Wave transmission lines and networks – Long line elements and components – Connectors and interconnections
Reexamination Certificate
2000-08-10
2002-12-31
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Long line elements and components
Connectors and interconnections
C333S238000
Reexamination Certificate
active
06501352
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a high frequency wiring board provided with a high frequency transmission line having a signal conductor line and a grounding layer formed parallel to the signal conductor line through a dialectic board, and its connecting structure. More particularly, the present invention relates to a high frequency wiring board suitable for a semiconductor device containing package, a multi-layer wiring board, or the like which carries a high frequency semiconductor device in a millimeter wave region having a frequency of not less than 30 GHz (and further, not less than 50 GHz) and its connecting structure.
2. Description of Related Art
As radio waves used for information transmission, radio waves in a microwave region having a frequency of 1 to 30 GHz have been conventionally used. In recent years, we have entered upon the sophisticated information year. Therefore, we have examined the use of a millimeter wave region having a frequency of 30 to 300 GHz. For example, application systems using radio waves in a millimeter wave region, for example, a high speed radio data communication system (radio LAN (Local Area Network)) in an office have been also proposed.
As a wiring board such as a package containing or carrying a high frequency semiconductor device (hereinafter merely referred to as a high frequency device) used for such application systems, a so-called metal package has been conventionally used. The metal package has a structure in which a connecting board made of ceramics is joined to a metal frame in order to minimize the transmission loss of a high frequency signal.
FIG. 16A
is a plan view showing a mounting structure in which a high frequency device is contained in a conventional metal package and is mounted on an external circuit board, and
FIG. 16B
is a cross-sectional view of the mounting structure. In
FIG. 16A
, a cover is omitted.
A metal package
33
comprises a metal board
31
and a cover
32
. A connecting board
36
in which a signal conductor line
35
is formed on a ceramic board
34
is mounted on a part of the metal package
33
. The signal conductor line
35
is electrically connected to a high frequency device
37
(indicated by hatching) carried in the metal package
33
by a ribbon or the like.
The metal package
33
is fixed to the surface of a base board
38
(indicated by hatching) by screws
39
or the like. A circuit board
42
in which a signal conductor line
41
is formed on the surface of a dielectric board
40
is provided on the surface of the base board
38
. The signal conductor line
41
is electrically connected to the signal conductor line
35
in the connecting board
36
by a ribbon, a wire, or the like.
The assembly of such a metal package is complicated. Accordingly, there have been difficulties in mass production cost reduction at the time of fabricating a module have been a problem.
In order to solve this problem, it has been proposed that a signal conductor line is pulled out to the reverse surface of the package using a through hole conductor or the like from the inside of the dielectric board. That is, a connecting terminal portion is formed at a terminal end of the signal conductor line in the form of a through hole. The package is soldered to and surface-mounted on a high frequency circuit formed on the surface of another dielectric board by soldering reflow.
FIGS. 17
,
18
A,
18
B, and
18
C are illustrations for explaining the structure of a high frequency package using such a through hole conductor. As illustrated in the schematic cross-sectional view of
FIG. 17
, a dielectric board
51
and a cover
52
form a cavity in a high frequency package
50
, and a high frequency device
53
is contained in the cavity. A signal conductor line
54
having its one end connected to the high frequency device
53
by a ribbon or the like is formed on the surface of the dielectric board
51
. A grounding layer
55
(indicated by hatching) having a pattern shown in
FIG. 18A
is formed inside the dielectric board
51
.
The other end of the signal conductor line
54
is connected to a through hole conductor
56
formed upon penetrating the dielectric board
51
so as not to come into contact with the grounding layer
55
. The through hole conductor
56
is connected to a signal conductor line
57
formed on the reverse surface of the dielectric board
51
. Consequently, the signal conductor line
54
is electrically connected to the signal conductor line
57
through the through hole conductor
56
.
A pair of connecting grounding conductors
58
(indicated by hatching) is provided with spacing on both sides of an end of the signal conductor line
57
(indicated by hatching), as shown in
FIG. 18B
, on the reverse surface of the dielectric board
51
. The grounding conductors
58
are electrically connected to the grounding layer
55
inside the dielectric board
51
, respectively, by viahole conductors
59
.
It is considered that when the viahole conductors
59
are formed near an end side surface a
50
of the dielectric board
51
, a portion between the viahole conductor
59
and the dielectric board
51
is liable to be cracked, for example. Generally, the viahole conductor
59
is formed at a position spaced not less than 2 mm apart from the end side surface a
50
of the dielectric board
51
from the viewpoint of processability of a viahole by a micro-drill or the like.
The spacing between the viahole conductor
59
and the signal conductor line
57
is generally set to not less than 1 mm such that solders are not brought into contact with each other and short-circuited by making connection using the solders. That is, the spacing is approximately 0.5 times the signal wavelength of a high frequency signal in the dielectric board
51
composed of alumina (having a dielectric constant of 8.9) ceramics, for example, when a high frequency signal having a frequency of 50 GHz is transmitted. In this construction, however, the transmission loss of the high frequency signal is large from the following reasons, and the signal cannot, in some cases, be transmitted.
In the above-mentioned construction, a connecting terminal portion is constituted by the dielectric board
51
, the signal conductor line
57
, the grounding layer
55
, the pair of connecting grounding conductors
58
, and the viahole conductor
59
. The connecting terminal portion is generally designed such that the impedance, in a cross section perpendicular to the direction of signal transmission, of the connecting terminal portion coincides with the impedance, in a cross section perpendicular to the direction of signal transmission, of a high frequency transmission line in order to diminish the reflection of the high frequency signal from the high frequency transmission line. In this case, however, the transmission loss of the high frequency signal is large from the following reasons, and the signal cannot, in some cases, be transmitted.
On the other hand, a grounding layer
61
is formed, as shown in
FIG. 17
, inside an external circuit board
60
on which the package
50
is mounted. A signal conductor line
62
(indicated by hatching) is formed, as shown in
FIG. 18C
, on the surface of the external circuit board
60
. In a connecting portion with the package
50
, connecting grounding conductors
63
(indicated by hatching) are formed with spacing on both sides of the signal conductor line
62
. The connecting grounding conductors
63
are electrically connected to each other by a grounding layer
61
and viahole conductors
64
.
The package
50
is mounted on the surface of the external circuit board
60
by electrically connecting the signal conductor lines
57
and
62
and electrically connecting the connecting grounding conductors
58
and
63
, respectively, using solders
65
such as solder.
The package
50
can be thus collectively connected mechanically and electrically to the external circuit board
60
by reflow or the like. Consequently, the package
50
is more advantag
Kitazawa Kenji
Koriyama Shin-ichi
Minamiue Hidehiro
Chang Joseph
Hogan & Hartson LLP
Kyocera Corporation
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