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Brazing Alloys
For the joining of contact materials with carrier substrates, brazing alloys with working temperatures > 600 °C are used exclusively. The working temperature is defined as the lowest surface temperature, by which the brazing material wets the materials to be joined. This temperature is within the melting range and between the solidus (temperature at which melting starts) and liquidus (temperature at complete liquid state) point of the brazing alloy. Silver-based brazing alloys have good electrical conductivity and a sufficient mechanical strength, which allows a bonding process without significant changes in the microstructure of the material to be joined.
For electrical contacts, usually low-melting alloys with a minimum of 20 wt-% silver and additions of cadmium, zinc or tin are used to lower the melting point (Table 1). Because of the toxicity of cadmium, most cadmium containing brazing alloys have been replaced by zinc and tin containing brazing alloys. Alloys containing nickel and manganese are also used for higher corrosion resistance requirements or for easier wetting of stainless steel.. Using any of these brazing alloys in an air environment is only possible with the addition of oxide reducing fluxes.
For high temperature brazing in vacuum or protective atmosphere, vacuum melted silver-copper eutectic brazing alloys are used. These also allow subsequent forming operations due to their higher ductility. For the brazing of contacts with a silver bottom layer to copper backings, phosphorous containing brazing alloys which eliminate the need for a flux application, are widely used. The brazing alloy is typically introduced into the joint area in the form of wire segments, foil, shims or as powder or paste. For larger production volumes it is economically advantageous to pre-coat contact tips with a thin layer (≤ 100 µm) of brazing alloy.
Designation DIN EN 1044 |
BrazeTec Designation |
Designation US (equivalent or closest similar brazing alloy) |
Designation DIN EN ISO 3677 |
Composition wt % |
Melting Range (solidus) [°C] |
Melting Range (liquidus) [°C] |
Working Temperature [°C] |
Electrical Conductivity [MS/m] |
Density [g/m3] |
Application |
---|---|---|---|---|---|---|---|---|---|---|
AG103 | BrazeTec 5507 | BAg-7 | B-Ag55ZnCuSn 630/660 |
Ag54 - 56 Cu20 - 23 Zn20 - 24 Sn1,5 - 2,5 |
630 | 660 | 650 | 8,4 | 9,6 | Cu, Cu-Alloys, Ag-materials Fe, Ni |
Ag502 | BrazeTec 4900 | BAg-22 | B-Ag49ZnCuMnNi 680/705 |
Ag48 - 50 Zn21 - 25 Cu15 - 17 Mn6,5 - 8,5 Ni4 - 5 |
680 | 705 | 690 | 4,0 | 8,9 | W, Mo, carbide steel Fe, Ni |
Ag401 | BrazeTec 7200 | BAg-8 | B-Ag72Cu-780 | Ag71 - 73 Cu Rest |
780 | 780 | 780 | 46,1 | 10,0 | Cu, Cu-Alloys, Ag-materials vacuum brazing |
CP 102 | BrazeTec S15 | BCuP-5 | B-Cu80AgP 645/800 |
Ag14,5 - 15,5 P4,7 - 5,3 Cu Rest |
645 | 800 | 710 | 7,0 | 8,4 | Cu, Cu-Legierungen, Ag-materials |
Fluxes
Brazing fluxes consist of non-metallic materials, mostly salt mixtures of boron and halogen compounds (Table 2). Their purpose is to remove oxides from the brazing surfaces and prevent their new build-up, in order to allow a thorough wetting of these surfaces by the liquefied brazing alloy. Fluxes have to be activated already at a temperature below the working range of the brazing alloy. They are selected mainly according to the working temperature of the brazing alloy and the base material to be joined.
Since the residues of fluxes are hygroscopic and can cause corrosion, they have to be removed completely after the brazing process in very hot or boiling water. Depending on the type and process used, fluxes are being applied in liquid form or as powders or pastes.
