P
[email protected]
- Jan 1, 1970
- 0
I saw an discussion at:
http://www.diyaudio.com/forums/showthread/t-87555.html
Claiming an rebuilt scanner with 40 UV leds will properly expose an
pcb with the speed of 2cm/minute.
Known:
2 cm/minute
40 UV LED in line.
Assumed:
Scan area = A4 width = 210 x 297 mm
P_led = 3.8V*.04A (mentioned in the text)
t = 297/20*60
lambda = 400 nm
Math:
Q = 3.8 * .04 * t * 40 = 5417.28 Joule
A = .210*.297 = .06237 m²
PCB needs 86857 Joule/m² to be properly exposed.
Ignoring inefficiency of the LED, distance to pcb and it's beam angle.
If a board with each LED responsible for an 30 mm² area on a 100x160 mm board
is built it will need to shine for:
(.100*.160*86857)/(3.8*.040*60*((100*160)/(30**2))) = 8.57 minutes
Correct?
Especially how much energy is actually needed to properly expose an pcb board
photoresist..?
I'm interested in knowing practical numbers for this type of application.
And if the boards gets sharp?
Would pulsed UV led be more efficient?
More links:
http://hackedgadgets.com/2006/10/31/uv-led-pcb-exposure-system/
http://www.elektor-electronics.co.uk/default.aspx?tabid=29&forumid=5&postid=1369&view=topic
http://www.diyaudio.com/forums/showthread/t-87555.html
Claiming an rebuilt scanner with 40 UV leds will properly expose an
pcb with the speed of 2cm/minute.
Known:
2 cm/minute
40 UV LED in line.
Assumed:
Scan area = A4 width = 210 x 297 mm
P_led = 3.8V*.04A (mentioned in the text)
t = 297/20*60
lambda = 400 nm
Math:
Q = 3.8 * .04 * t * 40 = 5417.28 Joule
A = .210*.297 = .06237 m²
PCB needs 86857 Joule/m² to be properly exposed.
Ignoring inefficiency of the LED, distance to pcb and it's beam angle.
If a board with each LED responsible for an 30 mm² area on a 100x160 mm board
is built it will need to shine for:
(.100*.160*86857)/(3.8*.040*60*((100*160)/(30**2))) = 8.57 minutes
Correct?
Especially how much energy is actually needed to properly expose an pcb board
photoresist..?
I'm interested in knowing practical numbers for this type of application.
And if the boards gets sharp?
Would pulsed UV led be more efficient?
More links:
http://hackedgadgets.com/2006/10/31/uv-led-pcb-exposure-system/
http://www.elektor-electronics.co.uk/default.aspx?tabid=29&forumid=5&postid=1369&view=topic