Meaning
Quality assurance procedure for multilayer printed circuit boards that confirms the physical construction matches the design specifications. Stackup validation involves measuring the thickness of individual dielectric layers and copper foils. This step is essential for ensuring that the finished product meets the electrical and mechanical requirements of the system.
Discrepancies here can lead to failures in high-speed signal propagation or physical fitment issues.
Material Consistency
Dielectric constant and loss tangent are verified to ensure they fall within the specified range. During stackup validation, a laboratory might use a cross-section or a time-domain reflectometer to check these properties. Variations in resin content or glass weave can alter the performance of the high-frequency circuits.
Impedance Control
Trace dimensions and their distance from ground planes determine the characteristic impedance of the transmission lines. If stackup validation reveals a layer is too thin, the impedance will be lower than intended. This mismatch causes signal reflections that can corrupt data in a connectivity module.
Manufacturing Tolerance
Variations in the lamination process often lead to slight deviations from the ideal design. By performing stackup validation, a buyer confirms that the supplier has stayed within the agreed-upon limits. The final report provides the necessary data for the certification of the assembly for use in aerospace or medical devices.
