the
versus
Look up
Also I was under the impression that white leds are actually blue leds with a phospher coating in the epoxy ......
also might want to try
also you might want to google "cheapest white leds" and see where that leads........
the
versus
Look up
Also I was under the impression that white leds are actually blue leds with a phospher coating in the epoxy ......
also might want to try
also you might want to google "cheapest white leds" and see where that leads........
-- Because people will pay that.
Does anyone know why white LEDs are so expensive? Looking through the Mouser catalog, I noticed that $2 a piece is a cheap as they get, versus $0.10 for Red/Green/Yellow. Why is that?
An immediate reason is that Red LEDs have been around for at least 35 years, with green and yellow following soon after, while white are still relatively new. It takes time for things to ramp up so production can reduce costs, and for there to be demand which also drives prices lower.
And while I have no idea how it affects cost, each of the colors of LEDs use a different scheme. White LEDs took so many decades to arrive after the original LEDs because they had to figure out how to make them (same with blue LEDs); it's not a minor change for every color. There may be something about white LEDs that cause a higher price, even taking out of the equation the early price of any device.
Michael
Not only that, but the blue LEDs have now been around for quite some time, along with UV. Yet, they are still considerably more expensive. People don't use these if they don't need to. Also, my local electronics supplier tells me that, at least in the case of the blue LEDs, they actually do cost more to produce. One could ask if this is material costs, equipment, higher rejection rate, etc. It would be interesting to compare the manufacturing methodolgy for these different LEDs, and also their photodiode detector counterparts.
Dominic
Whites, I believe, use fluorescence in order to generate the apparent white. Since fluorescence is almost always towards longer wavelengths, they require blue led technology to generate the primary source of energetic photons which then stimulate the fluorescent responses in the rare-earth materials. Blue leds are more expensive to begin with, partly because the processes they use are "difficult" and partly because Cree, I believe, has a patent on one of the key wafer types often used (silicon carbide?) and anyone using that technology has to pay a higher than usual price for access to it.
I suspect that many of the applications which would otherwise consider the use of blue leds for aesthetic purposes (product sales) don't believe that blue counts for enough additional value in their products to be worth the very high cost, so they use other colors that are much cheaper and live with it. So the volume on blue doesn't pick up that quickly, on its own legs. So, probably, the price of blue leds is being more driven by the white led usage and that itself is more driven by flashlight sales, I'd guess.
That's just my own meandering and I'm probably wrong on several counts, at least. It may also be that there is a perceived value to white and that the number of players is small and the market 'controlled' to a sense (at least to the degree that Cree controls it), but I've no idea about that. In any case, they are more expensive.
Perhaps Don K. will chip in here and inform us all about it or provide a link to a web site that does.
Jon
Fools! If they started with white, they could easily make other colours with a filter! :)
-- Danny
And doesn't white need lots of wavelengths whereas red just needs one?
Yes, that's true. And anywhere one can get both blue and white LEDs, white ones don't cost much more than blue ones do.
Blue LEDs do indeed cost more to make than red, orange, yellow and yellow-green. I believe that a major reason is that the chip "substrate" is artificial sapphire (aluminum oxide), except in LEDs by Cree where the substrate is silicon carbide. The working layers of blue LEDs are gallium nitride and/or indium gallium nitride, and those do not work well on the longer-established LED chip substrates of gallium arsenide and gallium phosphide. Apparently the trouble with putting gallium nitride on gallium phosphide is an excessive difference in the spacing between atoms - aluminum oxide and silicon carbide provide a better match in that area. And artificial sapphire and silicon carbide apparently cost more than other substrates because they are so much harder and maybe also because of higher melting points.
- Don Klipstein ( snipped-for-privacy@misty.com)
Brian wrote in news:Xns95DB87400801Cnonenonecom@24.93.43.119:
Supply and demand. I just recently went to ebay and got 50 11000mcd white LEDs for about $12 (+$5 s/h from hong kong). There are cheaper places than mouser or digikey right now but you might have to wait an extra week to get them
-Ray
I just got a keychain LED flashlight at Walgreens that was only $0.99, so the white LED it has must be cheaper than $2 since I got a case and an on button and a battery while I was at it :-).
But of course, a key use for white LEDs is for flashlights, and one can see quite a variation between cheap and expensive.
I bought one LED flashlight a couple of years ago, in about the same package as those cheap laser pointers. It seemed to put out decent light (and the neat thing about those was they used three button cells, that were also used in the cheap laser pointers, and the latter were even cheaper so a source of batteries).
But two weeks ago, I bought a white LED bicycle headlight, because it was only fifteen dollars. That thing has way more light out of it, and it may be brighter than an 2AA Maglite.
Michael
Because the bicycle headlight uses a LED driver the and a high MCD intensity.
I also source my LED's from Ebay, the white ones from UBIDITNOW are a very good price. $33 for 100 10000mcd whites, inclusive of shipping so that's only 33cents per LED. They are doing 20,000mcd leds for $79 inclusive of shipping too. I do find them to be a little on the flaky side sometimes though. I use these LED's for making a small (15 LED) front lamp for use on a motorbike. I just use a very simple cct to run these in groups of 3 with a single current limiting resistor for each group of 3. I find that every now and then one LED will blow :( I guess you pays your money and takes your choice.
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