Homebrew_PCBs

Having been given several flat bed scanners I am finally going to build an exposure box and was thinking about the light source.

The boards could be as big as 5 x 5 inches down to .75 x .75 inches.

I look at the multi-led solutions and it seems like the non-collimated light might be an issue.

The nail dryer bulb solution might be slightly better but maybe not.

A single point source such as a single high powered led by definition would not be collimated but at least it would be a single point source. But then one has to deal with uneven exposure from viewing angle issues.

Any thoughts based on your experiences would be appreciated, including "Your are over thinking this! Just build the d..n box.".

Thanks,
Arvid

> arvidj01 wrote:
>
> <SNIP>
>
> Any thoughts based on your experiences would
> be appreciated, including "Your are over
> thinking this! Just build the d..n box.".

If your only looking for 8/8 rules and
have a good phototool in a vacuum frame
then collimation is not an issue.

I had one of those kinsten boxes that has
woefully large amounts of side light and
8/8 was fine on it.

It's an issue for extremely fine tracks.

You can always use 4 inch drain pipe, cut in half along the longitude, and
lined with mirror plastic, plus "egg crate" for fluorescent fittings. Three
or Four UV tubes will then do the trick for you

Regards

Frank

From: arvidj01 <arvidj@...>
Reply-To: <Homebrew_PCBs@yahoogroups.com>
Date: Saturday, 6 July 2013 3:05 PM
To: <Homebrew_PCBs@yahoogroups.com>
Subject: [Homebrew_PCBs] For a DIY exposure box ... is collimated light an
issue?

> Having been given several flat bed scanners I am finally going to build an
> exposure box and was thinking about the light source.
>
> The boards could be as big as 5 x 5 inches down to .75 x .75 inches.
>
> I look at the multi-led solutions and it seems like the non-collimated light
> might be an issue.
>
> The nail dryer bulb solution might be slightly better but maybe not.
>
> A single point source such as a single high powered led by definition would
> not be collimated but at least it would be a single point source. But then one
> has to deal with uneven exposure from viewing angle issues.
>
> Any thoughts based on your experiences would be appreciated, including "Your
> are over thinking this! Just build the d..n box.".
>
> Thanks,
> Arvid
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
>

[Non-text portions of this message have been removed]

On 06/07/13 15:05, arvidj01 wrote:

>
>
> Any thoughts based on your experiences would be appreciated, including
> "Your are over thinking this! Just build the d..n box.".
>

For hobby purposes, this.

If you use LEDs, just do a quick check that your led spacing and
distance to your artwork from the leds does not introduce dead spots,
that is, make sure the viewing angles of adjacent LEDs overlap at or
just before the artwork.

Dead spots will make the box useless for everything, while poor/no
collimation won't have an effect unless you're really pushing the
boundaries of hobby exposure in my opinion.




[Non-text portions of this message have been removed]

> Frank Collingwood wrote:
>
> You can always use 4 inch drain pipe,
> cut in half along the longitude, and
> lined with mirror plastic, plus "egg
> crate" for fluorescent fittings. Three
> or Four UV tubes will then do the
> trick for you

I agree with Frank wholeheartedly

https://www.thinktink.com/stack/volumes/voliii/equipment/uvlamp/uvlamp.htm

https://www.thinktink.com/stack/volumes/voliii/equipment/uvlamp/uvlamp04.htm

--- In Homebrew_PCBs@yahoogroups.com, "cunningfellow" <andrewm1973@...> wrote:

>
>
>
> > Frank Collingwood wrote:
> >
> > You can always use 4 inch drain pipe,
> > cut in half along the longitude, and
> > lined with mirror plastic, plus "egg
> > crate" for fluorescent fittings. Three
> > or Four UV tubes will then do the
> > trick for you
>
> I agree with Frank wholeheartedly
>
> https://www.thinktink.com/stack/volumes/voliii/equipment/uvlamp/uvlamp.htm
>
> https://www.thinktink.com/stack/volumes/voliii/equipment/uvlamp/uvlamp04.htm
>

Thanks for the responses.

I was impressed by the think and tinker solution but was turned off by the expense of the lights and fixtures and the size. Based on the diagram with the collimator it must be at least 18 inches tall. I understand why it needs to be that tall but can not afford the space in my small workshop.

--- In Homebrew_PCBs@yahoogroups.com, James <bitsyboffin@...> wrote:

>
> On 06/07/13 15:05, arvidj01 wrote:
> >
> >
> > Any thoughts based on your experiences would be appreciated, including
> > "Your are over thinking this! Just build the d..n box.".
> >
>
> For hobby purposes, this.
>
> If you use LEDs, just do a quick check that your led spacing and
> distance to your artwork from the leds does not introduce dead spots,
> that is, make sure the viewing angles of adjacent LEDs overlap at or
> just before the artwork.
>
> Dead spots will make the box useless for everything, while poor/no
> collimation won't have an effect unless you're really pushing the
> boundaries of hobby exposure in my opinion.

The UV LED's on eBay seem to come in two flavors:

narrow angle, about 20 to 25 degrees

wide angle, about 150 to 160 degrees

It would seem like the wide angle version would mitigate the dead spot issue at the expense of needing more LED's to make up for the lack of focus ... no pun intended ... of the energy by the wide angle.

My thought is that a large number of wide angle LED's would provide a very even ... but also extremely non-collimated ... UV source.

On 07/06/2013 06:53 PM, brane2 wrote:

> I've just finished purchasing some of the material for our first
> non-improvised lamp.
>
> I plan to use Osram's bactericidal fluo lamp Puritec 15W:
>
> http://www.osram.com/appsinfo/pdc/pdf.do?cid=GPS01_1028570&mpid=ZMP_1008467&vid=EU_ALL_eCat&lid=EN
>
> I plan to use 6 of them in front of simple reflector, made of 1-2mm
> aluminuim sheet, covered with adhesive mirror foil ( as used in
> aquariums etc). Metal sheet will have edges ( like last 10 cm or so on
> each side) bent at an angle 45° and I plan to kill non-vertical rays
> with black cardboard mesh in front of reflector.
>
> Flo lamps are EUR9/pc, electronic ballasts are EUR15 or so. I planned to
> repurpose PC's PSU for that and ouple other things, but colleague has
> already brought a couple of them with lamps, so I might just buy a
> couple more and use them instead...
>

I would suggest not to use the lamps that you specified.
UVC is not the wavelength band that is "the best solution" for PCB exposure.
Try to find lamps that are intendend for "reprophotography", Philips
carries some of these, that are in UVA wavelength band.

