Homebrew PCBs

Markus,

I appreciate your reflexion for copper electroiltic bath.

For me, English is not simple...

Yes, this is a problem to obtain a good result in small tanks and he 
is also many money and techical approch to obtain the same result 
from the profesional PCB industry.

The pro-industry look also for a good stable process in the time for 
big square meter production.

If i have answer your question about dry film.

In industry, after metalisation baths, pre-dip, dip, henhancer etc, 
you have 2 possibility.

#1 Just a difference what you explain, go directly to electrolitic 
copper bats, but just a few minute, just to create the copper hole, 3 
or 5 microns, go to dry film, exposure, developpement and return to 
copper baths for the rest to 17.5 microns.

#2 directly after metalisation bath, no electrolitic copper, go 
directly to dry film, exposur, devellopement, and come in 
electrolitic bath to ceate 17.5 microns deposition.

Why this process,

1, Minder comsomation off copper bath, and important, to etch, the 
etch process is so speed, you have only 17.5 or 22 microns to etch.

If you make copper electrolityc bath for the entire 17.5 microns you 
have base material 17.5 microns(in indudtry only 17.5 microns) + 17.5 
microns from electrolitic deposition, is it 35 microns to etch, 
double etch consomation to make only output your 17.5 microns 
déposition.

This is a stupid action,- make to distroy - .....

And, i think you use base matérial 35 microns + 17.5 microns electro 
deposition.

You obtain 52 or 55 microns copper to etch, so bigger for life time 
of the etch bath.

Other problem occur, etching a big copper cause under-etch problem 
for the fine line, you obtain fine line look a kabalero cigar...

He is preferable to make the copper electro deposition only is 
necessary.

But, to make this process, is necessary make the insolation in 
négative, normaly all dry film make directly negative image from a 
positive film.

Also, your developement bath have a long time life because he 
develope only pad and track an not the inverse.

Normaly, after copper electro deposition, you have also tin or tin-
lead electro deposition, you put out your dry film, and etch with 
amonia solution or persufate, he destroy the copper and not tin or 
tin-lead.

Yes i understand, the is an other way, but it work very very fine.

The air pressure in industry is very important to obtain a oxidation 
in bath copper for long time life.

If you use big amperage per dm2, the problem occur is a non 
equilibration off the brigtner A and B, normaly in the same 
concentration, and is so difficult to make a reequilbration.

You brigtner normaly come in 2 séparate bottle A and B,  or only one 
with A and B in the same concentration.

Yes for the filtration, but not for a long time, residue come from 2 
origin, 1 from anodic film is created on the anode, the anode become 
black, and if you put overamperage, the exess copper oxide go to the 
filter, if you d'ont filter this excess, after a short time, your 
anode d'ont have a good distribution off copper and you make a 
consomation off your copper inside the bath, and the bath dead.

And 2 from the little epoxy fiber from your plate, is necessary put 
out the glass fiber, if not, you obtain inclusion in your drill 
metelalised holle, and the hole have a no good copper deposition.

Patrick





 

