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myv65 · 01-13-2003, 07:20 PM

Bill,

I agree pretty much with nicozeg on this one. And I'd add that if you've worked with AMD CPUs and haven't seen this happen, then there's something wrong on your end. It is roughly analogous to hardness measurement when you commonly use a small ball or diamond to dent a metal surface. You don't need much force when the area of contact is quite small. The net load need only be on the order of 20 lbf for the average pressure to be 100 psi. The area of the letters is much less than 1%, so if they are the only things to contact (initially) then the pressure is >10 ksi.

As an aside, there is also a time aspect to this. I tend to think this is due to imbalance in the fan and the minute reversing force this presents. Same thing could be said for water cooling and pulsations from the pump. I have never bothered (and never will) trying to characterize this versus TIM application, load, die size, etc.

And since your previous post just arrived after I'd written most of this, I'll add that it's my belief that laser engraving leaves a bit of a lip around the perimeter.

01-13-2003, 07:20 PM	#40
myv65 Cooling Savant Join Date: May 2002 Location: home Posts: 365	Bill, I agree pretty much with nicozeg on this one. And I'd add that if you've worked with AMD CPUs and haven't seen this happen, then there's something wrong on your end. It is roughly analogous to hardness measurement when you commonly use a small ball or diamond to dent a metal surface. You don't need much force when the area of contact is quite small. The net load need only be on the order of 20 lbf for the average pressure to be 100 psi. The area of the letters is much less than 1%, so if they are the only things to contact (initially) then the pressure is >10 ksi. As an aside, there is also a time aspect to this. I tend to think this is due to imbalance in the fan and the minute reversing force this presents. Same thing could be said for water cooling and pulsations from the pump. I have never bothered (and never will) trying to characterize this versus TIM application, load, die size, etc. And since your previous post just arrived after I'd written most of this, I'll add that it's my belief that laser engraving leaves a bit of a lip around the perimeter.