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Old 01-16-2020, 04:46 PM   #1
dicky96
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Default How to remove heatsinks from BGA chips?

I'm finding this a real problem.

Sometimes the heatsink can be rotated slightly left and right like it is held on with something rubbery and will come off with a small amount of effort using a pair of pliers.

But others are stuck on like the heatsink is a bonded part of the BGA.

I've been practicing on scrap boards and on occasion have ripped the BGA off the PCB with the heatsink still firmly attached.

Heating them up with the hot air station does not help at all. I did see a video of someone using dental floss to remove the heatsink. I didn't have any so I did try with some of the wire you use to separate mobile phone screens (like cheese wire) but it did not help in the slightest

So how do I reliably remove the heatsink when it is held on with that rock hard concrete stuff?

Last edited by dicky96; 01-16-2020 at 04:48 PM..
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Old 01-16-2020, 04:50 PM   #2
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Default Re: How to remove heatsinks from BGA chips?

Actually could one of the moderators please move this to the soldering/techniques forum please - I missposted it, sorry.

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Old 01-16-2020, 08:34 PM   #3
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Default Re: How to remove heatsinks from BGA chips?

it could be held with thermal epoxy(usually gray), tape or strange pink shit like gum. (thanks foxconn!)

if it's epoxy you will have problems, and the dust contains zinc oxide - so dont breath it.
if it's not then put a sharp blade between the chip and sink and just tap it in with something till it reaches the other side.

once your done, epoxy must be scraped off with a blade, the pink gum liquifies if you put white spirit on it and tape residue comes off with IPA.
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Old 01-17-2020, 02:50 AM   #4
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Default Re: How to remove heatsinks from BGA chips?

The stuff I am struggling with is white - I'll try to get some pics
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Old 01-17-2020, 04:47 AM   #5
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Default Re: How to remove heatsinks from BGA chips?

Here are a couple examples

The first is a Soundblaster X-Fi ExtremeGamer PCI card that is not detected by the PC and installing the drivers says the hardware is not present

However if I press down hard on the heatsink it will detect though it generally 'disappears' before the driver has completely installed causing the PC to crash

So I thought that would be a good one to practice on

The last pic is a MAG 250 - I have a box full of these faulty, sometimes it is the buck regulator chips fail and I fix them easily but the ones I have on one side have all the correct voltage rails but don't boot. I thought I would have a play with those as they don't owe me anythng. I can get replacement BGA chips cheap and they are not a programmable device according to the datasheet so it seems another good one to play with. Of course the fault could be something else.

Problem is I can't get the heatsinks off.
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File Type: jpg IMG_20200117_102735.jpg (332.3 KB, 21 views)
File Type: jpg IMG_20200117_102937.jpg (301.1 KB, 20 views)

Last edited by dicky96; 01-17-2020 at 04:49 AM..
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Old 01-17-2020, 06:58 AM   #6
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Default Re: How to remove heatsinks from BGA chips?

looks like thermal rubber compound - try the blade method
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Old 01-17-2020, 08:09 AM   #7
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Default Re: How to remove heatsinks from BGA chips?

It isn't rubbery it is rock hard. If I scratch at it as hard as I can with a Stanley knife I can chip little bits off. Maybe I could get a small hack saw blade down there
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Old 01-17-2020, 11:58 AM   #8
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Default Re: How to remove heatsinks from BGA chips?

sounds like ceramic epoxy.
hammering a blade into it is probably your best bet.
or using the blade to scrape it away till you get between the sink and chip - then you can pry it without stressing the board.
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Old 01-17-2020, 01:03 PM   #9
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Default Re: How to remove heatsinks from BGA chips?

u can also try acetone, sometimes it works for dissolving epoxies.
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Old 01-17-2020, 08:50 PM   #10
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Default Re: How to remove heatsinks from BGA chips?

If it's thermal epoxy, it should weaken when frozen.
Try deep-freezing, then pry apart with a sharp razor blade or knife.

Although heat doesn't weaken thermal epoxy, I've had good luck with heating GPU heat spreaders (like those used on the PS3 RSX GPU and G80 GeForce 8800 GTS/GTX) and prying them off with a sharp blade.
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Old 02-01-2020, 09:14 AM   #11
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Default Re: How to remove heatsinks from BGA chips?

Cutting molybden wire is very good .
E.g
https://www.ebay.com/itm/100M-0-10mm...n/143491704688
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Old 02-01-2020, 01:21 PM   #12
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Default Re: How to remove heatsinks from BGA chips?

Yeah I thought of trying that sort of 'cheese wire' but it doesn't touch it.

If i was trying with the right stuff that is - I'll post some pics of it

I managed to get a black cutting wheel on my dremel down in there between the top of the BGA and the heatsink and that did grind a bit of the white stuff away but the screw in the center of the cutting wheel hits the edge of the PCB so I only managed to remove a few mm worth. I would like to have gotten further in to it and then stuck a flat screwdriver blade in and twisted.

With the dremel it smelt a bit like a burning clutch, or brakes if you've been driving down a mountain.

I've put it on one side at the moment until I or someone else can come up with any
more bright ideas.
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Old 02-06-2020, 07:32 AM   #13
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Default Re: How to remove heatsinks from BGA chips?

OK so I got the heat sink off

I managed to gt the cutting disk far enough into the cement to insert a flat blad screwdriver between the heatsink and the top of the BGA chip

Then I twisted the screwdriver with some fair amount of pressure and the heat sink popped off

So that technique definitely works. You can clearly see where the cutting wheel has rubbed on the heatsink but not on the BGA chip

The cement stuff, whatever it is, is rock hard
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Old 02-06-2020, 12:12 PM   #14
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Default Re: How to remove heatsinks from BGA chips?

Quote:
Originally Posted by dicky96 View Post
OK so I got the heat sink off

I managed to gt the cutting disk far enough into the cement to insert a flat blad screwdriver between the heatsink and the top of the BGA chip

Then I twisted the screwdriver with some fair amount of pressure and the heat sink popped off

So that technique definitely works. You can clearly see where the cutting wheel has rubbed on the heatsink but not on the BGA chip

The cement stuff, whatever it is, is rock hard
Harbor Freight sells a 1.5 cutting disk for dermal tools
One note when using a cut off wheel if the screw comes loose then you are trying to cut to much at once

https://www.harborfreight.com/1-1-2-...ack-34749.html

I see that you are from Spain and that you might not be to get it from there but that is why I post the link to where the picture and information about what I was talking about
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