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MPU9150 Datasheet PDF : 50 Pages
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MPU-9150 Product Specification
Document Number: PS-MPU-9150A-00
Revision: 4.3
Release Date: 9/18/2013
11.4 Assembly Precautions
11.4.1 Surface Mount Guidelines
InvenSense MEMS motion sensors are sensitive to mechanical stress coming from the printed circuit board
(PCB). This PCB stress can be minimized by adhering to certain design rules.
When using MEMS components in plastic packages, PCB mounting and assembly can cause package
stress. This package stress in turn can affect the output offset and its value over a wide range of
temperatures. This stress is caused by the mismatch between the Coefficient of Linear Thermal Expansion
(CTE) of the package material and the PCB. Care must be taken to avoid package stress due to mounting.
Traces connected to pads should be as symmetric as possible. Maximizing symmetry and balance for pad
connection will help component self alignment and will lead to better control of solder paste reduction after
reflow.
Any material used in the surface mount assembly process of the MEMS product should be free of restricted
RoHS elements or compounds. Pb-free solders should be used for assembly.
11.4.2 Exposed Die Pad Precautions
The MPU-9150 has very low active and standby current consumption. The exposed center die pad is not
required for heat sinking, and should not be soldered to the PCB. Under-fill should also not be used. Failure
to adhere to this rule can induce performance changes due to package thermo-mechanical stress. There is
no electrical connection between the pad and the CMOS.
11.4.3 Trace Routing
Routing traces or vias under the gyro package such that they run under the exposed die pad is prohibited.
Routed active signals may harmonically couple with the gyro MEMS devices, compromising gyro response.
These devices are designed with the drive frequencies as follows: X = 33±3kHz, Y = 30±3kHz, and
Z=27±3kHz. To avoid harmonic coupling don’t route active signals in non-shielded signal planes directly
below, or above the gyro package. Note: For best performance, design a ground plane under the e-pad to
reduce PCB signal noise from the board on which the gyro device is mounted. If the gyro device is stacked
under an adjacent PCB board, design a ground plane directly above the gyro device to shield active signals
from the adjacent PCB board.
11.4.4 Component Placement
Do not place large insertion components such as keyboard or similar buttons, connectors, or shielding boxes
at a distance of less than 6 mm from the MEMS gyro. Maintain generally accepted industry design practices
for component placement near the MPU-9150 to prevent noise coupling and thermo-mechanical stress.
11.4.5 PCB Mounting and Cross-Axis Sensitivity
Orientation errors of the gyroscope and accelerometer mounted to the printed circuit board can cause cross-
axis sensitivity in which one gyro or accel responds to rotation or acceleration about another axis,
respectively. For example, the X-axis gyroscope may respond to rotation about the Y or Z axes. The
orientation mounting errors are illustrated in the figure below.
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