JP3802388B2 - High frequency circuit equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-frequency circuit device used for a wireless communication device or the like.
[0002]
[Prior art]
A conventional high-frequency circuit device will be described with reference to FIG. Reference numeral 31 denotes a metal case, on which a high-frequency package 32 and a circuit board 33 that house high-frequency circuit components such as field effect transistors are arranged. The high frequency package 32 is directly arranged on the metal case 31 by using, for example, a notch provided in the circuit board 33. A radio wave absorber 34 is disposed on the high frequency package 32. The radio wave absorber 34 absorbs a high-frequency signal that returns from, for example, the output side to the input side of the high-frequency package 32, suppresses coupling between input and output, and prevents oscillation. The high frequency package 32 and the radio wave absorber 34 are sealed with a shield cover 35.
[0003]
The high-frequency package 32 and the circuit board 33 are fixed by screws (not shown), and the shield cover 35, the circuit board 33, and the metal case 31 are fastened by screws 36 and fixed together.
[0004]
[Problems to be solved by the invention]
In the conventional high-frequency circuit device, circuit components housed in the high-frequency package 32, such as field effect transistors, generate heat during operation, and the temperature of the high-frequency package 32 rises. The heat of the high-frequency package 32 is radiated through, for example, a metal case 31.
[0005]
When the heat of the high frequency package 32 is radiated to the metal case 31, for example, the high frequency package 32 is directly disposed on the metal case 31 in order to improve heat transfer from the high frequency package 32 to the metal case 31. It is fixed with screws and brought into close contact.
[0006]
However, in the method of fixing the high frequency package 32 and the metal case 31 with screws, the screws are fixed at a plurality of locations in order to bring the contact surfaces of the high frequency package 32 and the metal case 31 into close contact. As a result, the area of the fixed portion or the fixed portion increases, the degree of freedom in circuit pattern design is lost, miniaturization, mass production, and cost reduction become difficult, and electrical characteristics deteriorate.
[0007]
An object of the present invention is to solve the above-described drawbacks and to provide a high-frequency circuit device that can be easily downsized and mass-produced.
[0008]
[Means for Solving the Problems]
The present invention includes a case, a circuit board on which a high frequency package containing circuit components is mounted and disposed on the case, a radio wave absorber disposed on the high frequency package, the high frequency package, and the radio wave absorber. In a high-frequency circuit device comprising a shield cover for sealing, and a screw for fastening and fixing the shield cover, the circuit board, and the case, the shield cover and the radio wave so that a force for fastening the screw is applied to the radio wave absorber. The absorber is mechanically coupled.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG. Reference numeral 11 denotes a metal case, and the metal case 11 is grounded, for example. A circuit board 12 is disposed on a metal case 11, and a high frequency package 13 containing a high frequency circuit element such as a field effect transistor is mounted on the circuit board 12. The high-frequency package 13 is, for example, a surface mount type, and is mounted on the circuit board 12 by a method such as automatic mounting or automatic soldering.
[0010]
On the high-frequency package 13, a radio wave absorber 14 in which ferrite, iron powder or the like is mixed with silicon rubber is disposed. The radio wave absorber 14 absorbs a high frequency signal that returns from the output side to the input side of the high frequency package 13, for example, and suppresses coupling between input and output to prevent oscillation.
[0011]
A space around the high-frequency package 13 and the radio wave absorber 14, for example, a side portion and an upper portion are sealed with a shield cover 15. The shield cover 15 includes a frame body portion 15a that surrounds the side portions of the high-frequency package 13 and the radio wave absorber 14, and a lid portion 15b that closes the opening of the frame body portion 15a. The shield cover 15, the circuit board 12, and the metal case 11 are fastened with screws 16 and fixed integrally. When the shield cover 15 or the like is fixed with the screw 16, the shield cover 15 and the radio wave absorber 14 are in direct contact, for example, and both are mechanically coupled.
[0012]
According to the above-described structure, the shield cover 15 and the radio wave absorber 14, the high frequency package 13, the circuit board 12, and the metal case 11 are sequentially in contact, for example, and the radio wave absorber is interposed between the shield cover 15 and the metal case 11. 14, the high-frequency package 13, and the circuit board 12 are mechanically sandwiched.
[0013]