--
Best Regards,
Q Systems
Zoran A. Šćepanović
zastos@...
Skype: zoran.a.scepanovic
http://zastos.com
+381 63 609-993

-..-
Time flies like an arrow, fruit flies like a banana.

I've just finished purchasing some of the material for our first
non-improvised lamp.

I plan to use Osram's bactericidal fluo lamp Puritec 15W:

http://www.osram.com/appsinfo/pdc/pdf.do?cid=GPS01_1028570&mpid=ZMP_1008467&vid=EU_ALL_eCat&lid=EN

I plan to use 6 of them in front of simple reflector, made of 1-2mm
aluminuim sheet, covered with adhesive mirror foil ( as used in
aquariums etc). Metal sheet will have edges ( like last 10 cm or so on
each side) bent at an angle 45° and I plan to kill non-vertical rays
with black cardboard mesh in front of reflector.

Flo lamps are EUR9/pc, electronic ballasts are EUR15 or so. I planned to
repurpose PC's PSU for that and ouple other things, but colleague has
already brought a couple of them with lamps, so I might just buy a
couple more and use them instead...








Dne 06. 07. 2013 14:35, pis(e arvidj01:

>
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>, James <bitsyboffin@...> wrote:
> >
> > On 06/07/13 15:05, arvidj01 wrote:
> > >
> > >
> > > Any thoughts based on your experiences would be appreciated,
> including
> > > "Your are over thinking this! Just build the d..n box.".
> > >
> >
> > For hobby purposes, this.
> >
> > If you use LEDs, just do a quick check that your led spacing and
> > distance to your artwork from the leds does not introduce dead spots,
> > that is, make sure the viewing angles of adjacent LEDs overlap at or
> > just before the artwork.
> >
> > Dead spots will make the box useless for everything, while poor/no
> > collimation won't have an effect unless you're really pushing the
> > boundaries of hobby exposure in my opinion.
>
> The UV LED's on eBay seem to come in two flavors:
>
> narrow angle, about 20 to 25 degrees
>
> wide angle, about 150 to 160 degrees
>
> It would seem like the wide angle version would mitigate the dead spot
> issue at the expense of needing more LED's to make up for the lack of
> focus ... no pun intended ... of the energy by the wide angle.
>
> My thought is that a large number of wide angle LED's would provide a
> very even ... but also extremely non-collimated ... UV source.
>
>

[Non-text portions of this message have been removed]

On 07/06/2013 08:57 PM, brane2 wrote:

> Dne 06. 07. 2013 16:10, piše "Zoran A. Šćepanović":
>>
>> On 07/06/2013 06:53 PM, brane2 wrote:
>>> I've just finished purchasing some of the material for our first
>>> non-improvised lamp.
>>>
>>> I plan to use Osram's bactericidal fluo lamp Puritec 15W:
>>
>>>
>>
>> I would suggest not to use the lamps that you specified.
>> UVC is not the wavelength band that is "the best solution" for PCB
>> exposure.
>> Try to find lamps that are intendend for "reprophotography", Philips
>> carries some of these, that are in UVA wavelength band.
>>
> I already have two of those on cobbled up reflector. They are not as
> good as low pressure Hg, but they are not that much worse. And they work
> simply phenomenal as EPROM erasers.
>
> I will check those Phips lamps out, but since Osrams work well enough
> for me and I have local source handy and already have the lamps, I plan
> to deploy these first.
>
> Thanks for suggestion.
>

Watch your eyes, UVC is harmfull :-)

--
Best Regards,
Q Systems
Zoran A. Šćepanović
zastos@...
Skype: zoran.a.scepanovic
http://zastos.com
+381 63 609-993

-..-
Watch this space.

On Sat, 06 Jul 2013 18:57:55 +0000, you wrote:

>Dne 06. 07. 2013 16:10, piše "Zoran A. Š?epanovi?":
>>
>> On 07/06/2013 06:53 PM, brane2 wrote:
>> > I've just finished purchasing some of the material for our first
>> > non-improvised lamp.
>> >
>> > I plan to use Osram's bactericidal fluo lamp Puritec 15W:
>>
>> >
>>
>> I would suggest not to use the lamps that you specified.
>> UVC is not the wavelength band that is "the best solution" for PCB
>> exposure.
>> Try to find lamps that are intendend for "reprophotography", Philips
>> carries some of these, that are in UVA wavelength band.
>>
>I already have two of those on cobbled up reflector. They are not as
>good as low pressure Hg, but they are not that much worse. And they work
>simply phenomenal as EPROM erasers.

There are reasons why EPROM erasers have a kill switch on the lights
when the enclosure is opened. You can seriously damage your sight
with these lamps, since they are made to be germicidal.

Please read up on them if you haven't, and observe all the safety
precautions.

Harvey

>
>I will check those Phips lamps out, but since Osrams work well enough
>for me and I have local source handy and already have the lamps, I plan
>to deploy these first.
>
>Thanks for suggestion.
>
>> --
>> Best Regards,
>> Q Systems
>> Zoran A. Š?epanovi?
>> zastos@... <mailto:zastos%40gmail.com>
>> Skype: zoran.a.scepanovic
>> http://zastos.com
>> +381 63 609-993
>>
>> -..-
>> Time flies like an arrow, fruit flies like a banana.
>>
>>
>
>
>
>[Non-text portions of this message have been removed]

Dne 06. 07. 2013 16:10, piše "Zoran A. Šćepanović":

>
> On 07/06/2013 06:53 PM, brane2 wrote:
> > I've just finished purchasing some of the material for our first
> > non-improvised lamp.
> >
> > I plan to use Osram's bactericidal fluo lamp Puritec 15W:
>
> >
>
> I would suggest not to use the lamps that you specified.
> UVC is not the wavelength band that is "the best solution" for PCB
> exposure.
> Try to find lamps that are intendend for "reprophotography", Philips
> carries some of these, that are in UVA wavelength band.
>

I already have two of those on cobbled up reflector. They are not as
good as low pressure Hg, but they are not that much worse. And they work
simply phenomenal as EPROM erasers.

I will check those Phips lamps out, but since Osrams work well enough
for me and I have local source handy and already have the lamps, I plan
to deploy these first.

Thanks for suggestion.

