Was Intel late in the FCPGA game?

[Demon-Xanth]

I had known that the K6 CPUs were FCPGA (w/ metal heat spreader) long before Intel went to the FCPGA form, but I have a dead Cyrix PR300 (6x86) and noticed that the ceramic cap had a gap around the edge, I looked under, it looked like an FCPGA, pop the cap off with a screw driver, it was an FCPGA w/ ceramic heat spreader.

Why do most people associate Intel with bringing up the FCPGA form when it seems like they were the last to get in on the game?

 

[AndyHui]

Not exactly.

The AMD K6 processors are PGA....still Pin Grid Array, but the entire processor die is not flipped over. The packaging they used is a modified ceramic PGA with an open top covered by the aluminium slug. This is in fact similar to the original Pentium Pro dual cavity packaging where the "heat spreader" is simply a massive copper slug over the two silicon dies (processor and cache).

Both the K6-x and the PPro are not really FC-PGA though. FC-PGA is really a die mounted backside up on top of the substrate and not sitting inside the ceramic packaging.

The first real flip chip implementation on Intel processors is the Slot 1 SECC2 package. The processor is mounted flipped over on an Organic Land Grid Array. This is then exposed directly to the Slot 1 SECC2 heatsink fan.

 

[Demon-Xanth]

http://mozcom.com/~ronnieg/articles/plate.html

There's better pictures somewhere, but they ARE FCPGA under that metal cap. They look exactly like the Athlon CPUs w/o the laser cuttable jumpers.

Edit: and I have a PPro (on loan to my sister, the MB and her CPU (the now disassembled 300M2) died), and have had a few K6 and K6-2s, the K6 and PPro construction techniques are NOT similar other than they have pins on the bottom The PPros feature an embedded aluminum casing while the K6s have a metal plate covering the CPU die.

 

[Demon-Xanth]

Removing the cover and the FCPGA construction is in full view

 

[pm]

The K6 is BGA/PGA - not FCPGA. The difference between BGA and flip-chip (FC) is subtle. To add to the confusion, however, some people talk about "flip-chip" BGA which is still just BGA. There are, IIRC, varying degrees of BGA too: super fine, very fine, ultra fine.

 

[Adul]

care to expand on the differences PM?

 

[pm]

I'll add more detail tonight.

 

[Demon-Xanth]

pm: don't leave us hanging man!

 

[pm]

This turned out to be much harder than I thought it would be. I thought I knew what I was talking about, but while researching I found out that I really don't.

There are two things here: the way to connect the die (the silicon chip) to the package, and the way to connect the package to the PCB or whatever you want to connect it to.

Flip-chip refers specifically to "C4 flip-chip" - which is a technique and a chemical process to connect a silicon die to a package. BGA is a package - it's uses solder bumps to connect a package to another component (like a PCB).

The Pentium III uses FCPGA - which is a packaging technology that takes a die, flips it and connects it directly to a PGA package. The K6 and Cyrix 6x86 PR300 used a form of BGA to connect the die to a BGA package and then connect this BGA package to a PGA package (since BGA in non-removeable, so once you solder it you can't remove it, and people like to upgrade).

A big differences between FC C4 and BGA is that within the BGA package there are wires that connect the die to the outside of the package whereas in C4, there are just bumps that connect the die directly to the package. In BGA you only wire to the periphery of the die (the outside edge) and so you have a limited number of wires (those that can fit on the outside edge) and these need to be routed across the die to wherever you want them to go. With C4 FC, you put bump spots all over the die and so you are no longer stuck using only the periphery, you can connect everywhere. So rather than having, say, 300 wires, you can no have thousands. With C4, the die directly contacts the heat-spreader (or the back of the heatsink). With BGA, the die is encapsulated within another package.

So, C4 is better. But it's much harder to do and it's a newer technology. It took years to get it working. The Athlons are all C4 FC, but the K6's and 6x86's were on some form of BGA (micro-BGA, etc.).

A cut-away picture of a BGA package.
A side-view picture of a microBGA and easyBGA package.
An article on Intel's FCPGA package technology.

 

[Demon-Xanth]

So basically what you're saying, is that the difference _ISN'T_ visible w/o cutting the chip from the ceramic then cutting that apart w/ a dicing saw? Because the K6 w/ the cover removed looks exactly like an Athlon in construction and the 6x86MX PR300 I have looks to be a very similar fashion w/ some type of coating, not unlike the P3s.

 

[pm]

The single biggest reason that I'm sure there's a difference is that flip-chip simply wasn't available back then. Beyond that, I haven't actually looked at them up close (and the pictures in the link aren't very clear) so I can't be certain. But I do know it's not C4.

One problem is that as near as I can tell Cyrix documentation is non-existant and AMD doesn't clarify beyond the fact that the K6 was on a 321-pin CPGA (ceramic pin grid array) package. So I don't have one to look at up close and I can't find any documentation that says what it is.

Does the back of your 6x86 really look like a FC part? You can see a bluish shiny covering that doesn't look plastic but looks like a form of ultra smooth metal? BGA should look like more of a ceramic or plastic appearance. If you've seen an Athlon or a Coppermine, does it really look identical to them?

I can't honestly say what package was used without looking at it closely myself or finding it in some official documentation somewhere, but I can't imagine that it's C4 simply due to the fact that no one aside from IBM was using C4 within that time frame.