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US 8,427,186 B2Granted
Probe element having a substantially zero stiffness and applications thereof
AssigneeFormFactor, Inc.
InventorAndrew W. McFarland
Life of this patent
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Abstract
A microelectronic probe element can include a base, a tip, and a spring assembly coupled between the tip and the base. The spring assembly can include a first spring and a second spring, wherein the first spring has a negative stiffness over a predefined displacement range and the second spring has a positive stiffness over the predefined displacement range. The first spring and second spring can be coupled so that the negative stiffness and positive stiffness substantially cancel to produce a net stiffness of the tip relative to the base over the predefined displacement range.
Claims23
A microelectronic probe element for making pressure-based electrical contact to a microelectronic device for testing said microelectronic device, said microelectronic probe element comprising:
- a base;
- a tip electrically connected to said base and comprising a conductive material suitable for making pressure based electrical contact to a microelectronic device;
- a spring assembly coupled between said tip and said base, said spring assembly comprising:
- a first spring, wherein said first spring has a first spring characteristic comprising a negative stiffness over a predefined displacement range of said tip relative to said base;
- and
- a second spring, wherein said second spring has a second spring characteristic comprising a positive stiffness over said predefined displacement range, wherein said first spring and said second spring are coupled so that said positive stiffness substantially cancels said negative stiffness to produce a net spring characteristic of said tip relative to said base over said predefined displacement range.
3 more elements
A probe card assembly comprising:
- a rigid substrate;
- an electrical interface coupled to said substrate;
- a plurality of probes coupled to said substrate and arranged to contact terminals of a microelectronic device, wherein said substrate comprises electrical connections between said probes and said electrical interface, wherein ones of said probes comprise a first spring element and a second spring element coupled together;
- and
- wherein said first spring element and second spring element comprise spring characteristics that are complementary to each other over a predefined displacement range so that over said predefined displacement range said ones of said probes provide a contact force having a substantially constant magnitude,
- wherein said ones of said probes provides a substantially zero stiffness over said predefined displacement range, and wherein over an initial displacement range less than said predefined displacement range said ones of said probes provide a positive stiffness.
3 more elements
A probe card assembly comprising:
- a rigid substrate;
- an electrical interface coupled to said substrate;
- a plurality of probes coupled to said substrate and arranged to contact terminals of a microelectronic device, wherein said substrate comprises electrical connections between said probes and said electrical interface, wherein ones of said probes comprise a first spring element and a second spring element coupled together;
- and
- wherein said first spring element and second spring element comprise spring characteristics that are complementary to each other over a predefined displacement range so that over said predefined displacement range said ones of said probes provide a contact force having a substantially constant magnitude,
- wherein:
- said first spring element comprises a bi-stable spring;
- and
- said second spring element comprises a linear spring connected to said first spring in a parallel arrangement.
6 more elements
A process of using a probe card assembly comprising:
- obtaining a probe card assembly comprising a plurality of probes coupled to a substrate and each comprising a tip, said plurality of probes arranged so said tips can contact corresponding terminals of a microelectronic device, and each of said probes comprising a first spring element and a second spring element;
- positioning said probe card assembly and said microelectronic device together to make contact between said probes and said terminals;
- displacing said probe card assembly and said microelectronic device together by an initial over travel displacement, wherein ones of said plurality of probes deflects and develops an initial contact force in reaction to said initial over travel displacement, said initial contact force being substantially linearly proportional to said initial over travel displacement, and said initial contact force obtained by a combination of positive stiffness of said first spring element and positive stiffness of said second spring element over said initial over travel displacement;
- and
- increasing displacement of said probe card assembly relative to said microelectronic device by an additional over travel displacement, wherein said ones of said plurality of probes further deflects and provides a sustained contact force substantially equal to said initial contact force substantially independent of said additional over travel displacement, said sustained contact force being maintained by a combination of positive stiffness of said first spring element and negative stiffness of said second spring element over said additional over travel displacement.
2 more elements
Dependencies are inferred from the claim text.