JP2002057461A - Multilayered printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that conventionally crosswalk noise larger than that between signal wirings of a parallel wiring group is generated between feedthrough adjacent conductors for signals in a multilayer printed circuit board, having the parallel wiring group. SOLUTION: In the multilayered printed circuit board, a second insulating layer I2, having a second parallel wiring group L2 perpendicular to a first parallel wiring group L1, is laminated on a first insulating layer I1 having the first group L1. The first and second groups L1 and L2 are connected via a feedthrough conductor group T. The groups L1 and L2 respectively have signal wirings S1 and S2 and power wirings P1 and P2 or ground wirings G1 and G2. An auxiliary feedthrough conductor Ts, connected at one end to the wiring G1 interposed between conductors T1 for the signals and opened at he other end, is arranged between the conductors T1 for respectively connecting the two adjacent signal wirings S1 via the wiring G1 to corresponding signal wiring S2. Thus, crosswalks between the conductors T1 can be reduced effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board used for an electronic circuit board or the like, and more particularly to a wiring structure in a multilayer wiring board on which a semiconductor element operating at a high speed is mounted.

[0002]

2. Description of the Related Art Conventionally, in a multilayer wiring board on which a semiconductor element such as a semiconductor integrated circuit element is mounted and which is used for an electronic circuit board or the like, an insulating material made of ceramics such as alumina is used for forming a wiring conductor for internal wiring. Layers and wiring conductors made of a refractory metal such as tungsten (W) are alternately stacked to form a multilayer wiring board.

In a conventional multilayer wiring board, signal wirings of internal wiring wiring conductors usually have a strip line structure, and a so-called solid pattern is formed above and below wiring conductors formed as signal wirings via insulating layers. A ground (ground) layer or a power supply layer having a wide area of the shape was formed.

Further, with the increase in the speed of electric signals handled by the multilayer wiring board, the insulating layer is replaced with alumina ceramics having a relative dielectric constant of about 10, and a polyimide resin or epoxy resin having a relatively small relative dielectric constant of 3.5 to 5 is used. And a conductive layer for internal wiring made of copper (Cu) is formed on the insulating layer by using a thin film forming technique such as a vapor deposition method such as a vapor deposition method or a sputtering method. By forming a wiring conductor in a pattern and multiplying the insulating layer and the wiring conductor into layers, a multilayer wiring board having a high density, a high function and a high speed operation of a semiconductor element has been obtained.

On the other hand, the wiring structure of the internal wiring of the multilayer wiring board is designed to reduce the impedance of the wiring, reduce the crosstalk between signal wirings, etc. A structure has been proposed in which a group of parallel wirings is formed, which is multi-layered, and predetermined wirings in the wiring group of each layer are electrically connected to each other via through conductors such as via conductors and through-hole conductors.

In a multilayer wiring board having such parallel wiring groups, an electronic component such as a semiconductor element mounted on the multilayer wiring board is electrically connected to a mounting board on which the multilayer wiring board is mounted. Then, an appropriate wiring is selected from each parallel wiring group in the multilayer wiring board, and the connection between the wirings between different wiring layers is performed via a through conductor such as a via conductor.

[0007]

In the conventional multilayer wiring board, when the signal wirings of the upper and lower wiring layers are electrically connected to each other via the through conductor, a large number of signal wirings transmitting different high-frequency signals are connected to each other. The wiring circuit network is formed by being connected by the signal through conductors.

However, in the multilayer wiring board having the above-described orthogonal wiring groups, when the signal wirings are electrically connected to each other by the through-conductors between the upper and lower parallel wiring groups, the signal through-conductors are not used. When they are arranged close to each other, the electromagnetic coupling force between the adjacent signal through conductors increases, and as a result, crosstalk between the signal through conductors as compared with the signal wires in the parallel wiring group increases. However, there is a problem that the crosstalk noise increases.

The present invention has been devised in view of the above problems, and has as its object to electrically connect signal wires to each other by through conductors in upper and lower parallel wiring groups of alternately stacked parallel wiring groups. In such a case, by arranging a predetermined through conductor in the vicinity thereof, it is possible to reduce crosstalk between the signal through conductors and suppress occurrence of crosstalk noise, and to operate a high speed semiconductor integrated circuit element. Another object of the present invention is to provide a multilayer wiring board suitable for an electronic circuit board, a package, and the like on which the semiconductor element is mounted.

