JPH11251779A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce radiation of undesired electromagnetic wave without sacrifice of reliability by inputting a signal, obtained by inverting the input signal to a first signal wiring, to a second signal wiring and setting the amplitude of the inverted signal between specified times that of the input signal. SOLUTION: A first signal wiring (main wiring) 2 for transmitting a high speed signal, e.g. a clock signal, is formed on an insulating board 1 and a second signal wiring (sub-wiring) 3 is formed on the insulating board 1 along the main wiring 2. Furthermore, rear side of the insulating board 1 is connected with the ground potential through a ground layer. A signal, obtained by inverting the input signal to the first signal wiring 2, is inputted to the second signal wiring 3 and the amplitude of the inverted signal is set between 0.3-0.8 times that of the input signal. Radiation of undesired electromagnetic wave can thereby be reduced without sacrifice of reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device for suppressing emission of unnecessary electromagnetic waves from a wiring board or the like.

[0002]

2. Description of the Related Art With the development of multimedia, demands for high-speed data processing and data communication are increasing. In response to these demands, research and development are being actively conducted in both hardware and software, and remarkable performance improvements have been made.

In particular, in the field of semiconductor technology, the speed and function of microprocessors, which are the core of computers, and the speed and capacity of memory cells are increasing, and high-speed data processing and data communication are possible even with inexpensive personal computers. Is possible.

[0004] However, as the speed and function of LSIs increase, unnecessary electromagnetic waves radiated from electronic devices also increase with intensity and frequency, not only adversely affecting other electronic devices, but also affecting the human body. I have.

[0005] Most of the unnecessary electromagnetic wave radiation
In circuit boards on which electronic components such as SI and passive components are mounted, noise induced between signal wiring, power supply layers, and ground layers due to signal reflection, crosstalk between wirings, switching of semiconductor elements, and the like is caused. Unnecessary electromagnetic waves are radiated from the circuit board due to this noise, and further radiated outside the device through heat dissipation holes or the like of the housing.

[0006] The radiation of these unnecessary electromagnetic waves is radiated from the substrate surface on which a circuit pattern in which a high-speed signal such as a clock signal propagates is formed, and from the side surface of the substrate due to a resonance phenomenon between the power supply layer and the ground layer. Divided into radiation.

[0007] Regarding the electromagnetic wave radiation due to the resonance phenomenon between the power supply layer and the ground layer, see the proceedings of the 11th Circuit Packaging Technology Lecture Meeting of the Circuit Packaging Society of Japan, "Reduction of unnecessary radiation caused by the power supply / ground layer of the printed wiring board". As described in “Technique”, it can be suppressed by forming a ground layer on both sides of the power supply layer via an insulating layer.

On the other hand, radiation of unnecessary electromagnetic waves from the surface of a substrate on which a circuit pattern is formed is disclosed, for example, in Japanese Patent Laid-Open No.
As described in Japanese Patent Application Laid-Open No. 55-55, there is known a method in which a copper paste is applied on the surface of a circuit pattern via a solder resist, and the copper paste is connected to a ground for shielding.

Further, as described in Japanese Patent Application Laid-Open No. 9-18099, the signal wiring is disposed symmetrically with the ground wiring interposed therebetween, and is unnecessary by mutually canceling out the electromagnetic waves induced from each signal wiring. There is also known a method of preventing the generation of electromagnetic waves.

However, these methods have reliability,
There were the following problems in terms of performance. In other words, the shielding method using a copper paste described in Japanese Patent Application Laid-Open No. H8-228055 has a problem in reliability because peeling occurs due to weak adhesion between the copper paste and the solder resist.

On the other hand, the method disclosed in Japanese Patent Application Laid-Open No. Hei 9-18099, in which signal wirings are arranged symmetrically with a ground line interposed therebetween, and the electromagnetic waves induced from the respective signal wirings are mutually canceled. 10 reduction effect
% Or less, and there is a problem in performance.

[0012]

SUMMARY OF THE INVENTION As described above, Japanese Patent Application Laid-Open
The technology for suppressing unnecessary electromagnetic waves radiated from the signal wiring of the circuit board disclosed in JP-A-228055 and JP-A-9-18099 has a problem that the reliability and performance are not sufficient.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor device capable of reducing emission of unnecessary electromagnetic waves without lowering reliability. .

[0014]

Means for Solving the Problems To achieve the above object, a semiconductor device according to the present invention comprises a first signal wiring formed on a substrate and a first signal wiring formed on the substrate. A pair of second signal wirings formed along both sides of the wiring, wherein an inverted signal of an input signal input to the first signal wiring is input to the second signal wiring; When the amplitude of the signal is V1 and the amplitude of the inverted signal is V2, the relationship of 0.3V1 ≦ V2 ≦ 0.8V1 is satisfied.

