Am i just unlucky or worldsemi ws2813 LEDs are crappy?

[hun_yeti]

I created a design with 20 ws2813 LEDs , and while programming the board, with minimal interaction of the board, i already had 3 LEDs fail, in different ways.
on one just one color failed, on the other the brightness regulation failed, one has completely disabled. I just followed the schematic on the datasheet.
Don't see anything obvious i could mess up.  at first all LEDs worked correctly, all colors, all brightness settings. The started to fail after more then 24 hours of the assembly.

The leds are supposedly genuine worldsemi products, ordered from LCSC. They where properly packed in anti static bags.



Just as i was writing this, the board running in demo mode, i observed another LED to fail, so it makes 4 so far, and that's 2 LEDs  in a row, so most of the leads don't work anymore.

[Siwastaja]

Do a Google search. Everyone's having reliability problems with these. Moisture is the most typical culprit for SMD LEDs, but the yield with these LEDs is poor even in careful, professional environment with moisture ruled out.

[ebastler]

I just followed the schematic on the datasheet.

So you did include the filtering (series resistors and 100nF capacitors) on the power supply, individually for each LED? Could you post your overall schematic?

[hun_yeti]

Attached the schematic. I just copied what was in the datasheet.

But even if i didn't add the resistor and the capacitor it should not destroy LEDs right?
The datasheet even states that it's okay to no add the resistor and capacitor.

[ebastler]

Hmm... Have you had a look at your power supply rail with a scope? (Any spikes or oscillations, maybe?)

Or are the LEDs mounted in a very confined space without airflow and heatsink? While the LEDs do not consume huge amounts of power, they can overheat if there is no sufficient convective or conductive cooling.

[Siwastaja]

The moisture indicator cards that were packaged with the LEDs - what did they say? Then, how did you solder the LEDs; profile, temp, time?

[wraper]

Moisture popcorning during reflow and most are not even genuine ws2813.

The leds are supposedly genuine worldsemi products, ordered from LCSC. They where properly packed in anti static bags.

Was it a proper moisture barrier bag with a silica gel bag inside?

[hun_yeti]

Hmm... Have you had a look at your power supply rail with a scope? (Any spikes or oscillations, maybe?)

Or are the LEDs mounted in a very confined space without airflow and heatsink? While the LEDs do not consume huge amounts of power, they can overheat if there is no sufficient convective or conductive cooling.

The supply rail looks fine, (or at least no oscillation in the sub Mhz range).
They have an ample amount of space, there is at least 10mm between the LEDs. Also, during programming, the where mostly under 20% of the maximum output. Also, the pads where designed to be relatively large, to help cool the LED.

Moisture popcorning during reflow and most are not even genuine ws2813.

Was it a proper moisture barrier bag with a silica gel bag inside?

The moisture indicator cards that were packaged with the LEDs - what did they say? Then, how did you solder the LEDs; profile, temp, time?

There where not in a moisture bag.
These where hand soldered, with my regular iron. I use the same iron at the same setting for thousands of components so i don't think the problem was there.

[wraper]

These where hand soldered, with my regular iron. I use the same iron at the same setting for thousands of components so i don't think the problem was there.

Hand soldering SMT components stresses them more compared to reflow. LEDs are among most sensitive.

[Siwastaja]

There where not in a moisture bag.

Found the issue. The supplier screw up the packaging.

[Siwastaja]

I use the same iron at the same setting for thousands of components so i don't think the problem was there.

Different components have different sensitivity, so the count doesn't matter. Many SMD LEDs are super sensitive to both moisture and proper soldering. You can do it manually, but need to be super careful and super quick. Preheating both the board and the components help.

[hun_yeti]

Fair enough, i didn't know that moisture control was so much important. I guess i would need to "dehydrate" them, on around 70c for many hours, to make sure everything is fine, right?
I already ordered a rework station yesterday, that may help, but this has genuinely never happened to me, having multiple components fail, after they are being in use for a few hours.

Come to think of it, it doesn't even look like the actual LED semiconductor have died, but the controller chip, since it's not transmitting the incoming data anymore.