Homebrew_PCBs

----- Original Message -----
From: "patroclus04" <patroclus04@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, February 19, 2006 9:15 AM
Subject: [Homebrew_PCBs] Photolithography


> Hello,
> I've been doing some PCBs by "hand" for a year or so.
> Now I would like to use SMD and superficial IC, and I need more
> accuracy and posibility of making several boards.
>
> I tried 4 or 5 times with tonner transfer. Results are not good.
>
> I use magazine paper, I tried 2 o 3 of them. Glossy.
> I print using a LaserJet 6. I iron at high temp, for 10 minutes or
> even more. I wash in warm water, and leave there a few minutes more.
> Then I peel the paper (it takes time and effort, sometimes I just
> damged a track). The pattern is firmly transfered, and it actually
> takes a lot of effort to remove from the copper using disolvent. BUt
> the pattern is heavily damaged. Many track cutted, pads missing,... I
> manage to get some better, but I need very good acuracy for SMD, can't
> just finish by hand...
>
> I don't know what more I can do...
> I'm thinking on going into photographic methods. I was thinking on
> getting photosensitive boards, print a mask, and expose it to UV
> light. Then, as far as I'm concerned, I will have to put in developer,
> and then etch.
>
> Can you guys help me out? any advice??
> Any ideas??

That's the technique I use, it's very easy. You need to buy or make a UV
exposure unit, easiest way is to buy a couple of 12" UV tubes and 12"
fluorescent fixtures, swap the tubes and put them in some sort of box with a
sheet of glass for the PCB and artwork. Shouldn't cost more than 20 GBP.

Leon
--
Leon Heller, G1HSM
leon.heller@...
http://www.geocities.com/leon_heller

----- Original Message -----
From: "patroclus04" <patroclus04@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, February 19, 2006 10:35 AM
Subject: [Homebrew_PCBs] Re: Photolithography


>
> Hi, thanks for your reply.
> I'm not sure if I understud. Should I use both a UV light tube and a
> fluorescent tube?

No, two UV tubes.

>
> Also, I would need developer, and I think that is.

Sodium hydroxide, about 12g/L. Two teaspoons is about right.


> After printing in trasparent paper, I need to fix it to the board in a
> dark room (using tape maybe?) and then put it into the light box for 5
> or 10 minutes.

You don't need a darkroom. I just put the transparency in contact with the
board (print side down), make sure it is positioned correctly, and put the
board and transparency on the glass. I then put a heavy book on top of the
board to ensure it is pressed down. You have to experiment to get the
correct exposure, it mainly depends on the distance from the lamps. I use 13
minutes.

>
> Then go out, put it in developer a few minutes more, and then ferric
> clorhidre.

That's right. The unexposed resist goes purple in the developer so you can
take it out and rinse it when all the purple has gone.

>
> More or less, is that it?

Yes


> Developer liquid can be stored and reused many times?

It can last a long time. As it's very cheap, I use fresh each time.

Once you get the process right, it's completely repeatable and gives
excellent results. I don't have much trouble with 8 mil tracks and 0.5 mm
lead spacing ICs.

Leon
--
Leon Heller, G1HSM
leon.heller@...
http://www.geocities.com/leon_heller

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> >
> > Also, I would need developer, and I think that is.

> Sodium hydroxide, about 12g/L. Two teaspoons is about right.

> > After printing in trasparent paper, I need to fix it to the board in a
> > dark room (using tape maybe?) and then put it into the light box for 5
> > or 10 minutes.

> You don't need a darkroom.

> I just put the transparency in contact with the board (print side
> down), make sure it is positioned correctly, and put the board and
> transparency on the glass. I then put a heavy book on top of the board
> to ensure it is pressed down. You have to experiment to get the correct
> exposure, it mainly depends on the distance from the lamps. I use 13
> minutes.

> >
> > Then go out, put it in developer a few minutes more, and then ferric
> > clorhidre.

> That's right. The unexposed resist goes purple in the developer so you
> can take it out and rinse it when all the purple has gone.

> >
> > More or less, is that it?

> Yes

> > Developer liquid can be stored and reused many times?

