Freescale Semiconductor FRDM-FXS-MULTI 데이터 시트

Printed Circuit Board (PCB) layout and device mounting are critical to the overall
performance of the 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.

 discusses the QFN package used by the FXAS21000.

The following recommendations are meant to serve as general guidelines for realizing
an effective PCB layout. See 

• The PCB land pattern should be designed with Non-Solder Mask Defined (NSMD)

.

• On the layer that the device is soldered, there should be no trace routing or vias

underneath the device's component package.

• No components or vias should be placed at a distance less than 2 mm from the

package land area. This may cause additional package stress if it is too close to the
package land area.

• Signal traces connected to pads should be as symmetric as possible. Put dummy

traces on the NC pads in order to have same length of exposed trace for all pads.

• No copper traces should be on the top layer of the PCB under the package. This

will cause planarity issues with board mount. Freescale QFN sensors are compliant
with Restrictions on Hazardous Substances (RoHS), having 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.

Xtrinsic 3-Axis Digital Angular Rate Gyroscope, Rev1.2, 7/2014.

Freescale Semiconductor, Inc.