JP2001094389A - Surface acoustic wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface acoustic wave(SAW) device improving adhesive in spite of being resin. SOLUTION: In a resin cap 33, an SAW element 21 is positioned in its hollow and a bonding wire 25 is positioned. In a state where a lead frame 23 and a lead frame 24 are made to correspond with the electrode insertion part 36 of a resin base 32 and the electrode insertion recess part 41 of the cap 33 and the projecting part 35 of the base 32 is fitted into the recess part 40 of the cap 33, the base 32 and the cap 33 are connected with adhesives 42 and 43. The base 32 and the frames 23 and 24 are adhered with the adhesive 42 and the cap 33 and the frames 23 and 24 are adhered with the adhesive 43. An SAW device is formed by sealing the element 21 by adhering with the adhesives 42 and 43.

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 which a surface acoustic wave element is housed in a resin case.

[0002]

2. Description of the Related Art Generally, a surface acoustic wave device is a comb-shaped electrode (Inter Digital Transd
ucer) to convert an electric signal into a surface acoustic wave (SAW), and the surface acoustic wave propagating on the piezoelectric substrate is similarly received by a comb-shaped electrode provided on the piezoelectric substrate. It utilizes frequency characteristics related to conversion between an electric signal and a surface acoustic wave, and is widely used, including a surface acoustic wave filter, a surface acoustic wave resonator, or a delay circuit.

[0003] For this reason, in recent years, especially in the field of television and the like, since it can be made thinner and smaller, a surface acoustic wave filter is widely used, and a case for accommodating a surface acoustic wave element is a conventional case. The transition from metal packages to resin packages is in progress.

Conventionally, this type of surface acoustic wave device is formed, for example, according to the manufacturing steps shown in FIGS.

First, as shown in FIG. 7, a surface acoustic wave element 1 having a comb-shaped electrode formed on a piezoelectric substrate is disposed on a lead frame 3 with an adhesive 2.

Next, as shown in FIG. 8, a bonding pad between the surface acoustic wave element 1 and the lead frame 3 is connected by wire bonding 4.

Further, as shown in FIG. 9, a resin cap 5 in the form of a flat plate and a resin cap 6 in the form of a hollow thin box having an open lower surface.
, The lead frame 3 is positioned between the resin base 5 and the resin cap 6, an adhesive 7 is applied around the resin base 5, and an adhesive 8 is applied to a portion where the resin cap 6 is joined.

Then, as shown in FIG. 10, the surface acoustic wave element 1 is positioned hollow in the resin cap 6, the wire bonding 4 is positioned, and the resin base 5 is connected to the surface acoustic wave element 1 of the lead frame 3. The resin cap 6 is adhered to the surface on which the surface acoustic wave element 1 of the lead frame 3 is mounted with an adhesive 8 while the resin cap 6 is adhered to the surface where the surface acoustic wave element 1 is not mounted. A package 9 is formed, the surface acoustic wave element 1 is sealed, and a surface acoustic wave device is formed.

[0009]

However, in the structure shown in FIGS. 7 to 10, since the bonding surface of the resin base 5 and the bonding surface of the resin cap 6 are both flat, the bonding area is small. Depending on the material of the resin base 5 and the resin cap 6, an adhesive strength cannot be obtained.

Therefore, the molding time is short, burrs are not generated at the time of molding, the material can be recycled, and although heat resistance is high, polyphenylene sulfide (PPS) and liquid crystal polymer cannot be used because of poor adhesion. .

Further, the adhesives 7 and 8 must also play a role of sealing, but in a high-temperature and high-humidity atmosphere such as a reliability test, the resin base 5 and the lead frame 3 and the resin cap 6 and the lead frame 3 However, there is a problem that moisture easily enters the resin package 9 from the joint portion of the surface acoustic wave element and the electrode pattern of the comb-like electrode of the surface acoustic wave element 1 may be corroded.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a surface acoustic wave device having improved adhesion even with resin.

[0013]

SUMMARY OF THE INVENTION The present invention relates to a surface acoustic wave device having a piezoelectric substrate, a comb-like electrode provided on the piezoelectric substrate, and a lead frame on which the surface acoustic wave device is mounted. , A resin base and a resin cap attached to the resin base, and a portion where the resin base and the resin cap are joined to each other. And a resin package for accommodating the lead frame, and by forming irregularities opposed to each other at a portion where the resin base and the resin cap are joined, it is possible to increase the bonding area when bonding. As a result, the sealing performance is improved, and the positioning is facilitated.

