JP3910423B2 - Package structure of SAW device - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a SAW device, and more particularly to a SAW device package structure that provides an effective new shield structure for elements mounted inside the SAW device.
[Prior art]
[0002]
In a conventional SAW device, as a means for reducing high-frequency noise that affects the characteristics of elements mounted inside the SAW device, a conductive material is used for the upper surface, side surface, and lower surface of the SAW device as shown in FIG. It used to be shielded.
[0003]
Therefore, in order to shield the upper surface, side surface, and lower surface of the SAW device with a conductive material, conventionally, the substrate material of the container of the SAW device is ceramic or the like, as shown in FIG. A conductive metal metallization layer is formed on the bottom plate and side surfaces of the inner surface of the container, and a metal lid called a lid is mounted using a conductive sealing material such as brazing material, solder, or conductive adhesive. In general, the container of the SAW device is sealed.
[0004]
In other words, in the conventional method, the upper surface, the side surface, and the lower surface of the element mounted inside the SAW device are shielded by enclosing the three directions with the conductive material, and at the same time, the conductive material is used for joining the container and the lid of the SAW device. Sealing was performed using this sealing material.
[0005]
The configuration of a conventional SAW device is shown in FIG. As shown in FIG. 8, in the conventional SAW device, the upper surface, the side surface, and the lower surface of the SAW device are made conductive as means for reducing high-frequency noise that affects the characteristics of the element 1 mounted inside the SAW device. It was the structure which shields using material. That is, in FIG. 8, in order to shield the upper surface of the element 1 inside the SAW device and the side and lower surfaces of the container with a conductive material, the substrate material of the SAW device container 2 is ceramic. In the same manner, the bottom plate and the side surface of the inner surface are formed on the ceramic substrate by the conductive metal metallization layer 6, and the conductive sealing material 5 such as brazing material, solder, or conductive adhesive is used to form a metal called a lid. It was common to seal the container 2 of the SAW device by mounting a lid 3 made of the product.
[Problems to be solved by the invention]
However, in recent years, with the miniaturization of equipment used for mounting electronic components, there is a very rapid demand from the market for the reduction in the outer shape of the container shape and the reduction in height.
[0006]
In the structure of the conventional SAW device as described above, a shield in which all directions of internal elements are surrounded by a conductive material, such as using a metal lid for the bottom plate, side surface, and lid of the container. It was necessary to have a structure. In addition, in this conventional structure, the sealing surface of the container and the lid are made of a conductive material for shielding the upper surface, so there are restrictions on the sealing material that can be used, and sealing is also costly. It is necessary to use a high sealing material, and as a result, there is a limit in reducing the cost as a whole.
[0007]
The present invention solves the above problems, and can use a material such as plastic whose container portion is less expensive than a conventional ceramic, and does not require a lid made of a conductive material such as metal. The present invention provides a package structure for a SAW device that is inexpensive compared to the prior art and uses an inexpensive non-conductive lid and the sealing material is not limited to a conductive material.
[0008]
[Embodiments of the Invention]
Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, the same code | symbol in each figure shall show the same object.
[0009]
FIG. 1 is a high-frequency noise resistance diagram when the upper and lower surfaces of the elements inside the SAW device are shielded. A level indicated by a circled arrow in FIGS. 1 to 3 is called a noise floor level. In FIG. 1, the noise floor level is about 75 dB. FIG. 2 is a high-frequency noise characteristic diagram when only the lower surface of the element inside the SAW device is shielded. The noise floor level rises compared to FIG. 1 due to the high frequency noise, and deteriorates to about 60 dB. FIG. 3 is a graph showing high-frequency noise resistance when the lower and side surfaces of the elements inside the SAW device are similarly shielded. From the above results, it can be seen that a noise floor level of about 75 dB equivalent to that in FIG. 1 is obtained by shielding only the lower and side surfaces of the element. Compared to FIGS. 1 and 2, FIG. 3 shows that the number of samples for which high-frequency noise resistance is measured is not a reciprocal, but actually the high-frequency noise resistance equivalent to FIG. It is also obtained in a plurality of sample measurements under the condition that only the lower and side surfaces are shielded.
[0010]
