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Solder Alloy Melting Point Reference Table: SAC305, Sn63Pb37 and More

When you set a reflow profile, choose a repair alloy or review a customer spec, you need the melting range of the alloy in front of you. This reference lists common solder alloys with composition, solidus and liquidus temperatures.

Download:
AlloyCommon nameSolidus (deg C)Liquidus (deg C)TypeLead-freeTypical use
Sn63Pb37
Eutectic tin-lead
183
183
Eutectic
No
Legacy SMT and hand soldering where permitted
Sn60Pb40
60/40 tin-lead
183
190
Non-eutectic
No
Hand soldering, wave
Sn62Pb36Ag2
Silver-bearing tin-lead
179
179
Eutectic
No
Silver-metallized parts, reduced leaching
Sn96.5Ag3.0Cu0.5
SAC305
217
220
Near-eutectic
Yes
Most common lead-free SMT paste
Sn95.5Ag3.8Cu0.7
SAC387
217
220
Near-eutectic
Yes
Lead-free SMT and wave in some regions
Sn95.5Ag4.0Cu0.5
SAC405
217
220
Near-eutectic
Yes
Lead-free SMT paste
Sn99Ag0.3Cu0.7
SAC0307
217
228
Non-eutectic
Yes
Low-silver lead-free paste and wave
Sn99.3Cu0.7
Tin-copper
227
227
Eutectic
Yes
Lead-free wave soldering
Sn96.5Ag3.5
Tin-silver
221
221
Eutectic
Yes
Lead-free assembly, step soldering
Sn42Bi58
Tin-bismuth
138
138
Eutectic
Yes
Low-temperature reflow for heat-sensitive parts
Sn91Zn9
Tin-zinc
199
199
Eutectic
Yes
Niche applications, needs controlled atmosphere
Sn95Sb5
Tin-antimony
235
240
Non-eutectic
Yes
Higher temperature joints, step soldering
In52Sn48
Indium-tin
118
118
Eutectic
Yes
Very low temperature, thermally sensitive parts
Au80Sn20
Gold-tin
280
280
Eutectic
Yes
Hermetic packages, optoelectronics die attach
Pb92.5Sn5Ag2.5
High-lead
287
296
Non-eutectic
No
High-temperature die attach (exempt uses only)
Pb95Sn5
95/5 high-lead
308
312
Non-eutectic
No
High-temperature step soldering (exempt uses only)

Temperatures are nominal and vary slightly by source and measurement method. Confirm against your paste or wire datasheet. RoHS status refers to the alloy's lead content; exemptions and customer rules vary.

Link process specs to ERP records

An optional review of tying controlled process documents to items and routings.

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How to use the table

Search by alloy name, common name such as SAC305, or use. Solidus is the temperature at which melting begins and liquidus is where the alloy is fully liquid. For a eutectic alloy the two are equal. Your reflow profile must take the joint comfortably above liquidus and hold for the time above liquidus (TAL) in the paste datasheet. Export the table to PDF or Excel for your process documentation.

  • Pb-free SAC alloys reflow with peaks well above 235 deg C
  • Sn42Bi58 enables peak temperatures near 170 deg C
  • Mixing alloys on one board needs extra care at rework

Reading the numbers

The gap between solidus and liquidus is the pasty range. Non-eutectic alloys such as SAC0307 solidify over a wider range, which can lead to disturbed joints if parts move during cooling. Near-eutectic SAC alloys have a narrow 3 degree range and behave almost like a eutectic. Peak reflow temperature is typically 15 to 30 degrees above liquidus for lead-free, limited by the component maximum from J-STD-020.

Common mistakes

A frequent mistake is reflowing a Sn-Pb board with a lead-free profile or the reverse, which damages parts or gives unwetted joints. Backward compatibility between Pb-free parts and Sn-Pb solder is a particular issue for BGAs, where the ball may not collapse fully. Low-temperature bismuth alloys also contaminate Sn-Pb and SAC joints if mixed, creating weak low-melting phases. Verify alloy, flux type and datasheet profile before every new product release.

Frequently Asked Questions

What is the melting point of SAC305?

SAC305 (Sn96.5Ag3.0Cu0.5) begins melting at about 217 deg C and is fully liquid at about 220 deg C. Reflow peak temperatures are normally set 15 to 30 degrees above that, within the component limits.

What is a eutectic solder?

A eutectic alloy melts and solidifies at one single temperature rather than over a range. Sn63Pb37 at 183 deg C and Sn42Bi58 at 138 deg C are well-known examples. This gives sharp solidification and fewer disturbed joints.

Can I mix lead-free and tin-lead solder?

It is possible but risky. Mixed alloys can form low-melting phases and unreliable joints, and Pb-free BGAs on Sn-Pb profiles may not collapse fully. Follow your customer's requirements and IPC guidance, and avoid mixing where reliability matters.

Why is solidus different from liquidus?

Alloys that are not at a eutectic composition melt over a temperature range. Solidus is where the first liquid forms and liquidus is where the last solid dissolves. Reflow must exceed the liquidus to form a proper joint.

Netray can connect process documents such as alloy and profile specs to the item and routing records in your ERP so operators work from the controlled version.

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