JPH07111438A - Surface acoustic wave device and its production - Google Patents

Abstract

PURPOSE:To manufacture the surface acoustic wave(SAW) device without use of a special equipment while troublesome processing process is eliminated in the manufacture process of the SAW device. CONSTITUTION:A surface 12 of a SAW element 10 and a surface 22 of a package board 20 are opposed to each other. A bump 17 made of a conductor material is interposed between electrode pads 15, 25a of the both so that a space S is formed between an interdigital electrode 14 formed on the surface 12 of the SAW element 10 and the surface 22 of the package board 20 and the electrode pads 15, 25a of the both are connected mutually electrically. A side circumference of the space S is covered by an adhesives 30 including metallic particles so as to shield the space from an external space. The outer surface of the adhesives 30 including metallic particles is covered by a solder material 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a surface acoustic wave (hereinafter referred to as SAW) element having a crossed finger electrode formed on a piezoelectric substrate, and a package substrate on which the SAW element is mounted. SAW device.

[0002]

2. Description of the Related Art Portable radio terminals such as car phones and cordless phones are in the trend of miniaturization and weight reduction, and in order to realize this, miniaturization and planar mounting of parts used are being promoted.

Among such used parts, the SAW device, which is widely used in the high-frequency circuit section, has been improved from the can-sealing type with lead pin to the box type as shown in FIG. 9 and put into practical use. This SAW device includes a SAW element 1, a package substrate 5 on which the SAW element 1 is mounted, a metal frame and a metal lid for covering the SAW element 1.
In the SAW element 1, a cross finger electrode 3, a signal electrode 3a, a ground electrode 3b, and the like are formed on a piezoelectric crystal substrate 2 made of LiTaO ₃ , LiNbO _3, or the like. The SAW element 1 is made to face the back surface (the surface on the side where the crossed finger electrodes are not formed) and the surface of the package substrate 5 made of ceramic such as alumina so as to form a die bond material 7 such as an epoxy adhesive. And is fixed on the package substrate 5. The signal electrode 3a and the ground electrode 3b of the SAW element 1 are connected to the element-side signal electrode 6a and the element-side ground electrode 6b formed on the package substrate 5 by bonding wires 4 and 4, respectively. The package substrate 5 has NiF beforehand.
A metal frame 8 made of an e-based alloy is fixed with silver solder. The SAW element 1 is sealed on the upper surface of the metal frame 8 by seam welding a metal lid 9 also made of NiFe alloy. That is, in the SAW device, the interdigital electrodes 3 of the SAW element 1 are in contact with the free space S in order to prevent the surface acoustic wave from being attenuated in order to ensure its function, and at the same time, the SAW element 1 is completely protected in order to maintain reliability. The structure must be hermetically sealed.

By the way, recently, in order to further reduce the size of the SAW device, for example, Japanese Unexamined Patent Publication No. 4-293310.
Those described in Japanese Patent Laid-Open No. 186662/1990 and the like are reported. These are all SA
The surface of the W element (the surface on which the cross finger electrodes are formed)
And the surface of the package substrate are opposed to each other, the two are connected so as to form a constant space therebetween, and the periphery thereof is sealed with a metal material or the like. In other words, these techniques eliminate SAW and the like in FIG.
The device is being downsized.

The former prior art (Japanese Patent Laid-Open No. 4-293)
No. 310), a ground electrode is formed on the surface of a piezoelectric crystal substrate so as to surround the interdigital electrodes, a ground electrode is also formed on the surface of the package substrate, and a solder material is interposed between the ground electrodes. Thus, a constant space is formed between the interdigital electrodes of the SAW element and the package substrate, and the side circumference of this space is sealed. Further, in the latter conventional technique, the side circumference and the back surface of the SAW element are covered with a resin adhesive or the like and further covered with a metal material such as Al from the outside. It should be noted that it is possible to cover the space above the interdigital electrode of the SAW element from the external space with only resin to cover the resin adhesive from the outside with a metal material, but the resin alone is not sufficient in terms of airtightness. Because there is no.

[0006]

However, the techniques described in JP-A-4-293310 and JP-A-2-186662 are all excellent in terms of downsizing the SAW device. However, there is a problem that the manufacturing cost is increased due to a complicated manufacturing process.

