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bobo5195 · 02-27-2006, 04:01 PM

I need time to draft a response but given my limited time available to me and the issues that need to be discussed I thought I would give an interim post.

I disagree with the evaluation presented above and consider it an over simplification. I disagree that the numbers for high heat source materials can be analysed in this manner as I do not believe that the variables are independent due to the quasi 1D assumptions made and any rational assumption from that is hence flawed. Chips have variation in heat output between batches and over individual chips surfaces. Junction resistance is variable over the surface.

The question at the end about variation is open to the argument of, so what? The other values are easily changeable and quantifiable; IHS variation is luck of the draw and it has been shown that over the scales we are talking about the variation is important so disregarding is not valid.

As one engineer (believe it was Brunnel) put it and I can name a huge number that have nicked it:

“Show me someone who knows all the loads on their system to within 10% and I will show you a liar”.

02-27-2006, 04:01 PM	#21
bobo5195 Cooling Savant Join Date: Aug 2005 Location: uk Posts: 400	Re: T junction temp I need time to draft a response but given my limited time available to me and the issues that need to be discussed I thought I would give an interim post. I disagree with the evaluation presented above and consider it an over simplification. I disagree that the numbers for high heat source materials can be analysed in this manner as I do not believe that the variables are independent due to the quasi 1D assumptions made and any rational assumption from that is hence flawed. Chips have variation in heat output between batches and over individual chips surfaces. Junction resistance is variable over the surface. The question at the end about variation is open to the argument of, so what? The other values are easily changeable and quantifiable; IHS variation is luck of the draw and it has been shown that over the scales we are talking about the variation is important so disregarding is not valid. As one engineer (believe it was Brunnel) put it and I can name a huge number that have nicked it: “Show me someone who knows all the loads on their system to within 10% and I will show you a liar”.