Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
1999-09-01
2001-08-28
Ta, Tho D. (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
C439S074000, C439S091000, C439S591000, C439S573000, C411S389000, C174S13800J, C361S804000
Reexamination Certificate
active
06280202
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to devices for alignment and connection of planar electronic components such as printed circuit boards. More particularly, the present invention relates to an improved board-to-board securement device for successful alignment and connection of adjacent, planar components in spaced parallel relation in an electronic device or system so as to prevent overcompression of elastomeric contact elements positioned therebetween.
BACKGROUND OF THE INVENTION
Electronic devices and systems are integral facets of every industry and profession. The evolution of electronics allows for the integration of more electronic circuits in a wide variety of equipment. Concurrently with the rapid growth of certain electronic hardware such as cellular and other portable communications devices, laptop and notebook computers, home and office Internet access equipment, there has been a demand on reducing the various IC packaging schemes. Connector manufacturers have had to scale down connectors to fit these miniaturized products. Reliable miniaturization, therefore, is a significant factor in connector design.
One of the challenges for system designers has been to provide an interconnection path for densely integrated silicon devices onto a motherboard. One of the barriers to integrating even more functions into a single chip has been the input/output (“I/O”) limitations of conventional interconnect technology.
A modern solution developed to overcome the problems inherent in establishing and maintaining aligned connections between electronic components is the use of metallized particle interconnect (“MPI”) contacts. MPI contacts are elastomeric contacts which integrate semi-conductive material therein. The MPI contacts are designed to provide an electrically and mechanically reliable, low-cost interconnection method for high-density printed circuit board (“PCB”) components without the use of metal pins or solder techniques. The conductive path has similar electrical properties to a metal pin or solder contact.
The MPI material, an elastomeric material with semiconductive particles dispersed therein, is formed into tiny micro columns and held in a grid pattern by a thin polyamide substrate which aligns with the lands of a packaged silicon device and the landing pad of the PCB. When mechanically compressed, the micro columns align with the pads on an LGA package and the landing pads of a PCB, forming a conductive path therebetween. The flexible polymer/metallization columns act as shock absorbers allowing for excellent performance under extreme shock/vibration testing. Also, the elasticity of the polymeric column acts as a seal to the environment at the point of connection, protecting the connection from harmful elements.
MPI technology is seen as a solution to integrating high-density microprocessors and other silicon devices onto the motherboard, both in terms of I/O count as well as the potential for far lower costs than other interconnections. The MPI technology has the potential to double or even triple the upper limit for I/O. With a higher density interconnection technology such as this, designers will be able to integrate the functions of several chips into a single piece of silicon, thereby reducing the number of components, interconnections and overall size of the PCBs. At a low cost per contact with an integral heat sink, and exceptionally low tooling costs, MPI has great potential to replace most of the interconnects in PCS, laptops and other electronic devices.
MPI contacts are not only desirable because of their superior mechanical, electrical and thermal performance, but also because of the cost per contact is significantly lower than mechanically complex cartridge-type interconnects or conventional board-to-board, metal pin-and-socket or BGA devices. The MPI material's polymer/metallization combination also provides superior resistance to environmental and shock/vibration conditions as well as excellent conductive performance, both electrically and thermally.
The problem remains, however, of alignment and connection of planar components such as PCBs to one another to maintain interconnection therebetween. As pin counts continue to increase with the advent of MPI and related technologies, it becomes increasingly important to achieve and maintain alignment of adjacent elements in an electronic device or system to prevent vibrations therein which may negatively affect the proper operation of such elements and the system as a whole.
Devices for securement of planar elements such as those utilized in electronic components are well-known and widely employed. In conventional connectors, a locating pin is mounted on a connector that protrudes above and below the connector. The locating pin aligns the connector to a pair of planar elements such as a motherboard and daughtercard by holes located in the boards just for this purpose. Examples of such connectors include U.S. Pat. No. 4,309,856 to Varnau et al. which discloses a resilient device for securing panels in parallel spaced relation to a support bracket; U.S. Pat. No. 4,760,495 to Till, which provides a “stand-off device” to control the spacing between adjacent planar elements in electronic instrumentation; and U.S. Pat. No. 4,875,140 to Delpech which discloses a support device for printed circuit boards formed by a column having at least one base on which a circuit board is to be supported with the boards and a coupling member fixed by a screw.
One problem inherent in traditional electronic connectors such as these is that such elements require additional fastening hardware to join the assembly of connector and boards together. Additional holes must therefore be provided in the PCB, decreasing the are available for routing circuitry and consequently increasing the difficulty of board design. Moreover, the above devices permit excessive compression of contacts, between the planar elements, negating proper performance of the contacts and obviating the beneficial results of the alignment operation. This is of particular concern with electronic contacts. Thus, additional hardware is required to prevent overcompression of the contacts. Such obstacles to circuitry routing contribute significantly to higher board costs.
Accordingly, it is an object of the present invention to provide a unitary securement member that provides alignment of adjacent planar components in a spaced parallel relation and furthermore prevents overcompression of contacts therebetween.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved alignment and securement device for planar elements in a system of electronic components.
It is another object of the present invention to provide a securement device for adjacent planar elements which ensures alignment of the elements in spaced parallel relation.
It is yet another object of the present invention to provide a securement device which achieves alignment of planar elements while preventing overcompression of electrical contacts therebetween.
It is a further object of the present invention to reduce the number of apertures for fastening hardware through planar components, thereby increasing the area available to route circuitry thereon.
In the efficient attainment of these and other objects, the present invention provides a securement device to align adjacent printed circuit boards, such as a motherboard and daughtercard (collectively “PCBs”), while simultaneously connecting all external hardware so as to prevent overcompression of elastomeric contacts positioned therebetween during assembly. The device supports a connector between a pair of PCBs in spaced parallel relation, wherein the connector itself supports a plurality of elastomeric contacts thereon for establishing electrical engagement between the PCBs. The PCBs and the connector each include aligned securement openings.
The device includes an elongate fastener having a substantially cylindrical section positioned in the connector opening. The cylindrical section defines
Alden, 3rd Wayne S.
Petrocelli William
Hoffman & Baron LLP
Ta Tho D.
Thomas & Betts International Inc.
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