Hello all,

Problem description:

Been happening on Rambus - part number tc59rm81xmb.
Ball diametter: 0.5 mm; ball pitch: 0.8 mm, ball
height: 0.4 mm. Pad size: 0.3 mm (11.5 mils)
5-10% of the time (we run huge amount of them) failure
modules came from opening soder join or no solder join
at all.  As we inspect the screen printing process (we
use 5 mils stencil - Dek screenprinting, cleaning
rate: 2 per print, cleaning cycle Wet-Vacuum/Dry), we
found un-event solder deposit.  Some pad even has very
little solder or no solder at all.

Stencil is electro-polish;  Diamond shape aperture,
13.5 mils open used trapezoid shape.

We afraid that if we open the apperture bigger, then
we may have bridging or solder ball.  If we reduce the
stencil to 4 mils to reduce the blockage or
resistance, then we may have in-efficient solder or
many other problem relating thin stencil (damage,
short-life, etc)

What would be your solution?

Thanks,

Stacy

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