An electrode which is electrically connected to the surface acoustic wave element and is led out from between the resin base and the resin cap, and a part where the electrode is led out of a portion where the resin base and the resin cap are joined to each other. An electrode insertion portion having no projection is provided, so that the electrode can be easily led out of the resin package.

Further, the resin base and the resin cap are made of a resin containing polyphenylene sulfide, and the molding time is short, burrs are not generated at the time of molding, and the material can be recycled.

Further, the resin base and the resin cap are made of a resin containing a liquid crystal polymer. The molding time is short, no burrs are generated at the time of molding, the material can be recycled, and the heat resistance can be increased.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a surface acoustic wave device according to the present invention will be described below with reference to the drawings.

As shown in FIG.
A surface acoustic wave element 21 having a comb-shaped electrode, which is a tal transducer, is mounted on a lead frame 23 having a projection 23a also serving as an electrode with an adhesive 22. The lead frame 23 is used as a ground, and furthermore, a lead frame serving as an input / output electrode also serving as a suspension bar for maintaining strength.
24 is provided, between the surface acoustic wave element 21 and the bonding pads of the lead frame 23 and the lead frame 24,
They are electrically connected by bonding wires 25.

Reference numeral 31 denotes a resin package containing polyphenylene sulfide or a liquid crystal polymer. The resin package 31 has a resin base 32 and a resin cap 33 covering the resin base 32.

The resin base 32 projects upward from the periphery of the rectangular plate-shaped substrate 34 inward by the thickness of the resin cap 33 toward the rectangular flat plate-shaped substrate 34, and extends substantially along the outer edge of the substrate 34. A portion 35 is formed.
The projection 23a and the lead frame 24 have an electrode insertion portion 36 which is led out.

On the other hand, the resin cap 33 has a flat lid 37 having the same shape as the rectangle of the substrate 34 of the resin base 32. A peripheral wall 38 is formed around the lid 37, and the lower surface is opened. are doing. In addition, a protruding portion of the resin base 32 is provided on the distal end side of the peripheral wall portion 38.
An inner wall portion 39 is formed in parallel with the peripheral wall portion 38 with a gap slightly wider than the width of 35, and the resin base 32 projects between the peripheral wall portion 38 and the inner wall portion 39, that is, inside the thickness direction of the peripheral wall portion 38. Part 35
A concave portion 40 into which is fitted is formed. Further, the height corresponding to the portion of the resin base 32 where the electrode insertion portion 36 is formed on the peripheral wall portion 38 of the resin cap 33,
An electrode insertion recess 41 corresponding to the thickness of 24 is formed.

The protrusions 35 of the resin base 32 correspond to the electrode insertion portions 36 of the resin base 32 and the electrode insertion recesses 41 of the resin cap 33 so that the lead frames 23 and 24 correspond to the recesses 40 of the resin cap 33. In the mated state,
The resin base 32 and the lead frame 23 and the resin base 32 and the resin cap 33 are bonded with an adhesive 42, and the resin cap 33 and the lead frame 23 and the resin base 32 and the resin cap 33 are bonded with an adhesive 43. I have.

Next, a method of manufacturing the surface acoustic wave device according to this embodiment will be described with reference to the manufacturing steps shown in FIGS.

First, as shown in FIG. 2, a surface acoustic wave element 21 having a comb-shaped electrode formed on a piezoelectric substrate is disposed on a lead frame 23 with an adhesive 22.

Next, as shown in FIG.
21 and the bonding pads of the lead frames 23 and 24 are connected by bonding wires 25.

Further, as shown in FIG. 4, the resin base 32 and the resin cap 33 are arranged with the lead frame 23 and the lead frame 24 corresponding to the electrode insertion portion 36 of the resin base 32 and the electrode insertion recess 41 of the resin cap 33. The adhesive 42 is applied around the protrusion 35 of the resin base 32 and the adhesive 43 is applied to the concave portion 40 of the resin cap 33.

