I see a person print his circuit diagram to paper, than he stick tightly that paper in the copper board and iron it, after that, he soak the copper board (and paper on it) in water and rub away paper, than leave in the copper board the circuit diagram with printed lines, then he soak that board again into a solution (don't know what it is) for a while, and when get it out, you see the printed lines are replaced by copper lines ?

Could you explain for me the chemistry events in this process ?

Thanks !!!

printed on the paper is an "Ink", an ink that when heated will melt and transfer onto the raw copper plating on the circuit board sheet (probably fiberglass).

this ink is also Not affected by the solution that dissolves the copper, and so it stays where it is and protects the copper underneath it.

 

another solvent will then remove this "ink" to leave the pure copper tracks that you see.

 

later the nodes will have small drill holes made in them, the electronic parts inserted into them, and then soldered into place.

when the excess component leads are all cut off to the correct length, a Laquer is then applied and hopefull the product is in good working order

In general, there are two kinds of masks - positive or negative. Depending on the specific etch processes, you can etch the mask or what isn't covered by the mask.

well thanks !!!

And do you think that we can make two sided PCB at home ?