> --
> Best Regards,
> Q Systems
> Zoran A. Šćepanović
> zastos@... <mailto:zastos%40gmail.com>
> Skype: zoran.a.scepanovic
> http://zastos.com
> +381 63 609-993
>
> -..-
> Time flies like an arrow, fruit flies like a banana.
>
>

[Non-text portions of this message have been removed]

If you are going to insist on building a device with lamps that are a danger to view, then you should definitely consider the idea that this device may not always be in your possession or control. It could fall into other hands by any number of circumstances. I would highly urge that you take precautionS from the design stage and implement them in the construction BEFORE the device is operational. I deliberately used a capitol "S" to emphasize that more than one precaution should be taken.

As a minimum I would suggest that:

1. The light be completely contained with zero leakage when it is on.

2. There should be an automatic kill switch when the device is opened and the light is exposed.

3. There should be a plainly worded warning permanently affixed to the exterior of the device. It should state the nature of the danger AND what precautions should be taken.

I am not an expert on these particular devices, but I do have a fairly good knowledge of optics and have made PCBs using a simple contact printing frame and an external light source a couple of feet away. I personally think that unless you are presently making boards with very fine features AND are having problems with the process that you can attribute to uncollimated light, then this whole subject is just a waste of time. I doubt that very many home or small scale industrial makers of PCBs have anything to worry about here.

Make or buy a simple contact printing frame. Use an external light that is about 1.5 to 2.5 feet away. Do not move the light or frame while exposing the board. This should work in 99.999% of all cases. Then, even if you are having a problem, I would suspect other sources of trouble first. Or use the old standby, sun light. That is very collimated: probably more so than any device you will construct.

Oh, and do be sure that the emulsion or printed (ink/toner) side of your negative/positive is the one in contact with the board.

Paul A.

--- In Homebrew_PCBs@yahoogroups.com, Harvey White <madyn@...> wrote:
>
> On Sat, 06 Jul 2013 18:57:55 +0000, you wrote:
>

...<SNIP>...


>
> There are reasons why EPROM erasers have a kill switch on the lights
> when the enclosure is opened. You can seriously damage your sight
> with these lamps, since they are made to be germicidal.
>
> Please read up on them if you haven't, and observe all the safety
> precautions.
>
> Harvey
>
>
>

...<SNIP>...

> >[Non-text portions of this message have been removed]
>

On Mon, Jul 8, 2013 at 4:19 AM, brane2 <brankob@...> wrote:

> Dne 07. 07. 2013 15:37, pis(e epa_iii:
>>
>> consider the idea that this device may not always be in your possession or control.
>
> Chill out a little FFS...

Some people live in very litigious societies. However well meaning
you are, some asshole will always be looking for a reason to sue you,
and scumbag lawyers are altogether too happy to oblige. Safety
mechanisms are a way to be seen to take the safety issue seriously,
which can be a legal defence.

Also, such a box may end up in the hands of minors, or people who just
don't realise the danger. Here's an example of how 4 people
(including a 6 year-old child) died, as a result of not knowing of the
dangers of the pretty glowing blue stuff they'd found:

http://en.wikipedia.org/wiki/Goi%C3%A2nia_accident

Would be a shame if some young boy or girl lost their eyesight just
for want of a safety switch...

Mitch.

I doubt that for home use, such exigencies are necessary.

I know that my welders are dangerous. My rotary phase converter is dangerous. My 80 gallon air compressor is dangerous. My many, many edged tools are dangerous.

I do not let children or idiots play in my shop. Period. If I did, they'd likely find the documentation and get paper cuts, or drop a binder on their foot. And anyway -- all warning signage left at its own value -- how many pre-grade school children or idiots do you know who can read? And I include about half of Congress in the latter category....

I do not waste my time creating and deploying warning labels on my stuff unless it's really, REALLY dangerous.

Although sometimes I put the following label on the bottom of car batteries:

"Open other end."

73
Jim N6OTQ

>________________________________
> From: brane2 <brankob@...>
>To: Homebrew_PCBs@yahoogroups.com
>Sent: Sunday, July 7, 2013 2:03 PM
>Subject: Re: [Homebrew_PCBs] Re: For a DIY exposure box ... is collimated light an issue?
>
>
>Dne 07. 07. 2013 18:53, piše brane2:
>>
>> Fair enough, but in such environments I wouldn't act on your advice
>> alone, I would check legal requirements first. One can not deal with
>> such things on advice of random legal layman.
>>
>
>I didn't mean to be rude here, just to say that satisfying legal
>constraints usually needs knowing _exact_ requirements and just
>plopping _somewhere_ _some_ text is not enough...
>

[Non-text portions of this message have been removed]

I'm sure that caesium source had a fair number of warning signs.......

That said, it doesn't cost anything to put a warning on the exposure
box, to remind yourself as much as to remind anyone else.

ST

On Sun, Jul 7, 2013 at 7:34 PM, Jim <n6otq@...> wrote:
> I doubt that for home use, such exigencies are necessary.
>
> I know that my welders are dangerous. My rotary phase converter is dangerous. My 80 gallon air compressor is dangerous. My many, many edged tools are dangerous.
>
> I do not let children or idiots play in my shop. Period. If I did, they'd likely find the documentation and get paper cuts, or drop a binder on their foot. And anyway -- all warning signage left at its own value -- how many pre-grade school children or idiots do you know who can read? And I include about half of Congress in the latter category....
>
> I do not waste my time creating and deploying warning labels on my stuff unless it's really, REALLY dangerous.
>
> Although sometimes I put the following label on the bottom of car batteries:
>
> "Open other end."
>
> 73
> Jim N6OTQ
>

We seem to have strayed from the intent of my original question.

Thanks to those that offered advice. I'm planning on an LED solution with wide angle 120 to 140 degree flat top LED's to mitigate any hotspot issues and will assume the total lack of collimated light will not be an issue.

This is based on my thought that "consistently wrong everywhere will be easier to work with than 100% right in some places but way over and way under in others".

If anyone would like to advise against that and recommend that I use the narrow angle 20 to 25 degree round top LED's please let me know.

