EP0188444A1 - Contacts electriques comprenant un alliage de palladium et connecteurs composes de ces contacts. - Google Patents

Contacts electriques comprenant un alliage de palladium et connecteurs composes de ces contacts.

Info

Publication number
EP0188444A1
EP0188444A1 EP19850902808 EP85902808A EP0188444A1 EP 0188444 A1 EP0188444 A1 EP 0188444A1 EP 19850902808 EP19850902808 EP 19850902808 EP 85902808 A EP85902808 A EP 85902808A EP 0188444 A1 EP0188444 A1 EP 0188444A1
Authority
EP
European Patent Office
Prior art keywords
alloy
contact according
layer
weight percent
base metal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP19850902808
Other languages
German (de)
English (en)
Other versions
EP0188444B1 (fr
Inventor
Everett Joseph Canning Jr
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Corp
Original Assignee
American Telephone and Telegraph Co Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by American Telephone and Telegraph Co Inc filed Critical American Telephone and Telegraph Co Inc
Publication of EP0188444A1 publication Critical patent/EP0188444A1/fr
Application granted granted Critical
Publication of EP0188444B1 publication Critical patent/EP0188444B1/fr
Expired legal-status Critical Current

Links

Classifications

    • 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
    • H01H1/023—Composite material having a noble metal as the basic material

