Homebrew PCBs

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

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, 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
>

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>, 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
> >
>
>

You may have mentioned it elsewhere and I did not see it, what are you
using for the laminator?


--- In Homebrew_PCBs@yahoogroups.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>, 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
> > >
> >
> >
>

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
> > > >
> > >
> > >
> >
>
>

--- In Homebrew_PCBs@yahoogroups.com, "Brian" <blue_eagle74@...> wrote:
>
> Never thought of this. Cool idea. You said to use thin foil.

I've been doing something similar, but using brass shim stock.  I
started with 5 mil but that was getting too much solder paste on the
fine-pitch stuff, and also I was having some sideways etching problems.
I changed to .003" shim stock, and have had great results so far.  I
clean the shim stock with fine sandpaper on both sides to remove oil
or plastic preservative coatings.  I laminate both sides of the shim
with DuPont Riston etch resist dry film.  I then expose with aligned
mirror-image films and etch like a circuit board in a Kepro spray
etcher.  This has a heater that brings the etchant temperature to 35 -
40 C.  I have had a little problem in that the board holder in the
etcher is designed to hold rigid things like PC boards, and the .003"
shim stock is too flexible, so I will have to provide a frame next
time I do it.  But, the results have been quite good.  I have done
down to 0.5mm pitch chips.  I had some breakdown of the "bars" between
adjacent apertures with the .005" shim, but it is working great on the
.003" material.

Jon

Jon Elson wrote:
> 
> 
> --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "Brian" <blue_eagle74@...> wrote:
>  >
>  > Never thought of this. Cool idea. You said to use thin foil.
> 
> I've been doing something similar, but using brass shim stock. I
> started with 5 mil but that was getting too much solder paste on the
> fine-pitch stuff, and also I was having some sideways etching problems.
> I changed to .003" shim stock, and have had great results so far. I
> clean the shim stock with fine sandpaper on both sides to remove oil
> or plastic preservative coatings. I laminate both sides of the shim
> with DuPont Riston etch resist dry film. I then expose with aligned
> mirror-image films and etch like a circuit board in a Kepro spray
> etcher. This has a heater that brings the etchant temperature to 35 -
> 40 C. I have had a little problem in that the board holder in the
> etcher is designed to hold rigid things like PC boards, and the .003"
> shim stock is too flexible, so I will have to provide a frame next
> time I do it. But, the results have been quite good. I have done
> down to 0.5mm pitch chips. I had some breakdown of the "bars" between
> adjacent apertures with the .005" shim, but it is working great on the
> .003" material.
> 
> Jon


I had attempt at stencils. The main difference between PCB and stencil 
your trying to etch 100um~150um instead of 35um. Any professional who 
etches stencils, will double side etch. I was trying to etch for QFN 
packages with 0.5mm pitch, and could not get the required accuracy. All 
the other component pads were usable. It was only this particular IC 
that caused me problems. Major factors affecting the accuracy of the 
stencil were limitation on my inkjet printer resolution and etch 
undercut. I tried compensating for etch undercut and even tried double 
sided etch, but failed to get consistent apertures for the 0.5mm pitch 
pads. In the end I paid $180 for a brass stencil , which I mounted to my 
own frame.
For parts like 0603, 0402 , 0.65mm pitch TQFP, then I think home brew 
stencil etching is quite feasible.

I was new to stencils and solder past printing so maybe someone can 
prove me wrong.

Adam Seychell <a_seychell@...> writes:

> I was trying to etch for QFN packages with 0.5mm pitch, and could
> not get the required accuracy.

I've not had good luck with those; I now use 2mil brass for 0.5mm
pitch to reduce the problems.  I can usually get good enough for 95%
of the pins, which is good enough for DIY I suppose.

> and etch undercut.

http://www.delorie.com/pcb/brass/20070220-60-top.jpg

Adam,

Long time since. Nice to see you are still around :-)

If you look at the example picture I uploaded, you can see the pads of 
an LQFP164 with a heat absorbing pad in it's center. Thats a 0.4mm pitch 
part. It worked out well. As for the printer, I fully agree that here it 
really depends. If with "inkjet" you refer to a HP inkjet you are 
definately out of luck. I use an Epson Stylus C62 which was and is well 
known for it's exceptional acuracy and deep black covering miles away 
from what other inkjet printers can do when specifying "premium glossy 
paper". I heard that the Cannon Pixma 3500 which is a more recent model 
performs as well. Most people refuse to belive that there are such great 
differences between printers, but there truly are. All I can say is that 
I tried several inkjets back then, and the Epson outperformed the others 
to such a great deal that I rushed out and bought two of them to have a 
backup should the first one break!

