MAG3110
Sensors
24 Freescale Semiconductor, Inc.
7 PCB Guidelines
Surface mount Printed Circuit Board (PCB) layout is a critical portion of the total design. The footprint for the surface mount
packages must be the correct size to ensure proper solder connection interface between the PCB and the package. With the
correct footprint, the packages will self-align when subjected to a solder reflow process. These guidelines are for soldering and
mounting the Dual Flat No-Lead (DFN) package inertial sensors to PCBs. The purpose is to minimize the stress on the package
after board mounting. The MAG3110 digital output magnetometers use the DFN package platform. This section describes
suggested methods of soldering these devices to the PCB for consumer applications.
Please see Freescale application note AN4247,”Layout Recommendation for PCBs Using a magnetometer Sensor” for a
technical discussion on hard and soft-iron magnetic interference and general guidelines on layout and component selection
applicable to any PCB using a magnetometer sensor.
Freescale application note AN1902, “Quad Flat Pack No-Lead (QFN) Micro Dual Flat Pack No-Lead (DFN)” discusses the DFN
package used by the MAG3110, PCB design guidelines for using DFN packages and temperature profiles for reflow soldering.
7.1 Overview of Soldering Considerations
Information provided here is based on experiments executed on DFN devices. They do not represent exact conditions present
at a customer site. Hence, information herein should be used as guidance only and process and design optimizations are
recommended to develop an application specific solution. It should be noted that with the proper PCB footprint and solder stencil
designs, the package will self-align during the solder reflow process.
7.2 Halogen Content
This package is designed to be Halogen Free, exceeding most industry and customer standards. Halogen Free means that no
homogeneous material within the assembly package shall contain chlorine (Cl) in excess of 700 ppm or 0.07% weight/weight or
bromine (Br) in excess of 900 ppm or 0.09% weight/weight.
7.3 PCB Mounting Recommendations
1. The PCB land should be designed as Non Solder Mask Defined (NSMD) as shown in Figure 7.
2. No additional via pattern underneath package.
3. PCB land pad is 0.6 mm x 0.225 mm as shown in Figure 7.
4. Solder mask opening = PCB land pad edge + 0.125 mm larger all around = 0.725 mm x 1.950 mm
5. Stencil opening = PCB land pad -0.05 mm smaller all around = 0.55 mm x 0.175 mm.
6. Stencil thickness is 100 or 125 mm.
7. Do not place any components or vias 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.
8. Signal traces connected to pads are as symmetric as possible. Put dummy traces on NC pads in order to have same
length of exposed trace for all pads.
9. Use a standard pick and place process and equipment. Do not use a hand soldering process.
10. Assemble PCB when in an enclosure. Using caution, determine the position of screw down holes and any press fit. It is
important that the assembled PCB remain flat after assembly to keep electronic operation of the device optimal.
11. The PCB should be rated for the multiple lead-free reflow condition with max 260°C temperature.
12. No copper traces on top layer of PCB under the package. This will cause planarity issues with board mount. Freescale
DFN 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.
