Preheating time
-Must not be too long because the flux will vaporize between 70 to 120°C.
-Due to the also-present solvents which have to vaporize during the soldering process
and which boil at 125° to 250°C the preheating should not be too short.
-The gradient should be around 2.5 K/s.
Liquid time
-This is the time above the melting point of the solder, for solder with lead Sn63Pb = 183°C, for lead-free solder 92Sn3,3Ag4,7Bi = 210 to 215°C.
-The soldering joints have to be melted open and there must be sufficient time for the formation of a meniscus (the ideal time for this is 1 minute).
Cooling time
-Should be minimized in order to avoid the alloy breaking up.
-Due to the components the gradient should not be greater than –6 K/s.
Peak temperature
-Higher temperatures improve the flow behavior of the solder (theoretically >241.5°C).
-The limit is the max. permissible temperature for the components.