From the above results, the shielding effect is high when the side surfaces of the elements inside the SAW device are shielded. Accordingly, by shielding only the lower surface and side surfaces, high-frequency noise resistance equivalent to that of the conventional SAW device can be obtained. I found out.
[0011]
4 to 7 are diagrams showing an embodiment of the present invention. Both are examples in which the side surface and the lower surface of the element 1 inside the SAW device are shielded by a conductive metal.
[0012]
FIG. 4 shows a structure in which a conductive metal layer 6 is formed on the side surface and the bottom surface of the inner surface of the SAW device container 2 on which the element 1 is mounted. In FIG. 4, the element 1 and the external terminal of the SAW device (not shown in the figure), which are configured on the outer surface of the container 2, are electrically connected via the wire 4. In the embodiment of the present invention from FIG. 4 to FIG. 7, the sealing material 7 for sealing the container 2 does not need to be a conductive material as in the prior art, and therefore the lid 8 is the container 2. And a joint that does not require electrical conductivity.
[0013]
In other words, according to the present invention that does not require the upper surface of the element 1 to be shielded, the sealing material 7 is not restricted to be a conductive material, and the lid 8 is an expensive metal as in the prior art. It is not necessary to be a lid made of metal, and can be made of a material such as plastic or ceramic.
[0014]
FIG. 5 shows another embodiment of the present invention. The conductive metal layer 6 is insert-molded on the lower surface of the inner surface of the container 2 and the inner surface of the inner surface of the container 2. 6 and 7 also show another embodiment of the present invention. FIG. 6 shows an example in which the conductive metal layer 6 is formed on the lower surface and the side surface of the inner surface of the container 2, and FIG. In this example, the conductive metal layer 6 or the conductive metal plate 6 is formed on the lower surface and side surfaces of the element 1. In FIG. 6 and FIG. 7, the element is electrically connected to the external input / output terminal RF _IN or RF _OUT terminal of the SAW device, though not shown in the figure, via bumps 9 drawn in circles in the figure. It is made up. In the embodiment of the present invention, the conductive metal layer 6 or the conductive metal plate 6 that shields the lower surface and the side surface of the element 1 is formed by forming a multilayer metal metallized layer on the ceramic or depositing a metal film on the plastic by vapor deposition. The conductive metal plate 6 is formed or embedded in a plastic container. The conductive metal layer and the conductive metal plate may be used in combination in one package.
[0015]
【The invention's effect】
According to the present invention, the material of the container is made of a material such as plastic or ceramic, and a conductive metal plate is insert-molded therein, or the material of the container of the SAW device, which is inexpensive in cost, in which a conductive metal layer is formed can be used. In addition, there is no need for a costly lid made of a conductive material such as a metal lid for shielding the upper surface, and by using a non-conductive lid, the sealing material is also costly conductive. As a result, it was possible to realize a SAW device package structure that is inexpensive in terms of cost, using a lid made of a material such as plastic or ceramic.
[Brief description of the drawings]
FIG. 1 is a diagram showing high-frequency noise resistance characteristics of a conventional SAW device.
FIG. 2 is a diagram showing high-frequency noise resistance characteristics when only the lower surface of the element inside the SAW device is shielded.
FIG. 3 is a diagram showing high-frequency noise resistance when the lower surface and side surfaces of elements inside the SAW device are shielded.
FIG. 4 is a package cross-sectional view seen from the side, with the lower and side surfaces of the elements inside the SAW device according to the present invention shielded.
FIG. 5 is a package cross-sectional view as seen from the side, with the lower and side surfaces of the elements inside the SAW device according to another embodiment of the present invention shielded.
FIG. 6 is a package cross-sectional view as seen from the side, with the lower and side surfaces of the elements inside the SAW device according to another embodiment of the present invention shielded.
FIG. 7 is a cross-sectional view of a package as seen from the side, with the lower and side surfaces of elements inside the SAW device according to another embodiment of the present invention shielded.
FIG. 8 is a sectional view of a conventional SAW device package as viewed from the side.
DESCRIPTION OF SYMBOLS 1 Element 2 SAW device container 3 Metal lid 4 Wire 5 Conductive sealing material 6 Conductive metal layer or conductive metal plate 7 Nonconductive sealant 8 Nonconductive lid 9 Bump

Claims (1)

      In the SAW device, the SAW device container is made of plastic, and includes a conductive plate that is embedded in the SAW device container and shields a side surface and a lower surface of an element mounted in the SAW device. Package structure of SAW device.

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