Thanks,
Arvid

--- In Homebrew_PCBs@yahoogroups.com, "arvidj01" <arvidj@...> wrote:
>
> Having been given several flat bed scanners I am finally going to build an exposure box and was thinking about the light source.
>
> The boards could be as big as 5 x 5 inches down to .75 x .75 inches.
>
> I look at the multi-led solutions and it seems like the non-collimated light might be an issue.
>
> The nail dryer bulb solution might be slightly better but maybe not.
>
> A single point source such as a single high powered led by definition would not be collimated but at least it would be a single point source. But then one has to deal with uneven exposure from viewing angle issues.
>
> Any thoughts based on your experiences would be appreciated, including "Your are over thinking this! Just build the d..n box.".
>
> Thanks,
> Arvid
>

On Mon, Jul 8, 2013 at 4:11 AM, arvidj01 <arvidj@...> wrote:

> We seem to have strayed from the intent of my original question.
>
> Thanks to those that offered advice. I'm planning on an LED solution with wide angle

I used the rounded ones:

http://capnstech.blogspot.com/2011/05/playpause-making-pcbs-at-home.html

Works fine for me.

(Admittedly my system is quite ghetto, but it will do 8/8mil reliably)

If I had to do it again, I'd use SMT LEDs.

Mitch.

Of course. I was thinking about twelve inches of lead just for an outer
part of the shield. Im kind of lingering between Uranium and
Kurchatovium for inner part.

On a related note, I never jerk off outside of hazmat suit. Better safe
than sorry.

Chill out a little FFS...













Dne 07. 07. 2013 15:37, pis(e epa_iii:

>
> If you are going to insist on building a device with lamps that are a
> danger to view, then you should definitely consider the idea that this
> device may not always be in your possession or control. It could fall
> into other hands by any number of circumstances. I would highly urge
> that you take precautionS from the design stage and implement them in
> the construction BEFORE the device is operational. I deliberately used
> a capitol "S" to emphasize that more than one precaution should be taken.
>
> As a minimum I would suggest that:
>
> 1. The light be completely contained with zero leakage when it is on.
>
> 2. There should be an automatic kill switch when the device is opened
> and the light is exposed.
>
> 3. There should be a plainly worded warning permanently affixed to the
> exterior of the device. It should state the nature of the danger AND
> what precautions should be taken.
>
> I am not an expert on these particular devices, but I do have a fairly
> good knowledge of optics and have made PCBs using a simple contact
> printing frame and an external light source a couple of feet away. I
> personally think that unless you are presently making boards with very
> fine features AND are having problems with the process that you can
> attribute to uncollimated light, then this whole subject is just a
> waste of time. I doubt that very many home or small scale industrial
> makers of PCBs have anything to worry about here.
>
> Make or buy a simple contact printing frame. Use an external light
> that is about 1.5 to 2.5 feet away. Do not move the light or frame
> while exposing the board. This should work in 99.999% of all cases.
> Then, even if you are having a problem, I would suspect other sources
> of trouble first. Or use the old standby, sun light. That is very
> collimated: probably more so than any device you will construct.
>
> Oh, and do be sure that the emulsion or printed (ink/toner) side of
> your negative/positive is the one in contact with the board.
>
> Paul A.
>
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>, Harvey White <madyn@...> wrote:
> >
> > On Sat, 06 Jul 2013 18:57:55 +0000, you wrote:
> >
>
> ...<SNIP>...
>
> >
> > There are reasons why EPROM erasers have a kill switch on the lights
> > when the enclosure is opened. You can seriously damage your sight
> > with these lamps, since they are made to be germicidal.
> >
> > Please read up on them if you haven't, and observe all the safety
> > precautions.
> >
> > Harvey
> >
> >
> >
>
> ...<SNIP>...
>
> > >[Non-text portions of this message have been removed]
> >
>
>

[Non-text portions of this message have been removed]

Dne 07. 07. 2013 16:54, piše Mitch Davis:

>
> On Mon, Jul 8, 2013 at 4:19 AM, brane2 <brankob@...
> <mailto:brankob%40s5tehnika.net>> wrote:
> > Dne 07. 07. 2013 15:37, pis(e epa_iii:
> >>
> >> consider the idea that this device may not always be in your
> possession or control.
> >
> > Chill out a little FFS...
>
> Some people live in very litigious societies. However well meaning
> you are, some asshole will always be looking for a reason to sue you,
> and scumbag lawyers are altogether too happy to oblige. Safety
> mechanisms are a way to be seen to take the safety issue seriously,
> which can be a legal defence.
>

Fair enough, but in such environments I wouldn't act on your advice
alone, I would check legal requirements first. One can not deal with
such things on advice of random legal layman.

We are talking here about a couple of technically quite literate guys
here, not some random user.

And UV us bit THAT dangerous. UVC might be sneaky, but let's not
overreact. I'm not opening a tanning boot and a few photons of UVC that
might hit me on rare occasion probably won't kill me.
It might very well be proven that small exposure might be benefitial for
re/seting internal clocks or somesuch....

WRT to your example, it is bizarre. If you are gonna use freak
stupidities and accidents as an argument for so radical safety margins,
then you'd have to live with insane prices of even most rudimentary
things like wall sockets etc etc.

You can't really make a parallel between highly active source of very
ionising radiation and simple UV lamp, this is big exaggerration.

> Also, such a box may end up in the hands of minors, or people who just
> don't realise the danger. Here's an example of how 4 people
> (including a 6 year-old child) died, as a result of not knowing of the
> dangers of the pretty glowing blue stuff they'd found:
>
> http://en.wikipedia.org/wiki/Goi%C3%A2nia_accident
>
> Would be a shame if some young boy or girl lost their eyesight just
> for want of a safety switch...
>
> Mitch.
>
>

[Non-text portions of this message have been removed]

Dne 07. 07. 2013 18:53, piše brane2:

>
> Fair enough, but in such environments I wouldn't act on your advice
> alone, I would check legal requirements first. One can not deal with
> such things on advice of random legal layman.
>

I didn't mean to be rude here, just to say that satisfying legal
constraints usually needs knowing _exact_ requirements and just
plopping _somewhere_ _some_ text is not enough...




[Non-text portions of this message have been removed]

On Sun, Jul 7, 2013 at 8:37 AM, epa_iii <palciatore@...> wrote:

>
> Oh, and do be sure that the emulsion or printed (ink/toner) side of your
> negative/positive is the one in contact with the board.
>

This is the single-most important piece of advice related to contact
printing anything photographic. We used to specify that pcb negatives be
"R/R/E/D"--"right-reading emulsion down." That is, when the negative is
flipped so that is reads as the pcb should read, the "emulsion"--or the
printed deposit of ink, toner, etc.--should be down facing the pcb and not
up facing you. The reason is that light--collimated or not--will diffuse
through the thickness of the film resulting in a blurred print.

