JPH11163531A - Multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the effect of multiple reflection in a branch wiring for high speed signal transmission by forming the main wiring of a wiring pattern for bus connecting an electric signal from a transmission element to one or more receiving element of parallel wirings having same number of bending times. SOLUTION: A multilayer wiring board is provided with a main wiring 11 and a transmission element 20 is connected with a plurality of receiving elements 30 through a plurality of wirings having equal length and meandering in parallel. Connection between the receiving element 30 and the main wiring 11 comprises the connection lead 31 of the receiving element 30, the pad 12 of the multilayer wiring board, and a connection via 13. Since a branch wiring is not required, the number of layers of the branch wiring can be decreased. When the number of bending times of the main wiring is minimized, the length of a plurality of main wirings 11 is equalized and since the number of bending times thereof is also equalized, delay time of signal propagation due to a bend is not required to be taken into account resulting in wiring where propagation delay of signal is equalized. According to the arrangement, multiplex reflection of signal waveform is reduced between the main wiring 11 and the elements 20, 30.

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 on which a large number of integrated circuits are mounted and an electric signal is distributed to the integrated circuits by a bus connection technique.

[0002]

2. Description of the Related Art In recent years, a large number of integrated circuits are mounted on a multilayer wiring board and connected to each other to form one electronic device. One of the connection methods is a bus connection. In general, when high-speed signal transmission is performed in an integrated circuit, a signal that is developed in parallel using a bus connection is transmitted using a plurality of bus lines to reduce a physical speed per line. I have.

A conventional example of this bus connection will be described with reference to FIGS. FIG. 4 is a diagram showing a wiring configuration of a conventional multilayer wiring board having bus wirings.
Denotes a receiving element, and 41 denotes a main wiring of the multilayer wiring board 40. FIG. 5 is a diagram showing a connection structure from the main wiring 41 to the receiving element 30. Reference numeral 31 denotes a connection lead of the receiving element 30, reference numeral 42 denotes a pad of the multilayer wiring board 40, and reference numerals 43 and 44.
Is a connection via of the multilayer wiring board 40, and 45 is a branch wiring of the multilayer wiring board 40. FIG. 6 shows a cross section of the structure of FIG.

As described above, in the conventional bus wiring, a plurality of parallel main wirings 41 are electrically connected to the respective elements 20 and 30 using the branch wirings 45. At this time,
Different wiring layers are provided so that the branch wiring 45 does not cross the main wiring 41, and the branch wiring 45 is laid.

FIG. 7 is a diagram showing an example of equal-length wiring using the above-described conventional wiring technique. Reference numeral 46 denotes a meandering wiring section.
In order to make the length equal to that of the main wiring 41 and the branch wiring 45, it is necessary to provide the meandering wiring section 46 in accordance with the longest wiring as shown in FIG. Further, since the number of times of bending due to the meandering wiring differs for each main wiring 41, it is necessary to design in consideration of a propagation delay generated at a bent portion. That is, it is known that the delay time in the bent portion is shorter than that in the straight wiring portion due to reflection and guidance. Therefore, it is necessary to appropriately adjust the wiring length in consideration of the delay time in the bent portion. However, the influence of reflection by the branch wiring 45 cannot be removed.

[0006]

Generally, in a device having a bus wiring, it is necessary to increase the bus width and the signal transmission speed in order to increase the processing capability. However, in the conventional structure, if the bus width is increased, the branch wiring 45 becomes longer due to a structural factor. In transmission, the effects of multiple reflections are significant. Conversely, even if the signal transmission speed is increased by suppressing the bus width, the length is limited to the longest branch wiring 45, and the signal speed cannot be maximized. Further, in the conventional structure, it is necessary to provide an extra wiring layer for the branch wiring 45. Furthermore, in order to absorb the signal propagation delay time difference due to the branch wiring length difference, the meandering wiring portion 46 has to be inserted in consideration of the delay time of the bent portion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is an object of the present invention to provide a multi-layer wiring which eliminates the effects of multiple reflections caused by branch wirings in high-speed signal transmission and the effects of timing variations among bus lines. Is to provide a board.

