Changes

For Pure Gold is besides Platinum the chemically most electrical contact applications gold alloys are usedstable of all precious metals. Depending on the alloying metal the melting In its pure form it is performed either under in not very suitable for use as a reducing atmosphere or contact material in a vacuum. The choice electromechanical devices because of alloying metals depends on the intended use of the resulting its tendency to stick and cold-weld at even low contact materialforces. The binary Au alloys with typically <10 wt% of other precious metals such as Pt, Pd, In addition it is not hard or Ag or non-precious metals like Ni, Co, strong enough to resist mechanical wear and Cu are the more commonly used ones ''exhibits high material losses under electrical arcing loads (Table 2.2<xr id="tab:Contact_and_Switching_Properties_of_Gold_and_Gold_Alloys"/>)''. On one hand these alloy additions improve the mechanical strength and electrical switching properties but on the other hand reduce the electrical conductivity and chemical corrosion resistance <!--(FigTab. 2.24) to varying degrees-->. This limits its use in form of thin electroplated or vacuum deposited layers.

[[FileFor most electrical contact applications, gold alloys are used. Depending on the alloying metal, the melting is performed either under a reducing atmosphere or in a vacuum. The choice of alloying metals depends on the intended use of the resulting contact material. The binary Au alloys with typically < 10 wt% of other precious metals such as Pt, Pd, Ag or non-precious metals like Ni, Co and Cu are the more commonly used ones (<xr id="tab:Physical Properties of Gold and Gold-Alloys"/>)<!--(Tab. 2.2)-->.jpg|right|thumb|Physical Properties of Gold On one hand these alloy additions improve the mechanical strength and electrical switching properties but on the other hand reduce the electrical conductivity and Goldchemical corrosion resistance (<xr id="fig:Influence_of_1_10_atomic_of_different"/>)<!--(Fig. 2.2)--Alloys]]> to varying degrees.

Under the aspect of reducing the gold content , ternary alloys with a gold contentof approximately 70 wt% and additions of Ag and Cu or Ag and Ni resp., forexample AuAg25Cu5 or AuAg20Cu10 are used , which exhibit for manyapplications good mechanical stability , while at the same time have sufficientresistance against the formation of corrosion layers ''(Table 2.3<xr id="tab:Mechanical Properties of Gold and Gold-Alloys"/>)''. Other ternaryalloys based on the AuAg system are AuAg26Ni3 and AuAg25Pt6. These alloysare mechanically similar to the AuAgCu alloys but have significantly higheroxidation resistance at elevated temperatures ''<!--(Table 2.43)''-->.

Caused by higher gold prices over the past years the development <figtable id="tab:Commonly Used Grades of alloys withGold">further reduced gold content had a high priority. The starting point has been theAuPd system which has continuous solubility <caption>'''Commonly Used Grades of the two componentsGold<!--(2. Besides1)-->'''</caption>the binary alloy of AuPd40 and the ternary one AuPd35Ag9 other multiplecomponent alloys were developed. These alloys typically have < 50 wt% Au andoften can be solution hardened in order to obtain even higher hardness andtensile strength. They are mostly used in sliding contact applications.table class="twocolortable">