That is, the former prior art (Japanese Patent Laid-Open No. 4-2
No. 93310), the ground electrode of the SAW element and the ground electrode of the package substrate are electrically connected to each other, and a metal frame is formed so as to have a constant gap between the two electrodes by a solder material. In order to connect, all electrodes must have a metal surface with good solder wettability and free from solder erosion. Therefore, it is necessary to subject the surfaces of both ground electrodes to metallization. In particular, since the ground electrode of the SAW element has an interdigital electrode in the vicinity thereof, it is necessary to accurately perform a troublesome metallizing process using a mask or the like so that the interdigital electrode is not subjected to the metallizing process. Specifically, for example, when the ground electrode body is made of pure Al or an Al-based alloy, the ground electrode body is covered with a barrier metal such as Ti or Cr in order to prevent solder erosion, and solder is further formed on the ground electrode body. In order to secure the wettability, it is necessary to perform a metallizing process such as laminating a metal such as Cu or Ni. Further, a solder dam or the like must be formed so that the solder material does not flow to the interdigital electrodes, etc., which increases the number of manufacturing steps and increases the manufacturing cost. In the latter prior art (Japanese Patent Laid-Open No. 2-186662), vapor deposition by sputtering in a vacuum container may be considered as a method of further covering the outside of the resinous adhesive with a metal material. The facility cost increases and it takes time to form the metal film.

The present invention has been made by paying attention to such a conventional problem, and provides a SAW device capable of downsizing the device and reducing the manufacturing cost, and a manufacturing method thereof. With the goal.

[0009]

A SAW device for achieving the above object comprises a piezoelectric substrate, an interdigital electrode formed on the surface of the piezoelectric substrate, and an electrode for supplying electric power to the interdigital electrode. Surface acoustic wave device having a pad (hereinafter, SA
W element) and the SAW element mounted,
SA including an electrode pad for supplying electric power to the electrode pad of the device.
In the W device, the surface of the SAW element (the surface on which the interdigital electrode and the electrode pad are formed) and the surface of the package substrate (the electrode pad for supplying electric power to the electrode pad of the SAW element) (The surface on the side on which is formed), so that a space with a constant interval is formed between the interdigital electrode formed on the surface of the SAW element and the surface of the package substrate. A conductive material is interposed between the electrode pads to electrically connect the electrode pads to each other, so that the space is shielded from an external space, at least between the SAW element and the package substrate. Is covered with a resin material containing metal particles having good solder wettability and free from solder erosion (hereinafter referred to as metal particle-containing resin material), and the outer surface of the metal particle-containing resin material is semi-finished. And it is characterized in that it is covered with wood.

Here, in the SAW device, insulation is provided between the SAW element and the package substrate so as to surround the space, at the outer periphery of the space and on the space side of the metal particle-containing resin material. A resin may be provided. Further, in the SAW device, between the electrode pad of the SAW element and the electrode pad of the package substrate, a resin adhesive or resin adhesive containing a rigid space securing conductive material and an anisotropic conductive material. A sheet (hereinafter referred to as an anisotropic conductive material-containing resin material) is interposed to electrically connect the two electrode pads to each other, and the anisotropic conductive material-containing resin material further surrounds the space. You may enclose it.
Further, in the above SAW device, when the size of the SAW device is large to some extent, it is preferable that the substrate body of the package substrate is made of lithium aluminosilicate ceramics.

[0011]

In the present invention, in order to completely hermetically seal the space above the interdigital electrode from the external space, the side periphery of this space is not directly covered with the solder material, but after being covered with the metal particle-containing resin material, The outer surface is covered with a solder material. Therefore, for electrical connection between the electrode pad of the SAW element and the electrode pad of the package substrate, it is not necessary to use a solder material, and various connection methods can be selected. That is,
It is possible to adopt a connection method that does not require the metallizing process on the electrode pad of the SAW element. However,
In order to secure a space above the interdigital electrodes, it is necessary to interpose a conductive material having rigidity between the electrode pad of the SAW element and the electrode pad of the package substrate.

