concentrations for etching

[prof. Antonio Guerrieri]

Jeremy wrote:
>I've forgotten the concentrations of sodium hydroxide and ferric chloride
>needed for photoresist removal and etching respectively. Can anyone advise on
>this?
>

Dear Jeremy,

the concentration of ferric chloride hexaidrate should be the following:
about 1 kg/2.5 liters of water, i.e. 1g/2.5 milliliters (from RS catalogue).
Unfortunately, I do not know the concentration for sodium hydroxide.

The concentration is quite high so it is necessary to stirr and wait a
little bit to dissolve all the ferric chloride; hot water can help to
prepare the etching solution.

Be careful in preparing and using such a solution as well as the sodium
hydroxide one.
The etching solution is quite acid while the sodium hydroxide is obviously
a strongly alkaline agent. Both are strong corrosive so be careful.
Some drops on your hands are not really a problems until you wash your
hands as soon as possible, but be careful with your eyes.
That's all.
Best regards,
Antonio Guerrieri