JPH09153764A - Manufacture of surface acoustic wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the sealing strength and the air-tightness by improving the flatness of a sealing medium molten and fixed to a metallic cap. SOLUTION: A metallic cap 1 to which a sealing medium 2 is molten and fixed is adhered to a single layer or multi-layer of rectangle ceramic base on which a surface acoustic wave element is mounted. In this case, the flatness of the sealing medium 2 molten and fixed to the metallic cap 1 is selected to be less than 34μm. Then the amount of the sealing medium 2 molten and fixed to a corner of the ceramic base is selected less than the amount of the sides. Furthermore, it is also effective that the width of the sealing medium 2 molten and fixed to the corner of the ceramic base is selected less than the width of the sides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mount package for electronic parts, particularly a surface acoustic wave having a base made of ceramics and a cap made of metal, which are sealed and joined via a sealing material. The present invention relates to a method of manufacturing a device.

[0002]

2. Description of the Related Art In recent years, many surface acoustic wave devices have been used as elements such as filters, delay lines, and oscillators of electronic equipment utilizing radio waves. In particular, surface acoustic wave filters, which are compact and lightweight and have high sharp cutoff performance as filters, have come to be widely used as filters for RF stages and IF stages of mobile terminal devices in the mobile communication field. There is a demand for a highly reliable surface acoustic wave device capable of responding to changes in the operating environment as well as improving characteristics such as out-of-band attenuation near the band.

Conventionally, the surface acoustic wave device which affects the reliability of the surface acoustic wave device is required to protect the element from the external influence and at the same time to accurately hold the internal element and operate its function to the outside. It is said that. Such a surface acoustic wave device is formed by holding a ceramic base to which a surface acoustic wave element on which an electrode pattern having an electrically function is formed is adhered and holding a hollow portion on the electrode pattern of the surface acoustic wave element. And a sealing material for joining the ceramic base and the metal cap. A ceramic base is generally made of alumina, glass ceramic, etc., and is used as a single-layer or multi-layer flat plate or box type.By etching the Ag / Pd alloy layer, etc. on this flat plate or box type bottom surface, A surface layer conductor pattern is formed and is electrically connected to the electrode pattern on the surface acoustic wave element by wire bonding or the like.

In the surface acoustic wave device, a surface acoustic wave element is placed on a ceramic base, and then wire bonding or the like for electrically connecting the ceramic base and the surface acoustic wave element is performed, and finally, the cap and the ceramic base. It is manufactured by airtightly sealing and bonding the and to each other through a sealing material such as a brazing material. When performing airtight sealing bonding with a sealing material,
First, the sealing material is temporarily welded and fixed to the cap, which is referred to as fusion. After this, the ceramic base and the sealing material fused cap are sealed and joined. The fusion method is generally performed by placing an encapsulant processed to an appropriate size on the joint surface of the cap, raising it to a temperature exceeding the encapsulant melting temperature by passing through a tunnel furnace, and then cooling. I do. Conventionally, the amount of the sealing material, which is the sealing material, is equal to that of the corner portion and the side portion of the rectangular package, or the sealing material is dimensioned so that there are more corner portions.

[0005]

However, when fusion is performed by the conventional method, the sealing material such as AuSn or PbAgSn is melted and becomes liquid, so that the surface tension is large. Therefore, the sealing material is applied to the corner portion of the rectangular package. Gather and cool as it is.
Therefore, the sealing material after fusion is excessively bulged in the cap corner portion, and the side portion of the cap is insufficient and lower than the corner portion. Are not evenly distributed over the entire sealing joint, and the cross section of the encapsulant becomes convex at each part, making it impossible to secure the flatness of the encapsulant fused to the sealing joint of the cap. There was a problem.

Further, during fusion, the sealing material rises to a temperature exceeding the fusion temperature in a state where it is not pressed down by anything, and is then cooled. There was a problem that could not be.

As a result of the above, in the sealing and joining step, when the fused cap and the ceramic base are overlapped with each other, the sealing material and the base come into contact with each other at the corners, but the side portion where the sealing material is insufficient. However, there is a problem in that a gap is not opened, and even if a tunnel furnace is passed for sealing and joining, the gap is not completely eliminated and airtight sealing failure easily occurs, and reliable sealing and joining cannot be obtained. It was

The present invention has been made to address such a problem, and improves the flatness of the sealing material fused to the sealing joint portion of the cap, and makes the entire sealing joint portion uniform. By distributing, the sealing strength and airtightness are improved,
It is an object of the present invention to provide a method of manufacturing a surface acoustic wave for surface mounting which has a high sealing yield and high reliability.

