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July 2014

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Subject:
From:
Wayne Thayer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wayne Thayer <[log in to unmask]>
Date:
Thu, 17 Jul 2014 17:13:12 +0000
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I believe UCSB is working on microfluidic heat pipes and has had some
success. But from university to practicality is a long journey! CIC cores
will be with us for many years. 

Are you trying to just spread, or do you have somewhere for this heat to go?

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Yuan-chia Joyce Koo
Sent: Thursday, July 17, 2014 11:25 AM
To: [log in to unmask]
Subject: Re: [TN] LIst of thermal conduction effective design

thanks bob and wayne.  I am more intend to looking for next gen tech, such
as phase transition material build in core of the PWB.  with high density
and super hot chip down to the road with compound semi, something need to be
addressed on the thermal side.  Yes, I am fully aware of the FEM power,
however, the limitation still in  the thermal  conduction - BN and diamond
coating are still pricy and not compatible to many of the HDI cct.  Just try
to see if there is any new trick out there.  Thanks again.
Best regards,
           joyce
On Jul 17, 2014, at 9:40 AM, Bob Landman wrote:

> Hi Joyce,
>
> Well, even PC's these days esp. with very powerful processors) use 
> heat pipes.  Of course they also use huge fans.  (warning! Pun
> ahead!!)
>
> What's really cool about heat pipes is they spread the heat and 
> conduct it to the exterior of the enclosure where there can be a 
> radiator.  My Apple MacBook Air gets so hot I can't rest it on my lap!  
> The aluminum case spreads the heat.  There is a tiny fan inside but 
> the fan's vents are under the laptop so if you do place it on your 
> lap, or when it bed reading, on a pillow, the vents are blocked. 
> Haven't had it crash on me "yet".  Why they didn't put the vents on 
> the sides? Esthetics, I'll bet, knowing Steve Jobs.
>
> E,g, http://www.thermacore.com/industries/communications.aspx    
> http://www.aavid.com/product-group/microprocessors/notebook
>
> They offer design assistance.
>
> Bob
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
> Sent: Thursday, July 17, 2014 9:20 AM
> To: [log in to unmask]
> Subject: Re: [TN] LIst of thermal conduction effective design
>
> Hi Joyce-
>
> Basically, you have to model the bejeesus out of the arrangement.  
> Nowadays that modeling is CFD (Computational Fluid Dynamics). Big 
> finite element model. And you really need a physical model in addition 
> to make sure all of the fudge factors are properly calculated. Then, 
> after you begin production, you will find your customer changed 
> something in the environment which rendered most of the modeling moot! 
> Getting good representations for actual airflow in the application can 
> be difficult to do also.
>
> If you are longer on time and short on money, a bunch of physical 
> models can also get you there, but if you are going to be playing with 
> the number of copper planes in the pcb that can get expensive too. 
> Used to be that someone, like a university, would run a bunch of those 
> kinds of modeling tests and publish results so you could interpolate 
> for your problem, but not any more: the math models have taken over.
>
> Wayne
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Yuan-chia Joyce 
> Koo
> Sent: Thursday, July 17, 2014 6:34 AM
> To: [log in to unmask]
> Subject: [TN] LIst of thermal conduction effective design
>
> Gurus,
> The most challenge in my short career of 24 years is application of 
> thermal
> components:  the requirements just go up non stop.  How do you handle 
> the thermal load in terms of static,  dynamic or transient thermal 
> load on high density PWB/PWA, besides known build in heat sink.  I am 
> seeking for the low provide conduction type, with limited or no 
> convection cooling.  Many thanks.
> (IBM's metal backing PWB is nice, but for multi-layer, >8 is a bit 
> difficult. Besides, double side or high density might have some 
> limitation - any new development in the field? ) Thanks in advance.
> (net a bit quiet, I guess many on summer vacation mode with BBQ  ;-).
>              joyce
>
>
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