Homebrew_PCBs

I can do 12/12 mil tracks, with 10 mils if necessary, using an old LaserJet
IIIp to produce the transparencies. I was wondering what is the best any of
you can do with a laser printer. I've heard of people getting down to 8 mils
with a better printer than mine, and it should be quite easy using
photo-reduction from a 4:1 master.

There is a PCB co. in the UK that offers 4 mil tracks as standard! I haven't
bothered to ask them about prices, though, as I'm sure I won't be able to
afford to use them.

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

>I can do 12/12 mil tracks, with 10 mils if necessary, using an old LaserJet
>IIIp to produce the transparencies. I was wondering what is the best any of
>you can do with a laser printer. I've heard of people getting down to 8 mils
>with a better printer than mine, and it should be quite easy using
>photo-reduction from a 4:1 master.

Leon,

I can do 8 mil - no problem - by directly printing onto transparency
paper (not using photo-reduction or such) using an older HP LaserJet
4P. This laser is having a 600 dpi resolution. I'm sure I could go
even finer since text that I print with a very small font even ends up
readable but so far never had the need for finer pitch artwork.

I either must be very lucky, or then other factors like the base
material and it's photosensitive layer, kind of transparency paper I
use, developper or etching may are also important. What surprizes me a
bit is to hear how much sucess in this area varies among people. Some
people only seem to get average results even if they use
professionally made photo films while others like me can do well with
just cheap transparency paper.

Markus

Leon,
If you use commercially pre-sensitized board material ( I recommended
Ocean State at http://www.oselectronics.com/ose_p78.htm good price )
developed in Lye solution.
Using HP Laserjet 1100 at 600 DPI with economy toner saving featured
turned OFF, and using Apollo CG7060 Transparencies I can do 5 mil any
time.
Using same printer with 3M G3300 it will do 10 mil all the time.
I seem to remember the LJIIIP did 300 dpi. I think you can still expect
10 mil.
Hans W

Leon Heller wrote:

> I can do 12/12 mil tracks, with 10 mils if necessary, using an old
> LaserJet
> IIIp to produce the transparencies. I was wondering what is the best
> any of
> you can do with a laser printer. I've heard of people getting down to
> 8 mils
> with a better printer than mine, and it should be quite easy using
> photo-reduction from a 4:1 master.
>
> There is a PCB co. in the UK that offers 4 mil tracks as standard! I
> haven't
> bothered to ask them about prices, though, as I'm sure I won't be able
> to
> afford to use them.
>
> Leon
> --
> Leon Heller, G1HSM
> leon_heller@...
> http://www.geocities.com/leon_heller
>
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[Non-text portions of this message have been removed]

>From: Markus Zingg <m.zingg@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Narrowest tracks?
>Date: Mon, 26 May 2003 14:41:16 +0200
>
> >I can do 12/12 mil tracks, with 10 mils if necessary, using an old
>LaserJet
> >IIIp to produce the transparencies. I was wondering what is the best any
>of
> >you can do with a laser printer. I've heard of people getting down to 8
>mils
> >with a better printer than mine, and it should be quite easy using
> >photo-reduction from a 4:1 master.
>
>Leon,
>
>I can do 8 mil - no problem - by directly printing onto transparency
>paper (not using photo-reduction or such) using an older HP LaserJet
>4P. This laser is having a 600 dpi resolution. I'm sure I could go
>even finer since text that I print with a very small font even ends up
>readable but so far never had the need for finer pitch artwork.
>
>I either must be very lucky, or then other factors like the base
>material and it's photosensitive layer, kind of transparency paper I
>use, developper or etching may are also important. What surprizes me a
>bit is to hear how much sucess in this area varies among people. Some
>people only seem to get average results even if they use
>professionally made photo films while others like me can do well with
>just cheap transparency paper.

I'm quite sure I could get 8 mils, with a better printer, as I can get 12
reliably even with tracing paper.

I think a lot of people have problems because they have the artwork/PCB too
close to the UV source. The exposure might be nice and short but the
definition and contrast are often poor. Someone I know just can't get good
results. He's joked about coming over to the UK (from the US) to see how I
do it.

Leon
--
Leon Heller, G1HSM Tel: +44 1424 423947
Email:leon_heller@...
My web page: http://www.geocities.com/leon_heller

_________________________________________________________________
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Hello all,
I presume from the replies so far, all respondents use photo-resists. I have these questions.

What brand?
What type? liquid or dry film
What polarity? positive or negative.

Many thanks in anticipation
John C

>I'm quite sure I could get 8 mils, with a better printer, as I can get 12
>reliably even with tracing paper.

Of course, it works for me also.

>I think a lot of people have problems because they have the artwork/PCB too
>close to the UV source. The exposure might be nice and short but the
>definition and contrast are often poor. Someone I know just can't get good
>results. He's joked about coming over to the UK (from the US) to see how I
>do it.

Hmmm, I have a picture online of my exposing unit which is a Scanner
housing with UV tubes built in. The picture showes the opened unit and
there you can see that the tubes are relatively close too....

http://www.myhome.ch/mzingg/pcbstuff/img_0005.jpg

Markus

>From: "John Craddock" <John.Craddock@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: <Homebrew_PCBs@yahoogroups.com>
>Subject: RE: [Homebrew_PCBs] Narrowest tracks?
>Date: Mon, 26 May 2003 23:30:55 +1000
>
>Hello all,
>I presume from the replies so far, all respondents use photo-resists. I
>have these questions.
>
>What brand?
>What type? liquid or dry film

I buy my PCB material ready coated with positive resist, supplied by Mega
Electronics, UK. I think it is roller applied, according to the description
- 5 micron thick - then high-temp. cured.