> "and put the board and transparency on the glass. I then put a heavy
> book on top of the board to ensure it is pressed down. "

> I can't see what you say... Sorry. as this may sound stupid.. but..I put
> the PCB on top of glass?? the glass on top?? If you put a heavy book on
> top, how can UV light expose the board??

----- Original Message -----
From: "patroclus04" <patroclus04@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, February 19, 2006 8:51 PM
Subject: [Homebrew_PCBs] Re: Photolithography


>
> Thank you, I think I get the point. Just have two questions about.
>
> "and put the
> board and transparency on the glass. I then put a heavy book on top of the
> board to ensure it is pressed down. "
>
> I can't see what you say... Sorry. as this may sound stupid.. but..I
> put the PCB on top of glass?? the glass on top?? If you put a heavy
> book on top, how can UV light expose the board??

The glass is above the tubes. The transparency is touching the glass, the
PCB is on top of the transparency, and the book is on top of the board.
Plastic foam would be better, as a pressure pad, but makes the construction
more difficult. Vacuum is even better, and is used by PCB manufacturers.

>
> the other question is regarding to UV light. I don't know where to get
> these kind of lamps... I heard of some people usinf fluorescent lights
> with fair results.. but I suppose it is not enough. I would like to
> build one of those boxes you guys talk about. I suppose it will also
> be usefull to erase EVPROMs..

Suitable UV lamps are available from suppliers like Farnell and RS. The
frequency used for EPROM erasure is different (shorter wavelength). EPROMs
aren't used any more.

Leon

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>----- Original Message -----
>From: "patroclus04" <patroclus04@...>
> > I'm thinking on going into photographic methods. I was thinking on
> > getting photosensitive boards, print a mask, and expose it to UV
> > light. Then, as far as I'm concerned, I will have to put in developer,
> > and then etch.<snip>
>
>That's the technique I use, it's very easy. You need to buy or make a UV
>exposure unit, easiest way is to buy a couple of 12" UV tubes and <snip>

----- Original Message -----
From: "Len Warner" <yahoo@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, February 19, 2006 9:26 PM
Subject: [Homebrew_PCBs] Re: Photolithography


> At 10:15 06/02/19, Leon Heller wrote:
>>----- Original Message -----
>>From: "patroclus04" <patroclus04@...>
>> > I'm thinking on going into photographic methods. I was thinking on
>> > getting photosensitive boards, print a mask, and expose it to UV
>> > light. Then, as far as I'm concerned, I will have to put in developer,
>> > and then etch.<snip>
>>
>>That's the technique I use, it's very easy. You need to buy or make a UV
>>exposure unit, easiest way is to buy a couple of 12" UV tubes and <snip>
>
> Leon, notice the OP appears to be in Spain, not our gloomy northern
> latitudes: he may be able to get by with a daylight exposure as long
> as the sky is clear so UV is not unduly attenuated.
>
> Simplest way to make an exposure frame is to tape artwork to board
> and place in ziplock polythene bag with a thick slab of spongy foam
> plastic behind. Squeeze the air out, seal the bag tight (fold end & use
> sticky tape seal if you can't get a ziplock bag) then you will have
> many minutes while the air pressure clamps your artwork down evenly.
>
> Remember that UV levels will fall off either side of mid-day and vary
> with the season, but the exposure latitude of the photoresist is
> fairly large so it should not be difficult to learn suitable adjustments
> and get repeatable results.
>
> With experience, you can judge the adequacy of the exposure by the
> ease and cleanliness of development. You can create a test strip by
> sliding a cover slip in stages from an unused area of the board, to
> leave a series of steps to judge the minimum usable exposure time
> (and the maximum too, if you use scrap board).

I've heard of people in California doing it that way, as well.

Leon
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><snip>I'm thinking on going into photographic methods<snip>
>
>Can you guys help me out? any advice?? Any ideas??

----- Original Message -----
From: "patroclus04" <patroclus04@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, February 20, 2006 9:00 AM
Subject: [Homebrew_PCBs] Re: Photolithography


>
> Thanks. So, as I se,, the light goes inside the box, and the board
> outside, facing down on the light.
> I suppose UV light is not good to take.

It's not a good idea to stare at it for long periods, or expose the skin
directly to it. I haven't bothered to enclose mine completely.

