Homebrew PCBs

garydeal wrote:
> Hey, has anyone tried using automotive windshield-wiper fluid pumps to 
> spray etchant? In particular, HCl/H2O2 etchant?
> 
> Or maybe taken any apart to see if the fluid path is all-plastic? (no 
> pesky metal to dissolve?)
> 
> Alternatively, is there a suitable small pump available for under say, 
> $40? I wouldn't need all that much volume/minute, and just enough 
> pressure to get a nozzle to spray reasonably well.
> 

The last statement "just enough to get a nozzle to spray reasonably 
well" means you need at least 0.7 bar, or 7 meter head. You are correct 
in that you don't need all that much flow rate. Not sure what pump you 
had in mind but the magnetic drive pumps won't properly spray until you 
get into the $1000+ , 1kW+ range. I suggest you use diaphragm pumps like 
in the spray etcher I made ( see 
http://members.optusnet.com.au/~eseychell/PCB/SprayEtcher/index.html ),
has about 28 meter head (2.8 bar), and still working well after 2 years. 
Shop around for Flowjet brand pumps at caravan sellers.