Therefore, a rigid conductive material is interposed between the electrode pad of the SAW element and the electrode pad of the package substrate without performing the metallizing process on the electrode pad of the SAW element to electrically connect both electrode pads. As a connection method to be performed, specifically, for example, a wire bump method often used for face-down connection of a semiconductor integrated circuit is used.
A method is conceivable in which a bump (a conductive material having rigidity) is formed on the electrode pad of the AW element, and the bump and the electrode pad of the package substrate are connected by a thermocompression bonding method or a thermosonic method. In addition, after forming a bump on the electrode pad of the SAW element, an anisotropic conductive material-containing resin adhesive or an anisotropic conductive material-containing resin adhesive is formed between the bump and the electrode pad of the package substrate. A method of arranging a sheet and connecting the bump and the electrode pad of the package substrate with this adhesive or the adhesive sheet is also conceivable.

Further, in the present invention, since the resin material containing the metal particles having good solder wettability and free from solder erosion is used as the resin material for covering the space above the interdigital electrode, When the is covered with a metal material, a solder material that can be easily applied in a normal environment can be used. Therefore, when covering the outside of the resin material with metal, it is not necessary to use a special device.

As described above, according to the present invention, the troublesome metallizing process and the solder dam forming process can be eliminated, and the need for using a special device is eliminated.
The manufacturing cost can be reduced.

[0015]

EXAMPLES Various examples of the SAW device according to the present invention will be described below with reference to FIGS. First, a first embodiment of the SAW device according to the present invention will be described with reference to FIGS.
Will be explained.

As shown in FIG. 1, the SAW device of the present embodiment is configured to have a SAW element 10 and a package substrate 20 on which the SAW element 10 is mounted.

As shown in FIGS. 1 and 4, the SAW element 10 includes a piezoelectric substrate 11 and one surface of the substrate 11 (hereinafter, this surface is referred to as a front surface 12 and the other surface is referred to as a back surface 13).
The interdigitated electrodes 14, 14, ... Formed on the electrodes, the electrodes for supplying electric power to the interdigitated electrodes 14, 14 ,.
That is, the signal electrodes 15, 15 and the ground electrodes 16, 16, ...
And is configured. Note that the SAW in FIG.
The cross section of the element 10 is a cross section taken along the line I-I in FIG. 4.
The interdigital electrodes 14, 14, ... Are formed near the center of the surface 12 of the piezoelectric substrate 11, and the signal electrodes 15, 15 and the ground electrodes 16, 16 ,. Are scattered around. These crossing finger electrodes 14, signal electrodes 15, and ground electrodes 16 are all pure A
1 or Al alloy. On the signal electrode 15 and the ground electrode 16, respectively, by the wire bump method used for face-down connection of the semiconductor integrated circuit,
A signal electrode bump 17 and a ground electrode bump 18 made of Au or Al wire are formed. In addition, these bumps 1
7 and 18 are made of Au or Al, and the electrodes 15 and 16 are made of pure Al or Al-based alloy.
5 and 16 without any metallization
Bumps 17, 18 on electrodes 15, 16 by the wire bump method
Can be formed. That is, when the bumps 17 and 18 are formed on the electrodes 15 and 16 by the wire bump method,
Considering the material forming the bumps 17 and 18, in comparison with the material forming the electrodes 15 and 16, it is not necessary to perform metallization on the electrodes 15 and 16 without introducing a new technique. Absent.

