Buying non full reels of LEDs is possible?

[Flyback]

Hello,
We wish to get LED lamps made by our PCB assembly place.
We realise that they will usually buy full reels of the Cree XP-E LEDs.

Though is it possible for them to buy the LEDs in say half or quarter full reels?.....eg, they may be able to get them cheap and only half-full off ebay, or it may be stock that is left over from a big lighting manufacturer such as Tridonic.

What I am saying is, is it possible for the PCB assembler to buy non-full reels of LEDs, that are somebody else's left overs?

 

[Nigel Goodwin]

Obviously it's 'possible', but it depends on someone else wanting to sell them at the same time you're wanting to buy, and finding each other.

I wouldn't have thought it's a very reliable process, why not buy a full reel and keep the rest for a future production run (or sell them on Ebay yourself)>

 

[ronv]

Many distributors will "reel them up" for a small fee to make the pc house happy.
Take a look at the mouse reel on the side of this link. This way you know what you are getting.

https://www.mouser.com/ProductDetai...=sGAEpiMZZMt82OzCyDsLFAkxDcivZzEmdl29bkW5rjg=

 

[jpanhalt]

Depends on how many and what you consider reasonable price. I bought several partial reels of common capacitors on eBay years ago. Most were almost full, but dated. It is probably a lifetime supply.

LED's are also available: https://www.ebay.com/sch/i.html?_tr....Xled+reels&_nkw=led+reels&_sacat=0&_from=R40 or, ranked lowest price first: https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=led+reels&_sop=15

John

 

[ronsimpson]

Digikey.com will make short reels. They will add blank tape to both ends. " digi reel"

 

[Flyback]

why not buy a full reel and keep the rest for a future production run (or sell them on Ebay yourself)>

we havent got space to store components.

Many distributors will "reel them up" for a small fee to make the pc house happy.

...that really worries me, because they could accidentally mix up the various bins of leds. The bin type is obviosly not marked on the led itself. W e have some parallel led products, and thus we need the leds to be the same vf group and indeed really from the same production batch

 

[ronv]

Yep, And just because your not paranoid doesn't mean everyone is not out to get you.

The bin number is on the reel.

 

[Flyback]

yes I appreciate that, but the poor £5/hr staff who do this job of sorting out the leds at the distributor's place may not pay too much attention to bin numbers....and why should they?, the bin numbers are not marked on the leds and so if they get it wrong , nobody will know.
Also, leds in parallel need really to be from the same batch....and if leds have been swapped around at the distributor's place then how do we know that one reel of leds is all from the same production batch? The production batch number is not marked on the reel, and it certainly is not marked on the leds.
The bin number is indeed on the reel, but if other leds have been swapped onto that reel from a quarter full reel elsewhere, then how do we really know if all the leds on the newly made up reel are really from the same bin?
I would say I would only trust the bin number on a reel if that reel was fresh from the led foundry itself.

I know it is not "politically correct" for me to suggest that people on low pay don't always pay attention to fine detail such as part numbers when they can get away with it, but I know of many workplace examples of this happening.

 

[jpanhalt]

(With respect to distributor made reels: )

I appreciate that, but the poor £5/hr staff who do this job of sorting out the leds at the distributor's place may not pay too much attention to bin numbers....and why should they?, the bin numbers are not marked on the leds and so if they get it wrong , nobody will know.

Your suspicions about DigiKey do not match my experiences. In 20+ years, I have never received a mislabeled part. Based on the appearance of the packaging and speed of shipping by DigiKey, I suspect the assembly of orders at DigiKey is highly automated and uses bar coding.

Now, of course, bar codes do have an error rate associated with them, but if you really must have 100% accuracy all of the time, you are in the wrong field.

Why would DigiKey take any small, loose component and reel it up? Assuming the component is available on tape, it seems more likely that they would buy the component on a reel and either cut the tape (DigiKey also sells "cut tape" versions), sell the reel, or sell a portion thereof.

DigiKey is the distributor with which I have the most experience. I have had much less experience with Mouser and Newark, but I suspect they also have similar levels of automation and accuracy.

John

 

[Flyback]

thanks but i'm not speaking about leds received from digikey. I am speaking about PCB assembly houses sourcing components from the cheapest possible place in order to get our PCBs built.......for example, if a big company like tridonic had a load of quarter or half full reels of leds that they were not using, they may seek to sell them back to the market.............my PCB assembly house may pick up on this and buy some such leds..........there is the danger that they may not bother to source the exact right bin number of led....and that could cause problems with our parallel led connection.

 

[ronv]

They could still do that from Cree. Lets say the lead time was 3 months for your bin number but in stock for another... well....
If you don't trust your vendor buy your own parts and consign them. They would probably like that.

 

[alec_t]

As part of your written contract with the PCB assembly house you should specify that all paralleled LEDs as assembled will be from the same batch/bin. It is then their responsibility to source/assemble the LEDs appropriately. Make it clear you won't pay for any non-compliant assemblies.

 

[Flyback]

Make it clear you won't pay for any non-compliant assemblies.

when the assemblies are made, there is no way of knowing whether or not leds from the correct bin, or all from a single bin, have been used, because the leds are not marked with the bin code or batch code........if products (which contain paralleled leds) are comprised of 'rogue' leds from various different batches and bins then the product will likely pass the quick production "lamp on/off" test but will fail prematurely in the field.....and when it does fail in the field, we still couldn't be sure if this was due to the wrong bin of leds being used (or a mixture of led batches/bins) , because we wouldn't know this, as the leds themselves are not marked with the bin code.

There is a danger when sourcing leds from a distributor because as we discussed, an ordered "lot" of leds may contain leds from all kinds of different batches, andthese wouldn't be suitable for parallel operation.

If you don't trust your vendor buy your own parts and consign them.

this is the best idea I have heard...though it sounds like an extra pain for our procurement staff.......I can see them running round like idiots trying to source x number of leds from the same batch/bin......

 

[ronv]

They have tons of bins. Just spec the bin code.

**broken link removed**

 

[Flyback]

yes I agree, and that's part of the problem....in UK , its touch and go whether any particular bin will be available on a reasonably short lead time............meaning procurers are more likely to take "short cuts "

 

[ChrisP58]

I seem to recall a discussion from a few months ago about the pros and cons of using LEDs in parallel.

It may be OK in theory, but can be a headache when you get to the realities of production.

 

[Nigel Goodwin]

I seem to recall a discussion from a few months ago about the pros and cons of using LEDs in parallel.

It may be OK in theory, but can be a headache when you get to the realities of production.

And after all the fuss flyback has made about it I'm amazed he's even considering it?