Intel® Pentium® 4 - Little Black Hole on top?

Hi,

having just installed my first P4, there is something I wasn't sure of.
What is that little black hole on the upper surface of the CPU?. I was
worried about getting any AS/3 into it when I was applying the thermal goo.
.. .

thanks,
--
Wayne ][
Sign on door reads: Please Do No Disturb! Pentium 4 assembly in progress!

Wayne Youngman wrote:

Hi,

having just installed my first P4, there is something I wasn't sure of.
What is that little black hole on the upper surface of the CPU?. I was
worried about getting any AS/3 into it when I was applying the thermal goo.
. .

thanks,

To let the air and potentially excess goo out when they slap the lid on the
package.

"David Maynard" wrote
To let the air and potentially excess goo out when they slap the lid on
the
package.


Hi,
you got me there? care to elaborate?
--
Wayne ][
Sign on door reads: Please Do No Disturb! Pentium 4 assembly in progress!

"Wayne Youngman" wrote in message
...
Hi,

having just installed my first P4, there is something I wasn't sure of.
What is that little black hole on the upper surface of the CPU?. I was
worried about getting any AS/3 into it when I was applying the thermal
goo.
. .

thanks,

A short way down the page:

http://tech-report.com/reviews/2001q1/pentium4/index3.x

Quixote

David Maynard wrote:
To let the air and potentially excess goo out when they
slap the lid on the package.

And to vent warp plasma?

Underneath the cap is usually quite a large splodge of material that
Intel use for both (obvious) conductivity & adhesion to stick it on.

Future caps will probably be different, using an interesting idea
where standoffs are used which ironically reduces hotspots:
o A heatspreader itself has to be well machined to contact the core
---- suffers the same touches-at-3-points as a heatsink to spreader
o Despite this you get hotspots regularly re spreader to core
o Solution is to use 4 or 9 standoffs between spreader & core
---- the standoffs have a thinner layer of adhesive than a spreader
---- gaps between the standoffs have thicker adhesive conversely

Ironically it reduces hot-spots quite considerably, beyond 9 standoffs
the benefit deteriorates rapidly as you tend towards a heatspreader.

It's a cheaper solution than another alternative to hotspots solved by
"wasting" silicon space. For example hot areas in the middle of a die
can conduct heat thro the substrate in 4 directions, those hot areas on
the edge can only conduct in 2 directions - a solution posted is to use
bare silicon (eg, 1mm) to drastically mitigate the W/mm^2 problem.
Sounds easy, but on a wafer you're wasting real-estate and so the
standoff solution might be engineered with the die thermal profile.

So in the future that heatspreader may get even more important.
--
Dorothy Bradbury

See, it's like building a ship in a bottle. First you get the CPU package,
then you assemble the transistors and conductors with tiny tweezers through
the hole. That's why going to smaller feature sizes make CPU's cheaper!

--
Phil Weldon, pweldonatmindjumpdotcom
For communication,
replace "at" with the 'at sign'
replace "mindjump" with "mindspring."
replace "dot" with "."

"Wayne Youngman" wrote in message
...
Hi,

having just installed my first P4, there is something I wasn't sure of.
What is that little black hole on the upper surface of the CPU?. I was
worried about getting any AS/3 into it when I was applying the thermal
goo.
. .

thanks,
--
Wayne ][
Sign on door reads: Please Do No Disturb! Pentium 4 assembly in
progress!

Intel puts it there to let the smoke out ;-0
--
Tally Ho!
Ed,
Maryland, USA
"Wayne Youngman" wrote in message
...
Hi,

having just installed my first P4, there is something I wasn't sure of.
What is that little black hole on the upper surface of the CPU?. I was
worried about getting any AS/3 into it when I was applying the thermal
goo.
. .

thanks,
--
Wayne ][
Sign on door reads: Please Do No Disturb! Pentium 4 assembly in
progress!

Fishface wrote:
David Maynard wrote:

To let the air and potentially excess goo out when they
slap the lid on the package.


And to vent warp plasma?

Of course. And a dern good thing too because there aren't many things worse
than warp plasma buildup under your heat spreader.