[0008]

According to a first aspect of the present invention to achieve the above object, one or more receiving elements are electrically connected to a transmitting element for transmitting an electric signal to the receiving elements. In a multilayer wiring board having a plurality of wiring patterns, the wiring pattern includes a plurality of main wirings, and a connecting portion that connects the main wiring and the receiving element or the transmitting element, and the main wiring is The wirings were formed of equal-length wirings which were parallel and had the same number of bendings. In a second aspect based on the first aspect, the bent wiring portion is a right-angled bent portion, a 45-degree bent portion, or a 90-degree arc-shaped bent portion.
In a third aspect based on the first aspect, the connection portion includes a pad to which a connection lead of the reception element or the transmission element is connected, and a connection via connecting the pad and the main wiring. Configured.

[0009]

1 to 3 are explanatory views of a first embodiment of the present invention. The same components as those described in FIGS. 4 to 6 are denoted by the same reference numerals. Reference numeral 10 denotes a multilayer wiring board, on which a main wiring 11 is provided. Here, between the transmitting element 20 and the plurality of receiving elements 30
The wires are connected by a plurality of main wires 11 meandering in parallel, and wires between the elements are made equal in length.

As shown in FIG. 2 and FIG. 3, the connection structure from the receiving element 30 to the main wiring 11 includes connection leads 31 of the receiving element 30, pads 12 of the multilayer wiring board 10, and connections of the multilayer wiring board 10. It is constituted by a via 13. As described above, in the present embodiment, the branch wiring is unnecessary, and the number of layers for the branch wiring can be reduced.

FIG. 8 shows a first specific example of the main wiring 11. For the four pads 12 arranged at the pitch p, 45
Four wiring parts 11 wired obliquely to form an angle of degree
A (the length in the direction of the main wiring 11 is 4p) and the length s is 4
Combining with the straight wiring part 11B where the wiring is parallel,
Connection is made between four adjacent pads 12.

At this time, the number of times of bending is four, which is the wiring that minimizes the number of times of bending. When wired in this way,
The four main wirings 11 are made equal in length, and furthermore, each main wiring 1
Since the number of bends is equal, it is not necessary to consider the signal propagation delay time due to the bent portion, and a wiring with completely equal signal propagation delay can be realized.

FIG. 9 is a diagram showing a main wiring 11 'of the second specific example. Here, with respect to the four pads 12 arranged at the pitch p, four wiring portions 11A 'having a concentric circular arc of 90 degrees (the length in the direction of the main wiring 11 is 4p) and the length s. The four wirings are combined with the parallel linear wiring portion 11B 'to connect between the four adjacent pads 12.

Also in this example, the number of bending times is four, which is the wiring that minimizes the number of bending times. With such wiring, the four main wires 11 are made equal in length. Further, the use of the arc reduces the influence of the reflection by the bent portion as compared with the case where the bending is performed at an angle. further,
Since the sum of the lengths of the arcs is the same for each wiring, it is possible to realize wirings in which signal propagation delays are completely equal without considering the signal propagation delay time difference between the arc-shaped wiring portion 11A 'and the linear wiring portion 11B'.

FIG. 10 is a diagram showing a main wiring 11 "of a third specific example. Here, four wiring portions 11A bent at 90 degrees with respect to four pads 12 arranged at a pitch p. "
(The length of the main wiring 11 in the direction of 4p) is combined with a straight wiring portion 11B "having a length s and four wirings parallel to each other.
Connection is made between four adjacent pads 12. In this example,
The operation and effect are almost the same as those of the main wiring 11 of the first specific example shown in FIG.

FIG. 11 shows a conventional main wiring 41 shown in FIG.
The wiring length between the pads 42a-42b and the pad 12a-1 of the main wiring 11 of the first specific example of the present invention shown in FIG.
The wiring length between 2b, the wiring length between the pads 12a'-12b 'of the main wiring 11' of the second specific example of the present invention shown in FIG. 9, and the third specific example of the present invention shown in FIG. A comparison of the wiring length between the pads 12a "-12b" of the main wiring 11 'of the example is shown. The pitch p is p = 0.5 mm and the length s is s = 10 mm
It is.

