Short version: I have had success making phototools for negative
photoresist film (Riston) using both the MegaUK
LaserStar and an un-named A4 transparency film from
Canada. The Canadian film is superior in that one side
is gloss, the printing side is near gloss and the
material itself, in total with its surfaces,
creates no appreciable diffusion of light. I don't have
any problems with "holes" in the toner, with either
of these films, using a Brother HL-5250DN laser
printer.
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Hi Jefferson,
You wrote:
> Am choosing between LaserStar and JetStar premium for making Masks.
> Anyone who has tried them both?
> I usually use 85 GSM tracing paper, but the black areas are full of holes.
> Will the Jetstar/LaserStar have fully black areas?
I assume you are referring to:
http://www.megauk.com/artwork_films.phpI have used Laserstar with a Brother HL-5250DN for making negative
phototools (generally black but transparent where the copper tracks will
remain) and have had no trouble with "holes" in the toner.
There could be various reasons for such holes or unwanted distribution
of toner. One is the toner sliding around on the surface after being
deposited (or while being deposited) by the drum and before (or while)
being melted by the fuser rollers. I think the toner might be shaken
around if the film vibrated inside the printer, between the drum and the
fuser rollers. This may happen more if it is stiff and is used in a
relatively small piece, so one end or the other is flapping around,
hitting things, inside the laser printer while the toner is supposed to
be sitting still on it.
Another cause of "holes" in the toner may be that the fuser roller
temperature and pressure is inadequate to completely bond the toner to
the film. (I have read that Brother laser printers have a higher fuser
roller temperature than printers of other companies. However I don't
have any solid references for this.) Again, a shiny film is probably
harder to bond toner to than one with a special coating or one which
simply has a matte surface, and therefore a more complex, non-flat,
surface to bond to.
It is my impression that these problems are worsened by the film having
a completely smooth - that is shiny/glossy - surface.
As far as I know, the LaserStar is simply drafting film - matte on both
sides and perhaps with the plastic itself having a somewhat milky
(optical diffusing) nature, though most likely the plastic itself is
water-clear transparent. As far as I know, this material is what is
commonly referred to by the DuPont tradename "Mylar". I have a roll of
drafting film from the early 1980s for a big old (piano-sized) Benson
plotter. It is slightly thicker (90 microns) but otherwise looks the
same as LaserStar - and it behaves just the same. I suspect that any
"Mylar" drafting film will work the same way. I know of no evidence
that the LaserStar is coated with anything, or that it is is "specially
formulated". It is about 88 microns thick.
As best I understand it the following terms refer to the same material:
1 - Mylar.
2 - boPET = Biaxially Oriented Polyethylene Terephthalate:
http://en.wikipedia.org/wiki/BoPET Polyethylene Terephthalate has a far more complex structure than
ordinary Polyethylene ("Polythene").
The Biaxially Oriented film is made by stretching the amorphous
film so the polymer molecules are stretched, aligned parallel to
the surface and then heat treated to set them in this position and
make them transparent. (Many soft-drink and other plastic bottles
are made of Polyethylene Terephthalate using a blowing processs,
which I guess does a similar job of aligning the molecules.)
3 - Polyester. "Polyethylene Terephthalate" is too much of a
mouthful, so the term "Polyester" is used instead. This
does not imply that the material has been biaxially oriented,
but as far as I know, any "polyester" film used like a piece
of paper for printing or drawing would be BOPET.
http://en.wikipedia.org/wiki/PolyesterThe double-matte nature of the LaserStar film seems to be quite friendly
to the toner. Even though the drum of my printer is quite old, I get
images which are solid enough and consistent enough to expose Riston
well. (I am using a 500 watt quartz halogen incandescent floodlight -
see my previous messages.) With a photodiode, using white incandescent
light, I can tell the black areas pass only about 1/7 of the light which
are passed by the clear areas. There is some variation in darkness, and
the lighter parts of the toner are the limiting factor, but these are
smaller than the size of the photodiode so I don't know how they
attenuate light. I guess the worst case would be a 4:1 or 5:1 reduction
in light. In my experience this level of contrast is quite sufficient
to get clear exposures with Riston.
I recently bought some (presumably) BOPET film which I think is even
better. The double-matte nature of LaserStar means that some light is
reflected by both surfaces and all the light which passes through both
surfaces is diffused. Therefore LaserStar does not produce a clear
shadow. This may not matter if the toner side is pressed to within a
few microns or tens of microns of the thin BOPET protective film on top
of the Riston. This can be hard to achieve. In general, it would be
better to have a phototool which did not diffuse the light at all,
especially with a narrrow light-source such as the incandesent 400W lamp
at 45cm or so, with most of the light coming from an angle of 0.15
radians. I bent the reflector a little to make the light source more
compact, but I think this is generally not necessary with the film I am
describing.
This inkjet / laser transparency film from Canada is 11 microns thick
and is available in A4 and A3 sizes. It is gloss on one side and very
close to gloss on the treated side, which works well with my HL-5250DN
(true 1200DPI mono), and my 600DPI color Brother HL-4040CN. There is no
appreciable diffusion of the light which passes through this material,
so for the purposes of a phototool creating a shadow, I regard it as
being as transparent and non-diffusing as a photographic film phototool.
http://asc365.com/?ID=WW00013This is from ASC365.COM in Toronto (with an office in Miami).
In Melbourne (Australia) there is an eBay seller who is evidently
associated with the above company:
http://myworld.ebay.com.au/printingsupplies2009/ http://stores.ebay.com.au/ascscreenprintingThey only ship to Australian destinations, so if viewed from other eBay
sites, this seller may show nothing is available.
asc360.com apparently ship to all countries, but they need to
communicate via email regarding shipping costs. The A4 sheets are
USD$0.45 each and the A3 sheets are USD$0.90.
They also sell a "blackening agent" on the same page.
There are plenty of Brother laser printers available second hand, often
for $50 or so. Most of them are 600DPI, but that will be fine for all
practical purposes. A 600DPI laser printer will give a much sharper
image than is possible with any inkjet, as far as I know, since there is
no diffusion of liquid ink.
The 1200DPI Brother printers such as the now-obsolete HL-5250DN or its
current model equivalent HL-5350DN (and related models) are true 1200
DPI. My old HL-5250DN produces an extraordinarily sharp image. I have
used it to make Riston lines as small as 0.005 inch with 0.005 inch
spacings (127 micron) That was pushing the limits, but the results were
really solid at 0.010 inch (254 micron) which is as small a track as I
would probably want on a PCB. (Etching is another matter, which I don't
yet have much experience with.)
The HL-5250DN will handle legal paper - 8.5 x 14 inches (216 x 355mm) -
while the current model series has a maximum paper size of A4 (210 x 297
mm).
- Robin
http://www.firstpr.com.au/pcb-diy/