Designation DIN EN 1045 | Designation US (similar) | Active tempe- rature range [°C] | Chemical ingredients | Base materials used for |
---|---|---|---|---|
TYP FH 10 | FB 3-A | 550 - 800 | Boron compounds, Fluorides | All metals and alloys except light metals, alloyed steels, carbide steels |
TYP FH 11 | FB 4-A | 550 - 800 | Boron compounds, Fluorides, Chlorides | Copper, Aluminum bronze |
TYP FH 12 | FB 3-C | 550 - 850 | Boron, Boron compounds, Fluorides | Special brass, any steel alloys, carbide steel |
TYP FH 21 | FB 3-I | 750 - 1100 | Boron compounds, Chlorides | All metals and alloys except light metals |
References
DIN 8514 Löten metallischer Werkstoffe. Begriffe, Benennungen
DIN EN 1044 Hartlöten, Lötzusätze
DIN EN 1045 Flussmittel zum Hartlöten
ASM Metals, Handbook: Vol 6 Welding, Brazing, and Soldering, ASM, Cleveland, OH, 1993
Dorn, L.: Hartlöten, Grundlagen und Anwendungen. Expert-Verlag, Band 146 (1985)
Krell, A.: Flussmittel und Lötfehler beim Hartlöten. Schweißtechnik, Berlin, 38 (1988)
DVS-Taschenbuch 196: Beuth-Verlag. Berlin, 1997
Müller, W.: Metallische Lotwerkstoffe. Dt. Verlag für Schweißtechnik,
Düsseldorf 1990
Physical Properties of the Most Important Metals
The following tables list the physical properties of the most technically significant pure metals as well as carbon. The values given may vary considerably, depending on the degree of purity and sometimes they are also difficult to determine. In compiling the data from the available literature, we selected those that are currently the most probable. Some properties are anisotropic and vary with the crystalline structure of the metal.</onlyinclude> In those cases, we listed the value applicable to the poly-crystalline stage.
Element/Metal | Density 1
[g/cm³] |
Modulus of
Elasticity 1[GPa] |
Shear Modulus
[GPa] |
Transvers Contraction Coeffic. |
---|---|---|---|---|
Aluminum | 2.70 | 65 | 27 | 0.34 |
Antimony | 6.62 | 56 | 20.4 | 0.28 |
Beryllium | 1.85 | 298 | 150 | 0.12 |
Lead | 11.36 | 14.5 | 6 | 0.44 |
Cadmium | 8.65 | 57.5 | 29 | 0.30 |
Chromium | 7.19 | 160 | 0.25 | |
Iron | 7.89 | 208 | 83 | 0.28 |
Gallium | 5.91 | 9.6 | 0.46 | |
Gold | 19.32 | 79 | 28 | 0.42 |
Indium | 7.31 | 11 | 0.45 | |
Iridium | 22.65 | 538 | 214 | 0.26 |
Cobalt | 8.85 | 216 | 0.31 | |
Carbon (Graphite) | 2.1-2.3 | 5 | ||
Copper | 8.95 | 115 | 48 | 0.34 |
Magnesium | 1.74 | 46 | 18 | 0.28 |
Manganese | 7.43 | 165 | 77 | 0.24 |
Molybdenum | 10.21 | 347 | 122 | 0.30 |
Nickel | 8.90 | 216 | 83 | 0.31 |
Niobium | 8.57 | 113 | 39 | 0.38 |