[0010]

According to the present invention, there is provided a multilayer wiring board comprising a second parallel wiring group orthogonal to the first parallel wiring group on a first insulating layer having the first parallel wiring group. A first insulating layer having a first insulating layer, a first insulating layer, a first insulating layer, and a second insulating layer. Each of the groups includes a plurality of signal wirings and a power supply wiring or a ground wiring adjacent to each signal wiring, and two parallel wiring groups adjacent to each other with the power supply wiring or the ground wiring interposed therebetween.
One end is electrically connected to the power supply wiring or the ground wiring interposed between the signal through conductors that electrically connect one of the signal wirings to the corresponding signal wiring of the other parallel wiring group. An auxiliary through conductor, which is electrically connected and the other end of which is open, is disposed between the first and second parallel wiring groups.

Further, in the multilayer wiring board according to the present invention, in the above structure, the size of the auxiliary through conductor is larger than that of the signal through conductor.

According to the multilayer wiring board of the present invention, two signal wirings of the first and second parallel wiring groups adjacent to each other with the power supply wiring or the ground wiring interposed therebetween in one of the parallel wiring groups. One end is electrically connected to the power supply wiring or the ground wiring interposed between the signal through conductors, which are electrically connected to the corresponding signal wirings of the other parallel wiring group. Since the auxiliary through conductor having the other end opened is disposed between the first and second parallel wiring groups, the auxiliary through conductor is electrically connected to the signal through conductors disposed between the signal through conductors. Since the electromagnetic coupling force between the signal through conductors is weakened by the non-auxiliary through conductors, the crosstalk between the signal through conductors can be reduced and the generation of crosstalk noise can be suppressed.

According to the multilayer wiring board of the present invention, when the signal wirings are electrically connected to each other by the signal through conductor between the upper and lower parallel wiring groups in the alternately stacked parallel wiring groups, By arranging an auxiliary through conductor open at the other end connected to the power supply wiring or the ground wiring of one of the parallel wiring groups in a predetermined positional relationship in the vicinity, crosstalk between these signal through conductors is reduced to reduce the crosstalk. A multilayer wiring board suitable for an electronic circuit board, a package, or the like on which a semiconductor element such as a semiconductor integrated circuit element operating at a high speed, which can suppress occurrence of talk noise, is provided.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a multilayer wiring board according to the present invention will be described in detail based on an embodiment shown in the accompanying drawings.

FIG. 1 shows an example of an embodiment of a laminated wiring body according to the multilayer wiring board of the present invention, and FIG.
3B is a plan view of a main part of the first insulating layer, and FIG. 3B is a plan view of a main part of the second insulating layer. FIG. 2 is a plan view of an essential part showing an example of an embodiment of a multilayer wiring board of the present invention including a laminated wiring body obtained by laminating them. Further, FIG.
FIG. 3 is a sectional view taken along line AA ′ of the multilayer wiring board shown in FIG.

In these figures, I1 to I3 are first to third insulating layers, respectively, and L1 and L2 are disposed substantially parallel to the upper surfaces of the first and second insulating layers I1 and I2, respectively. These are the first and second parallel wiring groups. The second parallel wiring group L2 is arranged such that each wiring conductor is orthogonal to the first parallel wiring group L1.

P1 and P2 are power supply wirings in the first and second parallel wiring groups L1 and L2, respectively, G1 and G2 are ground wirings in the first and second parallel wiring groups L1 and L2, respectively.
S2 indicates a signal wiring in the first and second parallel wiring groups L1 and L2, respectively.

T is a through conductor group that electrically connects the first parallel wiring group L1 and the second parallel wiring group L2 at a predetermined location, and T1 connects the signal wirings S1 and S2. The signal through conductor T2 indicates a power / ground through conductor that connects the power lines P1 and P2 or the ground lines G1 and G2.

