JPH09162690A - Device having surface acoustic wave element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the surface acoustic wave element to be miniaturized with high reliability. SOLUTION: A piezoelectric substrate 5 is placed on a mount board 3 via bumps 7a, 7b, an element side sealing 10, and a mount board side seal ring 11 so as to form a space 19 between a side 5a on which a surface acoustic wave from a surface acoustic wave element is propagated and a placing side 3a. Input output electrodes 6a, 6b of the piezoelectric substrate 5 and an extract electrode 14 are connected by the bumps 7a, 7b. Furthermore, the space 19 is air-tight-sealed by the element side sealing 10 and the mount board side seal ring 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device having a surface acoustic wave element, and more particularly to sealing a surface acoustic wave element.

[0002]

2. Description of the Related Art Today, SAW (surface acoustic wave) devices using surface acoustic waves are known. Transversal S belonging to this SAW device
The AW filter will be described with reference to FIG.

An input side electrode 6a and an output side electrode 6b are formed on the surface of the piezoelectric substrate 2. When an electric signal is applied to the input side electrode 6a, the surface of the piezoelectric substrate 2 is distorted and the surface acoustic wave 3 is generated. The surface acoustic wave 3 is output to the electrode 6b.
Is transmitted to That is, the electric signal given to the input side electrode 6a can be taken out by the output side electrode 6b.

[0004] Waves transmitted through the piezoelectric substrate 2 (surface acoustic waves)
Of the input side electrode 6a and the output side electrode 6b
Determined by the intersection length and pitch of the. The input side electrode 6a and the output side electrode 6b are formed into a comb shape, and by changing the cross length and pitch of each of the interdigital transducers (IDTs), a complicated shape such as a band pass filter is obtained. A filter with frequency characteristics can be created. The surface acoustic wave element is suitable for miniaturization, weight reduction, and thinning, and further multifunctionalization and high performance are expected as a key device for mobile personal digital assistants.

As shown in FIG. 5, the surface acoustic wave element (chip) 53 has a multilayer ceramic structure package 55.
It is stored in (55a to 55d). The package 55 and the surface acoustic wave element 53 are connected by an aluminum or gold wire 58. The opening of the package 55 is sealed with an alloy lid 57 such as Kovar by an electric welding method. In this way, a transversal SAW filter including the surface acoustic wave element 53 is completed.

In the surface acoustic wave element 53, since the electric signal is transmitted by the surface acoustic wave, it is necessary to provide such a strict sealing structure on the surface of the piezoelectric substrate so that a passivation film like a normal semiconductor element is formed. Because it is not possible to form.

However, such a structure increases the size as a whole and complicates the structure of the package. Also, parasitic inductance / capacitance of the wire occurs. Furthermore, wire bonding has poor workability and poor mass productivity. Also, with the miniaturization of elements, the package 55 can be miniaturized (about 2.5 mm × 2.5 mm or less). However, if the package is downsized, wire bonding becomes impossible.

An object of the present invention is to solve the above problems and to provide an apparatus having a surface acoustic wave element which is highly reliable and can be miniaturized.

[0009]

According to another aspect of the present invention, there is provided a mounting table having a mounting surface, wherein one end is located on the mounting surface and the other end is on the mounting surface. A mounting table having a take-out electrode located on a surface different from that, above the mounting table, a surface acoustic wave element positioned so as to form a space between the surface on which the surface acoustic waves are transmitted and the mounting surface,
A connection member for electrically connecting the input / output electrode of the surface acoustic wave element and the one end of the extraction electrode, formed on the outer periphery of the input / output electrode between the mounting table and the surface acoustic wave element, and the space And a sealing member for keeping airtight.

In an apparatus having a surface acoustic wave element according to a second aspect, the surface acoustic wave element is held by either or both of the connecting member and the sealing member so as to form the space. It is characterized by being

In a device having a surface acoustic wave element according to a third aspect of the present invention, the surface of the surface acoustic wave element other than the surface through which the surface acoustic wave propagates and the outer peripheral surface of the sealing member are covered with resin. To do.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a device having a surface acoustic wave element, wherein bumps are formed on the surface of the input / output electrodes of the surface acoustic wave element and the first sealing member surrounds the input / output electrodes. And a mounting surface on which a second sealing member having the same outer peripheral shape as the first sealing member is formed, and one end of which is located on the mounting surface and the other end is on a surface different from the mounting surface. A mounting table having an extraction electrode positioned is prepared, and the bump contacts the extraction electrode and the first electrode
The surface acoustic wave element is placed on the mounting table so that the sealing member contacts the second sealing member, and the surface acoustic wave element and the mounting table are integrated. Characterize.

