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 materials losses under electrical arcing loads <xr id="tab:tab2.2Contact_and_Switching_Properties_of_Gold_and_Gold_Alloys"/> ''<!--(Table Tab. 2.24)''. 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 <xr id="fig:fig2.2"/-->''(Fig. 2.2)'' to varying degreesThis limits its use in form of thin electroplated or vacuum deposited layers.

Under the aspect of reducing the gold content ternary alloys with a gold content of approximately 70 wt% and additions of Ag and Cu or Ag and Ni resp., for example AuAg25Cu5 or AuAg20Cu10 are used which exhibit for many applications good mechanical stability while at the same time have sufficientresistance against the formation of corrosion layers <xr id="tab:tab2Mechanical Properties of Gold and Gold-Alloys"/><!--(Table 2.3)-->. <figtable id="/tab:Commonly Used Grades of Gold"><caption>'''Commonly Used Grades of Gold<!--(Table 2.31)-->'''</caption><table class="twocolortable">  <tr><th><p class="s11">Designation</p></th><th><p class="s11">Composition Au</p><p class="s11">(min. 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 Glod</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, strips, alloying metal for semiconductors, electronic components</p></td></tr><tr><td><p class="s11">Pure Gold</p></td><td><p class="s11">99.995</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 high 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>

<figtable id="tab:tab2.2Physical_Properties_of_Gold_and_Gold_Alloys">[[File:Physical Properties of Gold and Gold-Alloys.jpg|left|thumb| <caption>Tab 2.2 Physical Properties of Gold and Gold-Alloys</caption>]]

<figure id="fig:fig2.2Influence_of_1_10_atomic_of_different">[[File:Influence of 1-10 atomic of different.jpg|left|thumb|<caption>Fig 2.2 Influence of 1-10 atomic% of different alloying metals on the electrical resistivity of gold (according to J. O. Linde)</caption>]]

  <figtable id="tab:Mechanical Properties of Gold and Gold-Alloys"><caption>'''<!--Tab.2.3: -->Mechanical Properties of Gold and Gold-Alloys'''<figtable id="tab:tab2.3"/caption>

Other ternary alloys based on the AuAg system are AuAg26Ni3 and AuAg25Pt6. These alloys are mechanically similar to the AuAgCu alloys but have significantly higher oxidation resistance at elevated temperatures <xr id="tab:Contact_and_Switching_Properties_of_Gold_and_Gold_Alloys"/><!--(Table 2.4)-->. <figtable id="tab:Contact_and_Switching_Properties_of_Gold_and_Gold_Alloys"><caption>'''<!--Table 2.4: -->Contact and Switching Properties of Gold and Gold Alloys'''</caption><table border="1" cellspacing="0" styleclass="border-collapse:collapsetwocolortable"><tr><tdth><p class="s11">Material</p></tdth><tdth><p class="s12">Properties<th colspan="2"></p></tdth></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 - 30</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> 

materials. The selection of the bonding process is based on the cost for the joining process, and most importantly on the economical aspect of using theleast possible amount of the expensive precious metal component.

Besides 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:Application Examples and Forms of Gold and Gold Alloys"/><!--(Table 2.5)''-->.

'''Table 2.5<figtable id="tab: Application Examples and Forms of Gold and Gold Alloys"><caption>'''<table border="1" cellspacing="0" style="border!--collapseTable 2.5:collapse"><tr><td><p class="s11">Material</p></td><td><p class="s12"-->Application Examples</p></td><td><p class="s12">Form and Forms of Application</p></td></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 GoldAlloys'''</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-formed parts</p></td></tr></tablecaption>

