近年來隨著功率元件的發展及研發技術提升，產品開始追求高功率密度的元件堆疊。此外，高效能及微縮化的結構將提高元件承載之電流密度，當高密度電流通過銲點時，更容易發生電遷移與焦耳熱的效應，最終可能導致元件失效。因78\78\\]8/此，為了促進功率元件的發展與應用，電流對於接點之影響為提升元件可靠度之必要研究，後續更可作為未來產業界提升元件良率的研究基礎。 本研究開發出在低電流密度且低溫無壓的條件下以電流輔助奈米銅膠燒結方法。實驗結果顯示奈米銅顆粒在經過低電流密度之電流處理後擁有較緊密且連續的微結構、較佳的電性以及較低的孔洞率。本研究討論的模型與文獻中所提之燒結機制不同，除了由電子風力和表面擴散的化學勢作為燒結之驅動力，電流擁塞效應亦是燒結過程中的另一個重要機制。當電流密度僅有102-104 A/cm2時，產生的焦耳熱很少，因此在本系統中焦耳熱對燒結之影響可忽略不計。 本研究亦研究電流對於顆粒間燒結時頸部之成長動力學，藉由建立兩模型來定義頸部生長行為與頸部載子濃度之間的關係。此模型也表明了當電流流經顆粒間的頸部時，頸部的大小將會影響頸部載子濃度、頸部電流密度以及頸部原子擴散通量。此外，相較於傳統燒結模型，此模型更能精準預測及研究電流對顆粒間頸部生長動力學和原子擴散的行為。 ;With the development of high-power devices such as automobiles and 5G telecommunication technology, the performance of high power materials is becoming increasingly demanding. In addition, with the trend toward high efficiency and small form factors in electronic devices, the current density carried by their components is increasing. When high-density current passes through a solder joint, the effect of Joule heating and electromigration may lead to component failure. Therefore, studying the effects of current on these joints is crucial to improve the reliability of power devices and promoting their development and application. Herein, the sintering of Cu nanoparticles (NPs) was explored under low electrical current density at 25°C in the ambient atmosphere. The NPs were printed in a V-groove etch on a silicon wafer and were subjected to stress using an electrical current. Voids in the current-enhanced sintered Cu are considerably less than that without current. Sintering at room temperature avoided interference from Joule heating. Besides surface diffusion along the particles and atomic motion driven by the current, the current crowding effect at the necking region was identified as a critical factor. The influence of electric current on the densification and electrical properties of Cu NPs were investigated. Herein, two mathematical models were proposed to elucidate the underlying sintering mechanism. The results prove that the kinetics of neck growth affects the carrier concentration and total atomic diffusion fluxes in the necking region when the current flows through two NPs. These proposed mathematic models implement traditional sintering mechanisms, providing improved prediction for the enhanced sintering of particles with an electrical current.
