01 — Temperature Columns
Solidus
The temperature at which the alloy begins to melt. Below this point the solder is fully solid. In a reflow oven, time above solidus is what closes the joint, so a lower solidus gives you more margin if your oven has poor thermal uniformity.
Liquidus
The temperature at which the alloy is fully liquid. Reflow peak temperature must exceed liquidus to achieve wetting. A higher liquidus means you need a hotter oven and more thermal stress on components.
Pasty Range
The gap between solidus and liquidus. In this semi-solid state the alloy is sensitive to vibration and movement. A wide pasty range increases the risk of disturbed joints if the board moves during cooling. Eutectic or near-eutectic alloys have zero or minimal range.
0–3°C near-eutectic
4–8°C wider
9°C+ wide range
ⓘ The inline bar in the table visualizes each alloy on a common 100–280°C scale. The three vertical reference lines mark the BiSn eutectic (138°C), the standard SAC eutectic (217°C), and the SnCu eutectic (227°C). A tick mark means the alloy is essentially eutectic at that point. A filled bar shows the pasty range width.
02 — Process Columns
Reflow Peak
Recommended peak temperature range for convection reflow. Typically set 15–30°C above liquidus to ensure complete wetting without exceeding component ratings. The upper limit is usually driven by the most temperature-sensitive component on the board, not by the alloy itself.
Wave / Selective
Recommended bath temperature for wave soldering or selective soldering nozzle. Wave baths run hotter than reflow peaks because contact time is short and the board is cooler. N/A means the alloy is not recommended for wave or selective applications, typically because of brittleness, narrow process window, or Pb contamination risk.
03 — Alloy Categories
Standard SAC
Sn-Ag-Cu alloys with silver content between 3.0 and 4.0%. Liquidus around 217–221°C. The mainstream choice for most RoHS assembly. SAC305 is the de facto industry standard. Higher silver improves thermal fatigue life but increases cost.
Low / Ag-Free
Reduced silver or no silver at all. Lower material cost. Liquidus typically 217–228°C depending on composition. Mechanical and thermal cycling performance is generally lower than standard SAC. Good choice for cost-driven consumer lines where long-term thermal fatigue is not a concern.
Low-Temp
Bismuth-tin based alloys with liquidus around 138–141°C. Allows reflow well below 200°C, reducing thermal stress on heat-sensitive components and substrates. Critical risk: any lead contamination in the BOM forms a Bi-Pb ternary eutectic at 96°C, causing field failures. Strict BOM control is mandatory.
High-Rel
Multi-element alloys engineered for extended thermal cycling reliability, typically -40 to +150°C cycling per AEC-Q100 Grade 0. Additions of Bi, Sb, Ni, or other elements strengthen the solder matrix against creep. More expensive and often require supplier-specific process qualification.
04 — Side-by-Side Comparison
Select up to three alloys using the checkboxes on the left of any row. A comparison panel appears below the table showing all key data side by side, including the temperature profile bar drawn on the same scale. Use this to quickly visualise the thermal gap between a standard SAC alloy and a low-temp alternative, or to compare two high-rel options.
ⓘ Expand any row with the arrow on the right for full process notes, typical applications, and a detailed data card without leaving the page.