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Created page with "The reliability and electrical life of contact systems in switching devices as well as in electromechanical and electronic components do not only depend on the contact materia..."
The reliability and electrical life of contact systems in switching devices as well
as in electromechanical and electronic components do not only depend on the
contact material. The selection of the most suitable carrier material also plays
an important role.
The most frequently used ones are copper based materials. Depending on the
application also materials based on nickel or multi-layer composite materials,
such as thermo bimetals for example, are frequently used. For special
applications in the medium and high voltage technology, as well as for springs
and snap discs for the information technology, iron or steel based materials are
considered. These are however not included for the purpose of this data book.
Various requirements based on the enduse of the contact components have to
be met by carrier materials. Copper materials have to exhibit high electrical and
thermal conductivity, good mechanical strength even at elevated temperatures,
and in addition a sufficient high resistance against corrosion. If used as springs
the carrier materials also must have good elastic spring properties. Besides
these, the materials must, depending on the manufacturing processes
employed, also have good technological properties like ductility to allow warm
and cold forming, suitability for cutting and stamping, and be capable to be
welded, brazed or coated by electroplating
===5.1 Copper and Copper Alloys===
====5.11 Standards Overview====
alloys to be used in electrical and electronic components
are usually covered by national and international standards. DIN numbers the
materials by a prefix and/or a material number. The newer European standards
(EN) refer to the material's usage products and also show a prefix and material
number. For reference we also show in table 5.1 the material designation
according to UNS, the Unified Numbering System (USA). Other internationally
used standard and material numbers include, among others, those issued by
CDA (Copper Development Association, USA), and GB (Guo Biao – China).
The most important EN as well as the US based and widely used ASTM
standards covering the use of flat rolled copper and copper alloys in electrical
contacts are:
{| class="twocolortable" style="text-align: left; font-size: 12px"
|-
!Standard Designation
!D e s c ription
|-
|DIN EN 1652
|Copper and copper alloys in plate, sheet, strip, and discs for general applications
|-
|DIN EN 1654
|Copper and copper alloys for springs and connectors
|-
|DIN EN 1758
|Copper and copper alloys in strip form for system component carriers
|-
|ASTM B 103/B103M-10 ||Spec. for Phosphor Bronce Plate, Sheet, Strip, and Rolled Bar
|-
|ASTM B 36/B36M-95 || Spec. for Brass Plate, Sheet, Strip, and Rolled Bar
|-
|ASTM B 122/B122M-08 || Spec. for CuNiSn-, CuNiZn-, and CuNi-Alloy
|-
|ASTM B 465-09 || Spec. for Copper-Iron-Alloy Plate, Sheet, and Strip
|-
|ASTM B 194-08 || Standard Spec. for CuBe-Alloy Plate, Sheet, Strip and Rolled Bar
|-
|ASTM B 534-07 || Sec. for CuCoBe-Alloy and CuNiBe-Alloy Plate, Sheet, Strip, and Rolled Bar
|}
The above DIN EN standards replace in part or completely the older DIN standards DIN 1777,
DIN 17670, DIN 1751, DIN 1791.
====5.1.2 Pure Copper====
Copper is used in electrical engineering mostly because of its high electrical
conductivity which with 58 MS/m (or m/Ωmm²) is only slightly below that of
silver. Other advantages of copper are its high thermal conductivity, corrosion
resistance, and its good ductility. The work hardening properties of ETP copper
is illustrated in Fig. 5.1. The increase in strength achieved by cold working can
be reversed easily by subsequent annealing. The softening properties are
strongly dependent on the preceding cold working percentage
(Figs. 5.2 and 5.3).
The purity of technically pure and un-alloyed copper used for electrical
applications depends on the type used and ranges between > 99.90 and 99.95
wt%. The copper types are designated mainly by their oxygen content as
oxygen containing, oxygen-free, and de-oxidized with phosphorus as
described in DIN EN 1652 (Tables 5.1 and 5.2).Tables 5.3. and 5.4 show the
physical and mechanical properties of these copper materials. According to
these, Cu-ETP, Cu-OFE, and Cu-HCP are the types of copper for which
minimum values for the electrical conductivity are guaranteed.
Cu-ETP is less suitable for welding or for brazing in reducing atmosphere
because of the oxygen content (danger of hydrogen embrittlement).
Cu-HCP, Cu-DLP, and Cu-DHP are oxygen free copper types de-oxidized with
different phosphorus contents. With increasing phosphorus content the
electrical conductivity decreases. Cu-OFE, also called OFHC copper, is free of
oxygen and also free of de-oxidizing compounds.
*) As units for electrical conductivity MS/m and m/Ω.mm² are commonly used. Frequently – and
mostly in North America – the % IACS value (International Annealed Copper Standard) is also used,
2 where 100% is equivalent to 58 MS/m or m/Ωmm .For the description of mechanical strength
2 properties the units of N/mm or MPa are most commonly used:
2 1 MS/m = 1 m/Ωmm
2 1 MPa = 1 N/mm
5.1.2 Pure Copper
......
[[File:Strain_hardering.png|left|Fig 5.1: Strain_hardening of Cu-ETP by cold working]]
[[File:SofteningOfCuETPafterAnnealing.png|right|Fig. 5.2:Softening of Cu-ETP after annealing for 3hrs after 25% cold working]]
[[Category:Metal Powders|Category]]
[[Category:Thermal conductivity|Category]]
[[Category:Copper|Category]]
as in electromechanical and electronic components do not only depend on the
contact material. The selection of the most suitable carrier material also plays
an important role.
