Dielectric materials used for Flexible Copper Clad Laminates (FCCL) for Flexible Printed Circuits (FPC) are typically laminated with copper foils. The peeling strength (typical requirement > 7N/cm) can be measured according to IPC standards or ASTM standards. A detailed discussion of the experience gathered in Solvay's labs on the measurement of this property can be found here, including some considerations on the differences among methods, and some results obtained with Solvay experimental products.