WO2013142765A1 - Silver antimony coatings and connectors - Google Patents

Abstract

The invention, concerns conductive coatings for use in the manufacture of for example, electrical connectors, LED arrays, and lead frames used in the computer industry. The coatings are composed of silver, antimony, and a protective layer composed of a fluoropolymer.

Description

SILVER ANTIMONY COATINGS, CONNECTORS, AND PROCESSES

FOR MAKING THE SAME

FIELD OF tHE INVENTION

The Invention concerns conductive coatings for use In the .manufacture', of, for example, electrical connectors, LED arrays, and lead frames used in the computer industry.

BACKGROUND OF THE INVENTION

Electrical connectors are composed of a. first body, typically metal, that is mechanically inserted into or otherwise contacted with a second bodyy also typically metal, The electrical connection is enabled by the contact of an interface of the first body with an interface of the second, body, The materia! properties of these interfaces are crucial for the performance of the connection and the connector. The connectors must exhibit good electric contact, .e., low contact resistance, generally less than 10 rn-ohm, and stability. Ideally, the low contact res.ista.nce should not change with aging.

The connectors roust also exhibit good wear resistance. What is good wear resistance depends on: the purpose for which the cornice tor is used. Some connectors have to sustain only a fe Cycles durin their lifetime; with cycles being defined a the number of times the connectors are contacted (or mated) and released. A light bulb and its socket is an example of this type of connection and connectors. Some connectors have to withstand up to hundreds and thousands of cycles, for sample, in the case of appliance plugs and sockets. Wear resistance i measured by the co-efficient of friction (COP) of the connectors. Preferably, the coefficient of friction should be less than 0.8 after 50 mating cycles, in micro-electronic applications, with lower voltages and lower currents, the requirements are specially demanding: typically contact resistance of less then 10 mi!iioh ns with load forces from 10 -700 grams,

The connectors also must exhibit good corrosio resistance. As the connector's properties should stay constant during the lifetime of the connector, Tl-A0.Q0.6P corrosion would have negative effects on contact resista.n.ee_:1 wear resistance and. appearance. Preferably, minimal to no corrosion, should be observed, upon, subjecting the connector to the Mixed Flowing Gas (MFC) test, in. aoeordariee with industry standards (for example, standard EiA-364-65B_i Class IIA; Temperature; 30°C +/~ Γ;; Relative Humidity: 70% +/- 2%; Cb .: 10 + /·· 3 ppb: ¾ S: 10 +/-^■ _**? ppb )s: 200 +/- 50^■ ppb: SO3: 100 -f /- 0 ppb).

Most electrical connector nterfaces are prepared by electro- depositing layers of metals onto the body of the connector., A typical, interface may be composed of a bronze body as a substrate layer onto which a barrier layer of nickel is electroplated. Onto the barrier layer a contact layer i then electroplated. Alternatively, the contact, layer may be applied using a molten bath method. See for ex mple United States Patent No. 5,075,176, which discloses tin allo electrical connector contact layers containing 0. 1 to 8,5% by weight of silver, nlunhnuni, silicon, copper, .magnesium, iron, nickel, manganese, sine., rconiurn., antimony, rhodium, palladium, and/or platinum precipitated .from a molten bath, and havin a. thicknes of 0,3 to 12 microns (pro).

Gold, ha been, the metal of choice for the contact layer of electrical connectors because of its superior wear resistance and excellent corrosion resistance, especially for connectors that must be inserted and removed, multiple times over their useful life. The high cost of gold however has caused the Industry to try to substitute other conductive .finishes to replace gold, especially on connectors.

Because silver Is the most conductive of ail metals, it has been investigated as a. substitute for gold on plated electronic connectors and contacts.. Pure sliver however forms a. ^'silver, sulfur-rich, purple discolored, surface under ambient atmospheric conditions that, over time, grows to a thickness that can Increase the contact resistance above the specification of the device in which the connector is used. Silver also has poor wear characteristics because of its cold fretting (cold welding) properties, i.e., upon .insertio and removal silver metal can be transferred from one part of the connector to another. Thus, the use of silver ha.s been limited due to the tendency of tarnishing when unprotected and exposed to the atmosphere. In addition., wear resistance is insufficient as pure silve is too soft and silver friction on silver leads to cold welding, i.e. fretting. See Tl-A0.Q0.6P

M. Myers j Overview of the Use of Silver in Co^'nncctor Applications, Tyco Electronics Technical Paper, February 5, 2009, No, S03- 10I6, rev. O.