Osmium | 22.61 | 570 | 220 | 0.25 |
Palladium | 12.02 | 124 | 51 | 0.39 |
Platinum | 21.45 | 173 | 67 | 0.39 |
Mercury | 13.55 | |||
Rhenium | 21.04 | 480 | 215 | 0.26 |
Rhodium | 12.41 | 386 | 153 | 0.26 |
Ruthenium | 12.45 | 485 | 172 | 0.29 |
Silver | 10.49 | 82 | 27 | 0.37 |
Tantalum | 16.60 | 188 | 70 | 0.35 |
Titanium | 4.51 | 120 | 43 | 0.34 |
Vanadium | 6.10 | 136 | 52 | 0.36 |
Bismuth | 9.80 | 33 | 13 | 0.33 |
Tungsten | 19.32 | 360 | 158 | 0.30 |
Zinc | 7.13 | 96 | 36 | 0.29 |
Tin | 7.30 | 47 | 18 | 0.33 |
Zirconium | 6.49 | 98 | 36 | 0.33 |
Element/Metal | Chemical Symbol |
Atomic Number | Atomic Weight | Crystal Structure 1 | Lattic Parameters 1 a or b 2 [1010m] |
Lattic Parameters 1 a or b 2 [10-10m] |
Work Function [eV] |
Ionization Potential [eV] |
---|---|---|---|---|---|---|---|---|
Aluminum | Al | 13 | 26,98 | foc | 4,049 | 4,08 - 4,3 | 5,98 | |
Antimony | Sb | 51 | 121,75 | rhl | 4,507 | 4,1 | 8,64 | |
Beryllium | Be | 4 | 9,01 | hcp | 2,286 | 3,584 | 3,2 - 3,9 | 9,32 |
Lead | Pb | 87 | 207,19 | fcc | 4,949 | 4,0 - 4,1 | 7,42 | |
Cadmium | Cd | 48 | 112,40 | hcp | 2,979 | 5,617 | 3,7 - 4,1 | 8,99 |
Chromium | Cr | 24 | 52,00 | bcc | 2,884 | 4,4 - 4,7 | 6,76 | |
Iron | Fe | 26 | 55,85 | bcc | 2,866 | 4,1 - 4,5 | 7,9 | |
Gallium | Ga | 31 | 69,72 | ort | 4,524 | 7,661 | 3,8 - 4,1 | 6,0 |
Gold | Au | 79 | 196,97 | fcc | 4,078 | 4,3 - 5,1 | 9,22 | |
Indium | In | 49 | 114,82 | tet | 4,594 | 4,951 | 4,0 | 5,79 |
Iridium | Ir | 77 | 192,20 | fcc | 3,839 | 4,6 - 5,3 | 9,1 | |
Cobalt | Co | 27 | 58,93 | hcp | 2,507 | 4,069 | 4,4 - 4,6 | 7,86 |
Carbon (Graphite) | C | 6 | 12,01 | hcp-layered lattic3 | 2,456 | 6,696 | 4,8 | 11,27 |
Copper | Cu | 29 | 63,54 | fcc | 3,615 | 4,4 | 7,72 | |
Magnesium | Mg | 12 | 24,31 | hcp | 3,209 | 5,210 | 3,7 | 7,64 |
Manganese | Mn | 25 | 54,94 | complex cubic | 8,912 | 3,8 - 4,1 | 6,0 | |
Molybdenum | Mo | 42 | 95,94 | bcc | 3,147 | 4,1 - 4,5 | 7,18 | |
Nickel | Ni | 28 | 58,71 | fcc | 3,524 | 5,0 - 5,2 | 7,63 | |
Niobium | Nb | 41 | 92,91 | bcc | 3,301 | 4,0 | 6,77 | |
Osmium | Os | 76 | 190,23 | hcp | 2,734 | 4,320 | 4,5 | 8,7 |
Palladium | Pd | 46 | 106,40 | fcc | 3,890 | 4,5 - 5,0 | 8,34 | |
Platinum | Pt | 78 | 195,09 | fcc | 3,931 | 4,1 - 5,5 | 9,0 | |
Mercury | Hg | 80 | 200,59 | rhl4 | 3,0614 | 4,5 | 10,44 | |
Rhenium | Re | 75 | 186,20 | hcp | 2,760 | 4,458 | 4,7 - 5,0 | 7,8 |
Rhodium | Rh | 45 | 102,91 | fcc | 3,804 | 4,6 - 4,9 | 7,46 | |
Ruthenium | Ru | 44 | 101,07 | hcp | 2,704 | 4,281 | 4,5 | 7,37 |