As described above, in the multilayer wiring body of the multilayer wiring board of the present invention, the first parallel wiring group L1 including the signal wiring S1 and the power supply wiring P1 or the ground wiring G1 adjacent thereto is substantially in the first direction. A second parallel wiring group L2 including a signal wiring S2 and a power supply wiring P2 or a ground wiring G2 adjacent to the signal wiring S2 stacked in parallel and stacked thereon.
Are disposed substantially parallel to a second direction orthogonal to the first direction, and each of these wirings penetrates through the second insulating layer I2, and includes a signal through conductor group T1 and a power / ground through conductor. They are electrically connected by the group T2 to form a laminated wiring body.

According to such a stacked wiring body, since the first parallel wiring group L1 and the second parallel wiring group L2 are stacked so as to be orthogonal to each other, the parallel wiring groups L1 and L
Crosstalk noise between the two wirings can be reduced to a minimum.

The plurality of signal lines S1 and S2 arranged on the same plane may transmit different signals, respectively, and the plurality of power lines P1 and S1 arranged on the same plane may be used.
P2 may supply different powers.

I3 is laminated on the second insulating layer I2,
This is a third insulating layer to be a surface layer of the multilayer wiring board. The third insulating layer I3 is formed as needed. For example, when the second parallel wiring group L2 is provided in the second insulating layer I2, the third insulating layer I3 is not necessarily formed. .

In such a multilayer wiring board, for example, an MPU (Micro Processing Unit) / ASIC (A
pplication Specific Integrated Circuit) ・ DSP
A semiconductor device such as a semiconductor integrated circuit device such as a digital signal processor (Digital Signal Processor) is mounted. Then, it is used as a package for storing semiconductor elements, a substrate for mounting semiconductor elements, a so-called multi-chip module or multi-chip package on which a large number of semiconductor integrated circuit elements are mounted, a motherboard, or the like. These semiconductor elements are mounted on the surface of the multilayer wiring board by, for example, so-called bump electrodes, or are attached to a mounting portion by an adhesive, a brazing material, or the like, and are connected to the mounting portion via a bonding wire, for example, by a through conductor. It is electrically connected to the second parallel wiring group L2. A connection portion with an external electric circuit and a connection portion with a mounted semiconductor element are not shown.

The through conductor group T penetrates through the second insulating layer I2 and electrically connects the upper and lower wirings. Usually, a through-hole conductor or a via conductor is used, and the through conductor group T is used for connection. Formed at the location. A similar through conductor group is also used to electrically connect the wiring of each of the parallel wiring groups L1 and L2 to an electronic component or an external connection terminal attached to the surface of the multilayer wiring board.

In the multilayer wiring board of the present invention, as shown in FIG. 1 to FIG. 3, two parallel wiring groups, here, a first parallel wiring group L1, two adjacent wiring groups sandwiching the ground wiring G1 therebetween. The signal wiring S1 is sandwiched between the signal penetrating conductors T1 electrically connected to the corresponding signal wirings S2 of the other parallel wiring group, here, the second parallel wiring group L2, between these signal penetrating conductors T1. The auxiliary through conductor Ts, one end of which is connected to the ground wiring G1 and the other end of which is open,
Between the first and second parallel wiring groups L1 and L2, in this example, in the second insulating layer I2, they are arranged substantially parallel to the signal through conductor T1. Thereby, the electromagnetic coupling force between the adjacent signal through conductors T1 is weakened by the auxiliary through conductors Ts located therebetween, so that the crosstalk between the signal through conductors T1 is reduced and the signal through conductors T1 are reduced.
1 can significantly reduce crosstalk noise.

One end of the auxiliary through conductor Ts is electrically connected to the power supply wiring P1 if the two signal wirings S1 of the first parallel wiring group L1 are adjacent to each other across the power supply wiring P1. What should have been done. Further, the signal wiring S2, the ground wiring G2, and the power supply wiring P2 of the second parallel wiring group L2 may be provided in a similar configuration.

When the auxiliary through conductor Ts is provided in the multilayer wiring board of the present invention in this manner, the power supply wiring P1.
In order to reduce crosstalk efficiently, the position connected to P2 or the ground wirings G1 and G2 is on a straight line connecting between adjacent signal through conductors S1 or S2 or between these signal through conductors S1 or S2. It is preferable to dispose so that The position is determined in consideration of electrical characteristics based on dimensions, shapes and materials of the respective portions of the parallel wiring groups L1 and L2 and the respective through conductors T, electromagnetic characteristics with respect to high frequencies, and the like, and through signal conductors. T1
May be appropriately set in consideration of obtaining a desired characteristic impedance.