Industry standards and tests have been used to test the gold deposits for wear resistance and contact resistance at set atmospheric conditions and under higher temperature for harsh service conditions. These standard tests are used to. evaluate the deposited contact materia!., Wear resis an e is measured by co -efficient of friction (COF) and. corrosion resistance is measured by contact resistance (OR). Silver and silver alloys ^'have been tested, for wear resistance and corrosion, resistance and compared with, the test results from the gold deposits with varying results, M.

Antimony is a silvery, lustrous gray metal that has Mo s scale hardness of 3, It has been used for over 2,000 years. Today; its primary use, as antimony trloxide, is in the manufacture of flame-proo!lng corr.mour.vds. Alloyed with lead. It increase's its hardness and mechanical strength, ^'Lead -antimony alloys ar used in lead-acid batteries, in babbit metals, bullets,, lead shot, cable sheat.hfn.gj and as a dopant for the emitters and collectors of NP alloy junction transistors, Antimony is also used. In the semiconductor industry as a dopant for ultra-high conductivit n-type silicon wafers in the production of diodes, infrared detectors, and. Hall-effect devices. Alloyed with silver, antimony Is typically employed in bearing assembly, ballast, casting, step soldering and radS a ti o n sh i el d 1 n g ,.

Regarding silver-antimony alloys used, in the manufacture of electrical connectors. United. States Patent No, 5,6.10,347 discloses materials for electric contacts composed: of a silver matrix and a metal oxide: component present in the ^'form of oxide particles of tin oxide and zinc oxide and one of another metal oxide/carbide particles selected from antimony and other elements. Including the preferred molybdenum. The tin oxide is composed of 0,01- 10 weight percent of the othe metal oxide/carbide and i present in the contact In the amount of 5-20 weight percent_* The silver matrix includes areas of tin oxide and is free of other oxide/ carbide particles, which are confined in a boundary area between the tin -oxide particles and the sliver matrix. United States Patent No. 4, 859,238 discloses electrical contacts formed from a. silver-fron material which contains 3-30% by weight of Iron and one or more of the components manganese., copper, zinc, antimony, bismuth oxide., molybdenum. Tl-A0.Q0.6P oxide:, tungsten oxide or Chromium nitride in an amount totalin 0.05-5 weight percent, the balance being silver, P€T International Patent Publication No, WO 92 / 14282 discloses electrical contacts having superior wear characteristics comprising a member formed of copper, a copper alloy, or brass having a thick plating layer on it composed of silver and antimony, This plating layer has a thickness of at least 30 microns, preferably 40 microns, ith an amount of antimony about 1%, particularly between 0,3 and 0.7%,

Regarding sliver- ntimony alloys formed by electro-deposition.. United State Patent ^" o. 3,425,917 discloses adding antimony to a. silver cyanide electrolyte In the amo nt of between 0,01-10 g/t, preferably between 0.2-3 g/l to improve brightness and hardness. United States Patent No. 3,219,558 discloses adding up to 3 g/l antimony in combination with an alkal metal sal of methylene bis n ph alene sulfonic -acid to a conventional silver plating solution t obtain, fully bright deposits and United States Patent No. 2,777,010 discloses Improved, results by adding 0.1 - 1 .0 g/l antimon to a silver cyanide electroplating: bath to improve ^'brightness results.

Th s, there remains a. need, for an improved silver-antimony alloy for use in electrical contacts, as electric connectors, i LED arrays and in lead frames. This Invention provides such an alloy.

SUMMARY OP THE INVENTIO

We have found thai alloying silver with, antimon followed by baking at 120^*C for 100 hours lowers the hardness value of the contact layer from 175 knoop to only 145 knoop. Pure silver deposits have hardness values of 100 knoop and. 70 knoop after the I20^:5C, 100 hour hake, (This 100hr/ 120^cC bake is a standard Industry test designed to mimic the life cycle temperatures seen over the connector's lifetime when not exposed to extremel high temperatures at all times, I Also alloying silver with antimony does not sacrifice contact resistance. We also have found that application of a protective layer over the electroplated sUver-antimony layer furthe reduces the likelihood of tarnishin and Increases wear resistance without increasing electric contact resistance. Thus, electroplating a siiver™a.n imony layer as described herein, enables the use of silver alloy as an alternative to gold in electrical contac s. Tl-A0.Q0.6P

Accordingly, in one aspect the invention is n aqueous electrolyte solutio for use in electrodepositing a. silver— antimony alloy. The solution contains the following srihstances in substantially the proportions indicated:

120 g/1 Potassium Cyanide

15 g/1 Potassium Carbonate

35 g/i Silver as Potassium Silver Cyanide

4 - i O g/1 Antimony as Antimony Tartrate

25 g/I Rochelle Salts.

