"The Equalizer" by g_f

[N8]

Sorry, not related directly to the topic, but I wanted to point out that my P4 1.8A IHS was horribly unflat as well. It was very high in the center (which is better than being low in the center, anyway.)

This first picture was after several minutes using 30 micron Al2O3 lapping film and ethanol (about 320 grit equivalent). You can see how horribly high centered it was, because I am all the way into the copper and haven't even come close to lapping out to the edge yet.

This next picture was taken when I decided not to remove much more of the IHS material since I had taken off so much and you can see the irregularities of the IHS substructure. I don't think there was much left of the center section. At this point I was using 9 micron Al2O3 lapping film and ethanol (about 900 grit equivalent).

I then did a final polish with 1 micron Al2O3 lapping film and ethanol. I can't remember the conversion grit size, but probably is around equivalent to 2000 grit. I was going for the no TIM interface bond with the water block, but it kept galling when it would twist slightly when closing the stock Intel heatsink retention levers (I made a water block adaptor that could use the stock Intel mobo bracket). Anyway, just wanted to show that my P4 IHS was NOT flat at all.

[mfpmax]

still lap'n like the old daze

[gone_fishin]

Nice shine on that final pic N8. I went up to 1500 and didn't have to go as deep to get it flat, but after seeing that shine......I think I'll work on it some more

[Skulemate]

Not to rain on anyone's parade, but I thought that the P4 IHS was supposed to be raised in the middle... and that it flattened out with proper clamping force. :shrug:

Oh well, so long as your temperatures improved.

[gone_fishin]

The center and edges were the only thing making a little contact on mine. Application of a really thin layer of AS3 was worse than with a heavy application. This demonstrated the need for contact with the sunken portion to get better results.

[N8]

Originally posted by Skulemate
Not to rain on anyone's parade, but I thought that the P4 IHS was supposed to be raised in the middle... and that it flattened out with proper clamping force. :shrug:

Oh well, so long as your temperatures improved.

I have heard that before, but I have not seen the Intel source of that info. Has anyone seen Intel actually give this info? Don't take it personally, but I do not see how Intel would design something like that. There would have to be an air gap or something under the IHS, on top of the CPU, in order for it to flatten out while clamped. The sides would then also have to move outward to some extent to compensate for the flex, and I don't see that happening either.

[gone_fishin]

It may have been a result of the application of the IHS to the chip. Forced in place and glued, the thin center would have bulged slightly, but it may have been necessary to insure a good tim joint under the IHS, then the pad negated the bulge problem without the expense of another machining step to flatten it again. The nickel coating would have to have been done after it was flattened out on the chip also. It was probably a cost vs performance juggle. They kept the cost down and still got reliable performance.
All fun speculation but the spreader is bulged, that's a fact. We know that a thinner tim joint is better also. Kept as stock you are forced to either accept low surface area contact with a thin layer of goop, or use a heavy layer. Something to look for right away when AMD starts putting them on their chips too

[Skulemate]

Hmm... fair enough then. I was just curious... can't afford to actually buy one to see for my self, 'n all.

[bigben2k]

Nice work N8! So are you writing up an article?

There must be some kind of discoloration in your picture: the mirror finish doesn't have a copper color, in fact it looks like the original metal!

[N8]

Originally posted by bigben2k
Nice work N8! So are you writing up an article?

There must be some kind of discoloration in your picture: the mirror finish doesn't have a copper color, in fact it looks like the original metal!

Two reasons:

1. I focused on the reflected image, the digital camera I used can be put within a couple mm of the object, and focusing through the depth of the photo gets harder as you get that close.

2. A really good mirror finish is 'almost' colorless due to the reflection of light off the surface - the light reflects the images, not the surface characteristics of the metal.

Here is a copper cold plate with a 0.02 micron finish reflecting the image of the computer monitor behind it. You can see the copper coloring fairly easily on the cut (non-polished edge), but the surface is mostly reflecting the mirror image instead of the metal color of the surface.

[bigben2k]

Kewl

We'll note it as: if you have a mirror finish, then you can't see the copper color, and that it's a reflection of the quality of the lapping.

Many thanks!

[gone_fishin]

Here is another test version at an earlier stage of my block. Top sliced down and a presure chamber(forced channel flow) with directional nozzles incorporated as the focus of attention here
Comments appreciated.

My development page

[Blackeagle]

G F,

That block has lots of turbulance I'm sure and also a great deal of surface area. I also like the fact you use a plexy cap to it, eye candy is nice.

One concern however, what does it weigh?

How have your performance tests turned out? Figures?

[bigben2k]

It's all on the website. Very nice!!!

What was the progress on cross drilling holes into it?

[BillA]

g_f
sorry to hop back into the P4 sanding subject, but several of you might be interested

the IHS is the Marketing Dept.'s name for a CPU protective cap
made of thin copper, nickel plated after forming for corrosion resistance (discoloration), adhesively bonded to the package perimeter with epoxy

-> the protection is afforded by the relatively stiff perimeter which is lower than the central area and serves to limit the application of off-axis (angular) loading of the CPU

the 'IHS' is too thin to contribute significantly to lateral heat dispersion (run the calcs - Waterloo),
and is designed to deflect under the applied load from the spec hsf to a 'flat' plane

-> under the 'IHS' is a PCM insert, there is a 40°F offset due to the IHS plus PCM
(Intel is willing to take this ‘hit’ for the protection afforded by the ‘IHS’)

this info from an ex-Intel thermal engr with whom I have some dealings

now consider what the effect is of sanding 'off' that bump in the center of the IHS
-> instead of a somewhat concentrated load over the CPU area, the load is distributed and born also by the edges that were intended merely to stabilize the hsf
-> the compressive load on the PCM is significantly reduced and . . . .
stretch a bit, read up on what PCMs need to work well, temperature and . . . pressure !!

