Homebrew PCBs

On 20/03/12 08:42, Philip Pemberton wrote:
> On 19/03/12 21:18, John Anhalt wrote:
>> Hi Phil,
>>
>> This describes the whole process with cupric chloride:
>> http://members.optusnet.com.au/eseychell/PCB/etching_CuCl/index.html
>>
>> I have been using it for several years.  Too much acid leads to
>> undercutting, but the amount of acid is difficult for most DIY'ers to
>> access.  Go by specific gravity and color.
>
> OK, it looks like what I've ended up with is somewhat close to that -- almost
> black liquid, but with green foam (and foam it does: I had to turn the air
> pump right the way down after it foamed over the side of the etch tank and
> onto the concrete floor!)

Foaming too much sounds like you need to dilute with more water (like 50-100%).
Add some HCl for faster etching too.


> There's a slight yellow-brown tint to the green, so there's some FeCl3 left
> in there (or at least some iron-based compound), but I don't think there's
> much...
>
> Etch time with air on one-quarter is around 10 minutes, if even that.
>
> Now if only I could get my hands on dry-film photoresist in quantities less
> than "two bloomin' great heavy reels" (which seems to be Mega's preferred
> sales unit, at a cost of \ufffd100-odd plus VAT)...