Hello, I have designed a component (which is a antenna bluetooth printed in the board) to be placed in the board. I want to do it in the same way of the next picture:  That is, cooper area, but the gerber can't say this area will have tin (lead free). I mean, I wan't the stencil to have this are routed. How can I keep a copper area visible, and avoid this mark in the stencil? Thanks in advance