After a lot of tries and not well printed boards with Exposure Box V1 i ended that the problem was the light diffusion (btw my Workbench Power supply 0-30Volt 0-3A was printed on this box with very good result ). And there came the idea of building another new one UV box, hacking an existing scanner box. Scanner box is perfect for this job with a glass installed and a plastic cap. I replaced all the mechanical content of the scanner with 5 blacklight lamps and a home made timer making my life easier while waiting for the pcb exposure.
The first look
I added a 220V switch and a 220V power plug
Opening the cap you can see the five blacklight lamps
Here is my Workbench Power supply 0-30Volt 0-3A film
An inside look. For adjusting the distances between the lamps and keeping them stable i cut and put styrofoam covered with aluminum foil. Also the background is a cardboard covered with aluminum foil.
Here i soldered the cables on the back side of the pcb because the drill holes were big and destroyed the routes. Also the white cable replaces a not well printed route as the green one.