JPS6254495A - Multilayer circuit wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multilayer circuit wiring board, and particularly to a multilayer circuit wiring board suitable for high-density packaging of integrated circuits that perform high-speed switching operations in high-speed computers.

(Prior Art) A conventional multilayer circuit wiring board has a plurality of signal layers laminated with ground/power layers, and the layers are insulated with a dielectric material such as ceramic and connected via through holes. In the signal layer, a signal pattern, a ground pattern, and a power supply pattern are mixed in correspondence to the allocation of terminal connections of the integrated circuit mounted on the multilayer circuit wiring board to the signal layer.

The ground pattern and the power supply pattern are generally equivalent to pads for through-hole connection between the ground layer and the Its layer, respectively, and one land portion thereof is narrow.

(Problem to be Solved by the Invention) In such a conventional multilayer circuit wiring board, an AC ground potential that affects the characteristic impedance of a signal pattern and the signal propagation speed is applied to the signal layer to which the signal pattern belongs. Depending on the stacking position, the signal pattern conductors of the ground layer, the 'I11 source layer or other signal layers become dominant. In other words, the characteristic impedance and signal propagation speed of the signal pattern in the first and second signal layers close to the ground and power layers largely depend on the distance from the ground and power layers, but in the third and higher layers, The characteristic impedance and signal propagation speed of the signal pattern in the signal layer are influenced by the signal patterns in other adjacent signal layers.

By the way, the signal pattern is determined in accordance with the terminal indirect ArR relationship of the integrated circuit, as described above.

This contact-P relationship is based on the circuit diagram of the device, so
It can be dense or sparse. If the signal pattern is dense, the conductor acts as a ground potential for the adjacent signal layer, but if it is sparse, the conductor acts as a ground potential weakly.

Therefore, the characteristic impedance and signal propagation speed of a signal layer that is three or more layers away from the ground/'At1Jlj layer are influenced by the signal pattern density of the first layer or the signal layer of the 2R signal layer, so it is important to consider this when designing the circuit. There is a problem in that it is necessary to set a large tolerance range, which impairs the realization of high-speed switching operation.

(Means for Solving the Problems) The multilayer circuit wiring board of the present invention is a multilayer circuit wiring board in which a ground layer, a power supply layer, and three or more signal layers are insulated with a dielectric material. It is configured by wiring the ground pattern along a predetermined portion of the signal pattern on at least one side of at least one of the signal layers separated by three or more layers from the ground/power layer.

(Example) Next, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view including an embodiment of the present invention, and FIG. 2 is a plan view of layer No. 736 shown in FIG. 71. The multilayer circuit wiring board shown in FIG. Substrate 1 with
On top, a ground layer 3, a first signal layer 4, a second signal layer 5, and a 43 signal j6 are laminated with a dielectric 2 interposed therebetween. Equipped with LSI8. Through holes for connecting between each layer and between the input/output pin 7 and each layer are omitted from illustration.

@[Since the signal layer 4 and the second signal layer 5 are relatively close to the ground/power layer 3, their characteristic impedance and signal propagation speed are be influenced by. However, since the third image layer 6 is located relatively far from the ground/'It source layer and the image layer, the second
The density of signal patterns in the signal layer 5 and the first signal layer 4 is influenced in various ways by the second signal layer 5, the first signal layer 4, and the ground pattern 3.

In other words, if the signal pattern of the second signal Ja5 is dense, the third signal layer 6 is used for the second signal layer 5, and even if the signal pattern of the second signal layer 5 is sparse and the signal pattern of the first signal layer 4 is dense. Ba8f! 1 signal layer 4, second signal layer 5 and first signal layer 4
If each signal pattern is sparse, the ground/power supply layer 3 tends to act as an alternating current ground potential. It goes without saying that these L actors act to an appropriate degree depending on the degree of sparseness and density of the signal pattern.However, in order to simplify the explanation, the above-mentioned mechanism will be expressed simply. Did.

Next, referring to Fig. 72, signal pattern 11°12?
Ground pattern 2 is placed in parallel to each adjacent to the workpiece 13.
1+22S" process 23 is provided. These ground patterns 21, 22 and 23 are connected to the ground part of the ground layer 3 via through holes to maintain the ground potential. Signal pattern 11.
12 and 13 are the tL ground patterns 21 and 13, respectively.
22 and 23, the second signal layer 5 and the first
Various influences from the image layer 3 can be eliminated from the signal R14 and the ground.

In FIG. 2, three signal lines 11.
12>Method 13 is shown in Figure 9, but for a signal pattern where you want to reduce the fluctuation width of the characteristic impedance and signal propagation speed, you can do it by making the ground pattern run along it in the same way.

Although only one side of the third signal layer 6 is shown in FIG. 2, it is possible to provide a dominant ground potential to the signal pattern on the other side even if many ground patterns are provided along only one side. become. However, it goes without saying that the effect will be enhanced if the ground pattern is aligned with the signal pattern on both sides.

Furthermore, although the multilayer circuit wiring board shown in FIG. 1 is a three-layer circuit wiring board, in the case of a multilayer circuit wiring board with four, five, or more layers, the i1 !2
By applying the measures shown in the figure, the same effect can be obtained.

(Effects of the Invention) The multilayer circuit wiring board of the present invention has the advantage of providing a ground pattern close to a signal pattern in a signal layer that is three or more layers away from the ground/power layer, and can eliminate the influence of other signal layers. Therefore, there is an effect that the fluctuation width of the characteristic impedance and signal propagation speed of the signal layer can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view including one embodiment of the present invention, and FIG.
FIG. 3 is a plan view of the third signal layer shown in the figure. 1...Substrate, 2...Dielectric, 3...
...Ground/power layer, 4...First signal layer,
5... Second signal layer, 6... Third signal layer, 7... Input/output bin, 8... LSI,
11, 12.13...Signal pattern, 21.2
2, 23... Ground pattern. Agent Patent Attorney Susumu Uchihara ”' ”,”,,
1st cow

Claims (1)

[Scope of Claims] In a multilayer circuit wiring board in which a ground/power layer and three or more signal layers are insulated with a dielectric, one of the signal layers separated from the ground/power layer by three or more layers. A multilayer circuit wiring board characterized in that at least one of the above includes a ground pattern wired along a predetermined signal pattern on at least one side.