KR100388055B1 - A SAW duplexer - Google Patents

Abstract

According to the present invention, a surface acoustic wave duplexer mounted with a first RF surface acoustic wave filter package and a second RF surface acoustic wave filter package serving as a transmitting end and a receiving end on an upper surface of a ceramic substrate is connected to the upper surface and the ceramic substrate to form a metal material. It includes a ground connection that forms a through-hole in the upper side of a metal can protecting the internal circuit and shorts the inside with a conductive adhesive. There is an effect that can easily dissipate heat generated from the controlled, embedded surface acoustic wave filter package.

Description

Surface acoustic wave duplexer {A SAW duplexer}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave duplexer, and more particularly, to a surface acoustic wave duplexer having a ground reinforced by mounting a metal can formed with a through hole to protect a circuit by embedding a surface acoustic wave filter on an upper surface of a ceramic substrate.

In general, surface acoustic waves represent a state of waves transmitted along the surface of the substrate and have a feature of rapidly attenuating in the depth direction. The SAW filter uses this feature as a frequency selective device.

That is, the SAW device temporarily forms a metal electrode on a highly insulative substrate and applies a piezoelectric twist to the substrate surface. This action causes a physical wave. Since the wave speed transmitting the SAW element surface is slower than the electromagnetic wave, it is used as a filter to temporarily delay an electric signal or pass only a specific frequency signal.

The SAW filter is a ceramic container that protects a semiconductor device or a function, and is formed in a package form that protects an internal circuit from a harmful environment and provides a means for dissipating heat generated therein and connecting it to the outside.

FIG. 1 shows a structure of a surface acoustic wave duplexer according to the prior art, and a surface acoustic wave duplexer (SAW duplexer) mounts surface acoustic wave filters 2a and 2b having the above structure to a ceramic substrate 1 and its outer surface. Covered with a metal can (3) and shorted between the ceramic substrate (1) and the filters (2a and 2b) and between the metal can (3) and the ceramic substrate (1) using a conductive adhesive (4). It is configured by.

In addition, a microstrip line 5 is formed on the upper surface of the ceramic substrate 1 between the surface acoustic wave filters 2a and 2b to prevent signal interference between the surface acoustic wave filters 2a and 2b.

The cover of the outer surface is formed of a metal can or molding type to protect the circuit inside the package. At this time, in the case of the molding type, heat dissipation is difficult and the ground is hardly strengthened as compared with the case of a metal can.

However, even in a surface acoustic wave duplexer including a metal can cover, it is difficult to release heat generated from the surface acoustic wave filter due to a space enclosed inside the package, and it is difficult to reinforce the ground because connection with the outside is impossible.

The present invention has been made to solve the above problems of the prior art, the object of which is to strengthen the ground by mounting a surface cantilever filter on the upper surface of the ceramic substrate and mounting a metal can formed with a through hole to protect the circuit To provide a surface acoustic wave duplexer with improved frequency attenuation characteristics.

1 is a cross-sectional view showing the structure of a surface acoustic wave duplexer according to the prior art,

2 is a cross-sectional view showing the structure of a surface acoustic wave duplexer according to the present invention;

3a and 3b is a graph showing the comparison between the characteristics of the prior art and the frequency characteristics of the present invention

<Explanation of symbols on main parts of the drawings>

11: ceramic substrate 12a, 12b: RF surface acoustic wave filter package

13 metal can 14 conductive adhesive

15 microstrip line 16 ground connection

According to a feature of the surface acoustic wave duplexer according to the present invention for solving the above problems, a first RF surface acoustic wave filter package which is mounted on a ceramic substrate, the upper surface of the ceramic substrate and having a first frequency pass band as a transmitting end and a receiving end; A second RF surface acoustic wave filter package having a second frequency pass band, a microstrip line formed between the first and second RF surface acoustic wave filter packages to prevent signal interference between a transmitter and a receiver; A metal can connecting an upper surface of the second RF surface acoustic wave filter package and the ceramic substrate to protect an internal circuit with a metal material, and an image contacting the first and second RF surface acoustic wave filter packages of the metal can. Ground reinforcing ground by forming a through hole in the side and shorting the inside with a conductive adhesive It is composed of a.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 illustrates a structure of a SAW duplexer according to the present invention, and includes a first RF surface acoustic wave filter package 12a having a first frequency passband on a top surface of a ceramic substrate 11, and a second frequency passband. The second RF surface acoustic wave filter package 12b is mounted.

