Homebrew_PCBs

----- Original Message -----

----- Original Message -----
From: "John Craddock" <John.Craddock@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, September 25, 2006 3:35 AM
Subject: RE: [Homebrew_PCBs] UV Light Sources


>I read somewhere on the web that a mercury vapour lamp with the outer uv
>blocking envelope removed gives a very good source of uv light for
>photo-pcb resist curing. Obviously removing the outer envelope would
>require that the uv exposure box be totally enclosed when the system is
>operating. Can any one confirm that this is comparable or better than the
>black-light fluorescent approach?

It's a lot better (much shorter expoosure), but needs to be a long way from
the PCB/artwork for good collimation (something like 1 m, IIRC). I've got
some similar sodium lamps that can have the outer envelope removed. The
ballasts can be difficult to find. For accurate exposure I think you need
some sort of shutter arrangement as they take some time to warm up.

Leon

>> John Craddock wrote:
>>
>> I read somewhere on the web that a
>> mercury vapour lamp with the outer uv
>> blocking envelope removed gives a very
>> good source of uv light for photo-pcb
>> resist curing. Obviously removing the
>> outer envelope would require that the
>> uv exposure box be totally enclosed when
>> the system is operating. Can any one
>> confirm that this is comparable or
>> better than the black-light fluorescent
>> approach?

> WilliamK wrote:
> Well mercury vapor bulbs are a popular
> choice for lighting amongst reptile owners
> because they offer a decent amount of UVB
> that is needed by a number of reptile
> species for proper vitamin D3 production
> but I don't know that it would be enough
> for curing the photo resist. For that you
> might want to look at the UV bulbs used in
> aquarium and pond UV sterilizers. They put
> out considerably more UV to the point that
> they can be hazardous if not totally
> enclosed.

> -----Original Message-----
> From: Leon Heller [mailto:leon.heller@...]
> Sent: 25 September 2006 16:27
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] UV Light Sources
> >operating. Can any one confirm that this is comparable or
> better than the
> >black-light fluorescent approach?
>
> It's a lot better (much shorter expoosure), but needs to be a
> long way from
> the PCB/artwork for good collimation (something like 1 m,
> IIRC). I've got
> some similar sodium lamps that can have the outer envelope
> removed. The
> ballasts can be difficult to find. For accurate exposure I
> think you need
> some sort of shutter arrangement as they take some time to warm up.
>
> Leon

----- Original Message -----
From: "John Craddock" <John.Craddock@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, September 25, 2006 8:13 AM
Subject: RE: [Homebrew_PCBs] UV Light Sources


>
>
>> -----Original Message-----
>> From: Leon Heller [mailto:leon.heller@...]
>> Sent: 25 September 2006 16:27
>> To: Homebrew_PCBs@yahoogroups.com
>> Subject: Re: [Homebrew_PCBs] UV Light Sources
>> >operating. Can any one confirm that this is comparable or
>> better than the
>> >black-light fluorescent approach?
>>
>> It's a lot better (much shorter expoosure), but needs to be a
>> long way from
>> the PCB/artwork for good collimation (something like 1 m,
>> IIRC). I've got
>> some similar sodium lamps that can have the outer envelope
>> removed. The
>> ballasts can be difficult to find. For accurate exposure I
>> think you need
>> some sort of shutter arrangement as they take some time to warm up.
>>
>> Leon
> Thanks Leon
> For the collimation I was going to use a parabolic reflector. With a 16"
> (400mm) dia., reflector it would seem to be feasible to have a working
> exposure area of 12" to 18" (300 to 400mm) Instead of a shutter I was
> thinking of using a slide-in frame holder. In OZ we can get 250 watt self
> ballasting globes the run off our 240 volt mains supply. This set-up would
> be far less expensive than say 4 or 5 fluro tubes plus their associated
> ballasts, starters etc (at least in the antipodes).

I was going to remove the envelope from one of my sodium lamps, but the cat
knocked it off the bench onto the floor and did it for me. 8-) I got some
ceramic bulb holders without any problems, I really must get a ballast and
try it out. I got the bulbs cheap on Ebay; I should have got one of the
units you mention, it would have been less trouble.

Leon

>Most expensive comercial
>machines use them I think.

