Homebrew PCBs

Hi There,

I've been creating my own pcb's for a while now using photosensitive
boards and a uv light. My current uv light consists of a old scanner
with three uv tubes in it. I'm currently looking to rebuild it and i
found this website :

http://www.prototrains.com/etch2/uv1.html

This looks like a nice unit, but I don't understand what the grid
between the light and the boards are for? Won't it break the light
going to the board ?

Any other ideas on possible improvements for a uv exposure unit while
I'm redesigning?

Thanks,
Tom

Tom,

The author explains the grid by stating in his article ...

"a light source for exposing the photoresist: it must be collimated 
enough (i.e. the light rays must be parallel) to avoid optically 
undercutting the artwork".

Cheers,

Ross

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

From: "Tom Van den Bon" <tvdbon@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, May 27, 2008 11:37 AM
Subject: [Homebrew_PCBs] UV Exposure Box


> Hi There,
> 
> I've been creating my own pcb's for a while now using photosensitive
> boards and a uv light. My current uv light consists of a old scanner
> with three uv tubes in it. I'm currently looking to rebuild it and i
> found this website :
> 
> http://www.prototrains.com/etch2/uv1.html
> 
> This looks like a nice unit, but I don't understand what the grid
> between the light and the boards are for? Won't it break the light
> going to the board ?

I think it helps to collimate the light.

Leon
--
Leon Heller
Amateur radio call-sign  G1HSM
Yaesu FT-817ND transceiver
Suzuki SV1000S motorcycle
leon355@...
http://www.geocities.com/leon_heller

Tom,

You can find pictures of the LED based exposure unit I built in the 
files section of the group.

Honestly, these days I really would no longer bother building one with 
tubes especially considering the truly low prices of sources like 
besthongkong.com

(Note, I'm not related to them. Just bought 1'000 UV leds for ~$120.- 
and I'm happy with them)

Markus

Tom Van den Bon schrieb:

>
> Hi There,
>
> I've been creating my own pcb's for a while now using photosensitive
> boards and a uv light. My current uv light consists of a old scanner
> with three uv tubes in it. I'm currently looking to rebuild it and i
> found this website :
>
> http://www.prototrains.com/etch2/uv1.html 
> <http://www.prototrains.com/etch2/uv1.html>
>
> This looks like a nice unit, but I don't understand what the grid
> between the light and the boards are for? Won't it break the light
> going to the board ?
>
> Any other ideas on possible improvements for a uv exposure unit while
> I'm redesigning?
>
> Thanks,
> Tom
>
>

Tue, 27 May 2008 10:37:39 -0000, you wrote:

>Hi There,
>
>I've been creating my own pcb's for a while now using photosensitive
>boards and a uv light. My current uv light consists of a old scanner
>with three uv tubes in it. I'm currently looking to rebuild it and i
>found this website :
>
>http://www.prototrains.com/etch2/uv1.html
>
>This looks like a nice unit, but I don't understand what the grid
>between the light and the boards are for? Won't it break the light
>going to the board ?

A little.  It looks like it's trying to minimize off axis UV, so the
UV is mostly perpendicular to the board.  That and perhaps a little
diffusion,

I have 4 UV longwave lights that I've used.  They seem to work well.
I've got a modified vacuum frame for single sided exposures.

Doing DS toner transfer, though, for now.

Harvey

>
>Any other ideas on possible improvements for a uv exposure unit while
>I'm redesigning?
>
>Thanks,
>Tom
>