According to the study of the present inventor, the first signal wiring and the second signal wiring are formed on the substrate along both sides thereof, and the first signal wiring is further formed on the second signal wiring. By inputting an inverted signal of the input signal to be input to the input signal and setting the amplitude of the inverted signal to be 0.3 times or more and 0.8 times or less the amplitude of the input signal, it can be understood that the emission of unnecessary electromagnetic waves can be sufficiently suppressed. Was.

In addition, with such a technique for suppressing the emission of unnecessary electromagnetic waves, it is basically only necessary to add a wiring for an inverted signal and a signal source, and no copper paste is required. Unlike the shielding method using a copper paste described in the gazette, there is no problem that the reliability is reduced due to the peeling of the copper paste and the solder resist. Therefore, according to the present invention, it is possible to realize a semiconductor device capable of reducing unnecessary electromagnetic wave radiation without reducing reliability.

[0017]

Embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a sectional view showing a wiring board according to a first embodiment of the present invention. The wiring board is generally multilayered like a printed wiring board, but here, for ease of explanation, a wiring board having a microstrip line structure will be described.

In FIG. 1, reference numeral 1 denotes an insulating substrate made of an insulating material such as a glass epoxy material, and a first signal wiring on which a high-speed signal such as a clock signal propagates.
(Hereinafter referred to as main wiring) 2 are formed. A pair of second signal wirings (hereinafter referred to as sub-wirings) 3 are formed on the insulating substrate 1 along both sides of the main wiring 2. The back surface of the insulating substrate 1 is connected to a ground potential via a ground layer.

Here, as a general high-speed signal transmission method, there is a method of forming a sub-wiring on one side of the main wiring through which an inverted signal of the high-speed signal propagates. In the present embodiment, a sub-wiring is provided on both sides of the main wiring 2. 3 is formed.

In this case, when a sub-wiring 3 is formed on both sides of the main wiring 2 and an inversion signal to be described later is applied to the main wiring 2, the sub-wiring 3 is formed on one side of the main wiring. Radiation noise is 1 less than when a signal is applied.
This is because it can be reduced by 0 dBμV or more.

In this embodiment, as shown in FIG. 2, the phase of the high-speed signal applied to the main wiring 2 is shifted by 180 degrees, and the voltage amplitude is 0.3 or more and 0.8 or less of the voltage amplitude V1 of the high-speed signal. Is applied to the sub-wiring 3.

In the above-described method of applying an inverted signal to one sub-wiring formed on one side of the main wiring, an inverted signal whose phase is shifted by 180 degrees from that of the high-speed signal is applied. Is the same.

In FIG. 3, the wiring width of the main wiring 2 is 125
μm, the wiring width of the sub wiring 3 is 125 μm, 250 μm,
For each of 375 μm and 500 μm, the voltage amplitude of the high-speed signal applied to the main wiring 2 is 5 V,
The measurement results when the voltage amplitude of the inverted signal applied to the sub-wiring 3 (hereinafter referred to as the inverted signal amplitude) is changed in the range of 0.0 to 6.0 V are shown.

From FIG. 3, it can be seen that the radiation noise level initially decreases with increasing inversion signal amplitude for any wiring width,
It can be seen that when the inverted signal amplitude exceeds a certain value, the inverted signal amplitude increases with the increase of the inverted signal amplitude. That is,
From FIG. 3, it can be seen that the radiation noise level has a minimum value with respect to the inverted signal amplitude.

In order to obtain a minimum value for any wiring width, an inverted signal having a voltage amplitude of 0.3 or more and 0.8 or less of the high-speed signal applied to the main wiring 2 is applied to the sub wiring 3.
It can be seen that it is sufficient to apply

Also, in the most effective case, that is, when the wiring width is 125 μm and the inverted signal amplitude is 3.5 V, the noise level can be reduced by 30 dB μV or more.

As described above, according to the present embodiment, the sub-wiring 3 is formed along both sides of the main wiring 2, and an inverted signal of the input signal input to the main wiring 2 is input to the sub-wiring 3. By setting the voltage amplitude of the inverted signal to be 0.3 times or more and 0.8 V or less of the voltage amplitude of the input signal,
The emission of unnecessary electromagnetic waves can be sufficiently suppressed.