>
>
>
> > -----Original Message-----
> > From: Leon Heller [mailto:leon.heller@...]
> > Sent: 25 September 2006 16:27
> > To: Homebrew_PCBs@yahoogroups.com
> > Subject: Re: [Homebrew_PCBs] UV Light Sources
> > >operating. Can any one confirm that this is comparable or
> > better than the
> > >black-light fluorescent approach?
> >
> > It's a lot better (much shorter expoosure), but needs to be a
> > long way from
> > the PCB/artwork for good collimation (something like 1 m,
> > IIRC). I've got
> > some similar sodium lamps that can have the outer envelope
> > removed. The
> > ballasts can be difficult to find. For accurate exposure I
> > think you need
> > some sort of shutter arrangement as they take some time to warm up.
> >
> > Leon
> Thanks Leon
> For the collimation I was going to use a parabolic reflector. With a

> Regards
> John C
>

>There is no need to worry about collimation of the beam unless you
>are exposing very large panels.

> -----Original Message-----
> From: derekhawkins [mailto:eldata@...]
> Sent: 26 September 2006 00:18
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: UV Light Sources

> Craddock must have at least searched
> these archives for >mercury vapor< before starting this thread. Flags
> raise when "people play the fool to catch the wise", begging the
> question "What's his MO?".
>
> --- In Homebrew_PCBs@yahoogroups.com, "Andrew"
> <andrewm1973@...> wrote:

> -----Original Message-----
> From: twb8899 [mailto:twb8899@...]
> Sent: 26 September 2006 04:17
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: UV Light Sources
>
> It's just a standard 1000 watt mecury vapor bulb with a reflector. There is
> no need to worry about collimation of the beam unless you are exposing
> very large panels. Don't break the outer glass from the lamp unless
> you want ozone.

>
> Just the other day I saw a lamp assembly that would be perfect for a
> homebrew exposure unit. It was a mercury vapor lamp with reflector in
> a metal enclosure at the base of a flagpole. This lamp looked like a
> 400 watt bulb but that would work great for dry film resist. Just
> build a box around the lamp assembly and leave a slot at the bottom
> for your contact frame to slide in and out. The bulb could be about 12
> inches from the contact frame.
>

> At 400 watts I'm guessing about 45 seconds for exposure at 12 inches.
> My system uses the 1000 watt lamps. They idle at 1000 watts and during
> exposure they are overdriven to 1500 watts. Exposure time for DuPont
> 1.5 mil photoresist is 17 seconds. I do 5 mil lines and spaces daily
> with this system. My film work is photoplotted on 7 mil thick films.
> Dry film resist is negative acting and has a fast exposure time.
> Positive resists are slower and will take longer to expose.
>

> Tom

>FYI in the English language we spell "vapor" as vapour, so a search
>missed it

>>DO NOT break the outer glass shell of a mercury vapour lamp! It
>>will radiate a lot of short wave UV (UV-A) which is dangerous for
>>eyes and skin, and it generates lot of ozone (O3). Good results
>>could be obtained without breaking the outer glass shell.

>Your insinuation in the snide comment above is pretty dammed
>offensive and totally uncalled for in a list such as this.

>>There is no need to worry about collimation of the beam unless you
>>are exposing very large panels.
>
> Hear, hear!

> -----Original Message-----
> From: derekhawkins [mailto:eldata@...]
> Sent: 26 September 2006 10:05
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: UV Light Sources
>
>
> >FYI in the English language we spell "vapor" as vapour, so a search
> >missed it
>
> Missed what? Searching on >mercury vapour< gives another set of hits
> including this;
>
> >>DO NOT break the outer glass shell of a mercury vapour lamp! It
> >>will radiate a lot of short wave UV (UV-A) which is dangerous for
> >>eyes and skin, and it generates lot of ozone (O3). Good results
> >>could be obtained without breaking the outer glass shell.

> I'm inquisitive too...What are you really up to? You're coming
> across like a "Man dressed in black".
>

> Tom, thank you very much for that information. I have a few

>
> > -----Original Message-----
> > From: twb8899 [mailto:twb8899@...]
> > Sent: 26 September 2006 04:17
> > To: Homebrew_PCBs@yahoogroups.com
> > Subject: [Homebrew_PCBs] Re: UV Light Sources
> >
> > It's just a standard 1000 watt mecury vapor bulb with a reflector.

> > no need to worry about collimation of the beam unless you are exposing
> > very large panels. Don't break the outer glass from the lamp unless
> > you want ozone.

