I use a standard office laminator that I bought too many years ago so as
it would make sense to give the exact make and modell. However,
virtually any laminator will do if:
- You can at least modify it so as you can feed it such thick material
like a PCB. Sometimes the housing must be modified to make this possible.
- You can run it at a low enough temperature. Dryfilm laminate needs
somewhere around 100 degree celisius, usually laminators work at higher
temperatures. However, so far every modell I saw used at other places
did not had troubles here.
- You should be able to adjust the pressure applied by the first pair of
rolls. To do so you likely have to open the unit. I can immagine that
there are too cheap ones where that can't be adjusted, but again, those
I saw so far could do this - all of them. My experience is that the
first pair of rolls should almost not apply any pressure, well, just a
very light one. Usually there are screws on the sides of the first roll
pair which screw in feathers that in turn generate the pressure on the
rolls.
I've been told that laminators with rolls that are directly heated work
better, but I don't have one of those and provided the pressure of the
first roll pair is ok, and provided I let it run first long enough to
let it propperly heat up, I have no problems whatsoever with it. Be
warned, with "run it first long enough" I do NOT mean to run it up until
the "ready" light (or whatever indicator it might have) goes on, but to
run it for say 15 or 20 minutes at least. If I'm doing PCBs, I usually
just heat it up, then let it run without interruption therafter up until
I'm done. Mine is having a setting where I can have the heater unit on,
but the rolls don't turn. That's then sufficient for my needs, but
depending on the one you have your mileage may varry. Another finding I
have is that it seems to me that laminating dry film resist becomes
difficult if the pressure of the first roll pair is not even (you can
see this if the PCB is not torn in evenly but turns itself) or if the
room (envireonement) temperature aproaches thirty degrees celsius, or if
the envireonement humidity is fairly high. Since I installed an air
conditioner in my shop these problems are gone though.
HTH
Markus
javaguy11111 schrieb:
>
> You may have mentioned it elsewhere and I did not see it, what are you
> using for the laminator?
>
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>, Markus Zingg <homebrew-pcb@...>
> wrote:
> >
> > Brian,
> >
> > The foil actually only is suposed to serve as a carrier for the dry
> film
> > laminate on both sides of it. The one I use is less than one mil thick,
> > and I suggest to use the thinnest one you can get hold of as long as
> you
> > manage to laminate it which is not all that hard. Just make sure to
> feed
> > your laminator in a direction in which the foil was not originally bent
> > cause otherwise there is the risk that the foil wraps itself around one
> > of the rols of the laminator (been there, had to disassemble/reassemble
> > the laminator :-( ). The extremly thin aluminium foil is also the
> reason
> > why the aluminium is etched away almost instantly (with some impressive
> > bubbling, smoke and even some heat :-) ) when dipping it into Fe3Cl at
> > those spots where the dry film laminate was developped away. You truly
> > don't need any air agitation for this etching process. Dipping is
> > enough. I usually dip it shortly, then rinse and check if still
> > aluminium is there. Somethimes it's necessairy to stick it back into
> the
> > developement bath, then back into the etchant. After two or three
> cycles
> > the stencil will be perfect! The dry film then gives the alluminium at
> > those spots where it's really fine some aditional strenght. I do have a
> > PC microscope but for some reasons it does not work at the moment, so
> > the biggest magnification I can do here are my 8 times magnifying
> > googles and using them I can't tell if there are spots where only
> > dryfilm is present or if the aluminium is still there. The all
> important
> > point though is that even if the aluminium shold be gone, the silk
> > screenig of the solderpaste works without problems for me.
> >
> > I think though that my end resulting stencil is probably not so far
> away
> > from a mylar stencil. I never had one, but I figure structures that
> fine
> > will break easily anyways no matter what material is used. So care must
> > be taken not to bend the stencil sharply. I was however amazed to see
> > how strong it was. The stencil kind of sucked itself to the PCB surface
> > and I've ben able to rub in all directions to truly evenly spread the
> > paste. Raising it thereafter was also no problem and thereafter all
> fine
> > structures at the stencil were still ok. Needless to say that they were
> > also present on the PCB.
> >
> > You may have noted that I took a plastified card of a cardgame as the
> > spatula/squeegee. They are IMHO fairly well suited for the job, can
> even
> > be cleaned thereafter (reused many times) and dirt cheap (just make
> sure
> > you take your sons yugioh (spelling?) or pokemon cards AFTER he grew
> out
> > of it!). Since they are made of cardboard, they do not scratch up the
> > stencil and by bending them more and less you can easily press the
> > solderpaste down to the PCB.
> >
> > The stencil ideally should be 4 mils thick to end up with the propper
> > amount of solder paste on the pads. Since using my method you end up
> > with a stencil of that thickness, subsequent soldering is no problem.
> >
> > I've so far not been able to clean the stencil after use cause all the
> > fluids I tried so far destroyed the dryfilm laminate. It's no
> problem to
> > use the stencil for multiple PCBs while you are at it. Just if the
> paste
> > dries it's (so far) over. However that's really no problem for me cause
> > I a) anyways only produce prototypes (5 pieces of one PCB is a hughe
> > quantity! :-) ) and b) since it only takes 15 minutes to creae a new
> > stencil and since the material costs is close to nothing that doesn't
> > bother me. The time saved compared to hand soldering, and the perfectly
> > looking result way outweight it.
> >
> > As mentioned elsewhere I'm in the process of creating a website with
> > tutorials on how I create my PCBs and how all the equipement I use was
> > made with descriptions and pictures for those intersted in building
> part
> > of it on their own etc. etc. I then also will upload sample pictures of
> > projects done this way.
> >
> > Markus
> >
> > Brian schrieb:
> > >
> > > Never thought of this. Cool idea. You said to use thin foil, when you
> > > apply the paste do you have a problem with the foil between the pads
> > > breaking? and if so does it matter since when it reflows it sucks
> up to
> > > the pads? Also, using thin foil, is there any problem with having
> > > enough solder to make a reliable solder joint? Do you have a
> picture of
> > > the final board?
> > >
> > > Brian
> > >
> > > --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>
> > > <mailto:Homebrew_PCBs%40yahoogroups.com>, Markus Zingg <homebrew-pcb@>
> > > wrote:
> > > >
> > > > Hi group
> > > >
> > > > Under the folowing path in the files section you find a description
> > > on
> > > > how to create your own fine pitch stencils. There you also see
> how to
> > > > apply solder paste with it. The example given is made with one
> of the
> > > > (four layer) PCB's I created here at home.
> > > >
> > > > Files </group/Homebrew_PCBs/files/> > PhotoEtching
> > > > </group/Homebrew_PCBs/files/PhotoEtching/> > solderpaste and stencil
> > > >
> > > > I hope this helps others. Enjoy!
> > > >
> > > > Markus
> > > >
> > >
> > >
> >
>
>