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From: N_Cook on 17 Apr 2010 03:52
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


From: Jamie on 17 Apr 2010 22:21
N_Cook wrote:
> 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
>
>
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!


From: N_Cook on 17 Apr 2010 12:05
Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote in message
news:Lsjyn.11017$Db6.8438(a)newsfe05.iad...
> N_Cook wrote:
> > 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
> >
> >
> 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!
>
>


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"



From: Jeff Liebermann on 17 Apr 2010 12:59
On Sat, 17 Apr 2010 08:52:13 +0100, "N_Cook" <diverse(a)tcp.co.uk>
wrote:

>Removed in good order for re-use that is .

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

>No specialised tools available
>and I'm not going out to buy any for a once in a year job.

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.

>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

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(a)cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
From: N_Cook on 18 Apr 2010 05:55
N_Cook <diverse(a)tcp.co.uk> wrote in message
news:hqcma0$je1$2(a)news.eternal-september.org...
> Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote in message
> news:Lsjyn.11017$Db6.8438(a)newsfe05.iad...
> > N_Cook wrote:
> > > 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
> > >
> > >
> > 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!
> >
> >
>
>
> 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"
>
>
>

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
http://diverse.4mg.com/index.htm


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