Homebrew PCBs

I have a GBC laminator also, it is wonderful, it's so consistent in 
transferring the toner, I could never get a iron to work that well.

By the way, where did you find the silicone sheets? I would like to try them.


At 02:55 PM 5/17/2005, milwiron@... wrote:
><stefan_trethan@g...> wrote:
> > Nice to hear someone was done work on it too. sadly i have to disagree on
> > almost all points.
>
> > On Mon, 16 May 2005 14:02:02 -0500, <milwiron@t...> wrote:
>
> > > 2. Use two layers of masking tape at the outside edges of the paper to
> > > hold the squeegee .008" off the paper.
> > > I'm using a 2" bar of acrylic as a squeegee.....
>
> > I disagree on this one. I use a steel squeegee and wipe it off as thin as
> > i can, no spacers.
> > I found it works better than a thick layer. I hold the squeegee almost
> > vertical and apply a lot of force, basically scrape off as much as you
> > can....
>
>Hi Stefan,
>I'm not sure how you can say a method is "wrong" if it works for me.
>What I posted works very well with the equipment and materials I have on hand.
>I use a bar of acrylic because it's rigid, glass smooth and is easy to 
>clean since any cured silicone just peels off. Using the acrylic bar and 
>the masking tape spacers gives me perfect coatings of uniform thickness 
>every time, it's one less variable to deal with.
>
> > > 3. Let it cure -completely- for 4 to 7 days. Longer doesn't hurt.
>
> > Don't see the need, even a thick layer (mm) is cured in half an hour, i
> > have used a coated paper after 30 minutes with no adverse effects.
>
>I get better results letting the silicone go through its full post cure 
>period.
>For years I worked with dozens upon dozens of different types of single 
>and two part silicones in industrial applications, very few silicones are 
>fully cured in a couple of hours.
>Most of the silicones you'll ever run in to are compounded to be 100% 
>solids after full cure, full cures can take days or even weeks. Less than 
>a full cure and it's not 100% solid.
>
>In my experiments I found that with anything less than a full cure I had 
>the silicone sticking to the copper board and the toner not releasing 
>entirely... the longer I let it sit the better it worked for transfers. 
>And with a full cure there's no risk of gluing the silicone paper to a 
>fuser roller or leaving behind any prepolymers to contaminate the printer.
>Letting the silicone paper sit for a week isn't a big deal for me if I 
>plan ahead. (No, planning ahead doesn't always happen)
>
> > > 4. I'm printing with a HP2100 laser printer, factory cartridges only.
> > > Off brands of toner don't always work.
> > > The first time I use a piece of silicone paper I run the whole sheet,
> > > tape and all through the printer.
> > > 5. Lightly sand and clean PCB stock with lacquer thinner, not acetone.
> > > I've gotten very poor results using acetone, I don't know why. Trim the
> > > printed silicone paper to fit.
>
> > I always use acetone, and have very good results. i do not like the
> > possible adverse effects to health of laquer thinner.
>
>One thing I learned in my Polymeric Chemistry courses is that all 
>hydrocarbon and chlorinated solvents are hard on living tissue. If you 
>think acetone is somehow better for you than lacquer thinner you're not 
>looking at the whole picture.
>Any solvent that can dissolve thermoplastics like polystyrene or acrylic 
>will make a mess out of your liver, lungs and nervous system. The above 
>also goes for "natural" solvents, orange oil based solvents are a tad 
>scary. It's natural, yeah and it removes dried paint. Asbestos and uranium 
>are natural too.
>
>Cancer is bad no doubt, so is permanent damage your nervous system and 
>have you tried to get a new liver lately? ;-)
>The bottom line is, I've known people who died from cancer and others from 
>liver failure and both together also. It's a tossup which one I'd choose.
>
>Two over simplified but good to remember rules are:
>1. If you can see it don't breath it.
>2. If you smell it, it's too late.
>
>Acetone has an affinity to water/moisture/humidity, something I've learned 
>to try and avoid during copper cleaning before transfer.
>To clean a board after etching and drilling I use a small sandblast 
>cabinet with glass beads to clean off 99% of the toner in maybe 2 seconds. 
>Then I use lacquer thinner for any minute traces of toner left behind.
>I found if I used acetone at this point the copper traces and pads, if 
>left uncoated, started to turn green at the edges after a day or two. This 
>doesn't happen with lacquer thinner.
>Again, these are my observations based on what I've run in to. Other 
>people may get varied results.
>
>About less potent stuff:
>In my limited years of making toner transfer prototypes I've never had any 
>success with soaps or detergents for cleaning the copper, even with 
>distilled water rinses. Hopefully somebody has had better luck out there.
>
> > > 6. Run it 5 to 6 times through GBC Laminator.
>
> > Run one time through old copier fuser converted to slow speed with 
> chicken
> > grill motor.
>
>GBC laminator, this is what works best for me.
>I found 5 times quickly through a GBC laminator gives a more even heat and 
>transfer than once through a slow fuser, I have both and it doesn't take 
>any longer time-wise since the GBC is running 5 or 6 times faster.
>
> > > 7. Let cool and peel.
>
> > peel when still hot. (thicker coating can be peeled cold, but thin 
> coating
> > is better peeled hot)
>
> > > The results are 99.99% perfect, there's very little touch up.
>
> > the results are 100% perfect, if you have done nothing wrong (e.g. bad
> > cleaning, pits in silicone, creases..)
>
>I found peeling the paper when the board is hot can damage the transfer 
>since the toner is still soft.
>I prototyped a 3 x 6 inch board, every other board had a couple of 15 to 
>20 thousandths diameter pits of missing toner to fix. From your previous 
>posts I didn't get the impression you were doing any better than that, I 
>may be very wrong.
>
> > > To reuse the silicone paper, clean it with lacquer thinner and stick 
> the
> > > leading edge to a carrier piece of paper with a glue stick.
>
> > I just print the sheet again. why do you stick it to another paper?
>
>I trim the silicone covered paper away from the uncoated paper for better 
>registration on the board.
>To get it to go through the printer after the first printing and trimming 
>it needs a carrier sheet with my HP2100.
>
>Once again, what I posted is what I found worked for me, I hope I made 
>that clear in my first post. I was simply trying to share that 
>information.  If I somehow twisted your panties in a knot by posting, I 
>humbly apologize.
>
>Just a quick addition: I've found using commercially available .010 inch 
>thick silicone sheeting attached to a carrier sheet of paper works 
>extremely well and the preparation time is next to nothing. Best of all 
>you don't have a dozen sheets of paper hanging around and laying on every 
>horizontal surface in your shop.
>
>I do greatly appreciate you sharing your original concept and experiments 
>with silicone paper.
>Denny
>
>
>
>
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>
>
>
>

Cecil Bayona
KD5NWA
www.qrpradio.com

'Never argue with an idiot. They drag you down to their level then beat you 
with experience.'