Guy,
The B36 board is divided into four quandrants.  The SMT mounting pads in
quadrants C and D comprise two of the ten SIR test patterns on the board.
These mounting pads are interdigitated, or alternate between the applied
voltage and ground.  You are measuring the SIR between alternating pads.
The intent of these test patterns was to test for solder paste residues.
If you have a component with a blown chip inside, if there is anywhere in
the wire bonding where and even number pad and an odd number pad are
shorted, or if the die itself represents a low resistance path, then the
readings for these two test patterns will be false and often compromise
failures.  The mounting pads in quadrants A and B are not interdigitated,
so it makes no difference what you put in those quandrants.

Doug Pauls

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