EMI preventive part and active device with the same

#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.

#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.

#FIG. 1 is a perspective view showing a first embodiment of an LSI equipped with an EMI countermeasure component constituted by a composite magnetic body according to one embodiment of the present invention.

#FIG. 2 is a perspective view showing a second embodiment of an LSI equipped with an EMI countermeasure component constituted by a composite magnetic body according to one embodiment of the present invention.

#FIG. 3 is a perspective view showing a third embodiment of an LSI equipped with an EMI countermeasure component constituted by a composite magnetic body according to one embodiment of the present invention.

#Hereinbelow, an EMI countermeasure component and an active element equipped with it according to the best mode for carrying out the invention will be described with reference to the drawings.

#Referring to FIG. 1, a shown active element has an LSI 1. Also shown is an EMI countermeasure component 2 covering the LSI from its upper surface to upper portions of leads (pins) 1a at the sides of the LSI. The EMI countermeasure component 2 comprises a composite magnetic body made of soft magnetic powder having oxide films on the surfaces thereof and an organic binding agent.

#Referring to FIG. 2, a shown active element has an LSI 1. Also shown is an EMI countermeasure component 2′ covering the LSI from its upper peripheral edge portion to upper portions of leads (pins) 1a at the sides of the LSI. The EMI countermeasure component 2′ comprises a composite magnetic body made of soft magnetic powder having oxide films on the surfaces thereof and an organic binding agent.