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Best way to remove a soldered in processor

T

TruePaige

Diamond Member
Hey guys, I've got a few toasted boards around here that don't have socketed processors, and instead are soldered to the board (BGA I guess is the proper term?). What is the best way to remove the processor and leave the gunk behind?

Thanks in advance to anyone who knows. 🙂
 
I assume you don't want to save the processor or board? Get a solder iron with a fine point and some flux, then desolder them.
 
Removal and reattachment of BGA chips without specialized reballing equipment is best left to those with tons of experience. The balls are tiny solder balls that must be desoldered, removed, and then new solder balls (or their rough equivalent) must be built. Here's a video:

http://www.youtube.com/watch?v=JB1InDsWCjQ&feature=fvw

If you don't really mean BGA, but, rather, chips with soldered copper leads, that's easier.
 
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"Best way to remove a soldered in processor"

Are you going to desolder simply to disassemble the board or are you doing it to affect a repair?
 
You say they're toasted? You don't care if they work or not?

Get a $10 1500W Heat gun a.k.a super hair dryer at harbor freight.

Heat up the area on the high setting, constantly moving the gun around. You should see the exposed solder become more shiny ( it's starting to melt ). Pick up the board with some pliers while applying heat and tap it on a hard surface. The components should just fall off. Clean off solder with a pencil iron and some desoldering wick.

Edit: Boards with ROHS or lead free solder will require high temperatures, older boards you can start at lower temperatures. If the PCB starts to discolor or peel, uh you've heated it a little too high.
 
The boards are toasted, I don't care if they work, but I'd like the processors off them to function, if that helps.

I am not reattaching them in new boards the same way, but instead want to use them in socketed boards. If that helps at all.



Also, thanks to the poster above (PottedMeat) for the heat gun suggestions, that has been in my mind for a few other fun tasks, but wondered if it was best for this one used in the same manner. I appreciate you telling me the basics of how to do it for this. 🙂

Two questions for you:

Think the processor will still work when I'm done? Can you explain a bit more about desoldering wick, a quick google search didn't enlighten me as easily as you probably can (if you don't mind). 🙂


Again, don't give two hoots about the boards and would be happy if 1/2 of the processors worked when I'm done. Never done this before, sounds fun (I like learning new things)
 
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RebateMonger said:
Removal and reattachment of BGA chips without specialized reballing equipment is best left to those with tons of experience. The balls are tiny solder balls that must be desoldered, removed, and then new solder balls (or their rough equivalent) must be built. Here's a video:

http://www.youtube.com/watch?v=JB1InDsWCjQ&feature=fvw

If you don't really mean BGA, but, rather, chips with soldered copper leads, that's easier.
Click to expand...

Pretty sure BGA is the way they do it, it's not just for the GPU on laptops, but the CPU as well, right?
 
Bateluer said:
I assume you don't want to save the processor or board? Get a solder iron with a fine point and some flux, then desolder them.
Click to expand...

Well, I'd like to save the processor.

I don't really grasp flux I guess, I gave it a quick search and it said it is for preparing a surface for soldering. Should I use that on it before I solder so it loosens up better? Or is it more for clean up duty (though I guess this whole thing is kind of clean up duty!).
 
Easy way to remove them is to heat up the CPU with blowtorch of hot air gun until the solder melts. Then you can just use some tweezers to remove it.

This will destroy the CPU and the board.

There are super expensive BGA rework tools available - but they are intended to save the board - not the chip.
 
Mark R said:
Easy way to remove them is to heat up the CPU with blowtorch of hot air gun until the solder melts. Then you can just use some tweezers to remove it.

This will destroy the CPU and the board.

There are super expensive BGA rework tools available - but they are intended to save the board - not the chip.
Click to expand...

Not a lot of faith for saving the CPU here! 🙂

Doesn't seem like it should be an insta-toast just removing the solder..is there a reason why that is so hard?

I've seen lots of GPU fix videos where you take a hot air gun right over the GPU to rig a rework. Just seems like the CPU should be disconnect-able with a little effort (not trying to put it back on which I thought would be the crazy hard part)
 
TruePaige said:
Think the processor will still work when I'm done? Can you explain a bit more about desoldering wick, a quick google search didn't enlighten me as easily as you probably can (if you don't mind). 🙂


Again, don't give two hoots about the boards and would be happy if 1/2 of the processors worked when I'm done. Never done this before, sounds fun (I like learning new things)
Click to expand...

Heh I really don't know if it will work again. I've used it before to carefully desolder SMD parts with leads and reuse them ( successfully ). Converting BGA parts to socket use? Never done that before.

Desoldering wick - when the parts come off they'll have globs of solder that you will need to remove. Put a section of wick on the solder then apply heat with the iron. The wick will suck up the solder, like a hot wick in candle wax.
 
PottedMeat said:
Heh I really don't know if it will work again. I've used it before to carefully desolder SMD parts with leads and reuse them ( successfully ). Converting BGA parts to socket use? Never done that before.

Desoldering wick - when the parts come off they'll have globs of solder that you will need to remove. Put a section of wick on the solder then apply heat with the iron. The wick will suck up the solder, like a hot wick in candle wax.
Click to expand...

Well, at least you got me started on my monsterous project..:X

I can get some of this: http://www.radioshack.com/product/in...ductId=2062744

I am just trying to figure out now why it wouldn't work, doesn't seem like a lot of visible leads where the processor is soldered in, just a little hold in. But it must not be too common place even for enthusiasts because I couldn't find much of anything on it.

Great, and now we're hit #2 for "solder and processors".
 
Wow..I think I get it now.

No..pins on the bottom of the processor, are there?

Well glad I found this out before I bought the equipment...:X
 
TruePaige said:
Wow..I think I get it now.

No..pins on the bottom of the processor, are there?

Well glad I found this out before I bought the equipment...:X
Click to expand...

Nope. A BGA processor comes with solder 'balls' on the bottom instead of pins/pads. The CPU is precisely aligned with the PCB, and the whole lot goes in an oven which melts the solder balls, soldering the CPU to the PCB.

When you desolder a BGA chip, you melt the balls and pull the chip off the board. The chip is now missing the solder balls that will connect it to a new board. Without the pre-loaded solder balls, the chip cannot be resoldered.

It is possible to make new solder balls - using a laser-cut stencil and solder paste. But a stencil for a non-standard package like a CPU would have to be custom made.
 
TruePaige said:
No..pins on the bottom of the processor, are there?
Click to expand...
The "leads" are small solder bumps that are often laid down on the CPU though metal masks via metal evaporation. I was involved in the transfer of this IBM technology to Motorola in the early 90's, where we used it to make PowerPC chips.

This technique is necessary for high-density chips where it's not practical to use old-style leads. The chips is then soldered to a substrate to provide pins or is attached directly to the PBC.

Wikipedia: Ball Grid Array
http://en.wikipedia.org/wiki/Ball_grid_array
 
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