How do i know LEDs are genuine?

[grizedale]

If i buy a batch of LEDs that are Cree or Osram, or any other type, how do i know that they are really that type?

How do i know that they are not cheap, fake imitations from some unknown company?

LEDs, and other components , are almost never supplied by the manufacturer, they are supplied by a network of distributors, do we know that all there components are genuine.

If they are all genuine , then how do we know that?



Why is is that components for SMPS's for military use undergo vast amounts of component testing?......is it because they are worried that they may be fake components, not up to standard?

 

[Pjdd]

If i buy a batch of LEDs that are Cree or Osram, or any other type, how do i know that they are really that type?

How do i know that they are not cheap, fake imitations from some unknown company?

LEDs, and other components , are almost never supplied by the manufacturer, they are supplied by a network of distributors, do we know that all there components are genuine.

If they are all genuine , then how do we know that?

There's no way to be 100% certain. If they are supposed to be from a reputed manufacturer but they are of poor quality - like a high failure rate, low brightness, etc., then they could be fakes. But there's no way to be sure.

Why is is that components for SMPS's for military use undergo vast amounts of component testing?......is it because they are worried that they may be fake components, not up to standard?

It's not just with SMPS components, but with most products for the military. Such products are likely to be used under very harsh conditions like extremes of weather and they have to endure heavy shocks and bumps. Failure of a single component could literally mean disaster.

Suppose you were a soldier under enemy fire and you tried to call for help with a radio. The radio might have been bumped when you dived for cover, or it might have been exposed to mud, moisture or a hot sun. If it failed due to a component failure, you could lose your life because you couldn't call for support. That's just one of many many possible scenarios in which component reliability plays a crucial role.

 

[KerimF]

The simple test for LEDs is to measure the forward voltage of a number of similar LEDs at a certain current (their supposed rated current for example) and find out the differences. Usually, the smaller the differences are, the better the LED quality is.

Added:
If the range of the measured voltages is reatively wide you can be sure the LEDs (of the same lot) are of low quality even it is confirmed otherwise. For example, once I got samples (standard red LEDs rated @20mA) which had a range of 1.8V to 2.4V. The ones I have imported from serious companies in China can have a forward voltage of 1.93V +/- 0.03V @20mA.

 

[dick_freebird]

Why is is that components for SMPS's for military use undergo vast amounts of component testing?......is it because they are worried that they may be fake components, not up to standard?

The military demands, and is willing to pay for 100% certainty,
and does business through elaborate specifications aimed at
getting just that. Whereas your consumer market will gladly
take "just good enough" to some confidence level, in order to
get to the right price-point in volume production. In between
you have stuff like automotive / industrial, where you may
actually perform testing of packaged units at more than one
temperature, etc. but not likely the Group _ testing pertaining
to package integrity and abnormal conditions.

You might inspect a sample LED for a manufacturer's logo.
You could purchase a sample from the manufacturer directly
and use it as a comparison for physical construction. Most
of the major components distributors are all spun up now
over "counterfeit" parts and should be pretty trustworthy.
It's the lower tiers and private brokers that are most likely
to engage in substitution, rebranding, refurbs.

 

[grizedale]

i think shipping docs could be forged (?)