many thanks.
On Jul 17, 2014, at 1:13 PM, Wayne Thayer wrote:

> 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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