In general, PCB Design, the text/ line on the PCB is only placed on the silkscreen layer, whether in front or back. It is also possible to put it in solder mask. On the solder mask, text will show a more sharp, clear and golden color.

Why golden, because the word engraved in the welding layer, underneath is copper foil, so it is the color of gold.

How to achieve golden characters?

To achieve the solder mask has golden characters, indicating that the inscription on the bottom, a copper foil area. Then use PCB to design software, find tools like "fill zone," and then don't have to relate to any pad to form isolated zone in order to show the golden word.