Maker Pro
Maker Pro

LEDs at the die level

sophie MC

Aug 26, 2013
3
Joined
Aug 26, 2013
Messages
3
Hey guys,

I need to found a LED, SMD type, with very small dimensions (for example, package 0402 or 0603) that produces high power output.

I read about LEDs at the die level, but I don't understand what does "at the die level" means. Are they a good choice?

Can any one help me with this???

Thank you so much for any information at all
 

GreenGiant

Feb 9, 2012
842
Joined
Feb 9, 2012
Messages
842
They are just talking about what size they are made.
For example an indicator LED may have a typical die size of 250 microns, meaning when it is made it will be about 250 microns across.
 

davenn

Moderator
Sep 5, 2009
14,254
Joined
Sep 5, 2009
Messages
14,254
what's your definition of hi power ?
as in what wattage are you needing ?
very small and hi power out don't go together too well as the hi power LEDs require a substantial heatsink

Dave
 

sophie MC

Aug 26, 2013
3
Joined
Aug 26, 2013
Messages
3
Thank so much for answering.

What I need is a LED with an optical power output of 100 or 150 or 200 mW/cm2. I know that this values in mW/cm2 depend on the area and that if I have an area of 1 cm2, to obtain 100 mW/cm2, I need a source of 100 mW. If I have an area of 50 cm2, to obtain 100 mW/cm2, i need a source of 5 W, and so on. My problem here is that I don't know the area because I think that the area depends of the beam area of the LED. Is this right?
Another problem is that I have to soldering the LED in a very small space (like, 1.5 mm x 1.5 mm) in a PCB.

Imagine that I have this LED: http://doc.chipfind.ru/osram/f1998a.htm

The information of optical output comes in lumens. How do I know what is the optical output in watts? Is this LED suitable to soldering in a PCB? What is the area the the beam of this LED can illuminate?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
Input power is in watts, output intensity is in lumens.
 

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
That chip is .3mm(.0118 in) square! And it has contacts on top and bottom. I don't think you could possibly find a way to use it.

What are you trying to build? (I think I know already, a device for doing skin treatments, right?)

Edited: too many zeros in my inches. About 1/100 of an inch.

Bob
 
Last edited:

sophie MC

Aug 26, 2013
3
Joined
Aug 26, 2013
Messages
3
I am trying to built a device for doing skin treatments. I have a batery of 3V and 160 mAh. The device is small and as I said I have litle space to put the LEDs for illuminating tissue. The light source has to have some output power so it can penetrate into tissue.
I think that output power from LEDs can be in watts to. It is call radiant flux in watts and luminous flux in lumens. When I am refering to watts I'm not refering to the power that is consumed by de LED but the power radiated by the LED that is gone to penetrate in the tissue.

I have read something about to use LEDs at the die level for my aplication. They refer to a silicon diode in forward bias in series with the LED should be sufficient. But I don't urderstand wath they want to say with this.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
Radiant flux for LEDs is maybe 5% of the input power.

Actually it is quoted as being between 4.2% and 35%, although in practice they are only slightly more efficient than CFL.

"Using LEDs at the die level" is a fairly meaningless statement unless you're a manufacturer of the LEDs themselves. Even COB LED's come with a substantial substrate and a protective (and possibly phosphor) coating on top.
 
Top