Homebrew PCBs

Markus Zingg wrote:
> 
> Acording to Bungard the etching process of THEIR machines is total
> uniform - as oposed to the (el cheapo) machine I unfortunately first
> bought. I must admitt though that I don't have first hand experience
> with their machines. As soon as time permits - that's currently a bit
> a problem :) - I will take a closer look at this. I may end up buying
> one of those Bungard machines but we will see.
> 


What is the price of the Bungard etching machine ?

> 
> I totaly agree on this one. IMHO serious (fine artwork) kind of PCB's
> can't be etched with those. I had one myself but it's sitting on the
> shelf now.

Yep. :)



> I agree here too, but I think that the rotary principle is suffiently
> good to do this. Again, I can't proofe this at the very moment.

If you end up buying the machine please keep the group informed 
on how well it works. I would be very interested to know.


> 
> 
> This sounds like a good concept (and thanks for the pointer to the
> nozzles).

I actually put the wrong link to the nozzle. It should be
http://www.bete.com/metric/products/pages/nf.htm
At the moment I'm looking at getting a total of 6 x NF10 with 65 
degree fan angle and in 303 stainless steel. Just confirmed the 
price at AUD$10.45
Because its an alkaline etchant I'm allowed to use stainless 
steel. Let me know if you want to know more details on the 
etching chemistry. It is electrically regeneratable.
See http://www.elo-chem.com or google search "elo-chem"


> Please keep us up to date on your progress. Etching is
> really the only step left here that does not work too well at the
> moment. 

Yep, I know what you mean. Once you get everything else working 
great, the quality of the etching step suddenly becomes an issue.

>>I haven't yet found a solution for the pump.
> 
> Yes, I figure this is getting difficult. Have you ever considered
> building the pump also? I was thinking about having a PVC tube formed
> as a circle and then some kind of rotor equiped.....

I know the pump your talking about. I read all the other replies 
too. It appearing that the only pump to use is the magnetic drive 
centrifugal pump. The one I have in mind is the MD-70RZ(T), see;
http://www.iwakiwalchem.com/iwaki/literature/Specsheets/MD5570100.pdf
My uncle is a sales rep for Iwaki pumps, so if he will discount I 
will seriously think about taking the plunge.

According to the graph it should pump 20 L/minute at 1.5 bar. 
Using this information the nozzle type can be calulated.

The challenge now is to design the spray nozzle configuration so 
it etches uniformly. I've been told there is no simple solution 
for working out all the variables. There are things such as the 
number of nozzles, nozzle to nozzle spacing, distance from the 
panel, amount of overlap of the spray pattern, the fan angle, the 
jet incident angle to the panel, the linear sweeping speed of the 
jets, ect. Its one of those things that you just have to play 
with until you get it right. I might have to buy some cheap 
phenolic copper clad to experiment with.

Adam