> Is the reflector built into the globe i.e.. is it a PAR type globe

> >
> > Just the other day I saw a lamp assembly that would be perfect for a
> > homebrew exposure unit. It was a mercury vapor lamp with reflector in
> > a metal enclosure at the base of a flagpole. This lamp looked like a
> > 400 watt bulb but that would work great for dry film resist. Just
> > build a box around the lamp assembly and leave a slot at the bottom
> > for your contact frame to slide in and out. The bulb could be about 12
> > inches from the contact frame.
> >


> I was going to use a 250 watt self-ballasting globe. Do you think

>
> > At 400 watts I'm guessing about 45 seconds for exposure at 12 inches.
> > My system uses the 1000 watt lamps. They idle at 1000 watts and during
> > exposure they are overdriven to 1500 watts. Exposure time for DuPont
> > 1.5 mil photoresist is 17 seconds. I do 5 mil lines and spaces daily
> > with this system. My film work is photoplotted on 7 mil thick films.
> > Dry film resist is negative acting and has a fast exposure time.
> > Positive resists are slower and will take longer to expose.
> >
> Would you use a similar distance of 12 inches for a 250 watt unit?
> Would 2 * 250 watt globes be a better way to go? I will be exposing

> Once again Tom thank you for your guidance.
> Regards
> John C
>

> -----Original Message-----
> From: Russell Shaw [mailto:rjshaw@...]
> Sent: 26 September 2006 12:17
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Re: UV Light Sources

> I made a UV lightbox with a 125Watt HID lamp (HPR-125) 24"
> from the glass,
> and in a cylindrical parabolic reflector (lamp lays
> horizontal). 90%+ exposure
> happens in 30secs, and i found a good optimum to use is 90secs for
> pre-coated negative pcb. The pcb is held against the glass by the lid
> that has a layer of sponge.
>
> Without the reflector and beam collimation, you'll need a bigger globe
> for the same exposure time.
>

----- Original Message -----
From: "John Craddock" <John.Craddock@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, September 26, 2006 4:07 AM
Subject: RE: [Homebrew_PCBs] Re: UV Light Sources


>
>
>> -----Original Message-----
>> From: derekhawkins [mailto:eldata@...]
>> Sent: 26 September 2006 10:05
>> To: Homebrew_PCBs@yahoogroups.com
>> Subject: [Homebrew_PCBs] Re: UV Light Sources
>>
>>
>> >FYI in the English language we spell "vapor" as vapour, so a search
>> >missed it
>>
>> Missed what? Searching on >mercury vapour< gives another set of hits
>> including this;
>>
>> >>DO NOT break the outer glass shell of a mercury vapour lamp! It
>> >>will radiate a lot of short wave UV (UV-A) which is dangerous for
>> >>eyes and skin, and it generates lot of ozone (O3). Good results
>> >>could be obtained without breaking the outer glass shell.
> That was precisely the reason for my question (see the first post on this
> thread). I understand from my web searching that UV-A is the radiation
> band that actively polymerises the UV resist. I further understand that
> the more intense the UV-A radiation is the quicker the polymerisation. I
> have also read that the quicker the exposure, the better is the definition
> achievable. Seeing as the exposure unit would be fully enclosed, I don't
> see a problem with the eyes and skin bit. Anyway, from the research that I
> have done, it seems that the dangerous radiation bands are UV-B and UV-C;
> so your quotation is quite incorrect on that point but the UV-B and UV-C
> also is unblocked by breaking the glass filter. So the recommendation in
> that excerpt is appropriate for some purposes. However it is out of
> context so I cannot tell. The so-called solariums (facial tanners) rely on
> UV-A as their active radiation ingredient so it cannot be too harmful.
> Ozone has got me a bit worried though.

Several people remove the outer envelope, it has to be done with sodium
vapour lamps anyway. I think that the Hg lamps will emit a lot of UV as it
is. I used to get a lot of ozone from EPROM eraser tubes (germicidal tubes),
so I'm used to it. It gets converted to O2 quite quickly, and the main
effect is as an irritant. We will only have it on for a few minutes at a
time, so I can't see it being a problem.

They used to pump O3 throught the London Underground system at night, to
kill germs. Perhaps they still do. I think a carbon filter will remove O3,
they are used on photocopiers, which used to emit lots of ozone. At any
rate, the old Xerox ones did - I used to work for Rank-Xerox (UK). It was
produced by the corotron which charged the photoreceptor.