[0009]

According to a first aspect of the present invention, there is provided a method of manufacturing a surface acoustic wave device, comprising: a fusion fixing step of fusion-fixing a sealing material to a metal cap; and a cap via the fixed sealing material. And a sealing and bonding step of bonding a single-layer or multi-layer ceramic base on which a surface acoustic wave element is mounted, in a method of manufacturing a surface acoustic wave device, wherein a flat sealing material fused and fixed to a metal cap is provided. The feature is that a sealing material having a property of less than 34 μm is used.

According to a second aspect of the present invention, there is provided a method of manufacturing a surface acoustic wave device, wherein a fusion fixing step of fusion-fixing a sealing material to a metal cap, and a cap and a surface acoustic wave element via the fixed sealing material. In a method of manufacturing a surface acoustic wave device, comprising: a sealing and bonding step of bonding a mounted single-layer or multi-layer ceramic base, in the fusion fixing step, the amount of the sealing material is a side portion of the rectangular ceramic base. It is characterized in that the sealing material is fused and fixed in a smaller amount in the corner portion.

According to a third aspect of the present invention, there is provided a method of manufacturing a surface acoustic wave device, wherein a fusion fixing step of fusion-fixing a sealing material to a metal cap, and a cap and a surface acoustic wave element via the fixed sealing material. In a method of manufacturing a surface acoustic wave device, which comprises a sealing and bonding step of bonding a mounted single-layer or multi-layer ceramic base, in the fusion fixing step, the layer thickness or layer width of the sealing material is a rectangular ceramic base. It is characterized in that the sealing material is fused and fixed with a thin layer thickness or a narrow layer width in a corner portion rather than a side portion.

According to a fourth aspect of the method of manufacturing a surface acoustic wave device of the present invention, a fusion fixing step of fusion-fixing a sealing material to a metal cap, and a cap and a surface acoustic wave element are interposed via the fixed sealing material. In a method of manufacturing a surface acoustic wave device, which comprises a sealing bonding step of bonding a placed single-layer or multi-layer ceramic base, the fusion fixing step comprises applying pressure to both sides of the sealing material to perform fusion bonding. It is characterized by doing.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a surface acoustic wave device, wherein a fusion fixing step of fusion-fixing a sealing material to a metal cap, and a cap and a surface acoustic wave element via the fixed sealing material. In a method of manufacturing a surface acoustic wave device, which comprises a sealing and bonding step of bonding a mounted single-layer or multilayer ceramic base, in the fusion fixing step, the sealing material is placed on a flat jig and the cap is attached. It is characterized in that it is covered with it and the sealing material is pressed and fused by the weight of the cap.

In the surface acoustic wave device according to claim 1,
The flatness of the sealing material fused and fixed to the metal cap is 34 μ.
When it is less than m, the sealing strength and the airtightness of the package are improved. As a result, a high sealing yield and a highly reliable surface acoustic wave device can be obtained. In the present invention, the flatness is defined as the amount of warpage that can be represented by the distance between the straight line connecting the raised ends of the sealing material after fusion bonding and the sealing material at the center of the side. An example of the measurement portion of the warp amount is shown in FIGS. 1 to 3.

In the method of manufacturing a surface acoustic wave device according to claims 2 and 3, the amount of the brazing material as a sealing material is set to be smaller in the corner portions than in the side portions of the rectangular ceramic base, or By making the layer thickness or layer width of the encapsulant thinner or narrower in the corner portions than in the side portions of the rectangular ceramic base, the following operational effects are produced.

Since the surface tension is large when the encapsulant is melted and becomes a liquid, the amount of the encapsulant is set with respect to the corners of the rectangular package in consideration of the fact that the encapsulant gathers at the corners of the rectangular package. Less than the sides. Alternatively, the layer thickness or layer width of the sealing material is set to be thinner or narrower in the corner portions than in the side portions. As a result, the encapsulant gathers at the corners, and the encapsulant after fusion adheres to the corners of the cap excessively, and the edges of the cap are insufficient and are lower than the corners. Therefore, the sealing material fused to the sealing joint is evenly distributed over the entire sealing joint, and the flatness of the sealing material fused to the sealing joint of the cap can be ensured. it can.

