The IPC-4562 document outlines a precise classification system that helps engineers specify the exact type of foil required for their application. The standard categorizes foils based on three primary factors: , Foil Grade , and Foil Thickness (Weight) . Foil Types

In other words: IPC‑4562 governs the raw material . The IPC‑455x series governs the final finish . Both are required for a complete specification: the former for the incoming foil, the latter for the post‑etch treatment.

(High Temperature Elongation or HTE) is widely used for multilayer board cores and laminates to resist cracking during thermal cycles. Thickness Tolerances : The standard allows for a maximum of 10% reduction in the nominal base copper thickness. For instance, a foil may have a minimum acceptable thickness of Surface Treatments