隨著半導體產業於人工智慧與物聯網等高需求下的驅動下快速發展，電子元件持續微縮化，使銲點可靠度面臨更嚴峻的挑戰。於現今半導體元件中，用於連接晶片與基板的材料以Sn-3.0Ag-0.5Cu (SAC305) 銲料為主，其具備良好的機械性質、濕潤性及製程相容性，然而隨著輸入/輸出密度提升，其可靠度問題亦逐漸浮現。 本研究以紙質纖維解纖而得之奈米纖維素作為一種具永續性且易分散之強化材料，摻雜入SAC305銲料中以提升其性能。透過熱重分析、穿透式電子顯微鏡、電子探針顯微分析及電子背向散射繞射等分析技術，系統性探討其微結構變化與強化機制。結果顯示，奈米纖維素於迴焊過程中會發生熱解，形成碳質顆粒，並作為 Ag3Sn 介金屬化合物之異質成核點，進而降低銲料過冷度、加速凝固速率，並使其微觀組織轉變為細小之等軸晶結構。當奈米纖維素摻雜比例為 0.05 wt.% 時，可達最佳細化效果，平均晶粒尺寸可由未摻雜之 28.0 µm顯著降低至 14.9 µm，並使剪切強度提升約60%，硬度亦明顯增加。 以熱時效測試加速模擬銲料實際應用環境，將試片真空封管後分別放置於120 °C、150 °C、180 °C之烘箱30天。結果顯示，摻雜奈米纖維素之銲料仍能維持較細小之晶粒與較佳之機械性質。此現象主要歸因於細小且分布均勻之Ag3Sn所產生之 Zener 釘扎效應，有效抑制晶粒成長。進一步於商用印刷電路板進行迴焊，摻雜奈米纖維素不僅可有效降低接合界面孔洞生成，更可提升銲料約10% 之機械性質。本研究證實奈米纖維素，此一具成本效益且環境友善之摻雜材料，可有效細化銲料微結構並顯著提升銲料可靠度，對於未來電子封裝具有高度應用潛力。;With the rapid advancement of the semiconductor industry driven by the increasing demands of artificial intelligence (AI) and Internet of Things (IoT)， electronic components continue to undergo miniaturization， leading to higher reliability requirements for solder joints. Currently， SAC305 solder is widely used for connecting chips and substrates due to its good mechanical properties， wettability， and process compatibility. However， as input/output (I/O) density increases， reliability concerns have gradually emerged. In this study， cellulose nanofibers (CNFs)， derived from paper fibers， were doped into SAC305 solder as a sustainable and well-dispersed reinforcement to enhance its performance. During reflow， CNFs undergo pyrolysis to form carbonaceous particles. These particles act as heterogeneous nucleation sites for Ag3Sn intermetallic compounds (IMCs)， thereby reducing the undercooling of SAC305 solder， accelerating solidification， and refining the microstructure into an equiaxed grain structure. As a result of this grain refinement， an optimal CNF doping of 0.05 wt.% reduced the average grain size from 28.0 µm to 14.9 µm， leading to an approximately 60% increase in shear strength and a notable improvement in hardness. To simulate real-world semiconductor operating conditions， hot storage tests (HTS) were conducted at 120 °C， 150 °C， and 180 °C for 30 days. The results indicate that CNF-reinforced solders retain finer grain structures and superior mechanical properties after HTS. This behavior is primarily attributed to the Zener pinning effect induced by finely and uniformly distributed Ag3Sn particles， which effectively suppress grain growth. Furthermore， reflow tests conducted on commercial printed circuit boards (PCBs) demonstrate that the addition of CNFs effectively reduces void formation and enhances mechanical properties by approximately 10%. This study demonstrates that CNFs， as a cost-effective and environmentally friendly additive， can effectively refine the microstructure and significantly improve the reliability of SAC305 solder， showing strong potential for advanced electronic packaging applications.
