Why do TVs have ceramic heatsinks?

[KvnTM]

Hi!
I was always wondering why TV manufacturers use ceramic heatsinks on many boards. Even mixed ones where one chip has a white ceramic heatsink and another chip a black aluminium heatsink.

Is there some magic voodoo going on? I know that usually black anodized heatsinks can dissipate more heat. Why do they use white ceramic ??

Would be highly appreciated if someone could explain this sorcery..

[CapLeaker]

Re: Why do TVs have ceramic heatsinks?

one is conductive, while the other one is not?

[steviewonder]

Re: Why do TVs have ceramic heatsinks?

Philips is fond of this idea,and the ceramic ones tend to fall off too.

[KvnTM]

Re: Why do TVs have ceramic heatsinks?

Does ceramic have a higher thermal conductivity than aluminium ?

one is conductive, while the other one is not?

What would be the benefit from this? Heatsinks usually don't touch any live circuits.

Philips is fond of this idea,and the ceramic ones tend to fall off too.

Yes and it was probably one of their worst ideas. The contact surface isn't flat and they are way too small. The chip under it cooks itself. Same when it falls off of course. I can imagine that using thermal adhesive on a non flat surface would result in far worse chip temps compared to aluminium with proper thermal grease.

I smell planned obsolescence...

[Unspun01]

Re: Why do TVs have ceramic heatsinks?

Ceramic heat sinks can be "cast" in any shape and size similar to extruding aluminum so they are easy to manufacture and very versatile.

The space shuttle used ceramic heat spreading and heat dissipating materials on the bottom and nose of the shuttle upon re-entry to earth atmosphere. They could be red hot from a few thousand degrees, and then moments later they could be cool to the touch by human hand. Amazing tech. Certainly not installed in your TV, but illustrates how good porous ceramics can be at dissipating heat.

If you notice the ceramic heat sinks in your TV are also porous and helps to dissipate heat quite well.

The problem tends to be the poor adhesives and thermal paste they use to hold them in place and therefore they sometimes they fall off the chips.

I don't think there is anything wrong with a ceramic heatsink per-se. In fact - you would think that a porous ceramic would stay in place better than a smooth anodized finish.

Probably the manufacturer found a way to save a few dollars and a ceramic heat sink works pretty good. They accept heat quite fast and get rid of it quite fast. Specifically they are porous which helps the heat transfer. These are not the same as a hot ceramic dish that you pull from a hot hoven that stays hot for half an hour. They are quite good at getting rid of heat through passive means (ie - no fan).