According to this, the conventional main wiring 41 is 29.0 mm, and the main wiring 11 of the first specific example is 27.07 m.
m, the length of the main wiring 11 'of the second specific example is 27.85 mm, and the length of the main wiring 11 "of the third specific example is 30.00 mm. The case of the main wiring 11 of the first specific example is Shortest.
Although the main wiring 11 "of the third specific example is the longest, it is superior to the conventional example because the branch wiring is not required and the length can be made equal with the same number of bendings.

[0018]

As described above, according to the present invention, in a device for connecting a signal from a transmitting element to one or more receiving elements by bus, the branch wiring from the main wiring to the receiving element can be eliminated. In addition, the influence of the multiple reflection of the signal waveform between the main wiring and the element can be minimized. Also, there is no need to provide an extra wiring layer for branch wiring,
The number of wiring layers can be reduced. Furthermore, the meandering wiring having the same number of bends can completely eliminate the timing variation of the transmission signal between the main wirings without considering the signal propagation delay time difference between the bent wiring part and the straight wiring part. Therefore,
Compared to conventional wiring, high-speed signal transmission can be performed without depending on the bus width.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of wiring in which a transmitting element and a receiving element are connected using a main wiring of a multilayer wiring board according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a connection structure between a main wiring and a receiving element according to the embodiment;

FIG. 3 is a cross-sectional view showing a connection structure between a main wiring and a receiving element according to the embodiment.

FIG. 4 is an explanatory diagram of wiring in which a transmitting element and a receiving element are connected using a main wiring and a branch wiring of a conventional multilayer wiring.

FIG. 5 is an explanatory diagram showing a connection structure between a main wiring and a receiving element of the conventional example.

FIG. 6 is a cross-sectional view showing a connection structure between a main wiring and a receiving element of the conventional example.

FIG. 7 is an explanatory diagram of wiring in which a main wiring and a branch wiring of a conventional multilayer wiring board are made equal in length.

FIG. 8 is an explanatory diagram of wiring in which the length of the wiring by the main wiring of the first specific example of the present invention is made equal.

FIG. 9 is a wiring explanatory diagram for equalizing the length of a main wiring according to a second specific example of the present invention.

FIG. 10 is a wiring explanatory diagram for equalizing the length of a main wiring according to a third specific example of the present invention.

FIG. 11 is an explanatory diagram for comparing the wiring lengths of the bus wiring of the present invention and the conventional example.

[Explanation of symbols]

10: multilayer wiring board of the present embodiment, 11, 11 ', 1
1 ″: main wiring, 12, 12a, 12b, 12a ′, 1
2b ', 12a ", 12b": pad, 13: connection via, 20: transmission element, 30: reception element, 31: connection lead, 40: conventional multilayer wiring board, 41: main wiring, 4
2: pad, 43, 44: connection via, 45: branch wiring.

Claims (3)

[Claims] 1. A multilayer wiring board comprising a plurality of wiring patterns for electrically connecting one or more receiving elements and a transmitting element for transmitting an electric signal to the receiving element, wherein the plurality of wirings are provided. The pattern includes a plurality of main wirings, and a connecting portion that connects the plurality of main wirings and the receiving element or the transmitting element, wherein the main wirings are parallel, equal-length wirings having the same number of bending times. A multilayer wiring board characterized by being formed. 2. The bent portion of the main wiring, wherein the bent portion has a right angle,
2. The multilayer wiring board according to claim 1, wherein the multilayer wiring board is a 45-degree bent portion or a 90-degree arc bent portion. 3. The device according to claim 1, wherein the connection portion includes a pad to which a connection lead of the reception element or the transmission element is connected, and a connection via connecting the pad and the main wiring. 2. The multilayer wiring board according to item 1.