N_Cook said:
0.05
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
