SMTA International Conference Proceedings

Moisture Effects in Common Solderable RF Connector Dielectrics Part II: Characterization of Damage Threshold Moisture Level for Moisture/Reflow Sensitive Polymers

Author: Jeffrey Marcus Jennings
Company: Harris Corporation
Date Published: 9/17/2017   Conference: SMTA International

Seika Machinery, Inc.

Abstract: Control of moisture exposure and proper handling, packaging, and storage during the surface mount assembly process are essential to prevent moisture-related damage from occurring during soldering operations. In Part I of this study, an evaluation of a new category of materials was performed revealing moisture/reflow sensitivity in select types of polymeric materials used as radio frequency dielectrics in solderable surface mount device connectors. The previous work presented estimates for floor life (as defined in IPC/JEDEC J-STD-033) based on conservatively assumed maximum moisture content thresholds below which these materials should readily survive the solder reflow process. The current work will subject moisturesensitive material samples of varying moisture content to thermal stress testing to establish more accurate maximum acceptable moisture contents (MAMC). Thermal stress testing will be performed for worst case wave soldering conditions as described in J-STD-020 using a TA Instruments Q400 thermal mechanical analysis (TMA) system to simulate the soldering thermal environment, as demonstrated in Part I of the study. Select printed wiring board (PWB) materials will also be subjected to TMAsimulated Pb-free assembly thermal stress testing to assess the method’s capability for characterizing more complex materials with well-established MAMC values. Moisturerelated damage is evaluated by visual inspection and interpretation of in situ sample length measurements at temperature collected by the TMA. In addition, alternate drying and storage conditions for the moisture/reflow sensitive materials will be evaluated and compared with default bake conditions specified in IPC/JEDEC J-STD-033.

Key Words: 

moisture effects material characterization, moisture/reflow sensitivity, RF connector dielectrics, maximum acceptable moisture contents, MAMC

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