You may want to give a Cannon Pixma 3500 a shot. It's a fairly cheap unit.

Markus

> I had attempt at stencils. The main difference between PCB and stencil
> your trying to etch 100um~150um instead of 35um. Any professional who
> etches stencils, will double side etch. I was trying to etch for QFN
> packages with 0.5mm pitch, and could not get the required accuracy. All
> the other component pads were usable. It was only this particular IC
> that caused me problems. Major factors affecting the accuracy of the
> stencil were limitation on my inkjet printer resolution and etch
> undercut. I tried compensating for etch undercut and even tried double
> sided etch, but failed to get consistent apertures for the 0.5mm pitch
> pads. In the end I paid $180 for a brass stencil , which I mounted to my
> own frame.
> For parts like 0603, 0402 , 0.65mm pitch TQFP, then I think home brew
> stencil etching is quite feasible.
>
> I was new to stencils and solder past printing so maybe someone can
> prove me wrong.
>
>

Thanks for letting us know about printers. I currently use a Cannon 
Pixma MP810 (the all in ones). I have not compared it to any other 
printer other than my previous printers. Thats because I need to really 
take close look at the prints, and try different settings, and you can't 
do that in shops.
The darkness is very good , but the line edge jaggedness and resolution 
is somewhat poor among all inkjet printers I've looked at. I've don't 
believe black sharpness or ink drop placement accuracy could be a lot 
better in future printers, simply because its already exceptional for 
normal reading and text. For PCB artwork use, we are pushing the limits.

BTW, the defects I'm talking about are only visible when looking under a 
microscope.

Markus Zingg wrote:

> 
> 
> Adam,
> 
> Long time since. Nice to see you are still around :-)
> 
> If you look at the example picture I uploaded, you can see the pads of
> an LQFP164 with a heat absorbing pad in it's center. Thats a 0.4mm pitch
> part. It worked out well. As for the printer, I fully agree that here it
> really depends. If with "inkjet" you refer to a HP inkjet you are
> definately out of luck. I use an Epson Stylus C62 which was and is well
> known for it's exceptional acuracy and deep black covering miles away
> from what other inkjet printers can do when specifying "premium glossy
> paper". I heard that the Cannon Pixma 3500 which is a more recent model
> performs as well. Most people refuse to belive that there are such great
> differences between printers, but there truly are. All I can say is that
> I tried several inkjets back then, and the Epson outperformed the others
> to such a great deal that I rushed out and bought two of them to have a
> backup should the first one break!
> 
> You may want to give a Cannon Pixma 3500 a shot. It's a fairly cheap unit.
> 
> Markus
> 
>  > I had attempt at stencils. The main difference between PCB and stencil
>  > your trying to etch 100um~150um instead of 35um. Any professional who
>  > etches stencils, will double side etch. I was trying to etch for QFN
>  > packages with 0.5mm pitch, and could not get the required accuracy. All
>  > the other component pads were usable. It was only this particular IC
>  > that caused me problems. Major factors affecting the accuracy of the
>  > stencil were limitation on my inkjet printer resolution and etch
>  > undercut. I tried compensating for etch undercut and even tried double
>  > sided etch, but failed to get consistent apertures for the 0.5mm pitch
>  > pads. In the end I paid $180 for a brass stencil , which I mounted to my
>  > own frame.
>  > For parts like 0603, 0402 , 0.65mm pitch TQFP, then I think home brew
>  > stencil etching is quite feasible.
>  >
>  > I was new to stencils and solder past printing so maybe someone can
>  > prove me wrong.
>  >
>  >
> 
>

>In the end I paid $180 for a brass stencil , which I mounted to my 
>own frame.

There is or used to be a place that offered plastic stencils at a 
fraction of brass prices.

>For parts like 0603, 0402 , 0.65mm pitch TQFP, then I think home brew
>stencil etching is quite feasible.

CNC drilling can be another option for components in that range 
depending on your requirements.

http://www.pbase.com/eldata/stencils

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@...> 
wrote:
>

"derekhawkins" <eldata@...> writes:
> There is or used to be a place that offered plastic stencils at a 
> fraction of brass prices.

http://http://www.smtstencil.com/

Just to report:

Someone mentioned the material advertised at:

http://renaelectronics.com/product_stencil.htm

for use making stencils.  I bought some and can report that it works
well, much better than I had expected.  The price seems a little high,
but not compared to $180 for a steel stencil.  At $10 (3 sheets in a
$30/pack) it makes good sense for small-scale users. 

