Photo-etch light source?

On Fri, 09 Mar 2007 13:03:44 GMT, NoSpam@daqarta.com (Bob Masta)
wrote:

>On Fri, 09 Mar 2007 14:53:15 +1100, Lionel <usenet@imagenoir.com>
[...]
>>Please note the comments about metering on white objects vs green,
>>etc, in the original post at that URL.
>
>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.

-- 
   W  "Some people are alive only because it is illegal to kill them."
 . | ,. w ,      
  \|/  \|/              Perna condita delenda est
---^----^---------------------------------------------------------------

On 9 Mar 2007 05:15:25 -0800, "sirkituk" <sirkituk@yahoo.co.uk> wrote:

>> > You're talking about the transparency? I hear that output from a printer
>> is
>> > good enough. No?
>
>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?

-- 
   W  "Some people are alive only because it is illegal to kill them."
 . | ,. w ,      
  \|/  \|/              Perna condita delenda est
---^----^---------------------------------------------------------------

> 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,
-- 
Al, the usual

Usual Suspect wrote:

>>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? 
>  
>
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

"Sergey Kubushin" <ksi@koi8.net> wrote in message 
news:45eba505$0$16391$88260bb3@free.teranews.com...
> In sci.electronics.misc Lionel <usenet@imagenoir.com> wrote:
>> On Sun, 04 Mar 2007 18:14:40 GMT, Usual Suspect <reply@thegroup.net>
>> wrote:
>
>>>MG Chemicals sells pre-sensitized copper-clad PCB blanks for use with 
>>>their
>>>exposure and etch kit. Pretty straightforward "print pattern on 
>>>transparency;
>>>place on PCB; expose to light; wash off exposed portion; etch" process.
>>>
>>>The "expose" part of this process consists of using MGC's "daylight"
>>>fluorescent lamp.
>>>
>>>If it's truly a "daylight" bulb, wouldn't direct sunlight work for this
>>>purpose?
>
>> Yes, but it's very hard to get an accurate exposure with sunlight.
>
>>> I presume this bulb is of a particular wavelength. What is it?
>>>
>>>Any other ideas to use this process to etch PCBs without their lamp?
>
>> I've heard that greenhouse fluorescent tubes (the kind used for
>> hydroponics) work okay, but I don't have any personal experience with
>> them.
>
> 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...
>
> ---
> ******************************************************************
> *  KSI@home    KOI8 Net  < >  The impossible we do immediately.  *
> *  Las Vegas   NV, USA   < >  Miracles require 24-hour notice.   *
> ******************************************************************
>
> -- 
> Posted via a free Usenet account from http://www.teranews.com
>
FWIW-
Some people just enjoy the challenge of re-inventing the wheel...
Jamie 

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.




"Jon Elson" <jmelson@artsci.wustl.edu> wrote in message
news:45F1E8E2.70307@artsci.wustl.edu...
>
>
> Usual Suspect wrote:
>
> >>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?
> >
> >
> 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
>
>

On Mar 9, 6:52 pm, Usual Suspect <r...@thegroup.net> wrote:
> > 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,
> --
> Al, the usual

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