Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
1998-08-12
2001-03-13
Sircus, Brian (Department: 2839)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
Reexamination Certificate
active
06200141
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention relates to connectors for connecting integrated circuit packages to printed circuit boards and more specifically, a connector for connecting a land grid array package to a printed circuit board.
2. Description of the Prior Art
Integrated circuits are typically housed within a package which is designed to protect the integrated circuit from damage, provide adequate heat dissipation during operation, and provide electrical connection between the integrated circuit and the leads of a printed circuit board. Several conventional packages are in the prior art including land grid array (LGA), pin grid array (PGA), ball grid array (BGA), and column grid array (CGA).
A LGA package is an integrated circuit package which has a plurality of planar metalized areas, called lands, for interconnection between the leads of the integrated circuit and a printed circuit board. LGA packages can be mounted to a printed circuit board with connectors which have been developed to maintain a solderless connection between an integrated circuit package and a printed circuit board. For example, a “fuzz ball” socket may be used to interconnect a LGA package and a printed circuit board. The “fuzz ball” socket comprises a non-conductive substrate formed with a plurality of through holes which each house a contact element. The contact elements are formed by forcing a predetermined length of gold plated wire into a through hole such that the wire will bend haphazardly into a jumbled contact that extends through the through hole and resembles a piece of steel wool. To mount a LGA package to a printed circuit board, the “fuzz ball” socket is tightly secured to a printed circuit board and, in turn, the LGA package is tightly secured to the “fuzz ball” socket. It can be appreciated, sufficient pressure must be applied to both the “fuzz ball” socket and the LGA package, respectively, to maintain electrical connections between the lands of the LGA package and the printed circuit board via the “fuzz ball” socket.
As the number of lands and corresponding “fuzz ball” contacts are increased, the pitch between contacts is correspondingly decreased and manufacturing problems increased. The placement of individual wires into evermore tightly packed through holes requires tremendous technological developments. Furthermore, “fuzz ball” sockets are relatively expensive due to costly manufacturing including the placement of individual wires into the through holes to form the various “fuzz ball” contacts.
To overcome the shortcomings of the prior art, it is an object of the subject invention to provide a connector for solderless connection between a LGA package and a printed circuit board.
It is also an object of the subject invention to provide a connector which when mounted to a printed circuit board with a LGA package secured thereto, the spacing separating the LGA package from the printed circuit board is virtually equal to the thickness of the non-conductive substrate of the connector.
SUMMARY OF THE INVENTION
To meet the above-stated objects, a connector assembly is provided for solderlessly connecting a LGA package to a printed circuit board. The connector assembly of the subject invention includes a non-conductive substrate formed with a plurality of through holes, each through hole corresponding to a land of the integrated circuit package. In one embodiment of the invention, a generally &Sgr;-shaped resilient electric contact is disposed within each of the through holes to form an electrical connection between the corresponding land and the lead of a printed circuit board. Additionally, as a second embodiment, a resilient electrical contact having a spring arm formed on one end and a ball lead formed on the opposing end is provided within each of the through holes.
With respect to the first embodiment, the generally &Sgr;-shaped resilient electrical contacts are formed with outwardly bent top and bottom arms. In an unbiased state, the bent arms extend slightly beyond the respective outer surfaces of the non-conductive substrate. During use, the LGA package and printed circuit board are respectively placed in tight face-to-face engagement with the non-conductive substrate, thereby, compressing the electric contacts into the non-conductive substrate. The compressed electrical contacts form electrical connections between the LGA package and the printed circuit board. Spring forces reactive to the compression of the electrical contacts, maintain the outer arms of the electrical contacts in tight engagement with the corresponding lands and leads. Also, due to the compression of the electrical contacts, in use, the spacing between the LGA package and the printed circuit board is virtually equal to the thickness of the non-conductive substrate. Consequently, the connector and the LGA package combination can be advantageously assembled and mounted to substantially encompass the actual sum of the dimensions of the LGA package and the connector. With space and volume within a computer being at a premium, dimensional increases added to an assembled, mounted component resulting from the mounting procedure are undesirable.
During assembly, initial contact between the LGA package and the connector, and the printed circuit board and the connector, respectively, is achieved with engagement between the respective apexes of the outwardly bent arms and the corresponding lands of the integrated circuit package or leads of the printed circuit board, respectively. With inward compression, the outwardly bent arms of each of the electric contacts pivot about the center of the respective contact with the apexes moving simultaneously in two coordinate directions, one direction being perpendicular to the substrate and the second direction being parallel to the substrate. As a result, the transverse movement of each of the apexes of the outwardly bent arms, in a direction parallel to the substrate, causes the respective bent arms to wipe the engaged land or lead. As the land or lead is wiped, hydrocarbons, dust and other contaminants are removed, and the electric connection between the contact and the corresponding land and lead is enhanced.
The generally &Sgr;-shaped electric contacts of the first embodiment of the subject invention are formed from beryllium copper segments. The segments are formed with a narrow rectangular configuration defined in a first longitudinal plane and an elongated diamond-shaped configuration defined in a second longitudinal plane, wherein the second longitudinal plane is perpendicular to the first longitudinal plane. In forming the electrical contact of the first embodiment, each of the beryllium copper segments is bent and formed from the narrow rectangular configuration to the generally &Sgr;-shape while maintaining the elongated diamond-shaped profile relative to the second longitudinal plane.
The through holes of the non-conductive substrate of the first embodiment of the socket are respectively defined by two pairs of opposing inner walls. The walls of one pair of inner walls are substantially planar, whereas the walls of the other pair of inner walls are each formed to define an outwardly pointing dihedral angle. Accordingly, each through hole cross-sectionally defines a truncated diamond profile along one coordinate axis and a generally rectangular profile along a second coordinate axis. The taper of the dihedral angles is preferably substantially equal to the taper defined by the elongated diamond profile of the respective electrical contact. With the electrical contacts being disposed in the through holes, the tapered surfaces of the electrical contacts are substantially in face-to-face engagement with the tapered surfaces of the dihedral angle, with the electrical contacts being in an unbiased state. Since the electrical contacts are each formed with an overall length which is greater than the thickness of the non-conductive substrate, the electrical contacts extend through both surfaces of the non-conductive substrate. The mating
Aries Electronics, Inc.
Casella Anthony J.
Hespos Gerald E.
Porco Michael J.
Prasad Chandrika
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