LED signs and large LED video panels are always subjected to harsh environment resulting to corrosion to their pcb mountings, here’s an app note from OSRAM about potting these LED panels for protection. Link here (PDF)
This note provides basic information about the potting of flat SMT LEDs in video wall and signage applications. Thereby details on material in use, examples of suitable equipment and the process are presented and described. Additionally, the note gives a short intro into video walls with a typical setup, varying LED type system effects and general challenges. Finally, the results of selected environmental tests are presented, to demonstrate their impact and the aptitude of potting protection method.
Potting, uggggh. Not many happy memories of potting in consumer electronics. I disassembled a dead Tesco LED 9W bulb recently and everything below the LED heat sink disk was potted in a kind of white silicone, clay- or chalk-like.
Cheaper LED bulb are beginning to like a completely smooth plastic construction _too_much_. No more cooling fins for you, no siree! Apparently (and not surprisingly) they are happy to let the LEDs stew on the heat sink slug at elevated temperatures, along with the potted buck converter IC (BP2832A apparently).
Is it any wonder that the claims of 25,000 to 30,000 hours is meaningless horse manure? Manufactured at a certain price point to last for a certain time… *sigh* Just think for a moment: Rubbish dumps will be filled with LED bulbs that have >90% working components!
simple, just put “up to 30,000 hrs” and footnote it to say the LED itself only under ideal conditions….
I can’t imagine the efficiency claims are any different, especially if they are allowed a margin of error of +/-10% or more in “testing”…..
Yeah, legally and tactically I’m sure they got themselves covered. Sucks for us consumers.
Tesco’s house brand is a hoot. On one side of the box they say “Average lifespan” and quote 30,000 hours. On another side they quote 30,000 hours* and the asterisk says “Based on average usage of 5 hours per day”. That’s 6,000 days, or hmmm, 16 years… okayyyy… the copy editor must have been smoking weed.
Maybe no OEM understands how to calculate failure rates. Or they are writing such rubbish because in China and many other countries, there is no comprehensive testing to validate claims, and business interests trumps consumer interests. And the procurers are often ****** useless.
Maybe expensive Philips or Osram work. But I think commodity LED bulbs are failing consumers. LED dies are usually 300umx300um, the thermal stresses are significant, unlike large CFL filaments. Any mismatch will hammer the weakest die. Sometimes I wish I could derate the buck converter…
Perhaps sooner or later there will be backlash and it will blow up in the manufacturers’ faces.