Tek LCD screen failure

[ChairmanOfTheBored]

That's the point. The problem already makes the scope unusable, some freeze
spray won't break it any worse.

Yes it very well may. Since freeze spray would take the parts it hits
below the dew point in nearly any place around, it will condensate water
immediately. One thing that LCD interfaces do NOT tolerate is moisture
between the contacts, and we already mentioned that it is NOT going to be
a component in a failure mode. So where exactly do you think this freeze
spray should be pointed such that it is going to fix a problem, or show
where one is at?

It won't, put simply. NORMAL finger pressure placed onto the contactors
at the LCD interface connections will do far more toward those goals than
introducing a moisture laden failure prone procedure ever will.

Freeze spray is for zapping a suspected transistor or FET with, not a
connectivity based mechanical contact issue. There is a place and time
for every fix in electronics, and freeze sprays and low voltage LCD panel
edge connections are NEVER one of them.

 

[James Sweet]

Yes it very well may. Since freeze spray would take the parts it hits
below the dew point in nearly any place around, it will condensate water
immediately. One thing that LCD interfaces do NOT tolerate is moisture
between the contacts, and we already mentioned that it is NOT going to be
a component in a failure mode. So where exactly do you think this freeze
spray should be pointed such that it is going to fix a problem, or show
where one is at?

It won't, put simply. NORMAL finger pressure placed onto the contactors
at the LCD interface connections will do far more toward those goals than
introducing a moisture laden failure prone procedure ever will.

Freeze spray is for zapping a suspected transistor or FET with, not a
connectivity based mechanical contact issue. There is a place and time
for every fix in electronics, and freeze sprays and low voltage LCD panel
edge connections are NEVER one of them.

Well poking and prodding often works as well, but I use freeze spray all the
time, have been for years and I've never had a problem with condensation but
then I don't live in a sauna. You don't need to hose down the whole thing
and turn it into a popsicle, just a quick shot here and there. It's great
for tracking down marginal capacitors, cracked solder joints, bad solder
under BGAs, bad connectors, anything where the problem is intermittant. When
a little squirt causes an immediate change in operation you know right where
to look.

 

[ChairmanOfTheBored]

Well poking and prodding often works as well, but I use freeze spray all the
time, have been for years and I've never had a problem with condensation but
then I don't live in a sauna.

Which I acknowledged for finding a failed PART. This is NOT a case of
a failed part. What part of that do you not understand?

You don't need to hose down the whole thing
and turn it into a popsicle, just a quick shot here and there.

When one is looking for a failed part. And don't get me wrong,
intermittent behavior IS a failure mode.

Using it to locate mechanical connectivity issues is ludicrous, at
best.

It's great
for tracking down marginal capacitors, cracked solder joints, bad solder
under BGAs, bad connectors, anything where the problem is intermittant.

Firing freeze spray UNDER a BGA is ridiculous behavior, at best.

When
a little squirt causes an immediate change in operation you know right where
to look.

When you fire it under a BGA, you will very likely ALWAYS see a
difference in circuit behavior. If you cannot see that fact, you have no
business being a tech, or attempting to call yourself one.

Also, ANY lab that has an RH below 30% is an ESD hazard, and an ESD
event waiting to happen... on a daily basis.

Any lab with an RH above 30%, the recommended value, BTW, WILL
condensate water on parts that have been shot with freeze spray.

It is basic physics 101, son. No sauna required. No goddamned freeze
spray required either.

 

[James Sweet]

When you fire it under a BGA, you will very likely ALWAYS see a
difference in circuit behavior. If you cannot see that fact, you have no
business being a tech, or attempting to call yourself one.

Also, ANY lab that has an RH below 30% is an ESD hazard, and an ESD
event waiting to happen... on a daily basis.

Any lab with an RH above 30%, the recommended value, BTW, WILL
condensate water on parts that have been shot with freeze spray.

It is basic physics 101, son. No sauna required. No goddamned freeze
spray required either.

Jeez what got stuck up this guy's butt? I'm not a tech, nor do I call myself
one, I'm a hobbyist doing this stuff for myself with a very good record of
fixing things others have given up on.

Removing the crossposting..

You don't spray anything *under* a BGA, just a quick shot on top does the
trick. Ludicrous it may be, but I've been using it for years and it works.
The contraction from the temperature change can cause a much more local
effect than prodding at a board with mechanical pressure, which can
sometimes distort the whole area of the board, while with the freeze spray
I'm able to narrow it down very easily. I don't care if it's the "right"
way, I just care that it works for me, and that it does. It's just one more
tool at my disposal and if it helps me solve the problem, great, if not,
well in the decade or so since I discovered it, I've yet to have it make
anything worse.

 

[Jim Yanik]

Well poking and prodding often works as well, but I use freeze spray
all the time, have been for years and I've never had a problem with
condensation but then I don't live in a sauna. You don't need to hose
down the whole thing and turn it into a popsicle, just a quick shot
here and there. It's great for tracking down marginal capacitors,
cracked solder joints, bad solder under BGAs, bad connectors, anything
where the problem is intermittant. When a little squirt causes an
immediate change in operation you know right where to look.

I prefer to squirt the spray on a Q-tip and put that on the suspect part.
I've seen people get into trouble using freeze spray directly,get led down
a false path.

 

[Jim Yanik]

You don't spray anything *under* a BGA, just a quick shot on top does
the trick.

If you have a bad solder joint under a BGA,how do you "fix" it?

 

[ChairmanOfTheBored]

I prefer to squirt the spray on a Q-tip and put that on the suspect part.
I've seen people get into trouble using freeze spray directly,get led down
a false path.

If one makes it spray slowly, one can fill a small cap with it, like a
mini dewar. vessel. Then, you can dip the Q-tip and soak away heat on
suspected parts all day long.

Still, these methods are not very good toward connectorization issues.

 

[James Sweet]

If you have a bad solder joint under a BGA,how do you "fix" it?

Generally you don't, but you know to stop screwing around looking for the
problem elsewhere.

It may be possible to fix with a heat gun as a last ditch effort, but that
really could do further damage.

 

[JW]

Generally you don't, but you know to stop screwing around looking for the
problem elsewhere.

It may be possible to fix with a heat gun as a last ditch effort, but that
really could do further damage.

I've had some success reflowing BGAs that have fractured or poor solder
joints around their perimeter using a Hako 850 and a small nozzle which
allows me to concentrate the air just where it's needed.

 

[Jim Yanik]

I've had some success reflowing BGAs that have fractured or poor
solder joints around their perimeter using a Hako 850 and a small
nozzle which allows me to concentrate the air just where it's needed.

it seems that the only reliable way would be to remove the BGA chip and
somehow put new solder balls and flux on all the PCB pads,then reinstall
the BGA and reflow using a preheat hot plate and hot air gun.
Never tried it,though.

 

[JW]

id: <[email protected]>:

[...]

it seems that the only reliable way would be to remove the BGA chip and
somehow put new solder balls and flux on all the PCB pads,then reinstall
the BGA and reflow using a preheat hot plate and hot air gun.
Never tried it,though.

I don't think I'd attempt it but:
http://www.finetech.de/enid/Rework_...eballing_and_Repair_of_BGA_Components_fo.html
I doubt it'd be economically feasible for the devices we use. When we have
a BGA that has failed solder joints and it can't be fixed with the Hako,
we send it out to have the chip replaced.