Etch Rate versus Concentration and Temperature: the Numbers
蚀刻速率与浓度、温度的定量关系
标签：蚀刻速率, 三氯化铁, 波美度, 温度系数
三氯化铁蚀铜速率由波美度与温度共同决定：38–42°Bé（约 550–650 g/L）为最佳工作区，35 ℃ 下蚀速约 1 μm/10 s；低于 35°Bé 铁离子不足、速率骤降，高于 45°Bé 粘度过大、离子扩散受阻反而变慢。温度系数近似每升高 10 ℃ 速率翻倍（Arrhenius 经验值），20 ℃ 与 40 ℃ 的蚀时差可达 4 倍。喷淋蚀刻比静浸快 30–50%；溶铜量超过 60 g/L 后蚀液"疲劳"，蚀速下降并转暗绿色，需再生或更换。记录蚀速必须同时标注浓度、温度、搅拌方式三要素。
FeCl3 etch rate is set by Baumé and temperature together: 38–42°Bé (about 550–650 g/L) is the sweet spot, roughly 1 μm per 10 s at 35 °C; below 35°Bé ferric ion runs short and the rate collapses, above 45°Bé viscosity throttles diffusion and it falls again. Temperature roughly doubles the rate per 10 °C rise (empirical Arrhenius), so 20 °C and 40 °C can differ 4× in etch time. Spray beats immersion by 30–50%, and beyond 60 g/L dissolved copper the bath "fatigues"—slower and turning dark green—needing regeneration. Always log rate with concentration, temperature and agitation.