Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hi group

Last summer I created a UV LED based exposure unit with which I had IMHO
very good results. I uploaded a description and pictures to the
following place in the files section:

Files </group/Homebrew_PCBs/files/> > Homemade_PCB_equipment
</group/Homebrew_PCBs/files/Homemade_PCB_equipment/> > UV LED exposure unit

Below you find the descriptive text for your quick reference - enjoy!

Markus

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UV LED exposer unit
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In this folder you can see pics of my homebrew, UV LED based double side exposure unit. The folowing features are maybe "special" enough to be noted:

- It generates very PARALELL light. This is important if you want to make small traces. Using this unit, I already sucessfully created boards with 5 mil traces using dry film fotoresist.

- There are two holes in each glass allowing the positioning shafts I use to allign the films against the PCB to remain. This allows me to leave the protection foil on the dryfilm resist, resulting in almost no wear out on the films.

- Obviousely this unit allows to expose both sides of a PCB at the same time. To do this, the upper box is simply placed on top of the lower. The glass is intentionally NOT mounted to the boxes. This allows me to fimrly press the two glasses together thereby makeing sure there are no air bubbles.

- The LED distance is 20mm square, distance from the LEDs to the PCB is ~65mm

The exposure time is longer than what's normal with tube oriented units. I'm almost exclusively working with dryfilm resist due to it's several advantages. There the time is exactly one minute.

Feel free to ask questions, otherwiese enjoy :-)

Markus