Gold alloys are used in the form of welded wire or profile <tr><th><p class="s11">Designation</p></th><th><p class="s11">Composition Au</p><p class="s11">(also called weldtapesmin. content)</p></th><th><p class="s11">Impurites ppm</p></th><th><p class="s12">Remarks on forms and application</p></th></tr><tr><td><p class="s11">Electronic Gold</p><p class="s11">Gold</p></td><td><p class="s11">99.999</p></td><td><p class="s11">Cu &lt; 3</p><p class="s11">Ag &lt; 3</p><p class="s11">Ca &lt; 1</p><p class="s11">Mg &lt;1</p><p class="s11">Fe &lt; 1</p></td><td><p class="s12">Wires,segmentsstrips, contact rivetsalloying metal for semiconductors, and stampings produced from clad stripmaterials electronic components</p></td></tr><tr><td><p class="s11">Pure Gold</p></td><td><p class="s11">99. The selection of the bonding process is based on the cost 995</p></td><td><p class="s11">Cu &lt; 10</p><p class="s11">Ag &lt; 15</p><p class="s11">Ca &lt; 20</p><p class="s11">Mg &lt; 10</p><p class="s11">Fe &lt; 3</p><p class="s11">Si &lt; 10</p><p class="s11">Pb &lt; 20</p></td><td><p class="s12">Granulate for thehigh purity alloys, strips, tubing, profiles</p></td></tr><tr><td><p class="s11">Ingot Grade-Gold</p></td><td><p class="s11">99.95</p></td><td><p class="s11">Cu &lt; 100</p><p class="s11">Ag &lt; 150</p><p class="s11">Ca &lt; 50</p><p class="s11">Mg &lt; 50</p><p class="s11">Fe &lt; 30</p><p class="s11">Si &lt; 10</p></td><td><p class="s12">Alloys, commonly used grade</p></td></tr></table></figtable>joining process, and most importantly on the economical aspect of using the<br/>least possible amount of the expensive precious metal component.<br/>

Besides being used as switching contacts in relays <figtable id="tab:Physical Properties of Gold and pushbuttons, goldGold-Alloys">alloys are also applied in the design <caption>'''Physical Properties of connectors as well as sliding contacts forpotentiometers, sensors, slip rings, Gold and brushes in miniature DC motors'Gold-Alloys'(Table 2.5)''.</caption>

{| class="twocolortable" style="text-align: left; font-size: 12px"|-!Material!Gold<br/>Content<br/>[wt.%]!Density<br/>[g/cm³]!Melting Point<br/>or Range<br/>[°C]!Electrical<br/>Resistivity<br/>[µΩ*cm]!Electrical<br/>Conductivity<br/>[MS/m]!Thermal<br/>Conductivity<br/>[W/(m*K)]!Temp. Coeff. of<br/>the electr. Resistance<br/>[File:Mechanical Properties 10<sup>-3<sup/>/K]!Modulus of Gold and Gold Alloys<br/>Elasticity<br/>[GPa]|-|Au (99,95)| >99,95|19,3|1064|2,32|43|317|4,0|79|-|AuAg8|92|18,1|1058|6,13|16,3|147|1,25|82|-|AuAg20|80|16,4|1035 - 1045|10,0|10|75|0,86|89|-|AuNi5|95|18,3|995 - 1018|13,5|7,4|53|0,71|83|-|AuCo5|95|18,2|1010 - 1015|55,6|1,8||0,68|88|-|AuCo5 (het.jpg)|95|18,2|1010 - 1015|5,99|16,7||||-|AuAg25Cu5|70|15,2|950 - 980|12,2|8,2||0,75|89|-|AuAg20C10|70|15,1|right865 - 895|thumb13,3|Mechanical Properties of Gold and Gold Alloys]]7,5|66|0,52|87|-|AuAg26Ni3|71|15,4|990 - 1020|11,0|9,1|59|0,88|114|-|AuPt10|90|19,5|1150 - 1190|12,5|8,0|54|||-|AuAg25Pt6|69|16,1|1060|15,9|6,3|46|0,54|93|-|AuCu14Pt9Ag4|73|16,0|955|14,3 - 25|4 - 7||||-|}</figtable>

Table <div class="multiple-images"><figure id="fig:Influence_of_1_10_atomic_of_different">[[File:Influence of 1-10 atomic of different.jpg|left|thumb|<caption>Fig 2.3: Mechanical Properties 2 Influence of Gold and Gold1-Alloys10 atomic% of different alloying metals on the electrical resistivity of gold (according to J. O. Linde)</caption>]]</figure></div><div class="clear"></div>