I'm with the spirit of Paul's reply that simple equipment is all that's
needed here for a nearly-perfect result. Though I understand (and suffer
from) the malady myself, this is a case in which there should be less
perfectionist hand-wringing and more hands-on doing.
http://www.setsailcoaching.com/maximizing-vs-satisficing-how-happy-are-you-with-your-decisions


73,

Todd
------------------------------------------------------------------------------------
K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
------------------------------------------------------------------------------------
QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design


[Non-text portions of this message have been removed]

I totally agree. Whilst you don't want to completely waste time and effort repeating others' mistakes, there's a lot to be learned from giving version 1.0 a go and seeing if simple will do.

FWIW, for my first board I just got results that are easily good enough for TSSOP by putting the board on the roof of my van about 20cm below a standard fluorescent (i.e. visible light) in my garage.

Fred

> I'm with the spirit of Paul's reply that simple equipment is all that's
> needed here for a nearly-perfect result. Though I understand (and suffer
> from) the malady myself, this is a case in which there should be less
> perfectionist hand-wringing and more hands-on doing.

On Sun, Jul 7, 2013 at 1:06 PM, fred27murphy <fred27murphy@...> wrote:

>
> FWIW, for my first board I just got results that are easily good enough
> for TSSOP by putting the board on the roof of my van about 20cm below a
> standard fluorescent (i.e. visible light) in my garage.
>

A drive-in printer!! Very cool!

Back in the 70s, I used to expose offset printing plates using a 300w blue
frosted bulb with a high-UV output. It was just a regular screw-in
(Edison-base) bulb and I used a common clamp-on lamp at about 30." I used a
sheet of 1" sponge foam and a 1/4" thick glass plate to clamp the negative
and plate during exposure. A very crude but also very effective setup. I
just did a Google search for those bulbs and I haven't found them yet. I'll
keep looking.

73,

Todd
------------------------------------------------------------------------------------
K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
------------------------------------------------------------------------------------
QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design


[Non-text portions of this message have been removed]

Wow.

Interesting story, though it doesn't seem very relevant.

I guess that's the sort of thing we can look forward to
as a result of emphasizing self-esteem over achievement
in our public schools. If we manage to dumb down
everyone to the lowest common denominator then no one
will ever do anything dangerous because they won't know
how. And we wouldn't need groups like this one.

Here's something that will make your hair stand on end:
My exposure box design is the eventual result of a YouTube
video I saw where a guy used Hg vapor lamps with the
glass envelop broken off because apparently *any* such
bulb will produce the necessary radiation if the borosilicate
envelope is removed. I was trying to make the thing as cheap
as possible, so I tried it. Turned out the exposure time was
longer than I wanted and then I found an Hg bulb made for
"safe" UV and so used that. $10 for the bulb and $40 for
the ballast, some MDF and cheap drawer slides and voila!
A spiffy exposure box with reasonably fast exposure times.
Does it leak? Sure, some, but not much. I squint when I
slide the drawer out. The problem with Hg lamps is that
they require a minute to "warm up" and you can't turn them
on again right away if you turn them off, so interlock switches
are not practical. I thought about some elaborate mechanical
interlocks, but decided not to make "perfect" the enemy of
"good enough." The advantage of the Hg lamp is it is nearly
a point UV source. I haven't been able to do 8/8 yet but I
have done 12mil traces with spaces probably less than 8.
My biggest problem now is making high-enough quality masks.
--
Phil M.

----- Original Message -----
From: "Mitch Davis" <mjd@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, July 07, 2013 9:54 AM
Subject: Re: [Homebrew_PCBs] Re: For a DIY exposure box ... is collimated
light an issue?


> On Mon, Jul 8, 2013 at 4:19 AM, brane2 <brankob@...> wrote:
>> Dne 07. 07. 2013 15:37, pis(e epa_iii:
>>>
>>> consider the idea that this device may not always be in your possession
>>> or control.
>>
>> Chill out a little FFS...
>
> Some people live in very litigious societies. However well meaning
> you are, some asshole will always be looking for a reason to sue you,
> and scumbag lawyers are altogether too happy to oblige. Safety
> mechanisms are a way to be seen to take the safety issue seriously,
> which can be a legal defence.
>
> Also, such a box may end up in the hands of minors, or people who just
> don't realise the danger. Here's an example of how 4 people
> (including a 6 year-old child) died, as a result of not knowing of the
> dangers of the pretty glowing blue stuff they'd found:
>
> http://en.wikipedia.org/wiki/Goi%C3%A2nia_accident
>
> Would be a shame if some young boy or girl lost their eyesight just
> for want of a safety switch...
>
> Mitch.
>
>

On Sun, Jul 7, 2013 at 3:27 PM, Phil@Yahoo <yahoo@...> wrote:

> Wow. . . . Interesting story, though it doesn't seem very relevant. . . . I
> guess that's the sort of thing we can look forward to as a result of
> emphasizing self-esteem over achievement in our public schools. If we
> manage to dumb down everyone to the lowest common denominator then no one will
> ever do anything dangerous because they won't know how. And we wouldn't
> need groups like this one.

Wow. Interesting comment, though it doesn't seem very relevant. I guess
it's the sort of thing we can expect when someone tries to bolster his own
self esteem at the expense of others.
By the way, it really wasn't an interesting comment. I was just being
snotty. The comment was in fact the same old blowhard "I'm smart and the
rest of you are fools" spittle. It's similar to "My parents were damn
fools, and I survived, so I get to be a damn fool myself."

73,

Todd
------------------------------------------------------------------------------------
K7TFC / Medford, Oregon, USA / CN82ni / UTC-8


[Non-text portions of this message have been removed]

Phil,

You sound like me. Decades ago I also tested mercury lamps with the outer glass envelope broken off.

Surprisingly it worked worse than with the envelope intact. I eventually figured out that the bare bulb was running too cold and never reached the operating temperature.



Later I found an industrial 400W UV bulb with a matching power supply so I can blast anything with more than needed UV.



The commercial units use a mechanical light shutter so the bulb runs continuously and are up to speed so the exposure times are very fast and consistent.



I also built a 10kW focused carbon-arc lamp with a filtered DC supply. Interestingly, it does not sound like an arc welder, it very quietly slightly hisses.

Bertho



From: Phil@Yahoo Sent: Sunday, July 07, 2013 18:27



Wow.

