On 17/02/14 07:01, Philip Pemberton wrote:
> On 16/02/14 16:41, Sam Rod wrote:
>>
>>
>> Perhaps you only need more room for the foam? Or reduce the liquid
>> content translating into more room for foam. Put another way if your
>> etchant is working.... The foam control is a small easily solved
>> byproduct. :)
>
> The tank is 1.5 litres, filled with 500ml of etchant, leaving 6-8 inches
> of space from the liquid level to the top of the tank. The foam was
> overflowing the tank after about ten minutes.
>
> I really don't think 500ml of etchant should produce that much foam!
>
> Aeration is an aquarium air-bubbler hose ("air curtain"), a little like
> this one: http://www.ebay.co.uk/itm/181124311130
> The difference is, mine has a right-angle connector on the end instead
> of a straight fitting.
>
> I checked the chemistry a few minutes ago -- bath parameters are:
>
> Acid molarity 1.3 Molar
> Specific gravity ~1.225
>
> I left a board etching earlier this afternoon - after half an hour the
> CuCl had taken a fair bit of copper off but seemed to stop etching as it
> got towards the end. I ended up dumping the board in the ferric chloride
> tank to finish it off.
Foaming is usually a sign the liquid viscosity is too high. Long etching times
are a symptom of that too.
The active ingredient should be diluted 1:1 with water. Add a few percent (like
half a cup) of hydrochloric acid too.
With a setup similar to yours (but working properly), full etch happens in
12mins at room temperature.