Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
  • H01R13/02—Contact members
  • H01R13/03—Contact members characterised by the material, e.g. plating, or coating materials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H1/00—Contacts
  • H01H1/02—Contacts characterised by the material thereof
  • H01H1/021—Composite material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
  • H01H11/04—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts

Definitions

• the invention is concerned with apparatus including electrical contacts whicn depend on mechanical contact for closure.
• a category of included apparatus may be characterized as "low current” or “nonarcing" and has traditionally reiied upon gold.
• the category includes electronic devices such as wire and cable connectors, printed wiring boards, and integrated circuits.
• the invention provides for contact surfaces which depend for their electrical characteristics primarily upon chemical compounds.
• Illustrative compounds are chemically grouped as suicides, carbides, nitrides, phosphides, oorides, sulfides and selenides. Since a main objective of the invention is economic, it is compounds of platinum-group metals as well as precious metals (ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold) that are excluded.
• contacts in accordance witn the invention have low contact resistance.
• Resistivity as measured by a four point probe is no greater than about 10 -3 ohm-centimeter ( ⁇ cm).
• contact resistance is generally below about 10 milliohms. This resistance level is seen after high humidity-temperature cycling under test conditions used for qualifying telephone equipment.
• the invention contemplates the formation of thin layers of compound contact material (layers of the order of 10 micrometers or less in thickness) produced by in situ reaction with substrate material.
• Contemplated reactions which may involve vapor phase or liquid phase reactant involve at least one constituent — usually a metallic constituent — of the substrate. It is a significant aspect of the invention that such in situ formed layers may be directly substituted for gold layers deposited, for example, by electroplating, sputtering, etc.
• the invention therefore, contemplates formation of contact lasers on partially fabricated or on otherwise completed devices.
• Thin—film compound contacts of the invention are generally useful in nonarcing applications which have traditionally been served by gold. While the lower melting compounds, e.g., suifides and selenides, are generally limited to such use, others are not so limited. 1. Glossary
• in situ formable materials characterized by bulk resistivity of 10 -3 ⁇ cm or less. All such compounds are generally stable to the extent that resistivity does not increase beyond such maximum value under test conditions applied to relevant gold devices.
• In situ formation involves at ieast one constituent — usually a metallic element — contained in the substrate upon which the layer is formed. Appropriate constituents do not include platinum-group metals or other precious metals (prohibited elements are ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold).
• Contemplated conditions under which tne characteristic is satisfied are "dry circuit" conditions.
• Contemplated devices in accordance with the invention are generally nonarcing under contemplated operating conditions, as well.
• Txxis is the in situ formed contact compound in the fo rm of a layer having a thickness of the order of 10 ⁇ tn or less .
• 100 g rams is generally below 10 milliohms before or after appropriate testing , e .g . , for some purposes , at hiyh numidi ty (90 percent relative nmui ⁇ ity air at y ⁇ deg rees Fahrenheit) and temperature cycling between -40 deg rees C and +140 dec rees C .
• Structures consisted of a flat compound contact contacted by a hemispherical probe. All hemispherical probes were surfaced with soft gold (99.99 weight percent). Experiments with compound contact probes yielded approximately the same contact resistance measurements. Open circuit voltages were less than 20 millivolts resulting in currents of less than 10 milliamperes upon closure.
• the probe structure was parabolic in cross section with the contacting region approximately defining hemisphere having a diameter of one millimeter.
• Titanium was exposed to ammonia gas at a temperature o f 1100 degrees C fo r a pe riod of 1 hour r esulting in a iayer thickness of approx ima tely 8 ⁇ m .
• Resistance 50 miiliohms at 100 grams.
• Tie preparation - Titanium metal was exposed to acetylene for a period of 1 half hour at a temperature of 950 degrees C, yieldiny a layer of a thickness of about 2 inn. Resistance - 90 miiliohms at 100 grams.
• Example 5 Composition — Copper Selenide, CuSe.
• Composition Copper Sulfide, CuS. Preparation — A 80 percent copper, 20 percent cobalt substrate was exposed to sulfur vapor at 187 degrees C using a nitrogen carrier gas for 2.5 hours. This resulted in a coating thickness of l ⁇ m.
• Example 7 The material of Example 6 was produced by an alternative technique in which reaction was with molten sulfur as well as by use of dicnlorobenzene solvent. Electrical properties were substantially identical.
• Example 7 The material of Example 6 was produced by an alternative technique in which reaction was with molten sulfur as well as by use of dicnlorobenzene solvent. Electrical properties were substantially identical.
• contact composition in accordance with the invention avoids the use of gold, silver, and metals of the platinum group (nu, Rh, Pd, Re, Os, Ir, Pt) .
• functional material in accordance with the invention is produced by in situ reaction involving at least one reactant which is present as a substrate constituent and another reactant introduced externally.
• Tne externally introduced reactant is generally in fluid form, either vapor or liquid. Introduction may involve a carrier, for example, to introduce the external reactant in the vapor phase but permit reaction at a temperature below its vaporization temperature.
• An aspect of the inventive teaching depends upon the concept of replacing a thin layer of conventional contact material - generally gold - with a layer of a chemical compound.
