The next generation COB LED? (Radical new style of bare LED chip.)

40
2



I’m not sure how I missed this. It’s possibly because it’s a secret that has been hiding underneath a phosphor loaded gel out of sight.
Could this be the answer to the bond-wire problems in the early low voltage 20-100W LED modules? It’s a new package of bare LED dice/chip that can literally be soldered onto a PCB as if it was a standard surface mount component. Just a very-very small one. It makes me wonder how they pick and place these and check the orientation before placing on the PCB. I guess the bare chip could be dabbed across some tiny contact pads to check if it emits light.
When I tested this COB (Chip On Board) array with very limited current the LEDs all glowed uniformly, even at the point they were all just barely visible. The same can’t be said for the older style low voltage module I also show in the video. It had a high number of defective LEDs exhibiting damage in the form of parallel resistance suggesting film damage. Possibly caused by the wire bonding process. When powered the older module would also extinguish whole rows of LEDs when pressure was applied to the busbars at the end of each series string.
Just for fun I tested this LED with a 470nF capacitor in series to act as an external current limiter. The power indicated by the Hopi was 3.4W and the module put out a useful amount of light without getting warm, and would probably last decades with that very low current. Could be a useful way to switch a floodlight made with one of these between normal power and a low level ambient output.

The contact block on the PCB which was clearly not bear-proof looks more like a push-in style for solid core wires. My attempt to treat it like a Wago terminal and “open the spring loaded contacts” just forced the folded contact strip apart and broke the little tab that is just a wedge that is supposed to part the sides just enough to get a wire back out again.

I wonder how reliable this new type of LED panel will be over time. It’s a foregone conclusion that the manufacturers will be pushing everything to its limits so thermal stresses may be an issue.

As with all this style of driverless, or more accurately DOB (Driver On Board) LED module there is no smoothing. So the flicker at 100/120Hz is strong. They could design a COB to take an external capacitor or externally rectified and smoothed supply if they increased the number of LEDs in series to accommodate the higher smoothed voltage while still allowing a margin to drop across the active current limiting circuitry.

I’m guessing that the new LED chips may be limited to Gallium Nitride technology at the moment, hence the use of phosphor to make the red and yellow COBs. The green ones seem to be available either with phosphor loaded gel or as bare green chips.

Note that if converting a 110V COB to 220V by swapping the links the current will still be set higher, so the parallel resistor cluster may need to be adjusted. If converting a 220V COB to 110V the current will be lower than a stock 110V COB.

If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-

This also keeps the channel independent of YouTube’s advertising algorithms allowing it to be a bit more dangerous and naughty.

Nguồn: https://freecode.com.vn/

40 COMMENTS

  1. I bet the SMT operator that does these hates his life.
    it's har to have the machine place so many, tiny LED's so close together consistently and without failures

  2. I know this is a bit late but I believe that the micro LEDs may be laser soldered as that gives greater accuracy and reduces the chance of thermal damage.

  3. i have seen setups that "smooth out" flicker wise as the units heat up, use to work in a factory where we refurbished devices with screens like that, take about 3 min to become solid and smooth…one of the eng's told me, it had to warm up, they designed them that way because it made them more durable in some applications, didnt really explain beyond that… but yeah, interesting stuff, a buddy of mine had a room that was lighted by black/blue lighting reflected up off a painting in the ceiling that…his mother did with black light paints…that just kinda look like its just a bit stained but…cant pick out details… once pot became legal she admitted shes always been a stoner and, the space based painting she did then..she was trying to make it so you couldnt see it unless you plugged in a black light, when they had a kid, once he was old enough, they gave it to him…my buddy… whos stoner mom now gets paid to do similar stuff in peoples homes… even do ones that look like one thing in normal light and something totally different in black light… all because her son posted pictrures from his new phones camera that worked amazing in those conditions… same room makes he pixel and samsung phones go full r-tard.. tried several of each…

  4. Can you get and look at the NEW NEW NEW laser chromatic beam converter lights? They are on new aftermarket and I think new market in general on cars for their headlights (not sure if just high beam or both high and low beam but I seen aftermarket high beam lights) they are also for grow lights – using one or two lasers – red and blue – with adjustable frequencies of output that hits these beam converters to make the laser light spread to flood onto plants and for cars, spread for seeing the road. I have a link I found on the grow light kind. No one is talking about these and it's said they are going to replace LED's!!! Have you heard of them?! You're the best of the best in my opinion on this stuff and I thought you would rage over this! (in a good way ha!) https://www.nature.com/articles/srep33885 More power efficient than LED's they say! Cheers!