The electrolyte solution may also contain between 0.10 and 2.00 ppm Selenium, preferably as potassium or sodium selenoeyarude,

in another aspect the Invention Includes a method of preparing a hard silver alloy deposit on a. conductive article- in the method_* the article is used as. the cathode in. an electroplating process employing one of the foregoing ao-ueous electrolyte solutions, and: electroplating the article at a current density of between 50 and 150 asf in a preferred embodiment, the method further includes the steps of drying the electroplated article, and then immersing the article in a protective substance lor a sufficient amount of time to coat the article with the substance. The protective substance or coating is composed of either a polyphenol ether or a perlluropoiylether. Once suftlciently immersed., the article is allowed to redry so that the coaling sets and forms the protective layer a top the silver allo deposit.

In yet another aspect_s the invention includes electrical connectors comprising silver - antimony alloy containin between 2 and 8 percent antimony made in accordance with these methods, and electrical connectors comprising a. body composed of bronze or copper, a barrier layer composed of nickel, and a contact layer covering the nickel layer in which the contact layer is composed of a. silver - antimony alloy containing between 2 and 8 percent antimony. Sneh electrical connectors may also he composed of an additional, protective layer composed of a polyphenol ether or a perfluropolylether covering, the contact layer <

DESCRIPTION OF THE DRAWINGS

Figure 1 is a graphic representation of the percentage of antimony plated as a function of current density (CD) as described in Example 5. Tl-A0.Q0.6P

Figure 2 is a. graphic representation of the results of the wear resis ance test described in Example 8 for the 5% antimony deposit samples described in Examples 3 and 5,

Figure 3 is a graphic representation of the coefficient of friction (COP) results ibr 5% antimony deposit samples coated: with polyphenol ether or perf uropolylether as described in. Example 9,

Figures 4 . 5.,· and 6 axe graphic representations, of th results of the Mixed. Flowing Gas teste conducted o samples as described in Example 10.

DE AILED ^'DESCRIPTION

Si er-antimony alloys have been used to produce harder silve deposits than pur silver hut the still do not wear well because of silver's unique fretting, characteristics, (cold welding). Alloys of silver containing 0-1% antimony have been, used in decorative applications to produce mirror bright silver finishes. A. by product of alloying silver with this amount of antimony has been, better corrosion resistance on storage at. ambien conditions, but such alloys still do not approach the corrosion, resistance of gold deposits.

To this end research began on producing siiver~antimony deposits containing higher amounts of antimony for corrosion resistance. The chemistry ^•used i the typical silver cyanide bath chemistry, which can h used at the deposit speeds required to. mimic deposition speeds used for geld deposits. Using these standard plating bath formulations, which are described in Example 2, the stability of the antimony ion in sotution was inadequate and alloys containing more than 2% antimony could, not be achieved, The addition of a secondary chelate as described in Examples 3 and 4 allowed the antimony concentration in the plating bath to Increase and therefore the antimony in deposit to increase. Alloys from 3 to 10% antimony were produced when a secondary chelate was used. The deposits above 8% antimony were highly stressed and cracked. his cracking ma.ke the deposit porou and not functional. Deposits at 5% antimony had lowe stress and were not cracked. As a comparison, silve -copper alloys were also prod ced, as described in. Example 1 elow. All deposits were electroplated, on standard, plaque and probe copper base materials- having a. 2 Tl-A0.Q0.6P micron nickel suiihmate underplate. in all eases, the silver or antimony silver deposits were plated to a. thickness of 3 microns.

EXAMPLE 1. ELECTROPLA IN G OF SILVER-COPPER ALLOY

A standard silver cyanide electroplating apparatus and bath was prepared. The? electroplating .solution was as■..follows;

SO g/i Potassi um Nitrate

60 g/1 Dime thy ihydantion

30 g/I Sliver as Sliver Dlmetirylhydaution

4 g/1 Copper as Copper itrate

pH, 10,0 with Potassium Hydroxide

0.5 g/I Dipyridy!.

