Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1999-05-04
2003-02-18
Paladini, Albert W. (Department: 2827)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S266000, C361S794000, C361S795000
Reexamination Certificate
active
06521843
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer printed circuit board. More to particularly, this invention relates to a multilayer printed circuit board which enables needless radiation of electromagnetic wave to be suppressed for preventing electromagnetic interference.
DESCRIPTION OF THE PRIOR ART
Structural example of conventional multilayer printed circuit board is shown in
FIGS. 1
,
2
,
3
, and
4
.
FIG. 1
is a sectional view showing one example of 4-layer printed circuit board by way of conventional example 1. In
FIG. 1
, the 4-layer printed circuit board is provided with a first signal wiring layer
111
, a ground layer
112
, a power supply layer
113
, and a second signal wiring layer
114
in order from above. Interlayer insulation materials
115
to
117
are formed between these wiring layers
111
to
114
. Further, a signal wiring
118
is arranged in the first signal wiring layer
111
, a signal wiring
119
is arranged in the second signal wiring layer
114
, a ground wiring
120
is arranged in the ground layer
112
, and a power supply wiring
121
is arranged in the power supply layer
113
.
In
FIG. 1
, if signal current flows through the signal wiring
118
, return circuit current is induced in the ground wiring
120
of the adjacent ground layer
112
through the interlayer insulation material
115
. A loop which is made by the signal wiring
118
and the ground wiring
120
is small, thus needless electromagnetic wave radiated from the loop is small.
FIG. 2
is a sectional view showing one example of conventional 6-layer printed circuit board by way of conventional example 2. The 6-layer printed circuit board is provided with a first signal wiring layer
131
, a second signal wiring layer
132
, a ground layer
133
, a power supply layer
134
, a third signal wiring layer
135
, and a fourth signal wiring layer
136
in order from above. Interlayer insulation materials
137
,
138
,
139
,
140
,
141
are formed between these wiring layers
131
to
136
. Further, a signal wiring
142
is arranged in the first signal wiring layer
131
, a signal wiring
143
is arranged in the second signal wiring layer
132
, a signal wiring
144
is arranged in the third signal wiring layer
135
, a signal wiring
145
is arranged in the fourth signal wiring layer
136
, a ground wiring
146
is arranged in the ground layer
133
, and a power supply wiring
147
is arranged in the power supply layer
134
.
In
FIG. 2
, if signal current flows through the signal wiring
143
, a return circuit current is induced in the ground wiring
146
of the adjacent ground layer
133
through the interlayer insulation material
138
. A loop which is made by the signal wiring
143
and the ground wiring
146
is small, thus needless electro-magnetic wave radiated from the loop is small.
FIG. 3
is a sectional view showing another example of 6-layer printed circuit board of conventional example 3. The 6-layer printed circuit board is provided with a first signal wiring layer
151
, a ground layer
152
, a second signal wiring layer
153
, a third signal wiring layer
154
, a power supply layer
155
, and a fourth signal wiring layer
156
. Respective interlayer insulation materials
157
,
158
,
159
,
160
, and
161
are formed between these wiring layers
151
to
156
. Further, a signal wiring
162
is arranged in the first signal wiring layer
151
, a signal wiring
163
is arranged in the second signal wiring layer
153
, a signal wiring
164
is arranged in the third signal wiring layer
154
, a signal wiring
165
is arranged in the fourth signal wiring layer
156
, a ground wiring
166
is arranged in the ground layer
152
, and a power supply wiring
167
is arranged in the power supply layer
155
.
In
FIG. 3
, if signal current flows through the signal wiring
162
or
163
, a return circuit current is induced in the ground wiring
166
of the adjacent ground layer
152
through the interlayer insulation material
157
or
158
. A loop which is made by the signal wiring
162
or
163
and the ground wiring
166
is small, thus needless electro-magnetic wave radiated from the loop is small.
FIG. 4
is a sectional view showing one example of 8-layer printed circuit board of conventional example 4. The 8-layer printed circuit board is provided with a first signal wiring layer
181
, a second signal wiring layer
182
, a ground layer
183
, a third signal wiring layer
184
, a fourth signal wiring layer
185
, a power supply layer
186
, a fifth signal wiring layer
187
, and a sixth signal wiring layer
188
in order from above. Respective interlayer insulation materials
189
,
190
,
191
,
192
,
193
,
194
, and
195
are formed between these wiring layers
181
to
188
. Further, a signal wiring
196
is arranged in the first signal wiring layer
181
, a signal wiring
197
is arranged in the second signal wiring layer
182
, a signal wiring
198
is arranged in the third signal wiring layer
184
, a signal wiring
199
is arranged in the fourth signal wiring layer
185
, a signal wiring
200
is arranged in the fifth signal wiring layer
187
, a signal wiring
201
is arranged in the sixth signal wiring layer
188
, a ground wiring
202
is arranged in the ground layer
183
, and a power supply wiring
203
is arranged in the power supply layer
186
.
In
FIG. 4
, if signal current flows through the signal wiring
197
or
198
, a return circuit current is induced in the ground wiring
202
of the adjacent ground layer
183
through the interlayer
190
or
191
. A loop which is made by the signal wiring
197
or
198
and the ground wiring
202
is small, thus needless electro-magnetic wave radiated from the loop is small.
However, above-described respective conventional examples include following problems.
If signal current flows through the signal wiring
119
shown in above conventional example 1, the return circuit current is not induced in the power supply wiring
121
of the adjacent power supply layer
113
through the interlayer insulation material
117
, but the return circuit current is induced anywhere distant ground. For this reason, the loop which is made by the signal wiring
119
and anywhere distant ground to which the return circuit current is induced becomes large. Furthermore, in the same manner that~the signal wiring
111
is connected to the signal wiring
114
by a through hole
122
, the return circuit current is induced anywhere distant ground, thus the loop which is made by successive signal wiring
111
, through hole
122
, and signal wiring
114
and anywhere distant ground becomes large, there is the problem that needless electro-magnetic wave radiated from the large loop becomes large.
If signal current flows through the signal wiring
142
, the signal wiring
144
, or the signal wiring
145
shown in the above conventional example 2, the return circuit current is not induced in the signal wiring
143
of the signal wiring layer
132
which is arranged adjacently through each interlayer insulation material
137
,
140
, or
141
, further the return circuit current is not induced in the power supply
147
of the power supply layer
134
, furthermore, the return circuit current is not induced the signal wiring
144
of the signal wiring layer
135
, but the return circuit current is induced anywhere in the distant ground. For that reason, the loop which is made by the signal wiring
142
,
144
, or
145
and anywhere distant ground to which the return circuit current is induced becomes large. In the same manner when at least more than two of the signal wiring
142
,
143
,
144
, and
145
are connected by the through hole
148
, the return circuit current is induced anywhere in the distant ground. The loop which is made by at least more than two of the successive signal wiring
142
,
143
,
144
, and
145
and the through hole
148
, and anywhere distant ground becomes large, thus there is the problem that needless electro-magnetic wave radiated from these loops becomes large.
If signal current flows throug
Alcalá José H.
Paladini Albert W.
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