Why no thermal paste used between heatsink and LED MCPCB?

[treez]

The following mains LED lightbulb contains no thermal paste between the LED MCPCB and the main heatsink. Surely this is a serious assembly error?

You can see the lack of thermal paste from time 6:30 of the following video
https://www.youtube.com/watch?v=YLlpoZaBx-g

I mean, why have they gone to such trouble to make such an elaborately shaped heatsink, and then not bothereed to use a complete layer of thermal paste between LED MCPCB and heatsink?

 

[pinout]

Interesting. Hmmmm....
Well it could be that the blobs of compound are enough with a good heatsink. After all too much compound is worse than none.
It could be designed to work with just the flat surfaces so the compound is a bonus?
Cynically it could be that it works but the light performance degrades faster due to the higher operating temperatures and you have to buy a new bulb in 2 or 3 years and who will have the receipt to get a refund?

Thanks for showing the video, these tear downs can be interesting.

 

[treez]

i'd say thermal paste is expensive, and they've skimped on it.