Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
1998-04-22
2001-10-30
Cuchlinski, Jr., William A. (Department: 3661)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C174S034000, C174S034000, C361S773000, C361S776000, C361S813000, C428S148000, C428S143000
Reexamination Certificate
active
06310285
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an EMI (electromagnetic interference) countermeasure component and an active element equipped with it and, in particular, to an EMI countermeasure component for suppressing electromagnetic interferences, such as radiation to the exterior, performance degradation and abnormal resonance, caused by undesired electromagnetic waves at a high frequency region, and an active element equipped with it.
BACKGROUND ART
In recent years, there has been a tendency to reduce the in size of electronic devices using high frequency waves, such as digital electronic devices. And, in a digital electronic device having a high mounting density of components on a circuit board, an LSI or IC of a central processing unit (CPU), an image processor logic unit (IPLU) or the like is mounted on the circuit board. The LSI or IC is composed of a large number of semiconductor devices. Since these semiconductor devices carry out operations, such as amplification or oscillation, by receiving the supply of energy from the exterior or external source, they are generally called active elements. And, these active elements often generate inductive noise. Due to the inductive noise, high frequency magnetic fields are induced at the same surface as an element mounting surface of the circuit board and an opposite surface thereof. What is to be a problem here is a phenomenon, such as performance degradation or abnormal resonance, caused by the electrostatic coupling, an increase of the line-line coupling due to the electromagnetic coupling, or an electromagnetic interference due to radiant noise.
Conventionally, against such a so-called electromagentic interference, a measure has been taken, for example, to insert a low-pass filter into a circuit, to dispose a circuit in question at a distance or to carry out shielding, so as to suppress the electromagnetic coupling or the undesired radiant noise which causes the electromagnetic interference.
However, among the conventional measures employed to compensate for electromagnetic interference, is to insert noise filter. However, this method of carrying out the shielding is not too effective because of space requirements for mounting the noise filter. Similarly, the method of positioning the circuit in question at a distance also goes against the realization of the high density. Further, a so-called shielding method, in which a circuit subject to magnetic interference is surrounded by a metal plate or a conductive material formed by conductive plating is a technique which has been used. However, it aims to prevent leakage of the radiant noise generated in the interior to the exterior or invasion of the radiant noise from the exterior to the interior.
If the active element is too close to the semiconductive device, electromagnetic coupling is apt to occur which is undesirable. As a result, in some instances, secondary electromagnetic interference has occurred.
Therefore, an object of the present invention is to provide an EMI countermeasure component which does not adversely affects primary circuit function, but which has sufficient shielding effect against permeation of electromagnetic waves radiated to the exterior, and is further capable of suppressing a malfunction or the like due to mutual interferences between peripheral components or an electromagnetic induction to a signal line, and an active element equipped with it.
DISCLOSURE OF THE INVENTION
According to the invention as disclosed and claimed herein there is provided an EMI countermeasure component for suppressing inductive noise radiated from an active element, such as a semiconductor device, the EMI countermeasure component being characterized by a composite magnetic body essentially consisting of soft magnetic powder having oxide films on surfaces thereof, and an organic binding agent.
According to the invention as described and claimed herein there is provided an EMI countermeasure component as characterized in that the soft magnetic powder having oxide films on the surfaces thereof has a flat shape and/or a needle shape.
According to the invention as further claimed there is obtained an EMI countermeasure component as characterized in that the soft magnetic powder of the flat shape and/or the needle shape is arranged in an orientation in the composite magnetic body.
According to the invention as described and claimed an EMI countermeasure component is provided; characterized by an exposed portion formed to expose a part of a surface of the active element for heat dissipation from the active element.
According to the invention as further claimed there is obtained an active element provided with an EMI countermeasure component, said active element characterized in that one of the EMI countermeasure components is provided at an upper surface of the active element, such as a semiconductor device.
According to the invention as further described and claimed an active element is provided with an EMI countermeasure component, characterized in that one of the EMI countermeasure components is provided at sides of the active element, such as a semiconductor device.
According to the invention as described and claimed herein an active element is provided with an EMI countermeasure component, characterized in that one of the EMI countermeasure components is disposed at a bottom of an active element, such as a semiconductor device.
According to the invention as additionally claimed an active element is provided having an EMI countermeasure component characterized in that the EMI countermeasure component is disposed from the upper surface of the active element to sides thereof so as to surround upper sides of leads connected between the active element and wiring on a board on which the active element is mounted.
The invention further provides an active element having with an EMI countermeasure component characterized in that the EMI countermeasure component is disposed so as to surround leads connecting between the active element and wiring on a board on which the active element is mounted.
The invention further provides there is obtained an EMI countermeasure method characterized in that inductive noise radiated from an active element, such as a semiconductor device, is suppressed by using one of the EMI countermeasure components as described and claimed herein.
Undesired radiant noise generated from an active element, such as a semiconductor device, is largely absorbed/suppressed by means of a composite magnetic body including soft magnetic powder having oxide films on the surfaces thereof and an organic binding agent. Soft magnetic metal as being a conductive substance is ground into powder to obtain the soft magnetic powder, which is then mixed and dispersed within insulating organic binding agent so as to form an insulating film. Particularly, if the shape of the soft magnetic powder is at least one of a flat shape and a needle shape. Accordingly, the undesired radiation components can be efficiently absorbed/suppressed.
By employing a soft magnetic powder which is flat and/or has a needlelike shape, the powder exhibits magnetic anisotropy which is characterized by complex permeability due to magnetic resonance which increases in the high frequency region.
REFERENCES:
patent: 5508888 (1996-04-01), Craps
patent: 5561265 (1996-10-01), Livshits et al.
patent: 5789064 (1998-08-01), Valente et al.
patent: 0692840 (1996-01-01), None
patent: 0764954 (1997-03-01), None
Kamei Koji
Sato Mitsuharu
Yoshida Shigeyoshi
Cuchlinski Jr. William A.
Hopgood, Calimafde, Judlowe & Mondolino LLP
Mancho Ronnie
Tokin Corporation
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