此實驗定量研究低溫無鉛銲料合金中銻（Sb）添加量（0至2.2 wt%），以及相異處理條件之銅基板在110°C高溫熱儲存（0至720小時）微觀組織演變、宏觀材料力學性能與界金屬間化合物生長動力學特徵。EBSD統計證實，添加2.2 wt% 銻能引發成分過冷，使初始銲料平均晶粒顯著細化至2.463微米。在熱儲存初期（1000小時），過飽和基體內富鉍（Bi）相的爆發性析出產生彌散強化，使2.2 wt% Sb銲料的抗拉強度與硬度分別達到峰值的108.62 MPa與25.63 Hv；時效中後期（1500至2000小時），富鉍相受奧斯瓦爾德熟化驅動過度粗化至5.913微米，導致強度與硬度增長停滯，但伸長率系統性回升。
在銅基板與界面反應方面，原始銅板具備滾軋織構與20.71微米的粗大晶粒；經20 g/L硫酸處理後，基板內部引入了18.2%的未再結晶高應變胞區；而經80 g/L硫酸添加明膠電鍍處理之銅基板，則展現出隨機取向的多晶特徵與1.73微米的超細晶組織，並儲存了高密度的幾何差排缺陷。高溫熱儲存720小時後，所有組別均由單一層狀Cu6Sn5 演變為Cu6Sn5與Cu3Sn 雙層結構。其中，電鍍銅基板因具備超高密度的大角度晶界（HAGB）與位錯通道，提供原子擴散極佳的低活化能路徑，使720小時的雙層 IMC 厚度達到全系列最高的24.97微米與35.06微米。
透過經典核心成長方程式 (t)=x_0+k．t^n進行動力學擬合，原始銅板組別的成長速率常數 k 為0.345，時間指數 n 為0.4；而經硫酸處理與電鍍處理組別的 k 值分別大幅提升至5.8與12.99，且其時間指數 n 分別下降至0.24與0.22。此擬合參數定量證實，經硫酸與電鍍處理的銅基板體系，其固態時效過程主導為晶界擴散機制。基板微觀組織的細化與大角度晶界密度的增加，顯著提升了成長速率常數 k 並加速界面 IMC 的粗化。本研究數據為低溫無鉛銲點在高溫長期服役環境下的可靠度規劃提供了核心理論。

This study quantitatively investigates the microstructural evolution, macroscopic mechanical properties, and growth kinetics of interfacial intermetallic compounds (IMCs) in low-temperature lead-free solder alloys with varying antimony (Sb) additions (0 to 2.2 wt.%) on copper (Cu) substrates with different surface treatments during high-temperature thermal storage at 110°C (0 to 720 h). Electron backscatter diffraction (EBSD) analysis confirms that the addition of 2.2 wt.% Sb induces constitutional supercooling, significantly refining the average initial grain size of the solder to 2.463μm. During the initial stage of thermal storage (1000 h), the explosive precipitation of the bismuth-rich (Bi-rich) phase within the supersaturated matrix provides dispersion strengthening, driving the ultimate tensile strength and Vickers hardness of the 2.2 wt.% Sb solder to peak values of 108.62 MPa and 25.63 Hv, respectively. In the mid-to-late stages of aging (1500 to 2000 h), driven by Ostwald ripening, the Bi-rich phase undergoes excessive coarsening to 5.913 μm, which halts further increases in strength and hardness but leads to a systematic recovery in elongation.
Regarding the Cu substrate and interfacial reactions, the as-received Cu plate exhibits a rolling texture with a coarse grain size of 20.71 μm. Surface treatment with 20 g/L H2SO4 introduces 18.2% unrecrystallized high-strain cell structures into the substrate interior, whereas electroplated Cu treated with 80 g/L H2SO4 and gelatin exhibits a randomly oriented polycrystalline nature, an ultra-fine grain structure of 1.73 μm, and a high density of geometrically necessary dislocations (GNDs). After thermal storage at 110°C for 720 h, the interfacial IMC layer in all groups evolves from a single planar Cu6Sn5 structure into a Cu6Sn5 and Cu3Sn bilayer structure. Specifically, the electroplated Cu substrate, owing to its ultra-high density of high-angle grain boundaries (HAGBs) and dislocation channels, provides a low-activation-energy path for atomic diffusion, yielding the highest bilayer IMC thicknesses of 24.97 μm and 35.06 μm at 720 h across all series.
Kinetic fitting via the classical core growth equation (t)=x_0+k．t^n indicates that the growth rate constant k and time exponent n for the as-received Cu plate group are 0.345 and 0.4, respectively. In contrast, the k values for the H2SO4 treated and electroplated groups significantly increase to 5.8 and 12.99, while their time exponents n drop to 0.24 and 0.22, respectively. These fitted parameters quantitatively demonstrate that the solid-state aging process of the H2SO4 treated and electroplated Cu substrate systems is predominantly controlled by a grain boundary diffusion mechanism. The refinement of the substrate microstructure and the increased density of HAGBs substantially enhance the growth rate constant k and accelerate interfacial IMC coarsening. The experimental and kinetic data established in this study provide a fundamental theoretical basis for the reliability design of low-temperature lead-free solder joints under long-term high-temperature service environments.

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