Homebrew PCBs

Hi Stefan

>well, thanks for the information about rinsing etc.
>
>i would like to have one too, but really don't need.
>also the bungard "starter" chemicals pack is far too expensive for me.
>(i could have them done outdoors too then for this costs)

Hmm, I don't really agree on this one. If the load is good for 4 years
with 100 PCB's a year this makes 400 four layer boards. I don't think
that you get them all outdoors for $650 + Fr4 material cost (which is
just about $20 for a 2 x 6 foot sized piece). 

>i really look forward to hearing of your first results (and pictures!).
>but you should get everything done PERFECTLY before filling.

Yep, I also have to rearange my office here a bit so as the station
gets a good place. 

>i tend to try things before they are ready (remember how i killed the one
>inkjet printer?).
>leaving myself afterwards with a lot more work.

 :-) well, no risk no fun right?

>but on the other hand i also don't believe your station will be perfect
>initially.

What should I say? I better focus on get it done now and present first
results :-)

>try to give it some test runs, with water, but actually heating, pcb in,
>timing, etc...
>also look out for spills with this runs, and get used to handling.

That's what I did yesterday. So far these tests were sucessfull with
the exception of the PCB motor motion voltage regulator getting too
hot at low speed. I'm right now changing the electornics to adjust for
this.

>if you have the possibility to make less sophisticated pcbs (without through
>hole plating) maybe it's also a option for you to fill your station
>gradually, testing stage by stage....

Not needed. The chemicals, baths setup etc. is well tested by my
friend I mentioned and then you also should not forget that the
"compacta 30" from Bungarde operates with the same baths chemicals,
number of baths etc. So unless there is a mechanical issue it should
work just fine.

>i also want to ask you if it is possible for you to give a brief description
>of the plastic welding you used.
>i never did this myself but am very interested.
>you use a temperature controlled hot air gun?

Yes, the gun is from "Steinel". That should be available where you
live. It's the model that comes with  a digital display showing the
temperature. Whenever you change it the display quickly showes the
requested temperature, then changes back to the current one slowly
adjusting it ot the previousely set requested temperature. The
temperature is thereafter held constant. 

>which nozzle diameter do you use, which temperature?
The hobby glass should be processed at 400 degrees celsius. The
diameter I use to bend the glass is one centimeter. In order to bend
it I first draw a line on the glas with a pencil or such. Then I move
the gun along this line about 30 times slowly up and down. The glass
then becomes "soft" and at this point in time it can be easily bent.

There is a special nozzle available to do the plastic welding. The
nozzle allows to feed a plastic stripe into the air stream and is
having some sort of "shoe" at it's end. You can easily feed plastic to
the part of the construction that you heat and - well, it's realy
simillar to welding steel - asuming you did that once in your live :-)

It needs some experimentation to get your hands on it. That said, I
first created a smaller tank just to check how it can be done and also
to get used to the technique. All in all it's a fantastic way of
creating this kind of parts. The gun of course is also useable with
virtually any other thermo plastic material cause it goes up to 600
degrees celsius. Just don't feel tempted to also buy those solder
stripes they sell. The best thing is to cut some parts of 
 the material you intend to use into small stripes and use this one.
There are so many many differnt plastics out there that chances are
low that you get perfect results with thes provided plastic stripes.

As a bonus, I also use the same gun to unsolder SMD and throuhg hole
parts. Works very easy. I will also do some experimentation to see if
the gun could be used to apply solder to the tracks - but hey, let's
first get the through hole plating under control.

>i think the hobby glas is available here also, what did you pay? 

That's the bad part of the story. I bought it at "Hornbach" - which
initially is a German "Baumarkt" that also opened a store here in
Switzerland. A piece sized 125 x 50 centimeter and which is 2mm thick
costs about 15 EUR which IMHO is expensive. However, I wanted to have
the station through visible so as I could detect irregularities in an
early stage and for the tanks it also made sense.

>how sturdy is the plastic, if you have a sheet a4 size and hold it along one
>side how much does it bend?
>would be very nice, thanks.

It bends completely. You can see an example of this if you look at 

http://www.myhome.ch/mzingg/pcbstuff/tps/tps_in_parts.jpg (WARNING,
this picture is huge!!!) on the right lower side of the picture you
can see the heater tube and thermometer holders. They are bent 180
degrees so as they can be hung into the tank side plates.

>have a good night..

You too  :-)

Markus