I’m sure everyone will report lower CPU temps after sanding,
because we see that which we wish to see
- no one here read the article about the DIYers who know more than Intel ?

mercy, tough crowd here

[gone_fishin]

I read about the intended deflection. I know I know, can't know more than the designers who made the darn thing. I do not believe that it goes to a flat plane. The paste residue was always heavy around the center which means it always was never achieving a flat plane (perhaps because it was not designed to be used with paste?) Clear marks made by the edges also, to the point of marking the base so definate load was at the edges, not just a balancing act. Have not noticed a detrimental effect. The pressure of the PCM, now that you brought it to my attention, bothers me. I think I will sand the edges down now that you have enlightened me Did that engineer mention anything about how many times it could be mounted before the phase change material looses function? And also is the 40F offset including the PCM of the stock HSF also (it's used there too)?

[BillA]

no, the 40°F was for the IHS plus its PCM
I too seriously doubt the entire surface deflects to a uniformly flat plane, but it doesn''t need to
a greater load in the center is benefical

PCMs deform on the first (several ?) cycle(s)
then the goal is to keep them undisturbed, a good app for an IHS PCM

bear in mind that no quantity of heat is being convected far from the CPU, because it can't get far from the CPU with the thin IHS

view the top of the IHS as a flexible copper membrane

and yet again g_f, what is the actual measurement capability ?
listen to your own words, eh ?

[gone_fishin]

I think you can tell by this pic that the edges were in contact with the center with just a little sanding on the left. Even after further sanding the same amount was removed frof the edges as in the middle. The pic on the right shows the copper exposed in the center and the edges but the plating is still on the belly and that is how I left it (good thing too). Some creative sanding by me will remove some more from the edges alone to get some central presure for the way it was designed to be. Thanks for the info BillA.

[gone_fishin]

Originally posted by Blackeagle
G F,

That block has lots of turbulance I'm sure and also a great deal of surface area. I also like the fact you use a plexy cap to it, eye candy is nice.

One concern however, what does it weigh?

How have your performance tests turned out? Figures?

The weight is not a factor, it is a lot lighter than the Spir@l block that I have.

[gone_fishin]

Originally posted by unregistered


PCMs deform on the first (several ?) cycle(s)
then the goal is to keep them undisturbed, a good app for an IHS PCM

This got me thinkin

As you can see from the lapping pic my edges were already even with the center so no more deflection was ever going to happen. This may be from this deformation of the PCM? The photo you can see is a different pattern than N8's, his is all copper exposed at the center with a little sanding. Perhaps he did his a lot sooner with less mountings than I had mine? If this is the case then all I did was thin out the IHS, expose the copper over the core and get rid of the neat etched in lettering which was hogging up some AS3.
Man I love to speculate but I have the photo to show where my thoughts are coming from and the photo from N8.

[BillA]

one would have to speculate about the P4 tolerance stack, I've no info like that

PCMs 'overheat' and then take their 'set'' on the first cycle, or several depending
in any case I would think the higher the center, the better;
for thats just where the pressure is desired

wish I could lap like N8

[Les]

Originally posted by unregistered

the 'IHS' is too thin to contribute significantly to lateral heat dispersion (run the calcs - Waterloo),

Although should ,possibly ,not be completely disregarded :
"green Diamonds" and "green squares" on "Christmas Tree" http://www.jr001b4751.pwp.blueyonder.co.uk/Catharbp.jpg or on http://www.jr001b4751.pwp.blueyonder.co.uk/Cathar14.jpg

[BillA]

Les
in your garland of many colors there is a assumption which I'm pretty sure is not valid
i.e. that the conductance across the TIM joint is uniform across the face of the IHS

this CANNOT be true
both in the 'unsanded' state as well as the 'sanded' one
- due to the IHS's flexibility and lack of support away from the CPU area, and away from the IHS's edges
- and note also that once sanded there is a thickness variation to deal with as well

this could all be modeled I guess, but not by me Thanks

[Les]

Originally posted by unregistered
Les
in your garland of many colors there is a assumption which I'm pretty sure is not valid
i.e. that the conductance across the TIM joint is uniform across the face of the IHS

this CANNOT be true
both in the 'unsanded' state as well as the 'sanded' one
- due to the IHS's flexibility and lack of support away from the CPU area, and away from the IHS's edges
- and note also that once sanded there is a thickness variation to deal with as well

this could all be modeled I guess, but not by me Thanks

Yes it is the "Uniform Flux" case.
However to illustrate that the spreading should not be automatically completely ignored the graphs may serve.
Waterloo do both "Parabolic" and "Equivalent Isothermal" for circular heat sources sources but not "rectangles with end cooling". I have no intention of pursuing.

[BillA]

no argument that there is some contribution;
but when 'large amounts' of residual goop are reported, then one has to wonder

BTW, I suspect the circular parabolic might not be so bad,
but what to use for 'r' returns us to the same point