"f825_677" wrote in message
...
Archimedes' Lever wrote:
On Mon, 24 Nov 2008 23:01:01 +0000, Eeyore
wrote:


Tom Del Rosso wrote:

"Eeyore" wrote in message
f825_677 wrote:
You should try a Sony 1602 or 1601 IC from one of their broadcast
mixer boards - it can take an hour if you're lucky and all day if
you're not and we have professionaly desoldering vacumme equipment
- the holes are barely larger than the pin its self every engineer
working on these things in every broadcast engineering department
complaints about these devices.. Give me a 100 pin BGA device any
day..
If you know the IC's buggered (or even of low commercial value), cut
every pin and remove them individually. Then clean the holes up. It
always wins on time and cost.
Isn't that a PGA? Hard to cut the pins.
Is it ? I was referring to pinned ICs. Use a flame thrower on a PGA
! ;-)

If it is a ceramic package, that is not far from the best way to remove
it.

I would: Heat the PCB up a couple hundred degrees F, then heat the
ceramic chip package body up with a high temp heat gun, while inverted.
A heat gun on the bottom of the board should cause a near instant reflow,
and release of the chip.


And all the other SMT devices will fall off the board as well - would
right off the board its a £1050 exchange PCB from Sony, but to buy new is
£11,600, the whole mixer at purchase was just over £300,000 its not a
cheap piece of equipment, but then a lot of broadcast kit is expensive and
needs special knowledge to be worked on.

I saw one of our junior engineers employ your method - I prefer my guys to
use time and patience over speed and probable damage.

Most electronics tool suppliers stock pencil blowlamps which would be
precise enough to desolder a decent size ceramic chip, some are sold in sets
with a variety of nozzle attachments. The spread is way more precise than a
heat gun.

For smaller chips it might be worth looking out for one of those "windproof"
lighters that uses the same design of jet as the pencil blowlamp - only
smaller.