Electrical connectors – Electromagnetic or electrostatic shield – Multi-part shield body
Reexamination Certificate
2002-01-09
2003-02-11
Ta, Tho D. (Department: 2833)
Electrical connectors
Electromagnetic or electrostatic shield
Multi-part shield body
C439S078000, C439S943000
Reexamination Certificate
active
06517383
ABSTRACT:
BACKGROUND OF THE INVENTION
Because present trends in designing microelectronic devices and circuits are toward increased miniaturization, higher component density and greater number of component leads per piece-part, there is a corresponding need for connectors that can be configured in high-density, large-number arrays. Techniques known in the art for providing high-density interconnections between an integrated circuit (IC) or multi-chip module (MCM) and a printed wiring board (PWB) include using a quad flat-pack (QFP) which surrounds an integrated circuit (IC) or multi-chip module (MCM) on four sides with wire/lead interconnections, and using a leadless chip-carrier (LCC) which surrounds the four outer planes of an IC/MCM with vertical, flush, interconnecting leads. High-density interconnection techniques wherein connections are arranged in a two-dimensional array located under or near the substrate of an IC/MCM or the base of a PWB include the use of land grid arrays (LGA's), ball grid arrays (BGA's), and pin grid arrays (PGA's). LGA's and BGA's have become popular in part arrays (PGA's). LGA's and BGA's have become popular in part because production equipment used to mount and solder surface-mount devices onto circuit boards can be easily adapted. This ease of manufacture is enhanced by the tendency of BGAs during soldering to self-align because of the effects of surface tension caused from the molten solder.
Chip-scale packaging is another emerging technique for interfacing an IC to a substrate/circuit board. Still in its infancy, this technology has the potential to cost-effectively provide direct connections between package or circuit board input/output (I/O) pads to IC die or MCM substrates.
Because circuit miniaturization and high-density components entail ever-increasing signal speeds and input/output rates, newly developed devices increasingly require interconnections that can provide adequate shielding and maintain a proper and uniform characteristic impedance. These properties are particularly necessary to pass low-noise signals or signals with fast edges (&Dgr;v/&Dgr;t). In PWB design, characteristic impedance control has been achieved by using strip-line or micro-strip techniques which requires careful control of the size, position and spacing of circuit traces within a dielectric away from a ground or reference plane. However, applying strip-line or micro-strip connections to the inner pads of a high-density PWB becomes more difficult as circuit density increases. Also, more layers and increased manufacturing must be used when a device includes numerous, high-density, shielded and/or impedance-controlled interconnections. Increased circuit density requires more connections per unit area, especially if numerous ground planes (as required when using micro-strips or strip-lines) are utilized.
The need to interconnect to electronic components and their receptacles with impedance-controlled transmission lines is increasing with increasing clock speeds and as the density of electronic devices increase. If the impedances between the output impedance, transmission line and input impedance are not uniform, then reflections are created that decreases signal integrity and increases electromagnetic interference (EMI).
In addition, there is an increased need to integrate as many support functions in with the electronic devices to enable higher integration. Such functions include series dampening resistors and parallel loading.
DESCRIPTION OF KNOWN ART
U.S. Pat. No. 4,679,321 to J. P. Plonski describes an interconnection board for high frequency signals wherein connectors are in close proximity. The board is constructed having one side provided with a ground plane and the other side provided with terminal pads and interconnection conductors. Holes are drilled through the board at the terminal points. An end of the center conductor of a coaxial cable, stripped of insulation, is inserted through each hole while the conductive shield remains on the other side of the board. Each bare-wire conductor is connected to a pad and the conductors are scribed and bonded into place. The shields can be interconnected by applying a plated copper layer or a conductive encapsulating layer or by reflow soldering.
U.S. Pat. No. 3,114,194 to W. Lohs describes a method of wiring an electrical circuit upon an insulating plate provided with a plurality of holes, whereby wire lengths are kept as short as possible and wires can be crossed. Insulated wire is drawn through a hole in the plate and a loop formed from the wire projecting through the hole. The loop is then crushed to simultaneously anchor the loop into the hole and expose a conductive area.
U.S. Pat. No. 5,042,146 ('146) by the present inventor, discloses a process and apparatus for forming double-helix contact receptacles directly from insulated wire for interconnecting components independent of printed circuitry. Some of the apparatus disclosed therein, specifically the wire processing mechanism including cutting, stripping, and handling assemblies, is readily adaptable to the present invention which, like the '146 patent, is capable of handling and incorporating both single and twisted-pair insulated wire. Alternatively, coaxial cable can be used with the center conductor in lieu of a single conductor, provided the shield does not contact the center conductor.
U.S. Pat. No. 5,250,759 ('759), also by the present inventor, for SURFACE MOUNT COMPONENT PADS, is incorporated herein by reference in its entirety; '759 discloses a method to form pads for surface-mount electronic components by inserting a stripped portion of insulated wire into an elongated rectangular opening, and anchoring the U-shaped loop thus formed into place with epoxy or a plug. Although the pads disclosed in the '759 patents can be used with area arrays, their elongated pads will not mesh well geometrically with the square pads normally used in arrays. In addition, due to their shape, elongated pads cannot be disposed sufficiently dense in planar arrays to meet the close proximity requirements of LGA's or BGA's.
U.S. Pat. No. 5,755,596, also by the present inventor, for a HIGH-DENSITY COMPRESSION CONNECTOR, is also incorporated herein by reference in its entirety, discloses a method to form contact receptacles for high-density area arrays and connectors from sections of insulated wire. In this patent a stripped section of insulated wire is formed into a short loop, this loop inserted into an insulating sleeve, and this insulating sleeve is inserted into a receptacle of a housing.
U.S. Pat. No. 6,010,342 entitled SLEEVELESS HIGH-DENSITY COMPRESSION CONNECTOR, a continuation-in-part of '596, where the insulation portion of insulated wire takes the place of the insulating sleeve. Both the '596 and '342 patents use wire segments or loops as the central conductive elements but do not provide for the incorporation of resistive elements.
U.S. patent application Ser. No. 09/406,471 entitled “HIGH-DENSITY COMPRESSION CONNECTOR WITH RESISTIVE OPTION” filed Sep. 27, 1999 describes a pin-type compression connector that details an optional resistive element that is placed in series with the connection. The issue of characteristic impedance is discussed as a goal in this application but details on how the characteristic impedance can be varied is not discussed.
OBJECTS OF THE INVENTION
It is a primary object of the present invention to provide a mechanically rugged multiple connector assembly with capability to incorporate a controlled amount of series resistance and resistance to ground.
It is a another object of the present invention to provide a multi-unit connector assembly allowing limited control of the characteristic impedance of each signal in a high-density connector array.
Another object is to provide an ability to interconnect electronic circuit and cable assemblies by means of compression of one contact element to another.
A further object is to provide a multiple connector capabl
Leon Edwin A.
Ta Tho D.
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