本研究主要目的為探討無氧銅薄板之雷射可銲性及銲接製程窗口(Welding Process Window)。研究將無氧銅/無氧銅鍍鎳/無氧銅鍍錫三種薄板試件置於厚度0.2mm冷軋鋼板(SPCC)上方，以雷射進行疊合點銲(Lap-Joint Welding)。接合後藉由銲道機械性質測試及金相組織分析，以評估不同材料及不同雷射銲接參數下銲點之導電度、強度以及金相微結構組織特性，並透過EPR電化學實驗分析銲點於一般環境下之抗腐蝕能力。最後尋找出最佳之銲接參數以作為未來雷射銲接銅薄板之銲接製程窗口。
研究結果顯示，母材方面由於無氧銅鍍錫擁有最高雷射吸收率，且在銲接初期將於熔融區形成熔點較低之銅錫合金，使熱可有效往下傳遞至SPCC，因此在三種銅料中具有最佳雷射可銲性。製程參數正離焦距離增加將使熔融區域高度往上提升，進而使銲接窗口及銲點面積逐漸擴大，且在正離焦9mm及10mm時將有最佳銲接效果。
研究分析結果顯示，在製程參數正離焦9mm、脈寬10ms、峰值功率10kW、罩吹氣體(Ar)流速10L/min時將有最大銲點直徑955um，測試銲點拉力平均值最大可達74.3N，電阻值為最小0.217 mΩ，但由於其擴散層中鐵離子含量達38%，銲道容易形成選擇性腐蝕，造成抗腐蝕性較不佳。

This study investigated the laser weldability and welding process window of three different copper sheets: the oxygen-free copper (OFC), OFC coated with nickel or OFC coated with tin, on the SPCC (thickness 0.2mm) where Lap-Joint welding by laser were performed. The mechanical properties test and microstructure analysis of the welding joint were used to examine the degree of conductivity, strength and microstructure characteristics in different materials and parameters. The welding ability of corrosion resistance at general environmental was analyzed by electrochemical test. Finally, the optimum welding process window as laser welding of copper sheet would be obtained.
As the results of the experiment, the base material – OFC coated with tin had the maximum laser absorptivity. At the beginning of welding, it would form the copper-tin alloy with low melting point at the weld fusion zone, so the heat could be effectively passed down to SPCC. Thus, OFC coated with tin would achieve satisfactory laser weldability among three different copper sheets. The molten zone was raised up with the increasing defocus distance to expand the process window and spot area gradually. There were optimum effect of welding when the defocuses distance were at 9mm and 10mm.
As the analysis of the experiment, there was the maximum welding diameter 955um under defocused 9mm, pulse width 10ms, peak power 10kW, shielding gas (Ar) flow rate 10L/min, which would have the maximum tensile force of 74.3N and minimum resistance of 0.217 mΩ. But there was poor corrosion resistance due to the content of iron ions with 38% at diffusion layer which would cause the selective corrosion easily.

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