conductive organic substance or an oxide as a binder, and dried. Can be formed.

As the conductive resin, a thermosetting resin such as an epoxy resin or a thermoplastic resin such as a polyphenylene sulfide resin is mixed with conductive fine particles such as metal, carbon, a conductive organic substance or an oxide. Obtainable.

The conductive layer or conductive resin is electrically connected to at least one external terminal of the lead frame, and the remaining other external terminals of the lead frame are connected to the conductive layer or the conductive resin through portion. Forms an insulating layer.

The insulating layer is formed by applying an insulating coating to the lead frame in the portion in contact with the conductive layer or the conductive resin.
Form an insulating film. In addition, an insulating coating is not formed on the lead frame for electrical connection.

The hollow portion of the surface acoustic wave device of the present invention can be manufactured, for example, by the following method.

A volatile substance such as wax or resin that is vaporized at a temperature lower than the softening or deformation temperature of the resin material of the resin mold envelope is applied on the surface acoustic wave element fixed on the lead frame. A porous conductive coating material, a conductive paste, or the like is applied on this, and then a porous resin layer is formed. Porous paints and resins are made by adding fillers and foaming agents. Next, volatile substances such as wax and resin are evaporated through a porous resin material to form a cavity inside the resin mold envelope, and finally, an airtight resin is formed on the surface.

When the resin containing the magnetic powder is used as the resin material of the resin mold envelope, the magnetic powder includes magnetic powder such as ferrite, samarium-cobalt, and neodymium-iron-boron.

When a resin containing magnetic powder is used as the resin material for the resin mold envelope, the magnetic powder is not conductive, so there is no need to insulate the lead frame.

The resin material of the resin mold envelope is
It is also possible to use a conductive resin and a resin containing magnetic powder at least partially at the same time, or to use a conductive resin containing magnetic powder particles.

[0023]

In the first and second embodiments described above,
Use a synthetic resin or conductive resin that has a conductive layer on the inner surface as the resin material of the resin mold envelope, and connect it to the lead terminal that serves as the ground terminal to bring the ground potential as close as possible to the surface acoustic wave element become. Therefore, the direct wave component leaking from the input comb-teeth electrode to the output comb-teeth electrode can be reduced, and the attenuation amount in the attenuation region of the surface acoustic wave device can be increased.

In the third embodiment, the resin containing the magnetic powder is used as the resin material of the resin mold package, so that the entire package can be magnetically shielded. When a conductive layer or conductive resin is used as the resin material of the resin mold package, it is blocked by the conductive coating of the direct wave component that leaks from the input comb-shaped electrode to the output comb-shaped electrode. The component that can be generated is an electrostatic field component, but it is the magnetic field component that can be blocked by the envelope made of resin containing magnetic powder. Generally, a magnetic field component is generated around a lead terminal of a package, a bonding wire, and a high-frequency current flowing through an electric wiring formed on a surface acoustic wave element. Therefore, when resin containing magnetic powder is used as the resin material of the resin mold package, it is effective when the magnetic field component becomes dominant in the direct wave that leaks from the input comb-shaped electrode to the output comb-shaped electrode. Therefore, it is possible to increase the amount of attenuation in the attenuation range of the surface acoustic wave device.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a conductive layer is provided on the inner surface of the resin-molded envelope, and the conductive layer and at least one external terminal of the lead frame are electrically connected, and the other external terminals are the above-mentioned. A perspective view (FIG. 1A) and a cross-sectional view (FIGS. 1B and 1C) of a first embodiment of a surface acoustic wave device of the present invention in which an insulating layer is formed on a conductive layer penetrating portion of a resin mold.
Is.

The first embodiment of the surface acoustic wave device has the following structure.

The surface acoustic wave element 6 is provided with comb-shaped electrodes for input and output on the piezoelectric substrate 1, and is fixedly mounted on a lead frame 7 made of a copper (Cu) alloy. Input / output comb-shaped electrode wiring 8 and shield electrode 9 and lead terminals 10, 11, 12, 1 which are part of the lead frame 7.
3 and 14 are electrically connected to each other by a bonding wire 15 of gold (Au).

As shown in the BB sectional view of FIG. 1 (b),
The surface acoustic wave element 6 is hermetically sealed with a resin mold envelope 17 having a hollow portion whose inner surface is made of a conductive layer 16.

Further, as shown in the sectional view taken along the line AA of FIG. 1C, the lead terminals 10, 11, 1 of the lead frame 7 are shown.
An insulating coating 18 is applied to the portions of the envelopes 3 and 14 that are in contact with the resin material of the envelope 17, and is electrically insulated from the conductive resin 16 applied to the inner surface of the envelope 17. There is. On the other hand, the lead terminal 12 is not coated with the insulating coating 18 and is electrically connected to the conductive resin 16 coated on the inner surface of the envelope 17.

Next, the manufacturing process of the surface acoustic wave device of the first embodiment will be described.

The surface acoustic wave element 6 is mounted on the lead frame 7, and the input / output comb-shaped electrode wiring 8 and the lead terminals 10, 11, 12, 13 on the surface acoustic wave element 6 are bonded by a gold (Au) bonding wire. , 14 are electrically connected (first step).

