A plethora of applications exist for effecting electrical contact between two conductors. Examples of such applications include cable connectors, PC board connectors, socket connectors, DIP carriers, etc. In an illustrative application, an interconnect system may effect an interconnection between a number of terminals on a first printed circuit board with a number of corresponding terminals on a second printed circuit board. Such apparatus are used to provide an electrical interface between two circuit boards. In another illustrative application, an interconnect system may effect an interconnection between a lead of an integrated circuit device and a conductive pad or terminal on a printed circuit board. The circuit board may then be coupled to a tester apparatus or other control means. Such apparatus are used to evaluate the performance of integrated circuit devices.
Numerous considerations bear upon the structure of an electrical interconnect system, including both electrical and mechanical considerations. For typical interconnection systems, special attention must be given to the electrical performance thereof including self inductance, resistance, capacitance, impedance matching characteristics, etc. Mechanical considerations including life span requirements, repairability or replacability, operating temperature requirements, etc., must also be considered. Finally, specific applications of an electrical interconnect system may yield a number of unique parameters which must also be considered. For example, in an interconnect system which provides an electrical interconnection between an integrated circuit lead and a printed circuit board terminal, various parameter must be considered including the coplanarity of the terminals, the mechanical manufacturing tolerances, and the device alignment and orientation of the device terminals relative to the interconnection system.
A main objective of an interconnection system is to maintain a non-distorting electrical interconnection between two terminals. To accomplish this, an interconnection system must be carefully designed to control the lead inductance and resistance, the lead-to-lead capacitance, the lead-to-ground capacitance, the electrical decoupling system, and the impedance matching characteristic of signal paths. All of these characteristics contribute, to some degree, to the distorting nature of the electrical interconnection system.
Various methods have been developed to help minimize the parasitic effects of the interrconnect system. A common method is to provide signal condition circuits adjacent the electro-mechanical contacts of the electrical interconnection system. The signal conditioning circuits, typically discrete elements such as termination components are used to adjust and control the circuit impedance. Because the requisite signal conditioning components and electromechanical contacts are physically separated, it is difficult to attain an ideal interconnect system, thereby compromising the accuracy, precision and reproducibility of the interconnect system.
One prior art structure is suggested in U.S. Pat. No. 4,260,762, issued on Apr. 29, 1975 to Lockhart, Jr. Lockhart suggests a test socket for interconnecting a dual-in-line integrated circuit package and a printed circuit board. A capacitor is provided in the body of the socket wherein the socket material provides the dielectric for the capacitor. The contacts of the capacitor are in contact with the socket connectors, which are in turn in contact with the integrated circuit package. That is, Lockhart suggests a test socket wherein the capacitor is provided in the socket body, rather than on the "load board" as previously discussed.
A scheme to connect a first circuit board containing a test socket to a coaxial probe card, and eventually to an IC tester is suggested in U.S. Pat. No. 4,996,487, issued on Feb. 26, 1991 to Pope. The first circuit board has an integrated circuit test socket connected thereto and traces from the integrated circuit test socket to plated through-holes and further to blind vias. The coaxial probe card then engages the blind vias to provide an electrical communication path between the IC tester and the integrated circuit test socket.
A method for reducing noise in a telephone jack is suggested in U.S. Pat. No. 4,695,115, issued on Sep. 22, 1987 to Talend. Talend suggests a modular jack for telephones in which discrete bypass capacitors are connected to the leads of the jack to filter out noise thereon. Talend contemplates using monolithic surface mount capacitors which extend to a ground plane in the modular jack element.
The use of a pi-network to reduce noise in a connector is suggested in U.S. Pat. No. 4,853,659, issued on Aug. 1, 1989 to Kling. Kling suggests using a planer pi-network filter comprising a pair of shunt capacitors and an inductive member in series therebetween. Kling contemplates using the pi-network filter in combination with cable connectors or the like.
A millimeter-wave probe for use in injecting signals with frequencies above 50 GHz is suggests in U.S. Pat. No. 4,983,910, issued on Jan. 8, 1991 to Majidi-Ahy et al. In Majidi-Ahy et al. an input impedance matching section couples the energy from a low pass filter to a pair of matched, anti-parallel, beam lead diodes. These diodes generate odd numbered harmonics which are passed through the diodes by an output impedance matching network.
Finally, a capacitively loaded probe which can be used for non-contact acquisition of both analog and digital signals is suggested in U.S. Pat. No. 5,274,336, issued on Dec. 28, 1993 to Crook et al. In Crook et al., the probe consists of a shielded probe tip, a probe body which is mechanically coupled to the probe tip, and an amplifier circuit disposed within the probe body.