Any hints/tips for removing a 5x5 ball grid array chip?

Removed in good order for re-use that is . No specialised tools available and I'm not going out to buy any for a once in a year job. I have a few ideas but have never had to do it in earnest before. There is about 0.05 mm clearance space between the balls under the chip and about 5 x 5mm in size. A few minor SM can be removed from the opposite face of the board, multilayer and about 1mm thick

Reply to
N_Cook
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mm

size.

Some ideas there. This is a glass? chip web cam CCD , having a go at making an "endoscope" so just a matter of freeing the CCD. Will not re-use BGA but individual wires soldered between with some sort of ground plane. I was thinking of kevlar fibres pushed under in X and Y sense formed into loops over some cotton wool pad that can be soaked in freezer spray. Mask off around the underside of the board and blast with hot air while tugging at the kevlar "strops"

Reply to
N_Cook

If you're trying to save the chip.. fab a small chimney to fit the outer edges to be used to direct the heat on the bottom side. Use a hot air gun, timer and suction cup puller on the top side..

Knowing the time it takes to heat the solder for proper removal will help for installing it later on.

For installation, I've cleaned the surface, used solder paste to tack down the chip. Put the chimney back on and heat up the under side while pushing down to reflow the joints. The paste helps in rejoining the joints of course.

I wouldn't recommend doing this on a regular bases but has worked for me when I didn't have the proper tools at hand..

Btw. I do have a home made ported hot air fixture I made to remove chips with under body legs. It blows the air on all four sides horizontal under the chip. The heater element was a little tricky!

Reply to
Jamie

Hot air soldering station. About $150 to $200.

Don't worry. You'll need it more than once. The [deleted expletive] BGA soldering is constantly failing in laptops, game machines, and video cards. I keep reading about rumors of yet another class action lawsuit over the HP DVxxxx series laptops, but haven't found anything.

Well, if you want to go cheap, get an IR thermometer to monitor the temperature, and heat the BGA top with a small propane torch, or tin can full of flaming alcohol and cotton. There are videos on YouTube that show how it's done with laptops and game consoles. My batting average for that method is about 50% success but getting better. Search for "BGA rework" or "BGA repair".

There's nothing to do on the other side of the board and no need to remove any SMD chips. Everything is done on the BGA side.

Getting the chip out is easy enough. With enough heat, the BGA chip will just lift off the board. Getting re-attached is a major project. Search YouTube for "BGA reballing". I've tried replacements, using brand new chips, with non-trashed solder balls, but using hand tools, with zero success. It really does take all the hardware in the videos to do it right.

Good luck.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Reply to
Jeff Liebermann

few

0.05

making

but

Unfortunately before demolishing the web-cam I have to use it , minus IR filter , to make a video for an elctronic engineer friend of mine. He reckons they would work as a thermal imager and I don't. So will film a ladder of // 1/3W Rs fed from an increasing voltage, monitored with DVM in video, up to the point of charring.

Anyway preliminary testing of procedure works. I could get a doubled up loop of 0.09mm wire under the CCD so more than I thought the other day. Needle threader fashion, to pull doubled up kevlar cord back through. About 0.01mm strands from optical fibre data cable, a nominal 10 to 20 strands run down with glue to make it handleable, otherwise its like trying to manipulate candy floss. Usually with SM IC removal I can tension up the strops to some point less than them breaking so it hardly needs much hot air to release the IC. But as glass encapsulation this time, will have to be less tension , compounded by having to heat from the reverse side. On further consideration, as heating is on reverse and low extraction force, probably only need to wire under for strops. Tensioner is just rubber O ring and standard elastic bands stretched over a wooden and plastic "gantry" , passed through some felt to protect when released and also trap the chip if it should shift from the strops. Mat of multiple layers of GRP woven glass mat high temp glued together , with a hole punched through, is the mask on the heated side

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

I tried ladder of 7 // from 100 to 330R and stepped up from 1V to 10V by

0.5V steps until the 100R started to smell, overheating. Video showed no observable difference to any of them
Reply to
N_Cook

Has been discussed at least once here before...

Reply to
Fester Bestertester

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