The bath was heated to 13CFF, and the deposit was plated at 40as.f. The deposit was white in appearance and did not crack on bending at 2.5 microns thickness. The deposit was tested for corrosion by ^'using the Ammonium. Sulfide Vapor Test, Eleetrodeposited Silver Flaring QS&-366D fsee Example 6 below). A. pure silver deposit was used, as a comparison,. Both deposits turned dark purple within a.n. hour.

EXAMPLE 2< ELECTROPLATING' OF SILVER- ANTI O Y ALLOY

An apparatus and hath was prepared as descr bed in Example 1. except that the electroplating solution wa:s as follows:

120 g/1 Potassium. Cyanide

15 g/I Potassium Carbonate

35 g/1 Silver as Potassium Silver Cyanide

5 g/l Antimony as Antimony Tartrate.

The hath was heated to 130*F, WfthiaA 30 minutes the bath turned cloudy with precipitate and antimony levels in thn bath fell. Plating felled.

EXAMPLE 3. ADDITION OP A SECOND ARY CHELATE

An apparatus and. bath was prepared as described in. ExatnpJe 1 _; except that the electroplating solution was as follows:

120 g/1 Potassium Cyanide

1 5 g/i Potassium Carbonate

35 g/I Silver as Potassium Silver Cyanide

5 g/1 Antimony as Antimony Tartrate

25 g/1 Rochelle Salts (Potassium Sodium Tartrate). Tl-A0.Q0.6P

The bath was heated to 13CTF. No precipitate or cloudiness was observed. Sample panels were plated at 100 asf. Using standard, methods, the panels were determined to contain 5% a imony and. a. bright white appearance. The deposits were bent and not cracked at 2.5 microns thickness.

EXAMPLE 4. ADDITION OF A SECONDARY CHELATE

An. apparatus and. bath was prepared, as described in Example I , except that the electroplating solution, was as follows:

120 g/l Potassium Cyanide

15 g/l Potass! urn Carbonate

35 g/l Silver as Potassium Silver Cyanide

10 g/l Antimony as Antimonv Tartrate

25 g/l ocheiie^' Salts.

The hath was heated to 130^<;F. No precipitate or cloudiness was observed. Sample panels were plated at 100 a h Using standard methods, the panels were determined to contain S% antimony_^ and a bright whit appearance. The deposits were bent and no cracked at 2.5 micron thickness.

EXAMPLE 5. ADDITION OP SELENOCYAN!DE

An apparatus and bath was prepared as described I Example 3, except that the electroplating solution, was as follows:

120 g/ί Potassium Cyanide

15 g/l Potassium Carbonate

35 g/l Silver as Potassium Sliver Cyanide

5 g/l . Antimony as Antimony Tartrate

2S^' g/i Rocheiie Salts

.25 ppm Se as Potassium Selenocyamde.

The bath was heated to I30^;>F. No precipitate or cloudiness was observed. Sample panels were plated at 100 asf. Using standard methods, the panels were determined to contain 5% antimony and a bright white appearance. Deposits were bent and not. cranked at 2,5 microns thickness.

The percentage of silver-antimony allo that was plated at various current densities {CD} i shown graphically In Figure .1. Curren densities between SO and 150 asf resulted in sllver~a.otim.ony alloys containing between about 3 -6¾ antimony. Tl-A0.Q0.6P

EXAMPLE 6. CORROSION RESISTANCE TES I G

The Ammonium. Sulfide Vapor Chamber Test, modified from the Federal: Specification for Elecirodeposited Silver Plating QSS~36$D_f. was used to test the corrosion resistance of the S% antimony silver deposits made in accord with Example 3 and Example 5. Contacts were piated. with 2,5 microns of the deposit. One ml of 20 to 2 percent ammonium sulfide (light),,, reagent grade, was pipetted into a one-liter volumetric flask. The flask was filled to the mark with distilled water and agitated thoroughly. 500 ml of the diluted ammonium sulfide solution was placed at the bottom of a desiccator chamber. The plated parts were placed, at least 3 inches above solution in the desiccator on a. ceramic plate, the top of the desiccators w s closed and the parts tested for one hour. Other contacts were plated with pure silver deposits and tested a a comparison. The pure silver deposits were a deep purple typically, indicative of sliver sulfide formation while the 5% antimony silver deposits were a very light yello color. The time in the chamber was increased to over- a few hour's. The pure silver deposit continued to darken while the 5% antimony silver deposit remained light yellow in color. This test result was deemed good enough to continue developing the process.