An insulating coating film 18 is formed on a portion of the lead terminals 10, 11, 13, 14 which is in contact with the resin material of the envelope 17 by a method such as coating an insulating resin material (second).
Process).

The surface acoustic wave element 6 inside the envelope 17.
In order to form a hollow portion around the surface of the envelope 17, the wax that evaporates at a temperature relatively lower than the softening / deformation temperature of the resin material of the envelope 17 is dipped to form the surface acoustic wave element 6
Then, it is applied to the portion of the lead frame 7 where the surface acoustic wave element is mounted (third step).

A porous conductive coating material for forming the conductive layer 16 is applied on the wax by a method such as dipping (fourth step).
Process).

A porous insulating resin material is applied onto the conductive layer 16 by dipping (fifth step).

The wax applied in the third step is evaporated through the porous resin material applied in the fourth and fifth steps to form a cavity inside the envelope 17 (sixth step). Finally, in order to protect the inside of the resin package in an airtight manner, the airtight resin is applied again onto the porous resin material forming the envelope 17 (seventh step).

In the surface acoustic wave device of the first embodiment thus completed, it is possible to reduce the direct wave component leaking from the input comb-teeth electrode to the output comb-teeth electrode, The amount of attenuation in the attenuation range of the surface acoustic wave device could be improved from 35 dB of the conventional example to 40 dB.

Example 2 In FIG. 2, a conductive resin is used as the resin material of the resin mold envelope, and the conductive resin and at least one external terminal of the lead frame are electrically connected to each other. The external terminals of FIG. 2 are a perspective view (FIG. 2A) and a sectional view (FIGS. 2B and 2C) of a second embodiment of a surface acoustic wave device in which an insulating layer is formed on the resin mold penetrating portion. is there. The second embodiment of the surface acoustic wave device has the following configuration.

The surface acoustic wave element 6 is provided with comb-shaped electrodes for input and output on the piezoelectric substrate 1, and is fixedly mounted on a lead frame 7 made of a copper (Cu) alloy. Input / output comb-shaped electrode wiring 8 and shield electrode 9 and lead terminals 10, 11, 12, 1 which are part of the lead frame 7.
3 and 14 are electrically connected by a gold (Au) bonding wire 15.

As shown in the BB cross section of FIG. 2B,
The surface acoustic wave element 6 is sealed with an envelope 17 made of a conductive resin mold having a hollow portion.

Further, as shown in the sectional view taken along line AA of FIG. 2C, the lead terminals 10, 11, 1 of the lead frame 7 are shown.
An insulating film 18 is applied to the portions of the envelopes 3 and 14 that are in contact with the resin material of the envelope 17, and is electrically insulated from the conductive resin forming the envelope 17. On the other hand, the insulating coating 18 is not applied to the lead terminals 12 and is electrically connected to the conductive resin forming the envelope 17.

Next, the manufacturing process of the surface acoustic wave device of the second embodiment will be described.

The surface acoustic wave element 6 is mounted on the lead frame 7, and the input / output comb-shaped electrode wiring 8 and the lead terminals 10, 11, 12, 13 on the surface acoustic wave element 6 are bonded by a gold (Au) bonding wire. , 14 are electrically connected (first step).

An insulating coating film 18 is formed on a portion of the lead terminals 10, 11, 13, 14 which is in contact with the resin material of the envelope 17 by a method such as applying an insulating resin material (second step). ..

The surface acoustic wave device 6 inside the envelope 17.
In order to form a hollow portion around the surface of the envelope 17, the wax that evaporates at a temperature relatively lower than the softening / deformation temperature of the resin material of the envelope 17 is dipped to form the surface acoustic wave element 6
Then, it is applied to the portion of the lead frame 7 where the surface acoustic wave element is mounted (third step).

A porous conductive resin is applied onto the wax by a method such as dipping to form the envelope 17 (fourth step).

The wax applied in the third step is evaporated through the porous resin material applied in the fourth step to provide a cavity inside the envelope 17 (fifth step).

Finally, in order to protect the inside of the resin package in an airtight manner, the airtight resin is applied once again on the porous conductive resin forming the envelope 17 (sixth step).

In the surface acoustic wave device of the second embodiment thus completed, it is possible to reduce the direct wave component leaking from the input comb-teeth electrode to the output comb-teeth electrode, The amount of attenuation in the attenuation range of the surface acoustic wave device could be improved from 35 dB of the conventional example to 40 dB.

FIG. 3 is a perspective view (FIG. 3 (a)) and a cross section of a third embodiment of the surface acoustic wave device of the present invention in which a resin containing magnetic powder is used as the resin material of the resin mold envelope. It is a figure (FIG.3 (b), (c)).

The first embodiment of the surface acoustic wave device has the following structure.

The surface acoustic wave element 6 is provided with comb-shaped electrodes for input and output on the piezoelectric substrate 1, and is fixedly mounted on a lead frame 7 made of a copper (Cu) alloy. Input / output comb-shaped electrode wiring 8 and shield electrode 9 and lead terminals 10, 11, 12, 1 which are part of the lead frame 7.
3 and 14 are electrically connected by a gold (Au) bonding wire 15.

