Finally, I did a first test run. Exposure was done with 400 nm LEDs. Basically, once completed the exposure unit will look similar to this one: http://www.fdm-ware.de/UV-Led/index.html
So far I did just one of the three strip boards with 24 LEDs on it. I was too lazy
I ended up with a 20 min exposure at a distance of about 20 cm, though 10-15 min should be fine too.
All in all I'm pretty pleased with the result.
The white dots is some dust I didn't clean off before doing the picture.
Cool thing is that once etched you can wipe the surface with acetone or whatever you want. The black colour will never get off.
I'll probably give it a try to see how it looks with a thin clear coat.
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Structo wrote:What is the material used for the black?
So this is similar to making a printed circuit board right?
It's black anodized aluminium with a photsensitive layer on it. Only difference to PCBs is that developing (removing exposed laquer) and etching (removing the black anodized layer) below is both done in one step, in 1% sodium hydroxide. Through etching the the bare aluminium below the black anodized layer is exposed giving you silverish-whiteish letters on a black background.
Hi.. looking good!
Did you copy directly from a positive printout, or did you reverse to a negative?
( - The Bungard paper i not clear on this point...)
Aurora wrote:Hi.. looking good!
Did you copy directly from a positive printout, or did you reverse to a negative?
( - The Bungard paper i not clear on this point...)
I used a positive print on inkjet overhead transparency. So, what's black on the print is black on the Alucorex.
Would be interesting to see how black letters on bright background look....
You probably could use daylight if there are no clouds and light intensity is somehow constant between your exposures.
Here in Vienna/Austia I had to wait until May or June
Overexposure up to a certain amount isn't that critical, underexposure is because the photosensitive laquer doesn't get off.
You could however use a strong lamp (e.g. 500W) and move it a bit further away (~ 1m) so light intensity is somehow homogenous over the whole face plate.
Some years ago I used a standard writing desk lamp for exposing my PCBs. It took an hour or so but it worked nicely.
The photosensitive laquer on Alucorex is most sensitive in the range of 400 nm. Therefore 400 nm LEDs are optimal.
Aurora wrote:LEDs are OK, but the tubes will give you an exposure time of appx 3 mins for 3 tubes spaced about 10 cm......
Sounds good and should be less work than to solder 50 more LEDs and resistors.
Will check it out. So far I don't have any idea what stuff is needed besides the tubes for wiring them....
Any regular cheap household lamp for two 50 cm tubes will do, - typical kitchen lamp. - Or a parallell set of single units, as many as needed. Can't point you any further vis. any austrian suppliers...
My PCB box uses 6 lower and 6 upper covering appx 45x60 cm double sided panels.. Light to plate distance is about 10 cm, normal exposure time 2-2.5 mins..... The tubes I use is a Philips TL20-05
Bungards " Helios" lamp is the same stuff, - ours is another make, though....
Thanks a lot! Will have a look.
What kind of glass did you use for the covers?
The glass plate I bought is just standard window glas. Doesn't seem to reduce light intensity at 400 nm.
Plain glass is OK, but the dedicated PCB boxes uses a corrugated plastic sheet for vacuum cover, to ease the air escape.
Just changed ours ( to many scratches), but my national supplier worked seemingly hard to find this plastic sheets. In the end I think it actually came from Bungard, though.....