Leon
--
Leon Heller, G1HSM
Suzuki SV1000S motorcycle
leon.heller@...
http://www.geocities.com/leon_heller

>
>
>
> > -----Original Message-----
> > From: derekhawkins [mailto:eldata@...]
> > Sent: 26 September 2006 00:18
> > To: Homebrew_PCBs@yahoogroups.com
> > Subject: [Homebrew_PCBs] Re: UV Light Sources
> Snip
> > Craddock must have at least searched
> > these archives for >mercury vapor< before starting this thread. Flags
> > raise when "people play the fool to catch the wise", begging the
> > question "What's his MO?".
> >
> > --- In Homebrew_PCBs@yahoogroups.com, "Andrew"
> > <andrewm1973@> wrote:
> Derek
> FYI in the English language we spell "vapor" as vapour, so a search

> Regards
> John C

>

>Without the reflector and beam collimation, you'll need a bigger
>globe for the same exposure time.

>>> >>DO NOT break the outer glass shell of a mercury vapour lamp! It
>>> >>will radiate a lot of short wave UV (UV-A) which is dangerous for

>>> >>eyes and skin, and it generates lot of ozone (O3). Good results
>>> >>could be obtained without breaking the outer glass shell.

>> That was precisely the reason for my question (see the first post on this
>> thread). I understand from my web searching that UV-A is the radiation

>> band that actively polymerises the UV resist. I further understand that

>> have done, it seems that the dangerous radiation bands are UV-B and UV-C;
>> so your quotation is quite incorrect on that point but the UV-B and UV-C
>> also is unblocked by breaking the glass filter. So the recommendation in

>> that excerpt is appropriate for some purposes. However it is out of
>> context so I cannot tell. The so-called solariums (facial tanners) rely on
>> UV-A as their active radiation ingredient so it cannot be too harmful.
>> Ozone has got me a bit worried though.

> Several people remove the outer envelope, it has to be done with sodium
> vapour lamps anyway. I think that the Hg lamps will emit a lot of UV as it
> is. I used to get a lot of ozone from EPROM eraser tubes (germicidal tubes),

> so I'm used to it. It gets converted to O2 quite quickly, and the main
> effect is as an irritant. We will only have it on for a few minutes at a
> time, so I can't see it being a problem.

> They used to pump O3 throught the London Underground system at night, to
> kill germs. Perhaps they still do. I think a carbon filter will remove O3,
> they are used on photocopiers, which used to emit lots of ozone. At any
> rate, the old Xerox ones did - I used to work for Rank-Xerox (UK). It was
> produced by the corotron which charged the photoreceptor.

> Leon
> --
> Leon Heller, G1HSM
> Suzuki SV1000S motorcycle
> leon.heller@...
> http://www.geocities.com/leon_heller

>>Without the reflector and beam collimation, you'll need a bigger
>>globe for the same exposure time.
>
> This is more to do with focus than collimation. Parallel rays would be
> better than divergent rays but convergent rays would even be better
> than parallel rays if shortest exposure time was the only goal.

>That's just a roundabout way of saying you get the fastest exposure
>by focusing all the light to a smaller area, maximizing the power
>density.

> -----Original Message-----
> From: Steve [mailto:alienrelics@...]
> Sent: 27 September 2006 00:13
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: UV Light Sources

>
> Please watch your language and your temper.
>
> FYI, that's American English.... ;')
>
> Derek, I must have missed something, I wasn't picking up any ulterior
> (ulteriour?) motives.
>
> Steve Greenfield

----- Original Message -----

>Russell Shaw wrote:
>> derekhawkins wrote:
>>
>>>>Russell Shaw wrote:
>>>>Without the reflector and beam collimation, you'll need a bigger
>>>>globe for the same exposure time.
>>>
>>>This is more to do with focus than collimation. Parallel rays would be
>>>better than divergent rays but convergent rays would even be better
>>>than parallel rays if shortest exposure time was the only goal.
>>
>> That's just a roundabout way of saying you get the fastest exposure by
>> focusing all the light to a smaller area, maximizing the power density.

> If you remove the reflector and put a collimator in front of the lamp
> you'll get your collimation without focus. Yes, nice low intensity
> parallel rays.

>Derek, you are on moderated status.

> Huh? I was taking Derek to task. How have I offended you?

> Steve Greenfield