Conformal coating

[stoyanoff]

Greetings! I have a high voltage PCB. And I have a problem with the necessary clearance. I want to use a sensor in SO-8 package, but the distance between the rows of pins in this package is too short. The distance is 5.8mm and the needed clearance is 7.1mm(550V). So I want to add a slot beneath and to cover it with somekind of conformal coating. Can use just acrilic(or silicone if it is better for high voltage protection) coat spray or I need to cover it with rubber like rtv11?
Thanks!

[Rat_Patrol]

Proper spacing rules notwithstanding, I would use epoxy and get it on thick. I don't see how you could sell such a project though. At least in the USA, the first time failure occurred, the lawsuits would start coming in.

[penfold]

Are you intending to sell it?
Where did you get a 7.1mm clearance from? Is it mains? AC or DC?
Conformal coating only strictly reduces your pollution degree for creepage rather than giving you any additional free clearance, potting would be the way to go in you really need to do so for a production

[stoyanoff]

Yes! Potting will be! I`ve changed the construction and I put the problem part on a separated PCB. So now I can cover it with some resin and decrease the polution level. So this will allow me to meet the parameters with lower clearance. And also device could be repaired if it is needed.
Thanks!