Voltage rating / withstand of 0.1mm & 0.2mm prepreg FR4 ...?

[Easy peasy]

Hello All, I imagine it is covered in the UL standards & IEC60950 but before I dig through that is there a well known value, maximum for Vac rating of the above pre-preg... ?

 

[FvM]

The most recent and detailed specifications can be found in IEC 61010-1 2010-06, Annex K. It's the first standard document that discusses horizontal and vertical insulation distances in PCB consistently.

As for minimal prepreg thickness, the document refers to standard test voltages, manufacturer voltage ratings or alternatively actual HiPot measurements and redundancy of insulation layers. E.g. have at least two prepreg layers, each rated for the applied voltage.

 

[Easy peasy]

Thank you - the basic value for FR4 is 39kV/mm which equates to 3900Vac for 0.1mm ( assuming homogeneous, no voids etc )

But the standards modify this ( with good reason ) I will look at IEC 61010-1 2010-06, Annex K, ta.

 

[senilicus]

FR-4 does not specify specific material, but instead a grade of material, as defined by NEMA LI 1-1998 specification.