Production Test Methodology to Determine High Frequency Signal Loss of PWB Interconnects

摘要

A new low cost, simple and repeatable production test method for measuring signal loss of printed wiring board (PWB) interconnects is discussed. The method uses Time Domain Reflectometry (TDR) to measure the transition duration of a step pulse through the PWB interconnect to determine the loss. The loss is presented as an "Equivalent 3dB Bandwidth". Signal components with frequencies higher than the Equivalent Bandwidth frequency will incur more than 3 dB of loss passing through the interconnect. The method presents the total interconnect loss and does not describe loss components individually (e.g., dielectric loss and skin effect loss, etc.). This paper describes the specific process of measurement, a metrology capability assessment, and study results demonstrating the method's ability to use the loss measurements to differentiate among PWB materials and structures.