Chinese LED chip remplacement

[Mkala]

Hello all :wave:

Nowadays a lot of lighting products have LEDs inside, and price come cheaper. One common problem I found is they are often made with with 1w and 3w cheap LED "bead" made in china... with a poor reliability. Someone know a good manufacturer that make a chip that is physically compatible ? AFIK, Cree or Lumileds does not have these footprint for their LEDs...

It looks I can't add an attachment to my post, here is a picture of chip LED I am talking : http://image.made-in-china.com/43f34j00SKvQjbHFMhoV/High-Power-1W-LED-Chip-12V.jpg

Thanks a lot for any advice, almost sure I am not alone with poor quality LED chips in common products.
See you

 

[ssanasisredna]

Hello all :wave:

Nowadays a lot of lighting products have LEDs inside, and price come cheaper. One common problem I found is they are often made with with 1w and 3w cheap LED "bead" made in china... with a poor reliability. Someone know a good manufacturer that make a chip that is physically compatible ? AFIK, Cree or Lumileds does not have these footprint for their LEDs...

It looks I can't add an attachment to my post, here is a picture of chip LED I am talking : http://image.made-in-china.com/43f34j00SKvQjbHFMhoV/High-Power-1W-LED-Chip-12V.jpg

Thanks a lot for any advice, almost sure I am not alone with poor quality LED chips in common products.
See you

If you are buying anything with that package for the LED, it is likely really old .. or made with surplus LEDs. Almost no one, including Chinese companies would use that package any more. It is way too expensive.

 

[Mkala]

Yes, but my idea is to replace just LEDs, it easier than finding MCPCB for each application. But as I understand no good led maker will sell LEDs of this shape now ? Don't has to be top performer, reliability and light quality is more my concerns.

Quite sure I will found same LED chips in a lot of product in the future, it just started now with 3-4 years old products failing out of warranty.

If someone has a bright idea ?

 

[snakebite]

those are luxeon clones.
the ones availible on ebay are quite good.
most failures i have seen is lack of contact to the heatsink/mcpcb.
leds with a gap and no compound under them.i have fixed several mr16 bulbs that had this issue.3 new,unabused leds and some heatsink compound.
i just spring the leads slightly and solder them down while holding the lead with a toothpick.i have 2 in desklamps with over 20000 hours on them with no noticeable loss over an unused control.
your 4 year old leds probably were not the best thats why i replace all 3.the ones i got a few months ago are much more efficient.less heat more light for the same power.
they will do fine with jbweld as the compound.mounting and heatsink compound in one.
dont try to reflow solder these.most dont survive that.

 

[Mkala]

Thanks a lot for information, it's kind to spend some time to help me

Yes but these Luxeon are phased out from long time ago... I still have an old one, pins looks reversed however.

I had the same experience : lack of thermal paste so died quite quickly in a few MR16 I repaired. But I'm quite surprised you recommend to avoid solder reflow : it's the best way to assure thermal transfer.
Here come the reason of death for these LEDs I think : the die is not properly glued on base, or with cheap glue. This mean temperature (functioning with lack of cooling/thermal transfer or reflow soldering) will break them. On the last I repaired, pushing on the top of lens made temporary contact....

However, in the past I repaired a few MR16, build a fixture with 4 of them (but are not really used a lot to be honest) and changed the 3 on last project... all at reflow, and no death. At least at start, not a lot of hours on them...

I made more research, and on ebay you can buy standard and Epistar one. Do you think the last are better and it is worth to buy them ?

Thanks again

 

[snakebite]

the ones i have are epistar and have huge dies in them.
your theory about the die attachment being poor may be true.
when i tried reflowing them the die attachment failed.bright for a second then dim blue.
jbweld(steel filled epoxy)or compound and springing the leads work fine.

 

[Mkala]

Thanks for your reply

Ok fine, I ll try to buy epistar and see if they works good and happy with reflow soldering.
If not thermal glue/paste will do the job.

Yes, it's only my theory, I'm not specialist in chip manufacturing and assembly, but something is wrong, for sure

 

[ssanasisredna]

Thanks for your reply

Ok fine, I ll try to buy epistar and see if they works good and happy with reflow soldering.
If not thermal glue/paste will do the job.

Yes, it's only my theory, I'm not specialist in chip manufacturing and assembly, but something is wrong, for sure

Epistar makes LED die not packaged LEDs in this form factor so there is no way to know the quality of a LED being called Epistar brand.

 

[Mkala]

Epistar makes LED die not packaged LEDs in this form factor so there is no way to know the quality of a LED being called Epistar brand.

Yes, but at least I have a good die.. lol
I know it does not solve the overall quality problem of these chip. If you have any idea to buy quality one, please let me know, thanks

 

[ssanasisredna]

Sorry don't waste my time on stuff that old. Cheaper when you include shipping to just buy something new. Some of those are isolate base, some are not. Some are reversed polarity. It's not worth your time and hassle.

 

[Mkala]

I think you should take time to read more carefully. I don't do anything new with these kind of LEDs, just repairing thing that are made with. It's more complicated to find MCPCB that fit in application, if not impossible in many case.
It's not my choice, it's the one of manufacturer. And my choice is to repair them as I can

For building new things, I use well known good quality LEDs from Cree or Luxeon.

 

[ssanasisredna]

I understood. There are times when it is just easier to throw the whole thing out and buy new ones as the technology has changed so much.

The only "reliable" suppliers of those LEDs were Lumileds, Seoul and Edison. Seoul kept improving it for a while, Lumileds ditched it a while ago. Edison somewhere in there. There is nothing quality left unless it is old stock.

 

[Mkala]

You are right, sometimes it's not worth it repairing, electronics and LEDs goes forward fast.
But I think we are throwing out too much things. Of course, quality is not always here -> so DIY is perfect way to do good a reliable things, because when you buys things you can buy quality, does not matter if it cost 1$ more And reward a lot of satisfaction

 

[snakebite]

my ebay leds are edison opto.
probably not cree,nichia,or lumileds level but good enough.

 

[Julian Holtz]

I also replaced such LEDs recently, but because of color tint. On the new LEDs, I bent the legs slightly upwards, about 0.5mm above the base. I cleaned the solder pads with solder wick. A drop of thermal paste in the middle, then I pressed down the LED with an external device to have the hands free for soldering. The clearance of the legs ensures that the base of the led will sit flush without a gap. I soldered both legs, removed the "pressing down" device, and now its perfect. I think that the original LEDs would work much better if some bothered about the thermal paste during production.