page18
Composition
Melting point (°C)
Toxic
Eutectic
Comments
Solidus
Liquidus
Pb
92.5
In
5
Ag
2.5
300
310
[5]
Pb
No
UNS L51510. Minimal leaching of gold, good thermal fatigue properties. Reducing atmosphere frequently used..
Pb
92.5
In
5
Au
2.5
300
310
[6]
Pb
No
In5
Pb
94.5
Ag
5.5
305
304
364
[6]
343
[32]
Pb
No
Ag5.5, UNS L50180
Pb
95
Ag
5
305
364
[33]
Pb
No
Pb
97.5
Ag
2.5
303
[5]
304
[6]
Pb
Yes
Ag2.5, UNS L50132. Used during World War II to conserve tin. Poor corrosion resistance; joints suffered corrosion in both atmospheric and underground conditions, all had to be
replaced with Sn-Pb alloy joints.
[34]
Torch solder.
304
579
[35]
Sn
97.5
Pb
1
Ag
1.5
305
Pb
Yes
Important for hybrid circuits assembly.
[15]
Pb
97.5
Ag
1.5
Sn
1
309
[5]
Pb
Yes
Ag1.5, ASTM1.5S. High melting point, used for commutators, armatures, and initial solder joints where remelting when working on nearby joints is undesirable.
[12]
Silver content
reduces solubility of silver coatings in molten solder. Not recommended for gold.
[8]
Standard PbAgSn eutectic solder, wide use in semiconductor assembly. Reducing protective
atmosphere (e.g. 12% hydrogen) often used. High creep resistance, for use at both elevated and cryogenic temperatures.
Pb
54
Sn
45
Ag
1
177
210
Pb
exceptional strength, silver gives it a bright long-lasting finish; ideal for stainless steel
[12]
Pb
96
Ag
4
305
Pb
high-temperature joints
[12]
Pb
96
Sn
2
Ag
2
252
295
[6]
Pb
Pb96
Sn
61
Pb
36
Ag
3
205
[36]
Pb
[15]
Often referred as POS61 (Russian: ПОС61) in Russia (silver may not be necessarily present).
Sn
56
Pb
39
Ag
5
Pb
[15]
Sn
98
Ag
2
No
[15]
Sn
65
Ag
25
Sb
10
233
No
Yes
Very high tensile strength. For die attachment. Very brittle. Old Motorola die attach solder.
Sn
96.5
Ag
3.0
Cu
0.5
217
220
218
[6][37]
No
Near
SAC305. It is the JEITA recommended alloy for wave and reflow soldering, with alternatives SnCu for wave and SnAg and SnZnBi for reflow soldering. Usable also for selective
soldering and dip soldering. At high temperatures tends to dissolve copper; copper buildup in the bath has detrimental effect (e.g. increased bridging). Copper content must be
maintained between 0.4–0.85%, e.g. by refilling the bath with Sn
97
Ag
3
alloy. Nitrogen atmosphere can be used to reduce losses by dross formation. Dull, surface shows formation of
dendritic tin crystals. Weakens at thermal cycling, concern of whisker growth, large Ag
3
Sn intermetallic platelet precipitates causing mechanical weakening and poor shock/drop
performance. Tendency to creep.
[38]
Sn
98.5
Ag
1.0
Cu
0.5
220
225
No
Near
SAC105 alloy contains the least amount of silver among lead-free solders. It is compatible with all flux types and is relatively inexpensive; it exhibits good fatigue resistance, wetting
and solder joint reliability
Sn
95.8
Ag
3.5
Cu
0.7
217
218
No
Near
SN96C-Ag3.5 A commonly used alloy. Used for wave soldering. Usable also for selective soldering and dip soldering. At high temperatures tends to dissolve copper; copper buildup
in the bath has detrimental effect (e.g. increased bridging). Copper content must be maintained between 0.4–0.85%, e.g. by refilling the bath with Sn
96.5
Ag
3.5
alloy (designated e.g.
SN96Ce). Nitrogen atmosphere can be used to reduce losses by dross formation. Dull, surface shows formation of dendritic tin crystals.
Sn
95.6
Ag
3.5
Cu
0.9
217
No
Yes
Determined by NIST to be truly eutectic.
Sn
95.5
Ag
3.8
Cu
0.7
217
[39]
No
Near
SN96C. Preferred by the European IDEALS consortium for reflow soldering. Usable also for selective soldering and dip soldering. At high temperatures tends to dissolve copper;
copper buildup in the bath has detrimental effect (e.g. increased bridging). Copper content must be maintained between 0.4–0.85%, e.g. by refilling the bath with Sn
96.2
Ag
3.8
alloy
(designated e.g. SN96Ce). Nitrogen atmosphere can be used to reduce losses by dross formation. Dull, surface shows formation of dendritic tin crystals.
Sn
95.25
Ag
3.8
Cu
0.7
Sb
0.25
No
Preferred by the European IDEALS consortium for wave soldering.
Sn
95.5
Ag
3.9
Cu
0.6
217
[40]
No
Yes
Recommended by the US NEMI consortium for reflow soldering. Used as balls for BGA/CSP and CBGA components, a replacement for Sn
10
Pb
90
. Solder paste for rework of BGA
boards.
[7]
Alloy of choice for general SMT assembly.
Sn
95.5
Ag
4
Cu
0.5
217
[41]
No
Yes
SAC405. Lead-Free, Cadmium Free formulation designed specifically to replace Lead solders in Copper and Stainless Steel plumbing, and in electrical and electronic applications.
[3]
Sn
96.5
Ag
3.5
221
[5]
No
Yes
Sn96, Sn96.5, 96S. Fine lamellar structure of densely distributed Ag
3
Sn. Annealing at 125 °C coarsens the structure and softens the solder.
[7]
Creeps via dislocation climb as a result
of lattice diffusion.
[42]
Used as wire for hand soldering rework; compatible with SnCu
0.7
, SnAg
3
Cu
0.5
, SnAg
3.9
Cu
0.6
, and similar alloys. Used as solder spheres for BGA/CSP
components. Used for step soldering and die attachment in high power devices. Established history in the industry.
[7]
Widely used. Strong lead-free joints. Silver content minimizes
solubility of silver coatings. Not recommended for gold.
[8]
Marginal wetting. Good for step soldering. Used for soldering stainless steel as it wets stainless steel better than other soft
solders. Silver content does not suppress dissolution of silver metallizations.
[17]
High tin content allows absorbing significant amount of gold without embrittlement.
[43]
Sn
96
Ag
4
221
229
No
No
ASTM96TS. "Silver-bearing solder". Food service equipment, refrigeration, heating, air conditioning, plumbing.
[12]
Widely used. Strong lead-free joints. Silver content minimizes
solubility of silver coatings. Not recommended for gold.
[8]
Sn
95
Ag
5
221
254
[44]
No
No
Widely used. Strong lead-free joints. Silver content minimizes solubility of silver coatings. Not recommended for gold. Produces strong and ductile joints on Copper and Stainless
Steel. The resulting joints have high tolerance to vibration and stress, with tensile strengths to 30,000 psi on Stainless.
[44]
Sn
94
Ag
6
221
279
[44]
No
No
Produces strong and ductile joints on Copper and Stainless Steel. The resulting joints have high tolerance to vibration and stress, with tensile strengths to 30,000 psi on Stainless.
[44]