Underhood electronic packages are subjected to very high operating temperatures, 125 to 150 ℃ for prolonged period, and most of the plastic encapsulated packages are designed to operate at 55 to 100 ℃ with a designed lower life expectancy of 3 to 5 years, which is much lower than the expected operating range. Electronic market has come up with new materials every day that believed to operate at such high temperatures. In this paper, different underfill materials are subjected to extremely high temperatures and the effect of long time isothermal exposure on oxidation layer and dynamic mechanical properties are investigated. It is very critical to understand the effect of oxidation on the underfill to predict the reliability of the material when exposed to harsh environment. The isothermal aging oxidizes the underfill which can change the mechanical properties of the material significantly. In this paper, the oxidation phenomenon of underfill was studied experimentally by measuring oxidation layer thickness using polarized optical microscope and the dynamic mechanical properties of underfill using DMA (Dynamic Mechanical Analyzer). Four different underfill materials were subjected to three different isothermal exposure which are below, near and above the glass transition temperature of the underfills. The dynamic mechanical viscoelastic properties like storage modulus, loss modulus, tan delta and their respective glass transition temperatures were investigated. Three point bending mode was used in the DMA with an ideal frequency of 1 HZ   operating at 3 ℃/min.


Correlation of Microstructural Evolution With the Dynamic-Mechanical Viscoelastic Properties of Underfill Under Sustained High Temperature Operation

Division / Sponsors: 
Electronic & Photonic Packaging Division (EPPD)

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2020/volume/84041

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