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PCB photo etch measurements/guide: (2007.05.10:1 pcb#7 tech_notes2#6)

1] Using foggy/tracing paper (Artoz Perga Pastel) gives better results than Folie 3562 Overhead transparency when printed with laser printer (600 dpi) though latter can be used if fill in gaps. (SMD/T fine with five minutes below).

2] Warm-up UV lights (see pcb below) for two minutes. Switch off briefly and line up with ink facing PCB (in dim daylight is fine). Expose tracing paper for five minutes/ overhead transparency for two and a half to three minutes (heavy books on scanner/UV box lid). Develop for three to five in the Natriumhydroxid (Sodium Hydroxide I think (10g in 1000ml)). Wash in cold water. (above in dull light).

3] Now etching in Natriumpersulphat (Sodium Persulphate) which is faster, cleaner and more accurate. Dissolve 120g in 600ml water. Heat up in bath to 40 degrees or more. Etch board for around 15 minutes until copper vanishes - agitating as much as possible. Wash and dry boards and save solvent removal of UV paint until just before soldering.