Air Gap Corrections in Clamped Stripline in Plane Permittivity Extraction
Air gap corrections eliminate systematic two to six percent dielectric underestimation in clamped stripline tests, preventing finished board impedance failures.
Greenwood-Williamson Model
Contact Mechanics
Statistical modeling of the elastic deformation of rough surfaces under mechanical pressure provides a foundational framework for analyzing electrical contacts. The Greenwood-Williamson model describes how the peaks of a rough surface, called asperities, deform when brought into contact with a flat plane. This model is used to calculate the real contact area and contact resistance of PCB connectors and switches.
Microscopic Deformation
Asperities are modeled as spheres of equal radius with a Gaussian distribution of heights. When the surfaces are pressed together, these micro-contacts deform elastically under light loads before transitioning to plastic deformation as the force increases. The actual area where electrical conduction occurs is much smaller than the apparent geometric area of the contact.
Interface Analysis
Accurate calculations of contact resistance help to prevent signal loss and localized heating in high-power or high-frequency connectors. By analyzing how surface roughness changes under different contact forces, engineers can specify the minimum mating pressure required for reliable electrical connections. This modeling is essential for designing durable tactile switches and board-to-board connectors that must withstand thousands of mating cycles.
It provides a predictive approach that replaces expensive trial-and-error testing of new plating materials and surface finishes in connector manufacturing.