Wave transmission lines and networks – Coupling networks – With impedance matching
Reexamination Certificate
1999-06-21
2002-10-15
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Coupling networks
With impedance matching
C333S026000
Reexamination Certificate
active
06466101
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microstrip line-waveguide conversion structure, to an integrated circuit package for high frequency signals employing this conversion structure, and to a manufacturing method therefor, and in particular, relates to a microstrip line-waveguide conversion structure, an integrated circuit package for high frequency signals provided with this conversion structure and a manufacturing method therefor, which are adopted for the airtight sealing of integrated circuits employed in the millimeter band.
2. Background Art
In general, in semiconductor integrated circuit modules employing the millimeter or micrometer wavebands, it is necessary to provide a structure having an airtight seal in order to increase reliability. However, in the millimeter waveband, the physical dimensions of the interface in coaxial bonds employing the glass sealing which was employed in the micrometer waveband become small, and the requirements for manufacturing precision become severe, so that this has not been conducted.
Techniques in which semiconductor integrated circuits are sealed in an airtight manner using waveguides have been proposed. For example, in “60 GHz Band Signal Receiving Module”, which is found on page 136 of the first volume of the Collected Papers of the Electronics Society Conference of the Electronic Information Communication Study Group of 1995, a structure is disclosed which directly converts high frequency signals from a microstrip line to a waveguide and outputs these to the exterior.
FIG. 15A
is a plan cross-sectional view showing the structure of the high frequency interface portion of a conventional integrated circuit package (hereinbelow referred to as Conventional Example 1), while
FIG. 15B
is a cross-sectional view taken along the line I—I in FIG.
15
A.
As shown in
FIGS. 15A and B
, the integrated circuit package of Conventional Example 1 is provided with a package base portion
40
which is made from metal or the like, a waveguide
41
which extends approximately vertically within the package base portion
40
, a dielectric substrate
42
, which is provided on package base portion
40
and which is disposed so that the end portion thereof is positioned within waveguide
41
, and a cover portion
43
, which is made from metal or the like and which closes the upper portion of package base portion
42
. A microstrip line
44
which serves to transmit the high frequency signal is provided on top of the dielectric substrate
42
.
A microstrip line-waveguide converter
45
, which is connected with the microstrip line
44
, and which serves to conduct conversion between the transmission mode of the microstrip line
44
and the transmission mode of the waveguide, is provided on top of the end portion of dielectric substrate
42
.
A sealing dielectric substrate
46
is applied to the lower portion of waveguide
41
, and by means of this, airtight sealing of the package is realized.
Furthermore,
FIG. 16
is a cross-sectional view showing the package for MIC which is disclosed in Japanese Patent Application, First Publication No. Sho 58-215802 (hereinbelow referred to as Conventional Example 2).
As shown in
FIG. 16
, the conventional MIC package is provided with package main body
50
comprising a metal such as copper or the like, a concave portion
51
which is formed in the central portion of this package main body
50
and which provides a carrier, waveguides
52
which are formed at both end portions of the main body
50
and which communicate with concave portion
51
, a cover
53
, which is attached by welding or the like to the upper portion of the package main body
50
, a microstrip line
54
for the terminal for high frequency input and output, an end of which projects within the waveguides
52
, and an airtight sealing plate
55
comprising an insulator material such as silica glass or the like, which is attached to the bottom portion of waveguides
52
.
Furthermore, when a portion or the entirety of waveguides
52
is filled with a dielectric material and sealed in an airtight manner, it is possible to make the waveguides
52
small, so that it is possible to achieve a reduction in size of the package.
The following problems were present in the conventional technology described above.
(1) In the integrated circuit package of Conventional Example 1, interface mismatching is produced at the portion of dielectric substrate
46
which is affixed to waveguide
41
, and the reflection coefficient becomes high, so that there is a large passage loss.
FIG. 17
is a graph showing a simulation of the passage loss when a conventional integrated circuit is employed. It can be seen from
FIG. 17
that the passage loss increases as the frequency increases in conventional integrated circuit packages. Accordingly, it is difficult to employ the integrated circuit package of Conventional Example 1 at millimeter band frequencies of 60 GHz or more.
In the MIC package of Conventional Example 2, as well, as in the package of Conventional Example 1, the interface characteristics are poor at airtight sealing plate
55
, and the passage loss increases. In order to prevent passage loss, attempts have been made to construct the airtight sealing plate
55
from a thin material having a low dielectric constant; however, the airtight sealing plate
55
is easily broken, so that there is a problem with the durability thereof.
(2) Dielectric substrate
46
or airtight sealing plate
55
are attached to the bottom portions of waveguides
41
and
52
in order to create an airtight seal, so that the effects caused by the adhesive employed for the affixing or the accuracy of attachment can be striking, and it is difficult to achieve optimal characteristics.
(3) The conversion of the transmission mode is conducted by the microstrip lines
44
and
54
which project in the form of antennae into waveguides
41
and
52
, so that it is not possible to employ broadband frequencies. For this reason, the uses are restricted.
SUMMARY OF THE INVENTION
The present invention is carried out to solve the problems described above; and it is as an object thereof to provide a microstrip line-waveguide conversion structure, and an integrated circuit package for high frequency signals employing such a conversion structure, and a manufacturing method therefor, which are capable of reducing the passage loss even when millimeter band frequencies are employed, in which the structure is simple, and which may be applied to broadband frequencies.
The microstrip line-waveguide conversion structure of the present invention has a dielectric substrate, and a microstrip line which is provided on the dielectric substrate and is provided with widened portions which are formed so as to broaden a conductor, wherein is provided a waveguide portion containing the widened portions on the dielectric substrate.
It is preferable that transmission mode converters formed so as to incline in the direction of the widened portions be provided in the vicinity of the widened portions of the microstrip line.
The high frequency signal transmitted is a signal in, for example, the millimeter waveband.
In the first integrated circuit package for high frequency signals of the present invention, an integrated circuit for high frequency signals which is provided on a base member, and a microstrip line which is provided with widened portions formed so as to widen a conductor, are covered from the upper portion thereof in an attached manner by a metal cover, and, at the point of contact between the metal cover and the widened portions provided in the microstrip line, a waveguide portion formed on a dielectric substrate is provided, and an airtight seal is formed.
It is preferable that transmission mode converters formed so as to incline in the direction of the widened portions be provided in the vicinity of the widened portions of the microstrip line.
The shape of the waveguide portion is determined by the width and thickness of the dielectric substrate.
The second integr
Lee Benny
NEC Corporation
Whitham Curtis & Christofferson, PC
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