On the other hand, the package substrate 20 is shown in FIGS.
As shown in FIG. 2, the substrate body 21, and the signal electrodes 25 a and 25 b and the ground electrode 2 formed on the substrate body 21.
6a and 26b. On one surface of the package substrate body 21 (hereinafter, this surface is referred to as the front surface 22 and the other surface is referred to as the back surface 23), as shown in FIG.
The element-side signal electrode 25a is the signal electrode 15 of the SAW element 10.
And the element side ground electrode 26a is formed at a position corresponding to
It is formed around the package substrate body 20 so as to surround a position corresponding to the ground electrode 16 of the AW element 10 and the element-side signal electrode 25a. On the back surface 23 of the package substrate body 20, as shown in FIG.
6b is formed on the entire back surface 23 of the substrate body 21 so as to form an H shape, and the external signal electrodes 25b and 25b are
It is formed at a position corresponding to the concave portion of the character. In addition,
The cross section of the package substrate 20 in FIG. 1 is a cross section taken along the line I-I in FIG. 2. In addition, in FIG. 2, the position of the cross indicates the bump connection position. A device-side signal electrode 25 formed on the surface 22 of the package substrate body 21.
a and the element-side ground electrode 26a are the external-side signal electrode 25b and the external-side ground electrode 2 which are formed on the back surface 23 of the substrate body 21 through the through holes 27 and 28, respectively.
6b is connected. The package substrate body 21 is made of lithium aluminosilicate ceramics,
Signal electrodes 25a, 25b and ground electrodes 26a, 26b
Is formed of sintered W or sintered Cu. The element-side signal electrode 25a and the element-side ground electrode 2 of the package substrate 20
6a is Ni-plated and Au-plated thereon in order to enhance the bondability with the corresponding bumps 17 and 18.

As shown in FIG. 1, the package substrate 20 and the SAW element 10 have their surfaces 22 and 12 facing each other, and the package substrate surface 22 and the SAW element 1 are arranged.
It is connected so as to form a constant gap with the interdigitated electrode 14 formed on the surface 12 of 0. This connection is made by connecting the signal electrode bumps 17 and the ground electrode bumps 18 of the SAW device 10 to the device-side signal electrodes 2 of the package substrate 20.
5a and the element-side ground electrode 26a are connected by a thermocompression bonding method or a thermosonic compression bonding method, respectively. In this case, each of the bumps 17 and 18 has a SAW element 10.
Electrodes 15 and 16 of the package substrate 20 and the electrodes 25a of the package substrate 20,
26a and electrically connects the package substrate surface 22 and the cross finger electrode 14 formed on the surface 12 of the SAW element 10 at a constant distance.

SA mounted on the package substrate 20
As shown in FIG. 1, the W element 10 has a back surface 13, a side peripheral surface 19, and a peripheral side portion 12 a of the front surface 12 covered with a metal particle-containing adhesive 30. SAW element 10
With the metal particle-containing adhesive 30 that covers the side peripheral surface 19 of the and the peripheral side portion 12a of the surface 12, the package substrate surface 2
The space S formed between 2 and the interdigital electrode 14 formed on the surface of the SAW element 10 is shielded from the outside. That is, the space S in FIG.
This is covered with the AW element 10, the lower part is covered with the package substrate 20, and the side periphery of the space S is covered with the metal particle-containing adhesive 30 (shown in FIG. 5). As the metal particles of the metal particle-containing adhesive 30, a Cu-based metal having good solder wettability and free from solder erosion is used. The adhesive itself of the metal particle-containing adhesive 30 is a thermosetting epoxy adhesive.

However, normally, the resin cannot completely block moisture and gas. Therefore, in the present embodiment, the solder material 3 is further attached to the outside of the cured adhesive 30 containing metal particles.
5, the space S on the interdigital electrode 14 formed on the surface 12 of the SAW element 10 is hermetically sealed from the external space. The cured adhesive 30 contains metal particles having good solder wettability and no solder erosion, and has good bondability with the solder material 35. The adhesive 30 can be covered with a metal (in this case, the solder material 35) by simply attaching it to the outside.

By the way, the metal particle-containing adhesive 30 covering the side periphery of the space S adheres to the element-side ground electrode 26a formed on the periphery of the surface 22 of the package substrate body 21, as shown in FIG. However, it is supplied so as not to reach the peripheral portion 26a ′ of the element-side ground electrode 26a. On the peripheral portion 26a 'of the ground electrode 26a,
It is covered with the solder material 35. That is, the solder material 35 covers the outer surface of the metal particle-containing adhesive 30 and the peripheral portion 26a ′ of the ground electrode 26a. in this way,
Since the outside of the boundary portion between the package substrate 20 and the metal particle-containing adhesive 30 is covered with a metal (in this case, the solder material 35 and the element-side ground electrode 26a of the package substrate 20),
The space S on the interdigital electrode 14 can be more completely hermetically sealed from the external space. The element-side ground electrode 26
As mentioned above, a is Ni plating, and
Since u plating is applied, not only the bondability with the bumps 17 and 18 but also the solder wettability is good.

