Homebrew PCBs

roel_cnc wrote:
>  
> 
>>What type of etching solution do you use ? I assume...
> 
> the pcb oscillate about 10 cm 

Does it oscillate side to side movement or is it spinning ?

> 10 nozzles per side makes 20 off it 
> volume off etch is about 25 liters 
> i use the fe3 the brown fluid.

Is your pump a centrifugal or a diaphragm type ?
Do you have a model number for the pump ?
I found a company, www.flojet.com (web site seems to be down at 
the moment). They make a large range of relatively small electric 
diaphragm pumps. These pumps are higher pressure and low volume 
compared to centrifuge type. You probably know that spray nozzles 
need good pressure to work effectively.
Did you consider using proper chemical etching nozzles ?
What is the spray pattern on the nozzles you are using ? Fan or 
cone type ?
I have read that the spray pattern and the positioning of the 
nozzles is critical for uniform etching. Did you experiment with 
different nozzle configurations until you were happy with the 
etching results ?


> the soldermask works the same way - only after developing extra uv 
> cure and after that an oven cure for 60 min at 159 C if you can get 
> the same film (dynachem laminar DM)

Thanks, it seems I should try and get hold of some of this 
soldermask. I wonder if its more expensive than photoresist.
Here is the datasheet for the  laminar DM;
http://www.interflux.pl/wwwpages/products/shipley/laminar-dm.pdf

I guess its not possible for soldermask to be stripped off the 
board after it is fully cured. Methylene chloride paint stripper 
should work, but that will kill the epoxy laminate material too.