The standard method of removing moisture from MSL-sensitive SMD components prior to reflow is to bake in an oven for 12 hours or more. Without baking, there is a possibility of popcorning, as the absorbed moisture expands rapidly (as steam) leading to high pressure and mechanical failure. Ranier Dudek explains popcorning here and ISU.edu hosts a failure-mode paper showing actual cases here.

But ovens require a lot of power and time to remove this moisture. Could an alternative be vacuum dessication?

Vacuum pump and dessicating chamber

A vacuum pump would still boil the moisture away, but without the large pressures of steam, correct? And once evacuated, the vessel could sit unpowered for days if needed, saving energy.

Is this viable for SMD components? I see where vacuum storage and packaging is utilized for SMD, but not vacuum dessication itself.

  • \$\begingroup\$ The time is so that the water turns into vapor gently, while a vacuum pump will vaporize it quickly. \$\endgroup\$ – Ignacio Vazquez-Abrams Jul 29 '16 at 16:56
  • 2
    \$\begingroup\$ @IgnacioVazquez-Abrams - that would depend on the pressure, just like baking depends on the temperature. In raising the temperature you are raising the vapor pressure of water a bit above the ambient pressure, lowering the ambient pressure could also achieve the same difference. \$\endgroup\$ – Chris Stratton Jul 29 '16 at 18:46

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