FR4 describes a family of reinforced epoxy materials, not one electrical or thermal specification. A board purchase that says only FR4 leaves several important decisions open.
What to examine in the layout brief
Ask for the actual laminate and prepreg construction, pressed thickness, copper foil and the properties relevant to the project. Review dielectric data at the intended assessment conditions and distinguish glass-transition measurements from service-temperature evidence.
What belongs in the release record
Record the permitted substitutions in the fabrication note. Use the Circuit Edge material selector to organize the comparison, then agree the exact construction with the supplier.
Discuss this with Circuit Edge
Send the current schematic and board revision, mechanical constraints, intended construction and the question you need resolved. Circuit Edge Technologies provides PCB layout, hardware-design support, manufacturing review and practical training from Sector 70, IMT Faridabad. A useful enquiry separates the supplied inputs from decisions that still need agreement, so the scope of the review stays clear.
Open the related Circuit Edge workspace → Discuss your board
Numerical limits and acceptance criteria must come from the actual component documentation, supplier agreement and applicable standards. No proprietary standard tables are reproduced.