>
> I just meet a person that uses a fluorescent light tube, and it works
> for him. Just 10 minutes exposure at 10cm. He puts the crystal on top
> of the board, with some weights outside.
>
> I would like to do some test without gettin much into mess. So I might
> try this solution, and if it goes well, then build a proper box. Does
> the box have any special purpose appart from what I said??

No. Don't have the tubes too close to the board, it's quicker but you lose
some definition because the light is less collimated.

>
> Also, if you want to use only a piece of the board. Can you just cut it
> before exposing?? what is best?

That's what I do. Leave the protective film on it, of course, before
cutting.

Leon
--
Leon Heller, G1HSM
leon.heller@...
http://www.geocities.com/leon_heller

>Thanks. So, as I se,, the light goes inside the box, and the board
>outside, facing down on the light.
>I suppose UV light is not good to take.
>
>I just meet a person that uses a fluorescent light tube, and it works
>for him. Just 10 minutes exposure at 10cm. He puts the crystal on top
>of the board, with some weights outside.
>
>I would like to do some test without gettin much into mess. So I might
>try this solution, and if it goes well, then build a proper box. Does
>the box have any special purpose appart from what I said??
>
>Also, if you want to use only a piece of the board. Can you just cut it
>before exposing?? what is best?
>
>Thank you
>
>
>
>
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>If Files or Photos are running short of space, post them here:
>http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
>Yahoo! Groups Links
>
>
>
>

----- Original Message -----
From: "Vlad Krupin" <vlad.cnc@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, February 21, 2006 2:18 AM
Subject: Re: [Homebrew_PCBs] Re: Photolithography


> David, thanks for the great description of your process. I have one
> question
> however:
>
> On 2/20/06, David Hopkins <davhop@...> wrote:
> [snip]
>
>>
>>
>> To hold the board and artwork together I use two sheets of 10mm glass 300
>> x
>> 300mm. The sensitized board and the artwork are held between the two
>> sheets
>> of glass and they are held together with large spring paper clips. The
>> reason for two sheets of glass is to do double sided boards.
>>
>> Before the glass I used to use 10mm Perspex (Acrylic) however this
>> scratches easily and one of the trainees spilt developer on them and
>> ruined
>> the Perspex.
>
>
> Doesn't glass (or at least most kinds of glass) tend to absorb UV rays? I
> was under the impression that this was the case. As a result I first tried
> using acrylic, and after finding that it scratches too easily, ended up
> using the thinnest glass I could find -
> http://www.krupin.net/serendipity/uploads/pcb_making_exposure_frame.jpg
>
> It sounds to me that using thick glass would seriously slow down the
> exposure time, especially for people who are using a less powerful light
> than the one you have.

Glass doesn't absorb the long-wave UV used for PCBs., unlike, say the
shorter wavelength used for EPROM erasure.

Leon

>David, thanks for the great description of your process. I have one question
>however:
>
>On 2/20/06, David Hopkins <davhop@...> wrote:
>[snip]
>
> >
> >
> > To hold the board and artwork together I use two sheets of 10mm glass 300
> > x
> > 300mm. The sensitized board and the artwork are held between the two
> > sheets
> > of glass and they are held together with large spring paper clips. The
> > reason for two sheets of glass is to do double sided boards.
> >
> > Before the glass I used to use 10mm Perspex (Acrylic) however this
> > scratches easily and one of the trainees spilt developer on them and
> > ruined
> > the Perspex.
>
>
>Doesn't glass (or at least most kinds of glass) tend to absorb UV rays? I
>was under the impression that this was the case. As a result I first tried
>using acrylic, and after finding that it scratches too easily, ended up
>using the thinnest glass I could find -
>http://www.krupin.net/serendipity/uploads/pcb_making_exposure_frame.jpg
>
>It sounds to me that using thick glass would seriously slow down the
>exposure time, especially for people who are using a less powerful light
>than the one you have.
>
>Vlad
>--
>Vlad's shop
>http://www.krupin.net/serendipity/index.php?/categories/2-metalworking
>
>
>[Non-text portions of this message have been removed]
>
>
>
>
>
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>If Files or Photos are running short of space, post them here:
>http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
>Yahoo! Groups Links
>
>
>
>