The most frequently used ones are copper based materials. Depending on the
application also materials based on nickel or multi-layer composite materials,
such as thermo bimetals for example, are frequently used. For special
applications in the medium and high voltage technology, as well as for springs
and snap discs for the information technology, iron or steel based materials are
considered. These are however not included for the purpose of this data book.
Various requirements based on the enduse of the contact components have to
be met by carrier materials. Copper materials have to exhibit high electrical and
thermal conductivity, good mechanical strength even at elevated temperatures,
and in addition a sufficient high resistance against corrosion. If used as springs
the carrier materials also must have good elastic spring properties. Besides
these, the materials must, depending on the manufacturing processes
employed, also have good technological properties like ductility to allow warm
and cold forming, suitability for cutting and stamping, and be capable to be
welded, brazed or coated by electroplating
===5.1 Copper and Copper Alloys===
====5.11 Standards Overview====
alloys to be used in electrical and electronic components
are usually covered by national and international standards. DIN numbers the
materials by a prefix and/or a material number. The newer European standards
(EN) refer to the material's usage products and also show a prefix and material
number. For reference we also show in table 5.1 the material designation
according to UNS, the Unified Numbering System (USA). Other internationally
used standard and material numbers include, among others, those issued by
CDA (Copper Development Association, USA), and GB (Guo Biao – China).
The most important EN as well as the US based and widely used ASTM
standards covering the use of flat rolled copper and copper alloys in electrical
contacts are:
{| class="twocolortable" style="text-align: left; font-size: 12px"
|-
!Standard Designation
!D e s c ription
|-
|DIN EN 1652
|Copper and copper alloys in plate, sheet, strip, and discs for general applications
|-
|DIN EN 1654
|Copper and copper alloys for springs and connectors
|-
|DIN EN 1758
|Copper and copper alloys in strip form for system component carriers
|-
|ASTM B 103/B103M-10 ||Spec. for Phosphor Bronce Plate, Sheet, Strip, and Rolled Bar
|-
|ASTM B 36/B36M-95 || Spec. for Brass Plate, Sheet, Strip, and Rolled Bar
|-
|ASTM B 122/B122M-08 || Spec. for CuNiSn-, CuNiZn-, and CuNi-Alloy
|-
|ASTM B 465-09 || Spec. for Copper-Iron-Alloy Plate, Sheet, and Strip
|-
|ASTM B 194-08 || Standard Spec. for CuBe-Alloy Plate, Sheet, Strip and Rolled Bar
|-
|ASTM B 534-07 || Sec. for CuCoBe-Alloy and CuNiBe-Alloy Plate, Sheet, Strip, and Rolled Bar
|}
The above DIN EN standards replace in part or completely the older DIN standards DIN 1777,
DIN 17670, DIN 1751, DIN 1791.
====5.1.2 Pure Copper====
Copper is used in electrical engineering mostly because of its high electrical
conductivity which with 58 MS/m (or m/Ωmm²) is only slightly below that of
silver. Other advantages of copper are its high thermal conductivity, corrosion
resistance, and its good ductility. The work hardening properties of ETP copper
is illustrated in Fig. 5.1. The increase in strength achieved by cold working can
be reversed easily by subsequent annealing. The softening properties are
strongly dependent on the preceding cold working percentage
(Figs. 5.2 and 5.3).
The purity of technically pure and un-alloyed copper used for electrical
applications depends on the type used and ranges between > 99.90 and 99.95
wt%. The copper types are designated mainly by their oxygen content as
oxygen containing, oxygen-free, and de-oxidized with phosphorus as
described in DIN EN 1652 (Tables 5.1 and 5.2).Tables 5.3. and 5.4 show the
physical and mechanical properties of these copper materials. According to
these, Cu-ETP, Cu-OFE, and Cu-HCP are the types of copper for which
minimum values for the electrical conductivity are guaranteed.
Cu-ETP is less suitable for welding or for brazing in reducing atmosphere
because of the oxygen content (danger of hydrogen embrittlement).
Cu-HCP, Cu-DLP, and Cu-DHP are oxygen free copper types de-oxidized with
different phosphorus contents. With increasing phosphorus content the
electrical conductivity decreases. Cu-OFE, also called OFHC copper, is free of
oxygen and also free of de-oxidizing compounds.
*) As units for electrical conductivity MS/m and m/Ω.mm² are commonly used. Frequently – and
mostly in North America – the % IACS value (International Annealed Copper Standard) is also used,
2 where 100% is equivalent to 58 MS/m or m/Ωmm .For the description of mechanical strength
2 properties the units of N/mm or MPa are most commonly used:
2 1 MS/m = 1 m/Ωmm
2 1 MPa = 1 N/mm
5.1.2 Pure Copper
......
[[File:Strain_hardering.png|left|Fig 5.1: Strain_hardening of Cu-ETP by cold working]]
[[File:SofteningOfCuETPafterAnnealing.png|right|Fig. 5.2:Softening of Cu-ETP after annealing for 3hrs after 25% cold working]]
[[Category:Metal Powders|Category]]
[[Category:Thermal conductivity|Category]]
[[Category:Copper|Category]]
