JPH07283556A - Airtight terminal structure of package - Google Patents

Abstract

PURPOSE:To provide an airtight terminal structure of a package with less deterioration in electrical characteristics without deteriorating mechanical strength and airtightness. CONSTITUTION:The title structure consists of a metal package 11 where a through hole 12 is formed, a terminal 13 positioned in the through hole 12, and an insulator 14 filled into a smaller section than the total length of the through hole 12 out of the space formed between the terminal 13 and a wall surface 12a of the through hole 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package airtight terminal structure for hermetically forming terminals provided through a package constituting a high frequency device or the like.

[0002]

2. Description of the Related Art A conventional airtight terminal structure of a package will be described with reference to FIG. Reference numeral 81 is a part of the package, and the package 81 is provided with a through hole 82.
Then, the terminal 83 is arranged in the through hole 82, and the terminal 8
3 and the wall surface 82a of the through hole 82 between the insulator 8 such as glass
4 is filled and made airtight.

By the way, in the case of the airtight terminal structure of the conventional package, the diameter and thickness of the insulator 84 and the diameter of the terminal 83 are determined in consideration of the mechanical strength and airtightness of the terminal 83. The thickness of the insulator 84 in the extension direction of the terminal 83 is substantially equal to the thickness of the package 81. The terminal 83, the package 81, the insulator 84
Constitutes one coaxial line. At this time, the characteristic impedance of the coaxial line constituted by the terminal 83, the package 81, etc. is usually lower than that of the characteristic impedance system used in high-frequency equipment or the like, for example, 50 ohm system or 75 ohm system.

[0004]

By the way, when the characteristic impedance of the coaxial line formed by the terminals, the package, etc. is lower than the desired characteristic impedance system, when such a coaxial line is used in the desired characteristic impedance system,
Impedance matching cannot be achieved and electrical characteristics such as VSWR (voltage standing wave ratio) deteriorate. Further, such deterioration of the electrical characteristics becomes more serious as the frequency becomes higher.

Therefore, it can be considered to increase the characteristic impedance in order to reduce the deterioration of the electrical characteristics.
For example, the diameter of the terminal 83 may be reduced, or the diameter of the insulator 84 may be increased. However, if the diameter of the terminal 83 is made small and the portion of the insulator 84 is made large, the mechanical strength of the terminal is deteriorated and the airtightness is impaired.

The present invention solves the above-mentioned drawbacks, and an object of the present invention is to provide an airtight terminal structure for a package in which deterioration of electrical characteristics is suppressed without deteriorating mechanical strength and airtightness.

[0007]

An airtight terminal structure for a package according to the present invention includes a metal package having a through hole,
It is composed of a terminal located in the through hole and an insulator filled in a section shorter than the entire length of the through hole in a space formed between the terminal and a wall surface of the through hole.

The through holes are formed so that the diameter of the portion filled with the insulator is smaller than the diameter of the portion not filled with the insulator.

[0009]

According to the above construction, the terminal, the insulator, and the package form a coaxial line having the terminal as a central conductor. Further, this coaxial line has a portion with an insulator and a portion without an insulator. The coaxial line in the part without the insulator has a relative dielectric constant of 1 between the center conductor and the package, and its characteristic impedance is higher than the desired characteristic impedance system and inductive. Further, the coaxial line in the portion where the insulator is present has a characteristic impedance lower than that of a desired characteristic impedance system and becomes capacitive due to the presence of the insulator. Therefore, it is possible to match the desired characteristic impedance with the capacitive property of the coaxial line having the insulator and the low characteristic impedance and the inductive property of the coaxial line having the insulator and having the high characteristic impedance. As a result, deterioration of electrical characteristics such as VSWR can be reduced.

Further, by making the diameter of the portion not filled with the insulator larger than the diameter of the portion filled with the insulator, the characteristic impedance of the coaxial line in the portion without the insulator can be further increased.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the sectional view of FIG. Reference numeral 11 is a part of the package, and a through hole 12 is formed in the package 11. Then, the terminal 13 is arranged in the center of the through hole 12. Also terminal 13
And an insulator 14 such as glass between the wall surface 12a of the through hole 12 and
Is filled and made airtight. The insulator 14 is filled only in a section shorter than the entire length of the through hole 12, for example, the central portion. Therefore, there is no insulator 14 at both upper and lower ends of the through hole 12, and only the terminal 13 is formed. With the above configuration, the terminal 13, the insulator 14, and the package 11 form a coaxial line having the terminal 13 as a central conductor.

It should be noted that one end of the terminal 13 is connected to the high-frequency substrate 15
It is connected to the microstrip line 16 formed in. In addition, the diameter and thickness of the insulator 14 or the terminal 13
The diameter of is determined in consideration of the mechanical strength and airtightness of the terminal 13.