• An important teaching permits substitution of the one layer for the other and thereby minimizes or avoids device redesign.
• Formation of gold or gold-containing layers in prior art devices is by disposition - e.g., by electroplating. Formation of the compounds of the present invention is accomplished Dy in situ reaction.
• the invention does not depend upon designation of compound composition.
• the technical literature includes reports of compounds wi tu measured electrical properties and known stability in some encountered ambients so, for example, titanium nitride has been studied to result in a literature reference, 1980 Proceedings of the Electrochemical Society, 316 (1979) , reporting bulk resistivity values of 50 ⁇ cm.
• the compound is known to be stable in usual air ambient over usually prescribed temperature ranges of operation.
• Wuereas compounds with requisite electrical properties are generally of known stability in air ambient, i.e., in O 2 , N 2 , and H 2 0, otuer considerations may well require screening.
• Compounds tested in the work which led to this disclosure have manifested stability in the presence of sulfur bearing ambient material, H 2 0, SO 2 , SO 3 , H 2 S, as well as in Cl 2 and HCl.
• electrical properties of contacts produced in accordance with the invention are primarily due to the compounds noted. Reaction may involve more than two reacta ⁇ ts, e.g., may proceed by reaction of an external reactant with two or more suostrate constituents, e.g., where both yield compounds otherwise appropriate for the practice of tne invention.
• contacts produced in accordance with the invention will at least in initial stages contain little if any material in addition to the contemplated compound/s.
• structures may include unintentional material.
• Examples include substrate ingredients which under fabrication conditions migrate into the compound layer sometimes to the free contact surface. Resulting mixture, again consistent with prior experience, may result in improvement of the contact surface.
• analysis of the free contact surface has revealed presence of 2 weight percent cobalt.
• Studies of the nominal composition CuS showed increased resistivity upon inclusion of tin, iron, zinc, manganese, titanium, chromium, nickel, aluminum, silicon, antimony and cobalt in solid solution (all were in the range of 1- 15 weight percent).
• the contact-compound rich phase is desirably composed of at least 85 percent of compound/s in accordance with the inventive teaching.
• Second phase modifications which may involve elements or compounds to the extent not dissolved in the contact compound rich phase have only a linear effect on contact resistance and may be tolerated in larger amounts.
• Such second phase may be unintentional or may be introduced deliberately in order to modify physical characteristics.
• such second phase should be present only in an amount to occupy up to 30 percent of the free surface area. To a first approximation under usual circumstances, this limit may be expressed as weight percent.
• Intentional modification of composition includes constituents added after formation of the compound. Examples include gold diftusion to produce a graded structure of good electrical and mechanical properties. Structures may also be graded by altering reactant composition during reaction.
• FIGS. 1A, 1B, 2A, 2B, 3 and 4 are perspective views of nonarcing contacts incorporating in situ formed compound contact layers of the invention. Detailed Description
• FIGS. 1A and 1B are cross-sectional elevational views of a wire connector of a design used for telephone handset interconnection. It consists of wires 10 contained in recess 11 and molded in detail 12 to terminate in spring portions 13 provided with contacting surface 14 produced in accordance with the invention. Mating wires 15 are mechanically fixed in position by locking inserts 16 and 17 and terminate in spring portions 18, also surfaced with a compound contact layer of the invention. Upon inserting portion IB in 1A as shown by arrows 19, spring portions 14 and 18 are Drought into mechanical and electrical contact.
• FIGS. 2A and 2B are sectional and elevation views depicting a circuit board connector.
• FIG. 2A shows a printed circuit board receptacle 20 provided with a spring contact 21 having a substrate 22 and contact layer 23 in accordance with the invention.
• circuit board 25 of FIG. 2B is inserted into recess 24 of receptacle 20.
• Contact is completed when compound contact 26 engages contact layer 23.
• Contact 26 is produced by in situ reaction with substrate 27.
• FIG. 3 is a sectional view of a momentary make break contact in use. Compound contact regions 30 and 31 produced on substrates 32 and 34 are brought into compressive contact upon distortion of element 33 from the configuration shown In solid outline to the configuration shown in phantom.
• FIG. 4 is an elevation view of a wire wrapped connector consisting of post 40 provided with compound contact layer 41.
• Wire 42 may be conventional gold plated, or surfaced with a layer in accordance with the invention.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Contacts (AREA)
• Coupling Device And Connection With Printed Circuit (AREA)
• Parts Printed On Printed Circuit Boards (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=23164993

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Family Applications After (1)

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Citations (3)

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• 1982
  • 1982-08-26 WO PCT/US1982/001156 patent/WO1983000945A1/en not_active Application Discontinuation
  • 1982-08-26 EP EP19820903006 patent/EP0088123A4/de not_active Withdrawn
  • 1982-08-26 JP JP50297982A patent/JPS58501434A/ja active Pending
  • 1982-09-09 EP EP82108330A patent/EP0074630A3/de not_active Withdrawn
  • 1982-09-09 ES ES515607A patent/ES8401818A1/es not_active Expired
  • 1982-09-10 GB GB08225893A patent/GB2110197B/en not_active Expired

Patent Citations (3)

Non-Patent Citations (1)

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