  5. How can you tell which ones are which color temperature?
    I got 4 of these in one order and have absolutely no way to differentiate them

  6. Personally I just press the wire into the fitting without pressing on that tab, I only press the tab when I need to remove the wire.

  7. Well the best led 12v circut is three leds in serries with a resistor…with a separate driver is good preformer as mostly i use its running 18 hours a day now almost for 6 year till now other one is 24 volt circut mostly used in sign boards …they come in strip with aluminum base and produce bright light…I made in my entire house and in no of places …they are reliable than cheap led bulbs which are available in market …I get rid of all of them in my house as they tend to fail

  8. They got bad diodes or rectifier or not appropriate capacitors due to which it flickers…other than lack of heat sink the tend to fail very often but buy good quality cob leds they are lot relaible

  9. Now days these are available in RGB …white n even in IR for cctv….its space save if they are reliable…but not

  10. Ok because they are made with solder not gold wires ..after some time lines of leds fail in cob….u r fine research is very useful ….

  11. Flux and filament of cheap china made which are available on e bay is waste of money…nor the wattage or light meets description…..go for one with separate driver ….they are more reliable have a big heat sinks…

  12. I did lot of such direction the cheap one on e bay is worse reliable specially the direct 220v one only heat compound with screw works ..and if u solder them u will losses some in the cob i gets damaged with just slight hit to the cob

  13. Looking at the new construction without bond wires, I can see advantages in heat dissipation also. I should think the pads would also act as a little heat sink for the LED's.
    IT would be good to have LED's that actually last until the LED's actually become too dull to use rather than spontaneous failures due to bond wires failing.

  14. Thank you Clive for all your informative videos with none of the mad background "music" we get so much of these days!

  15. The Circuitry to the left of the LED looks almost like a Step Down Converter Based on those 1089B. The SHI80824060 looks to be a 35 Volt Regulator?

  16. Thanks so much for this. Reliability and longevity has been a problem with some of the fitments I've done; most customers expect LEDs to last decades. I have ordered a few of these to test. The current mode chip might be a LC5910S from Sanken (or a chinese copy).
    Once again, thanks.

  17. BP5609 seems to operate in a similar manner with an external mosfet, although that is designed for use with an active PFC circuit.

  18. Afaik the voltage after the rectifier is only half the mains voltage, so 72 LEDs in series is probably wrong. If it were only half of them in series (36) it had to be only 18 for 110 volts, which i think is unlikely due to the 12 LEDs in a row.
    I don't see how bad the flickering in reality is, but maybe there are even 48 LEDs in a row for 230V Without smoothing the LEDs would be inactive for quite a long time of each half wave. This would also explain the power consumption being way below the advertized 50W.

  19. Afaik the voltage after the rectifier is only half the mains voltage, so 72 LEDs in series is probably wrong. If it were only half of them in series (36) it had to be only 18 for 110 volts, which i think is unlikely due to the 12 LEDs in a row.
    I don't see how bad the flickering in reality is, but maybe there are even 48 LEDs in a row for 230V Without smoothing the LEDs would be inactive for quite a long time of each half wave. This would also explain the power consumption being way below the advertized 50W.

  20. With the board and the electronic bits being on the same board it is rendered un-usable in a flashlight reflector union

  21. So these are 33w true wattage in contrast to the stated 50w ? Ordered a bunch of these for a grow light and now I’m almost regretting my decision.

  22. Your videos are amazingly informative. You're very well spoken, posh some might say, but you have a natural comedic talent. Thanks for enhancing my hobby with LEDs and microelectronics!

  23. Is it possible to add a smoothing capacitor on DC side of the circuit? It would solve the biggest problem of these COB LEDs which is flickering.

LEAVE A REPLY

Please enter your comment!
Please enter your name here