> Doesn't glass (or at least most kinds of glass) tend to absorb UV rays? I
>
> was under the impression that this was the case. As a result I first
> tried
>
> using acrylic, and after finding that it scratches too easily, ended up
>
> using the thinnest glass I could find -
>
> http://www.krupin.net/serendipity/uploads/pcb_making_exposure_frame.jpg
>
>
> It sounds to me that using thick glass would seriously slow down the
>
> exposure time, especially for people who are using a less powerful light
>
> than the one you have.
>
>
> Vlad

> Doesn't glass (or at least most kinds of glass) tend to absorb UV

> was under the impression that this was the case. As a result I

> using acrylic, and after finding that it scratches too easily,

> using the thinnest glass I could find -
>

>
> It sounds to me that using thick glass would seriously slow down the
> exposure time, especially for people who are using a less powerful

----- Original Message -----
From: "Radra" <infositeus@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, February 23, 2006 5:47 AM
Subject: [Homebrew_PCBs] Re: Photolithography - resolution


> Just fabricated my first PCB today using the photolithography method;
> prior PCBs were made using the toner-transfer method. My 10 to 15
> mil tracks were faithfully produced. Experimented with 1 and 5 mil
> tracks and learned I could do 5 mils but not 1 mils. I believe this
> limit is related to the resolution of the artwork I am using. I draw
> the track pattern using AutoCAD. It is then printed onto laser-
> printer transparency film (CG 3300 by 3M) using my HP LaserJet 2200d
> at 1200 dpi and 180 lpi.
>
> When I examine the resulting transparency under a microscope, it
> becomes apparent the 1 mil line is poorly rendered. At this time, I
> do not know if the limiting factor is the printer or the film.
>
> Does anyone have any ideas/suggestions? One possibility of course is
> to have the artwork transparency professionally made.

Do you really mean 1 mil (0.001)?

Leon

> Lyman, congrats on your first photo-board.
>
>
> You didn't say what your exposure tool was; but at the
>
> 1-mil level, you may well be running into effects of poor
>
> collimation; as much as any other factor.

----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, February 23, 2006 10:15 AM
Subject: Re: [Homebrew_PCBs] Re: Re: Photolithography - resolution


> On Thu, 23 Feb 2006 09:09:15 +0100, Richard <metal@...> wrote:
>
>> Lyman, congrats on your first photo-board.
>>
>>
>> You didn't say what your exposure tool was; but at the
>>
>> 1-mil level, you may well be running into effects of poor
>>
>> collimation; as much as any other factor.
>
>
> Yea sure, making 1mil traces, that's 25um wide, a typical pcb has 35u of
> copper thickness.
> So anyone telling me he is making PCBs with traces that are actually
> narrower than they are high is either very, very good, or a liar. 'Cause
> without directional etching like used for ICs that's just not happening.
>
> I think industry standard is 2mil minimum, but that's on thinner copper
> and with spray etching.
>
> From my experience, anything below 6.66mil is unreliable due to
> underetching. And that's the same with toner transfer and photoprocess. 4
> or 5 mil traces i could believe with a well set-up etcher, but 1mil, come
> on! And it makes no difference if that is photoprocess or toner transfer,
> the underetching is getting you first with both methods.
>
> So, unless someone shows me a PCB that actually has 1mil traces _made_
> _at_ _home_ i'll just take this at joke value, because i've been there,
> tried that:

I think that the really fine-line stuff is made by copper deposition, not
etching.

Leon

> I think that the really fine-line stuff is made by copper deposition, not
>
> etching.
>
>
> Leon

----- Original Message -----
From: "Radra" <infositeus@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, February 23, 2006 5:22 PM
Subject: [Homebrew_PCBs] Re: Photolithography - resolution


