On Tue, 17 May 2005 14:55:41 -0500, <
milwiron@...> wrote:
> 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.
I do not say it is wrong, never did. It is merely that my experiments have
let to different findings, in most points, which is surprising, at least.
This is still in the very early stages, nobody can possibly know anything
for sure.
> 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)
It works for me when it no longer smears. I will try if if longer curing
makes for better cold-peel, might well be.
> 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.
Laquer thinner solves acrylic and polystyrene 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.
Whatever, all i know is Acetone is classified Xi, irritant, while laquer
thinner is Xn, possible bad permanent effects on health. Of course acetone
is bad on the liver, so is alcohol, and some people drink that.
> 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.
Never seen this going green, i use another board edge or a steel squeegee
to scrape the toner off insead of blasting. Then i use acetone for the
rest. I would suspect the green stuff beeing caused by residual etchant, i
have had that when i didn't rinse properly. I can't figure out how acetone
would cause the discoloration, i would rather suspect the thinner putting
something on there which protects the copper?
> 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.
I used abrasive kitchen cleaner, and it did work, but i prefer the dry
method now.
> 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.
I don't notice any uneven heat with the fuser, but i have no laminator. My
reasoning is the board cools between passes so one pass is ideal.
> 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.
I do get the holes when i peel cold, but not when i peel hot. Peeling cold
sometimes works 100%, but only sometimes, while peeling hot works all the
time.
> 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.
I see. the A3 size of the fuser is helping here i guess. In the end i most
likely end up cutting it and discarding the paper, 'cause i will want to
print multiple views on one sheet (like both copper and component legend
sides). I do not like the stick-to-carrier method, i noticed the toner
darkness is less when the paper is thicker.
> 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.
You did not twist anything, just causing confusion by basically
contradicting many hours of painstaking experiments.
> 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.
Interesting, is it high-temp? i wouldn't have a source for such sheets
anyway i fear but it might be interesting for those who just can't find HT
silicone.
Also, would latex work? i remember someone mentioning using HT silicone as
replacement for latex masks... I can get liquid latex at my chemicals
supplier, but i wouldn't know if it can stand the heat...
ST