ok i did a job a week or so ago and thought if i took some pics it may come in handy to anybody not experienced in ps3 reworking who may be looking to give it a go, basically i wasnt reworking this one but it was overheating even after new paste so i decided to remove both heatspreaders and paste under them too however its handy to know in case you also want to remove them for bga rework which i always prefer to do and think is the correct way as im pretty sure the bgas arent originally attached to the board with the heavy heatspreaders attached. the gpu one is pretty straightforward but i had never tried removing the cpu heatspreader before and thought maybe a lot of you hadnt and might want to see it done as its quite different. anyway here goes.
1. mask off around the bga as we need to cut through the adhesive which attaches the heatspreader to the cpu and its easy when cutting round to whack off a few small components lol
2. this is a picture of the wee cutting tool i made, basically is made from the very thin shielding metal that i pulled from the inside of an old xbox360 housing (the stuff that lines the top half). i cut it with tin snips added some tape to hold when cutting and then (this is the most important bit) filed it rounded at the cutting side and also filed it very carefully to ensure there were no rough edges particularly the bottom side which faces the bga so it doesnt scratch or cut into the chip
3. insert the cutter under the heatspreader and wiggle and push it until it cuts right in through the adhesive (i found this a lot easier if a started at a corner) then when its in carefully work it around the chip taking care not to angle it down towards the cpu itself. dont push it too far in just enough to get through the adhesive because you dont want to be scraping it along the edge of the die.
and hey presto
use something that wont damage the surface of the cpu to scrape off all the excess adhesive. i like to use an old xbox 360 cpu with the solder removed as it wont scrape the chip also using your nail is pretty handy too and if im careful i can even get away with using the removal tool.
make sure you use a piece of card under whatever you are prying it up with (see pic of what i used) and go in from the cpu side to avoid any small components on the gpu, once you have the card in and the knife just pull it up gently and the heatspreader will pop off.
for the cleaning of the 4 ram chips on the gpu and the heatspreader i use my hot air wand set at about 450 and an old xbox 360 gpu because its not metal and not as likely to damage anything by scraping also its small and easy to control. only give about 15-16 seconds of heat on each of the ram chips because you dont want to damage them and then the adhesive should scrape off, heat for as long as you want on the heatspreader as it will take longer and you wont damage it with heat, then wipe of the remains with mek or some other solvent. i like to finish off with a toothbrush to get the loose grit out from around all the components
for the cpu heatspreader i carefully run a stanley knife blade around it to lift the silicone type adhesive
and thats them clean
for reattach its just some thermal compound on each die and then mix up some arctic alumina thermal adhesive put some on the 4 ram chips on the gpu and a blob in each corner of the cpu heatspreader, whilst the alumina is perfect for the ram chips on the gpu its not a great solution for sticking down the cpu heatspreader but im on the lookout for an adhesive more like the original stuff they use on that. then basically push the heatspreaders firmly on and give them about 10 mins to establish a bond it actually takes over an hour to get to full strength but in a few minutes the bond will be strong enough for you to press on with putting the machine back together.
and thats you done. apologies for the dirty hands but hey, i was working after all, lol