FIG. 2 is an equivalent circuit of the airtight terminal structure portion of the package shown in FIG. 21A and 21C are equivalent circuits at both ends of the through hole having no insulator, and 21B is an equivalent circuit of the central portion of the through hole having the insulator. For example, the input side portion, that is, the portion indicated by the equivalent circuit 21A forms a coaxial line having a high characteristic impedance, and the impedance A becomes inductive. Further, the central portion of the through hole having the insulator, that is, the portion indicated by the equivalent circuit 21B constitutes a coaxial line having a low characteristic impedance, and the impedance B becomes capacitive. The output side portion, that is, the portion indicated by the equivalent circuit 21C constitutes a coaxial line having a high characteristic impedance. With such a structure, the airtight terminal structure of the package matching the desired characteristic impedance system C is realized. As a result, deterioration in electrical characteristics such as VSWR at high frequencies can be reduced.

FIG. 3 shows the locus of impedance at points A to C in the equivalent circuit shown in FIG. As can be seen from this figure, the desired characteristic impedance system C can be matched.

Further, as shown in FIG. 1, the terminal 13 constituting the airtight terminal structure of the package is connected to the microstrip line 16.
In the case of the connection with, the space without the insulator 14 is formed in the through hole 12 portion on the microstrip line 16 side. This space acts to relieve the mechanical stress on the terminal 13. Therefore, it is not necessary to provide a space for relieving mechanical stress between the package 11 and the electrode on the microstrip line 16.

4 and 5 show another embodiment of the present invention. In these embodiments, the portion without the insulator 14 is formed only at one end of the through hole 12. For example, in FIG. 4, a portion without the insulator 14 is formed above the through hole 12, that is, on the input side. In FIG. 5, the insulator 1 is provided below the through hole 12, that is, on the output side.
4 forms a part without. In this case also, the insulator 14
By the presence or absence of the above, a coaxial line having a low characteristic impedance and a coaxial line having a high characteristic impedance are formed, and an airtight terminal structure of a package that matches a desired characteristic impedance system is obtained. 4 and 5, the parts corresponding to those in FIG. 1 are designated by the same reference numerals, and overlapping description will be omitted.

FIG. 6 is another embodiment of the present invention. In the case of FIG. 6 as well, parts corresponding to those of FIG. 1 are designated by the same reference numerals, and the description will be centered on the parts different from FIG. In this embodiment, the coaxial line having a high characteristic impedance is formed by removing the insulator below the through hole 12 formed in the package 11, for example, on the output side. On the input side, a connecting piece 61 such as a gold ribbon or a gold wire is mounted on the terminal 13, and the connecting piece 61 is connected to a line (not shown) on the circuit board 62 provided on the package 11 in a direction perpendicular to the terminal 13.
Are connected. In this case, the inductance component of the connection piece 61 functions like a coaxial line having a high characteristic impedance, and reduces deterioration of electrical characteristics. FIG. 7 is also another embodiment of the present invention. In the case of FIG. 7 as well, parts corresponding to those of FIG. 1 are denoted by the same reference numerals, and the description will be centered on the parts different from FIG. In this embodiment, the diameter of the through hole 12 formed in the package 11 is changed. The diameter of the through hole 12 in the central portion filled with the insulator 14 is set to the insulator 14
Is smaller than the diameter of both ends that are not filled. In this case, the characteristic impedance of the coaxial line formed in the portion not filled with the insulator 14 can be further increased.

[0018]

According to the present invention, it is possible to realize a package hermetic terminal structure in which mechanical strength and airtightness are not deteriorated and electrical characteristics are not significantly deteriorated.

[Brief description of drawings]

FIG. 1 is a sectional view illustrating an embodiment of the present invention.

FIG. 2 is an equivalent circuit illustrating an embodiment of the present invention.

FIG. 3 is a Smith chart illustrating an example of the present invention.

FIG. 4 is a sectional view showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing another embodiment of the present invention.

FIG. 6 is a sectional view showing another embodiment of the present invention.

FIG. 7 is a sectional view illustrating another embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 11 ... Package 12 ... Through hole 12a ... Wall surface 13 ... Terminal 14 ... Insulator 15 ... High frequency substrate 16 ... Microstrip line

Claims (2)

[Claims] 1. A metal package having a through hole,
A hermetic terminal of a package including a terminal located in the through hole and an insulator filled in a space shorter than the entire length of the through hole in a space formed between the terminal and a wall surface of the through hole. Construction. 2. The through hole is formed such that a diameter of a portion filled with the insulator is smaller than a diameter of a portion not filled with the insulator.
Airtight terminal structure of the described package.