Reflow Soldering Thermal Profiles for PCB Assembly
1 resources tagged with "Thermal Profile"
The thermal profile is the time-temperature curve a PCB passes through during reflow, and getting it right is what separates good joints from cold solder and tombstoning at a Chinese assembly house. SAC305 lead-free paste peaks around 240–250°C, while Sn63Pb37 leaded paste peaks lower at about 215–225°C, each with its own ramp rate and soak zones. J-STD-020 moisture sensitivity levels also drive baking before reflow — skip that on MSL 3+ parts and you get popcorning, so confirm your CM profiles each board and tracks MSL handling.
When you source PCB assembly, a documented and verified reflow profile matters — we check that the factory profiles per board, matches paste type (SAC305 vs Sn63Pb37) to the peak temperature, and bakes moisture-sensitive parts per J-STD-020.
Wiki (1)
FAQ
What peak temperature does lead-free reflow need?
SAC305 lead-free solder typically peaks at 240–250°C, higher than leaded Sn63Pb37 at around 215–225°C. The factory must profile for the specific paste, since over- or under-heating causes defects.
Why does moisture sensitivity matter in reflow?
Moisture-sensitive parts (J-STD-020 MSL 3 and up) absorb humidity and can crack or 'popcorn' during reflow if not baked first. Confirm your assembler tracks MSL and bakes parts before placement.
Related Topics
Have a sourcing project in mind?
Tell us what you need. We respond within 24 hours, including weekends.