> The purpose of my original post was to query the group regarding
> resolution limitations of the photolithography process. My attempts
> to fabricate a useable 1 mil (0.001 inch) track have proved
> unsuccessful leading me to ask "why"? So far I have received two
> comments (thank you): one related to collimation of the UV source and
> the other related to etching considerations.
>
> Let me provide a little more information regarding my goals and
> processes. My intent is to devise a simple "at-home" process which
> will produce PCBs with finer resolution and without the pin holes
> associated with the toner-transfer process. I am an RF engineer and
> need to produce good looking prototypes.
>
> I created a test pattern which I used to assist me in the development
> of the process. The pattern consists of 100, 50, 10, 5 , and 1 mil
> parallel lines and a grid made of 1 mil lines. My UV light source is
> a Blak-Ray B-100A long-wave source made by UVP. This source produces
> an intense spot beam. I position my artwork about 2 feet from the
> lamp and expose the dry-film PCB for 1 minute. Trial runs were made
> using exposure times between 10 seconds and 6 minutes; 1 minute
> proved to be satisfactory.
>
> My test runs demonstrated I could reliably produce 5 mil lines but
> not the 1 mil lines. Microscopic examination of the 1 mil line
> artwork revealed that the two parallel edges of the line tended to
> not have a clearly defined area between them. Thus when I used this
> artwork to expose the PCB, the resulting pattern on the PCB was not
> well defined prior to etching. It is then natural to wonder if my
> transparency artwork can be improved "at home" and, if so, will I be
> then able to fabricate a higher resolution product.
>
> Lastly, my goal is not to actually fabricate 1 mil lines as I don't
> need them. Instead my goal is to learn what can be reasonably
> accomplished "at home" and apply that knowledge to fabricate the best
> looking PCBs possible. So, setting aside etching considerations for
> the moment, my original question still stands, does anyone have
> suggestions regarding how I can improve the processes employed prior
> to etching?

I get better results with an inkjet printer (8 mil tracks without any
problems) than when I used to use a laser printer. The latter was rather
old, though, and only 600 dpi resolution. Best results are obtained with
photoplots, of course.

Leon

> Lastly, my goal is not to actually fabricate 1 mil lines as I don't
>
> need them. Instead my goal is to learn what can be reasonably
>
> accomplished "at home" and apply that knowledge to fabricate the best
>
> looking PCBs possible. So, setting aside etching considerations for
>
> the moment, my original question still stands, does anyone have
>
> suggestions regarding how I can improve the processes employed prior
>
> to etching?
>
>
> Lyman

> The purpose of my original post was to query the group regarding
> resolution limitations of the photolithography process. My attempts
> to fabricate a useable 1 mil (0.001 inch) track have proved
> unsuccessful leading me to ask "why"? So far I have received two
> comments (thank you): one related to collimation of the UV source and
> the other related to etching considerations.
>
> Let me provide a little more information regarding my goals and
> processes. My intent is to devise a simple "at-home" process which
> will produce PCBs with finer resolution and without the pin holes
> associated with the toner-transfer process. I am an RF engineer and
> need to produce good looking prototypes.

> I created a test pattern which I used to assist me in the development
> of the process. The pattern consists of 100, 50, 10, 5 , and 1 mil
> parallel lines and a grid made of 1 mil lines. My UV light source is
> a Blak-Ray B-100A long-wave source made by UVP. This source produces
> an intense spot beam. I position my artwork about 2 feet from the
> lamp and expose the dry-film PCB for 1 minute. Trial runs were made
> using exposure times between 10 seconds and 6 minutes; 1 minute
> proved to be satisfactory.
>
> My test runs demonstrated I could reliably produce 5 mil lines but
> not the 1 mil lines. Microscopic examination of the 1 mil line
> artwork revealed that the two parallel edges of the line tended to
> not have a clearly defined area between them. Thus when I used this
> artwork to expose the PCB, the resulting pattern on the PCB was not
> well defined prior to etching. It is then natural to wonder if my
> transparency artwork can be improved "at home" and, if so, will I be
> then able to fabricate a higher resolution product.
>
> Lastly, my goal is not to actually fabricate 1 mil lines as I don't
> need them. Instead my goal is to learn what can be reasonably
> accomplished "at home" and apply that knowledge to fabricate the best
> looking PCBs possible. So, setting aside etching considerations for
> the moment, my original question still stands, does anyone have
> suggestions regarding how I can improve the processes employed prior
> to etching?