Interesting story, though it doesn't seem very relevant.

I guess that's the sort of thing we can look forward to
as a result of emphasizing self-esteem over achievement
in our public schools. If we manage to dumb down
everyone to the lowest common denominator then no one
will ever do anything dangerous because they won't know
how. And we wouldn't need groups like this one.

Here's something that will make your hair stand on end:
My exposure box design is the eventual result of a YouTube
video I saw where a guy used Hg vapor lamps with the
glass envelop broken off because apparently *any* such
bulb will produce the necessary radiation if the borosilicate
envelope is removed. I was trying to make the thing as cheap
as possible, so I tried it. Turned out the exposure time was
longer than I wanted and then I found an Hg bulb made for
"safe" UV and so used that. $10 for the bulb and $40 for
the ballast, some MDF and cheap drawer slides and voila!
A spiffy exposure box with reasonably fast exposure times.
Does it leak? Sure, some, but not much. I squint when I
slide the drawer out. The problem with Hg lamps is that
they require a minute to "warm up" and you can't turn them
on again right away if you turn them off, so interlock switches
are not practical. I thought about some elaborate mechanical
interlocks, but decided not to make "perfect" the enemy of
"good enough." The advantage of the Hg lamp is it is nearly
a point UV source. I haven't been able to do 8/8 yet but I
have done 12mil traces with spaces probably less than 8.
My biggest problem now is making high-enough quality masks.
--
Phil M.





[Non-text portions of this message have been removed]

On 07/08/2013 12:27 AM, Phil@Yahoo wrote:

> Wow.
>
> Interesting story, though it doesn't seem very relevant.
>
> I guess that's the sort of thing we can look forward to
> as a result of emphasizing self-esteem over achievement
> in our public schools. If we manage to dumb down
> everyone to the lowest common denominator then no one
> will ever do anything dangerous because they won't know
> how. And we wouldn't need groups like this one.
>
> Here's something that will make your hair stand on end:
> My exposure box design is the eventual result of a YouTube
> video I saw where a guy used Hg vapor lamps with the
> glass envelop broken off because apparently *any* such
> bulb will produce the necessary radiation if the borosilicate
> envelope is removed. I was trying to make the thing as cheap
> as possible, so I tried it. Turned out the exposure time was
> longer than I wanted and then I found an Hg bulb made for
> "safe" UV and so used that. $10 for the bulb and $40 for
> the ballast, some MDF and cheap drawer slides and voila!
> A spiffy exposure box with reasonably fast exposure times.
> Does it leak? Sure, some, but not much. I squint when I
> slide the drawer out. The problem with Hg lamps is that
> they require a minute to "warm up" and you can't turn them
> on again right away if you turn them off, so interlock switches
> are not practical. I thought about some elaborate mechanical
> interlocks, but decided not to make "perfect" the enemy of
> "good enough." The advantage of the Hg lamp is it is nearly
> a point UV source. I haven't been able to do 8/8 yet but I
> have done 12mil traces with spaces probably less than 8.
> My biggest problem now is making high-enough quality masks.
> --
> Phil M.
>

HG vapour lights have the same UVC wavelength as the germicidal lamps,
i.e. 273 nm.

Not to poke your eye with a couple of fingers :-) Hg vapour lamps with
broken outer shell produce a lot of Ozone (O3) which in higher
concentrations can kill you by suffocation.

O3 is happily received by haemoglobin in our red blod cells, but the
rest of our bodily cells have no clue how to use that variety of Oxygen.

Oxygen depravation = suffocation = untimely meeting with ... :-)


--
Best Regards,
Q Systems
Zoran A. Šćepanović
zastos@...
Skype: zoran.a.scepanovic
http://zastos.com
+381 63 609-993

-..-
If a fish is to get away, you must catch it first.

Years back I had a nice exposure box, three 18" desk lamp size T8 15W UV tubes on the bottom half and 3 on the top half. Boxes (upper and lower)were of white painted wood about 20"L x 8"W x 5.5"H. The bottom half had 1/4" glass plate about 4" above the tubes to support the board and artwork. On top of that was another pieced of glass that I could clamp down to compress the art to the board --just four bolts with wing nuts. After clamping down the top glass you set on the the upper box and turned the timer to 3-5 minutes, the timer would ding and the lights would shut off. Worked great. There was no collimation so you had to make sure the emulsion on the artwork was against the board. Don't know how it would have been with a TSOP.

Here is another idea for consideration. On Ebay one can buy HID Xenon auto head light kits for around $30. The kits have 2 bulbs with 2 ballast but no reflector etc. With a little research I discovered these are not really Xenon arc lamps but Metal Halide lamps that include some Xenon. But in any case they should make plenty of UV especially if the UV filter shield is removed. So I am thinking with some sort of parabolic reflector it could make a nice collimated UV exposure source. The posting even shows a 30000K Pink/Violet bulb.

http://www.ebay.com/itm/HID-Kit-Xenon-Headlight-H1-H3-H4-H7-H11-9004-9006-9007-/150948612421?pt=Motors_Car_Truck_Parts_Accessories&hash=item23253d0945&vxp=mtr

Craig

Hmmm....
A tad bitter and hypersensitive, but boring. And off topic.
Try CL R&R
--
Phil M.

----- Original Message -----
From: "Todd F. Carney / K7TFC" <k7tfc@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, July 07, 2013 3:59 PM
Subject: Re: [Homebrew_PCBs] Re: For a DIY exposure box ... is collimated
light an issue?


>
> On Sun, Jul 7, 2013 at 3:27 PM, Phil@Yahoo <yahoo@...> wrote:
>
>> Wow. . . . Interesting story, though it doesn't seem very relevant. . . .
>> I
>> guess that's the sort of thing we can look forward to as a result of
>> emphasizing self-esteem over achievement in our public schools. If we
>> manage to dumb down everyone to the lowest common denominator then no one
>> will
>> ever do anything dangerous because they won't know how. And we wouldn't
>> need groups like this one.
>
>
> Wow. Interesting comment, though it doesn't seem very relevant. I guess
> it's the sort of thing we can expect when someone tries to bolster his own
> self esteem at the expense of others.
> By the way, it really wasn't an interesting comment. I was just being
> snotty. The comment was in fact the same old blowhard "I'm smart and the
> rest of you are fools" spittle. It's similar to "My parents were damn
> fools, and I survived, so I get to be a damn fool myself."
>
> 73,
>
> Todd
> ------------------------------------------------------------------------------------
> K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
>
>

If you choose not to take someone's advice regarding safety, that is your choice.