Definitions

  • This invention relates to electrical contacts useful in connectors as well as other applications, such as in voltage regulators, relays and switches. Background of the Invention
  • the composition should be non-fusing with the mating contact material and have a low, ohmic, contact resistance with a relatively small contact pressure.
  • the material must be capable of maintaining the low resistance after a large number of operations over an extended life period.
  • the contact materials employed in the past are the precious metals such gold, palladium and platinum and alloys of such metals with each other as well as with metals such- as silver and nickel. It is often found that the contact or connector is multi-layer or inlayed type structure.
  • a gold-palladium-silver based alloy has been developed for use as an inlay in contact connector applications.
  • the inlay comprises a relatively inexpensive base metal strip having a channel cut out of the strip into which channel has been inlayed the desired contact metal alloy.
  • Typical base metals are copper, brass, Cu-Be and Cu-Ni-Sn alloys, as well as stainless steel and other spring metal alloys.
  • This invention is an electrical contact suitable for use in connectors and other devices such as relays, switches, voltage regulators and the like comprises a base metal having thereon a noble-metal alloy represented by the composition:
  • the alloy may be in the form of a multi-layer metal tape comprising said alloy which tape can be clad to or inlayed in a base metal to form a contact.
  • the contact alloys embodying the present invention generally exhibit improved wear characteristics due to an increase in hardness, but yet still exhibit sufficient ductility for use in metal cladding, inlaying or welding to a base metal for electrical contact applications. Further, these alloys generally have superior wear characteristics, they can be used in thinner layers than prior art noble metal alloys, thereby reducing the cost of the contact and connector or other device employing these alloys. In addition, since a large part of the alloy is comprised of a non-noble metal, the cost of the alloy even at the same thickness as prior art alloys is reduced.
  • FIG. 1 is a graphical representation showing the Vickers hardness versus ductility, as measured by percent reduction of thickness of rolling without cracking, of alloys in the novel alloy system as compared to a prior art R156 alloy;
  • FIG. 2 is a graphical representation of a recrystallization study of a novel alloy in accordance with this invention as compared with the prior art R156 alloy and represented as a graph of anneal temperature versus Vickers hardness;
  • FIG. 3 is a plot showing properties of a Pd-Co-Ru ternary alloy system
  • FIG. 4 is a partial isometric elevational view of a tape employing the alloys of this invention.
  • the tape is suitable for caldding and forming inlays for metal contacts for connectors;
  • FIG. 5 is a drawing representing what the inventor believes to be the effect of annealing on the hardness and chemical composition of a typical metal tape as shown in
  • FIG. 4
  • FIG. 6 is a partially cut-away isometric view of a connector having a contact employing the novel alloy of the invention; and FIG. 7 is a side elevational blow-up of the contact protion of the connector of FIG. 6.
  • the electrical contacts embodying this invention which may be employed in connectors and other electrical devices requiring electrical contacts, are comprised of a hardened palladium alloy.
  • the alloy composition is generally present as an inlay, cladding or other type coating over at least a portion of a base metal forming the electrical contact.
  • the alloys may be one layer of a multilayer tape. Such a tape can then be used for cladding, bonding, welding or inlaying to a base metal.
  • Such base metals are typically metals such as copper, brass, copper-beryllium and copper-nickel-tin-alloys as well as stainless steel or other spring metal alloys.
  • the alloys of the invention may be represented by the following composition wherein the numerals represent weight percent of the components:
  • the alloys are suitable for use either with or without gold or gold alloy top layers. Based upon the improved hardness and ductility of the novel alloys as compared with the currently employed commercial R156 alloy, it is expected that contacts made from these novel alloys will also have superior wear properties. It is contemplated that the new alloys are particularly suitable as an inlay material and therefore their ability to be rolled without cracking, i.e., their ductility, is important to the formation of such metal inlays or of cladded contacts. Also, the recrystallization behavior and ductility of the new alloys which are important to metal inlaying or cladding are at least equal to that of the prior art alloy.
  • the ductility as measured by percentage deformation by rolling without cracking versus the Vickers hardness of Pd-Co-Y alloys wherein Y is Ru, W or B, one of the alloy systems in accordance with the present invention is shown in comparison to the prior art R156 alloy. It can be seen that for any given ductility i.e, percentage reduction in thickness by rolling, the new alloys generally have a higher Vickers hardness than R156. Correspondingly, for any given Vickers hardness the new alloys are more ductile than the prior art alloy.
  • the Vickers hardness of the novel alloy is greater than that of the referenced prior art alloy at any given anneal temperature.
  • the particular novel alloy shown in fact, has a lower hardness than novel alloys with more Ru as well as many other alloys included in the claimed alloy systems. It has been found that when the palladium is alloyed with cobalt (no copper), the preferred additive is ruthenium in a quantity of from 0.5 to 5 weight percent.
  • the preferred additive is boron in a weight range of from 0.05 to 0.10 weight percent.
  • the ruthenium, tungsten and niobium which are suitable additives to a palladium-cobalt alloy to achieve the desired properties of hardness and ductility, are not as suitable for a palladium-copper alloy due to their relative insolubility in such an alloy and the brittleness of the resulting ternary alloy. Further, in order to ahcieve the desired combination of hardness and ductility so as to allow the alloyed material to be rolled without cracking, one should stay within the weight percent ranges as previously set forth.
  • the preferred amount of tungsten added to the palladium-cobalt system is 0.5 to 2 weight percent, while the preferred amount of boron in that system is 0.1 to 0.25 weight percent.
  • the preferred amount of iridium added to a palladium-copper alloy is from 0.25 to 1 weight percent.
  • the particular amounts of materials for achieving optimum performance will depend upon the ratio of palladium to cobalt and palladium to copper, respectively.
  • FIG. 3 is an example showing the relative brittleness of one of the preferred ternary alloy systems, namely, the palladium-cobalt-ruthenium system. As can be seen from the figure, as one goes above 5 wt. % Ru (outside the ranges set forth herein) , the brittleness of the alloy increase above that which is desirable.
  • novel alloys can be prepared by simply melting the constituent components together to form a homogeneous molten solution, casting the solution onto an appropriate mold and then allowing the solution to cool so as to solidify the melt.
  • a laminar structure metal tape 1 comprising the novel alloy as one of the layers.
  • This tape is particularly suitable for cladding to or inlaying in a base metal such as a spring metal alloy base metal.
  • the tape 1 comprises three layers.
  • the top layer 2 is made of either a gold or gold-silver or gold-silver alloy doped further with carbon, carbides, nitrides, boron or borides. Examples of suitable nitrides, carbides and borides are boron nitride, titanium carbide and tantalum nitride.
  • the top layer 2 is to act as an inert surface layer to inhibit corrosion, that layer should generally be between
  • x 10 -5cm to 7.62 x 10-5cm 5 micromches to 30 microinches
  • Such a layer is generally termed a gold cap layer.
  • the top layer 2 a flash gold coating which acts predo inatly as a lubricant while only giving minimal corrosion resistance.
  • Such layers are generally from 1.27 x 10 to 6.35 x 10 —6cm (0.5 to 2.5 microinches) in thickness.
  • the second layer 4 of the tape 1 is a layer of the novel alloy as set forth herein.
  • the preferred alloy for such a tape is 65 wt. % Co, 33 wt. % Pd and 2 wt. % Ru.
  • this second layer 4 is from 3.81 x 10 -5cm to 5.08 x 10 -4cm (15 to 200 microinches) in thickness.
  • Underlying and in contact with the second layer 4 is a bottom layer 6 made of nickel.