--- In Homebrew_PCBs@yahoogroups.com, Markus Zingg <homebrew-pcb@...> 
wrote:
>
> Patrick,
> 
> Your input is highly apreciated. However, I made the experience 
that 
> wiht the very small tanks I use (remember, 4 liters for the copper 
> solution, 2 for the others) it turned out that some shortcuts are 
possible.
> 
> #1 I tried air agitation. It did NOT change ANYTHING to better or 
to 
> worse. So one really can savely omitt this.
> 
> #2 I can run the copper solution at 2.5 t 3 amperes per Dm2 of  
visible 
> copper. Since you mention dry film resist, you must obviousely use 
a 
> different aproach (care to explain it to us?) than I do cause at 
the 
> time I thru plate, I have no laminate on the PCB. The laminate is 
> applied there after. That way, I can reduce the time in this bath 
to 20 
> - 25minutes. Not that I usually care that much though, but I made 
> experiments with less ampères and again, it did not changed the 
quality. 
> Of course, if I go really to 3+ amps what you describe starts to 
happen 
> (mat surface, small nails on the borders etc.).
> 
> #3 the anode bags (polypropylene) is not THAT important for me 
cause I 
> always empty the tanks after use and every now and then filter the 
tank 
> contents while doing so. I fully agree that they are "nice to have" 
> cause they probably could omitt the filtering but it's really easy 
to do 
> so while emptying the tanks versus getting bags that fit the size 
of the 
> home made anodes seems difficult.
> 
> All other statements you made are also along my experience. Again, 
I 
> think above differences have to do with the very much smaller tanks 
I 
> use versus your setup - right?
> 
> Markus
> 
> 
> tsescrl schrieb:
> >
> > Hello,
> >
> > For Anodes copper, very necesary use "PHOSPHORIC COPPER"
> >
> > For me, after 20 year using electrolitic copper bath, is no 
heating,
> > to min 15° centigrade.
> >
> > Attention for the surface of the anodes, anodic surface is 
maximum,
> > but very very maximum 1/2 the surface of the plate per faces.
> >
> > Normaly, use 1.6 Amps per Dm2 of visible copper surface, not the
> > print surface, but only the copper you see after insolation and
> > develop dry film is so little wat you think.
> >
> > Use also 40 minutes electrolitic immersion time and you obtain a 
good
> > result, normaly, 17.5 microns déposition.
> >
> > The déposition is glossy, if you obtain a mat surface, you are 
higt
> > for the ampérage.
> >
> > In first time, with a new bath, attention with the brigtner, not 
add
> > bigger, is necessary a long time before add replenisher brigtner.
> >
> > For brigtner, you add replenisher if you see the external coin are
> > mat.
> >
> > For a new bath, use a brush plate, just a double face plate, no 
dry
> > film, put on the bath, and use 0.2 Amp per dm2 to 2 hours, your 
bath
> > is started, all the impurity is go, and important, your anodes is
> > flashed, normaly hi come black.
> >
> > After 2 our, your plate is very glossy.
> >
> > Also important, put your anodes in a polypropilene sac, al the
> > impurity go not in bath.
> >
> > Very important, if you d'ont use the bath for a long time, put out
> > the anode, and look for the watter évaporation, adjust only with
> > deminéralised watter, only, no chemestery.
> >
> > For anode, you can obtain to "AMPERE" in France, very nice 
matérial,
> > also for tin or tin-lead anode.
> >
> > For electrolityc bath, normaly is also a pump and a filter to make
> > recirculation.
> >
> > Is also very important you have pressure air with a ramp in the
> > bottom off the tank with small drilling holle, the air go to the 
top
> > off the bath, just a little pressure
> >
> > Put this ramp just at the bottom of the plate.
> >
> > Good ammusement, best regards, and d'ont hésitate to ask me.
> >
> > Pleasure
> >
> > Patrick Belgium Europe
> >
> > --- In Homebrew_PCBs@yahoogroups.com 
> > <mailto:Homebrew_PCBs%40yahoogroups.com>, Markus Zingg <homebrew-
pcb@>
> > wrote:
> > >
> > > Hi Suske,
> > >
> > > I obviousely don't care too much from where you get the 
chemistry
> > as
> > > long as it hopefully works out well for you :-). In other 
words, I
> > > apreciate the service Bungard is providing and as such wish 
them a
> > > looong life. Apart from this I'm not related to them in any 
ways. :-
> > )
> > >
> > > For the heaters, I use just dirt cheap regular aquarim heaters. 
The
> > only
> > > thing to watch out here is that they usually don't go up to the
> > > temperature you need. However, they are (usually, check with 
what's
> > > available at your place) built using bimetal switches to switch 
the
> > > power on and off. The ones I found here (really the very 
cheapest
> > ones,
> > > I use 100W heaters) have inside a little plastic part that sits 
on
> > a
> > > fine threaded screw which is what you turn from outside to set 
the
> > > temperature. That plastic part is having a nose to limit
> > the "hottest"
> > > end position. By simply cutting of that nose you can modify the
> > heaters
> > > so as they go up to the requiered 75 degree celsius. There is
> > usually no
> > > problem or security issue involved here apart from the obivous
> > safety
> > > handling of such heaters. The heaters are made for such
> > temperatures.
> > > Those for the aquarium are just limitted so as the average 
aquarium
> > user
> > > does not end up unintentionally boiling the fishes.... :-) Just
> > make
> > > sure you never turn the heaters on if they are not COMPLETELY
> > flodded in
> > > the fluid or else the surrounding glass will instantly break.
> > >
> > > As far as the anodes go I think the phosphor is important to get
> > good
> > > results. I bougth my material from a source here in Switzerland
> > > (Haeuselmann Metalle) which is carrying different alloys of 
copper.
> > One
> > > of them is having a small percentage of phosphor in it. So you 
may
> > shop
> > > around a little up until you find such a source. If you have 
found
> > an
> > > alternative source for the chemistry - why not ask them for a
> > pointer to
> > > annodes? Professionals use copper nuggets in titanium containers
> > which
> > > are then flodded in the copper solution and at least those must 
be
> > > available near you if there are also board houses since this is
> > what
> > > they use. As a last straw, you could use such nuggets, melt them
> > and
> > > found anodes this way. I of course also could buy you the raw
> > material
> > > here at the 1:1 costs of what I pay. However, shipping the ~2KG 
of
> > > material might be a bit costly but feel free to get back to me 
if
> > that's
> > > what you want.
> > >
> > > HTH
> > >
> > > Markus
> > >
> > > _bojan_ schrieb:
> > > >
> > > > Hi Markus,
> > > >
> > > > Thanks a lot for your writing.
> > > >
> > > > Another detail ar fluid heating. Bungard use PTFE plated large
> > area
> > > > heaters. What did you use for fluids heating in tanks?
> > > >
> > > > What about anodes, can I use some copper plate or I must use 
that
> > > > sulphurised copper.
> > > >
> > > > B.T.W. I am on the way to get my chemicals but not from
> > Bungard. ;)
> > > >
> > > > Best regards,
> > > >
> > > > Suske
> > > >
> > > >
> > >
> >
> >
>