Homebrew PCBs

Kamal Shankar wrote:
> 
> 
> I would be interested in getting a good idea of what
> are the etchants being used.
> 
> AFAIK, they are :
> 
> 1. Hot FeCl3
> 2. Muriatic Acid + Hydrogen Peroxide
> 3. Copper chloride
> 
> And I got that hopefully, in order of popularity.
> 
> If all these work, the 2nd choice seems to be easier
> to get and use; so why is the first so popular.
> I myself use it, and the reason being people I know
> who do it professionally use it too ?
> 
> What's the reason? Financial? (The 2nd choice is a
> little bit cheaper than the first) Speed? Ease of
> storage?
> 

As you noticed, there are a number of etchants used by hobbyists.  That 
shows there are exists pros and cons with all of them and each suit 
users differently. FeCl3 has the advantage of indefinite shelf life 
(H2O2 decomposes over time), quick (but not the quickest), and easily to 
use (no mixing or preparation) and wide availability.

I use alkaline ammonia chloride etchant because I etch with 
electroplated tin as the etch resists, and all acid etchants attack tin. 
This etchant is very rare among hobbyists because it really needs spray 
etcher or sealed chamber to operate due to ammonia fumes. It also needs 
complicated chemical analysis to make sure it stays working.