Homebrew PCBs

Stefan Trethan wrote:
> On Thu, 09 Jun 2005 10:48:43 +0200, Adam Seychell  
> <a_seychell@...> wrote:
> 
> 
>>For your nozzles, see http://www.spray.com  Considering I'm in Australia
>>it only took two weeks to order three nozzles via their Australian
>>representative ( A$10/nozzle). I was surprised to learn that the spray
>>nozzle business is setup for selling small quantities. The factory had
>>to especially make my nozzles because they didn't have them in stock,
>>anywhere.
>>Adam
> 
> 
> What nozzles did you use, i was looking at their page and they have 2 or 3  
> different ones ;-)

That took a while to decide too. The web site lead me to the KYNAR 
VeeJet series:
  http://www.spray.com/catalogs/sg_EtchingRinsing.asp

I was able to find what type of nozzles typically used by spray etch 
machinery manufactures. For fan type nozzles the fan angle is between 
50\ufffd and 80\ufffd. I decided on 65\ufffd angle.
As for the nozzle size, I had to plot a graph showing pressure vs flow 
rate for both the pump and nozzle. Where the two graphs intersect is 
where the operating point is. After some shuffling around of figures , I 
went for three "size 8" nozzles that gives 6.2L/min at pressure of 1.8 
bar  and specific gravity of 1.35, pump voltage 12.0V.




> 
> I will not have time to build a sprayer any time soon, but reason i'm  
> asking about it is that damn bubbler hose has apparently clogged up in the  
> few weeks i wasn't using it. It was all nice and even at fist, but it is a  
> nightmare again now.
> 
> how would it be possible to make a compact sprayer?
> 

nope. compact is not possible. As for simplicity I like the idea from 
Randy Gordon Gilmore, where the only mechanical moving parts is the pump 
itself. Then you might use a full cone nozzle and have the PCB and 
nozzle stationary. But the question is will you gain a lot from this 
method over conventional bubble etching ? I can't answer this question 
because I haven't seen results from this method. It may be possible to 
optimize your bubble etcher. e.g bigger air pump and larger bubbles.