----- Original Message -----
From: "Radra" <infositeus@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, February 24, 2006 5:23 PM
Subject: [Homebrew_PCBs] Re: Photolithography - resolution


> Have you had the opportunity to examine your artwork transparency
> (mask) using a microscope? I wonder if it is better than mine. Wish
> I had some way to take a photomicrograph so I could post a photo.
>
> I was having some difficulty during the developing process. Some
> areas where the resist was supposed to dissolve away were not
> becoming completely clean. Assumed it might be due to the dark areas
> of my mask not being sufficiently opaque to UV. The dark areas
> actually appear grey, not black, when held up to a light. So I
> overlaid two masks to increase effective opacity. Placed the toner
> side of one mask against the toner side of a mirror image mask. The
> down side of this technique is that the toner image is now 4 mils
> away from the PCB due to the transparency thickness which, as you
> observed, will degrade resolution; but the resulting PCB was
> acceptable. In retrospect, I now suspect I did not have to overlay
> the masks, but instead only needed to improve the developing process.
>
> So the question I now have is "Does an inkjet printer produce better
> masks than does a laserjet printer?".

It's a lot better than the laser printers I have. I haven't compared it with
anything expensive, though. The laser printing process is inherently
granular, with a lot of variation in the 'blobs' produced by the toner
particles. The sizes of inkjet droplets are much better controlled, I would
think.

Leon

----- Original Message -----
From: "Vlad Krupin" <vlad.cnc@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, February 24, 2006 5:42 PM
Subject: Re: [Homebrew_PCBs] Re: Photolithography - resolution


> FWIW,
>
> Recently I noticed that the toner in my laserjet printer is probably
> running
> low, so the images are not as dark as they used to be a few years ago. I
> took out the cartrige, gently tilted and shook it from side to side,
> cleaned
> the roller, put it back, and printed a blank page (shaking disturbs the
> toner so on the first page it sticks to places where it should not be).
> After that the next few pages come out blacker than before.
>
> This may not be your problem, and I should probably just buy a new
> cartrige,
> but I wanted to share this little observation with the rest of the group.
> It
> makes quite a difference on my printer, so it may help somebody else as
> well.

That's a well-known trick, I also used to do it at work whenever cartridges
were running out.

Leon

> Have you had the opportunity to examine your artwork transparency
> (mask) using a microscope? I wonder if it is better than mine. Wish
> I had some way to take a photomicrograph so I could post a photo.
>
> I was having some difficulty during the developing process. Some
> areas where the resist was supposed to dissolve away were not
> becoming completely clean. Assumed it might be due to the dark areas
> of my mask not being sufficiently opaque to UV. The dark areas
> actually appear grey, not black, when held up to a light. So I
> overlaid two masks to increase effective opacity. Placed the toner
> side of one mask against the toner side of a mirror image mask. The
> down side of this technique is that the toner image is now 4 mils
> away from the PCB due to the transparency thickness which, as you
> observed, will degrade resolution; but the resulting PCB was
> acceptable. In retrospect, I now suspect I did not have to overlay
> the masks, but instead only needed to improve the developing process.
>
> So the question I now have is "Does an inkjet printer produce better
> masks than does a laserjet printer?".

> > So the question I now have is "Does an inkjet printer produce

> > masks than does a laserjet printer?".
>
> Only if the inkjet transparency is decent stuff *and* the ink is

> with it *and* it's not a crappy printer.
>
> If the ink is incompatible, you usually get pinholing, slow drying,

> sometimes smudging. Crappy printers are slow drying, leave streaks,

> smudging anyway. Decent printers can be a cheap base model (like an

> stylus 400 color, long discontinued). I've found epsons better

> use piezo-mechanical ejectors on room-temperature ink, and the ink

> into the gelatine coating of epson transparencies which dries really

> Other slower-drying printers and non-genuine ink/film combinations

> give decent results, but you'll have to experiment to find the right

>
> Laser printers often give dark edges but not-very-dark interiors

> printing larger areas. The heat can deform the printout, depending

> what it's made of. Laser printouts are always grainier and can show

> pinholes if you change to a new cartridge with different toner.
>

>Have you had the opportunity to examine your artwork transparency
>mask) using a microscope? I wonder if it is better than mine. Wish
>I had some way to take a photomicrograph so I could post a photo.

>So the question I now have is "Does an inkjet printer produce better
>masks than does a laserjet printer?".