When the flat sealing material is fused and sealed by the cap, the fused cap and the ceramic base are overlapped with each other at both corners and sides. There was almost no gap between the two, and a good sealing bond was obtained.

The process of sealingly joining the metal cap to the ceramic base on which the surface acoustic wave device is mounted and maintaining the airtightness of the package are important items for improving the productivity. According to the present invention, the flatness of the sealing material fused to the sealing joint portion of the cap is improved, the sealing material is evenly distributed over the entire sealing joint portion, and the sealing strength and airtightness are improved. It is possible to realize a surface acoustic wave device that is improved and has a high sealing yield and is highly reliable for surface mounting applications.

In the method of manufacturing a surface acoustic wave device according to claims 4 and 5, the flatness of the sealing material fused to the sealing and bonding portion of the cap is ensured by the sealing material before sealing and bonding. During the fusion process of temporarily welding and fixing to the cap, pressure is applied to both sides of the encapsulant to fuse them, or the encapsulant is placed on a flat jig and the cap is placed on top of it, This is done by pressing and sealing the sealing material. With such a method, the same effects as those of claims 1 to 3 can be obtained.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 The invention according to claims 1 to 3 will be described with reference to Table 1 and FIGS. 1 to 4. FIG. 1 shows the shape of the sealing material according to Example 1, and FIGS. 2 and 3 show the shape of the sealing material according to the comparative example.
FIG. 4 shows an example of a surface acoustic wave device using those sealing materials. 1 to 3, (a) is a perspective view showing a state in which a sealing material is stacked on a cap before fusion, and (b) is a flatness of the sealing material on the cap from the side after fusion. The figure which looked at is shown. Here, the cap 1 is made of Kovar, and has dimensions of 6.3 mm x 6.3 mm and a thickness of 0.15 mm. Sealant 2 is PbA
As gSn, the width of the sealing joint was 0.7 mm and the thickness was 0.05 mm. This sealing material 2 was fused to the cap 1.

In Example 1 shown in FIG. 1, the amount of the sealing material at the corners was reduced in order to improve the flatness of the sealing material after fusion bonding.
The narrowest part of the corner is about 60% of the side. Comparative Example 1 and Comparative Example 2 shown in FIGS. 2 and 3, respectively, are conventional examples, and in particular, the amount of the sealing material at the corners is not reduced, and the sealing material after fusion is made equivalent to the side portions. The flatness is not improved.

The flatness of each of Example 1, Comparative Example 1 and Comparative Example 2 was measured, and a sealing test was performed using the ceramic base 3 shown in FIG. 4, and a sealing hermeticity test (leak test) was performed. . Table 1 shows the results.

[0023]

[Table 1] As shown in Table 1, since Example 1 is superior in flatness as compared with Comparative Examples 1 and 2, a good result was shown in the leak test.

When the sealing material was AuSn in Example 1, the same results as those shown in Table 1 were obtained.

Embodiment 2 Regarding the inventions according to claims 4 and 5, Table 2 and FIG.
The description will be made with reference to FIGS. 6 and 4. FIG. 5 shows the shape of the sealing material according to Example 2, and FIG. 6 shows the shape of the sealing material according to Comparative Example 3. In addition, in FIGS. 5 and 6, (a)
Is a perspective view showing a state in which a sealing material and a cap are placed in this order on a fusion jig before fusion, (b) is a cross-sectional view taken along the line AA ′ of (a), and (c) is fusion. The figure which shows the flatness of the sealing material on a cap later from a side surface, and (d) shows the figure which looked at the flatness of the sealing material on the cap of the AA 'cross section after fusion bonding, respectively. The same cap 1 and sealing material 2 as in Example 1 were used, and this sealing material 2 was aligned with the cap 1 and fused.

In the second embodiment shown in FIG. 5, in order to improve the flatness of the sealing material after fusion bonding, the fusion jig 4 is used so that the sealing material 2 can be fused with the cap 1 placed thereon. Then, pressure was applied to the sealing material by the weight of the cap. Comparative Example 3 shown in FIG.
This is a conventional example, and the sealing material 2 was placed on the cap 1 and placed in the fusion jig 4 so as not to shift.

