Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
1999-03-02
2001-06-12
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C428S687000, C324S754090, C324S757020, C200S279000, C205S111000
Reexamination Certificate
active
06245445
ABSTRACT:
BACKGROUND
This invention relates to rough electrical contact surfaces. For example, rough surfaces may be useful on contact pad surfaces in thin-film membranes used for testing integrated semiconductor devices. The contact pad surfaces make contact with device pads on the surface of semiconductor devices. See co-pending U.S. patent application Ser. No. 08/303,498. Because device pads can develop oxide layers, the membrane contact pads must penetrate oxide layers or other contaminants to make good electrical connections.
One method of penetration wears away the oxide layer by force often combined with rubbing motion. Another method of penetration uses contact pads having roughened surfaces that can pierce through the oxide layer. The roughened surface can be made, for example, by depositing already-formed, small, hard (e.g., of rhodium or titanium carbide) particles on the surface of a contact pad, and then electroplating the whole assembly with a thin layer of nickel.
SUMMARY
In general, in one aspect, the invention features a method for rendering a surface of a contact rough, including submerging the surface of the contact in an electroplating bath having a dissolved metal salt, and pulsing an electric current through the contact and the bath to form a rough metallic structure on the surface of the contact.
Implementations of the invention may feature the following features. The dissolved metal salt may include nickel chloride. The electroplating bath may have a concentration of about 150 to about 400 grams of nickel chloride dissolved in a liter of water. The electroplating bath may be heated to about 55 degrees C.±about 5 degrees. The electric current may have a current density of between about 35 amps per square foot to about 75 amps per square foot. The rough metallic structure may be plated with gold. The electric current may be pulsed for a length of time between 0 and about 3 minutes, and may be pulsed with a duty cycle having an on period greater than an off period. The ratio of the on period to the off period may be between about 4:1 and about 8:1. The on period may be between about 0.4 seconds and about 0.8 seconds, and the off period may be about 0.1 seconds. The ratio of the on period to the off period may be about 6:1, and the on period may be about 0.6 seconds and the off period may be about 0.1 seconds.
The rough metal structure may be comprised of spikes. The spikes may be substantially conical. The spikes may have a height between about 0.350 microns and about 1.275 microns. The spikes may have a base between about 0.345 microns and about 1.250 microns. A side of each of the spikes may have an angle from normal of between about 10 degrees and about 45 degrees. The spikes may have a density of between about 1 and about 2 spikes per square micrometer.
In general, in another aspect, the invention provides a roughened contact including a contact having a surface, and a solid metal layer deposited on the surface of the contact and having spikes protruding away from the contact.
In general, in another aspect, the invention provides a roughened contact including a contact having a surface, a solid metal layer deposited on the surface of the contact, wherein the solid metal layer comprises nickel, having spikes protruding away from the contact, wherein the spikes are substantially conical, the spikes have a height between about 0.350 microns and about 1.275 microns, the spikes have a base between about 0.345 microns and about 1.250 microns, wherein a side of each of the spikes has an angle from normal of between about 10 degrees and about 45 degrees, and wherein the spikes have a density of between about 1 and about 2 spikes per square micrometer, and a conductive plating deposited on the surface of the solid metal surface, wherein the conductive plating comprises gold.
In general, in another aspect, the invention provides a membrane for use in testing a circuit including a flexible membrane substrate, a contact on the flexible membrane substrate having a surface, and a solid metal layer deposited on the surface of the contact and having spikes protruding away from the contact.
Implementations of the invention may feature the following features. The spikes may be substantially conical. The solid metal layer may include nickel. A conductive plating may be deposited on the surface of the solid metal layer. The conductive plating may include gold. The flexible membrane substrate may include a polyimide film.
The advantages of the invention may include one or more of the following. Relatively sharp spikes may be created on the surface of a contact. These spikes may be deposited with a relatively uniform height, and dispersed relatively evenly across the contact surface. These spikes do not require the dropping of hardened particles onto the contact surface. Instead, these spikes may be created through a simple, continuous electroplating process. The hard, sharp spikes reduce damage to small and delicate components and form consistently reliable connections.
Other features and advantages of the invention will become apparent from the following description and from the claims.
REFERENCES:
patent: 4038158 (1977-07-01), Bursey et al.
patent: 4436591 (1984-03-01), De Hek
patent: 4461680 (1984-07-01), Lashmore
patent: 4804132 (1989-02-01), DiFrancesco
patent: 5083697 (1992-01-01), DeFrancesco
patent: 5185073 (1993-02-01), Bindra et al.
patent: 5213876 (1993-05-01), Smyth, Jr. et al.
patent: 5402077 (1995-03-01), Agahdel et al.
patent: 5428298 (1995-06-01), Ko
patent: 5433797 (1995-07-01), Erb et al.
patent: 5471151 (1995-11-01), DiFrancesco
patent: 5475318 (1995-12-01), Marcus et al.
patent: 5483741 (1996-01-01), Marcus et al.
patent: 5486280 (1996-01-01), Bullock, IV et al.
patent: 5487999 (1996-01-01), Farnworth
patent: 5506514 (1996-04-01), DiFrancesco
patent: 5584983 (1996-12-01), Pruyn
patent: 5642055 (1997-06-01), DiFrancesco
Benhenda, S. et al., “Effect of Pulse Plating Parameters On Electrical Contact Behavior of Nickel Coatings”,IEEE Transactions on Components, Packaging, and Manufacturing Technology—Part A(Jun. 1994) 17(2):303-308.
Bryant, Michael D., “Resistance Buildup in Electrical Connectors Due to Fretting Corrosion of Rough Surfaces”,IEEE Transactions on Components, Packaging, and Manufacturing Technology—Part A(Mar. 1994) 17(1):86-95.
Law, Henry H. et al., “Electrical Contact Phenomena of Nickel Electrodeposits with Sharp Micro-Asperities”,IEEE Transactions on Components, Hybrids, and Manufacturing Technology—Part A(Sep. 1991) 14(3):585-591.
Thoma, Martin, “A Cobalt/Chromic Oxide Composite Coating for High-Temperature Wear Resistance”,Plating and Surface Finishing(Sep. 1994) pp. 51-53.
Tomaszewski, T.W. et al., “Codeposition of Finely Dispersed Particles with Metals”,Plating(Nov. 1969) pp. 1234-1239.
Zahavi, Joseph et al., “Properties of Electrodeposited Composite Coatings”,Plating and Surface Finishing(Jan. 1982) pp. 76-82.
Fish & Richardson P.C.
Jones Deborah
Kulicke & Soffa Industries Inc.
Savage Jason
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