Electronics > Projects, Designs, and Technical Stuff
120.000 LEDs - logistic nightmare
Poe:
Just some food for thought...
We recently stopped producing a product that had 344 LEDs. They were the neopixel type that fed serial data from one to the other. It only took one pixel for the entire string to fail.
The LED manufacturer said their infant mortality rate was less than 1 out of 1000. We found that one assembly out of five (1 LED out of 1720 LEDs) would fail during test due to a bad LED. The 30-day return rate was one assembly out of four! The 60-day rate was one out of twenty.
A different customer design uses 12k discrete LEDs. The claimed LED failure rate was better (1 out of 10k), but the customer would only tolerate two dead pixels per panel. Luckily the failure rate was much better (~1 out of 40k). Unfortunately, this still equated to extremely high rework after test and very high return rates.
james_s:
--- Quote from: Syntax Error on November 05, 2019, 09:45:58 pm ---@Milentije I just had a thought, there is an alternative and that's electroluminescent sheet.
It's EL wire in a glowing sheet. Used in applications from product stands to aircraft evacuation lighting, you can assemble the sheets into custom shapes. Colors are either native or filtered white light. This 'flat' light might be a better match to your concept? It's not a cheap technology, about 350 Euro a square meter, but how much would mounting thousands of LEDs cost? Just glancing at the specs for the inverters, the power consumption might be lower/greener too.
This supplier is located in the UK: https://elpanelandtape.co.uk/el-panel/
--- End quote ---
EL strip is nowhere near as bright as LEDs and the lifetime is quite limited, stuff I've had with EL backlights deteriorated after a few thousand hours.
Apollyon25_:
Many years ago I was involved with a company making LED video walls.
In just a 200mm square module, we had 432 PTH discrete R, G and B LEDs mounted on one side of the board, and the ~1500 SMT drive electronics parts mounted on the other.
Our first MP order was 2.5 million pieces of each colour so we talked to Nichia directly and got very good pricing. We used a local CM to assemble the PCBA's and they used glued SMT driver components and a wave soldering process.
As noted above you will probably need to specify wavelength and intensity bins for the LEDs. Because we needed to meet D65 white standard at the time, we had to individually measure and correct for brightness and colour shift, dynamically.
In another company using IR LEDs we used Osram LEDs and also had these binned. We used various mounting techniques from standard SMT on PCB/FPC, to COB and wire bonding to custom lead-frames.
Feel free to PM if you have any more specific questions.
mengfei:
if china is an option they'll be glad to ship that you
poorchava:
--- Quote from: Siwastaja on November 06, 2019, 06:05:26 am ---Assuming you are in Europe, one additional supplier would be Wurth Elektronic. AFAIK they don't have their own LED fabs, but do have their own brands of likely Chinese LEDs with quality control, and will happily deal with you directly.
Yes, definitely go to SMD. Design a module, which is one PCB and can be cascaded. Automated SMD PCB assembly in China is freaking cheap and easily available nowadays. pcbshopper.com also lists assembly houses.
With your massive installation, I can see it's easily hundreds of modules, driving unit cost down. I'm sure the cost of SMD leds and full SMD assembly will be less than the through hole LEDs alone, even without accounting for the work.
The only thing you need to do then, is design and order the PCBs, assembled, then assemble the modules together.
--- End quote ---
Allso, for WE stuff don't look at the prices on retail websites like DK or Mouser. The prices usually are 5x...10x of what they really are directly from WE. It's not some scam by distributors, but "corporate politics" and this is corroborated by WE FAEs to whom we have repeatedly ranted about this on every occasion.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version