Next, a method of manufacturing the SAW device of this embodiment will be described with reference to FIG. FIG. 1A shows a multi-cavity package substrate 100. The multi-cavity package substrate 100 already has the electrodes 25 described above.
a, 26a, 25b, 26b and through holes 27, 28
Are formed at predetermined positions. In addition, each electrode 25a,
The surfaces of 26a, 25b and 26b are plated with Ni and Au. In addition, a plurality of package substrates 20,
The multi-cavity package substrate 100 having 20, ...
Along the boundary line between the package substrates 20 and 20,
The groove 101 is formed.

FIG. 2B shows a state in which the SAW devices 10, 10, ... Are respectively connected to the package substrates 20, 20 ,. The bumps 17 and 18 are formed on the electrodes 15 and 16 of the SAW element 10 by the wire bump method as described above, before being connected to the package substrate 20. When connecting the package substrate 20 and the SAW element 10, first,
A plurality of SAs are arranged on a predetermined position of the multi-cavity package substrate 100 so that their front surfaces 12 and 22 face each other.
The W elements 10, 10, ... Are placed. Then, each SAW element 1
.. are heated while applying ultrasonic waves to the SAW elements 10, 10 ,. Then, since the device-side electrodes 25a and 26a of the package substrate 20 are plated with Ni and Au, the device-side electrodes 25a and 26a and the bumps 17 and 1 are formed.
8 and 8 are connected together.

FIG. 1C shows a plurality of SAW elements 10, 1.
It shows a state in which the metal particle-containing adhesive printing mask 102 is placed on the multi-cavity package substrate 100 to which 0, ... Are connected. In this print mask 102, a plurality of openings 103 that are slightly larger than the size of the SAW element 10 are formed. When placing a large number of this print mask 102 on the package substrate 100, the print mask 10
, The SAW element 10,
Make 10, ... come.

FIG. 3D shows a state in which the adhesive 30 containing metal particles is printed and supplied. When the SAW element 10 is covered with the metal particle-containing adhesive 30, the metal particle-containing adhesive 30 is supplied to the openings 103, 103, ... Of the print mask 102. Then, the metal particle-containing adhesive 30 is supplied to the target position, and the SAW element 10 is supplied with the metal particle-containing adhesive 30.
And the space S on the interdigital electrode 14 is shielded from the external space.

After the metal particle-containing adhesive 30 is printed and supplied, the print mask is removed as shown in FIG.
The metal particle-containing adhesive 30 is cured by heating. In this example, the heating temperature and the heating time required for this heat curing are 150 ° C. and 20 to 30 minutes, respectively. It goes without saying that the heating temperature and the heating time are determined according to the type of the adhesive itself of the metal particle-containing adhesive 30 and are not determined unconditionally.

When the adhesive 30 containing metal particles is hardened, solder flux is applied to the outer surface thereof. And SA
The portion of the W element 10 is immersed in the solder bath from the back surface 13 side thereof, and the outer surface of the cured metal particle-containing adhesive 30 is covered with the solder material 35 as shown in FIG.
The space S above 4 is completely hermetically sealed from the external space. With the above, a plurality of SAW devices are basically completed. In this way, each SA is connected with a plurality of SAW devices.
Perform the characteristic inspection of the W device.

Finally, as shown in FIG. 9G, the multi-cavity package substrate 100 is folded along the groove 101 of the multi-cavity package substrate 100 to separate each SAW device. In addition, a multi-piece package substrate 100
The groove 101 provided in the above is for facilitating separation at the end of the process, and is not particularly necessary when cutting with a dicer or the like.

As described above, in this embodiment, the space S on the interdigital electrode 14 is completely airtightly sealed from the external space.
The side periphery of the space S is not directly covered with the solder material, but is covered with the metal particle-containing adhesive 30 and then the outer surface thereof is covered with the solder material 35. Therefore, the electrode 1 of the SAW element 10
Regarding the electrical connection between 6 and the electrode 26a of the package substrate 20, there is no need to use a solder material, and various connection methods can be selected. That is, it is possible to employ a connection method that does not require the metallizing process on the electrodes 15 and 16 of the SAW element 10. As a result, it is possible to eliminate the step of performing a very troublesome metallizing process and the solder dam forming step on the electrodes 15 and 16 of the SAW element 10.

