SMTA International Conference Proceedings

Electrical Performance Evaluation Of High-Frequency Laminates As A Function Of Temperature And Humidity

Author: Brian Wright
Company: Agilent Technologies
Date Published: 10/13/2013   Conference: SMTA International

Abstract: As printed circuit board (PCB) based electrical circuits evolve to become more precise, their electrical performance can change due to environmental conditions. This demands better understanding of PCB laminate electrical properties. As a laminate is exposed to different environmental conditions, such as temperature and humidity, it undergoes electrical performance changes. This paper is part 2 of a 2- part study that compares the electrical performance of different laminates using stripline bandpass filters. Part 1 of this study showed the effect on a high-frequency filter due to temperature changes. Part 2 covers the effects on highfrequency filters due to changes in both temperature and humidity. PCB materials exhibiting stable and consistent electrical performance across operating temperatures and humidity levels will help a circuit maintain precision.

This study measures electrical performance of stripline bandpass filters at 0% and 85% relative humidity (RH). These measurements were initially taken at 25°C and 55°C on a dry board. After 230 days of 85°C / 85% RH, the boards were measured again at 25°C and 55°C. Electrical performance measurements were taken using an Agilent vector network analyzer (VNA), located immediately outside an environmental test chamber. The VNA recorded S-parameters of filters located inside the test chamber. S21 measurements were used to compare filter response, and S11 measurements were used to verify proper connections and PCB manufacturing.

Key Words: 

PCB laminate material, bandpass filter, temperature humidity dependency

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