Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – For plural devices
Reexamination Certificate
2001-07-25
2004-10-12
Thomas, Tom (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
For plural devices
C257S787000, C257S723000, C257S924000, C257S516000, C257S532000, C361S729000, C361S730000, C174S050000, C174S051000
Reexamination Certificate
active
06803655
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device, an electric circuit device, electronic equipment, and control equipment in which countermeasures against EMI (electromagnetic interference) are taken. More specifically, the present invention relates to a semiconductor integrated circuit device, an electric circuit device, electronic equipment, and control equipment for preventing EMI caused by switching noise generated in the power circuit of a die.
2. Background
Simultaneous with the increase in the internal operating frequency and power consumption of semiconductor integrated circuit devices, EMI caused by the switching noise of the internal power circuit in semiconductor integrated circuit devices has raised serious problems. The switching noise current of the internal power circuit in semiconductor integrated circuit generates a loop current in an IC package, and a loop current circulating through the IC package and the PCB (printed circuit board) outside the IC package. These loop currents generate electromagnetic fields that radiate from the IC package and the PCB causing EMI in the surrounding environment.
One of the conventional countermeasures against the EMI of semiconductor integrated circuit devices is to place a decoupling capacitor between the power line and the ground line of the PCB. Although this conventional countermeasure can inhibit the radiation of electromagnetic fields from the PCB, it is difficult to inhibit the radiation of electromagnetic fields from the semiconductor integrated circuit device itself. Also, in order to prevent EMI caused by the entire PCB on which a large number of semiconductor integrated circuit devices are mounted, decoupling capacitors must be provided on the PCB to correspond to each power lead of each semiconductor integrated circuit device. As the number of decoupling capacitors on the entire PCB increases, problems arise such as increasing the size of the PCB, increasing the number of components on the PBC, and difficulty in finding locations to install decoupling capacitors on the PCB. Also, there is a case where an island-shaped ground plane is formed on the surface of a PCB that is covered with semiconductor integrated circuit devices in order to shield the electromagnetic fields radiated from the semiconductor integrated circuit devices. It is difficult, in this case, to form various wirings on the ground plane.
Japanese Published Unexamined Patent Application No. 4-277665 discloses a socket used for the tester of semiconductor integrated circuit devices. This socket comprises a contact fixed on the testing board for contacting and pressing the leads of semiconductor integrated circuit devices, an electrical conductor disposed so as to contact the ground pattern on the surface of the testing board, and a decoupling capacitor intervening between the contact and the electrical conductor. However, this structure is applied to the socket of a semiconductor integrated circuit device, and does not act to inhibit the switching noise current that is output from the semiconductor integrated circuit device. Also in this socket, since the electrical conductor contacts the ground pattern on the surface of the testing board two-dimensionally, and the impedance between the decoupling capacitor and the testing board is substantially lower than the impedance between the decoupling capacitor and the semiconductor integrated circuit device, the socket cannot inhibit the flow of the switching noise current leaked from the semiconductor integrated circuit device to the testing board.
In the semiconductor integrated circuit device disclosed in Japanese Published Unexamined Patent Application No. 8-17960, the bottom of the semiconductor integrated circuit device is formed of a ground plane, or from a central mounting plate and a circumferential power supply frame, and the ground plate and the power supply frame substitute for ground leads and power leads, thereby decreasing the number of leads on the side of the semiconductor integrated circuit device. Furthermore, in FIG. 4(
b
) of Japanese Published Unexamined Patent Application No. 8-17960, a power supply plane facing the ground plane is provided in the package of the semiconductor integrated circuit device, so that the power supply plane and the ground plane constitute a decoupling capacitor. In this semiconductor integrated circuit device, however, the ground plate and the power supply frame are directly and two-dimensionally in contact with the ground line and the power line of the PCB, and as a result, the impedance between the ground plane and the power supply frame, and the PCB is substantially lower than the impedance between the ground plane and the power supply frame, and the die. Further, the leakage of the noise current to the PCB cannot be sufficiently inhibited. In this semiconductor integrated circuit device, since the ground plane is used both as the path of the switching noise current returned from the die through the decoupling capacitor to the die in the package, and as the path of the return current of the transmission signal, ground-bound noise generated by the inductance of the ground plane cannot be inhibited. Furthermore, in this semiconductor integrated circuit device, since the center of the ground plane is protruded and the die is disposed on the protruded surface, problems such as an increase in capacitance of the internal circuit of the IC package, and degradation of the quality of the signal transmission in the die may occur.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a semiconductor integrated circuit device that can effectively inhibit EMI caused by a loop current circulating between the package and the printed circuit board for mounting electronic parts caused by the switching noise current of the internal power supply circuit in the semiconductor integrated circuit device.
Another object of the present invention is to provide a semiconductor integrated circuit device that can effectively inhibit EMI caused by a loop current in the package caused by the switching noise current of the internal power supply circuit in the semiconductor integrated circuit device.
Another object of the present invention is to provide a semiconductor integrated circuit device that does not require forming an island-shaped ground plane on the printed circuit board for mounting electronic parts for shielding the printed circuit board from the electromagnetic fields radiated by the semiconductor integrated circuit device.
Another object of the present invention is to provide an electric circuit device that can effectively inhibit EMI caused by semiconductor integrated circuit devices, and the printed circuit board for mounting electronic parts.
Another object of the present invention is to provide electronic equipment and control equipment furnished with semiconductor integrated circuit devices, and can effectively inhibit EMI.
A semiconductor integrated circuit device according to a first aspect of the present invention comprises:
a die connected to a ground lead and a power lead,
a ground plane extending two-dimensionally and connected to the ground lead,
a decoupling capacitor connected to the ground lead at one end and to the power lead at another end, and
an encapsulating material for encapsulating the die, ground plane, and decoupling capacitor.
When the surfaces of a semiconductor integrated circuit device facing the printed circuit board for mounting electronic parts and facing opposite to the printed circuit board for mounting electronic parts are defined as the bottom surface and the top surface, respectively, the ground plane is typically parallel to the top and bottom surfaces of the encapsulating material, but is not necessarily parallel The ground plane is preferably perpendicular to the direction in which the inhibition of electromagnetic radiation from the semiconductor integrated circuit device is desired. The ground plane is not limited to be flat, bu
Fujio Shohhei
Kabayama Hideki
Canale Anthony J.
Chu Chris C.
Thomas Tom
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