CA1248366A - Silver rich materials for low current contacts - Google Patents

Silver rich materials for low current contacts

Info

Publication number
CA1248366A
CA1248366A CA000482697A CA482697A CA1248366A CA 1248366 A CA1248366 A CA 1248366A CA 000482697 A CA000482697 A CA 000482697A CA 482697 A CA482697 A CA 482697A CA 1248366 A CA1248366 A CA 1248366A
Authority
CA
Canada
Prior art keywords
silver
gold
palladium
content
atomic
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.)
Expired
Application number
CA000482697A
Other languages
French (fr)
Inventor
Horst Heidsiek
Hartmuth Schmidt
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.)
Evonik Operations GmbH
Original Assignee
Degussa GmbH
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 Degussa GmbH filed Critical Degussa GmbH
Application granted granted Critical
Publication of CA1248366A publication Critical patent/CA1248366A/en
Expired legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01RELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R13/00Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
    • H01R13/02Contact members
    • H01R13/03Contact members characterised by the material, e.g. plating, or coating materials

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  • Contacts (AREA)

Abstract

ABTRACT OF THE DISCLOSURE
Silver rich materials for low-current contacts which consist of 45 to 72 atomic % of silver, 9 to 32 atomic % of gold, 9 to 32 atomic % of palladium and 0.01 to 1 atomic % of iridium and/or osmium, 0 to 10 atomic % of copper and 0 to 5 atomic % of lead and/or 0 to 5 atomic % of tin are described. On selecting the contents of silver and gold and/or gold and palladium and/or silver and palladium such that the atomic ratios are like 2:1, 3:1, 4:1, 5:1, 6:1 and/or 1:3, 1:2, 2:3, 1:1, 3:2, 2:1, 3:1 and/or 2:1, 3:1, 4:1, 5:1, 6:1, relative to each other, then materials which are very resistant to forming films of foreign material and have a high resistance to wear are obtained.

Description

The present invention relates to silver rich materials for use in low current contacts, particularly for plug connec-tions and sliding contacts. Said materials are applied in a thin layer via an intermediate layer of nickel on a support of base metal and consist of 45 to 72 atomic ~ o~ silver, g to 32 atomic % of gold, 9 to 32 atomic % of palladium, 0.01 to 1 atomic % or iridium and/or osmium, o to 10 atomic % of copper and/or 0 to 5 atomic % of lead and/or o to 5 % of tin.

So-called plug connectors are present in electronic devices to a substantial extent. At reliable contact making they assure a rapid exchange of defective structural components. As the output capacity of electronic devices increases the require-ments which the materials of these plug connectors must satisfy are changing. The resistance to the formation of films of for-eign material on the contact surface caused by delet0rious sub-stances of the environment is of prime importance. Furthermore, the materials must have a high resistance to wear which must assure a long life time without wear-through despite a layer thickness of only a few ~ m. The price of the material also is an important factor.

While only a few years ago sometimes very substantial electric loads flowed via the contacts, today frequently only ~5 minimal currents and voltages are transmitted in the micro or nano range. Furthermore, the increasing miniaturization of the structural components and thus also of the plug connectors on the one hand and the increasing air pollution on the other have intensified, to a considerable e~tent, the problem of resistance of the applied contacts to tarnish. While heretofore films of foreign material possibly present on the contact pieces could easily be destroyed by the voltages applied by so-called fritting or they could~be mechanically interrupted by the high contact forces without~trouble the voltages applied today or the contact *
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forces which are subs-tantially reduced by the increasiny minia-turization are no longer sufficien-t for -this kind of self-purifica-tion of the contacts. ~rherefore, -the resistance to a formation of films of foreign material which frequently are not even opti-cally visible has become the most impor-tant criterion of modern contact materials for plug connectors.
Of course, these requiremen-ts can be satisfied by alloys having high gold contents and particularly alloys of gold and silver containing more than 70~ by weight of gold have been found satisfactory. However, high-carat alloys containing copper and/or nickel in addition to gold and silver are also known bu-t even these alloys frequently are not sufficiently resistant to corrosion despite their high gold content.
The likewise important resistance to wear is de-termined not only by the properties of the contact materials, as for example, their hardness, but it equally depends on both the con-tact mating and the construction of the plug connector system, particularly on the contact making force. In fact, by alloying with base metals the resistance of the ma-terials to wear can ~0 generally be increased but the tendency to form a film of foreign material is thus also increased. However, materials resistant to the formation of films of foreign material normally display a poor resistance to wear.
Considering the high prices of noble metals, particu-larly of gold, the costs of the ma-terials are increasingly impor-tant. Therefore, attempts have been made to keep the gold conten-t in -these materials as low as possible.
Therefore, contact materials which are based on gold-silver-palladlum and are dlstinguished by a good resistance to tarnishing at a simultaneously reduced gold conten-t are known from DE-OS 26 37 807 and D~-OS 29 40 772. However, they contain a few percent of~base metals, such an indium, tin or nickel, in
- 2 --, .. .

addition to at least 35~ by weight of gol~. However, the base metal constituents impalr the optimal resistance of the pure noble metal alloy to tarnishing and increase the crystallization temperature of the contact material and this can result in diffl-culties during further processing. Furthermore, the wear resis-tance of these materials is not adequate.