The ammonium sulfide chamber test was then conducted on 5% antimony-silver deposit sample made as described, in Example 5 coated, with polyphenol ether and perfiuropoiylether coatings. Similar .results to the .5% antimony- ilver samples without, coatings were obtained. Since the coating now seemed to pass both these tests, the wear and ammoniu sulfide tests were repeated after a IDOhr, / 120^'*C hake of the coated 5% antimony silver deposits. The ammonium sulfide tests also produced, little color change in the deposit after the bake for both coatings. How ver, only the perfl.uropolyet.her coating retained stable coefficient of friction values -at 0.3 or below.

EXAMPLE 7. CURRENT DEN SOY TESTIN G

The electroplating solution described, in. Exaxople 3 was now tested, at variable current densities to determine alloy variability. As the current density decreased_., the deposit became dull. At current densities below 75 asf, the percentage of antimony In the liver- ntimony alloy dropped below 1%_? as analy ed using wet chemistry methods, specifically conventional atomic Tl-A0.Q0.6P absorption spectroscopy. Next, the experiment was .conducted again., and -a- small amount of selenium was added to the bath as described In Example 5. The res ltin allo deposit was then alysed using the same methodology. The percentage of antimony at 75 asf was now In the 3,5% range and the deposit was full bright again. This was a surpris findin and it appears that the small amount f selenium added enhanced the co-deposition of antimony. Th deposit made in accord with Example 5 was then tested in the_: ammonium sulfide •chamber with the: same results. Other platin tests confirmed that the selenium added enhanced, the percentage of antimony in the deposit and expanded the plating bath's current density range, i.e., the range in which acceptable deposits could, he plated.

EXAMPLE 8. WEAR RESISTANCE TESTING

Fla eurih.ee and round contact surface electroplated -silver - antimony alloy deposited samples -were then tested for wear resistance- The wear- test was carried out unde a 200 gram load, for 50 back and. forth cycles simulating contact connector .insertions. The instrument used calculates the force as a .coefficient of friction betwee the two surfaces. Acceptable values for connectors under that gram.. load (200 grams) are values of coefficient of friction below 0.8. The S% antimony silver deposits made as described, in. Examples 3 and: 5 gave coefficient of friction values of 1.0 and greater. These results are illustrated in Figure 2,

To lower the coefficient of friction values to an Industry acceptable 0,8 COF or below, the 5% antimony silver deposits were immersed in separate solutions of (a) a polyphenol ether dissolved in. paraffin oil (TARMBAN CBGi, Technic Inc., Cranston, l¾l (ø} a perf luropolyether dissolved in a fluroalkane (Nye Lubricants, Fairhaven. MA) and (c) a fluorsxirfacant dissolved In. aqueous solutions. The samples were silver-antimony plated, dried,, and then Immersed in one of the coat solutions for 5 seconds, after which tile samples were warm air- dried. Next, each of these coated 5% antimony stiver deposits was tested tor wear resistance as described above. Because the fluorsurfaetant coated samples had coefficient of friction numbers thai were above 0,8, the fluorsu.facta.nt was eliminated from further study. The polyphenol ether and peril uropoiy!ether coated deposits produced stable coefficien of friction numbers near 0.2, well Tl-A0.Q0.6P below the 0.8 COF level d emed acceptable in. the industry. These results are Illustrated in Figure 3.

EXAMPLE I 0. MIXED FLOWING GAS TESTING

Sets of electrical contact material were plated with 5% antimony silver and coated With perfluropolyether in accord with th methods described above. These samples were tested using the Mixed Flowing Gas method according to indust y accepted spec EIA-364-6SB, Class 1.1 A for accelerated corrosion testing as described: earlier. This test is 20 days in dura ion under monitored atmospheric conditions and mimics accelerated testing In. ambient conditions.. The test use concentrated mixtures of common corrosive gases found, in the atmosphere. Samples are removed from the test chamber after each 5-day period and tested, Bach 5-day test period reflects 2 year of ambient atmospheric conditions. The contact sets were tested for wear and contact resistance as well as visual corrosion. Test results are shown in Figures 4-6. Figure 4 is a graphic representation of the MFC* test result fo the perfluropolyether coated 5% antimony silver sample deposits f l OO b.r/ 120^¾C Bake before Test), with Contact esistance plotted as function f Corrosion Resistance. No increase in contact resistance Is seen. In Figure 5, the wear test results are shown. o Increase in. wear over time is seen. In Figure 6 shows the ^'visual corrosion test results. No visual corrosion can be seen.

