| 摘要: | 國 立 中 央 大 學
化 學 工 程 與 材 料 工 程 學 系
碩 士 論 文
錫鉍/錫銀銅複合銲料之電遷移研究
研 究 生：陳聖揚
指導教授：吳子嘉 博士
中 華 民 國 一一三 年 六 月
中文摘要
現今高功率元件之輸入/輸出埠數量增加，而此技術需仰賴複雜的異質材料組合。異質整合需在迴焊過程中管理熱能分佈，以避免晶片損毀。因此，低溫焊接製程提供了一種減少高溫製程中銲點熱應力的方法。使用錫銀銅（Sn-Ag-Cu）與錫鉍（Sn-Bi）之複合銲料可顯著降低加工溫度，成為有前瞻性的替代方案。
研究中旨在探討複合低溫銲料(SAC305 ball/Sn-56.8Bi-1.0Ag-0.2Cu paste)迴焊接合的電遷移現象。於60°C下通以電流密度（0.8、1.0×10^3A/cm^2），並量測0, 5, 10和20天的電流應力與觀察熱遷移現象。透過觀察通電與加熱後銲料與銅導線之介金屬化合物（IMC）厚度與形貌變化，發現通電後，陰、陽極冷端SAC305/solder界面處IMC將產生粗化現象；熱端SB102/Cu界面處IMC上方受Bi原子堆積，呈塊狀富Bi相抑制生長而無明顯變化。針對此變化，高電流密度又比低電流密度更為顯著。此外，在熱遷移的影響下，Bi由熱端往冷端方向擴散，在熱端IMC上方先粗化，並擴散進入SAC305形成小顆粒分佈。
本研究致力探討SAC305銲球和Sn-56.8Bi-1.0Ag-0.2Cu銲膏之間的界面上Bi顆粒尺寸和分佈，以及複合銲料系統的陰、陽極端之IMC演變。我們將討論熱遷移和應用電流對擴散機制的影響，為複合焊接技術(composite soldering technology)於未來電子製造產業中的可靠度提升進行貢獻。
;Abstract
In modern high-power devices, the growing number of input/output ports demands complex heterogeneous material combinations. Effective thermal management during reflow is crucial to prevent chip damage. Therefore, low-temperature soldering processes provide a promising solution to minimize thermal stress on solder joints, common in high-temperature processes. The utilization of hybrid solders, specifically Sn-Ag-Cu (SAC) and Sn-Bi alloys, can significantly reduce processing temperatures, presenting a feasible alternative.
This study intends to investigate the electromigration phenomena in hybrid low-temperature solder joints (SAC305 ball/Sn-56.8Bi-1.0Ag-0.2Cu paste). samples were subjected to a current density of 0.8 and 1.0×103 A/cm² at 60°C, with current stress measured at intervals of 0, 5, 10, and 20 days to observe thermal migration effects. By examining the changes in the thickness and morphology of intermetallic compounds (IMCs) at the solder/Cu interfaces post-electrification and heating, it was found that IMC coarsening occurred at the SAC305/solder interface on the cathode and anode cold ends. Meanwhile, At the hot end of the SB102/Cu interface, IMC growth was inhibited by the accumulation of Bi atoms, which appeared as blocky Bi-rich phases, showing no significant changes. These changes were more significant under higher current densities compared to lower ones. Furthermore, due to thermal migration, Bi atoms diffused from the hot end towards the cold end, initially leading to the coarsening of Bi above the IMC interface at the hot end. These Bi atoms subsequently dispersed into the SAC305 forming small particles.
This research focuses on the size and distribution of Bi particles at the SAC305 ball and Sn-56.8Bi-1.0Ag-0.2Cu paste interface, as well as the IMC evolution at the cathode and anode ends of the composite solder system. We will discuss the impact of thermal migration and current application on the diffusion mechanisms, contributing to the reliability enhancement of composite soldering technology in future electronic manufacturing industries. |
