Is soldermask considered an insulator for high voltage?

I am designing a power supply circuit that can have voltages up to 100 VDC.
According to IPC-2221 I need 0.6mm spacing for uncoated traces and 0.13mm
spacing for traces with a polymer coating. IPC-2221 doesn't really define
what a polymer coating is and if solder mask is considered one or not. Our
board house uses Taiyo PSR-4000BN soldermask. According to the data sheet
it has a dielectric strength of 500V/mil minimum. Going by that we could
have very small spacing between traces and be ok at 100 VDC. Some boards
that were designed on a previous project did not meet the IPC 0.6mm spacing
but were deemed ok because there was solder mask on the traces. I am not
sure this is a good policy to follow going forward.
Thanks


joel 5 years 3 months 29 days

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Answered byjohndp 5 years 3 months 29 days
Hi Joel,

You should not rely on the IPC specification, instead read the relevant
safety standard(s) for the country(ies) to applicable to your end market
and product class.

Regards
John

On 20/01/2016 19:55, Joel Brown wrote:
I am designing a power supply circuit that can have voltages up to 100 VDC.
According to IPC-2221 I need 0.6mm spacing for uncoated traces and 0.13mm
spacing for traces with a polymer coating. IPC-2221 doesn't really define
what a polymer coating is and if solder mask is considered one or not. Our
board house uses Taiyo PSR-4000BN soldermask. According to the data sheet
it has a dielectric strength of 500V/mil minimum. Going by that we could
have very small spacing between traces and be ok at 100 VDC. Some boards
that were designed on a previous project did not meet the IPC 0.6mm spacing
but were deemed ok because there was solder mask on the traces. I am not
sure this is a good policy to follow going forward.
Thanks