Then, as shown in FIG.
While the surface acoustic wave element 21 is located in the hollow in 32,
With the bonding wire 25 positioned, the protrusion 23a of the lead frame 23 and the lead frame 24 correspond to the electrode insertion portion 36 of the resin base 32 and the electrode insertion recess 41 of the resin cap 33, and the protrusion 35 of the resin base 32 is Cap 33 recess
In a state fitted to 40, the resin base 32 and the resin cap 33 are bonded with adhesives 42 and 43, and the resin base 32 and the lead frame 23 or the lead frame 24 are bonded with the adhesive 42, and the resin cap 33 and The lead frame 23 or the lead frame 24 is bonded with an adhesive 43, and the surface acoustic wave element 21 is sealed to form a surface acoustic wave device.

The resin base 32 has a projection 35 formed along the thickness direction of the resin cap 33, and the resin cap 33 has an inner wall 39 formed along the peripheral wall 38. Between 39, i.e., recesses in the thickness direction of the peripheral wall 38
Since 40 is formed, the bonding area increases and the bonding strength increases. Therefore, the resin cap 33 is made of a resin such as polyphenylene sulfide or liquid crystal polymer, which is hardly adhered.
In addition, the resin base 32 can be formed, the molding time is short, burrs are not generated at the time of molding, the material can be recycled, the workability can be improved, and the cost can be reduced.

Further, by fitting the projection 35 of the resin base 32 and the concave portion 40 of the resin cap 33, the alignment between the resin base 32 and the resin cap 33 becomes easy, and the displacement can be prevented.

Further, the resin base 32 and the resin cap
Due to the complicated interface shape of the adhesives 42 and 43 between the resin base 32 and the resin base 32 and the resin cap even in a high temperature and high humidity atmosphere
Moisture hardly permeates into the resin package 31 from the portion where the surface acoustic wave element 33 is joined, and the corrosion of the electrode pattern such as the comb-like electrode of the surface acoustic wave element 21 can be prevented.

In the above embodiment, the resin base 32
Although the protrusion 35 is formed on the resin cap 33 and the recess 40 is formed on the resin cap 33, the recess may be formed on the resin base 32 and the protrusion may be formed on the resin cap 33, or a combination of the two. Similar effects can be obtained.

[0032]

According to the present invention, by forming irregularities opposed to each other at a portion where the resin base and the resin cap are joined, the bonding area can be increased at the time of bonding, thereby improving the adhesiveness. In addition, the sealing property is improved, and the positioning can be easily performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a surface acoustic wave device according to the present invention.

FIG. 2 is a sectional view showing one manufacturing process of the surface acoustic wave device according to the first embodiment;

FIG. 3 is a cross-sectional view showing a next manufacturing step of FIG. 2;

FIG. 4 is a cross-sectional view showing a next manufacturing step of FIG. 3;

FIG. 5 is an exploded perspective view showing the SAW device.

FIG. 6 is a perspective view showing the surface acoustic wave device according to the first embodiment;

FIG. 7 is a cross-sectional view illustrating one manufacturing process of a conventional surface acoustic wave device.

FIG. 8 is a cross-sectional view showing the next manufacturing step of FIG. 7;

FIG. 9 is a cross-sectional view showing the next manufacturing step of FIG. 8;

FIG. 10 is a cross-sectional view showing the next manufacturing step of FIG. 9;

[Explanation of symbols]

 21 Surface acoustic wave element 23 Lead frame 24 Lead frame 31 Resin package 32 Resin base 33 Resin cap 35 Projection 36 Electrode insertion part 40 Concave part

Claims (4)

[Claims] 1. A piezoelectric substrate, a surface acoustic wave element having a comb-like electrode provided on the piezoelectric substrate, a lead frame on which the surface acoustic wave element is mounted, a resin base, and a resin base. A resin package having a resin cap to be attached, a concave portion and a projection corresponding to each other at a portion where the resin base and the resin cap are joined, and accommodating the surface acoustic wave element and the lead frame in the resin base and the resin cap And a surface acoustic wave device comprising: 2. An electrode which is electrically connected to the surface acoustic wave element and is led out from between the resin base and the resin cap, and an electrode is led out of a protrusion at a portion where the resin base and the resin cap are joined. 2. The surface acoustic wave device according to claim 1, further comprising an electrode insertion portion having no projection formed at the portion. 3. The surface acoustic wave device according to claim 1, wherein the resin base and the resin cap are made of a resin containing polyphenylene sulfide. 4. The surface acoustic wave device according to claim 1, wherein the resin base and the resin cap are made of a resin containing a liquid crystal polymer.