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Technology Stocks : Advanced Micro Devices - Moderated (AMD) -- Ignore unavailable to you. Want to Upgrade?

To: Bill Jackson who wrote (78012)	4/23/2002 11:03:48 AM
From: Mani1	Read Replies (1) \| Respond to of 275872

Bill, good explanation. But I disagree with this point "These two replace the fragile direct to die heat sink and is a lower thermal R path than the direct to die one. " I think the sum of the two is higher than the direct attach, if the direct attach is done correctly. The problem is that since many AMD chips are assembled at DIY shops, attach is often done incorrectly. Thus causing bad thermal path, or breaking the die. Mani

To: Bill Jackson who wrote (78012)	4/23/2002 11:59:38 AM
From: tcmay	Read Replies (1) \| Respond to of 275872

">>Yes, larger contact area is not really an advantage. Because you are effectively adding a new resister in your thermal circuit.>> "I think you are replacing the initial gradient from die to the traditional heat sink through thermal compound with a lower thermal resistance to the header(copper?). This gradient will be less steep, less delta T at the interface, and thus the spreader will be able to remove more heat than the heat sink to die method. Of course you then need a heat sink to the spreader." The main effect of a heat spreader is, not surprisingly, as a _spreader_. Sounds self-evident, but it bears repeating. Look at the pictures of several configurations using heat spreaders (aka IHS) and slugs and it's clear that the heat spreaders are being used to either increase overall surface area (like the metal plate on the wooden bench example I gave a few minutes ago) or to "shunt" (conduct) the heat flow over to where conduction paths to the outside world exist. Mani's paragraph above, that " larger contact area is not really an advantage. Because you are effectively adding a new resister in your thermal circuit.", is quite clearly wrong. In the metal plate on wooden bench example, "a larger metal plate area is not really an advantage, because you are effectively adding a new resistor in your thermal circuit" is the translation. This is clearly wrong. Increasing the surface area helps, and is the whole point. Same thing with electrical grounds. --Tim May