Breakdown Voltage of FR-4

Dear JLCPCB Team,

I hope this message finds you well.

I am currently working on a project that requires specific dielectric properties, and I would like to request the breakdown voltage rating for the standard FR4 material used in your PCBs. Could you please provide detailed specifications, including the breakdown voltage per unit thickness (e.g., kV/mm), or any relevant datasheet available?

Your assistance would be greatly appreciated.

Best regards,

SRB