In addition, in the case of such a technique for suppressing the emission of unnecessary electromagnetic waves, basically only the addition of the sub-wiring 3 and the inversion signal source is required, and a conventional technique requiring copper paste (Japanese Patent Laid-Open No. Hei 8-228505). Unlike the case (2), there is no problem that the reliability is lowered due to the peeling of the copper paste and the solder resist. Further, since the inverted signal amplitude may be smaller than the amplitude of the high-speed signal, an increase in power consumption can be suppressed.

Thus, according to the present embodiment, it is possible to realize a wiring board capable of reducing the radiation of unnecessary electromagnetic waves that have a great effect on the human body and electronic equipment without causing a decrease in reliability and an increase in power consumption. As a result, it is possible to contribute to environmental electromagnetic problems, which have recently become a problem worldwide. (Second Embodiment) FIG. 4 is a sectional view showing a wiring board according to a second embodiment of the present invention. Here, an example in which the present invention is applied to a general printed wiring board will be described. 1 are given the same reference numerals as in FIG. 1, and detailed description is omitted.

The main wiring 2 and the sub wiring 3 are formed on the insulating substrate 1 as in the first embodiment. The ground wiring 4 is formed on the insulating substrate 1 outside the sub wiring 3. A ground layer 5 and a power supply layer 6 are formed inside the insulating substrate 1.

In the drawing, reference numeral 7 denotes a main wiring other than the main wiring 2 (for example, a clock signal wiring), that is, a signal wiring which is not a target of suppressing unnecessary electromagnetic wave radiation.

Even when a large number of signal wirings are formed as described above, it is only necessary to form the sub-wirings 3 on both sides of the main wirings 2 through which the inverted signal propagates. If the ground wiring 4 is formed between the adjacent main wiring (signal wiring) 2, that is, if a wiring fixed to a constant voltage such as the ground potential is formed, mutual interference with the adjacent main wiring is suppressed. Thus, malfunction of the circuit can be prevented.

In this embodiment, as in the first embodiment,
By inputting the inverted signal to the sub-wiring 3 and setting the amplitude of the inverted signal to 0.3 times or more and 0.8 V or less of the voltage amplitude of the input signal, unnecessary electromagnetic waves can be sufficiently suppressed, and the reliability can be improved. There is no problem such as deterioration in performance.

As shown in FIG. 4, many printed circuit boards have a structure in which a ground layer 5 and a power supply layer 6 are formed in an insulating substrate 1, and main wirings 2 and the like are formed on the surface of the substrate. However, the present invention is effective even when the main wiring 2 and the like are formed in the insulating substrate 1.

The present invention can be applied to various substrates. In addition to the substrates described in the above embodiment, for example, a thin film substrate for a multi-chip module, a thick film multilayer wiring substrate, a build-up type printed circuit board, a ceramic multilayer wiring The present invention can also be applied to a substrate such as a semiconductor package including a substrate, a resin substrate, or a ceramic substrate. Further, it can be optimized and used depending on the type of the substrate and the type of the semiconductor to be mounted. In addition, without departing from the gist of the present invention,
Various modifications can be made.

[0036]

As described above in detail, according to the present invention, a first signal wiring and a second signal wiring are formed along both sides of the first signal wiring on a substrate, and the first signal wiring is further formed on the second signal wiring. By inputting the inverted signal of the input signal input to the wiring and setting the amplitude of the inverted signal to be 0.3 times or more and 0.8 or less of the amplitude of the input signal, unnecessary electromagnetic waves can be obtained without lowering the reliability. It is possible to realize a semiconductor device capable of reducing the emission of light.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a wiring board according to a first embodiment of the present invention;

2 shows a main wiring and a sub wiring 3 of the wiring board of FIG. 1;
Diagram showing the waveform of the voltage signal applied to

FIG. 3 is a characteristic diagram showing a relationship between radiation noise of a main wiring of the wiring board of FIG. 1 and voltage amplitude of an inverted signal applied to a sub wiring.

FIG. 4 is a sectional view showing a wiring board according to a second embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating board 2 ... Main wiring (1st signal wiring) 3 ... Sub wiring (2nd signal wiring) 4 ... Ground wiring 5 ... Ground layer 6 ... Power supply layer 7 ... Main wiring

Claims (1)

[Claims] A first signal line formed on a substrate; and a pair of second signal lines formed on the substrate along both sides of the first signal line. When an inverted signal of the input signal input to the first signal wiring is input to the second signal wiring, and the amplitude of the input signal is V1 and the amplitude of the inverted signal is V2,
A semiconductor device satisfying a relationship of 0.3V1 ≦ V2 ≦ 0.8V1.