Ok Markus,
All i have describe is an industry process but perhaps you can apply
somme partial to your labo for electronic developement.
No, we d'ont use two films, only one before big copper electro
deposition.
To make trough hole in a Double face PCB, in a first time you drill
in PCB plate with 17.5 microns copper on the 2 faces.
You go to chemical process,
Permanganate (desmear),
Pre-dip
Dip
Henhancer
Micro-etch
A this moment, you dry the plate, brushing, an you put the dry film
on the plate with laminator.
Normaly, your dry film is an negative photo emulsion.
You make thes UV exposition + developpement.
Normaly, at your pad and your track you can see the base copper.
(negative)and on hal the plate you have the dry film; inverse at you
obtain at this.
You make the copper electro deposition,
The electro copper go inside the hole and on the pad and the track,
not on the rest off the plate, the dry film protect.
You continue in an other tank with an other bath Fluoboric acid + Tin
or Tin-lead anode.
You make also an electro deposition, 10 or 12 minutes at 1.4 Amp Dm2
After, you disolve the dry film, you obtain:
The base copper 17.5 micron, only on the pad and track, copper
deposition from you first bath,+- 17.5 microm copper + tin or tin-
lead deposition.
The problem is for etching, Fe3Cl is not a good way, hi etch all, but
if you use amonium persulfate, you etch the copper and not the tin or
tin lead on the pad + trace + holes.
After etching, you put special oil ont the Plate, and make a fusion
of the tin or tin-lead, you can make with a heat gun, way not.
Your PCB is finish with Tin or tin-lead, and you have a nice aspect,
very glossy for tin or tin-lead.
The principe for electro deposition for Tin or Tin-lead is the same
off copper, but an other bath and other anode.
Bath is: Fluoboric acid + watter + Tin fluoborate or + Lead
fluaborate + brigtner, thats all.
Attention, some dangerous, his etch this glass, and etch the brill.
The coposition for copper bath is Sulfuric acid + watter + copper
sulfate + brigner, thats all.
For gold immersion, this is an other system very very hight price
After etching, you disolve the tin or tin lead, put the solder mask,
green ink, and continue to an chemical imersion line , normaly 8 or
10 different bath, Micro etching to obtain a pur copper, a new dip, a
new henhancer, a gold preparation, the gold ionic transfer, a hardner
and big rinc watter, the gold ionic transfer is an cyanate bath, very
dangerous, not drink...
This is so so expensive, and the gold are not gold, but an
association with a little gold and an other, i d'ont remeber, it come
after. The gold is price hight an not so hard.
Good reflexion for your trough hole plating line and congratulation,
because is not simple to process little serias PCB.
Patrick
--- In
Homebrew_PCBs@yahoogroups.com, Markus Zingg <homebrew-pcb@...>
wrote:
>
> Patrick,
>
> First off, your english is better than my french :-) Many thanks
for
> taking the effort!
>
> Thanks for the insight here. I'm lucky enough to have 17.5micron
base
> material, but you are right that I of course end up having to etch
away
> 35microns with my aproach.
>
> The amperage I use is based on recommendations of the bath
manufacturer
> (which seems to be J-Chem btw.). I obviousely only have experience
based
> on my real small setup - I never worked in the PCB industry and as
such
> followed the instructions given to me to the letter. :-) I could of
> course run the board with a smaller ampereage. So far I did not
> experienced drawbacks from not doing so, but its only lately that I
have
> a somewhat higher demand for boards.
>
> Interesting aproach you describe really. I have to try this out.
> However, what makes me wonder a bit - I figure you then have to use
two
> films right? I may misunderstand the process thoug.... But if I get
that
> right, I would have to build up copper in the holes (obviousely)
and
> where the traces otherwise are.If you use two film sets, I'm not
sure if
> that would pay off here cause makeing the films is one of the more
> expensive parts here. In other words, using the copper bath and
etchant
> (Fe3Cl in my case) a bit more seems cheaper in the end. Still, very
> interesting and I may will try this out. Could be that it would pay
off
> especially with very fine traces. I sucessfully made 5 mil traces
> already (did not had a board that requiered 4 mil which is from
what I
> understand also the end of the rope in the industry) but making
them in
> fact is a bit demanding in terms of etching (etch process is often
> stopped to check, bord must be repositioned etc. something I of
course
> can do in my "one off" kind of aproach).
>
> Could you tell me a bit more about how you do the tin electro
deposition
> process? I actually use a kind of tin paste that I apply to the
board
> and then use a heat gun... Probably a bit crude, but it works. I'm
> however intersted to hear what alternatives I might would have. Do
you
> think it would be feasable to make gold imersion, and if so, how
would
> that have to be done?
>
> Markus
>
> tsescrl schrieb:
> >
> > 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
> > <mailto:Homebrew_PCBs%40yahoogroups.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>
> > > > <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
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>