Homebrew PCBs

On 18/02/14 17:14, cs6061@... wrote:
>
> This process has been posted before and unfortunately the critical 
> ingredient  of calcium hypophosphite is on the DEA's List I of 
> controlled substances
>

Bugger.  Yes it seems that the calcium hypophosphite is used to make 
copper hypophosphite as the active ingredient, so no real way around it.

It did get me thinking though about copper sulphate, and if maybe the 
simple ascorbic acid precipitation of copper from it could be used to 
make a copper based ink which would be thin enough to flow through holes 
and thick enough to just stick enough to the sides, then bake it off.  
This video is about making a gum arabic carried copper ink by that 
method... http://www.youtube.com/watch?v=9iyRUBvd260

FWIW, the instructable with regards to the calcium hypophosphite is here
http://www.instructables.com/id/Inexpensive-method-of-industrial-level-quality-PCB/step1/Preparing-activator-solution/

And I see using Copper Hypophosphite for activation has also been 
discussed on DP
http://dangerousprototypes.com/2013/05/15/low-cost-pcb-through-hole-plating/