N_Cook
Guest
Tue Dec 20, 2011 4:50 pm
Say 100 plus SMD IC with 8 or so glue spots under
Anyone have a successful method of using that hole in the pcb, if present. I
force in 2 of the smallest jeweller's blades but I'm not convinced they do
much, hoping there is no tracery hidden under. Then 2 wire loops under the
IC with tension over them to assist pull off. Freezer spray while letting
the hot air gun heat up - for those like me without the "proper" facilities.
Anyone make a jig clamp[ed to the board to force a plunger into the hole ?
if so how much force expressed per pin or whatever to break or at least
strain the glue bond but without mechanically pushing off IC and traces with
it
William Sommerwerck
Guest
Tue Dec 20, 2011 5:20 pm
Is there any way you can push a thin screwdriver blade under the IC, then
twist? I'd expect THAT to pop the IC loose.
N_Cook
Guest
Tue Dec 20, 2011 6:04 pm
William Sommerwerck <grizzledgeezer_at_comcast.net> wrote in message
news:jcqclk$a9u$1_at_dont-email.me...
Quote:
Is there any way you can push a thin screwdriver blade under the IC, then
twist? I'd expect THAT to pop the IC loose.
There is only about 1/3 mm of free space between rear of IC body and the
pcb. I may try putting a joggle in the stem of the blades and grind the
blades to a shallower angle and reduce the width and maybe that will be
possible.
abrsvc
Guest
Tue Dec 20, 2011 9:13 pm
On Dec 20, 12:04 pm, "N_Cook" <dive...@tcp.co.uk> wrote:
Quote:
William Sommerwerck <grizzledgee...@comcast.net> wrote in message
news:jcqclk$a9u$1_at_dont-email.me...
Is there any way you can push a thin screwdriver blade under the IC, then
twist? I'd expect THAT to pop the IC loose.
There is only about 1/3 mm of free space between rear of IC body and the
pcb. I may try putting a joggle in the stem of the blades and grind the
blades to a shallower angle and reduce the width and maybe that will be
possible.
Any physical force is likely to tear the traces. I use Chip Quik for
the pins first, then pry up the IC using a small jeweler's
screwdriver. ChipQuik releases the solder connections so that the
traces remain wihtout damage. I have done 1000s of these without any
problems, even with the high density pins.
Dan
N_Cook
Guest
Thu Dec 22, 2011 9:33 am
I've got inundated with work. I will be , sometime, taking some 1mm diameter
high carbon steel and grinding to a shallow tapering blade and then tapering
the edges a bit. Locally heating and trying to put in an elbow. Then a pair
of these could get in either side with 0.3mm gap and each turned to expand
to 1mm . I guess, would put in enough force to break some of the glue spots
at least, and not the traces
Jon Elson
Guest
Thu Dec 22, 2011 10:47 pm
N_Cook wrote:
Quote:
I've got inundated with work. I will be , sometime, taking some 1mm
diameter high carbon steel and grinding to a shallow tapering blade and
then tapering the edges a bit. Locally heating and trying to put in an
elbow. Then a pair of these could get in either side with 0.3mm gap and
each turned to expand to 1mm . I guess, would put in enough force to break
some of the glue spots at least, and not the traces
I think the component glue is easily softened at high temperatures.
I think that is by design, so during reflow, when the solder melts the
glue allows the component to be lowered fully into the solder. So, if you
were to heat the entire chip to reflow temperatures, the glue would likely
be quite soft. A hot-air desoldering rig ought to do the job perfectly.
Jon
Charles
Guest
Thu Dec 22, 2011 11:04 pm
"Jon Elson" wrote in message
news:NZ-dnZnsQZmrOW7TnZ2dnUVZ_qOdnZ2d_at_giganews.com...
N_Cook wrote:
Quote:
I've got inundated with work. I will be , sometime, taking some 1mm
diameter high carbon steel and grinding to a shallow tapering blade and
then tapering the edges a bit. Locally heating and trying to put in an
elbow. Then a pair of these could get in either side with 0.3mm gap and
each turned to expand to 1mm . I guess, would put in enough force to break
some of the glue spots at least, and not the traces
I think the component glue is easily softened at high temperatures.
I think that is by design, so during reflow, when the solder melts the
glue allows the component to be lowered fully into the solder. So, if you
were to heat the entire chip to reflow temperatures, the glue would likely
be quite soft. A hot-air desoldering rig ought to do the job perfectly.
Jon
Good post Jon. The glue melts before the solder does.
N_Cook
Guest
Fri Dec 23, 2011 9:18 am
Jon Elson <jmelson_at_wustl.edu> wrote in message
news:NZ-dnZnsQZmrOW7TnZ2dnUVZ_qOdnZ2d_at_giganews.com...
Quote:
N_Cook wrote:
I've got inundated with work. I will be , sometime, taking some 1mm
diameter high carbon steel and grinding to a shallow tapering blade and
then tapering the edges a bit. Locally heating and trying to put in an
elbow. Then a pair of these could get in either side with 0.3mm gap and
each turned to expand to 1mm . I guess, would put in enough force to
break
some of the glue spots at least, and not the traces
I think the component glue is easily softened at high temperatures.
I think that is by design, so during reflow, when the solder melts the
glue allows the component to be lowered fully into the solder. So, if you
were to heat the entire chip to reflow temperatures, the glue would likely
be quite soft. A hot-air desoldering rig ought to do the job perfectly.
Jon
I precool the IC body with freezer spray though. When I grind down the glue
spots it smells like standard epoxy