'''Table 2.1: Commonly Used Grades of Gold'''<table class="twocolortable"><table bordertr><th><p class="1s11" cellspacing>Material</p></th><th><p class="0s12" style>Application Examples</p></th><th><p class="border-collapse:collapses12">Form of Application</p></th></tr><tr><td><p class="s11">DesignationPure 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">Composition AuHard Gold</p><p class="s11">(min. contentsputtered)</p></td><td><p class="s11s12">Impurites ppmContact parts for connectors and switches, sliding contact tracks, bonding surfaces</p></td><td><p class="s12">Remarks Electroplated coatings on forms contact rivets and applicationstamped parts</p></td></tr><tr><td><p class="s11">Electronic GlodHard Gold</p><p class="s11">Gold(sputtered)</p></td><td><p class="s11s12">99.999Contacts in switches and relays for low loads, electronic signal relays</p></td><td><p class="s11s12">Cu &lt; 3Contact surface layer on miniature</p><p class="s11s12">Ag &lt; 3profiles (weld tapes)</p></td></tr><tr><td><p class="s11">Ca &lt; 1AuAg8</p></td><td><p class="s11s12">Mg &lt;1Dry circuit switching contacts, electronic</p><p class="s11s12">Fe &lt; 1signal relays</p></td><td><p class="s12">WiresContact rivets, strips, alloying metal for semiconductors, electronic componentswelded contact</p><p class="s12">parts</p></td></tr><tr><td><p class="s11">Pure GoldAuAg20</p></td><td><p class="s11s12">Switching contacts for low loads, electronic</p><p class="s12">99.995signal relays</p></td><td><p class="s11s12">Cu &lt; 10Contact rivets, welded contact</p><p class="s11s12">Ag &lt; 15parts</p><p class="s11"/td>Ca &lt; 20</ptr><tr><td><p class="s11">Mg &lt; 10AuAg25Cu5</p><p class="s11">Fe &lt; 3AuAg25Cu10</p><p class="s11">Si &lt; 10AuAg26Ni3</p></td><td><p class="s11s12">Pb &lt; 20Contact parts for connectors, switches and relays</p></td><td><p class="s12">Granulate for high purity Claddings on Cu alloys, strips, tubingcontact rivets, contact layer on micro profiles(weld tapes)</p></td></tr><tr><td><p class="s11">Ingot Grade-GoldAuNi5</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="s11s12">99.95Contact rivets, welded contact parts, contact layer on miniature profiles (weld tapes)</p></td></tr><tr><td><p class="s11">Cu &lt; 100AuPt10</p><p class="s11">Ag &lt; 150AuAg25Pt6</p></td><td><p class="s11s12">Ca &lt; 50Contacts for highest chemical corrosion resistance in switches and relays</p></td><td><p class="s11s12">Mg &lt; 50Contact rivets, contact layer on micro profiles (weld tapes)</p></td></tr><tr><td><p class="s11">Fe &lt; 30AuCu14Pt9Ag4</p></td><td><p class="s11s12">Si &lt; 10Sliding contacts for measurement data transfer</p></td><td><p class="s12">Alloys, commonly used gradeWire-formed parts</p></td></tr></table></figtable>

 <xr id="fig:fig2.24Precipitation hardening of AuCu14Pt9Ag4"/> Fig. 2.24: Precipitation hardening of AuCu14Pt9Ag4 at different hardening temperatures after 50% cold working

<figure id="fig:fig2.3Phase diagram of goldplatinum">[[File:Phase diagram of goldplatinum.jpg|rightleft|thumb|<caption>Phase diagram of goldplatinum</caption>]]

<figure id="fig:fig2.4Phase diagram of gold-silver">[[File:Phase diagram of gold-silver.jpg|rightleft|thumb|<caption>Phase diagram of gold-silver</caption>]]

<figure id="fig:fig2.5Phase diagram of gold-copper">[[File:Phase diagram of gold-copper.jpg|rightleft|thumb|<caption>Phase diagram of gold-copper</caption>]]

<figure id="fig:fig2.6Phase diagram of gold-nickel">[[File:Phase diagram of gold-nickel.jpg|rightleft|thumb|<caption>Phase diagram of gold-nickel</caption>]]

