Copper deposits preferentially at defects such as cut lines, and rarely deposits in other areas, so large and long elliptical pits appear at the line marks, while in other areas there are small and shallow pits, even uncorroded
Copper is deposited first at defects such as cutting lines, while in other areas it is rarely deposited, so large, long oval pits appear at the online marks, while in other areas they are small, shallow pits that are not even corroded.