Homebrew PCBs

Hi all. I have read a few things now about LED UV exposure units. I really like the idea and want to make one. I want to spread the light out nicely though from the LEDs. I have tried searching for materials that might do this. I see maybe some opaque acrylic might work but sure there are actually some materials out there designed for the job. Anyone found any good material for this or have any suggestions? 

I was wondering if maybe just roughing up a piece of acrylic might do the job. I might try that but really need to get some first. 

Thanks

Trev

Here's mine: http://www.delorie.com/pcb/uvled/

I went for the "grid of LEDs" solution - I did NOT want to spread out
the UV as they were already pretty well focused and I wanted to avoid
blurred edges on my exposures.

Maybe one of these days I'll build one that uses a circuit board so I
can line up the LEDs more accurately.

Hi DJ Delorie. 

You really are the main, you have done everything. lol

So have you used the UV box much? Does it give good results?

Looking at the picture, it seems yours does not spread out too even or is that just the ways it apears?

Trev

It says thay you hoped yours were more spread out. 
--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:

>
> 
> Here's mine: http://www.delorie.com/pcb/uvled/
> 
> I went for the "grid of LEDs" solution - I did NOT want to spread out
> the UV as they were already pretty well focused and I wanted to avoid
> blurred edges on my exposures.
> 
> Maybe one of these days I'll build one that uses a circuit board so I
> can line up the LEDs more accurately.
>

"trevwhite74" <trevor.white100@...> writes:
> You really are the main, you have done everything. lol

No, there are others here who have done all I have done and more.

> So have you used the UV box much? Does it give good results?

I've used it quite a bit.  It seems to work well *if* you have a
vacuum system.  Here are some 5 mil and 3 mil lines exposed with it:

        http://www.delorie.com/pcb/djspirals/

> Looking at the picture, it seems yours does not spread out too even
> or is that just the ways it apears?

You are seeing only the visible portion of the spectrum; they radiate
mostly in the UV.  The spacing was designed to take into account their
UV pattern.  Plus, I don't recall if that picture was taken before or
after I went through and aligned all the individual LEDs.

> I've used it quite a bit.  It seems to work well *if* you have a
> vacuum system.  Here are some 5 mil and 3 mil lines exposed with it:
> 
Why do you need a vacuum system? Is this to make sure the mask layer is tightly against the board?

>         http://www.delorie.com/pcb/djspirals/

Those are really very good. I remember using your spirals to check out my 1200dpi laser. I have not had chance to actually generate any etched results. Your 3 mil is very impressive. 

> 
> You are seeing only the visible portion of the spectrum; they radiate
> mostly in the UV.  The spacing was designed to take into account their
> UV pattern.  Plus, I don't recall if that picture was taken before or
> after I went through and aligned all the individual LEDs.
>

I thought the visual light would show something similar to what would be happening with the UV. I have found some superflux UV LEDs that have a viewing angle of 100+ degrees so I was thinking I could make a thinner version and also make two so I could do both sides at once. I did a bit of math and reckon I probably only require the board to be 2cm - 3cm away from the LEDs. I just do not at this moment know how good the intensity will be. I suppose I just have to give it a shot really. 

Trev

"trevwhite74" <trevor.white100@...> writes:
> Why do you need a vacuum system? Is this to make sure the mask layer
> is tightly against the board?

Yes, it just holds the mask tight against the board.  While the board
and glass are "flat" they're not the same flat, so before parts of the
mask were up a bit, and the exposure was fuzzy, resulting in wider
and/or narrower traces - i.e. shorts and breaks.

> I thought the visual light would show something similar to what
> would be happening with the UV.