Silver | Ag | 47 | 107,87 | fcc | 4,086 | 4,3 | 7,57 | |
Tantalum | Ta | 73 | 180,95 | bcc | 3,303 | 4,0 - 4,2 | 7,89 | |
Titanium | Ti | 2 | 47,90 | hcp | 2,950 | 4,683 | 4,0 - 4,4 | 6,83 |
Vanadium | V | 23 | 50,94 | bcc | 3,039 | 3,8 - 4,2 | 6,71 | |
Bismuth | Bi | 83 | 208,98 | rhl | 4,746 | 4,1 - 4,5 | 8,0 | |
Tungsten | W | 74 | 183,85 | bcc | 3,158 | 4,3 - 5,0 | 7,98 | |
Zinc | Zn | 30 | 65,37 | hcp | 2,665 | 4,947 | 3,1 - 4,3 | 9,39 |
Tin | Sn | 50 | 118,69 | tet | 5,831 | 3,181 | 3,6 - 4,1 | 7,33 |
Zirconium | Zr | 40 | 91,22 | hcp | 3,231 | 5,148 | 3,7 - 4,3 | 6,92 |
fcc = cubic face cenered // bcc = cubic body centered // hcp = hexagonal dense spherical
ort = orthorhombic // tet = tetragonal // rhl = rhombohedral
Element/Metal | Specific Heat 1 [kJ/(K*kg)] |
Softening Temperature [°C] |
Melting Point [°C] |
Heat of Fusion [kJ/kg] |
Vapor Pressure at Melting Point [Pa] |
Boiling Point [°C] |
Heat of Vaporizing [kJ/g] |
Thermal Conductivity [W/(m*K)] |
Linear Expansion Coefficient2 [10-6m/K] |
Volume Change at Solidification [%] |
---|---|---|---|---|---|---|---|---|---|---|
Aluminum | 0,900 | 150 | 660 | 398 | 2,5x10-6 | 2467 | 10,47 | 237 | 23,6 | -6,5 |
Antimony | 0,210 | 630 | 163 | 2,5x10-9 | 1587 | 1,97 | 24,3 | 10,5 | +9,5 | |
Beryllium | 1,824 | 1277 | 1090 | 4,3 | 2477 | 200 | 12,3 | |||
Lead | 0,130 | 200 | 327 | 25 | 4,21x10-7 | 1750 | 24,70 | 35,3 | 29,3 | -3,5 |
Cadmium | 0,230 | 321 | 54 | 14,8 | 767 | 0,88 | 96,8 | 41,0 | -4,0 | |
Chromium | 0,450 | 1857 | 314 | 990 | 2672 | 5,86 | 93,7 | 6,2 | ||
Iron | 0,444 | 500 | 1537 | 268 | 7,05 | 2750 | 80,2 | 12,2 | -3,0 | |
Gallium | 0,370 | 29,8 | 80,4 | 9,6x10-36 | 2204 | 3,90 | 40,6 | 18,0 | +3,0 | |
Gold | 0,128 | 100 | 1064 | 63 | 2,4x10-3 | 3080 | 1,55 | 317 | 14,3 | -5,1 |
Indium | 0,233 | 157 | 28,5 | 1,5x10-17 | 2072 | 1,97 | 81,6 | -2,5 | ||
Iridium | 0,130 | 2410 | 144 | 1,5 | 4130 | 3,31 | 147 | 6,5 | ||
Cobalt | 0,420 | 1495 | 260 | 175 | 2927 | 6,66 | 100 | 13,8 | ||
Carbon (Graphite) | 0,720 | 3825 sublimiert | 119 - 165 | 155 | ||||||
Copper | 0,385 | 190 | 1084 | 205 | 5,2x10-2 | 2567 | 4,77 | 401 | 16,5 | -4,2 |
Magnesium | 1,020 | 650 | 373 | 361 | 1107 | 5,44 | 156 | 26,0 | -4,1 | |
Manganese | 0,480 | 1244 | 264 | 121 | 1962 | 4,10 | 7,8 | 23,0 | -1,7 | |
Molybdenum | 0,250 | 900 | 2623 | 292 | 3,6 | 4639 | 5,61 | 138 | 5,2 | |
Nickel | 0,440 | 520 | 1453 | 301 | 237 | 2913 | 6,45 | 90,7 | 13,0 | -2,5 |
Niobium | 0,272 | 2477 | 289 | 7,9x10-2 | 4744 | 7,79 | 53,7 | 7,3 | ||