In this case, when the shield cover 15, the circuit board 12, and the metal case 11 are fixed with the screws 16, the force for tightening the screws 16 is transmitted from the shield cover 15 to the radio wave absorber 14 and from the high-frequency package 13 to the circuit board 12. Then, the circuit board 12 and the metal case 11 are firmly adhered.
[0014]
As a result, good heat transfer characteristics are obtained between the circuit board 12 and the metal case 11, and heat generated in the high-frequency package 13 is efficiently radiated to the case 11 through the circuit board 12. In addition, since the contact surface between the circuit board 12 and the metal case 11 is in close contact, the circuit board 12 is reliably grounded and good electrical characteristics are realized.
[0015]
In addition, according to the above-described structure, there is no need to fix the high frequency package 13 with the screws 16 or to bond the circuit board 12 and the metal case 11, increasing the degree of freedom of circuit pattern design, and miniaturization and mass production. The price can be easily reduced.
[0016]
Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 2, parts corresponding to those in FIG.
[0017]
In this embodiment, an intermediate member such as a conductive member 21 is sandwiched between the shield cover 15 and the radio wave absorber 14. In this case, the conductive member 21 has a structure in which iron powder or the like is mixed into a soft insulating material having a higher elasticity than that of the radio wave absorber 14, for example, or a rubber is mixed with metal powder such as a silver filler. Is used.
[0018]
In the case of the above configuration, when the shield cover 15, the circuit board 12, and the case 11 are fixed with the screws 16, the shield cover 15 and the conductive member 21 come into contact with each other. A force for tightening the screw 16 is transmitted from the shield cover 15 to the radio wave absorber 14 via the conductive member 21 and further transmitted to the high frequency package 13 and the circuit board 12, and the circuit board 12 and the metal case 11 are connected. Adhering to each other, good heat transfer characteristics can be obtained between the circuit board 12 and the metal case 11. Further, the circuit board 12 is reliably grounded, and good electrical characteristics are realized.
[0019]
By the way, in the embodiment of FIG. 1, the shield cover 15 and the radio wave absorber 14 are in direct contact. In this case, since the radio wave absorber sheet 14 is hard, the radio wave absorber 14 may be crushed and deformed by a force received from the shield cover 15 when the screw 16 is tightened. When the radio wave absorber 14 is deformed, the frequency characteristics change, and it may not be possible to sufficiently prevent signal coupling between input and output, and oscillation may occur.
[0020]
In the structure of FIG. 2, a conductive member 21 that is more elastic and softer than the radio wave absorber 14 is sandwiched between the shield cover 15 and the radio wave absorber 14. In this case, since the force of the shield cover 15 is applied to the conductive member 21 and is not directly applied to the radio wave absorber 14, the deformation of the radio wave absorber 14 is suppressed. Therefore, there is no change in frequency characteristics, and coupling between input and output is prevented.
[0021]
In FIG. 2, the conductive member 21 is used as an intermediate member disposed between the shield cover 15 and the radio wave absorber 14. However, an insulating member can be used instead of the conductive member 21. Even when an insulating member is used, a force for tightening the screw 16 is applied between the circuit board 12 and the metal case 11, and the same effect can be obtained. However, the shield effect is greater when the conductive member is used.
[0022]
【The invention's effect】
According to the present invention, it is possible to realize a high-frequency circuit device that can be miniaturized and mass-produced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining an embodiment of the present invention.
FIG. 2 is a cross-sectional view for explaining another embodiment of the present invention.
FIG. 3 is a cross-sectional view for explaining a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Metal case 12 ... Circuit board 13 ... High frequency package 14 ... Radio wave absorber 15 ... Shield cover 16 ... Screw 21 ... Conductive member

Claims (4)

A case, a circuit board mounted on the case with a high-frequency package containing circuit components, a radio wave absorber disposed on the high-frequency package, and a shield cover for sealing the high-frequency package and the radio wave absorber And the shield cover, the circuit board, and a screw for fastening and fixing the case, the shield cover and the radio wave absorber are mechanical so that a force for fastening the screw is applied to the radio wave absorber. A high-frequency circuit device characterized by being coupled to each other. The high-frequency circuit device according to claim 1, wherein an intermediate member softer than the radio wave absorber is sandwiched between a shield cover and the radio wave absorber. The high-frequency circuit device according to claim 2, wherein the intermediate member has conductivity. The high-frequency circuit device according to claim 2, wherein the intermediate member is configured by mixing a metal in an insulating material.

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