Photo-etch light source?

[Bob Masta]

Safety reminder: If you use Xylene don't forget that this liquid is as
flammable as gasoline. Vapors of xylene from an open container or an
evaporating source can crawl invisibly and without detection of it's
odor to an ignition point (pilot light, static discharge, electric range
etc.)

Xylene should be used in a well-ventilated area nowhere near any flame
or possible spark.

.... And if you manage to avoid explosions, you are not out of
the woods yet: Last time I checked, xylene was a pretty
nasty carcinogen.

Best regards,


Bob Masta

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!

 

[sirkituk]

Time depends on strength of developer, temperature and speed of the
resist.

I use sodium hydroxide solution to develop and a brush to speed the
process.

Yes.Beware of laser printing onto acetate sheet it can melt the sheet
and wreck the printer.
I use good quality tracing paper and find it works well with both
laser printers and highest density ink jet printers.

Regards sirkituk
www.geocities.com/sirkituk.htm

 

[Lionel]

The problem with this approach (regarding the original photo-etch
topic in the subject line) is that it only applies to visible light,
whereas photo-resist is sensitive to UV, which is greatly
reduced by camera lenses.

So, you can't use this to make any sort of absolute measurement
of UV levels, but if you have a source that emits a broad spectrum
(like a tanning lamp) such that you can get a reading on the meter,
then it would probably be reasonable to assume that everything
scales properly. Thus, if you use that same source at a different
distance, the camera meter could tell you the *change* in
exposure.

Absolutely true, because normal lenses block UV. However, one trick
that would get around that would be to put a sheet of fluorescent
material in place of your PCB, & meter off the visible light it
creates from the UV. I'd suggest a card painted with fluorescent green
poster paint.

 

[Lionel]

Yes.Beware of laser printing onto acetate sheet it can melt the sheet
and wreck the printer.

Yes. You need to use acetate sheets that are specifically labelled as
being suitable for photocopiers or laser printers. They are perfectly
safe for this purpose. Ones intended for inkjet ARE NOT safe in
lasers. Don't take the salesperson's word for it, check the label on
the box yourself.

I use good quality tracing paper and find it works well with both
laser printers and highest density ink jet printers.

I've heard others say that too, but haven't tried it myself. Can you
recommend any specific brands?

 

[Usual Suspect]

Don't you just submerge it and brush it and watch when it's all gone

(all the exposed part) then take it out? Or am I missing something?

I meant to say "submerge it in developer..."

I use sodium hydroxide solution to develop and a brush to speed the
process.

The MG Chemicals demo video
< http://www.mgchemicals.com/downloads/media/photofablarge.wmv>
shows that there is a developer solution into which the exposed PCB needs to
be developed. They just use a foam brush to brush off the exposed resist.
Looks like a pretty quick process.

Are you using NaOH in place of the developer? To supplement the developer? Or
are you using it as a wash to remove the unneeded (exposed) resist after
development?

And are you using MG Chem. PCBs? (Just want to understand what chems work
with what boards...)

I use good quality tracing paper and find it works well with both
laser printers and highest density ink jet printers.

A great idea.

Thanks,

 

[Jon Elson]

I meant to say "submerge it in developer..."




The MG Chemicals demo video
< http://www.mgchemicals.com/downloads/media/photofablarge.wmv>
shows that there is a developer solution into which the exposed PCB needs to
be developed. They just use a foam brush to brush off the exposed resist.
Looks like a pretty quick process.

Are you using NaOH in place of the developer? To supplement the developer? Or
are you using it as a wash to remove the unneeded (exposed) resist after
development?

The Xylene stuff is the developer for KPR type resist. Awful stuff, I
stopped using
it 30 years ago. The NaCO3 (Sodium Carbonate) is used for Riston type
dry film
resist that is thermally laminated to the board. NaOH is the resist
stripper for after
the etching is done. At least, those are the materials I am familiar with.
Jon

 

[Jamie]

I wonder guys, why wouldn't you just use a proper long-wave UV bulb? They
are aplenty and dirt cheap... Any T8 BL or BLB works like a charm, doesn't
require anything but regular fluorescent ballast to run and produces that
very sub-400nm lightwave required for exposure...

Why are you trying anything but a proper tool? Am I missing something?

Just FUI -- that magical MGC lamp is just a 15 Watt T8 BL bulb in a
regular
fluorescent fixture...

---
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FWIW-
Some people just enjoy the challenge of re-inventing the wheel...
Jamie

 

[Guest]

yes, the xylene type is quite noxious and requires adequate ventilation, (im
sure its NOT a green process at any rate!) and the stuff is deadly
flammable too! gloved hands required too.

it was what i used from my years at a tech in a small company, so i had a
ready supply of surplus stuff to use. me a cheapie!

the new sodium hydroxide method seems adequate and just as reliable for the
few times i used it. and u can use the was repeatedly and the use it to
strip floor wax off the office tile floors! ) same stuff in
EasyClean Oven cleaner, cuts grease like lightning! a fairly common
chemical for many uses.

yes, acetate is better than running mylar thru a 450 degree printer fuser ,
i just never got it stuck or whatever happens i guess. best to use the
recommneded transparency media recommended by the laser printer
manufacturer.

 

[sirkituk]

I meant to say "submerge it in developer..."


The MG Chemicals demo video
<http://www.mgchemicals.com/downloads/media/photofablarge.wmv>
shows that there is a developer solution into which the exposed PCB needs to
be developed. They just use a foam brush to brush off the exposed resist.
Looks like a pretty quick process.

Are you using NaOH in place of the developer? To supplement the developer? Or
are you using it as a wash to remove the unneeded (exposed) resist after
development?

And are you using MG Chem. PCBs? (Just want to understand what chems work
with what boards...)


A great idea.

Thanks,

I live and work in UK
I use what I refer to as standard PCB board (purchased from Rapid
Electronics) They have a website catalogue you could check for more
details
http://www.rapidelectronics.co.uk
With these boards NaOH is the developer
The unexposed resist can be removed with alcohol (methylated spirits)
but since the heat of a soldering iron strips it as you solder that's
not really needed and it does protect the board from oxidation prior
to soldering
Regards sirkituk
www.geocities.com/sirkituk.htm