Table <figtable id="tab:Mechanical Properties of Gold and Gold-Alloys"><caption>'''<!--Tab.2.13: Commonly Used Grades -->Mechanical Properties of Goldand Gold-Alloys'''</caption>{| class="twocolortable" style="text-align: left; font-size: 12px"|-!Material !Hardness Condition!Tensile Strength Rm [MPa] min.!Elongation A₁₀ [%] min.!Vickers Hardness HV|-|Au|R 140<br />R 170<br />R 200<br />R 240|140<br />170<br />200<br />240|30<br />3<br />2<br />1|20<br />50<br />60<br />70|- |AuAg20|R 190<br />R 250<br />R 320<br />R 390|190<br />250<br />320<br />390|25<br />2<br />1<br />1|38<br />70<br />95<br />115|-|AuAg30|R 220<br />R 260<br />R 320<br />R 380|220<br />260<br />320<br />380|25<br />3<br />1<br />1|45<br />75<br />95<br />110|-|AuAg25Cu5|R 400<br />R 470<br />R 570<br />R 700|400<br />470<br />570<br />700|25<br />4<br />2<br />2|90<br />120<br />160<br />185|-|AuAg20Cu10|R 480<br />R 560<br />R 720<br />R 820|480<br />560<br />720<br />820|20<br />3<br />1<br />1|125<br />145<br />190<br />230|-|AuAg26Ni3|R 350<br />R 420<br />R 500<br />R 570|350<br />420<br />500<br />570|20<br />2<br />1<br />1|85<br />110<br />135<br />155|-|AuAg25Pt6|R 280<br />R 330<br />R 410<br />R 480|280<br />330<br />410<br />480|18<br />2<br />1<br />1|60<br />90<br />105<br />125|-|AuCo5|R 340<br />R 390<br />R 450<br />R 530|340<br />390<br />450<br />530|10<br />2<br />1<br />1|95<br />105<br />120<br />150|-|AuCo5 prec.hardened|heterogeneous|360|3|110-130|-|AuNi5|R 380<br />R 450<br />R 560<br />R 640|380<br />450<br />560<br />640|25<br />3<br />2<br />1|115<br />135<br />160<br />190|-|AuPt10|R 260<br />R 310<br />R 370<br />R 410|260<br />310<br />370<br />410|20<br />2<br />1<br />1|80<br />90<br />100<br />105|-|AuCu14Pt9Ag4|R 620<br />R 700<br />R 850<br />R 950<br />prec.hardened|620<br />700<br />850<br />950<br />900|20<br />3<br />2<br />1<br />3|190<br />225<br />260<br />270<br />280|}</figtable>

<figtable id="tab:Contact_and_Switching_Properties_of_Gold_and_Gold_Alloys"><caption>'''<!--Table 2.24: Physical -->Contact and Switching Properties of Gold and GoldAlloys'''</caption><table class="twocolortable"> <tr><th><p class="s11">Material</p></th><th><p class="s12">Properties<th colspan="2"></p></th></tr><tr><td><p class="s11">Au</p></td><td><p class="s12">Highest corrosion resistance, low</p><p class="s12">hardness</p></td><td><p class="s12">High electr. conductivity,</p><p class="s12">strong tendency to cold welding</p></td></tr><tr><td><p class="s11">AuAg8</p></td><td><p class="s12">High corrosion resistance, low thermo</p><p class="s12">e.m.f.</p></td><td><p class="s12">Low contact resistance</p></td></tr><tr><td><p class="s11">AuPt10</p><p class="s11">AuPd5</p></td><td><p class="s12">Very high corrosion resistance</p></td><td><p class="s12">High hardness</p></td></tr><tr><td><p class="s11">AuAg10 -Alloys30</p></td><td><p class="s12">Mostly corrosion resistant</p></td><td><p class="s12">Higher hardness</p></td></tr><tr><td><p class="s11">AuNi5</p><p class="s11">AuCo5</p></td><td><p class="s12">High corrosion resistance, low</p><p class="s12">tendency to material transfer</p></td><td><p class="s12">High hardness</p></td></tr><tr><td><p class="s11">AuAg25Pt6</p></td><td><p class="s12">High corrosion resistance, low contact resistance</p></td><td><p class="s12">High hardness</p></td></tr><tr><td><p class="s11">AuAg26Ni3</p><p class="s11">AuAg25Cu5</p><p class="s11">AuAg20Cu10</p></td><td><p class="s12">Limited corrosion resistance</p></td><td><p class="s12">High hardness</p></td></tr><tr><td><p class="s11">AuPd40</p><p class="s11">AuPd35Ag10</p><p class="s11">AuCu14Pt9Ag4</p></td><td><p class="s12">High corrosion resistance</p></td><td><p class="s12">High hardness and mechanical</p><p class="s12">wear resistance</p></td></tr></table></figtable>