>What polarity? positive or negative.

Positive. I develop in NaOH.

Leon
--
Leon Heller, G1HSM Tel: +44 1424 423947
Email:leon_heller@...
My web page: http://www.geocities.com/leon_heller

_________________________________________________________________
On the move? Get Hotmail on your mobile phone http://www.msn.co.uk/msnmobile

>From: Markus Zingg <m.zingg@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Narrowest tracks?
>Date: Mon, 26 May 2003 15:45:18 +0200
>
> >I'm quite sure I could get 8 mils, with a better printer, as I can get 12
> >reliably even with tracing paper.
>
>Of course, it works for me also.
>
> >I think a lot of people have problems because they have the artwork/PCB
>too
> >close to the UV source. The exposure might be nice and short but the
> >definition and contrast are often poor. Someone I know just can't get
>good
> >results. He's joked about coming over to the UK (from the US) to see how
>I
> >do it.
>
>Hmmm, I have a picture online of my exposing unit which is a Scanner
>housing with UV tubes built in. The picture showes the opened unit and
>there you can see that the tubes are relatively close too....

Similar to mine, except you have *lots* more tubes and mine is made
(crudely) from MDF. 8-)

My tubes (I only have 2) are about 13.5 cms from the glass and about 10 cms
apart. Exposure is 13 minutes. I keep meaning to add a third tube in the
middle and use curved reflectors and a sort of grid for collimation.

Leon
--
Leon Heller, G1HSM Tel: +44 1424 423947
Email:leon_heller@...
My web page: http://www.geocities.com/leon_heller

_________________________________________________________________
Get Hotmail on your mobile phone http://www.msn.co.uk/msnmobile

1) I use direct toner to hot foil. I use HP LaserJet 6L, works at
either 300 or 600 dpi.

2)Flat hot press to PCB. I was lucky enough to have one around, works
much better than an iron. Better, more consitant results.

3)etch in ferric chloride. I have Ammonium Persulphate, but I want to
finish using all the Ferric fist (its taking a long time).

I get 10 thou lines (10mil) without problem. Large surfaces give me a
bit of problem, but easy to fix. I could probably get 5mils, I just
don't need it, yet.

Look for my PCP photo (scan) in the "Files" folder, maybe today.

John Myszkowski...
==============================


--- In Homebrew_PCBs@yahoogroups.com, "John Craddock"
<John.Craddock@x> wrote:

> Hello all,
> I presume from the replies so far, all respondents use photo-

resists. I have these questions.

>
> What brand?
> What type? liquid or dry film
> What polarity? positive or negative.
>
> Many thanks in anticipation
> John C

>>Hmmm, I have a picture online of my exposing unit which is a Scanner
>>housing with UV tubes built in. The picture showes the opened unit and
>>there you can see that the tubes are relatively close too....
>
>Similar to mine, except you have *lots* more tubes and mine is made
>(crudely) from MDF. 8-)
>
>My tubes (I only have 2) are about 13.5 cms from the glass and about 10 cms
>apart. Exposure is 13 minutes. I keep meaning to add a third tube in the
>middle and use curved reflectors and a sort of grid for collimation.

The picture maybe does not show it clearly, but the tubes there are
farily close to the glass. I'm not at home at the moment to measure,
but out of my memory I'd say it's around 4 cm. Exposure time with the
precoated material (I asume something similar to what you use) is 90
seconds.

I could get the scanner housing for cheap from a loca dealer (was a
scanner where the software and docs got lost). The tubes are from a
Braun face browner unit.

Since I soon will have my plating trhough station ready I will switch
to photo resist ( I have it already ) and I was told that by using it
exposure time dropps significantly and becomes much less critical also
- well, let's see...

Markus

About the photos...

The Bottom (copper) side shows an UN-retouched process.
I printed the PCB tracks on the hot stamp foil (back side of it)
using my HP LaserJet 6L (any laser will do)
I placed the foil down on the (cleaned) PCB copper.
Pressed with the hot press.
Peeled the foil off.
Etched.
Drilled.
Cleaned off the toner and foil residue with acetone (works fastest,
but very dangerous chemical, use extreme caution). You can see the
black streaks left by the dissolved toner. It can be cleaned off, but
I just wanted to do it quickly.
Scanned it.
Posted it here.

The TOP side shows the component layout.
Again, it is unretouched, so it can be done much better if more care
is given.
I printed the component layout (reverse) on the back side of the hot
stamp foil.
PLaced it on the top side of the etched and drilled PCB.
Alignment or clarity was not important, and so it shows.

Interesting factoids...
1)The "copyright" notice on the PCB is written in 3mil lines. It
shows pretty well. I think it shows that very thin lines are quite
possible.

2)lines can become thick when pressure is increased too much, as
evident in the top/left quadrant of the copper side.


John Myszkowski...
========================


--- In Homebrew_PCBs@yahoogroups.com, "John Myszkowski"
<myszka_us2000@y...> wrote:

> 1) I use direct toner to hot foil. I use HP LaserJet 6L, works at
> either 300 or 600 dpi.
>
> 2)Flat hot press to PCB. I was lucky enough to have one around,

works

> much better than an iron. Better, more consitant results.
>
> 3)etch in ferric chloride. I have Ammonium Persulphate, but I want

to

> finish using all the Ferric fist (its taking a long time).
>
> I get 10 thou lines (10mil) without problem. Large surfaces give me

a

> bit of problem, but easy to fix. I could probably get 5mils, I just
> don't need it, yet.
>
> Look for my PCP photo (scan) in the "Files" folder, maybe today.
>
> John Myszkowski...
> ==============================
>
>