Osmium | 0,130 | 3045 | 141 | 2,52 | 5012 | 3,81 | 87,6 | 6,5 | ||
Palladium | 0,244 | 1554 | 143 | 1,33 | 2970 | 3,48 | 71,8 | 11,1 | -5,5 | |
Platinum | 0,130 | 540 | 1772 | 113 | 3,2x10-2 | 3827 | 2,62 | 71,6 | 9,0 | -6,0 |
Mercury | 0,140 | -38,9 | 11,7 | 3,1x10-4 | 357 | 0,29 | 8,34 | 60,8 | -3,7 | |
Rhenium | 0,137 | 3186 | 178 | 3,24 | 5596 | 3,42 | 72 | 6,7 | ||
Rhodium | 0,242 | 1966 | 211 | 6,36x10-1 | 3695 | 5,19 | 150 | 8,5 | -10,8 | |
Ruthenium | 0,238 | 2310 | 252 | 1,4 | 4150 | 6,62 | 117 | 9,5 | ||
Silver | 0,232 | 180 | 961,9 | 105 | 3,4x10-1 | 2212 | 2,39 | 429 | 19,5 | -3,8 |
Tantalum | 0,140 | 850 | 3017 | 157 | 7,86x10-1 | 5448 | 4,32 | 57,5 | 6,5 | |
Titanium | 0,520 | 1668 | 403 | 4,9x10-1 | 2830 | 8,80 | 21,9 | 10,8 | ||
Vanadium | 0,490 | 1902 | 330 | 3,06 | 3287 | 10,3 | 30,7 | 8,3 | ||
Bismuth | 0,122 | 271 | 54 | 6,5x10-4 | 1564 | 1,43 | 7,87 | 14,0 | -0,33 | |
Tungsten | 0,138 | 1000 | 3422 | 193 | 4,27 | 5555 | 3,98 | 174 | 4,5 | |
Zinc | 0,385 | 170 | 420 | 100 | 3,06 | 907 | 1,76 | 116 | 36,0 | -4,7 |
Tin | 0,228 | 100 | 222 | 59 | 6x10-21 | 2602 | 1,95 | 66,6 | 26,7 | -2,8 |
Zirconium | 0,281 | 1852 | 224 | 1,7x10-3 | 4409 | 4,6 | 22,7 | 5,9 |
Element/Metal | Electrical Resistivity 1 [Ω*mm2/m] |
Electrical Conductivity1 [MS/m] |
Temperatur Coeff. of Electrical Resistance2 [10-3/K] |
Absolute thermal e.m.f.3 [µV/K] |
Critical Superconductor Temperatur [K] |
Softening Voltage (measured) [V] |
Melting Voltage (measured) [V] |
Melting Voltage (calculated)4 [V] |
Minimum Arc Voltage [V] |
Minimum Arc Current [A] |
---|---|---|---|---|---|---|---|---|---|---|
Aluminum | 2,65 | 37,7 | 4,6 | -1,6 | 1,18 | 0,1 | 0,3 | 0,29 | 11,2 | 0,4 |
Antimony | 38,6 | 2,6 | 5,4 | +20,6 - +46,8 | 0,2 | 0,28 | 10,5 | |||
Beryllium | 4,2 | 23,8 | 10,0 | -3,3 | 0,026 | 0,48 | ||||
Lead | 19,2 | 5,2 | 4,2 | -1,2 | 7,196 | 0,19 | 0,17 | 11,5 | 0,1 | |
Cadmium | 7,50 | 13,30 | 4,3 | -0,1 - +3,6 | 0,52 | 0,12 | 0,17 | 12 | 0,4 | |
Chromium | 14,95 | 6,7 | 3,0 | +14,0 | 3,0 | 0,67 | 16 | 0,45 | ||
Iron | 9,72 | 10,3 | 6,6 | +16,0 | 0,19 | 0,6 | 0,54 | 11,5 | ||
Gallium | 43,2 | 2,3 | 4,0 | 1,08 | 0,04 | 0,35 | ||||
Gold | 2,35 | 42,6 | 4,0 | +1,7 | 0,08 | 0,43 | 0,42 | 15 | ||
Indium | 8,37 | 11,94 | 4,9 | 3,41 | 0,11 | |||||
Iridium | 5,31 | 18,83 | 4,1 | +1,5 | 0,11 | 0,86 | 11,5 | |||
Cobalt | 6,24 | 16,0 | 6,6 | -18,5 | 0,54 | 0,01 - 0,02 | ||||
Carbon (Graphite) | 30,0 | 3,33 | 20 | 0,4 | ||||||
Copper | 1,67 | 59,9 | 4,3 | +1,7 | 0,12 | 0,43 | 0,42 | 12 - 13 | ||