For Example 2 and Comparative Example 3, flatness was measured under the same conditions and methods as in Example 1, and a sealing test was performed using the ceramic base 3 shown in FIG. A leak inspection was performed. Table 2 shows the results.

[0028]

[Table 2] As shown in Table 2, since Example 2 is superior to Comparative Example 3 in flatness, it showed a good result in the leak test.

The same results as shown in Table 2 were obtained when AuSn was used as the sealing material in Example 2.

[0030]

According to the method of manufacturing a surface acoustic wave device of claim 1, the flatness of the sealing material fused and fixed to the metal cap is
Since the encapsulant having a size of less than 34 μm is used, the flatness of the encapsulant fused to the encapsulation joint of the cap is improved and the encapsulant is uniformly distributed over the entire encapsulation joint. As a result, sealing strength and airtightness are improved, a high sealing yield is obtained, and a highly reliable surface acoustic wave device for surface mounting is obtained.

In the method of manufacturing the surface acoustic wave device according to any one of claims 2 to 5, since the flatness of the sealing material fused to the sealing joint portion of the cap can be improved, the sealing strength and the airtightness can be improved. Of the surface acoustic wave device with improved reliability, high encapsulation yield, and high reliability for surface mounting.

[Brief description of the drawings]

FIG. 1 is a diagram showing a shape of a sealing material according to a first embodiment.

FIG. 2 is a diagram showing a shape of a sealing material according to Comparative Example 1.

FIG. 3 is a diagram showing a shape of a sealing material according to Comparative Example 2.

FIG. 4 is a diagram showing an example of a surface acoustic wave device.

FIG. 5 is a diagram showing a shape of a sealing material according to a second embodiment.

FIG. 6 is a diagram showing a shape of a sealing material according to Comparative Example 3.

[Explanation of symbols]

1 ... Metal cap, 2 ... Sealing material, 3 ... Ceramic base, 4 ... Fusion jig.

Claims (5)

[Claims] 1. A fusion-fixing step of fusion-bonding a sealing material to a metal cap, and a single-layer or multi-layer ceramic on which the cap and the surface acoustic wave element are mounted via the fixed sealing material. In a method of manufacturing a surface acoustic wave device, which comprises a sealing bonding step of bonding with a base, the flatness of the sealing material fused and fixed to the metal cap is 3
A method of manufacturing a surface acoustic wave device, which comprises using an encapsulant having a size of less than 4 μm. 2. A fusion fixing step of fusion-bonding a sealing material to a metal cap, and a single-layer or multilayer ceramic on which the cap and the surface acoustic wave element are mounted via the fixed sealing material. In the method of manufacturing a surface acoustic wave device, which includes a sealing and bonding step of bonding with a base, in the fusion fixing step, the amount of the sealing material is smaller in a corner portion than in a side portion of the rectangular ceramic base. A method for manufacturing a surface acoustic wave device, characterized in that the sealing material is fused and fixed in an amount. 3. A fusion-bonding fixing step of fusion-bonding a sealing material to a metal cap, and a single-layer or multilayer ceramic on which the cap and the surface acoustic wave element are mounted via the fixed sealing material. In the method of manufacturing a surface acoustic wave device, the method comprising: a sealing bonding step of bonding a base, wherein the fusion fixing step has a layer thickness or a layer width of the encapsulating material that is more square than a side portion of the rectangular ceramic base. The method of manufacturing a surface acoustic wave device, wherein the encapsulant is fused and fixed with a thin layer thickness or a narrow layer width at the portion. 4. A fusion fixing step of fusion-fixing a sealing material to a metal cap, and a single-layer or multi-layer ceramic on which the cap and the surface acoustic wave element are mounted via the fixed sealing material. A method of manufacturing a surface acoustic wave device, comprising: a sealing bonding step of bonding a base; and the fusion fixing step, wherein pressure is applied to both surfaces of the sealing material to perform fusion bonding. Device manufacturing method. 5. A fusion-fixing step of fusion-fixing a sealing material to a metal cap, and a single-layer or multi-layer ceramic on which the cap and the surface acoustic wave element are mounted via the fixed sealing material. In a method of manufacturing a surface acoustic wave device having a sealing and bonding step of bonding a base, in the fusion fixing step, the sealing material is placed on a flat jig,
A method for manufacturing a surface acoustic wave device, comprising: covering a cap with the cap, pressing the sealing material by the weight of the cap, and fusing.