Reflow Soldering - Preheat Zone

Preheat Zone

Maximum slope is a temperature/time relationship that measures how fast the temperature on the printed circuit board changes. The preheat zone is often the lengthiest of the zones and often establishes the ramp-rate. The ramp–up rate is usually somewhere between 1.0 °C and 3.0 °C per second, often falling between 2.0 °C and 3.0 °C (4 °F to 5 °F) per second. If the rate exceeds the maximum slope, damage to components from thermal shock or cracking can occur. Solder paste can also have a spattering effect. The preheat section is where the solvent in the paste begins to evaporate, and if the rise rate (or temperature level) is too low, evaporation of flux volatiles is incomplete.

Read more about this topic:  Reflow Soldering

Famous quotes containing the word zone:

    Just like those other black holes from outer space, Hollywood is postmodern to this extent: it has no center, only a spreading dead zone of exhaustion, inertia, and brilliant decay.
    Arthur Kroker (b. 1945)