Sensors

Freescale Semiconductor

23

MMA7455L

Figure 20. Incorrect PCB Top Metal Pattern Under

Package

Figure 21. Correct PCB Top Metal Pattern Under Package

Figure 22. Recommended PCB Land Pad, Solder Mask, and Signal Trace Near Package Design

Figure 23. Stencil Design Guidelines

Example of 2 layer PCB

Top metal pattern

under package area

Via structure under

LGA package w/ solder

PCB top metal layer

0.8 mm

0.5 mm

Package

PCB land pattern -

Cu: 0.9 x 0.6 mm

sq.

Signal trace near

package: 0.1mm width

and min. 0.5mm length

are recommended. Wider

trace can be continued

after these.

Wider trace

SM opening = PCB land pad + 0.1mm

= 1.0 x 0.7mm sq.

0.575m

0.625m

Stencil openings for 4

corner pads are bigger

than others, Refer to

next drawing.

Package

footprint

Signal trace near

package