I haven't seen these mentioned here yet - so I thought I'd mention them. Check out this link:
Marktechopto - Dorado LEDs
They are 7mm square SMT packages offered in Red, Yellow, Green, Blue, and White. I could find no thermal characteristics for the heat transfer of the package. They cost less than Luxeon LEDs (~$2), and so as you might expect have an acrylic lens (rather than silicone). I saw no life estimation, but I bet it would be the same as any other acrylic lensed high intensity LED. The emission pattern varies with the color of the device and is specified as 70deg for white, 100 deg for Y/R, and 140deg for B/G. I lit a white one up at low current and the beam is nicely even. It looks like they pour phosphor over the LED die like the Luxeon low domes, and there is a very thin ring of yellowish light that defines the edge of the beam. The colored LEDs have a very clean spot.
A few very interesting things about the LEDs' construction. Both the InGaAlP, and the InGaN devices have unique construction characteristics.
The white, blue, and true green LEDs have a single wire die connection right to the center of the die. There is a star shaped gold metal pattern on the top of the die to distribute current. The anode (+) connection is bonded to the heatsink mechanically and electrically. There is a small reverse polarity protection diode also bonded to the heatsink way off near the side of the lense, with it's own bond wire to the cathode (-) side. The die itself is very thin and is mounted on a cut off transparent pyramid. The polished heatsink is below this stack. When lit up, the thin die produced light on both sides. The light from the top is directly emitted. The light from the bottom is reflected though the cut off pyramid, off the heatsink, and out the bevel produced by the cut off pyramid shape. So I'm guessing the extraction efficiency is pretty good. The greenies produce up to 35lm, and the white up to 20lm.
The yellow and red have the most unique construction I've seen for a red/yellow InGaAlP device. They have four wire bonds at the edge of the die. There are two bonds for the cathode and two for the anode. The very opaque die is bonded to the heatsink mechanically (on the anode [+] side), but perhaps not electrically. The top of the LED die has two spiral metal tracks that begin at one edge and spiral to the center without being electrically connected. Each spiral has two bond wires to an electrical connection. As with the above devices, there is a small reverse polarity protection diode also bonded to the heatsink way off near the side of the lense with it's own bond wire to the cathode [-] side.
This is a different approach from the Lumileds flip chip wireless bonding, but neat to look at under a magnifier.
I like these /ubbthreads/images/graemlins/grin.gif. They might be my one watt of choice over luxeons given the price, even though they are less efficient. I've been looking for a cheap high power LED for general lighting tasks. I'm hoping the color and beam quality for the whites will be good. Above that I like the three watt Luxeons.
Marktechopto - Dorado LEDs
They are 7mm square SMT packages offered in Red, Yellow, Green, Blue, and White. I could find no thermal characteristics for the heat transfer of the package. They cost less than Luxeon LEDs (~$2), and so as you might expect have an acrylic lens (rather than silicone). I saw no life estimation, but I bet it would be the same as any other acrylic lensed high intensity LED. The emission pattern varies with the color of the device and is specified as 70deg for white, 100 deg for Y/R, and 140deg for B/G. I lit a white one up at low current and the beam is nicely even. It looks like they pour phosphor over the LED die like the Luxeon low domes, and there is a very thin ring of yellowish light that defines the edge of the beam. The colored LEDs have a very clean spot.
A few very interesting things about the LEDs' construction. Both the InGaAlP, and the InGaN devices have unique construction characteristics.
The white, blue, and true green LEDs have a single wire die connection right to the center of the die. There is a star shaped gold metal pattern on the top of the die to distribute current. The anode (+) connection is bonded to the heatsink mechanically and electrically. There is a small reverse polarity protection diode also bonded to the heatsink way off near the side of the lense, with it's own bond wire to the cathode (-) side. The die itself is very thin and is mounted on a cut off transparent pyramid. The polished heatsink is below this stack. When lit up, the thin die produced light on both sides. The light from the top is directly emitted. The light from the bottom is reflected though the cut off pyramid, off the heatsink, and out the bevel produced by the cut off pyramid shape. So I'm guessing the extraction efficiency is pretty good. The greenies produce up to 35lm, and the white up to 20lm.
The yellow and red have the most unique construction I've seen for a red/yellow InGaAlP device. They have four wire bonds at the edge of the die. There are two bonds for the cathode and two for the anode. The very opaque die is bonded to the heatsink mechanically (on the anode [+] side), but perhaps not electrically. The top of the LED die has two spiral metal tracks that begin at one edge and spiral to the center without being electrically connected. Each spiral has two bond wires to an electrical connection. As with the above devices, there is a small reverse polarity protection diode also bonded to the heatsink way off near the side of the lense with it's own bond wire to the cathode [-] side.
This is a different approach from the Lumileds flip chip wireless bonding, but neat to look at under a magnifier.
I like these /ubbthreads/images/graemlins/grin.gif. They might be my one watt of choice over luxeons given the price, even though they are less efficient. I've been looking for a cheap high power LED for general lighting tasks. I'm hoping the color and beam quality for the whites will be good. Above that I like the three watt Luxeons.
