NIST Develops Test on Circuit Board Materials Temperature Sensitivity
June 16, 2006
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Electrical circuits may act differently in Arizona than they do in Alaska, with varying climates and temperatures potentially affecting the performance of computers and other electronics, but a new technique from the National Institute of Standards and Technology (NIST) can now identify and quantify an important cause of this temperature sensitivity.
Researchers at NIST and DuPont Electronic Technologies demonstrated a nondestructive method for measuring how temperature affects the electrical properties of three common circuit board materials - ceramic, polymer and glass. The work provides manufacturers with an accurate technique for measuring high-frequency electrical properties of substrates without cutting up the material, thereby enabling faster, less expensive and easier testing, as well as a tool for designing circuits and substrates with improved performance.
NIST has been working with ceramic and printed-wiring board manufacturers for five years to develop the technique. The method was previously used to measure changes in electrical properties while substrates were subjected to different electromagnetic frequencies. Experts said the work is important to the electronics industry because the performance of electrical circuits depends in part on the electrical properties of the substrate.
The apparatus used in the experiments, a split-cylinder resonator, was originally designed elsewhere, but NIST developed a mathematical model - now approved as an industry standard - that improves its accuracy and extends its frequency range.
A thin piece of substrate was placed between two halves of a cylindrical cavity - smaller than a coffee mug - inside an environmental chamber. A computer analyzed the changes in the microwave-range resonant frequency as the chamber temperature changed from -50 to 100 degrees Celsius (-58 to 212 degrees Fahrenheit). As the temperature rose, an important electrical property called loss tangent (a measure of electrical losses in an insulating material) fell in glass, generally increased in the organic substrate and remained stable in one type of ceramic while rising slightly in another.
Source: National Institute of Standards and Technology (NIST).