Yeah, similar, but consider that the UV is much more intense.  I'm not
sure you can rely on the light/dark pattern you see as a reflection of
what the UV is doing.  I suppose if I could find some day-glo
paper... ;-)

> I have found some superflux UV LEDs that have a viewing angle of
> 100+ degrees so I was thinking I could

Remember that the wider the angle, the more important it is to keep
the mask tight - angled light will get under the mask and expose more
than you intend.  You want the UV source to be as co-linear as you can

At 01:45 PM 3/30/2009, DJ Delorie wrote:
>The spacing was designed to take into account their
>UV pattern. Plus, I don't recall if that picture was taken before or
>after I went through and aligned all the individual LEDs.

hi, where do you obtain these LEDs. and how did you "align" them? 
looks like they are rigidly fixed in the plywood.


William Alford

GI Motility Medical Research Page
http://alford.grimtrojan.com/  

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

William Alford <walford@...> writes:

> hi, where do you obtain these LEDs.

"Best Hong Kong" on eBay, as suggested by others here in this group.
That was a while ago, though.

> and how did you "align" them?  looks like they are rigidly fixed in
> the plywood.

They're not that rigid, a little bit of bending pressure on the leads
can nudge them into alignment.  It's the leads that go through the
plywood, not the LED body.

--- In Homebrew_PCBs@yahoogroups.com, William Alford <walford@...> wrote:
>
> At 01:45 PM 3/30/2009, DJ Delorie wrote:
> >The spacing was designed to take into account their
> >UV pattern. Plus, I don't recall if that picture was taken before or
> >after I went through and aligned all the individual LEDs.
> 
> hi, where do you obtain these LEDs. and how did you "align" them? 
> looks like they are rigidly fixed in the plywood.
> 
> 
> William Alford
> 
> GI Motility Medical Research Page
> http://alford.grimtrojan.com/  
> 
> [Non-text portions of this message have been removed]
>


Hello All,
I don't know if these will work but I have 150 IR LEDs with these specs.

5mm IR Infrared LED 850nm

Emitted Color : Infrared

Size: 5mm

Lens Color : Water Clear

Forward Voltage (V) : 1.5~1.6

Forward Current (mA): 60mA Continuous, 120mA peak for 10% Pulse Width

wavelength (nm):850

View Angle: 15-30 degree.

If anyone is interested I am willing to sell them for a reasonable price. I can't use them.

Regards,
Dennis

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

From: "lineunderwaterservices" <neptune769@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, March 31, 2009 4:02 AM
Subject: [Homebrew_PCBs] Re: Led uv exposure box


> Hello All,
> I don't know if these will work but I have 150 IR LEDs with these specs.


They won't emit much UV. 8-)

Leon

--- In Homebrew_PCBs@yahoogroups.com, "leon Heller" <leon355@...> wrote:
>
> ----- Original Message ----- 
> From: "lineunderwaterservices" <neptune769@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Tuesday, March 31, 2009 4:02 AM
> Subject: [Homebrew_PCBs] Re: Led uv exposure box
> 
> 
> > Hello All,
> > I don't know if these will work but I have 150 IR LEDs with these specs.
> 
> 
> They won't emit much UV. 8-)
> 
> Leon
>
Yeah, I realized that after I sent the post. I had a brain fart. I don't know what I was thinking!!! Disregard post.

I found that you need 400-430nm for exposure of photosensitive pcb's, which is UV-a

:o)




--- On Tue, 31/3/09, leon Heller <leon355@...> wrote:

> From: leon Heller <leon355@...>
> Subject: Re: [Homebrew_PCBs] Re: Led uv exposure box
> To: Homebrew_PCBs@yahoogroups.com
> Date: Tuesday, 31 March, 2009, 4:14 AM
> ----- Original Message ----- 
> From: "lineunderwaterservices"
> <neptune769@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Tuesday, March 31, 2009 4:02 AM
> Subject: [Homebrew_PCBs] Re: Led uv exposure box
> 
> 
> > Hello All,
> > I don't know if these will work but I have 150 IR
> LEDs with these specs.
> 
> 
> They won't emit much UV. 8-)
> 
> Leon
> 
> 
> 
> ------------------------------------
> 
> Be sure to visit the group home and check for new Links,
> Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups
> Links
> 
> 
>