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 (<xr id="tab:tab2.2Contact_and_Switching_Properties_of_Gold_and_Gold_Alloys"/> ''(Table 2.2)''. 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"/>''!--(FigTab. 2.24)'' to varying degrees-->. This limits its use in form of thin electroplated or vacuum deposited layers.

For 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 (<figtable xr id="tab:tab2Physical Properties of Gold and Gold-Alloys"/>)<!--(Tab. 2.2)-->.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:Influence_of_1_10_atomic_of_different"/>)<!--(Fig. 2.2)--> to varying degrees.[[FileUnder 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 sufficient resistance against the formation of corrosion layers (<xr id="tab:Physical Mechanical Properties of Gold and Gold-Alloys"/>)<!--(Table 2.jpg|right|thumb| Tab 23)-->.2 Physical Properties  <figtable id="tab:Commonly Used Grades of Gold"><caption>'''Commonly Used Grades of Gold <!--(2.1)-->'''</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 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, 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>

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

Under the aspect <figtable id="tab:Physical Properties of reducing the gold content ternary alloys with a gold content of approximately 70 wt% Gold and additions Gold-Alloys"><caption>'''Physical Properties of Ag Gold 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 'Gold-Alloys'(Table 2.3)''.</caption>

'''Tab<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-Alloys'''10 atomic% of different alloying metals on the electrical resistivity of gold (according to J. O. Linde)</caption>]]</figure></div><div class="clear"></div>

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" cellspacingclass="0" style="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>Caused by higher gold prices over the past years the development of alloys with further reduced gold content had a high priority. The starting point has been the AuPd system which has continuous solubility of the two components. Besides the binary alloy of AuPd40 and the ternary one AuPd35Ag9 other multiple component alloys were developed. These alloys typically have < 50 wt% Au and often can be solution hardened in order to obtain even higher hardness and tensile strength. They are mostly used in sliding contact applications./figtable>

Gold alloys are used in Caused by higher gold prices over the past years, the form development of welded wire or profile (also called weldtapes), segments, contact rivets, and stampings produced from clad stripmaterialsalloys with further reduced gold content had a high priority. The selection of the bonding process is based on the cost for starting point has been the joining processAuPd system, and most importantly on which has continuous solubility of the economical aspect of using two components. Besides theleast possible amount binary alloy of AuPd40 and the expensive precious metal ternary one AuPd35Ag9, other multiple componentalloys were developed. These alloys typically have < 50 wt% Au and often can be solution hardened in order to obtain even higher hardness and tensile strength. They are mostly used in sliding contact applications.

Besides being used as switching contacts in relays and pushbuttons, gold Gold alloys are also applied used in the design form of connectors as well as sliding contacts for potentiometers, sensorswelded wire or profile (also called weldtapes), slip ringssegments, contact rivets and brushes in miniature DC motors ''(Table 2stampings produced from clad stripmaterials.5)''The selection of the bonding process is based on the cost for the joining process and most importantly on the economical aspect of using the least possible amount of the expensive precious metal component.

'''Table 2.5: Application Examples Besides being used as switching contacts in relays and Forms pushbuttons, gold alloys are also applied in the design of Gold and Gold Alloys'''<table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s11">Material</p></td><td><p class="s12">Application Examples</p></td><td><p class="s12">Form 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 connectors as well as sliding 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 switchespotentiometers, sliding contact trackssensors, bonding surfaces</p></td><td><p class="s12">Electroplated coatings on contact rivets slip rings 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 brushes 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 DC motors (weld tapes)</p></td></tr><tr><td><p classxr id="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 tab:Application Examples and Forms of Gold 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=Gold Alloys"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 tapesTable 2.5)</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></table->.

