Coating is not to be used as an insulator. There is no guarantee that consistent coating thickness can be controlled meaning the ability to insulate/electrically isolate cannot be controlled.



If the concern is the planar core shorting to the board, ask the supplier to place kapton tape under the core. 



All of our planar transformer drawings call out kapton on the bottom of the core for this very reason.



Ted T



-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner

Sent: Monday, March 20, 2017 11:06 AM

To: [log in to unmask]

Subject: Re: WG: [TN] Screen On Insulation



Torsten,



 Do you know how thick a parylene coating is? My recollection is pretty thin.



 So I checked, very high dielectric strength, thickness typically under 1 mil but it can be built up further with longer processing time.



Any idea wat coating with parylene cost for a small batch of boards?



Thanks,

Bob Kondner





-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Torsten Hagge

Sent: Monday, March 20, 2017 9:17 AM

To: [log in to unmask]

Subject: [TN] WG: [TN] Screen On Insulation



Hi,



cheap solution could be a 1mil kapton tape with the mention risk of air gaps, fine and cost expensive solution parylene HT  coating before placing the ferrite cores... 



Take care 

Torsten







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KRISTRONICS GmbH



Dipl.Ing. (FH) Torsten Hagge

team leader HW development  

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-----Ursprüngliche Nachricht-----

Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Robert Kondner

Gesendet: Freitag, 17. März 2017 21:11

An: [log in to unmask]

Betreff: [TN] Screen On Insulation



Hi,



 



We have a PCB that turns out to require 2500VAC test for 60 seconds and we had some flash over on pads to vias. We also have a planar ferrite transformer with primary windings on one side.



 



Does anyone know of a screen on insulation material that can be used to increase flash over voltages? I would like to get a 2 or 3 mils of material.

My other option is to have a laser cut layer of isolation but that could leave air paths under the material.



 



Any other ideas welcome. 



 



Thanks,



Bob K.