Contact materials which contain 10 to 58% by weight of silver, 32 to 58.5~ by weight of gold, small amounts of rhodium and/or iridium and up to 3% by weight of copper, nickel or indium in addition to palladium as the balance are disclosed in EP-OS
82647. With regard to formation of films of foreign material and resistance to wear these contacts show no optimal ~ualities either.

Therefore, the present invention provides silver rich materials for use in low current contacts, particularly for use in plug connections and sliding contacts, said materials being applied in a thin layer via an intermediate layer of nickel on a support of base metal and consisting of 45 to 72 atomic % silver, 9 to 32 atomic % of gold, 9 to 32 atomic ~ of palladium, 0.01 to 1 atomic ~ of iridium and/or osmium, 0 to 10 atomic ~ of copper and/or 0 to 5 atomic % of lead and/or 0 to 5 atomic % of tin.
These materlals should be as resistant as possible against forma-tion of films of foreign material and they should have a resis-tance to wear as high as possible. It should be possible to apply them readily onto the support material and they should show no substantial increase of the electric contact resistance even at lengthy storage and exposure at 125C.

According to the present invention the contents of sil-ver and gold, relative to each other, are in an atomic ratio of 2:1, 3:1, 4:1, 5:1 or 6:1 and/or the contents of gold and palla-dium, relative to each other, are in an atomic ratio of 1:3, 1:2, 2:3, 1:1, 3:2, 2:1 or 3:1 and/or the contents of silver and ~ ~:'. ' . , :
, :
3~;i6 palladium, relative -to each other, are in an atomic ratio of 2:1, 3:1, 4:1, 5:1 or 6:1.
Preferably two noble me-tal matings are in said atomic ratio relative to each other in each case, i.e., -the con-tents of gold and palladium together with -the gold and silver and the conten-ts of gold and palladium -together with -the con-ten-ts of sil-ver and palladium.
Surprisingly it has been found that despite their high silver content silver-gold-palladium alloys show, in the range claimed, a substantial improvement of their properties with re-gard to resistance to formation of films of foreign ma-terial and wear resistance when the atomic propor-tions of gold, silver and palladium are in the specified ratios relative to each other.
The additons of base metals are advantageous primarily when the two con-tact pieces of a contact pair are made of the same material.
Because of their high silver content these materials are more favourable pricewise than the gold-silver-palladium materials known heretofore. They can be readily worked and do not undergo any increase of the electric contact resistance at lengthy exposure at 125C.
The following Table shows a numer of examples of alloys within the scope of the present lnvention.
For this purpose the alloys were metled from the metals and processed into test specimens. The increase of the contact resistance was determined after 21 days after exposing the test specimens durlng this time to a gas mixture of purified air with 0.5 p.p.m. of hydrogen sulphide and 0.5 p.p.m. of sulphur dioxide at an atmospheric humidity of 75~ at 30C.

, 3~2'~3~
No. Composition in atomic % Increase of the contact resis-tance Ag Au Pd Ir/Os Cu Pb Sn [m 1 59.81 26.73 13.38 0.03 4.3 2 53.56 30.94 15.47 0.03 2.7 3 61.90 12.69 25.38 0.03 3.5
4 50.95 29.42 19.6 0.03 3.0 58.04 16.77 25.16 0.03 1.5 6 54.99 22.49 22.49 0.03 2.1 7 63.33 18.32 18.32 0.03 6.5 8 49.99 24.99 24.99 0.03 2.8 9 54.59 18.17 27.26 0.03 2.5 57.13 14.28 28.56 0.03 1.5 11 59.99 9.99 29.99 0.03 2.2 12 59.99 19.99 19.99 0.03 2.0 13 66.66 11.10 22.21 0.03 7.6 14- 70.58 11.75 17.64 0.03 3.3 54.54 27.26 18.17 0.03 4.5 16 57.13 28.56 ~4.28 0.03 2.0 17 66.66 22.21 11.10 0.03 4.0 18 59.99 29.99 9.99 0.03 1.9 19 64.27 14.28 21.42 0.03 1.9 62.49 24.99 12.49 0.03 3.0 21 61.53 15.37 23.07 0.03 2.3 22 66.66 13.32 19.99 0.03 3.0 23 46.13 23.07 23.01 0.04 7.69 5.3 24 53.71 26.86 17.90 0.03 1.0 1.5 3.8 52.15 26.08 13.04 0.04 8.69 6.2 26 59.08 29.54 9.85 0.05 0.3 1.0 3.2 27 56.23 18.74 18.74 0.06 6.23 6.8 28 53.44 17.81 26.72 0.03 2.0 4.5 29 64.99 22.49 12.49 0.03 72.0 59.99 17.49 22.49 0.03 68.0 31 53.97 21.00 25.00 0.03 57.3 132 1 5 .97132.'9 12.51 1 ~ 89 , ~

~83~:~6 In the alloys 1 -to 7 gold and palladium are in ~the preferred atomic ratio and in the alloys 8 to 22 gold, palladium and silver are present simultaneously. The alloys 29 to 32 are beyond the claimed atomic ratios and, therefore they show a substantially higher increase of -the contac-t resistance. All the alloys showed a high resistance to wear.

