5mm LED fade test, Nichia vs China

The company where i work uses leds for all sorts of projects. We have all sorts of customers, some want the lowest price, some want good quality stuff and others want both. Anyway, one needs to know what he is selling so i had a friend of mine test the lifetime of the leds we use for "cheap" projects and those we use for "high quality" projects.

Test:

Nichia White 5mm LED, 44000mcd, 10°, 20mA, NSPW500GS-K1-b1/b2-V/W
vs
Superbright White 5mm LED, 13000mcd, 20°, 20mA which is (as far as i know) one of the "best" 5mm leds from China.

Equipment: Optronic-Lab OL 770-LED Spectroradiometer
Test duration: 1360 hours
Forward current: 20mA
Ambient temperature: start 28°, 668h: 28°, 1340h: 31°


You noticed that the brightness of Nichia actually went up which i thought was strange. My friend told me its typical for Nichia leds: brightness goes up around 10% in the first 5000 hours. He also said that 20mA or 30mA wont affect Nichia that much but he is unsure about other leds.

ps: the purpose of this topic is to share what we discovered. It doesnt say buy this or dont buy that but only show the difference between at 10 cent led and a 90 cent led". What you do with this info or what you buy its your choice.

AT what mA will this Nichia attain 44,000mcd? Nichia rates their 5mm's at the highest allowable mA for that particular LED?

Bill

That is interesting result!! But what might be the reason for the better performance of Nichia. I have always think that one of the biggest reason for fast fading in 5mm leds is the epoxy, but maybe its not like that....

I'd like to see that same test performed with one of the Cree 5mm leds.

The 44000 mcd are probably measured with millisecond pulses like most other LEDs.

space

The Nichia led may not be the 44,000 mcd bin, they supply 3 bin options per led and off course you cant choose...

Juctuc said:

That is interesting result!! But what might be the reason for the better performance of Nichia. I have always think that one of the biggest reason for fast fading in 5mm leds is the epoxy, but maybe its not like that....

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There are several reasons for lifetime difference:

1. Most important: The Chip. Cheap Chips have a very fast degradation. Using them at much lower current <10mA can improve the lifetime A LOT. So you might say they are " overclocked ". They are not actually useful for use at 20mA.
2. The Phosphor: Cheap Phosphor layers of chinese producers tend to be destroyed after only few thousand hours.
3. The epoxy: Thats the smallest of all reasons and only is interesting if the LED lasts 10-20k hours and more. At lifetimes this long the epoxid will start to get diffuse if it aint good.


Yes Nichia has 3 bins for the GS and is not known from which bin the led was.

ledstein said:

There are several reasons for lifetime difference:

1. Most important: The Chip. Cheap Chips have a very fast degradation. Using them at much lower current <10mA can improve the lifetime A LOT. So you might say they are " overclocked ". They are not actually useful for use at 20mA.
2. The Phosphor: Cheap Phosphor layers of chinese producers tend to be destroyed after only few thousand hours.
3. The epoxy: Thats the smallest of all reasons and only is interesting if the LED lasts 10-20k hours and more. At lifetimes this long the epoxid will start to get diffuse if it aint good.

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4. How the die is mounted: Poor thermal coupling to the lead frame will result in higher operating temperatures and shorter lifespan.

I personally suspect that the chip and the mounting methods are the biggest reasons why most Chinese LEDs have short lifetimes at 20 mA. That being said, for lots of uses these LEDs are fine. Just think of them as 5 mA LEDs instead of 20 mA. For many of my projects I'm going to use a lot of LEDs anyway just for even lighting. In many cases it actually looks better using 2 or 3 times the number of LEDs, and driving them at 5 mA instead of 20 mA. Remember that you can get 10 or more Chinese LEDs for the typical price of one Nichia. Nichia also has its uses, especially in applications where you only have room for one or a few LEDs, and need to drive them hard as a result.

BTW, thanks for these results. Any plans to extend the tests out to, say, 10,000 hours or more? It seems Nichia may have solved the lifetime issues which it had a few years ago where even their 5mm LEDs were dimming to 50% after a few thousand hours (see here).

Nice test! Was there any color shift? I'd expect some color shift with the brightness increase. Anyways. good performing LEDs for long term use.

The testing is continuing and i will post results at 5000 hours.

Its true Chinese LEDs can be used very well in most applications you just need to know how to use them correctly!

I will ask about color tint.

Luminous intensity goes up? :thinking:

Now we'll start having "burn-in" regimens for our flashlights! :laughing:

ledstein said:

The testing is continuing and i will post results at 5000 hours.

Its true Chinese LEDs can be used very well in most applications you just need to know how to use them correctly!

I will ask about color tint.

Click to expand...

Any update on this? 5000 hours should have elapsed by now. Thanks!

At 20ma, the GS will probably go for 15K-20K hours. He needs another year or two to complete the test.

His cheap Chinese LEDs did better than mine!

So far, at 30ma, the New Cree LEDs will outlast the GS.