Homebrew PCBs

Hello Markus,


Markus Zingg wrote:
[delete]
> Yes, however the tanks are SEPERATED from each other by a ~1" sized
> gap. That's needed cause the temperature of the baths must be
> controlled individually. That's important here and I mention it to
> give another indication why creating a tank and puting in walls is a
> bad idea here.

That makes perfect sense. Only the baths at room temperature 
can have rinse as part of the "main" tank. Otherwise the 
rinse tanks will have to be separate. I have seen commercial 
counterflow rinsing systems built with one larger tank 
partitioned into equal sections, but I guess that would be 
the obvious way to it.




> 
> Ok, here we go:


Thanks for the detailed description of the process you 
follow. You might remember I am using a different chemistry 
up until the copper electroplating. I'm not really developed 
enough to describe them in detail yet.
I fully understand the importance of making sure every step 
is followed properly. Correct bath temperature, dwell times, 
and rinsing are essential.

> bath #1 is a Cleaner Conditioner that must be run at 65-70 degrees
> celsius (149 - 158 farenheit) the PCB must reside in this bath for 7
> minutes. Thereafter there is a 1 minutes static rinse followed by 1
> minute spray rinse .


65 - 70\ufffdC is a high temperature, does "hobbyglass" material 
become softer at that temperature ? You mentioned that 
working with hobbyglass is easy using hot air tools, so I 
assumed it to be similar to ridged PVC, which I found very 
easy to work with compared to plastics like Plexiglas 
(perspex), polypropylene, polyethylene, polycarbonate.
PVC begins to become soft after 52 to 56\ufffdC, and at 65\ufffd is 
like a very stiff rubbery material and becomes softer as 
temperature rises.

I also found that making wooden jigs helps the building 
plastic tanks. From your photos, it looks like you have done 
very well.


> I rinse the pcb's simply in a water tank, then go to the wall water
> outlet? (don't know the propper english term) and rinse it there for
> another minute. I use a kitchen timer watch to controll the durations
> and take very much care to stay within these times and temperatures. I
> never had a problem yet by doing so.

I can understand why 1 minute is needed for rinsing because 
solution tends to stay on the surface and in holes. You can 
see this when the PCB pulled from an acid solution, rinsed 
and then allowed to dry. Small traces of acid stain the pink 
copper, and it takes a lot more than a 10 seconds of rinsing 
to remove enough acid for no staining to occur.


> 
> I wanted to do something with such a drum tap but haven't found them
> here. Since with my station the tanks simply are standing within the
> grid takeing them out even if they are full is no problem. Once they
> are out they can easily be emptied into normal plastic tanks. In
> general this is definately a very good idea cause some of the fluids
> tend to "vaporize" away if the tanks are not closed - which is hard to
> achive. So, if you can empty the tanks whenever the station is not
> needed this is definately the best solution. Aditionally you will find
> that the stations remains a lot cleaner over time this way.

I always used lids on my tanks, dust and evaporation will 
eventually take their toll. Have you thought of putting a 
hinged lid with some plastic foam underneath to help seal 
off the tanks ?
I'm surprised you cannot find drum taps. They are very cheap 
and sold almost any hardware store here in Australia. The 
cheap ones are about AU$1 wholesale.


>>My aim is to have then entire PCB processing equipment in 
>>the one area so I can make a board without having to run 
>>around over the place. By including rinse tanks I think it 
>>will make the job easier to control. Would you agree ?
> 
> 
> Yes, I agree that having the rinse tanks close is a good idea. I don't
> know though if you manage to have a good spray rinse situation without
> too much hazzle though.

I cannot see why spray rinsing would be that important for 
our operations. Spray might achieve the same result faster, 
or better for removing solids. I don't think is would be 
essential for the  palladium system (super activation) you 
are using. Immersion in a rinse tank and gentle movement of 
the panel for 1 minute should properly rinse. Its mainly 
drilled holes that are more difficult to flush out.
Having recently shopped around for a pump for a spray 
etching machine, its clear that spraying equipment is going 
to cost you :) The Iwaki WD-70RZ I was initially looking at 
can produce 1.5bar at 20L/min but costs AU$600 ($US380), the 
Iwaki WD-30RZ 0.9bar at 9L/min, but I can get for AU$250 
($US170). The lower practical limit for spray nozzles is 
about 0.7 bar so hopefully I can get by with the cheaper pump.
Thanks again for your help, I'll keep you informed when 
things develop.

Adam