Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-03-08
2002-07-09
Martin, David S. (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S792000, C361S794000, C361S795000
Reexamination Certificate
active
06418032
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printed wiring board, and more particularly to a multi-layered printed wiring board having, inside of a substrate, a power source layer (power source layers) for supplying electric power to a semiconductor device.
2. Description of the Related Art
Conventionally, undesirable electromagnetic wave noise generated inside an electric or electronic device or external noise entering from the outside into an electric or electronic device has been a serious problem for electric and electronic devices. For this reason, electromagnetic compatibility (EMC) design is necessary in order to prevent undesirable electromagnetic wave noise from being generated inside the electric and electronic devices and to secure strength against external noise.
In recent electric and electronic devices, digitization of their electronic circuits and acceleration of the processing speed have been achieved. Accompanying this trend, electromagnetic noise has also increased rapidly. Further, due to the rapid increase in use of cellular phones, external noise has also increased. For this reason, EMC design has becomes technically difficult.
Particularly, a source of electromagnetic wave noise recently considered to be an important problem is noise current, which flows into a power source layer inside a substrate from a power supply circuit for supplying electric power to the semiconductor device when switching the semiconductor device which is disposed on the substrate.
According to Japanese Patent Application Laid Open (JP-A) No. 5-13909, a circuit board having a main power plane, a ground system, a very large scale integrated device and a sub-power plane has been proposed in order to suppress such noise current. As shown in
FIG. 12
, a main power plane
60
and a sub-power plane
62
, which is physically separated from the main power plane
60
and which is supplied with electric power from the main power plane
60
through a filter
64
, are provided as power source layers. The sub-power plane
62
is disposed just below a very large scale integrated device
70
and supplies electric power to the very large scale integrated device
70
.
In the same way as the aforementioned JP-A No. 5-13909, in the multi-layered printed wiring board proposed in JP-A No. 7-45962 which has a power source layer and a ground layer as the inner layers, the power source layer region, which is a connecting region of mounted components, and the ground layer region are separated and isolated from each other so as to prevent noise from being spread around.
However, although these prior art are effective for reducing radiation of low-frequency noise of not more than around 500 MHz which is generated from a circuit substrate when supplying electric power to the semiconductor device, it has been found that the radiation of high-frequency noise of about 1 GHz is great, or cannot be reduced.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a printed wiring board capable of suppressing not only radiation of low-frequency noise but also radiation of high-frequency noise, so that undesirable radiation noise which is newly generated can be kept to a low level, thereby reducing noise to a large extent overall.
To achieve the above object, according to a first aspect of the invention, there is provided a printed wiring board for supplying electric power from an external power source to a semiconductor device, wherein the semiconductor device has a plurality of input power supply terminals for inputting substantially equal voltages to the semiconductor device, the printed wiring board comprising:
(a) a plurality of layers, the layers including:
(i) a mounting face having a plurality of electrical terminals, the mounting face being adapted for mounting the semiconductor device thereto with the plurality of semiconductor device power supply terminals electrically connected to the mounting face electrical terminals; and
(ii) another layer having a first power source region adapted for connection to the external power source; and
(b) a second power source region having an outer configuration smaller than an outer configuration of the semiconductor device, electrically insulated from the first power source region except through an electrical connection through a filter, and electrically connected to the mounting face electrical terminals for supplying electrical power received from the first power source region through the filter, to the semiconductor device.
According to the first aspect of the present invention, the second power source region for supplying electric power to a semiconductor device having plural input power supply terminals, to which the same voltages are inputted, is provided independently of the first power source region. As a result, low-frequency noise components of electric power supplied from the outside can be reduced, further, because the outer configuration of the second power source region is smaller than the outer configuration of a device to be mounted on the mounting face, high-frequency noise radiated from the second power source region can be suppressed to a low level.
Therefore, the radiation noise on the whole can be reduced to an extremely low level. The semiconductor device may be, for example, an integrated circuit component such as an LSI or a ULSI. The “semiconductor device having plural input power supply terminals to which the same voltages are inputted” in the present invention means a semiconductor device having a set of plural input power supply terminals or plural sets of the plural input power supply terminals.
An effect of the present invention arises because the second power source region is smaller than an outer configuration of the semiconductor device. If the semiconductor device to be mounted is an integrated circuit component having a semiconductor chip or a die incorporating an integrated circuit, it is preferable that the second power source region is substantially as large as an area of the semiconductor chip contained in the integrated circuit component. Further, the second power source region may be rectangular, or may be a shape having roundness such as an oval, a circle or a rectangle having rounded corners. A shape having roundness can reduce radiation of noise correspondingly to the absence of angular corners.
Further, a single second power source region may be provided, or plural second power source region may be provided. Namely, one second power source region may be provided so as to correspond to one semiconductor device mounted on the mounting surface, or plural second power source regions may be provided so as to correspond to one semiconductor device mounted on the mounting surface.
For example, if plural function cells such as transistors or diodes are provided on a semiconductor chip within a semiconductor integrated circuit component selling as a semiconductor component, plural second power source regions can be provided electrically independently of one another such that one second power source region corresponds to one function cell or to plural function cells. Further, the second power source region for supplying electric power for the I/O of the semiconductor device and the second power source region for supplying electric power for the core may be provided separately.
Further, the first power source region and the second power source region may be formed on separate layers or on the same layer. If the first power source region and the second power source region are formed on the same layer, the effect of radiation noise reduction is more considerable than when they are formed on separate layers.
If the first power source region and the second power source region are formed on the same layer, the first power source region and the second power source region may be provided so as to be side by side, or the first power source region may be provided with an opening and then the second power source region may be provided within the opening such that it is not in direct
Hirata Masayuki
Ueno Osamu
Fuji 'Xerox Co., Ltd.
Levi Dameon E.
Martin David S.
Oliff & Berridg,e PLC
LandOfFree
Printed wiring board does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Printed wiring board, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Printed wiring board will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2898115