Further, in this embodiment, as the adhesive covering the side periphery of the space S on the interdigital electrode 14, an adhesive 30 containing metal particles having good solder wettability and free from solder erosion.
When the outer side is covered with a metal material, the solder material 35 can be easily applied in a normal environment.
Can be used. For this reason, it is not necessary to use a special device when the outside of the adhesive is covered with metal. Further, when the outer surface of the adhesive 30 is covered with the solder material 35, the SAW element 10 only needs to be immersed in the solder bath, so that the work itself becomes very easy.

As described above, in this embodiment, it is possible to eliminate the troublesome process and eliminate the need to use a special device, so that the manufacturing cost can be reduced.

Further, in this embodiment, the material of the package substrate body 21 is selected in consideration of the difference in the coefficient of thermal expansion between the piezoelectric substrate 11 used for the SAW element 10 and the package substrate body 21, so that the SAW element is selected. Manufacturing process or SAW after connection between the package 10 and the package substrate 20
The difference in thermal expansion between the two due to temperature changes during use of the device can be minimized. As a result, it is possible to prevent fatigue failure in the connection portion between the both. Here, the thermal expansion coefficients of the piezoelectric substrate 11 and the package substrate body 21 will be briefly described. The coefficient of thermal expansion of the piezoelectric crystal (usually a crystal such as LiTaO ₃ or LiNbO ₃ ) forming the piezoelectric substrate 11 is 15 × depending on the crystal plane orientation.
Some exceed 10 to ⁶ / ° C. On the other hand, in this embodiment, the coefficient of thermal expansion of the lithium aluminosilicate ceramics forming the package substrate body 21 is 8
In ~18 × 10 ~ ⁶ / ℃, a and widespread relatively thermal expansion coefficient is large as ceramics. Therefore, by selecting a lithium aluminosilicate-based ceramic material having a coefficient of thermal expansion close to that of the piezoelectric substrate 11, the difference in coefficient of thermal expansion between the piezoelectric substrate 11 and the package substrate body 21 can be minimized. .

Next, a second embodiment of the SAW device according to the present invention will be described with reference to FIG. SA of this embodiment
The W device is one in which the insulating resin 31 is provided on the side circumference of the space S on the interdigital electrode 14 and inside the metal particle-containing adhesive 30 (on the side of the space S). This is similar to the first embodiment. An epoxy resin is used here as the insulating resin 31.

The insulating resin 31 is supplied to the corresponding position with a syringe after the SAW element 10 and the package substrate 20 are connected. Then, after the insulating resin 31 is heated and cured, the metal particle-containing adhesive 30 is printed and supplied.

In this embodiment, the same effect as that of the first embodiment can be obtained, and in the process of printing and supplying the metal particle-containing adhesive 30, the cross finger electrodes 14 are contaminated by the metal particle-containing adhesive 30. Can be prevented by the insulating resin 31.

Next, a third embodiment of the SAW device according to the present invention will be described with reference to FIG. In this embodiment, S
An anisotropic conductive material-containing adhesive 32 is used when connecting the bumps 17 and 18 connected to the AW device 10 and the device-side electrodes 25a and 26a of the package substrate 20. The anisotropic conductive material-containing adhesive 32 is one in which the conductive material in the adhesive is subjected to a specific treatment so that when the load is applied to the adhesive, the conductive material gathers at the place where the load is concentrated. Is. Therefore, the anisotropic conductive material-containing adhesive 32 is supplied to the bumps 17 and 18 connected to the SAW element 10, and the SAW element 10 to which the bumps 17 and 18 are connected is pressed against the package substrate 20. Then, as shown in FIG. 8, the conductive material in the anisotropic conductive material-containing adhesive 32 causes the bumps 17 and 18 and the element-side electrode 25 of the package substrate 20.
a, 26a and the two are electrically connected to each other.

