Cracking Open an IBM 4381 MCM

[Chriscosmo12]

Heya all. Unsure if this is the right place to ask, but I have a 4381 (should be pictured in this post), and I have no idea how to get it open. Have seen people mentioning heating it a little and the heatsink will pop right off, others used a CNC machine to cut all the edges. I set my heatgun to 350*C and slowly heated each side where the solder is slightly visible, using tweezers and pliers to move the assembly around and try to separate it. Tried 450*C for a while, still no luck.

I don't want to end up damaging something so I stopped my attempt (which was over a week ago). I have another 4381 arriving in a few days and also would like to crack it open as well to see the dies. Thanks!

[isa-d]

the big heatsink come off easy with some heat
the white pad is soldered all around and you need more heat to detach it

[Chriscosmo12]

(Not sure if replying to the post is the only way I can reply to you, but giving it a shot)

So it would probably take more than 450*C in order to open it? Was just afraid if I got it that hot it would start desoldering the pins or other components on the bottom of the chip. I did hear about someone using a butane torch or something to open a CPU before. Will look into it and should report back in a few days when I have the second 4381, I appreciate the response and detailed picture!

[cooperalp]

solder melts before the gold legs, that's how we all separate the embedded ceramic chips from boards. keep heating, eventually the cap will loosen..

[Chriscosmo12]

Sweet, will give it a try. Thanks for the response!

[isa-d]

[Chriscosmo12]

Will borrow a torch from a friend since it should get hotter than my rework station.

[Chriscosmo12]

Got it open finally! Took a lot of work with a propane torch... but it's open and in pretty pristine condition. Thanks for the assistance! Also opened an IBM PowerPC MCM I may post on here (since I haven't found any images or documentation about it).

[CPUShack]

Nice work! and love to the the PowerPC

[rjluna2]

Nice job

[Chriscosmo12]

Cracked open another one today! Interesting how different it looks. Makes me curious if it is a lower tier model or something, even though there is a lot more exterior gold.

[DM8800er]

4381's come in two flavors... ones with gold-plated metal flanges (hinges on outside) and gold contact pads around dies, and ones with silver flanges, and silver contact pads

not sure what the difference is
or if there are sub-nomenclatures for them?

often more dies mean higher model
but some of us prefer the gold flange models, regardless of model

[DM8800er]

and, just to add to the thread, here is a cutaway model that was used as a sales piece
(IBM made cutaways for a variety of models)

[Chriscosmo12]

Oh dang, very cool to see a cutaway version! I'm actually getting yet another 4381 delivered tomorrow (silver variant). It is basically the only reasonably priced cool-looking MCM I've been able to find on eBay lately (besides lots of Power5+ in China). Can't wait to crack it open after work and see the die layout, will post it here.

[DM8800er]

here are two other cutaways I have collected over the years on eBay