Further, the length of the auxiliary through conductor Ts is an object between the first and second parallel wiring groups L1 and L2 from the viewpoint of most effectively reducing the crosstalk between the signal through conductors T1. It is preferable that the length of the through-signal conductor T1 be about 1/10 to about the same. This length is about
If it is less than one-tenth, the electromagnetic coupling force between the signal through conductors T1 is hardly weakened, and the crosstalk cannot be sufficiently reduced, resulting in a crosstalk noise of 5%.
When the degree is less than the degree, the degree of reduction tends to be insufficient. On the other hand, if the length exceeds the length of the signal through conductor T1, the first and second parallel wiring groups L
There is a tendency that it is difficult to stably and accurately arrange between 1 and L2.

Further, the size (usually the thickness) of the auxiliary through conductor Ts depends on the magnitude of the electromagnetic coupling force between the signal through conductors T1 around the same thickness as the signal through conductor T1. The size may be increased (thick) or decreased (thin) as appropriate. Specifically, the size (thickness) of about 1/4 to about 3 times, preferably about 1/2 or more and about 2 times or less of the size (thickness) of the signal through conductor T1 is reduced. Just fine. If this size is less than about one-quarter, it tends to be difficult to stably and accurately arrange the auxiliary through conductor when configuring the auxiliary through conductor. On the other hand, when the size exceeds about three times, the possibility of short-circuiting with the adjacent wiring increases, and it tends to be difficult to increase the density of the wiring.

4 to 6 show FIGS. 1 to 3 respectively.
When the size of the auxiliary through conductor Ts is larger than that of the signal through conductor T1, as in another example of the embodiment of the multilayer wiring body according to the multilayer wiring board of the present invention shown in the same drawing as in FIG. In addition, since the crosstalk noise can be reduced and the electrical connection with the power supply wiring or the ground wiring electrically connected to the auxiliary through conductor, that is, the capacitance increases, stable power supply can be performed.

In the multilayer wiring board of the present invention, for example,
For example, the relative dielectric constant ε _rBut about 10 same invitations
Using a dielectric material, the thickness of the insulating layer is 254 μm,
The distance between conductors is 1.27mm, cross-sectional size is 0.1mm x 0.1m
When the configuration is made as m, as shown in FIG.
The auxiliary through conductor Ts is provided by arranging the signal through conductor T1 as shown in FIG.
If there is no crosstalk noise in the signal through conductor T1
Is 14.7 mV. On the other hand, as shown in FIG.
The auxiliary through conductor Ts is located between the signal through conductors T1.
The crossing of the signal through conductor T1
Talk noise can be reduced to 4.0 mV.

The above configuration is similar to the example shown in FIGS. 1 to 3 or FIGS. 4 to 6 below the first parallel wiring group L1 and above the second parallel wiring group L2. The present invention can also be applied to a case where the parallel wiring groups are stacked so as to be orthogonal to each other and are electrically connected to the parallel wiring groups by the through conductor group.

Further, with respect to the multilayer wiring board of the present invention,
On and under the first and second parallel wiring groups L1 and L2, multilayer wiring portions having various wiring structures can be stacked to form a multilayer wiring board. For example, a wiring structure having a structure in which parallel wiring groups are orthogonally stacked like a multilayer wiring body, a wiring structure having a strip line structure, and other specifications required for a multi-layer wiring substrate such as a microstrip line structure and a coplanar line structure. It can be appropriately selected and used according to the conditions.

Further, the first and second parallel wiring groups L1
A ground conductor layer having a function as an electromagnetic shield for EMI noise or the like may be provided above and below L2.

Further, for example, an electronic circuit may be formed by laminating a polyimide insulating layer and a conductor layer formed by vapor deposition of copper, such as a chip resistor, a thin film resistor, a coil inductor, a cross capacitor, a chip capacitor, and an electrolytic capacitor. It may be attached to form a semiconductor element storage package.

The shape of each of the insulating layers including the first to third insulating layers I1 to I3 is not limited to a substantially square shape as shown in a plan view of a main part, but is a rectangular shape. Or a shape such as a rhombus or a polygon.

The first and second parallel wiring groups L1.
L2 is not limited to those formed on the surfaces of the first and second insulating layers I1 and I2, and may be formed inside the respective insulating layers I1 and I2.

