Is LM3875 chip waterproof?

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Peter Daniel

Peter Daniel

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#1
I'm working on a new project, where GC chip would not be mounted to the heatsink (after reading pads thread I have some reservations about mounting the chip to piece of metal😉) but would be immersed in copper cylinder filled with water or some other fluid. My question is if this will effect the chip in a long run? I would be using an isolated version of a chip.

There are possible advantages to this approach of heat dissipation, mainly better damping and avoiding vibration pick up from the chassis. It is also more original way of building an amp, as I promised the members of AA to come up with something refreshing and original😉
 
#8
Most parts today can withstand cleaning with water..BUT...they need very often to be dried in a oven for quite some time.

Normal plastic (epoxy) absorb moister (failure eventually) so I unrecommend this! Maybe if you use some insulating fluid, oil but the idea seems not to be very good. :no:

You could make a tin box of copper, brass and then sink box down in the fluid. Make it completely fluid proof.

As answer to your question: NO part is water proof unless the datasheet tells you so.
 
#9
Peter,

Are you sure that the heat dissipation is better like that? Sounds to me that it would be worse than when mounting with pad on sink. I suspect hotspotting would be way worse. Obviously I don't know for sure, it just seems logical, to me at least, that it would be way worse.
 
#10
Kewl, a gainclone that's running on oil ;-)

Watch out though that certain countries do not get interested in your oil though! Also, watch out for excessive volumes or your amp will explode :devilr:

But now more seriously:

I think that it's risky to use oil or water on the chip. Even if the pins are not in the fluid, they will be during transport of the amp. Though what you COULD do is to make a metal box filled with oil (and closed well!) and mount the chip on top of it. The resonances of the metal will be damped by the oil and the heat of the cheap will be dissipated quick by the fluid. Though maybe the thermodynamic effects of the fluid will also cause resonances...

Fedde
 
#11
Peter, you should look at some extreme computer overclocking websites (I'll try to get you some urls)

Some guys completely watercooled theyr computer (except the HD and CDs) by putting them in some kind of dielectric oil

I thinks that this answears your question 😉
 
#15
It is just a wild idea, and I was thinking about isolating the chip completely from external vibrations. Putting it in some sort of fluid might be solution. Of course, I also don't have any idea about heat dissipation efficiency by a fluid, but there should be something out there that works well. As I said before, I would be using isolated version of a chip and I think it is possible to completely immerse it, while still isolating pins.

Would be interested to see those links, Bricolo.
 
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