Therefore, the bumps 17, 1 of the SAW element 10 are
8 and the device-side electrodes 25a and 26a of the package substrate 20 are electrically connected to each other.
It is not necessary to plate a. Also, this anisotropic conductive material-containing adhesive 32 is, like the insulating resin 31 of the second embodiment described above, on the side periphery of the space S on the interdigital electrode 14 and also on the metal particle-containing adhesive. Since it is located inside 30, contamination of the interdigital electrode 14 can be prevented. That is, by using the anisotropic conductive material-containing adhesive 32, the bumps 17 and 18 of the SAW device 10 and the device side electrodes 25a and 26a of the package substrate 20 are electrically connected and the cross finger electrode 14 is electrically connected. Contamination control can be treated in the same step. The same effect can be obtained by using a commercially available anisotropic conductive sheet instead of the anisotropic conductive material-containing adhesive 32.

As described above, the metal particle-containing adhesive 30 and the solder material 35 in various examples of the SAW device according to the present invention are
Both of them are also provided on the back surface 13 side of the SAW element 10, but this is for supplying the solder material 35 by the dipping method in the printing supply process of the solder material 35, and for the purpose of hermetic sealing. It is not configured as such. Therefore, in the step of supplying the solder material 35, when the solder material 35 is not supplied by the dip method, the adhesive 30 containing the metal particles is used.
It is not necessary to supply the solder material 35 to the back surface 13 side of the SAW element 10.

In the above embodiment, the package substrate 20 is made of lithium aluminosilicate ceramics. However, when the SAW device has a size of several mm or less,
Since it is no longer necessary to consider the difference in thermal expansion between the SAW element 10 and the package substrate 20, in such a case, the alumina-based ceramics (coefficient of thermal expansion: 6 × 10 6) usually used as a material for forming the package substrate 20. The package substrate 20 may be formed at about ⁶ / ° C.).

[0041]

According to the present invention, it is not necessary to subject the electrode pad of the SAW element to metallization or to form a solder dam, and it is not necessary to use a special device such as a sputtering device. The cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a SAW device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the surface of the package substrate of the first embodiment according to the present invention.

FIG. 3 is a diagram showing a back surface of the package substrate according to the first embodiment of the present invention.

FIG. 4 is a view showing the surface of the SAW device of the first embodiment according to the present invention.

5 is a sectional view taken along line VV in FIG.

FIG. 6 is an explanatory view showing the manufacturing process of the SAW device of the first embodiment according to the present invention.

FIG. 7 is a cross-sectional view of essential parts of a SAW device according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view of essential parts of a SAW device according to a third embodiment of the present invention.

FIG. 9 is a cross-sectional view of a conventional SAW device.

[Explanation of symbols]

10 ... SAW device, 11 ... Piezoelectric substrate, 12 ... (Piezoelectric substrate) front surface, 13 ... (Piezoelectric substrate) back surface, 14 ... Interdigital electrode, 15 ... Signal electrode, 16 ... Ground electrode, 17 ... Signal electrode bump, 18 ... Ground electrode bump, 20 ... Package substrate, 21 ... Substrate body, 22 ... (Package substrate) front surface, 23 ... (Package substrate) back surface, 25a ... Element side signal electrode, 25b ... External signal electrode, 26a ... Element side ground electrode, 26b ... External side ground electrode, 27, 28 ... Through hole, 30 ... Metal particle-containing adhesive, 31 ... Insulating resin,
32 ... Anisotropic conductive material-containing adhesive, 35 ... Solder material, 100
... multi-cavity package substrate, 101 ... groove (of multi-cavity package substrate), 102 ... printing mask, 103 ...
Opening (of the printing mask).

