Datasheet

Sensors
NXP Semiconductors 47
MMA8452Q
7 Printed Circuit Board Layout and Device Mounting
Printed Circuit Board (PCB) layout and device mounting are critical portions of the total design. The footprint for the surface mount
packages must be the correct size as a base for a proper solder connection between the PCB and the package. This, along with
the recommended soldering materials and techniques, will optimize assembly and minimize the stress on the package after board
mounting.
7.1 Printed circuit board layout
The following recommendations are a guide to an effective PCB layout. See Figure 14 for footprint dimensions.
1. Do not solder down exposed ad (EP) under the package to minimize board mounting stress impact to product
performance.
2. The solder mask should not cover any of the PCB landing pads, as shown in Figure 14.
3. No additional via nor metal pattern underneath package on the top of the PCB layer.
4. Do not place any components or vias within 2 mm of the package land area. This may cause additional package stress
if it is too close to the package land area.
5. Signal traces connected to pads should be as symmetric as possible. Put dummy traces on NC pads, to have same
length of exposed trace for all pads.
6. Use a standard pick and place process and equipment. Do not use a hand soldering process.
7. Customers are advised to be cautious about the proximity of screw down holes to the sensor, and the location of any
press fit to the assembled PCB when in an enclosure. It is important that the assembled PCB remain flat after
assembly to keep electronic operation of the device optimal.
8. The PCB should be rated for the multiple lead-free reflow condition with max 260 °C temperature.
9. NXP using halide-free molding compound (green) and lead-free terminations. These terminations are compatible with
tin-lead (Sn-Pb) as well as tin-silver-copper (Sn-Ag-Cu) solder paste soldering processes. Reflow profiles applicable to
those processes can be used successfully for soldering the devices.