But being snotty is not necessary.

Steve Greenfield AE7HD
your friendly neighborhood moderator

--- In Homebrew_PCBs@yahoogroups.com, brane2 <brankob@...> wrote:
>
> Of course. I was thinking about twelve inches of lead just for an outer
> part of the shield. Im kind of lingering between Uranium and
> Kurchatovium for inner part.
>
> On a related note, I never jerk off outside of hazmat suit. Better safe
> than sorry.
>
> Chill out a little FFS...
>
>
>

In the '80s, I used bulbs that fit that description to expose negative resist coated boards.

They were called "Gro" lights. There are several brands, that was the one I used. Just a 65W reflector bulb about 18 inches away, clamped under a sheet of glass very close to what you describe below.

I think it took about a minute and a half?

Steve Greenfield AE7HD

--- In Homebrew_PCBs@yahoogroups.com, "Todd F. Carney / K7TFC" <k7tfc@...> wrote:

> Back in the 70s, I used to expose offset printing plates using a 300w blue
> frosted bulb with a high-UV output. It was just a regular screw-in
> (Edison-base) bulb and I used a common clamp-on lamp at about 30." I used a
> sheet of 1" sponge foam and a 1/4" thick glass plate to clamp the negative
> and plate during exposure. A very crude but also very effective setup. I
> just did a Google search for those bulbs and I haven't found them yet. I'll
> keep looking.
>
> 73,
>
> Todd
> ------------------------------------------------------------------------------------
> K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
> ------------------------------------------------------------------------------------
> QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design
>

On Mon, Jul 8, 2013 at 9:14 PM, AlienRelics <alienrelics@...> wrote:

> In the '80s, I used bulbs that fit that description to expose negative
> resist coated boards. . . . They were called "Gro" lights. There are
> several brands, that was the one I used. Just a 65W reflector bulb about 18
> inches away, clamped under a sheet of glass very close to what you describe
> below.

Steve,

The bulbs I used were sold through graphic-arts suppliers. I haven't been
able to find them by Googling yet. Maybe they're not made anymore. I'm
pretty sure the Gro brand of grow lights is still around, though. I think
I've even seen them at Walmart. Fish and aquarium stores have full-spectrum
bulbs, too.

73,

Todd
------------------------------------------------------------------------------------
K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
------------------------------------------------------------------------------------
QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design


[Non-text portions of this message have been removed]

On Mon, Jul 8, 2013 at 10:34 PM, Todd F. Carney / K7TFC <k7tfc@...>
wrote:

> On Mon, Jul 8, 2013 at 9:14 PM, AlienRelics <alienrelics@...> wrote:
>
>
>> In the '80s, I used bulbs that fit that description to expose negative
>> resist coated boards. . . . They were called "Gro" lights. There are
>> several brands, that was the one I used. Just a 65W reflector bulb about 18
>> inches away, clamped under a sheet of glass very close to what you describe
>> below.
>
>
> Steve,
> The bulbs I used were sold through graphic-arts suppliers. I haven't been
> able to find them by Googling yet. Maybe they're not made anymore. I'm
> pretty sure the Gro brand of grow lights is still around, though. I think
> I've even seen them at Walmart. Fish and aquarium stores have full-spectrum
> bulbs, too.
>
>

Damn me if I didn't finally figure out where to look! Google: "daylight
photoflood." Lots of high-wattage/lumens/color temperature bulbs to be
found made by several manufacturers. These are the ones I used in the *
Vorzeit--*in "the before time." If you have a decent camera or photo supply
store nearby (they're getting rare!), you might find them there.

Here's B&H in NYC, for instance:
http://www.bhphotovideo.com/c/product/808082-REG/Ushio_1000046_BCA_Incandescent_Photoflood_Lamp.html

Freestyle Photo: http://www.freestylephoto.biz/search?q=photoflood

Adorama:
http://www.adorama.com/searchsite/default.aspx?searchinfo=photoflood

If you're into photography, these outfits are probably familiar to you from
their big multi-page ads in the photo magazines.

One thing to keep in mind about these daylight photofloods is that you
might already have every other piece of equipment you need: a reflector
clamp-on lamp being the most elaborate.

73,

Todd
------------------------------------------------------------------------------------
K7TFC / Medford, Oregon, USA / CN82ni / UTC-8


[Non-text portions of this message have been removed]

That would be Carbon Monoxide (which binds to hemoglobin better than normal Oxygen, causing suffocation). Ozone is a pulmonary irritant, causing lung damage in sufficient concentration.

From an MSDS (Health Effects) "May cause irritation of the respiratory tract experienced as nasal discomfort, dryness, irritation of the throat, pain or congestion of the chest, difficult breathing or coughing. Irritation of the eyes, headache, nausea and drowsiness may also occur. Concentrations above 9 ppm have been found to result in pneumonia. Exposure to high concentrations could be fatal."

<http://www.cdc.gov/niosh/idlh/10028156.html> stated "The chosen IDLH is based on the statement by AIHA [1966] that pulmonary edema developed in welders who had a severe acute exposure to an estimated 9 ppm ozone plus other air pollutants [Kleinfeld et al. 1957]."

Donald.
--
*Plain Text* email -- it's an accessibility issue
() no proprietary attachments; no html mail
/\ ascii ribbon campaign - <www.asciiribbon.org>