'''Table 2.1: Commonly Used Grades of Gold'''<table border="1" cellspacingfigtable id="0" style="border-collapsetab:collapse"><tr><td><p class="s11">Designation</p></td><td><p class="s11">Composition Au</p><p class="s11">(min. content)</p></td><td><p class="s11">Impurites ppm</p></td><td><p class="s12">Remarks on forms Application Examples and application</p></td></tr><tr><td><p class="s11">Electronic Glod</p><p class="s11">Forms of 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 and Gold</p></td><td><p class="s11Alloys">99.995</pcaption>'''</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">99Table 2.95</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"5:-->Application Examples and Forms of Gold and Gold Alloys, commonly used grade</p></td></tr>'''</tablecaption>

Fig. 2.3: 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 goldplatinumApplication</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-formed parts</p></td></tr></table>[[File:Phase diagram of goldplatinum.jpg|right|thumb|Phase diagram of goldplatinum]]</figtable>

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

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

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

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

Fig. 2.9<figure id="fig: Softening Phase diagram of Au after annealing for 0.5 hrs after 80% cold workinggold-cobalt">[[File:Softening Phase diagram of Au after annealing for 0.5 hrsgold-cobalt.jpg|rightleft|thumb|Softening <caption>Phase diagram of Au after annealing for 0.5 hrs after 80% cold workinggold-cobalt</caption>]]</figure>

Fig. 2.10<figure id="fig: Strain hardening of AuPt10 Au by cold working">[[File:Strain hardening of AuPt10 Au by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuPt10 Au by cold working</caption>]]</figure>

Fig. 2.11<figure id="fig: Strain hardening Softening of AuAg20 by cold workingAu after annealing for 0.5 hrs">[[File:Strain hardening Softening of AuAg20 by cold workingAu after annealing for 0.5 hrs.jpg|rightleft|thumb|Strain hardening <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 AuAg30 AuPt10 by cold working">[[File:Strain hardening of AuAg30 AuPt10 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg30 AuPt10 by cold working</caption>]]</figure>

Fig. 2.13<figure id="fig: Strain hardening of AuNi5 AuAg20 by cold working">[[File:Strain hardening of AuNi5 AuAg20 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuNi5 AuAg20 by cold working</caption>]]</figure>

Fig. 2.14<figure id="fig: Softening Strain hardening of AuNi5 after annealing for 0.5 hrs after 80% AuAg30 by cold working">[[File:Softening Strain hardening of AuNi5 after annealing for 0.5 hrsAuAg30 by cold working.jpg|rightleft|thumb|Softening <caption>Strain hardening of AuNi5 after annealing for 0.5 hrs after 80% AuAg30 by cold working</caption>]]</figure>

Fig. 2.15<figure id="fig: Strain hardening of AuCo5 AuNi5 by cold working">[[File:Strain hardening of AuCo5 AuNi5 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of 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 0.5 hrs. 2jpg|left|thumb|<caption>Softening of AuNi5 after annealing for 0.165 hrs after 80% cold working</caption>]]</figure> <figure id="fig: Precipitation Strain hardening of AuCo5 at 400°C hardening temperatureby cold working">[[File:Precipitation Strain hardening of AuCo5 atby cold working.jpg|rightleft|thumb|Precipitation <caption>Strain hardening of AuCo5 at 400°C hardening temperatureby cold working</caption>]]</figure>

Fig. 2.17<figure id="fig: Strain Precipitation hardening of AuAg25Pt6 by cold workingAuCo5 at">[[File:Strain Precipitation hardening of AuAg25Pt6 by cold workingAuCo5 at.jpg|rightleft|thumb|Strain <caption>Precipitation hardening of AuAg25Pt6 by cold workingAuCo5 at 400°C hardening temperature</caption>]]</figure>

Fig<figure id="fig:Strain hardening of AuAg25Pt6 by cold working">[[File:Strain hardening of AuAg25Pt6 by cold working. 2.18jpg|left|thumb|<caption>Strain hardening of AuAg25Pt6 by cold working</caption>]]</figure> <figure id="fig: Strain 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>

Fig. 2.19<figure id="fig: Softening of AuAg26Ni3 after annealing for 0.5 -hrs after 80% cold working">[[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>

Fig. 2.20<figure id="fig: Strain 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>

Fig. 2.21<figure id="fig: Strain 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>

Fig. 2.22<figure id="fig: Softening of AuAg20Cu10 after annealing for 0.5 hrs after 80% cold working">[[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>

Fig. 2.23<figure id="fig: Strain 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>

Fig. 2.24<figure id="fig: Precipitation hardening of AuCu14Pt9Ag4 at different hardening temperatures after 50% cold working">[[File:Precipitation hardening of AuCu14Pt9Ag4.jpg|rightleft|thumb|<caption>Precipitation hardening of AuCu14Pt9Ag4 at different hardening temperatures after 50% cold working</caption>]]</figure></div><div class="clear"></div>