[[File:Influence Caused by higher gold prices over the past years, the development of 1-10 atomic alloys with further reduced gold content had a high priority. The starting point has been the AuPd system, which has continuous solubility of differentthe two components.jpg|right|thumb|Influence Besides the binary alloy of 1-10 atomicAuPd40 and the ternary one AuPd35Ag9, other multiple component alloys were developed. These alloys typically have < 50 wt% of different alloying metals on the electrical resistivity of gold (according Au and often can be solution hardened in order to Jobtain even higher hardness and tensile strength. OThey are mostly used in sliding contact applications. Linde)]]

Fig. 2Gold alloys are used in the form of welded wire or profile (also called weldtapes), segments, contact rivets and stampings produced from clad stripmaterials.2:Influence The selection of 1-10 atomic% the bonding process is based on the cost for the joining process and most importantly on the economical aspect of differentalloying metals on using the electrical resistivity least possible amount of gold(according to Jthe expensive precious metal component. O. Linde)

[[FileBesides being used as switching contacts in relays and pushbuttons, gold alloys are also applied in the design of connectors as well as sliding contacts for potentiometers, sensors, slip rings and brushes in miniature DC motors (<xr id="tab:Phase diagram Application Examples and Forms of goldplatinumGold and Gold Alloys"/>)<!--(Table 2.5)-->.jpg|right|thumb|Phase diagram of goldplatinum]]

Fig. <figtable id="tab:Application Examples and Forms of Gold and Gold Alloys"><caption>'''<!--Table 2.35:Phase diagram-->Application Examples and Forms of goldplatinumGold and Gold Alloys'''</caption>

[[File:Phase diagram <table class="twocolortable"><tr><th><p class="s11">Material</p></th><th><p class="s12">Application Examples</p></th><th><p class="s12">Form of goldApplication</p></th></tr><tr><td><p class="s11">Pure Gold</p><p class="s11">(electroplated)</p></td><td><p class="s12">Corrosion protection layer for contact parts, stationary contacts, bonding surfaces</p></td><td><p class="s12">Electroplated coatings, bond surface layers</p></td></tr><tr><td><p class="s11">Hard Gold</p><p class="s11">(sputtered)</p></td><td><p class="s12">Contact parts for connectors and switches, sliding contact tracks, bonding surfaces</p></td><td><p class="s12">Electroplated coatings on contact rivets and stamped parts</p></td></tr><tr><td><p class="s11">Hard Gold</p><p class="s11">(sputtered)</p></td><td><p class="s12">Contacts in switches and relays for low loads, electronic signal relays</p></td><td><p class="s12">Contact surface layer on miniature</p><p class="s12">profiles (weld tapes)</p></td></tr><tr><td><p class="s11">AuAg8</p></td><td><p class="s12">Dry circuit switching contacts, electronic</p><p class="s12">signal relays</p></td><td><p class="s12">Contact rivets, welded contact</p><p class="s12">parts</p></td></tr><tr><td><p class="s11">AuAg20</p></td><td><p class="s12">Switching contacts for low loads, electronic</p><p class="s12">signal relays</p></td><td><p class="s12">Contact rivets, welded contact</p><p class="s12">parts</p></td></tr><tr><td><p class="s11">AuAg25Cu5</p><p class="s11">AuAg25Cu10</p><p class="s11">AuAg26Ni3</p></td><td><p class="s12">Contact parts for connectors, switches and relays</p></td><td><p class="s12">Claddings on Cu alloys, contact rivets, contact layer on micro profiles (weld tapes)</p></td></tr><tr><td><p class="s11">AuNi5</p><p class="s11">AuCo5 (heterogen)</p></td><td><p class="s12">Contacts in switches and relays for low and medium loads, material transfer resistant contacts</p></td><td><p class="s12">Contact rivets, welded contact parts, contact layer on miniature profiles (weld tapes)</p></td></tr><tr><td><p class="s11">AuPt10</p><p class="s11">AuAg25Pt6</p></td><td><p class="s12">Contacts for highest chemical corrosion resistance in switches and relays</p></td><td><p class="s12">Contact rivets, contact layer on micro profiles (weld tapes)</p></td></tr><tr><td><p class="s11">AuCu14Pt9Ag4</p></td><td><p class="s12">Sliding contacts for measurement data transfer</p></td><td><p class="s12">Wire-silver.jpg|right|thumb|Phase diagram of gold-silver]]formed parts</p></td></tr></table></figtable>

