INMP522
ALTERNATIVE PCB LAND PATTERNS
The standard PCB land pattern of the INMP522 has a solid rectangle around the edge of the footprint (see Figure 14). In some board
designs, this rectangle can make routing the microphone signals more difficult. The rectangle is used to improve the RF immunity
performance of the INMP522; however, it is not necessary to have the full rectangle connected for electrical functionality. If a design
can tolerate reduced RF immunity, this rectangle can either be broken or removed completely from the PCB footprint.
Figure 16 shows an example PCB land pattern with no enclosing rectangle around the edge of the part.
Figure 16. Example PCB Land Pattern with No Enclosing Rectangle
Figure 17 shows an example PCB land pattern with the rectangle broken on two sides so that the inner pads can be more easily
routed on the PCB.
Figure 17. Example PCB Land Pattern with Broken Enclosing Rectangle
Note that in both of these patterns, the solid ring around the sound port is still present; this ring is needed to ground the microphone
and for acoustic performance. The pad on the package connected to this ring is ground and still needs a solid electrical connection to
the PCB ground.
If a land pattern similar to Figure 16 or Figure 17 is used on a PCB, make sure that the unconnected rectangle on the bottom of the
INMP522 is not placed directly over any exposed copper. The rectangle on the microphone is still at ground, and any PCB traces
routed beneath it must be properly masked to avoid short circuits.
PCB MATERIAL AND THICKNESS
The performance of the INMP522 is not affected by PCB thickness. The INMP522 can be mounted on either a rigid or flexible PCB. A
flexible PCB with the microphone can be attached directly to the device housing with an adhesive layer. This mounting method
offers a reliable seal around the sound port, while providing the shortest acoustic path for good sound quality.
Page 17 of 21
Document Number: DS-INMP522-00
Revision: 1.1
Rev Date: 02/06/2014
