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Composition by weight %
Family
Solidus/liquidus
point (°C)
Toxic
Comments
Cu
Zn
Ag
Au
Pd
Pt
Ti
Cr
Mo
W
Mn
Fe
Co
Ni
Cd
Sn
Al
B
Si
P
other
Au
80
Sn
20
Au
280
[54]
–
Au80, Indalloy 182, Premabraze 800, Orotin. Good wetting, high strength, low
creep, high corrosion resistance, high thermal conductivity, high surface tension,
zero wetting angle. Limited ductility. Suitable for step soldering. The original flux-
less alloy, does not need flux. Used for die attachment and attachment of metal lids
to semiconductor packages, e.g. kovar lids to ceramic chip carriers. Coefficient of
expansion matching many common materials. Due to zero wetting angle requires
pressure to form a void-free joint. Alloy of choice for joining gold-plated and gold-
alloy plated surfaces. As some gold dissolves from the surfaces during soldering
and moves the composition to non-eutectic state (1% increase of Au content can
increase melting point by 30 °C), subsequent desoldering requires higher
temperature.
[76]
Forms a mixture of two brittle intermetallic phases, AuSn and
Au
5
Sn.
[77]
Brittle. Proper wetting achieved usually by using nickel surfaces with
gold layer on top on both sides of the joint. Comprehensively tested through military
standard environmental conditioning. Good long-term electrical performance,
history of reliability.
[78]
Low vapor pressure, suitable for vacuum work. Good
ductility. Also classified as a solder. Lowest melting point alloy with low vapor
pressure.
80
20
Au
88
Ge
12
Au
356
[54]
–
Au88, Indalloy 183, Premabraze 880, Georo. Eutectic. Low ductility. Used for die
attachment of some chips. The high temperature may be detrimental to the chips
and limits reworkability. Very low vapor pressure.
88
Ge
12
Ag
90
Ge
10
Ag
651/790
[73]
–
Low vapor pressure. Copper-free. Much lower thermal conductivity than silver. Low
tarnishing due to germanium content; transparent passivation layer of germanium
oxide protects against silver sulfide formation. Can be precipitation-hardened. See
also Argentium sterling silver.
90
Ge
10
Ag
82
Pd
9
Ga
9
Ag-Pd
845/880
[73]
–
Gapasil 9. Ductile. Corrosion-resistant. For brazing titanium to titanium and
titanium to stainless steel.
82
9
Ga
9
Cu
62
Au
35
Ni
3
Au–Cu
974/1029
[54][75]
–
BAu-3, Premabraze 127, Nicoro. For nickel, kovar, stainless steel, molybdenum,
and molybdenum-manganese metallized ceramics. Excellent wetting, low base
metal erosion.
62
35
3
Au
35
Cu
31.5
Ni
14
Pd
10
Mn
9.5
Au-Pd
971/1004
[73]
–
RI-46. For tungsten carbide and superalloys.
31.5
35
10
9.5
14
Au
82
Ni
18
Au-Ni
950
[1]
955
[73]
–
BAu-4, BVAu-4, AU 105, Premabraze 130, Premabraze 131 (vacuum grade),
AMS 4787, Nioro, Gold Braze 8218. Eutectic. Excellent wetting. Ductile. Oxidation
resistance exceeds palladium-bearing alloys. High mechanical strength at high
temperatures. Nickel gray color. For stainless steel, tungsten, all common iron and
nickel refractory alloys, Inconel X, A286, Kovar, and similar alloys. Normally not
used for copper or silver-based alloys; flow point close to melting point of silver,
and too readily alloys with copper. Low penetration of base metal, suitable for
brazing thin parts, e.g. thin-wall tubing or vacuum tubes. Does not produce severe
intergranular penetrations characteristic for boron-containing nickel brazing alloys.
Extensively used in nuclear industry except in high-neutron flux regions and in
contact with liquid sodium or potassium. Oxidation and scaling resistance up to 815
°C. Brazing done in inert atmospheres or vacuum.
82
18
Au
82
In
18
Au
451/485
–
Au82, Indalloy 178. High-temperature solder, extremely hard, very stiff.
82
In
18
Au
60
Cu
37
In
3
Au–Cu
860/900
[73]
–
Incuro 60. Lower brazing temperature than other Au–Cu.
37
60
In
3
Au
20
Cu
68
In
2
Au–Cu
975/1025
[73]
–
Incuro 20. Cheaper substitute of BAu-3 and other gold-rich gold-copper alloys.
68
20
In
2
Au
72
Pd
22
Cr
6
Au-Pd
975/1000
[73]
–
Croniro. For brazing diamond to stainless steel. Minimizes chromium depletion of
base metals. High corrosion resistance.
72
22
6
Au
75
Ni
25
Au-Ni
950/990
[1]
–
AU 106. Oxidation resistance exceeds palladium-bearing alloys. High mechanical
strength at high temperatures.
75
25
Au
73.8
Ni
26.2
Au-Ni
980/1010
[73]
–
Nioro-Ni. For loose tolerances with stainless steel and superalloys. Excellent flow.
73.8
26.2
Au
81.25
Ni
18
Ti
0.75
Au-Ni
945/960
[73]
–
Nioro-Ti. Wets difficult-to-wet metals.
81.25
0.75
18
Au
70
Ni
30
Au-Ni
960/1050
[73]
–
Ductile, oxidation resistant. Flow strength. Excellent wetting.
70
30
Au
75
Cu
20
Ag
5
Au–Cu
885/895
[54]
–
Premabraze 051, Silcoro 75. Narrow melting range, suitable for step brazing.
20
5
75
Au
80
Cu
19
Fe
1
Au–Cu
905/910
[1]
–
AU 101
19
80
1
Au
62.5
Cu
37.5
Au–Cu
930/940
[1]
–
AU 102
37.5
62.5
Au
60
Ag
20
Cu
20
Au–
Ag–Cu
835/845
[54]
–
Premabraze 408, Silcoro 60. Narrow melting range, good for step brazing.
20
20
60
Au
81.5
Cu
16.5
Ni
2
Au–Cu
955/970
[54]
–
Premabraze 409, Nicoro 80. Remains ductile when solid. Low vapor pressure. For
copper, nickel, molybdenum-manganese.
16.5
81.5
2
Au
50
Cu
50
Au–Cu
955/970
[54]
–
Premabraze 402. For copper, nickel, kovar, and molybdenum-manganese
metallized ceramics.
50
50
Au
37.5
Cu
62.5
Au–Cu
980/1000
[1]
985/1005
[73]
–
AU 103. For copper, nickel, kovar, and molybdenum-manganese metallized
ceramics.
62.5
37.5
Au
35
Cu
65
Au–Cu
990/1010
[54]
–
Premabraze 407. For copper, nickel, kovar, and molybdenum-manganese
metallized ceramics.
65
35
Au
30
Cu
70
Au–Cu
995/1020
[1]
–
AU 104
70
30
Ni
36
Pd
34
Au
30
Au–
Pd–Ni
1135/1166
[75]
–
BAu-5, Gold Braze 3034.
30
34
36