Do not look into 12 Watt UV lamp with remaining eye

We’ve seen a couple of UV lamp builds for exposing photosensitive PCBs and erasing EPROMs, but [John] over at decided if it’s worth doing, it’s worth overdoing. They designed a UV exposure board using twelve 1 Watt UV LEDs, an impressive amount ultraviolet light that you probably shouldn’t look at for too long.

We’ve seen UV exposure boxes before, usually made with a bunch of 5mm UV LEDs soldered to a piece of protoboard. These projects do their job, but the exposure time is on the order of minutes. The UV lamp can expose a PCB in just 20 seconds.

The build began with four pieces of aluminum bar, 1 inch wide and 1/8″ thick. The 12 star LEDs were glued down to this bar with thermal adhesive and serve their purpose as a rather large heat sink.

[John] performed a little test to determine how long it would take this monstrous UV source to expose a PCB. By copying a PCB mask four times and placing it over an unexposed board, [John] made a PCB with exposure times of 60, 45, 30, and 15 seconds. After developing and etching, all but the 15-second exposure was fully etched, an amazing result that will probably lead to some very, very rapid prototyping.

All the more impressive is the fact that only four 1-watt LED drivers were used for this build. That’s right, this UV lamp is actually operating at about a quarter of its maximum rating, or about 285mA per LED. We’d hate to see this thing operate at full power, protective eyewear or not.


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