Further, in the example shown in FIG. 3 or FIG. 6, the third insulating layer I3 is not laminated, and the second parallel wiring group L
2 may be formed on the surface of the second insulating layer I2 to be exposed on the surface of the multilayer wiring board.

In the multilayer wiring board of the present invention, each of the first to third insulating layers I1 to I3 is made of an aluminum oxide sintered body or an aluminum nitride sintered body by, for example, a ceramic green sheet laminating method. Silicon carbide sintered body
Using inorganic insulating materials such as silicon nitride sintered body, mullite sintered body, glass ceramics, or organic insulating materials such as polyimide, epoxy resin, fluororesin, polynorbornene, benzocyclobutene, Alternatively, it is formed using an electrical insulating material such as a composite insulating material formed by bonding an inorganic insulating powder such as a ceramic powder with a thermosetting resin such as an epoxy resin.

If these insulating layers are made of, for example, an aluminum oxide sintered body, a suitable organic binder, a solvent, etc. are added to a raw material powder of aluminum oxide, silicon oxide, calcium oxide, magnesium oxide, etc. and mixed. A ceramic green sheet was obtained by forming the sheet into a sheet shape by employing a well-known doctor blade method, and thereafter, the ceramic green sheet was subjected to an appropriate punching process and each parallel wiring was formed. The group and each through conductor group and the metal paste to be the conductor layer are printed and applied in a predetermined pattern and laminated vertically,
Finally, the laminate is manufactured by firing at a temperature of about 1600 ° C. in a reducing atmosphere.

The thickness of these insulating layers is determined so as to satisfy the conditions such as mechanical strength and electric characteristics corresponding to the required specifications and ease of forming the through conductor group according to the characteristics of the material to be used. It is set appropriately.

The first and second parallel wiring groups L1.
L2 and other wiring layers, ground conductor layers GL, through conductor groups, and the like are made of metal powder metallized, for example, tungsten, molybdenum, molybdenum-manganese, copper, silver, silver-palladium, or copper, silver, nickel, chrome, titanium. -It is composed of a thin film of a metal material such as gold, niobium, or an alloy thereof.

For example, in the case of metallization of metal powder of tungsten, a metal paste obtained by adding and mixing an appropriate organic binder and solvent to the tungsten powder is printed in a predetermined pattern on a ceramic green sheet serving as an insulating layer. By applying and firing this together with the ceramic green sheet laminate, it is disposed on the upper surface of each insulating layer.

In the case of a thin film of a metal material, a metal layer is formed by, for example, a sputtering method, a vacuum evaporation method, or a plating method, and then a predetermined wiring pattern is formed by a photolithography method.

The widths and the intervals between the wirings of the first and second parallel wiring groups L1 and L2, or the through conductor group T
The shape, dimensions, arrangement position, etc. of the insulation layer I and the electrical characteristics corresponding to the required specifications depend on the characteristics of the material used.
It is set appropriately so as to satisfy conditions such as ease of disposition in 1.I2.

The thickness of each of the parallel wiring groups L1 and L2 is 1
It is preferably about 20 μm. This thickness is 1 μm
When the value is less than the above, the resistance of the wiring increases, and it tends to be difficult to provide a good power supply to the semiconductor element by the wiring group, secure a stable ground, and propagate a good signal.
On the other hand, if it exceeds 20 μm, the insulation layer laminated thereon may be insufficiently covered, resulting in poor insulation.

Each of the through conductors T1 and T2 of the through conductor group T and the auxiliary through conductor Ts may have a cross-sectional shape other than a circle, such as an ellipse, a rectangle such as a square or a rectangle, or any other shape. Is also good. The position and size are appropriately set according to the characteristics of the material to be used so as to satisfy conditions such as electrical characteristics corresponding to required specifications and easiness of formation and arrangement on the insulating layer.