[0013]

In the device having the surface acoustic wave element according to the first aspect, the sealing member is formed on the outer periphery of the input / output electrode between the mounting table and the surface acoustic wave element, and the space is formed. Keep airtight. As a result, it is possible to provide a device having a highly reliable surface acoustic wave element that does not require a strict package as in the past, can be downsized, and is highly reliable.

Further, the surface acoustic wave element is located above the mounting table so as to form a space between the surface on which the surface acoustic waves are transmitted and the mounting surface. The connection member electrically connects the input / output electrode of the surface acoustic wave element and the one end of the extraction electrode. As a result, wire bonding is unnecessary, workability is good, and a device having a surface acoustic wave element with high mass productivity can be provided.

In a device having a surface acoustic wave element according to a second aspect of the present invention, the surface acoustic wave element is held by either or both of the connecting member and the sealing member so as to form the space. There is. Therefore, the connection member,
The space can be formed in either or both of the sealing members.

In a device having a surface acoustic wave element according to a third aspect of the present invention, the surface of the surface acoustic wave element other than the surface through which the surface acoustic wave propagates and the outer peripheral surface of the sealing member are covered with resin. As a result, it is possible to provide a device having a surface acoustic wave element that is more airtight and is resistant to shock.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a device having a surface acoustic wave element, wherein a first sealing member is formed so as to surround an input / output electrode of the surface acoustic wave element, and the first sealing member is a front member. The surface acoustic wave element is mounted on the mounting table so as to come into contact with the second sealing member of the mounting table, and the surface acoustic wave element and the mounting table are integrated. Therefore, it is possible to provide an apparatus having a highly reliable surface acoustic wave element that does not require a strict package as in the conventional case, can be downsized.

Further, the input / output electrodes of the surface acoustic wave element and the extraction electrodes are in contact with each other via the bumps. Thereby, a space is formed between the surface on which the surface acoustic wave is transmitted and the mounting surface. Therefore, the surface acoustic wave element can be protected while functioning. That is, it is possible to provide a device having a surface acoustic wave element that does not require wire bonding, has good workability, and is highly productive.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus having a surface acoustic wave element according to the present invention will be described with reference to the drawings.

FIG. 1 shows a sectional view of a main part of a SAW device 1 which is an apparatus having a surface acoustic wave element according to the present invention.

The SAW device 1 includes a mount substrate 5 which is a mounting table, bumps 7a and 7b which are connection members, a piezoelectric substrate 5, an element side seal ring 10, a mount substrate side seal ring 11 and a resin 29.

Above the mount substrate 3 having the extraction electrode 14 and the mounting surface 3a, a space 19 is formed between the surface 5a on which the surface acoustic wave of the surface acoustic wave element is transmitted and the mounting surface 3a. The piezoelectric substrate 5 is mounted via the bumps 7a and 7b, the element side seal ring 10, and the mount substrate side seal ring 11.

The bumps 7a and 7b connect the input / output electrodes 6a and 6b of the piezoelectric substrate 5 to the lead-out electrode 14. The space 19 is hermetically sealed by the element-side seal ring 10 and the mount substrate-side seal ring 11.

The surface 5c of the piezoelectric substrate 5 facing the surface 5a, the side faces of the element side seal ring 10 and the mount substrate side seal ring 11 are covered with resin 29.

As described above, by using the element-side seal ring 10 and the mount-substrate-side seal ring 11, a space 19 can be formed between the piezoelectric substrate 5 and the mount substrate 3 and hermetically sealed. As a result, there is no need to protect with a ceramic package as in the conventional case, so that the device having the surface acoustic wave element can be downsized as a whole. In the present embodiment,
The element side seal ring 10 and the mount substrate side seal ring 11 constitute a sealing member.