----- Original Message -----
> From: "\"Zoran A. Šćepanović\"" <zastos@...>
> To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
> Sent: Monday, July 8, 2013 2:26:47 AM
> Subject: Re: [Homebrew_PCBs] Re: For a DIY exposure box ... is collimated light an issue?
> On 07/08/2013 12:27 AM, Phil@Yahoo wrote:
> > Wow.
> >
> > Interesting story, though it doesn't seem very relevant.
> >
> > I guess that's the sort of thing we can look forward to
> > as a result of emphasizing self-esteem over achievement
> > in our public schools. If we manage to dumb down
> > everyone to the lowest common denominator then no one
> > will ever do anything dangerous because they won't know
> > how. And we wouldn't need groups like this one.
> >
> > Here's something that will make your hair stand on end:
> > My exposure box design is the eventual result of a YouTube
> > video I saw where a guy used Hg vapor lamps with the
> > glass envelop broken off because apparently *any* such
> > bulb will produce the necessary radiation if the borosilicate
> > envelope is removed. I was trying to make the thing as cheap
> > as possible, so I tried it. Turned out the exposure time was
> > longer than I wanted and then I found an Hg bulb made for
> > "safe" UV and so used that. $10 for the bulb and $40 for
> > the ballast, some MDF and cheap drawer slides and voila!
> > A spiffy exposure box with reasonably fast exposure times.
> > Does it leak? Sure, some, but not much. I squint when I
> > slide the drawer out. The problem with Hg lamps is that
> > they require a minute to "warm up" and you can't turn them
> > on again right away if you turn them off, so interlock switches
> > are not practical. I thought about some elaborate mechanical
> > interlocks, but decided not to make "perfect" the enemy of
> > "good enough." The advantage of the Hg lamp is it is nearly
> > a point UV source. I haven't been able to do 8/8 yet but I
> > have done 12mil traces with spaces probably less than 8.
> > My biggest problem now is making high-enough quality masks.
> > --
> > Phil M.
> >
>
> HG vapour lights have the same UVC wavelength as the germicidal lamps,
> i.e. 273 nm.
>
> Not to poke your eye with a couple of fingers :-) Hg vapour lamps with
> broken outer shell produce a lot of Ozone (O3) which in higher
> concentrations can kill you by suffocation.
>
> O3 is happily received by haemoglobin in our red blod cells, but the
> rest of our bodily cells have no clue how to use that variety of
> Oxygen.
>
> Oxygen depravation = suffocation = untimely meeting with ... :-)
>
>
> --
> Best Regards,
> Q Systems
> Zoran A. Šćepanović
> zastos@...
> Skype: zoran.a.scepanovic
> http://zastos.com
> +381 63 609-993
>
> -..-
> If a fish is to get away, you must catch it first.
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Darn.

I was planning on getting an appliance box and closing it up with myself
inside with a mercury vapor lamp with the glass envelope broken off and
making dozens of circuit boards while staring at that amazing light before
letting the regular light in.

Guess I'll have to come up with another plan.
--

----- Original Message -----
From: "Donald H Locker" <dhlocker@...>
To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, July 14, 2013 3:46 PM
Subject: Re: [Homebrew_PCBs] Re: For a DIY exposure box ... is collimated
light an issue?


That would be Carbon Monoxide (which binds to hemoglobin better than normal
Oxygen, causing suffocation). Ozone is a pulmonary irritant, causing lung
damage in sufficient concentration.

From an MSDS (Health Effects) "May cause irritation of the respiratory tract
experienced as nasal discomfort, dryness, irritation of the throat, pain or
congestion of the chest, difficult breathing or coughing. Irritation of the
eyes, headache, nausea and drowsiness may also occur. Concentrations above 9
ppm have been found to result in pneumonia. Exposure to high concentrations
could be fatal."

<http://www.cdc.gov/niosh/idlh/10028156.html> stated "The chosen IDLH is
based on the statement by AIHA [1966] that pulmonary edema developed in
welders who had a severe acute exposure to an estimated 9 ppm ozone plus
other air pollutants [Kleinfeld et al. 1957]."

Donald.
--
*Plain Text* email -- it's an accessibility issue
() no proprietary attachments; no html mail
/\ ascii ribbon campaign - <www.asciiribbon.org>

----- Original Message -----
> From: "\"Zoran A. Šćepanović\"" <zastos@...>
> To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
> Sent: Monday, July 8, 2013 2:26:47 AM
> Subject: Re: [Homebrew_PCBs] Re: For a DIY exposure box ... is collimated
> light an issue?
> On 07/08/2013 12:27 AM, Phil@Yahoo wrote:
> > Wow.
> >
> > Interesting story, though it doesn't seem very relevant.
> >
> > I guess that's the sort of thing we can look forward to
> > as a result of emphasizing self-esteem over achievement
> > in our public schools. If we manage to dumb down
> > everyone to the lowest common denominator then no one
> > will ever do anything dangerous because they won't know
> > how. And we wouldn't need groups like this one.
> >
> > Here's something that will make your hair stand on end:
> > My exposure box design is the eventual result of a YouTube
> > video I saw where a guy used Hg vapor lamps with the
> > glass envelop broken off because apparently *any* such
> > bulb will produce the necessary radiation if the borosilicate
> > envelope is removed. I was trying to make the thing as cheap
> > as possible, so I tried it. Turned out the exposure time was
> > longer than I wanted and then I found an Hg bulb made for
> > "safe" UV and so used that. $10 for the bulb and $40 for
> > the ballast, some MDF and cheap drawer slides and voila!
> > A spiffy exposure box with reasonably fast exposure times.
> > Does it leak? Sure, some, but not much. I squint when I
> > slide the drawer out. The problem with Hg lamps is that
> > they require a minute to "warm up" and you can't turn them
> > on again right away if you turn them off, so interlock switches
> > are not practical. I thought about some elaborate mechanical
> > interlocks, but decided not to make "perfect" the enemy of
> > "good enough." The advantage of the Hg lamp is it is nearly
> > a point UV source. I haven't been able to do 8/8 yet but I
> > have done 12mil traces with spaces probably less than 8.
> > My biggest problem now is making high-enough quality masks.
> > --
> > Phil M.
> >
>
> HG vapour lights have the same UVC wavelength as the germicidal lamps,
> i.e. 273 nm.
>
> Not to poke your eye with a couple of fingers :-) Hg vapour lamps with
> broken outer shell produce a lot of Ozone (O3) which in higher
> concentrations can kill you by suffocation.
>
> O3 is happily received by haemoglobin in our red blod cells, but the
> rest of our bodily cells have no clue how to use that variety of
> Oxygen.
>
> Oxygen depravation = suffocation = untimely meeting with ... :-)
>
>
> --
> Best Regards,
> Q Systems
> Zoran A. Šćepanović
> zastos@...
> Skype: zoran.a.scepanovic
> http://zastos.com
> +381 63 609-993
>
> -..-
> If a fish is to get away, you must catch it first.
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>


------------------------------------

Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links

On Mon, Jul 15, 2013 at 3:34 PM, Phil@Yahoo <yahoo@...> wrote:

>
> I was planning on getting an appliance box and closing it up with myself
> inside with a mercury vapor lamp with the glass envelope broken off and
> making dozens of circuit boards while staring at that amazing light before
> letting the regular light in.
>
> Guess I'll have to come up with another plan.

LOL, paid.