Mid Loss Laminates That Outrun Their Price Class
Mid-loss laminates paired with low-roughness copper foil match high-cost ultra-low-loss performance at a fraction of the raw panel price.
Copper Elongation
Plastic Deformation Limit
The percentage of stretch a copper foil can withstand before fracturing under tensile strain defines the ductility of the conductive layer in printed circuit boards. High copper elongation values prevent the cracking of traces and plated through-hole walls during thermal cycling. This property is evaluated using standard tensile testing equipment that pulls a copper sample until it breaks.
Substrates with higher values are less susceptible to mechanical failure during thermal stress tests.
Thermal Expansion Integrity
Via barrels expand vertically when the surrounding resin laminate heats up during solder reflow. Choosing foil with high copper elongation ensures that the plated metal stretches with the resin instead of cracking. This metal elasticity is particularly necessary in multi-layer boards where thick substrates generate high vertical expansion forces.
Lamination Selection
Manufacturing methods used to deposit or roll copper foil dictate its inherent grain structure and ductility. For instance, electrodeposited foils must meet specific ductility standards to avoid fractures during the lamination process. Electrodeposited copper foil exhibits lower values than rolled annealed copper foil, which makes it less suitable for dynamic flex environments.
Testing laboratories verify copper elongation using standardized test patterns to confirm that the metal meets IPC standards for the intended application class.