CMA3000 Datasheet, PDF (9/18 Pages) VTI technologies – 3-axis accelerometer

CMA3000 Assembly Instructions
5 Printed Wiring Board (PWB) Level Guidelines
5.1 PWB layout
Two types of land patterns are generally used for surface mount packages:
1) Non-Solder Mask Defined Pads (NSMD)
2) Solder Mask Defined Pads (SMD).
NSMD pads have an opening which is larger than the pad itself, and SMD pads have a solder
mask opening that is smaller than the metal pad on PWB. NSMD is preferred since the copper
etching process has tighter process control compared to the solder mask process and less solder
mask originated defects. Symmetrical pad and trace designs on the CMA3000 component PWB
area are highly recommended as those would guarantee an optimal component performance.
Moreover, traces should not be routed beneath the CMA3000 component, but to use ground plane
instead in order to optimize immunity to noise coupled from signal lines. Recommended PWB land
pattern and dimensions for the CMA3000 component are presented in Figure 8. Reference layouts
are presented in corresponding product family specifications:
CMA3000 D0X_Product_Family_Specification_8281000 and
CMA3000-A0X_Product_Family_Specification_8282100.
Solder Pad
Non-Solder-Mask
Defined (NMSD)
Copper Pad
275 µm
(+0, -25 µm)
Solder Mask
Opening
375 µm
(+0, -25 µm)
Trace Width
100 µm
(±25 µm)
Figure 8. Recommended PWB pad layout and dimensions for CMA3000 component.
VTI Technologies Oy
www.vti.fi
PRELIMINARY
Subject to changes
TN68
9/18
Rev.09