The effect of thermal ageing, fatigue and thermo-mechanical ageing on flexible microelectronic devices is studied and reported from a materials and functional durability perspective. The degradation mechanisms of encapsulant and substrate were both studied. Property changes in encapsulant and substrate materials are analyzed and their relationships in the failure mechanisms of the flexible devices determined. Stiffening of the resin under thermal ageing conditions is associated with delamination in test vehicles, which leads to a loss of functional electrical properties. Degradation was due to the prominence of crosslinking reactions occurring during thermal oxidation at 120 °C. A moderate stiffening of the resin occurs after fatigue stress testing. Whereas this latter stiffening is similarly associated with crosslinking reactions, here, stiffening could not be induced by thermal degradation of the resin, because the stress frequency employed was low. Instead thermo-mechanical coupling occurred in two stages. Under mild conditions, the degradation mechanisms correspond to the combined effect of thermal ageing and fatigue processes. Under harsher thermo-mechanical conditions, the chain-scission mechanisms become more efficient and induce a softening of the resin.

从材料和功能耐久性的角度研究并报道了热老化，疲劳和热机械老化对柔性微电子器件的影响。研究了密封剂和基材的降解机理。分析了密封剂和基板材料的特性变化，并确定了它们在柔性设备的故障机理中的关系。在热老化条件下树脂的硬化与测试载体的分层相关，这导致功能性电性能的损失。降解是由于在120°C的热氧化过程中发生了明显的交联反应。疲劳应力测试后，树脂会适度变硬。后者的硬化类似地与交联反应有关，在这里，树脂的热降解不会引起硬化，因为所采用的应力频率很低。相反，热机械耦合发生在两个阶段。在温和条件下，降解机理与热老化和疲劳过程的综合作用相对应。在更苛刻的热机械条件下，断链机理变得更加有效，并导致树脂软化。