Further, by using the bumps 7a and 7b, it is possible to electrically connect the input / output electrodes 6a and 6b and the take-out electrode 14 while forming a space between the piezoelectric substrate 5 and the mount substrate 3. Becomes This eliminates the need for a bonding wire, thus eliminating the parasitic inductance / capacitance of the wire. Furthermore, the manufacturing process is simplified.

Next, a method of manufacturing the SAW device 1 shown in FIG. 1 will be described. First, as shown in FIG. 2A,
The lift-off method is used to form the aluminum input electrode 6a, the output electrode 6b, and the element-side lower seal ring layer 8 on the surface of the piezoelectric substrate 5. As a result, a surface acoustic wave element having the element-side lower seal ring layer 8 on the outer circumference of the input / output electrode is formed.

Next, using the lift-off method, as shown in FIG. 2B, the bumps 7a and 7b are provided on the filter pad portions 16a and 16b of the input electrode 6a and the output electrode 6b, and the element-side lower seal ring layer 8 is formed. An element-side upper seal ring layer 9 is formed thereon. In this embodiment, the element-side lower seal ring layer 8 and the element-side upper seal ring layer 9 constitute the element-side seal ring layer 10.

In the present embodiment, the element-side upper seal ring layer 9 has a two-layer structure of a nickel barrier metal layer and an Au layer thereon.

Next, a mount substrate 3 as shown in FIG. 3A is prepared. On the mounting surface 3a of the mount substrate 3, there is provided an extraction electrode 14 whose one end is located on this mounting surface and whose other end is located on a surface different from the mounting surface (the back surface in the present embodiment). (See FIG. 1). Further, on the mounting surface 3a, so as to surround the extraction electrode 14,
A mount substrate side seal ring 11 is formed. The outer peripheral shape of the mount substrate side seal ring 11 is shown in FIG.
It has the same shape as the element-side seal ring 10 shown in B. Further, the extraction electrode 14 is provided so as to match the filter pad portions 16a and 16b, as described later.

In this embodiment, the mount substrate side seal ring 11 is formed by printing the seal on gold.
Was formed.

Next, the piezoelectric substrate 5 shown in FIG. 2B is mounted on the mount substrate shown in FIG. 3A so that the mount substrate side seal ring 11 and the device side seal ring 10 overlap each other with the device side seal ring layer 10 facing downward. Place on top of 3. As a result, as shown in FIG. 3B, the bumps 7a and 7b come into contact with the extraction electrode 14, and the mount substrate side seal ring 11 and the element side seal ring 10 come into contact with each other. In this state, temporary pressure bonding is performed, and then reflow is performed to make the piezoelectric substrate 5
And the mount substrate 3 are integrated.

As a result, in the portion of the piezoelectric substrate 5 where the surface acoustic wave is transmitted, the space 19 is formed between the piezoelectric substrate 5 and the mount substrate 3, and the input / output electrodes 6a and 6b and the take-out electrode 14 are electrically connected. Connected to. Further, the space 19 becomes airtight by integrating the piezoelectric substrate 5 and the mount substrate 3 with the mount substrate side seal ring 11 and the element side seal ring 10 in contact with each other.

Then, as shown in FIG. 3B, liquid resin is applied from above the surface 5c of the piezoelectric substrate 5 which faces the surface 5a. This liquid sealing resin cures over time. This makes it possible to prevent damage and the like. In this embodiment, the CRP series (manufactured by Sumitomo Bakelite Co., Ltd.) is adopted as the liquid resin. As a composition,
It is a conventional mold resin with a volatile solvent added.

In this way, the device 1 having the surface acoustic wave element shown in FIG. 1 is formed.

In this embodiment, the mount substrate side seal ring layer 11 is formed on the mount substrate side with the same thickness as the lead electrode 14. Further, the element-side lower seal ring layer 8 is formed with the same thickness as the input electrode 6a and the output electrode 6b. Therefore, bump 7
The element-side upper seal ring layer 9 can be formed with the same thickness as a and 7b.