As shown in the BB cross section of FIG. 3B,
The surface acoustic wave element 6 is sealed with an envelope 17 made of a resin mold containing magnetic powder having a hollow portion.

Further, as shown in the sectional view taken along the line AA of FIG. 3C, the lead terminals 10, 11, 1 of the lead frame 7 are shown.
No insulating coating is applied to the portions where 2, 13, and 14 are in contact with the resin material of the envelope 17.

Next, the manufacturing process of the surface acoustic wave device of the third embodiment will be described.

The surface acoustic wave element 6 is mounted on the lead frame 7, and the input / output comb-shaped electrode wiring 8 and the lead terminals 10, 11, 12, 13 on the surface acoustic wave element 6 are bonded by a gold (Au) bonding wire. , 14 are electrically connected (first step).

The surface acoustic wave device 6 inside the envelope 17.
In order to form a hollow portion around the surface of the envelope 17, the wax that evaporates at a temperature relatively lower than the softening / deformation temperature of the resin material of the envelope 17 is dipped to form the surface acoustic wave element 6
Then, it is applied to the portion of the lead frame 7 where the surface acoustic wave element is mounted (second step).

A resin containing porous magnetic powder is applied onto the wax by a method such as dipping to form the envelope 17 (third step).

The wax applied in the second step is evaporated through the porous resin material applied in the third step to provide a cavity inside the envelope 17 (fourth step).

Finally, in order to protect the inside of the resin package in an airtight manner, the airtight resin is applied once again on the porous conductive resin forming the envelope 17 (fifth step).

In the surface acoustic wave device of the third embodiment thus completed, the direct wave component in which the magnetic field component leaking from the input comb-shaped electrode to the output comb-shaped electrode becomes dominant. Could be reduced.

[0063]

According to the surface acoustic wave device of the present invention, a conductive layer is provided on the inner surface of the resin mold envelope, or a conductive resin is used for the resin mold envelope, and the conductive layer or the conductive layer is used. Conductive resin and at least one external terminal of the lead frame are electrically connected, and the other external terminal has a conductive layer of the resin mold or an insulating layer formed on the conductive resin penetrating portion, or a resin mold Since the resin containing magnetic powder is used as the resin material of the envelope, the direct wave component leaking from the input to the output of the surface acoustic wave device can be suppressed, and the amount of attenuation in the attenuation region of the surface acoustic wave device can be increased. This enables the performance of the surface acoustic wave device.

[Brief description of drawings]

FIG. 1 is a perspective view of a surface acoustic wave device according to a first embodiment (a).
And a cross-sectional view (b) taken along the line BB in FIG.
It is sectional drawing (c) which follows the AA line of (a).

FIG. 2 is a perspective view of a surface acoustic wave device according to a second embodiment (a).
2B is a cross-sectional view taken along line BB of FIG.
It is sectional drawing (c) which follows the AA line of (a).

FIG. 3 is a perspective view of a surface acoustic wave device according to a third embodiment (a).
And a cross-sectional view (b) taken along the line BB of FIG.
It is sectional drawing (c) which follows the AA line of (a).

FIG. 4 is a cross-sectional view for explaining a conventional surface acoustic wave device.

FIG. 5 is a cross-sectional view for explaining a conventional surface acoustic wave device.

[Explanation of symbols]

1 ... Piezoelectric substrate, 2 ... Input comb-shaped electrode, 3 ...
Input / output comb-shaped electrodes, 4 ... Insulating resin layer, 5 ... Conductive film, 6 ... Surface acoustic wave element, 7 ... Lead frame, 8 ... Input / output comb-shaped electrode wiring, 9 ...... Shield electrodes, 10, 11, 12, 13, and 14 ... Lead terminals, 15 ... Bonding wires, 16 ... Conductive layer, 1
7 ... Resin mold envelope, 18 ... Insulating film.

Claims (3)

[Claims] 1. A surface acoustic wave device comprising a surface acoustic wave element fixed on a lead frame and a resin mold envelope having a hollow portion on at least an upper surface of the surface acoustic wave element. A conductive layer is provided on the inner surface of the hollow portion, and the conductive layer and at least one external terminal of the lead frame are electrically connected, and the other external terminal forms an insulating layer in the conductive layer penetrating portion of the resin mold. A surface acoustic wave device characterized by the above. 2. A surface acoustic wave device comprising a surface acoustic wave element fixed on a lead frame and a resin mold envelope having a hollow portion on at least an upper surface of the surface acoustic wave element. Is formed of a conductive resin, the conductive resin is electrically connected to at least one external terminal of the lead frame, and the other external terminal is formed with an insulating layer in the resin mold penetrating portion. And surface acoustic wave device. 3. A surface acoustic wave device comprising a surface acoustic wave element fixed on a lead frame and a resin mold envelope having a hollow portion on at least an upper surface of the surface acoustic wave element. A surface acoustic wave device, wherein the surface acoustic wave device is formed of a resin containing magnetic powder.