Fig. 2.5<div class="multiple-images"><figure id="fig:Phase diagram of goldplatinum">[[File:Phase diagramof goldplatinum.jpg|left|thumb|<caption>Phase diagram of goldplatinum</caption>]]of gold-copper</figure>

Fig<figure id="fig:Phase diagram of gold-silver">[[File:Phase diagram of gold-silver. 2.6: jpg|left|thumb|<caption>Phase diagram of gold-nickelsilver</caption>]]</figure>

Fig<figure id="fig:Phase diagram of gold-copper">[[File:Phase diagram of gold-copper. 2.7: jpg|left|thumb|<caption>Phase diagram of gold-cobaltcopper</caption>]]</figure>

Fig. 2.8<figure id="fig:Phase diagram of gold-nickel">Strain hardening[[File:Phase diagram of gold-nickel.jpg|left|thumb|<caption>Phase diagram of gold-nickel</caption>]]of Au by cold working</figure>

Fig. 2.9<figure id="fig:Phase diagram of gold-cobalt">Softening [[File:Phase diagram of Au after annealingfor 0gold-cobalt.5 hrs after 80%jpg|left|thumb|<caption>Phase diagram of gold-cobalt</caption>]]cold working</figure>

Fig. 2.10<figure id="fig:Strain hardening of Au by cold working">[[File:Strain hardening ofAuPt10 Au by cold working.jpg|left|thumb|<caption>Strain hardening of Au by cold working</caption>]]</figure>

Fig<figure id="fig:Softening of Au after annealing for 0.5 hrs">[[File:Softening of Au after annealing for 0. 25 hrs.11:Strain hardeningjpg|left|thumb|<caption>Softening of AuAg20 by Au after annealing for 0.5 hrs after 80% cold working</caption>]]</figure>

Fig. 2.12<figure id="fig:Strain hardening of AuPt10 by cold working">[[File:Strain hardening ofAuAg30 AuPt10 by cold working.jpg|left|thumb|<caption>Strain hardening of AuPt10 by cold working</caption>]]</figure>

Fig. 2.13<figure id="fig:Strain hardening of AuAg20 by cold working">[[File:Strain hardening of AuNi5AuAg20 by cold working.jpg|left|thumb|<caption>Strain hardening of AuAg20 by cold working</caption>]]</figure>

Fig. 2.14<figure id="fig:Strain hardening of AuAg30 by cold working">Softening[[File:Strain hardening of AuNi5 after annealingfor 0AuAg30 by cold working.5 hrs after 80%jpg|left|thumb|<caption>Strain hardening of AuAg30 by cold working</caption>]]</figure>

Fig. 2.15<figure id="fig:Strain hardening of AuNi5 by cold working">[[File:Strain hardening of AuNi5 by cold working.jpg|left|thumb|<caption>Strain hardeningof AuCo5 AuNi5 by cold working</caption>]]</figure>

