Problems with the mma7361 (accelerometer)

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Problems with the mma7361 (accelerometer)

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jprestrepou
Contributor I

Hi. Some time ago I began to design a plate of a mma7361 accelerometer, the commercial bales that sell this sensor are quite large for the application that is to give, reason why it was decided to design one again, for this process the design provided by the datasheet, taking into account that we feed it by means of external source and therefore in this way we could save a little space in the regulation of the source. https://www.nxp.com/docs/en/data-sheet/MMA7361LC.pdf When testing the accelerometer already on the plate we find that it does not work, continuity has been verified at all points and this is correct, and we can not identify what the problem might be. Does anyone know about this accelerometer and try to help me? Thank you

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reyes
NXP TechSupport
NXP TechSupport

Hi Juan Pablo,

 

First, it is important to mention that the MMA7361 accelerometer is no longer manufactured, so I would recommend you to move your application to use the new family of analog accelerometers FXLN83xxq: https://www.nxp.com/products/sensors/motion-sensors/accelerometers-for-iot/nxp-analog-accelerometers...

 

Now, regarding your problem with the MMA7361, it could be a problem with the storage of the units, take in mind that the MMA7361 have a MSL level 3, which means that it have a floor life of 168 hours under 30degrees Celsius and 60% of relative humidity.

 

The Moisture Sensitivity Level (MSL) indicates the floor life of the component, its storage conditions, and handling precautions after the original container has been opened. The permissible time (from opening the moisture barrier bag until the final soldering process) a component can remain outside the moisture barrier bag is a measure of the sensitivity of the component to ambient humidity.

 

In many cases, moisture absorption leads to moisture concentrations in the component high enough to damage the package during the reflow process. The expansion of trapped moisture can result in interfacial separation, known as delamination, of the mold compound from the die or substrate, wire bond damage, die damage, and internal cracks. In the most severe cases, the component bulges and pops, known as the “popcorn” effect.

 

Thus it is necessary to dry moisture-sensitive components, to seal them in a moisture barrier antistatic bag with a desiccant and a moisture indicator card. The bag needs to be vacuum sealed according to IPC/JEDEC J-STD-033 and only the remove components immediately prior to assembly to the PCB.

 

You can find more detailed information about this topic in the Application note AN2265: https://www.nxp.com/docs/en/application-note/AN2265.pdf


Have a great day,
Jose

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