<figure id="fig:fig2.7Phase diagram of gold-cobalt">[[File:Phase diagram of gold-cobalt.jpg|rightleft|thumb|<caption>Phase diagram of gold-cobalt</caption>]]

<figure id="fig:fig2.8Strain hardening of Au by cold working">[[File:Strain hardening of Au by cold working.jpg|rightleft|thumb|<caption>Strain hardening of Au by cold working</caption>]]

<figure id="fig:fig2Softening of Au after annealing for 0.95 hrs">[[File:Softening of Au after annealing for 0.5 hrs.jpg|rightleft|thumb|<caption>Softening of Au after annealing for 0.5 hrs after 80% cold working</caption>]]

<figure id="fig:fig2.10Strain hardening of AuPt10 by cold working">[[File:Strain hardening of AuPt10 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuPt10 by cold working</caption>]]

<figure id="fig:fig2.11Strain hardening of AuAg20 by cold working">[[File:Strain hardening of AuAg20 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg20 by cold working</caption>]]

<figure id="fig:fig2.12Strain hardening of AuAg30 by cold working">[[File:Strain hardening of AuAg30 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg30 by cold working</caption>]]

<figure id="fig:fig2.13Strain hardening of AuNi5 by cold working">[[File:Strain hardening of AuNi5 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuNi5 by cold working</caption>]]

<figure id="fig:fig2Softening of AuNi5 after annealing for 0.145 hrs">[[File:Softening of AuNi5 after annealing for 0.5 hrs.jpg|rightleft|thumb|<caption>Softening of AuNi5 after annealing for 0.5 hrs after 80% cold working</caption>]]

<figure id="fig:fig2.15Strain hardening of AuCo5 by cold working">[[File:Strain hardening of AuCo5 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuCo5 by cold working</caption>]]

<figure id="fig:fig2.16Precipitation hardening of AuCo5 at">[[File:Precipitation hardening of AuCo5 at.jpg|rightleft|thumb|<caption>Precipitation hardening of AuCo5 at 400°C hardening temperature</caption>]]

<figure id="fig:fig2.17Strain hardening of AuAg25Pt6 by cold working">[[File:Strain hardening of AuAg25Pt6 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg25Pt6 by cold working</caption>]]

<figure id="fig:fig2.18Strain hardening of AuAg26Ni3 by cold working">[[File:Strain hardening of AuAg26Ni3 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg26Ni3 by cold working</caption>]]

<figure id="fig:fig2Softening of AuAg26Ni3 after annealing for 0.195-hrs">[[File:Softening of AuAg26Ni3 after annealing for 0.5-hrs.jpg|rightleft|thumb|<caption>Softening of AuAg26Ni3 after annealing for 0.5 hrs after 80% cold working</caption>]]

<figure id="fig:fig2.20Strain hardening of AuAg25Cu5 by cold working">[[File:Strain hardening of AuAg25Cu5 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg25Cu5 by cold working</caption>]]

<figure id="fig:fig2.21Strain hardening of AuAg20Cu10 by cold working">[[File:Strain hardening of AuAg20Cu10 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg20Cu10 by cold working</caption>]]

<figure id="fig:fig2Softening of AuAg20Cu10 after annealing for 0.225 hrs">[[File:Softening of AuAg20Cu10 after annealing for 0.5 hrs.jpg|rightleft|thumb|<caption>Softening of AuAg20Cu10 after annealing for 0.5 hrs after 80% cold working</caption>]]

<figure id="fig:fig2.23Strain hardening of AuCu14Pt9Ag4 by cold working">[[File:Strain hardening of AuCu14Pt9Ag4 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuCu14Pt9Ag4 by cold working</caption>]]

<figure id="fig:fig2.24Precipitation hardening of AuCu14Pt9Ag4">[[File:Precipitation hardening of AuCu14Pt9Ag4.jpg|rightleft|thumb|<caption>Precipitation hardening of AuCu14Pt9Ag4 at different hardening temperatures after 50% cold working</caption>]]