Gentleman;

   This board has some restrictions that I would like to share because I am
not familiar with this process and some advice will be helpful.

   1) Prior conformal coating I need wash the board, but there is 6 SMT
photo sensor and more than 20 LED , what cleaning method should I use in
order to not damage or affect performance of this components ?

   2) What level of DRY the board should be before coating, the LED are heat
sensitive and could not be exposed to high temperatures for baking ( more
than 125 degree C ), what baking set up should work ?

  3) What kind of conformal coating should I use for spray application (
acrylic, epoxy,silicone or polyurethane ) , the board environment will be
exposed to 74 degree Celsius in a sunny day ( air temperature inside the
box )

  4) The photo sensor and LED should not be conformal coated, what kind of
masking should I use, for spray coating.

  5) In the back side of the board ( there is no component in this side ) a
heat sink will be attached, and no conformal coating should be applied since
this heat sink will be in contact with a sheet metal, but the heat sink
covers about 30% of area in the bottom side, It is OK to leave the bottom
side without conformal coating since there is no components at this side, or
should I mask the conformal coating and then attach the heat sink after
conformal coating was applied ?

  Thanks for any advice at any question.

Jorge Santana

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