Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – For high frequency device
Reexamination Certificate
2000-12-06
2002-12-03
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
For high frequency device
C257S691000
Reexamination Certificate
active
06489679
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high-frequency package and, more particularly, to a high-frequency package accommodating a semiconductor device and a high-frequency circuit being formed on the periphery of the device, for which high-frequency signals in a band of quasi-millimeter wavelengths and about 30-90 GHz frequencies are used.
2. Description of the Relevant Art
A high-frequency package is constructed by a semiconductor device mounting area and a high-frequency circuit on the periphery of the device, and both are formed on a dielectric substrate, being hermetically sealed with a ring-shaped frame and a lid to be jointed thereon. High-frequency signals are input and output through signal lines passing through the bottom of the ring-shaped frame.
FIGS. 1
a
and
1
b
are schematic diagrams showing a conventional high-frequency package of this type, and
FIG. 1
a
is a sectional side view, while
FIG. 1
b
is a sectional perspective view along line B—B of
FIG. 1
a.
A dielectric substrate
41
is formed almost in the shape of a rectangular parallelepiped board having a thickness T. A ground
42
is formed on the bottom surface
41
b
of the dielectric substrate
41
, while a ring-shaped frame
44
made of dielectrics is arranged in a prescribed place on the top surface
41
a
of the dielectric substrate
41
. A plurality of thin-film-like circuit strips
43
a
having a width of w
1
are formed in prescribed places on the top surface
41
a
in the inside region
44
d
of the frame
44
, while lead strips
43
b
similar to those (having a width of w
1
) are formed outside the frame
44
, facing the circuit strips
43
a
with the frame
44
between. One end portion of the circuit strip
43
a
and one end portion of the lead strip
43
b
are connected through a connecting strip
43
c
having a width of w
2
, which is buried under the frame
44
. A signal line
43
includes these circuit strip
43
a,
lead strip
43
b,
and connecting strip
43
c.
In order to equalize the characteristic impedance of a circuit including the connecting strip
43
c
and the frame
44
thereabout to those of the circuit strip
43
a
and the lead strip
43
b,
the width w
2
of the connecting strip
43
c
is set to be smaller than the widths w
1
of the circuit strip
43
a
and the lead strip
43
b.
In order to hold down the return loss in the signal line
43
and to make the insertion loss smaller, each characteristic impedance in the circuit strip
43
a,
lead strip
43
b
and connecting strip
43
c
is matched to one another.
A semiconductor device
45
is mounted almost in the center of the frame inside region
44
d
on the top surface
41
a,
and pads
45
a
of the semiconductor device
45
and the circuit strips
43
a
are connected through bonding wires
45
b.
A lid
46
is jointed onto the top of the frame
44
(hermetic sealing), and the frame inside region
44
d
on the dielectric substrate
41
is hermetically sealed thereby. A high-frequency package
40
of a microstrip line includes the dielectric substrate
41
, ground
42
, signal lines
43
, frame
44
, lid
46
, and associated parts.
High-frequency signals are input from the lead strip
43
b
of the signal line
43
through the connecting strip
43
c
and circuit strip
43
a
thereof and reach the semiconductor device
45
, while high-frequency signals emitted from the semiconductor device
45
are output from the lead strip
43
b
of the signal line
43
through the circuit strip
43
a
and connecting strip
43
c
thereof.
However, in the high-frequency package
40
having that construction, the width w
1
of the signal line
43
becomes narrow to w
2
in the connecting strip
43
c.
As a result, it is difficult to secure the dimensional precision of w
2
, and the resistance increases in the connecting strip
43
c,
so that the insertion loss tends to be large. Moreover, in the manufacture thereof, it is difficult to accurately fit together both ends of the connecting strip
43
c
and the inner and outer surfaces
44
b
and
44
c
of the frame
44
.
In order to cope with the problems, a high-frequency package has been proposed, wherein the portions of a frame, in which signal lines are buried, are formed to be thinner.
FIG. 2
is a perspective view diagrammatically showing the principal part of a conventional high-frequency package of this type, and reference numerals
41
and
42
in the figure represent a dielectric substrate and a ground similar to those shown in
FIG. 1. A
ring-shaped frame
54
made of dielectrics is arranged in a prescribed place on the top surface
41
a
of the dielectric substrate
41
, and an indented portion
54
b
is formed in a prescribed place of the frame
54
which a signal line
53
passes through. On the other hand, the thin-film-like signal line
53
having a width of w
1
is formed in a prescribed place on the top surface
41
a
of the dielectric substrate
41
. One end portion
53
a
of the signal line
53
is formed in the inside region
54
d
of the frame
54
, while the other end portion
53
b
of the signal line
53
is formed in the outside region
54
e
of the frame
54
. The middle portion of the signal line
53
is located in the vicinity of the indented portion
54
b
of the frame
54
.
Since the other constructions are almost the same as those shown in
FIG. 1
, no detailed descriptions thereof are given here. A high-frequency package includes these dielectric substrate
41
, ground
42
, signal lines
53
, frame
54
, and associated parts. High-frequency signals are input through the signal line
53
to a semiconductor device
45
(FIG.
1
), while high-frequency signals emitted from the semiconductor device
45
are output through the signal line
53
.
However, in the high-frequency package having that construction, the thickness e
1
of the indented portion
54
b
of the frame
54
need be set to be thin. This means that not only the manufacture thereof is difficult but the indented portion
54
b
thereof is especially low in strength.
In a high-frequency package of a microstrip line type shown in
FIG. 1
or
2
, when the semiconductor device
45
processes signals in a higher frequency band of such as millimeter or quasi-millimeter wavelengths, usually it causes a large connection loss of the semiconductor device
45
between the signal line
43
or
53
, and a large radiation loss in the signal line
43
or
53
as well.
In order to cope with the problems, recently, a high-frequency package including a so-called coplanar line arrangement has been proposed, wherein signal lines and grounds are formed alongside next to each other on a dielectric substrate, and a semiconductor device
45
is mounted thereon in a flip-chip manner.
FIG. 3
is a perspective view partly in section diagrammatically showing the principal part of a conventional high-frequency package of this type (Japanese Kokai No. 02-87701), and in the figure, reference numeral
61
represents a metal substrate. A ceramic plate
63
is fixed on the metal substrate
61
in the shape of a rectangular parallelepiped board, and laminates
64
made by laminating, for example, three conductor layers
64
a
and three ceramic layers
64
b
alternately are attached in one piece on both left and right sides with the ceramic plate
63
between. A dielectric substrate
62
having an external shape of a rectangular parallelepiped board includes the ceramic plate
63
, laminates
64
, and associated parts. Thin-film-like signal lines
65
having a width of w
1
are formed in prescribed places on the dielectric substrate
62
in the back-and-forth direction of the arrow in the figure, and grounds
66
are formed on both left and right sides of the signal lines
65
with gaps g interposed between.
Ceramic walls
68
are formed on the middle portions of the signal lines
65
and the grounds
66
thereabout in the right-and-left direction of the arrow in the figure, and laminates
69
made by laminating, for example, two conductor layers
69
a
and three ceramic layers
69
b
a
Araya Yoshihisa
Shiobara Masato
Tsukiyama Yoshio
Nelms David
Nguyen Thinh
Sumitomo Metal (SMI) Electronics Devices Inc.
Wenderoth , Lind & Ponack, L.L.P.
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