Further, in the present embodiment, the input electrode 6
a, the output electrode 6b, and the element-side lower seal ring layer 8 are formed of aluminum, the bumps 7a, 7b and the element-side upper seal ring layer 9 have a two-layer structure of nickel and gold in order to improve the bonding degree. . However, the barrier metal is not limited to this, and when the input electrode 6a, the output electrode 6b, and the element-side lower seal ring layer 8 are formed by using another metal, for example, gold, such a barrier metal is unnecessary.

Although the lift-off method is used in this embodiment, the input electrode 6a and the output electrode 6 can be formed by another method.
b, the element-side lower seal ring layer 8, the bumps 7a and 7b, and the element-side upper seal ring layer 9 may be formed.

In this embodiment, the mount substrate 3 is a single layer ceramic. Thereby, a highly reliable SAW device can be provided. However, the material of the mount substrate 3 is not limited to this. For example,
By configuring the mount substrate 3 with a polyimide film, a SAW device with excellent workability can be provided.

Although the transversal SAW filter has been described in the present embodiment, the present invention can be applied to other surface acoustic wave devices such as a resonator SAW filter.

In the present embodiment, the bump 7
a, 7b, the element side seal ring 10 and the mount substrate side seal ring 11, the piezoelectric substrate 5 is mounted on the mount substrate 3
It is held so that a space 19 can be formed between and. However, the present invention is not limited to this, and the piezoelectric substrate 5 may be held by either one.

Further, in this embodiment, the bump 7
Although a, 7b, the element side seal ring 10 and the mount substrate side seal ring 11 are made of the same material (conductor) in the same step, they may be made of different materials in different steps. . For example, the bumps 7a and 7b may be formed by sticker printing. The element-side seal ring 10 and the mount substrate-side seal ring 11 may be made of an insulator.

[Brief description of the drawings]

FIG. 1 shows a SAW device 1 according to an embodiment of the present invention.
It is principal part sectional drawing of.

FIG. 2 is a diagram showing a manufacturing process of the SAW device 1.

FIG. 3 is a diagram showing a manufacturing process of the SAW device 1.

FIG. 4 is a diagram showing a conventional surface acoustic wave device.

FIG. 5 is a diagram for explaining a conventional method for packaging a surface acoustic wave device.

[Explanation of symbols]

 3 ... Mount substrate 5 ... Piezoelectric substrate 6a ... Input side electrode 6b ... Output side electrode 7a ... Bump 7b ... Bump 8: Element lower seal ring layer 9: Element upper seal ring layer 10 Element seal ring layer 11 Mount substrate side seal ring layer 19・ ・ ・ Space 29 ・ ・ ・ Resin

Claims (4)

[Claims] 1. A mounting table having a mounting surface, wherein the mounting table has an extraction electrode having one end located on the mounting surface and the other end located on a surface different from the mounting surface. An upper surface acoustic wave element positioned so as to form a space between the surface through which the surface acoustic wave propagates and the mounting surface, an input / output electrode of the surface acoustic wave element, and the one end of the extraction electrode electrically. A surface acoustic wave, comprising: a connecting member connected to the surface of the input / output electrode between the mounting table and the surface acoustic wave element; and a sealing member that keeps the space airtight. A device having an element. 2. A device having a surface acoustic wave element according to claim 1, wherein the surface acoustic wave element is held by either or both of the connection member and the sealing member so as to form the space. A device having a surface acoustic wave element characterized by being. 3. A device having a surface acoustic wave element according to claim 2, wherein a surface other than the surface of the surface acoustic wave element through which the surface acoustic wave propagates,
And an outer peripheral surface of the sealing member covered with a resin, wherein the surface acoustic wave element is provided. 4. A bump is formed on a surface of an input / output electrode of a surface acoustic wave device, and first bumps are formed so as to surround the input / output electrode.
A mounting surface on which a sealing member is formed and a second sealing member having the same outer peripheral shape as the first sealing member is formed, and one end is located on the mounting surface and the other end is the mounting surface. Preparing a mounting table having extraction electrodes located on different surfaces, such that the bumps contact the extraction electrodes and the first sealing member contacts the second sealing member,
The method for manufacturing an apparatus having a surface acoustic wave element, comprising: mounting the surface acoustic wave element on the mounting table, and integrating the surface acoustic wave element and the mounting table.