1·镀锡：镀铜后在铜表面再镀上一层锡，大约3mil厚，在下工序中起到抗蚀保护线路的作用。
Tin plating: Immediately after copper plating, a thin layer(0003") of tin is electroplated on the surface of the copper. Tin will act as an etch resist in a future manufacturing process."