  • the nickel should be a high purity nickel (99.9 + %) so as not to add contaminants to the second layer 4 upon annealing.
  • the thickness of the nickel layer 6 may be any desired thickness, but is typically from 3.81 x 10 -4cm to 11.43 x 10 -4cm (150 -to 450 microinches).
  • the nickel layer 6 serves several pruposes. First, the nickel layer 6 acts as a base material for the thin gold cap and palladium alloy layers. Secondly, the nickel layer 6 enhances the bondability of the tape 1 to the underlying base metal material. Thirdly, it prevents base metal atoms and impurities from diffusing up into the palladium alloy layer 2 after the tape 1 is clad to the base metal.
  • a fourth layer (not shown) between the palladium alloy layer 4 and the bottom nickel layer 6 to further insure that the ruthenium and cobalt or the like in the palladium alloy layer 4 does not diffuse into the nickel layer and underlying base metal.
  • This optional layer is preferably a thin silver layer or a thin layer of a silver alloy.
  • one can bond the novel alloy directly to a base metal, the tri-l ' ayer structure merely being the more generally preferred structure for a tape to be clad or inlayed to a base metal.
  • the tape is annealed typically at temperatures of from 600°C to 850°C for times of from 0.5 to 60 minutes. During such annealing, there is a diffusion of constituents between layers and the relative hardness as well as the composition of the layers is effected. If one refers to FIG. 5, there is depicted the relative hardness and chemistry of each of * the three layers 2, 4 and 6 before annealing and then again after annealing of a Pd-Cu-Ru alloy, showing the change in hardness and chemistry of the layers due to annealing.
  • the chemistry of the layers changes upon annealing due to the diffusion of some of the gold into the underlying palladium alloy layer 4 and some of the palladium diffusing into the gold layer 2. Diffusion into the underlying nickel layer 6 which acts as a diffusion barrier for components in the base metal strip, is not considered. Further, there is only minimal diffusion of ruthenium and cobalt into the gold layer 2 from the Pd alloy layer 4. Also, the Co is believed not to effectively diffuse into the gold layer beyond the equilibrium Co in gold concentration which may be controlled by the annealing temperature. With respect to the hardness, a change in the hardness profile can be seen partially due to the diffusion and partially due simply to the effects of the annealing temperature. Referring now to FIG. 6, there is shown a connector
  • FIG. 7 is a blow-up of the contact 14 portion of the connector 10.
  • the connector 10 as shown, comprises a plastic body 12 encasing a plurality of spaced external elongated contacts 14 for interconnecting the connector 10 to various other devices or circuits.
  • the contacts 14 are embedded within cavities provided therefor within the plastic terminal block or insulating body 12.
  • the contacts 14 have a solder coated tail 16 which extends out of the body 12 and a head portion 18 having a multilayer metal alloy tape 1 inlayed therein.
  • the contacts 14 extend transversely within the connector 10 and are registered with a port or hole 22 on the side of the connector 10 or opposite the contact tail 16 for accepting a connector pin 24, e.g., from another circuit source.
  • the contact 14 is better shown with the reference to FIG. 7 which shows a side view of a connector contact 14.
  • the base 20 of the contact 14 is made primarily of a resilient or spring alloy composition, e.g., a Cu/Ni/Sn alloy.
  • Extending transversely along the tip of the head 18 of the contact 14 is the metal inlay tape 1.
  • the inlay tape 1 is a tri-layer tape as previously described with reference to FIG. 4. This tape 1 was rolled bonded into a channel scribed in the base metal. The base metal was then punched and formed as is well known in the art to result in the connector contact shown.
  • EXAMPLE 1 EXAMPLE 1
  • the manufacture of the triclad tape starts with metal strips of each material to be bonded together, i.e., gold, novel alloy and nickel whose thickness represent the general thickness ratio of the final composite tape.
  • the surfaces of the metal strips to be bonded are degreased, cleaned and scratch brushed to roughen the surfaces in order to improve the bonding capabilities.
  • the scratch brushed surfaces are then recleaned to remove debris from the scratch brushing operation.
  • the triclad tape can be manufactured in one step by alignment of the three strips stacked in the appropriate sequence and roll bonded together. Each strip should have a tack tension applied to it as it is being rolled to insure consistent rolling behavior and uniform product thickness.
  • the exact layer thickness depends upon the levels of back and front tensions, strip iniital thickness, strip material, percentage of deformation, use of lubrication, rolling pressure and amount of slippage between strips.
  • the triclad tape can be manufactured in two steps by first bonding one pair of metal strips, i.e, the gold and hardened palladium alloy, and then bonding the bi-metal strip to the nickel.
  • a minimum reduction in thickness is required to achieve any bonding between two metal strips and the required minimum amount is a function of the metal (alloys) and rolling temperatures.
  • a reduction of 45-65% is required.
  • the strips are annealed at about 700-850°C to further increase the bond between metal layers and to soften the metal for further processing.
  • the triclad tape can then be slit into the desired width and cut to length for metal inlaying or cladding to the base metal strip. More than one strip can be inlayed or cladded to a wide base metal strip at one time to allow for production of multiple strips which may have multiple inlays on its surfaces.
  • the novel palladium alloy can be bonded to the nickel strip and the gold surface layer can be applied either before or after inlaying/cladding into the base metal strip by plating, sputtering or some other process.
  • Annealing the bonded strip is dependent upon the composition of the metal layers. Nickel can be fully annealed at 600°C for 5-15 minutes; the novel palladium alloys can be annealed in the temperature ranges of from 600-850°C.
  • the most critical anneal for interdiffusion of elements between metal layers occurs when the layers are in the final base metal strip configuration just prior to the final rolling to achieve the desired temperature in the base metal strip. It is at this point in the processing when interdiffusion between layers is critical due to the very thin layer thicknesses.
  • Cladding is typically defined as the operation where metal strips are joined by rolling together while the inlaying process involves cutting or skiving a channel in the base metal in order to incorporate a second metal strip, or in this case, a triclad metal strip containing the novel alloy.
  • the metal inlaying process is generally preferred if the location of the second metal strip is critical or if the thickness of the inlay would be a significant proportion of the total thickness of the finished strip (i.e., greater than 15%).
  • the cleaning procedures for metal cladding the triclad strip and base metal are identical to those described earlier, whereas for metal inlaying it is not necessary for extensive base metal cleaning or scratch brushing since a new surface will be skived into the strip just prior to bonding.
  • the typical reduction to bond the nickel surface to a base metal alloy, i.e., CDA725 (a Cu- Ni-Sn alloy) is between 55-75% reduction with higher bond strength associated with the higher reduction.
  • Annealing of the inlayed composite strip is in the range of 600-850°C for the typical novel alloy inlay for 0.5 to 60 minutes to control the interdiffusion of elements.
  • the final rolling of the inlayed strip is typically 40-55% reduction to achieve the desired temperature in the (CDA725) base metal.
  • the completed base metal strip containing the metal inlay can now be slit to the appropriate width which also accurately locates the position of the inlay in reference to the strip width for ease in stamping.
  • the finished strip may be inspected and processed through a stretcher-leveler to reduce strip camber and coil set if it is necessary.
  • Other optional processes might include application of a solder top and/or bottom layer for easier assembly of parts..
  • the finished strip can then be fed into a high speed punch where the contact is stamped and formed. This is typically a reel-to-reel operation after which the formed contacts are inserted into the plastic housing of the connector and cut from the reel. Finished connectors and then inspected and tested.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Composite Materials (AREA)
  • Materials Engineering (AREA)
  • Contacts (AREA)