I blew the first attempt (my mother claims that I have a congenital
defect inherited from my father that prevents me from following
directions, my wife just says that I am an idiot).  I probably mixed
the developer too strong.

But the second try was almost perfect.  I made a print on transparency
film of the PDF file they provide of shaft encoders, and four of the
six came out perfect, two were slightly over-bitten (sp?) & lost some
interrupter partitions at the periphery.  All cut free of the primary
sheet cleanly.

I have never used FeCl2 on Steel before, & had no idea it could be
chemically machined with such fine detail under simple conditions.

There are a few details that were unclear to me on Rena's website. 
This is what I did:

I just sandwiched the printout against the sensitized material with a
(sort of) clean piece of Plexiglas 1/4 inch (6.35 mm) thick and
exposed it at 7 inches (180 cm) from a two bulb 24 inch florescent
'shop-light' fixture with two 20 W bulbs (one a grow light 'broad
spectrum', one a standard kitchen & bath - just what I had) for 10 to
15 minutes.  

I am suspicious that 15 min was too long, and 10 was too short. 
Systematic (that will be the day) testing would probably perfect the
process.

Then it is just develop & etch.  I don't know if the development needs
to be done in the dark or not.  I did for the first couple of minutes.

Just don't forget to take the protective plastic layer off - it just
doesn't work that way.


-- Dave




--- In Homebrew_PCBs@yahoogroups.com, Markus Zingg <homebrew-pcb@...>
wrote:
>
> Hi group
> 
...

> 
> I hope this helps others. Enjoy!
> 
> Markus
>

This (for me) forms an alternative for stencils supposed to last long, 
cause those I do are a bit difficult (not impossible though) to clean 
and as such I most often use them only once. For most of my cases 
though, the aluminium foil / dryfilm resist method is the way to go 
(again for me) due to the almost non existing costs and availablilty of 
the material (could no longer do without dryfilm resist anyways) and the 
fact that with the prototypes I do there are almost all times changes 
needed anyways.

Thanks for sharing this, I was not aware of the renaelectronics product 
bevore.

Markus

pork_u_pine2000 schrieb:

>
> Just to report:
>
> Someone mentioned the material advertised at:
>
> http://renaelectronics.com/product_stencil.htm 
> <http://renaelectronics.com/product_stencil.htm>
>
> for use making stencils. I bought some and can report that it works
> well, much better than I had expected. The price seems a little high,
> but not compared to $180 for a steel stencil. At $10 (3 sheets in a
> $30/pack) it makes good sense for small-scale users.
>
> I blew the first attempt (my mother claims that I have a congenital
> defect inherited from my father that prevents me from following
> directions, my wife just says that I am an idiot). I probably mixed
> the developer too strong.
>
> But the second try was almost perfect. I made a print on transparency
> film of the PDF file they provide of shaft encoders, and four of the
> six came out perfect, two were slightly over-bitten (sp?) & lost some
> interrupter partitions at the periphery. All cut free of the primary
> sheet cleanly.
>
> I have never used FeCl2 on Steel before, & had no idea it could be
> chemically machined with such fine detail under simple conditions.
>
> There are a few details that were unclear to me on Rena's website.
> This is what I did:
>
> I just sandwiched the printout against the sensitized material with a
> (sort of) clean piece of Plexiglas 1/4 inch (6.35 mm) thick and
> exposed it at 7 inches (180 cm) from a two bulb 24 inch florescent
> 'shop-light' fixture with two 20 W bulbs (one a grow light 'broad
> spectrum', one a standard kitchen & bath - just what I had) for 10 to
> 15 minutes.
>
> I am suspicious that 15 min was too long, and 10 was too short.
> Systematic (that will be the day) testing would probably perfect the
> process.
>
> Then it is just develop & etch. I don't know if the development needs
> to be done in the dark or not. I did for the first couple of minutes.
>
> Just don't forget to take the protective plastic layer off - it just
> doesn't work that way.
>
> -- Dave
>
> --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, Markus Zingg <homebrew-pcb@...>
> wrote:
> >
> > Hi group
> >
> ...
> >
> > I hope this helps others. Enjoy!
> >
> > Markus
> >
>
>