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Seiichi Ogawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Incorporated company Hitachi Ltd. AV equipment division

Claims (5)

[Claims] 1. A surface acoustic wave device (hereinafter referred to as a SAW device) having a piezoelectric substrate, an interdigital electrode formed on the surface of the piezoelectric substrate, and an electrode pad for supplying electric power to the interdigital electrode. A surface acoustic wave device having the SAW element mounted thereon and a package substrate having an electrode pad for supplying electric power to the electrode pad of the SAW element formed thereon. The surface on which the finger electrodes and the electrode pads are formed) faces the surface of the package substrate (the surface on which the electrode pads for supplying electric power to the electrode pads of the SAW element are formed). However, a conductive material is provided between the electrode pads of the SAW element so that a space with a constant interval is formed between the interdigital electrodes formed on the surface of the SAW element and the surface of the package substrate. In order to electrically connect the two electrode pads to each other through the interposition and to shield the space from the external space, at least the space around the SAW element and the package substrate has good solder wettability. And a resin material containing metal particles without solder erosion (hereinafter referred to as a metal particle-containing resin material), and an outer surface of the metal particle-containing resin material is covered with a solder material. Surface acoustic wave device. 2. An insulating resin is disposed between the SAW element and the package substrate so as to surround the space, at the outer periphery of the space and on the space side of the metal particle-containing resin material. The surface acoustic wave device according to claim 1, wherein 3. The electrode pads of the SAW element are scattered on the surface of the piezoelectric substrate and around the interdigital electrodes, and the electrode pads of the package substrate are the electrode pads of the SAW element. A resin containing a space-providing conductive material and an anisotropic conductive material which are formed between the electrode pad of the SAW element and the electrode pad of the package substrate and which have rigidity between them. An adhesive or a resin adhesive sheet (hereinafter referred to as an anisotropic conductive material-containing resin material) is interposed to electrically connect the two electrode pads to each other. The electrode pad of the SAW element and the electrode pad of the package substrate are electrically connected, and the electrode pad is provided on the outer periphery of the space and on the space side of the metal particle-containing resin material and surrounds the space. hand The surface acoustic wave device as claimed in claim 1, wherein Rukoto. 4. The surface acoustic wave device according to claim 1, wherein the substrate body of the package substrate is formed of lithium aluminosilicate ceramics. 5. A surface acoustic wave element (hereinafter referred to as a SAW element) having a piezoelectric substrate, an interdigital electrode formed on the surface of the piezoelectric substrate, and an electrode pad for supplying electric power to the interdigital electrode. And a package substrate on which the SAW element is mounted and an electrode pad for supplying electric power to the electrode pad of the SAW element is formed, wherein a plurality of the package substrates are provided. It is possible to form a multi-cavity package substrate integrally formed on a plane and to form a plurality of the SAW elements so as to cover the entire front surface of the multi-cavity package substrate. The surface on the side where the interdigital electrodes and the electrode pads are formed is the front surface, and the surface opposite to this surface corresponds to the shape of the back surface)
A mask in which a plurality of openings slightly larger than the size of the back surface of the W element is formed at a position corresponding to the SAW element mounting position of the multi-cavity package substrate is prepared in advance, and And the crossing formed on the surface of the SAW element by facing the surface of the package substrate (the surface on the side where the electrode pad for supplying electric power to the electrode pad of the SAW element is formed). A conductive material is interposed between the two electrode pads to electrically connect the two electrode pads to each other so that a space with a constant interval is formed between the finger electrodes and the surface of the package substrate. The mask is arranged on the multi-cavity package substrate so that the plurality of SAW elements mounted on the multi-cavity package substrate fit within the plurality of openings of the mask. A thermosetting resin material (hereinafter referred to as a metal particle-containing resin material) containing metal particles having good solder wettability and free from solder erosion is supplied onto the back surfaces of the plurality of SAW elements from above. The back surface of the SAW element and the SAW
The periphery of the space between the element and the package substrate is covered with the metal particle-containing resin material to shield the space for each of the plurality of SAW elements from the external space, and the mask is formed from the multi-cavity package substrate. After the removal, the metal particle-containing resin material is heated to cure the metal particle-containing resin material, the plurality of SAW elements are mounted, and the space for each SAW element is covered with the metal particle-containing resin material. The multi-cavity package board is immersed in a molten solder bath from the side on which the SAW element is mounted, and the outer surface of the metal particle-containing resin material is covered with a solder material. A method for manufacturing a surface acoustic wave device, characterized in that a plurality of the surface acoustic wave devices are manufactured by separating each of the package substrates.