Homebrew_PCBs

Did another board today; the lines were big enough to use toner
transfer so I did it that way, to try out the hotter laminator too.

Things that didn't go so well:

First time, I put the TT paper on the board and ran it through. Came
out curly, I suspect the paper and board have different heat-expansion
amounts. Second time I ran just the board through once, seemed to
help. Since the first time through some of the toner came off,
perhaps the pulling stress was a factor.

First time, I put the hot board into the cold water. Not sure if
stress was a factor here too. Second time I cooled the board first
(see details below).

First time through, the laminator had been at temperature for 7
minutes. By the second time, it was plenty "warmed up". I also
boosted the temperature from 350 F to 360 F.

The green TRF seems to want to put down foil over the spaces beween
close-together lines. This resulted in some micro-shorts. Not sure
if the hotter temperature is causing this, but I sent my whole process
to Frank (Pulsar) to see if he had any ideas.

What worked:

Board was prepped with soap and green scrubbie, as usual. Sanded with
2000 grit paper under running water until the water no longer beaded
off. Dried the board.

Artwork on TT paper as usual, nothing special here. Smallest details
are 11 mil lines with 8.66 mil spaces. The printer doesn't seem to
have a problem printing this.

Laminator at 360 F. At least 10 minutes warmup, probably more like
15. Run board through once to preheat (cover copper with blank paper
in case there's junk on the rollers), then three times with TT paper
on it - short edge first, then long edge first, then diagonally. Once
might have been enough, but I wanted to compensate for cheap rollers ;-)

Place board on table saw (cold cast iron), board side down. Press on
top (paper side) with push block, which has rubber sole. This held
the TT paper and hot toner against the copper while cooling it, which
took only a few seconds as the cast iron sucked away the heat.

Put in cold water. DON'T POKE AT THE PAPER! It will come off on its
own. I poked it the first time, again, that may have been a factor in
the toner detachment.

Dry. It was fairly well stuck; I could gently wipe it with a paper
towel and nothing came off.

Green TRF - one pass, short edge. Cool as above, peel. 100%
coverage, aside from the issue with the micro-shorts it was nearly
perfect.

Etch, 4-5 minutes heated CuCl. Strip toner, tin plate.

Cleaned up micro-shorts with an x-acto knife.

To those who use TT without TRF: comments on how well toner alone
blocks etchant? Do you get pinholes in the copper?

DJ,
From my own testing, when using the "green stuff", you actually "flattening"
and evening out the toner a bit. After removing the paper, the toner is
actually filled with micro hills and valleys.The green film is based on a
high temperature mylar and this combined with heat evens out the toner.
There is nothing special about the green color, any color heat transfer film
works. I've tried gold and other patterns.

You can get a similar effect by using the silicone coated release sheet from
labels.

Myc

On Mon, Jun 1, 2009 at 12:57 AM, DJ Delorie <dj@...> wrote:

>
>
>
> Did another board today; the lines were big enough to use toner
> transfer so I did it that way, to try out the hotter laminator too.
>
> Things that didn't go so well:
>
> First time, I put the TT paper on the board and ran it through. Came
> out curly, I suspect the paper and board have different heat-expansion
> amounts. Second time I ran just the board through once, seemed to
> help. Since the first time through some of the toner came off,
> perhaps the pulling stress was a factor.
>
> First time, I put the hot board into the cold water. Not sure if
> stress was a factor here too. Second time I cooled the board first
> (see details below).
>
> First time through, the laminator had been at temperature for 7
> minutes. By the second time, it was plenty "warmed up". I also
> boosted the temperature from 350 F to 360 F.
>
> The green TRF seems to want to put down foil over the spaces beween
> close-together lines. This resulted in some micro-shorts. Not sure
> if the hotter temperature is causing this, but I sent my whole process
> to Frank (Pulsar) to see if he had any ideas.
>
> What worked:
>
> Board was prepped with soap and green scrubbie, as usual. Sanded with
> 2000 grit paper under running water until the water no longer beaded
> off. Dried the board.
>
> Artwork on TT paper as usual, nothing special here. Smallest details
> are 11 mil lines with 8.66 mil spaces. The printer doesn't seem to
> have a problem printing this.
>
> Laminator at 360 F. At least 10 minutes warmup, probably more like
> 15. Run board through once to preheat (cover copper with blank paper
> in case there's junk on the rollers), then three times with TT paper
> on it - short edge first, then long edge first, then diagonally. Once
> might have been enough, but I wanted to compensate for cheap rollers ;-)
>
> Place board on table saw (cold cast iron), board side down. Press on
> top (paper side) with push block, which has rubber sole. This held
> the TT paper and hot toner against the copper while cooling it, which
> took only a few seconds as the cast iron sucked away the heat.
>
> Put in cold water. DON'T POKE AT THE PAPER! It will come off on its
> own. I poked it the first time, again, that may have been a factor in
> the toner detachment.
>
> Dry. It was fairly well stuck; I could gently wipe it with a paper
> towel and nothing came off.
>
> Green TRF - one pass, short edge. Cool as above, peel. 100%
> coverage, aside from the issue with the micro-shorts it was nearly
> perfect.
>
> Etch, 4-5 minutes heated CuCl. Strip toner, tin plate.
>
> Cleaned up micro-shorts with an x-acto knife.
>
> To those who use TT without TRF: comments on how well toner alone
> blocks etchant? Do you get pinholes in the copper?
>
>


[Non-text portions of this message have been removed]

Myc Holmes <mycroft2152y@...> writes:

> From my own testing, when using the "green stuff", you actually
> "flattening" and evening out the toner a bit.