Fig<figure id="fig:Softening of AuNi5 after annealing for 0.5 hrs">[[File:Softening of AuNi5 after annealing for 0. 25 hrs.16:Precipitation hardening jpg|left|thumb|<caption>Softening ofAuNi5 after annealing for 0.5 hrs after 80% cold working</caption>]]AuCo5 at 400°C hardeningtemperature</figure>

Fig. 2.17<figure id="fig:Strain hardening of AuCo5 by cold working">[[File:Strain hardening of AuCo5 by cold working.jpg|left|thumb|<caption>Strain hardeningof AuAg25Pt6 AuCo5 by cold working</caption>]]</figure>

Fig. 2.18<figure id="fig:Precipitation hardening of AuCo5 at">Strain [[File:Precipitation hardeningof AuCo5 at.jpg|left|thumb|<caption>Precipitation hardening of AuCo5 at 400°C hardening temperature</caption>]]of AuAg26Ni3 by cold working</figure>

Fig. 2.19<figure id="fig:Strain hardening of AuAg25Pt6 by cold working">Softening[[File:Strain hardening of AuAg26Ni3 afterannealing for 0AuAg25Pt6 by cold working.5 hrsafter 80% jpg|left|thumb|<caption>Strain hardening of AuAg25Pt6 by coldworking</caption>]]working</figure>

Fig. 2.20<figure id="fig:Strain hardening of AuAg26Ni3 by cold working">[[File:Strain hardening ofAuAg25Cu5AuAg26Ni3 by cold working.jpg|left|thumb|<caption>Strain hardening of AuAg26Ni3 by cold working</caption>]]</figure>

Fig<figure id="fig:Softening of AuAg26Ni3 after annealing for 0.5-hrs">[[File:Softening of AuAg26Ni3 after annealing for 0. 25-hrs.21:Strain hardening jpg|left|thumb|<caption>Softening ofAuAg20Cu10by AuAg26Ni3 after annealing for 0.5 hrs after 80% cold working</caption>]]</figure>

Fig. 2.22<figure id="fig:Strain hardening of AuAg25Cu5 by cold working">Softening[[File:Strain hardening of AuAg20Cu10 afterannealing for 0AuAg25Cu5 by cold working.5 hrsafter 80% jpg|left|thumb|<caption>Strain hardening of AuAg25Cu5 by cold working</caption>]]</figure>

Fig. 2.23<figure id="fig:Strain hardening of AuAg20Cu10 by cold working">[[File:Strain hardening ofAuCu14Pt9Ag4AuAg20Cu10 by cold working.jpg|left|thumb|<caption>Strain hardening of AuAg20Cu10 by cold working</caption>]]</figure>

Fig<figure id="fig:Softening of AuAg20Cu10 after annealing for 0.5 hrs">[[File:Softening of AuAg20Cu10 after annealing for 0. 25 hrs.24:Precipitationhardening jpg|left|thumb|<caption>Softening ofAuCu14Pt9Ag4at differenthardeningtemperaturesAuAg20Cu10 after annealing for 0.5 hrs after 5080%cold working</caption>]]</figure>

Table 2<figure id="fig:Strain hardening of AuCu14Pt9Ag4 by cold working">[[File:Strain hardening of AuCu14Pt9Ag4 by cold working.4: Contact and Switching Properties jpg|left|thumb|<caption>Strain hardening of Gold and Gold AlloysAuCu14Pt9Ag4 by cold working</caption>]]</figure>

Table 2<figure id="fig:Precipitation hardening of AuCu14Pt9Ag4">[[File:Precipitation hardening of AuCu14Pt9Ag4.5: Application Examples and Forms jpg|left|thumb|<caption>Precipitation hardening of Gold and Gold AlloysAuCu14Pt9Ag4 at different hardening temperatures after 50% cold working</caption>]]</figure></div><div class="clear"></div>