For example, when the aluminum oxide sintered body is used for the insulating layer and the metallization of tungsten is used for the parallel wiring group, the thickness of the insulating layer is set to 200 μm.
By setting the line width of the wiring to 100 μm, the spacing between the wirings to 150 μm, and the size of the through conductor to 100 μm, the impedance of the signal wiring is set to 50Ω, and the electrical connection between the upper and lower parallel wiring groups is suppressed while suppressing the reflection of high-frequency signals. Can be connected to

It should be noted that the present invention is not limited to the above-described embodiments, and that various changes may be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the present invention has been described as a multilayer wiring board on which a semiconductor element is mounted. However, the present invention may be applied to a semiconductor element housing package for housing a semiconductor element or a multi-chip module. Further, an aluminum nitride-based sintered body / silicon carbide-based sintered body considering heat dissipation or a glass ceramics-based sintered body considering low dielectric constant may be used.

[0050]

According to the multilayer circuit board of the present invention, two signal wirings of the first and second parallel wiring groups adjacent to each other with the power supply wiring or the ground wiring interposed therebetween in one of the parallel wiring groups. One end is electrically connected to the power supply wiring or the ground wiring which is interposed between the signal through conductors for electrically connecting the signal wirings to the corresponding signal wirings of the other parallel wiring group. Since the auxiliary penetrating conductor which is connected and whose other end is open is disposed between the first and second parallel wiring groups, the signal penetrating conductor disposed between these signal penetrating conductors is electrically connected. Since the electromagnetic coupling force between the signal through conductors is weakened by the non-conductive auxiliary through conductors, crosstalk between the signal through conductors can be reduced and the generation of crosstalk noise can be suppressed.

Further, when the size of the auxiliary through conductor is made larger than that of the signal through conductor, electric coupling between the auxiliary through conductor and the power supply wiring or the ground wiring electrically connected to the auxiliary through conductor becomes large, that is, the capacitance becomes large. Power can be supplied.

Thus, according to the multilayer wiring board of the present invention, when the signal wirings are electrically connected by the signal through conductor between the upper and lower parallel wiring groups in the alternately stacked parallel wiring groups, By arranging an auxiliary through conductor open at the other end connected to the power supply wiring or the ground wiring of one of the parallel wiring groups in a predetermined positional relationship in the vicinity, crosstalk between these signal through conductors is reduced to reduce the crosstalk. A multilayer wiring board suitable for an electronic circuit board, a package, or the like on which a semiconductor element such as a semiconductor integrated circuit element operating at a high speed, which can suppress occurrence of talk noise, is provided.

[Brief description of the drawings]

FIGS. 1A and 1B show an example of an embodiment of a multilayer wiring body according to a multilayer wiring board of the present invention, wherein FIG. 1A shows a first insulating layer, and FIG. 1B shows a main part of a second insulating layer. FIG.

FIG. 2 is a main part plan view showing an example of an embodiment of a multilayer wiring board of the present invention.

FIG. 3 is a sectional view taken along line AA ′ of the multilayer wiring board shown in FIG. 2;

4A and 4B show another example of the embodiment of the multilayer wiring body according to the multilayer wiring board of the present invention, wherein FIG. 4A shows the first insulating layer, and FIG. 4B shows the second insulating layer. FIG.

FIG. 5 is a main part plan view showing another example of the embodiment of the multilayer wiring board of the present invention.

FIG. 6 is a sectional view taken along line AA ′ of the multilayer wiring board shown in FIG. 5;

[Explanation of symbols]

 ... I1 to I3... Insulating layer L1, L2... Parallel wiring group P1, P2... Power supply wiring G1, G2. ······ Thru-conductor group T1 ············································· Power supply / grounding through-conductor Ts ·····························

Claims (2)

[Claims] 1. A second insulating layer having a second parallel wiring group orthogonal to the first parallel wiring group is laminated on a first insulating layer having a first parallel wiring group. 1st and 2nd
And a plurality of signal wirings, and a power supply adjacent to each signal wiring. The first and second parallel wiring groups each include a plurality of signal wirings. A wiring or a ground wiring, and electrically connects two signal wirings adjacent to each other across the power supply wiring or the ground wiring in one of the parallel wiring groups to the corresponding signal wiring in the other parallel wiring group. Between the signal through conductors, an auxiliary through conductor having one end electrically connected to the power supply wiring or the ground wiring sandwiched between the signal through conductors and having the other end opened is connected to the first and second parallel through conductors. A multilayer wiring board, which is provided between wiring groups. 2. The multilayer wiring board according to claim 1, wherein the size of the auxiliary through conductor is larger than that of the signal through conductor.