Mounting structure for semiconductor device

Details Mounting structure for semiconductor device Mounting structure for semiconductor device

1998-12-29

2001-11-27

Paladini, Albert W. (Department: 2841)

Electricity: conductors and insulators

Conduits, cables or conductors

Combined

C174S125100, C257S661000, C257S700000, C257S726000, C505S220000

Reexamination Certificate

active

06323426

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mounting structure for a superconductor device, and more particularly to a mounting structure for a high temperature superconductor device housed in a closed vacuum chamber and operated at a low temperature.
2. Description of the Related Art
There have so far been proposed a wide variety of superconductor devices, especially high temperature superconductor (hereinlater referred to simply as “HTS”) devices, preferably utilized for an integrated circuit, a filter, an amplifier and so forth. This type of superconductor device generally comprises a dielectric substrate and superconducting thin film layers deposited on both of surfaces of the dielectric substrate by a physical vapor deposition method, e.g., a sputtering method or a reactive vapor deposition method. Each of the superconducting thin film layers is made of a ceramics system, such as an yttrium, barium, and copper oxide system (hereinlater referred to simply as a “YBaCuO system”) of the HTS.
The superconductor has an extremely low electric resistance below a critical temperature thereby causing superconductive phenomena. The superconductor has therefore an advantage over a normal metal conductor in reducing transmission loss of signals.
Typical superconductor device is however required to be housed in a closed vacuum chamber at a low pressure of 2×10
−2
Pa or less and cooled at a low temperature of 80 K in order to cause the aforesaid superconductive phenomena. The superconductor device should therefore be contained in a device holding apparatus
1
as shown in
FIG. 13
to keep the above pressure and temperature.
As shown in
FIG. 13
, the device holding apparatus
1
comprises a housing
2
formed with a closed vacuum chamber and a cooling device
3
. The cooling device
3
has a cold head
3
a
for placing the superconductor device
4
thereon and a cold finger
3
b
for holding the cold head
3
a
at a predetermined low temperature to cool the superconductor device
4
. The superconductor device
4
and the cooling device
3
are housed in the closed vacuum chamber. The cold finger
3
b
may comprise a coolant reservoir (not shown) for reserving a liquid helium or a liquid nitrogen, or another type of cooling device (not shown), such as a Stirling cycle cooler or a pulse tube type of cooler.
The device holding apparatus
1
further comprises an input connector
5
electrically connected to the superconductor device
4
through a signal inputting line
5
a
and an output connector
6
electrically connected to the superconductor device
4
through a signal outputting line
6
a.
The input and output connectors
5
and
6
are further electrically connected to external devices (not shown) outside of the device holding apparatus
1
. The superconductor device
4
can thus transmit a signal from and to the external devices through the input and output connectors
5
and
6
.
Referring to
FIGS. 14 and 15
of the drawings, there is shown a conventional mounting structure
90
for the superconductor device
4
shown in FIG.
13
. In this example, the superconductor device
4
is a planer band-pass filter
91
. The filter
91
is adapted to have a signal inputted from a first external device (not shown in the drawings) to output a second external device (not shown).
In this example, the filter
91
comprises a dielectric substrate
92
having first and second surfaces
92
a
and
92
b
diametrically opposite to each other. The first surface
92
a
of the dielectric substrate
92
is shown in
FIG. 15
as being an upper side surface, while the second surface
92
b
of the dielectric substrate
92
is shown in
FIG. 15
as being a lower side surface. The dielectric substrate
92
is made of a MgO.
The filter
91
further comprises a circuit layer
93
having a pattern of circuit lines made of a superconducting thin film and deposited on the first surface
92
a
of the dielectric substrate
92
. The superconducting thin film is made of a ceramics system, such as a YBaCuO system, of the HTS.
The filter
91
comprises a ground layer, not shown in the drawings, consisting of a superconducting thin film layer and a metal layer. The superconducting thin film layer of the ground layer is made of a YBaCuO system of the HTS and deposited on the second surface
92
b
of the dielectric substrate
92
. The metal layer of the ground layer is deposited on the superconducting thin film layer of the ground layer.
The conventional mounting structure
90
as shown in
FIGS. 14 and 15
comprises a device holder
94
, a plurality of fastening parts
95
, input and output connectors
96
a
and
96
b,
and an adhesive layer
97
.
The device holder
94
has a base surface
94
a
and is adapted to hold the filter
91
thereon. The device holder
94
is grounded where the base surface
94
a
of the device holder
94
and the ground layer of the filter
91
are electrically connected with each other. As shown in
FIG. 15
, the base surface
94
a
is formed on an upper side surface of the device holder
94
into a smoothed flat plane. The base surface
94
a
of the device holder
94
is made of a conductive material selected from among the group consisting of copper and aluminum and covered with a nickel and gold.
The input connector
96
a
is electrically connected to the filter
91
and the first external device through the input connector
5
shown in
FIG. 13
to allow the signal to be inputted from the first external device to the filter
91
. The output connector
96
b
is electrically connected to the filter
91
and the second external device through the output connector
6
shown in
FIG. 13
to allow the signal to be outputted from the filter
91
to the second external device. The filter
91
can thus transmit the signal from and to the first and second external devices outside of the device holding apparatus
1
.
The adhesive layer
97
intervenes between the ground layer of the filter
91
and the device holder
94
. The adhesive layer
97
has a first surface
97
a
facing the ground layer of the filter
91
and a second surface
97
b
facing the base surface
94
a
of the device holder
94
. In this example, the adhesive layer
97
is made of an indium foil covering a whole area of the ground layer of the filter
91
therewith.
The fastening parts
95
are operated to fasten the filter
91
on the device holder
94
, so that the first surface
97
a
of the adhesive layer
97
can be held in contact with the ground layer of the filter
91
and the second surface
97
b
of the adhesive layer
97
can be also held in contact with the base surface
94
a
of the device holder
94
. Each of the fastening parts
95
includes a pressing member
95
a
and a clamp screw
95
b
screwed into the device holder
94
to secure the pressing member
95
a
to the device holder
94
.
As shown in
FIG. 14
, the filter
91
has a circuit portion on which there is the circuit layer
93
and a peripheral portion on which there is no circuit layer. In this example, the fastening parts
95
are arranged along the peripheral portion of the device holder
94
at eight points to secure the filter
91
at its peripheral portion on the device holder
94
as shown in FIG.
14
.
Two of the eight points are especially positioned at the places adjacent to the input and output connectors
96
a
and
96
b
in order to ensure that the input and output of the filter
91
are securely grounded. Other than the above two points are spaced apart from each other at predetermined intervals in order to prevent the signal in a high frequency from leaking from the ground layer of the filter
91
. From this point of view, each of intervals of these positions may be assumed to be equal to or less than a half wavelength &lgr;/2 of the band-pass frequency of the filter
91
. In this example, the filter
91
has the half wavelength &lgr;/2 of 150 mm as the band-pass frequency is about 1 GHz. Therefore, the fastening parts
95
may be spaced apart from each other at the intervals of 150

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