Yes, the wrinkling is a problem. I even got a crease when i tried, so
i didn't try again.
Possibly the sheets can be dried between two plates in an oven or some
such complicated method.
You don't need an inch, i usually draw a 5mm line around my boards and
that's enough.
Sometimes i also forget, and apart from the board outline rarely lose
any traces that way.
Clearly your surface preparation is not sufficient. I didn't know you
didn't sand it, try that first and then we can look further.
You probably won't avoid shrinkage with any heat setting, you need
well over 100°C to melt toner and i think the shrinkage is mostly from
expelled water.
If it is a huge problem you need another paper.
The toner is strong enough to resist the etchant almost permanently,
if done right. So it's no problem to wait as long as it took to etch
one side again to finish the other, as long as your traces are wide
enough so that undercutting is no problem. The other side always takes
much longer to etch for mee too (more copper i suppose).
ST
On Sun, Dec 21, 2008 at 2:39 AM, jerrytr2.com <jerry@...> wrote:
> --- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
> <stefan_trethan@...> wrote:
>>Apparently
>> pre-shrinking the paper by running it through the laminator before
>> printing has also brought relief to some.
>
> ∗∗∗ I tried this. Sure can get some serious shrinkage with a full
> sheet. In fact, the paper ( HP Q2419A ) just wrinkled up. Obviously
> wouldn't have worked at all.
>
> I tried again this morning. Used a board about two inches
> too big in each dimension - so there was an inch of dead space on
> each side. I printed onto the HP glossy paper with the following
> settings on my Brother MFC8600DN:
> ∗ resolution 1200HQ
> ∗ "transparency" ( figured those are smooth, and the printer might
> put down more toner )
>
> I cleaned the board with laquer thinner, and then with denatured
> alcohol. Trimmed the printout a bit smaller than the board, and
> taped it on with Scotch Magic tape.
>
> Gave it 5 passes through the laminator (GBC 95P ) doused it in
> cold water, and then let it in hot soapy water for about 15 minutes.
> It mostly worked, although the corners were still crumbly, and I had
> to spend about a half hour rolling the soft paper off.
>
> Bits of toner were coming off in the ferric chloride bath. I
> fished the board out and touched up with a fine-tip marker pen.
>
> The circuit side etched faster than the back side, so when it was
> done ( and the back side still had a ways to go ), I taped off the
> whole circuit side with masking tape and finished etching off the
> other side. It's not pretty, but it'll work.
>
> Things I want to try next time:
>
> ∗ Sand the board. I think that a bit of a tooth will help the
> toner stick. Say 400 or 600 grit.
> ∗ Try different temps. I think maybe the "foil" setting is a bit
> hotter than needed. I noticed some pots on the circuit board in the
> laminator. A lower temp should help with the shrinkage. Would like
> it hot enough to melt the toner, but no hotter.
>
> - Jerry
>
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