It leaves a pretty thick layer of green stuff, too. The peeled-off
film is clear where the artwork was. It claims to "seal" the toner,
filling in the pinholes and making the overall mask less porus, which
I can certainly believe.

Frank got back to me and suggested a cooler temp setting and some
other tricks, I'll try them out and see what works.

I don't do anything that complex. I set the temperature on my external control to 260 *F, The $25 GBC laminator. Takes about as long to heat up as it takes to print out the transfer. I use Hammermill Color Laser Glosss, 32# (16311-0). I lightly sand the board with 220 grit paper. I do a double wipe with alcohol. I do not preheat the board. I align the pattern on the board and hold it place with fingers. One pass will tack the toner, reverse direction of board on a second pass. This is all I need to do for small boards ~2 sq. in. or so. Larger boards I run 4 times changing the leading edge on each pass. I get nearly no spreading. The paper does not wrinkle. As usual the pattern does shrink just a bit.

Immediately out of the laminator I run water and liquid hand soap on the paper. Lightly scratch the paper with fingernails. The paper becomes translucent almost immediately. I can then rub/roll off a top layer of paper, then roll off the layer against the copper. Takes less than a minute to get the paper off. I can then very lightly scrub the board with a fine nylon abrasive pad.

I almost never loose any traces.

RD

[Non-text portions of this message have been removed]

"RICHARD HEILIGER" <rdheiliger@...> writes:

> I almost never loose any traces.

My boards tend to have enough traces on them that "almost never" is
often enough to ruin most boards.

What toner are you using that sticks at 260F? Mine barely sticks at
320F.

I've been playing with the GBC laminator today. I jumpered one of the thermal switches so I could get a higher temperature on the 3 mill setting. I have a digital meat probe that will insert in thru the inlet plastic to touch metal. There with the set switch to 5mil setting the temp runs about 320F max. is that about what others are getting?

With the switch set in the 3mil position where the thermal switch is jumpered (testing purposes only) out the temp will get well over 425F.

Any idea where the over temperature switch cuts out? I removed that to be sure it wasn't shuting off early.

I have to get the temp up over 300F myself for the traces that were printed on normal laser printers.

With my brother 2140 laser printer I get the temperature up over 350F, then start running a double sided .062 board (2-1/2"X 3-12") thru with different leading edges each pass. By the time 6 or 8 passes are completed, the temperature is up around 400F to 425F. I got good toner transfer both times.

I did find the toner does not stick as well as when I was using two metal plates clamped together. Does running the PCB back thru the laminator after removing the paper help make the toner stick better?

I may have to order another one of these $25 laminators just to have a spare if (when??) this one burns out.

Ken H>

--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:
>
>
> "RICHARD HEILIGER" <rdheiliger@...> writes:
> > I almost never loose any traces.
>
> My boards tend to have enough traces on them that "almost never" is
> often enough to ruin most boards.
>
> What toner are you using that sticks at 260F? Mine barely sticks at
> 320F.
>

On 01/06/2009, at 2:57 PM, DJ Delorie wrote:

> To those who use TT without TRF: comments on how well toner alone
> blocks etchant? Do you get pinholes in the copper?
>

Just getting back to this - I get a few holes in the toner in larger
areas, but never actual holes through the copper. I am just fooling
with this and running ridiculously low on toner anyway, but I've
certainly never had a trace actually interrupted by a toner hole - I
do keep them as wide as practicable, plenty of 16mil ones, don't think
I've gone thinner.

(I did some unofficial Delorie spirals at 6mil, but I've yet to hand-
iron them evenly enough to bother etching)

PG

I use an 8 year old Minolta PagePro 1250 laser printer. I have used the factory toner and remanufactured cartridges from two different sources. All give the same result. I have used a different laminator in the past that did not give the same results even tho I had the temperature the same. That laminator used a faster feed rate. I believe that time/temperature is a determining factor in getting good results. Time/temperature is also likely a major factor in the printer itself. I would think that the higher the page/minute rate of the printer the higher the printer temperature needs to be. Not sure the temperature the printer runs at is necessarily the fusing temperature of the toner. I did verify the temperature of my laminator with a candy thermometer to verify the reading on my control.

The majority of traces on a typical board I make are 12 mil. If I loose a trace it is always near the edge. This was true even if I used the iron method. Seems the heat dissipates near the edge??? This is the main reason I use two passes and reverse the board on the second pass.

I would say that toner transfer is mainly a method of producing prototype boards. Having to repair a trace or two is not a big deal on one up prototypes. If a trace falls off it is obvious before I etch. If I see it and it is in a critical place. I wipe off the toner with acetone and rerun the board. I have run batches of 50 boards using toner transfer with no traces missing.

RD



[Non-text portions of this message have been removed]

One thing I always do is run a 50 mil trace around the outline of the
board, so that none of the "real" traces are the ones on the outside
edge.