The upper and the outer surfaces of the first and second RF surface acoustic wave filter packages 12a and 12b are connected to each other to form a cover with a metal can 13 having a predetermined thickness to close the inside thereof, and to close the ceramic substrate. A conductive adhesive 14 is used to connect the 11 and the filters 12a and 12b and the metal can 13 and the ceramic substrate 11.

At this time, the metal can 13 forms a through hole having a predetermined size on the upper surface of the metal can 13 in contact with the first and second RF surface acoustic wave filter packages 12a and 12b, and shorts the inside of the through hole using a conductive adhesive. The first and second RF surface acoustic wave filter packages 12a and 12b and the metal can 13 may be contacted by forming the ground connection 16.

The conductive adhesive 14 may be a solder, silver paste, electrical welding, or the like, which is an alloy of tin and lead.

In addition, a microstrip line 15 is formed on an upper surface of the ceramic substrate 11 between the surface acoustic wave filter packages 12a and 12b to prevent signal interference between the surface acoustic wave filter packages 12a and 12b.

The ground is further strengthened by the ground connection 16 to improve the attenuation characteristics at the antenna and at the side lobe of the receiver at the transmitting end of the first and second RF surface acoustic wave filter packages 12a and 12b. It is possible to eliminate the feedthrough that may occur in the micro strip line.

3a and 3b show the characteristics of the surface acoustic wave duplexer according to the prior art and the surface acoustic wave duplexer according to the present invention. FIG. 3a shows the frequency characteristics from the transmitting end to the antenna, and FIG. 3b from the antenna to the receiving end.

In FIG. 3A, the high frequency attenuation characteristic of the duplexer Tx2 in which the ground connection is formed is improved compared to the duplexer Tx1 in which the ground connection is not provided, and in FIG. It can be seen that the low frequency attenuation characteristic of is improved.

As described above, the surface acoustic wave duplexer according to the present invention improves attenuation by ground strengthening and easily dissipates heat generated by the embedded surface acoustic wave filter package.

The surface acoustic wave duplexer of the present invention configured as described above includes a surface acoustic wave filter package on the upper surface of the ceramic substrate and mounts a metal can formed with a through hole to protect the circuit, thereby improving ground, thereby improving frequency attenuation characteristics. The feed-through is controlled and has the effect of easily dissipating heat generated from the embedded surface acoustic wave filter package.

Claims (3)

A first RF surface acoustic wave filter package having a first frequency pass band and a second RF surface acoustic wave filter package having a first frequency pass band as a transmitting end and a receiving end mounted on a ceramic substrate, the upper surface of the ceramic substrate; And a microstrip line formed between the second RF surface acoustic wave filter package to prevent signal interference between the transmitting end and the receiving end, and connecting the upper surfaces of the first and second RF surface acoustic wave filter packages to the ceramic substrate. A metal can protecting an internal circuit and a through hole formed in an upper surface of the metal can in contact with the first and second RF surface acoustic wave filter packages, and the ground is shorted by a conductive adhesive. Surface acoustic wave duplexer, characterized in that consisting of the ground connection to strengthen. The method of claim 1, The conductive adhesive of the ground connection portion is a surface acoustic wave duplexer, characterized in that the use of solder (silver or silver paste), electrical welding and the like. The method of claim 1, The ground connection portion is in contact with a metal can and the first and second RF surface acoustic wave filter packages to improve frequency attenuation characteristics of each filter and to discharge heat generated from an embedded surface acoustic wave filter package. Surface acoustic wave duplexer.