and why?
I recently saw some printed advertising copy, including this statement
concerning BGA chips
"We safely remove the existing lead-free solder balls and replace them with
SnPb "

cannot find reference to that on their site, just
http://www.retronix.com/Bga_reballing
BGA Reballing (Lead Free / 63-37 / High Melt Ceramic Packages)
$1/2 million investment in a unique technology has allowed Retronix to
reball BGA and uBGA devices without inducing a thermal cycle (mass reflow),
which can damage the integrity of the device. We use a laser energy pulse
which attaches the solder spheres individually to the pad in less than
20m/s. The bonding of the sphere to pad in this short time does not allow
heat dissipation into the silicon die, therefore offering a safe alternative
to mass reflow. The equipment shown is contained within a clean room
environment, supplemented by laminar flow hoods and a nitrogen chamber for
the reballing process. We can process sphere sizes from 760 microns down to
100 microns.

On Thu, 17 Sep 2009 13:57:50 +0100, "N_Cook"
wrote:

and why?
I recently saw some printed advertising copy, including this statement
concerning BGA chips
"We safely remove the existing lead-free solder balls and replace them with
SnPb "

...


Why? Maybe you don't like the total lack of reliability of lead free
balls, perhaps?

PeterD wrote in message
...
On Thu, 17 Sep 2009 13:57:50 +0100, "N_Cook"
wrote:

and why?
I recently saw some printed advertising copy, including this statement
concerning BGA chips
"We safely remove the existing lead-free solder balls and replace them
with
SnPb "

...


Why? Maybe you don't like the total lack of reliability of lead free
balls, perhaps?


That was my thinking. mission-critical useages with RoHs derrogation,
defence/aero-space/medical or perhaps others who don't want to tarnish their
otherwise good name by knowingly producing defective goods.

Meat Plow wrote in message
...
On Thu, 17 Sep 2009 13:57:50 +0100, "N_Cook" wrote:

and why?
I recently saw some printed advertising copy, including this statement
concerning BGA chips
"We safely remove the existing lead-free solder balls and replace them
with
SnPb "

cannot find reference to that on their site, just
http://www.retronix.com/Bga_reballing
BGA Reballing (Lead Free / 63-37 / High Melt Ceramic Packages)
$1/2 million investment in a unique technology has allowed Retronix to
reball BGA and uBGA devices without inducing a thermal cycle (mass
reflow),
which can damage the integrity of the device. We use a laser energy pulse
which attaches the solder spheres individually to the pad in less than
20m/s. The bonding of the sphere to pad in this short time does not allow
heat dissipation into the silicon die, therefore offering a safe
alternative
to mass reflow. The equipment shown is contained within a clean room
environment, supplemented by laminar flow hoods and a nitrogen chamber
for
the reballing process. We can process sphere sizes from 760 microns down
to
100 microns.



Anyone who is concerned about tin whiskers?


I thought one of the advantages of using the BGA format was to avoid closely
spaced tin-whisker-liable interconnect pinning/traces.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

In article ,
Meat Plow wrote:

Watched a special on the telly the other night where lead free was
mentioned. Lead inhibits the growth of whiskers they say.

Anyways, seems that a satellite responsible for paging went down due
to whiskers a little while back. Supposedly caused quite the ruckus
here on Earth. And that some scientists in aerospace are very worried
about whiskers. Imagine some nuclear arms or even conventional
explosives fitted with lead free electronics and the newer military
and civilian aircraft electronics that are lead free.

I'll admit to not being as informed about lead-free as I should be, but
I'm pretty sure the U.S. military is packing lead, so to speak. I
assumed the same was true for militaries world wide.

Smitty Two wrote in message
news
In article ,
Meat Plow wrote:

Watched a special on the telly the other night where lead free was
mentioned. Lead inhibits the growth of whiskers they say.

Anyways, seems that a satellite responsible for paging went down due
to whiskers a little while back. Supposedly caused quite the ruckus
here on Earth. And that some scientists in aerospace are very worried
about whiskers. Imagine some nuclear arms or even conventional
explosives fitted with lead free electronics and the newer military
and civilian aircraft electronics that are lead free.

I'll admit to not being as informed about lead-free as I should be, but
I'm pretty sure the U.S. military is packing lead, so to speak. I
assumed the same was true for militaries world wide.



It is not just tin-whiskers/tin-pest/poor mechanical strength.
I was not aware of this side issue (due to 40 to 50 degree C extra
temperature at pcb soldering stage )
http://www.era.co.uk/news/rfa_feature_07b.asp

Cobham is a military concern - drone maker and in-flight fuelling equipt,
but I came across their page only 2 weeks ago with otherwise inexplicable
mysterious
2 faults with MLCC caps on a definitely non-military mixer-amp

Anyone aware of a www site pulling together all thse aspects? plenty out
there on adopting PbF practices but little on knocking it other than
piecemeal references


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/