Wave transmission lines and networks – Long line elements and components – Strip type
Reexamination Certificate
2002-03-26
2004-08-24
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Long line elements and components
Strip type
C257S728000
Reexamination Certificate
active
06781488
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a connected construction of a high-frequency package and a wiring board and, more particularly, to a connected construction of a high-frequency package and a wiring board wherein the high-frequency package and the wiring board can be electrically connected without degrading the transmission characteristic of high-frequency signals of 20 GHz and higher.
2. Description of the Relevant Art
A conventional high-frequency package is constructed by a semiconductor device mounting area and a high-frequency circuit on the periphery of the device, both of which are formed on a dielectric substrate, being sealed with a ring-shaped frame and a lid to be arranged thereon. A semiconductor device mounted on the semiconductor device mounting area is connected to signal lines formed so as to pass through the sidewall portion of the frame. Connecting the signal lines of the high-frequency package with the semiconductor device mounted thereon to signal lines of a wiring board makes it possible to input and output high-frequency signals from and to the outside of the package. In that connection between the high-frequency package and the wiring board, the formation of a package construction and signal lines, which make it possible to input and output high-frequency signals without degrading the high-frequency signal characteristics, is required.
FIGS.
18
(
a
) and
18
(
b
) are schematic diagrams showing a conventional connected construction of a high-frequency package and a wiring board of this type, and FIG.
18
(
a
) is a sectional side view, while FIG.
18
(
b
) is a sectional perspective view along line B—B of FIG.
18
(
a
).
A dielectric substrate
41
is formed almost in the shape of a rectangular parallelepiped board having a thickness of 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 formed 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 dielectric substrate top surface
41
a
in the frame inside region
44
d,
while lead strips
43
b
similar to those (having a width of w
1
) are formed in the outside region
44
e,
facing the circuit strips
43
a
with the frame
44
between. One end portions of the circuit strips
43
a
and one end portions of the lead strips
43
b
are connected through connecting strips
43
c
having a width of w
2
, which are buried within a wall portion
44
a
of the frame
44
. A signal line
43
comprises these circuit strip
43
a,
lead strip
43
b,
and connecting strip
43
c.
In order to equalize the characteristic impedance of a circuit comprising the connecting strip
43
c
and the wall portion
44
a
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 transmission 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 dielectric substrate top surface
41
a
in the frame inside region
44
d,
and pads
45
a
of the semiconductor device
45
and the other end portions of the circuit strips
43
a
are connected through bonding wires
45
b.
A lid
46
is joined onto the top of the frame
44
(hermetic sealing), and the frame inside region
44
d
on the dielectric substrate
41
is sealed thereby. A high-frequency package
40
of a microstrip line type comprises these dielectric substrate
41
, ground
42
, signal lines
43
, frame
44
, lid
46
, and associated parts.
The lead strip
43
b
of the signal line
43
of the high-frequency package
40
is electrically connected to one end of a signal line
52
formed on a wiring board
50
through an outer lead terminal
53
.
In that connected construction, high-frequency signals (not shown) are input from the signal line
52
of the wiring board
50
through the outer lead terminal
53
, the lead strip
43
b,
connecting strip
43
c
and circuit strip
43
a
of the signal line
43
of the high-frequency package
40
, and associated parts, and reach the semiconductor device
45
, while high-frequency signals emitted from the semiconductor device
45
of the high-frequency package
40
are output from the circuit strip
43
a
of the signal line
43
through the connecting strip
43
c
and lead strip
43
b
thereof, and the outer lead terminal
53
to the signal line
52
of the wiring board
50
.
However, in the connected construction of the high-frequency package
40
and the wiring board
50
as stated above, it is extremely difficult to equalize the characteristic impedance in the outer lead terminal
53
to those in the signal lines
43
and
52
. Therefore, the characteristic impedance mismatch becomes large between the outer lead terminal
53
and the signal line
52
on the wiring board
50
as well as between the outer lead terminal
53
and the lead strip
43
b
of the signal line
43
of the high-frequency package
40
. As a result, the signal reflection caused by the characteristic impedance mismatch at the junction between the outer lead terminal
53
and the signal line
52
on the wiring board
50
, and that at the junction between the outer lead terminal
53
and the signal line
43
of the high-frequency package
40
, becomes large. In order to cope with the problem, a connected construction has been proposed, wherein signal lines of a high-frequency package and signal lines of a wiring board are directly connected without using outer lead terminals for connecting the high-frequency package to the wiring board, through improvements in the interconnection structure of the signal lines of the high-frequency package and the like.
In Japanese Kokai No. 2000-164764, it has been disclosed that a high-frequency package and a wiring board can be connected without degrading the transmission characteristic of high-frequency signals by forming connecting pads on both sides of each connected portion of signal lines of the high-frequency package and those of the wiring board, both having transmission lines of a transmission mode of microstrip, and arranging connecting conductive vias (through hole conductors) to connect a ground layer formed within the high-frequency package to a ground layer formed within the wiring board through the connecting pads.
FIG. 19
is a sectional side view showing the connected construction of a high-frequency package and a wiring board described in the Japanese Kokai No. 2000-164764. FIGS.
20
(
a
)-(
c
) are schematic diagrams showing the principal part of the connected construction of a high-frequency package and a wiring board shown in
FIG. 19
, wherein FIG.
20
(
a
) is a top plan view of the high-frequency package, FIG.
20
(
b
) is a bottom plan view thereof, and FIG.
20
(
c
) is a top plan view of the wiring board.
Reference numeral
61
in the figure represents a dielectric substrate made of ceramics or the like. A cap-shaped lid
62
is joined to a prescribed place on the top surface of the dielectric substrate
61
through a seal portion
63
. A plurality of signal lines
64
are formed in prescribed places on the top surface of the dielectric substrate
61
in the inside region
62
a
of the lid
62
, and each one end of the signal lines
64
is connected to a semiconductor device
65
.
Within the dielectric substrate
61
, a ground layer
66
is formed across the dielectric substrate
61
except for slots
66
a,
and a microstrip line as a third high-frequency transmission line C is formed from the ground layer
66
and the signal line
64
.
In addition, signal lines
67
are formed in prescribed places on the bottom surface of the dielectric subs
Shiobara Masato
Tsukiyama Yoshio
Glenn Kimberly
Lee Benny
Sumitomo Metal (SMI) Electronics Devices Inc.
Wenderoth , Lind & Ponack, L.L.P.
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