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Claims (11)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A silver rich material suitable for low current contacts which can be applied as a thin layer over an interme-diate nickel layer to carrier made of base metal consisting of 45 to 72 atom % silver, 9 to 32 atom % gold, 9 to 32 atom %
palladium, 0.01 to 1 atom % iridium, osmium, or a mixture of iridium and osmium, 0 to 10 atom % copper, 0 to 5 atom % lead and 0 to 5 atom % tin and wherein at least one of the follow-ing conditions is present (a) the content of silver and gold to each other is in the atom ratio 2:1, 3:1, 4:1, 5:1 or 6:1, or (b) the content of silver and palladium to each other is in the atomic ratio 2:1, 3:1, 4:1, 5:1 or 6:1; or (c) the content of silver and gold to each other is as in (a) and the content of silver and palladium to each other is as in (b); or (d) the content of gold and palladium to each other is as in the atomic ratio 1:3, 2:3, 1:2, 1:1, 3:2, 2:1, or 3:1; or (e) the content of silver and gold to each other is as in (a) and the content of gold and palladium to each other is as in (d); or (f) the content of silver and palladium to each other is as in (b) and the content of gold and palladium to each other is as in (d); or (g) the content of silver and gold to each other is as in (a), the content of silver and palladium is to each other as in (b), and the content of gold and palladium is to each other as in (d).
2. A silver rich material according to claim 1 free of copper, lead and tin. :
3. A silver rich material according to claim 1 con-taining at least one of the elements selected from the group consisting of copper, lead and tin.
4. A silver rich material according to claim 1 con-taining gold and palladium in the atomic ratio to each other of 1:3, 1:2, 2:3, 1:1, 3:2, 2:1, or 3:1 and simultaneously containing silver and gold in the atomic ratio to each other of 2:1, 3:1, 4:1, 5:1 or 6:1.
5. A silver rich material according to claim 1 con-taining at least two of the ratios (a), (b), and (d).
6. A silver rich material according to claim 1 con-taining gold and palladium in the atomic ratio to each other of 1:3, 1:2, 2:3, 1:1, 3:2, 2:1, or 3:1 and simultaneously containing silver and palladium in the atomic ratio to each other of 2:1, 3:1, 4:1, 5:1 or 6:1.
7. A silver rich material according to claim 1 con-taining copper and wherein the ratio of gold to copper is an atomic whole number ratio.
8. A silver rich material according to claim 7 wherein the ratio of gold to copper is in the atomic ratio to each other of 3:1.
9. A low current electrical contact made of the material of claim 1.
10. A low current contact according to claim 9 which is a plug connector.
11. A low current contact according to claim 9 which is a slide contact.
CA000482697A 1984-05-30 1985-05-29 Silver rich materials for low current contacts Expired CA1248366A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3420231A DE3420231C1 (en) 1984-05-30 1984-05-30 Silver-rich materials for low-voltage contacts
DEP3420231.5 1984-05-30

Publications (1)

Publication Number Publication Date
CA1248366A true CA1248366A (en) 1989-01-10

Family

ID=6237266

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000482697A Expired CA1248366A (en) 1984-05-30 1985-05-29 Silver rich materials for low current contacts

Country Status (4)

Country Link
EP (1) EP0163904B1 (en)
JP (1) JPS60257085A (en)
CA (1) CA1248366A (en)
DE (2) DE3420231C1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000276960A (en) * 1999-03-29 2000-10-06 Nec Corp Combination electric contact, and relay and switch using it
JP2007157504A (en) * 2005-12-05 2007-06-21 Matsushita Electric Works Ltd Micro relay

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2637807C3 (en) * 1976-08-21 1981-11-19 W.C. Heraeus Gmbh, 6450 Hanau Use of a gold alloy for low-voltage contacts
DE2940772C2 (en) * 1979-10-08 1982-09-09 W.C. Heraeus Gmbh, 6450 Hanau Low-voltage electrical contact
WO1983002195A1 (en) * 1981-12-10 1983-06-23 Anderton, David, James Light duty corrosion resistant contacts
DE3345162C1 (en) * 1983-12-14 1984-11-15 Degussa Ag, 6000 Frankfurt Materials for weak current contacts

Also Published As

Publication number Publication date
EP0163904A2 (en) 1985-12-11
JPS60257085A (en) 1985-12-18
EP0163904A3 (en) 1986-12-30
EP0163904B1 (en) 1989-02-01
DE3420231C1 (en) 1985-01-03
DE3568103D1 (en) 1989-03-09

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