Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
1998-06-24
2001-01-16
Patel, T. C. (Department: 2839)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
C439S083000
Reexamination Certificate
active
06174172
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electric contact unit which may be used as contact probes for testing semiconductor devices, sockets for semiconductor devices and electric connectors.
BACKGROUND OF THE INVENTION
Conventionally, electric contact units having moveable contact members projecting from both sides of an insulating base board have been proposed for use as contact probe units for electrically testing electroconductive patterns of printed circuit boards and electronic component parts, sockets for semiconductor devices and electric connectors. In a typical contact probe unit employing such moveable contact members, a compression coil spring is coaxially received in each of a plurality of holders to urge a pair of contact needle members away from each other at the two opposite axial ends of the holder. The associated ends of the contact needle members and the compression coil spring are typically connected one another by soldering. Thus, an electric signal received by one of the contact needle members is transmitted to the other contact needle member via the compression coil spring.
However, when the electric signal passed through the contact probe unit is in high frequency ranges (for instance from 10 MHz to several GHz), some ill effects may be produced because the electric current is conducted by the coil-shaped electroconductive member. More specifically, when a high frequency signal is conducted through a coil-shaped electroconductive member, an inductive load is produced. Also, the resulting extended electroconductive path produces a resistive load to the detected signal.
In view of such problems of the prior art, the primary object of the present invention is to provide an electric contact unit which is low in both inductance and resistance.
BRIEF SUMMARY OF THE INVENTION
To achieve such an object, the present invention provides an electric contact unit for conducting electric current between a pair of mutually opposing parts to be contacted, comprising: a base board having a plurality of through holes passed therethrough; a plurality of coil-shaped resilient and electroconductive members passed through corresponding ones of the through holes; and insulating means for electrically insulating the coil-shaped electroconductive members from one another; each of the coil-shaped electroconductive members including an intermediate part fixedly secured in the corresponding through hole, and a pair of axially projecting parts projecting from either side of the base board.
Thus, each of the electroconductive member may consist solely of an electroconductive compression coil spring member, and the length of the electroconductive path can be minimized. As a result, the electric inductance and resistance can be minimized. When this electric contact unit is applied to a socket for a semiconductor device, the height of the socket can be minimized.
According to a preferred embodiment of the present invention, each of the parts of the coil-shaped electroconductive members includes no more than approximately one turn.
The inductance of the electroconductive member increases with the increase in the number of turns thereof. Therefore, by minimizing the number of turns of the electroconductive member while maintaining a required spring property thereof, it is possible to achieve both a desired high frequency property and a satisfactory spring property.
According to another preferred embodiment of the present invention, each of the coil-shaped electroconductive members includes no more than approximately one turn. According to this embodiment, a highly desired high frequency property can be obtained.
According to another aspect of the present invention, the intermediate part of each of the coil-shaped electroconductive members is insert molded in the insulating base board. Alternatively, each of the through holes consists of an electroconductive through hole, and the intermediate part of each of the coil-shaped electroconductive members is soldered or brazed to the corresponding through hole.
When a high contact pressure is desired, at least one of the axially projecting parts of the coil-shaped electroconductive members may comprise a wire end which extends at a certain angle away from a major surface of the base board. When the contact pressure is desired to be minimized, at least one of the axially projecting parts of the coil-shaped electroconductive members comprises a wire end which extends at a certain angle toward a major surface of the base board, or at least one of the axially projecting parts of the coil-shaped electroconductive members comprises a wire end which extends substantially in parallel with a major surface of the base board.
These and other features and advantages will become apparent from the following description with reference to the appended drawings.
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IBM Technical Disclousre Bulletin, vol. 22, No. 1, p. 158, Jun. 1979.
Allenby Chistopher B.
NHK Spring Co. Ltd.
Patel T. C.
Skjerven Morrill & MacPherson LLP
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