cctalk Digest, Vol 110, Issue 49 - test-drb@ccmp.vtda.org

18 Oct 2012

cctalk-request at classiccmp.org wrote:
...
  Agree on the stereo microscope (dissection
microscope). I find that the 
 CCFL ring lights made for cars and motorcycles are cheap and give much 
 more intense and even (shadowless) light. Yes, they are almost perfect.  BUT, they
are usually too big in 
diameter.  By custom
making one with LEDs, you can fit it to be completely snug to the microscope
body and sit up against the sides of the microscope, so it is as far out 
of the
way as possible.  We got a ringlight with a new Chinese scope at work, but
it hung below the bottom of the scope and was over an inch wider than 
the scope
itself, so I replaced it with my own LED ring light.
...
  For large TQFPs, I anchor the chip body to the PCB
with a dab of clear 
 nail polish, using the microscope for accurate positioning.  Once the 
 polish has set, I proceed with the corner soldering.  I find that I can 
 get extremely good registration this way.  It's not fast, but it's 
 nearly foolproof.
    I'm doing 0.4mm pitch chips, and have excellent alignment, also, with my 
method.
Whatever works for you.

Jon