MinSpace S
T TraceWidth
MetalDiameter
SeeDimension
or
A
C
X Pitch
Y Pitch
SBOS468A – JUNE 2009 – REVISED JULY 2009.............................................................................................................................................................. www.ti.com
(1) Circuit traces from the NSMD-defined PWB lands should be 75-
m to 100-m wide in the exposed area inside the solder mask opening.
Wider trace widths reduce device stand-off and impact reliability.
(2) Best reliability results are achieved when the PWB laminate glass transition temperature is greater than the operating temperature range
of the intended application.
(3) For a PWB using a Ni/Au surface-finish, the Au thickness should be less than 0.5
m to avoid a reduction in thermal fatigue performance.
(4) Solder mask thickness should be less than 20
m above the copper circuit pattern.
(5) Best solder stencil performance is achieved using laser-cut stencils with electro-polishing. Use of chemically-etched stencils results in
inferior solder-paste volume control.
(6) Trace routing away from the MicrostarCSP device should be balanced in X and Y directions to avoid unintentional component movement
because of solder wetting forces.
Figure 54. Trace Width/Spacing Example
(S or T) TRACE
PAD
PACKAGE PITCH
(A or C) METAL DIAMETER
WIDTH/SPACING
NSMD
0.50 mm
0.25 mm
0.08 mm
24
Copyright 2009, Texas Instruments Incorporated