A 'PCB' (printed circuit board) negative is printed on a glossy paper using a laser printer.
Printing resolution and toner darkness are set to maximum.
Then, a heating iron (set to maximum temperature or cotton settings) is used to heat and press the glossy paper onto the copper board for a minimum 5 minutes.
This ironing process transfers toner onto the copper board.
The glossy paper will stick to the copper board.
Let cool for 10 minutes.
The copper board (with glossy paper stuck) is soaked in water.
The glossy paper softens and is removed by peeling.
It is let dry.
The copper board now undergoes the etching process.
This is accomplished with soaking the board in Ferric Chloride (acid) solution.
The board is agitated slightly and continuously for 15 minutes.
Ferric Chloride erodes visible copper tracks.
Copper tracks that were protected or covered by the black toner are not affected.
Finally, thinner is applied to rub off the black toner parts.
These remaining visible copper tracks make the 'PCB' to function.
Then, drilling of 1mm holes were done on the board, for mounting of electronic components.
Electronic components are then soldered onto the 'PCB'.
Soldering must be careful.
This is because cold solder joints can be produced if one is not skillful enough in the said act of soldering.
A cold joint is bad because it contains cracks, voids and is brittle.
This is bad for long term usage.
In future, a cold solder joint will most probably cause the component leg attached to it to break, hence disrupting connections or causing a shortage.