Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
1999-04-07
2001-04-17
Luebke, Renee (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
Reexamination Certificate
active
06217342
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to interposer assemblies used for forming electrical connections between spaced contact pads on circuit members.
DESCRIPTION OF THE PRIOR ART
Interposer assemblies are used for forming electrical connections between densely spaced contact pads on adjacent parallel circuit members. The pads on the members are arranged in identical patterns. Commonly, the circuit members are a circuit board and a ceramic plate carrying integrated circuits. The interposer assembly includes an insulating plate and a plurality of through-contacts carried in the plate and arranged in the same pattern as the pads on the circuit members. The contacts project above the top and bottom sides of the plate. The interposer assembly is sandwiched between the two members which are held together with the contacts forming electric connections between aligned pairs of pads.
Interposer assemblies form electrical connections between contact pads arranged in a very close proximity to each other. The pads may be arranged on a one millimeter center-to-center grid. Each assembly may have as many as 961 contacts. Four assemblies are conventionally mounted on a single frame with a total of 3,844 contacts in the frame. In addition to requiring contacts which can be spaced very close to each other, the contacts must make reliable electrical connections with the pads when the assemblies are sandwiched between the circuit members. Failure of a single contact to make a reliable connection renders the entire frame useless.
A low mechanical closure force is required in order to prevent undue stress on a ceramic circuit member. A high closure force could distort or possibly break the ceramic member. Further, interposer assemblies must occupy a minimum width between the circuit members, requiring that the individual electrical contacts in the assembly have a limited height yet possess the required spring properties for establishing reliable electrical connections between the pads without undue closing force.
Conventional interposer assemblies use contacts which occupy a relatively large amount of space in the supporting plate making it difficult to meet closely spaced grid requirements. These assemblies are relatively expensive to manufacture and assemble.
SUMMARY OF THE INVENTION
The invention is an improved interposer assembly including metal through contacts loosely confined in closely spaced passages extending through an insulating plate. The contacts include arcuate portions which when compressed are elastically bent to form wiped pressure connections with opposed pads and reduce the force necessary to sandwich the interposer assembly between the circuit members. The low closure force reduces the risk of damage to an overlying ceramic substrate and allows a large number of contacts in the assembly. The wiped electrical connections between the contacts and the circuit pads form reliable electrical connections between the adjacent pairs of pads and permit installation of the interposer assemblies in user's facilities. The assemblies need not be installed in clean rooms.
The disclosed interposer assemblies use plates and contacts which are easily and inexpensively manufactured and assembled. The plate is a one-piece design and includes through passages with contact retention projections extending into the passages. The arcuate contacts are readily inserted into the passages to snap or latch over the projections, which then hold the contacts loosely in place in the passages prior to sandwiching of the assemblies between circuit members. The contacts are compact, permitting use of the assembly to form electrical connections between very closely spaced contact pads.
In a first embodiment each contact retention projection includes a sloped cam surface facing one side of the plate. The through contacts are inserted into the plate from the side adjacent the cam surfaces. During insertion, cam followers on the lead ends of the contacts engage the cam surfaces and are guided over the retention projections. When fully inserted, the contacts are held in the passages by the retention projections which extend between the free ends of the contacts. The contacts are loosely held in the passages with opposed contact noses spaced apart a distance greater than the thickness of the plate. When compressed, the contacts establish reliable wiped contacts with opposed pads.
In a second embodiment sloped cam surfaces are provided on both sides of the projection. The arcuate through contacts may be inserted from either side of the plate. During insertion, cam followers on the lead ends of the contacts engage cam surfaces and are guided past the projections which then hold the contacts in place. The contact noses are spaced apart a distance greater than the thickness of the plate to form wiped pressure contacts with opposing pads.
When a contact is positioned in a through passage in the second embodiment, rounded surfaces at the free ends of the contact are located adjacent the cam surfaces on opposite sides of the projection. The cam surfaces hold the contact loosely within the passage for floating engagement with opposed contact pads and formation of reliable wiped pressure connections with the pads. The free ends of the contacts are held within the thickness of the plate to limit contact float. The sloped cam surfaces extend to the adjacent walls of the contact passages and assure that during insertion of the contacts into the passages the lead ends of the contacts are guided smoothly over the projections and do not hang up in the corners or junctions between the projections and the adjacent walls. On rare occasions, contacts inserted into the passages in the first embodiment interposer assembly catch in the corners and have been permanently shortened, destroying their ability to form connections between pads.
Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings illustrating the invention, of which there are six sheets of drawings and two embodiments are disclosed.
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Neidich Douglas A.
Walden John D.
Hammond Briggitte
InterCon Systems, Inc.
Luebke Renee
Thomas Hooker, P.C.
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