All patents, published patent applications, scientific and Industrial articles and documents referenced, in. this .specification are hereby Incorporated by reference for the substance of what they contain and disclose.

Claims

1. An aqueous electrolyte solution for use in electrodeposl ing a silver - antimony alloy at about 50-150 asf consisting essentiall of the following substances in substantially the proportions indicated:

120 g/1 Potassium Cyanide

15 g/1 Potassium Carbonate

35 g/1 Silver as Potassium Silve Cyanide

4 - 10 g/i Antimony as Antimony Tartrate

25 g/1 Roehelle Salts,

2. The electrolyte according to claim: 1 further comprising, between 0. 10 a d 2.00 ppra Selenium, as Potassium or Sodium Selenocyani.de,

3. An aqueou electrolyte solution for use in electrodepositmg a silver - antimony alloy at abou 50 -ISO asf consisting essentially of the following sub-stances in substantially the proportions irrdicat d;

120 g/1 Potassium. Cyanide

15 g/i Potassium Carbonate

35 g/1 Silver as Potassium. Silver Cyanide

4 - 1 g/i Antimony as Antimony Tartrate

25 g/i Roehelle Salts

0.10 - 2.00 pp Selenium as Potassium or Sodium Selenoeyaulde.

4. A iiie hod of preparing a bard silver alloy deposit on a conductive article comprising using the article as the cathode in an aqueous electrolyte solution according to claim 1 and electroplating the article at a< current density of between 50 and 150 asf

5. A method of preparing a hard silver alloy deposit on a conductive article comprising^' using the article as the cathode in an aqueous electrolyte solution according to claim. 2 and electroplating the article at a current density of between SO and 150 asf.

6. A method of preparing a hard silver allo deposit on a conductive article comprising using the article as the cathode in an aqueous electrolyte- solution Tl-A0.Q0.6P according to claim 3 and electroplating the article at a. current density of et een SO and 150 t

7. A method according to claim 4 further comprising the steps of drying the electroplated article and then immersing the article in a polyphenol ether or a perffuropolylether for an amoun of time sufficient to coat the article and allowing the article to dry ,

8. A method according to claim 5 further comprising the steps of drying the electroplated article and then immersing the article in a polyphenol ether or a perlliiroporylether tor an amount of time sufficien to coat the article and allowing the article to dry. A method, according to claim 6 further comprising the steps of drying the electroplated article and then inrrnereing the article in a polyphenol ether or a perfluropeiylethe for an amount of time sufficient to coat the article and allowing the article to dry,

10, An electrical connector comprising a silver ~ antimony alloy containing between 2 and 8 percent antimony made in accordance with the method of claim 4.

1 1 , An electrical connector comprising a. slive --- ntimony alloy containing between 2 and 8 percent antimony ma.de in accordance with the method of claim 5.

12, An electrical connector comprising a silver ~ antimony alloy containin between 2 and 8 percent antimony made in accordance with the method of claim 6.

10, An electrical connector comprising a silver— antimony alloy containing between. 2 and 8 percent antimony made m. accordance with the method of claim 7. Tl-A0.Q0.6P

11. An electrical connector comprising a silver --- antimony alley containin between 2 and 8 percent antimony made In accordance with the method of claim. 8.

12. An electrical connector comprising a silver - antaiiony alloy containing betwee 2 and 8 percent -antimony made in accordance with the method of claim 9.

13. A electrical connector comprising a body composed of hronse or copper, a barrier layer composed of nickel, and a contact layer covering the nickel layer, the contact layer consisting essentially of a silver ™ antimony alloy containin between 2 and B erce t, antimony,

.14, The electrical connector according to claim 13 further comprising a protective layer coverin the contact layer, the protective layer consisting essentiall of a polyphenol ether or a periluropolyiether,