Testing and Analysis of Ar Plasma Processed LED at Different Ar Gas Flow Rate and Process Time: Thermal and Surface Verification.

Nonequilibrium plasmas have been extensively investigated for polymer surface treatments in industrial applications. Plasma treatments can change the properties, such as electrical, chemical, tribological, biological, optical, and mechanical, which are easy to scale up to industrial applications. These can be extended to electronic industry. Consequently, light-emitting diode (LED) package was processed using Ar plasma at various flow rates and times. Thermal transient analysis showed reduced total thermal resistance ($R_{{\text {th}}}$) and reduced rise in junction temperature ($T_{J}$) for Ar plasma processed LED compared to the bare LED package data. Among the process parameters considered, 20-sccm flow of Ar gas exhibited better performance with respect to processing times. A noticeable reduction in $T_{J}$ value was recorded ($\Delta T_{J} = 49.2\,\,^{\circ }\text{C}$) for Ar plasma processed LED from that of bare LED. Surface modification through cross linking was assumed by the Ar plasma process and supported to enhance the heat transfer through the modified surface of silicone encapsulation of the LED. In addition, the surface smoothness of silicone was induced by Ar plasma and helped to exhibit efficient heat transfer via convection. Based on the observed results, the Ar plasma process would be an effective postprocessing method for LED package to improve the performance as well as lifetime. [ABSTRACT FROM AUTHOR]