銅線使用於打線接合相較於金線有成本低、強度高及導電率高等優勢，但氧化及延展性不足等因素使得銅線於銲線時的可靠度降低，其中，在銲線時產生的斷線亦為使可靠度下降之因素；因此本研究針對ψ=25μm之純銅線，以改變線材之退火條件(150℃~250℃，持溫一小時) ，來探討銅線放電結球前後之機械性質與微觀組織，並針對結球後之拉伸強度進行可靠度分析。

　　實驗結果顯示，退火溫度於200℃上可得到完全退火材，其強度下降，延性上升，組織由單方向細長之晶粒再結晶形成等軸之晶粒。各不同退火條件下之線材經放電產生之結球其球端為柱狀晶組織，球端之頸部由於受熱影響會產生再結晶及組織粗大的現象，且微硬度值及抗拉強度的表現較差，導致結球後之結球拉伸斷裂位置發生於熱影響區間，且拉伸數據的變動範圍較大。

　　韋伯分析結果顯示，各退火條件下之韋伯模數皆屬於m >1之磨耗破壞型，完全退火之線材經放電結球後，其抗拉強度相較於未退火之線材結球會具有較好之可靠度，其中又以200℃退火條件之線材表現最佳。

　　The advantages of copper wire for wire bonding are lower cost, higher strength and electrical conductivity in comparison with gold wire. Oxidation and insufficient ductility of copper wire resulted in low reliability in the copper wire bonding process, and fracture during wire bonding process is also a factor that reduces reliability. In this study, copper wires (ψ=25μm) of different annealing temperature (150~250℃, hold 1hr) had been melted into a ball by the EFO (Electric Flame Off) process and discussed both the mechanism properties and microstructure with wires and FAB (Free Air Ball). Then the UTS of the wires after EFO process had been discussed by reliability analysis.

　　As results as the experiments, fully annealed wires could be obtained as annealing temperature was above 200℃. The elongated grains transformed into equiaxed grains due to recrystallization above 200℃, and the tensile data showed lower strength and higher elongation. The microstructure of copper wire FABs revealed columnar grains. The melting of wire tail resulted in a temperature gradient and caused the variation in properties over the region called the heat-affected zone (HAZ). The HAZ showed the lower hardness and UTS due to the recrystallization and growth of new grains. This result made the fracture occurred in HAZ in tensile test and also caused the distribution of the tensile data showed a larger range.

　　As results as the Weibull analysis, the Weibull modulus under all annealing conditions were wear-out failure mode. UTS of fully annealed wires after EFO process had better reliability than as-drawn wires. And 200℃ was the best condition of annealing.

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