Magnesium | 4,42 | 22,62 | 4,2 | +3,4 | 0,28 | |||||
Manganese | 185,0 | 0,54 | 0,5 | 0,47 | 0,75 | |||||
Molybdenum | 5,20 | 19,2 | 4,7 | +5,9 | 0,92 | 0,3 | 0,75 | 0,91 | 12 | 0,4 -0,5 |
Nickel | 6,85 | 14,6 | 6,8 | -18,9 | 0,16 | 0,65 | 0,54 | 14 | ||
Niobium | 13,1 | 7,6 | 3,4 | -0,5 | 9,2 | 0,778 | ||||
Osmium | 8,12 | 12,31 | 4,2 | 0,66 | 1,04 | 0,8 -0,9 | ||||
Palladium | 10,82 | 9,24 | 3,8 | -0,9 | 3,3 | 0,57 | 0,57 | 15 - 16 | 0,8 -1,0 | |
Platinum | 10,54 | 9,58 | 3,9 | -4,4 | 0,0019 | 0,25 | 0,71 | 0,64 | 17 | |
Mercury | 94,9 | 1,14 | 1,0 | +8,5 | 4,15 | 0,35 | ||||
Rhenium | 19,3 | 5,2 | 4,6 | 1,7 | 1,09 | |||||
Rhodium | 4,51 | 22,2 | 4,4 | +1,7 | 0,000325 | 0,70 | 14 | |||
Ruthenium | 7,62 | 13,12 | 4,6 | -18,0 | 0,49 | 0,81 | 0,4 | |||
Silver | 1,59 | 62,9 | 4,3 | +1,4 | 0,09 | 0,37 | 0,38 | 12 | ||
Tantalum | 12,4 | 8,1 | 3,5 | -2,3 | 4,47 | 0,3 | 1,03 | 12 | ||
Titanium | 43,5 | 2,3 | 5,5 | +7,3 | 0,4 | 0,61 | ||||
Vanadium | 26,0 | 3,8 | 3,9 | +1,0 | 5,3 | 0,68 | ||||
Bismuth | 12,1 | 8,36 | 4,5 | -53 - -110 | 0,15 | |||||
Tungsten | 5,65 | 17,7 | 4,8 | +0,8 | 0,0154 | 1,1 | 1,16 | 1,16 | 0,8 - 1,2 | |
Zinc | 5,92 | 16,9 | 4,2 | +0,4 - +2,3 | 0,85 | 0,17 | 0,2 | 0,20 | 15 - 16 | 0,1 |
Tin | 11,0 | 9,09 | 4,6 | -0,6 - -1,5 | 3,72 | 0,13 | 0,14 | 0,14 | 11 | |
Zirconium | 43,5 | 2,3 | 4,4 | +9,5 | 0,55 | 0,67 | 0,67 | 12,5 |
References
Metals Handbook, Desk Edition: Chicago, IL, American Society of Metal, 1985
Landolt-Börnstein: Zahlenwerte und Funktionen. Springer-Verlag, Berlin-Göttingen-Heidelberg, 1959
Handbook of Chemistry and Physics, 70th Edition: CRC Press., Inc. Boca Raton, Florida, 1989 - 1990
Fluck, E.; Heumann, K., G.: Periodensystem der Elemente. Weinheim: VCH-Verlagsgesellschaft, 1986
Kieffer, R.; Jangg, G.; Ettmayer, P.: Sondermetalle. Springer- Verlag, Wien-New York, 1963
Hering, E.; Schulz, W.: Physik für Ingenieure (Periodensystem der Elemente). Düsseldorf: VDI-Verlag, 1988
Degussa AG (Hrsg.): Edelmetall-Taschenbuch. Hüthig-Verlag, Heidelberg, 1995
Slade, P.; G. (editor): Electrical Contacts Principles and Applications. Marcel Dekker, Inc., New York-Basel, 1999
Gerritsen, A.; N.: Metallic Conductivity in: Flügge, S.: Handbuch der Physik, Bd. 19, Springer-Verlag, Berlin-Göttingen-Heidelberg, 1956
Köster, W.; Franz, H.: Poisson,s Ratio for Metals and Alloys. Metallurg. Reviews 6 (1961)
Nesmeyanow, A., N.: Vapor Pressure of the Chemical Elements: Elsevier, Amsterdam-London-New York, 1963
Wyckoff, R., W., G.: Crystal Structures. Vol 1,New York, 1963 Special:Example