We get LED failures during production and these cluster. Some batches have mutiple failures and some batches are fine.
Originally I thought this was due to LEDs failure at the higher solder temperatures required by lead free. We replaced the oven with a big beast over a year ago and we still get failures.
I understand s/m LEDs are prone to water absorption and then failure during reflow soldering. So this may be the cause.
Talking to suppliers we are getting all sorts of impractical advice. Like bake the leds OFF the reel for 48 hours. Or store at