Abstract

Contacts électriques comprenant un métal de base sur lequel est déposé un alliage de palladium, cet alliage comprenant de 30 à 60 % en poids de Pd, de (70-b) à (40-b) % en poids de X, de 0,05 à 5 % en poids de Y, b étant le pourcentage pondéral de Y, X est sélectionné parmi Cu et Co et Y est sélectionné parmi Ru, W, B, Ir et Nb et où X est uniquement Cu, Y est au moins un élément parmi B et Ir, B étant présent en une quantité allant jusqu'à 0,25 % en poids. L'alliage peut former une partie d'une bande multicouche déposée ou incrustée sur le métal de base. Sont également décrits des connecteurs électriques incorporant ces contacts.
EP19850902808 1984-06-27 1985-05-13 Contacts electriques comprenant un alliage de palladium et connecteurs composes de ces contacts Expired EP0188444B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US62527484A 1984-06-27 1984-06-27
US625274 2000-07-25

Publications (2)

Publication Number Publication Date
EP0188444A1 true EP0188444A1 (fr) 1986-07-30
EP0188444B1 EP0188444B1 (fr) 1989-03-15

Family

ID=24505329

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19850902808 Expired EP0188444B1 (fr) 1984-06-27 1985-05-13 Contacts electriques comprenant un alliage de palladium et connecteurs composes de ces contacts

Country Status (3)

Country Link
EP (1) EP0188444B1 (fr)
DE (1) DE3568901D1 (fr)
WO (1) WO1986000461A1 (fr)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1188773A (en) * 1968-03-25 1970-04-22 Int Nickel Ltd Ruthenium Alloys.
BE770653A (fr) * 1970-08-06 1971-12-01 Heraeus Gmbh W C Utilisation d'un alliage de palladium pour des pieces de contact electriques
DE2753654C2 (de) * 1977-12-02 1982-12-23 W.C. Heraeus Gmbh, 6450 Hanau Legierung aus Palladium, Kobalt und Kupfer für elektrische Kontakte
DE3307182A1 (de) * 1982-05-26 1983-12-01 Technical Materials, Inc., Lincoln, R.I. Legierung fuer elektrische kontakte und verwendung fuer eine solche legierung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8600461A1 *

Also Published As

Publication number Publication date
EP0188444B1 (fr) 1989-03-15
WO1986000461A1 (fr) 1986-01-16
DE3568901D1 (en) 1989-04-20

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