M.2 SoM guide

Mechanical drawing

Dimensions are in millimeters.

Mating connector and land pattern

The mating connector is a an M.2 (NGFF) type 4, E key. Note that there are several different key configurations for the M.2, and type 4 is different than is commonly used on SSDs.

The TE Connectivity page for the TE 2199230-4 includes downloads for:

• Product drawings
• CAD symbol and footprint (via SnapEDA)
• 3D models
• Application specifications

The application specifications include:

• Solder paste specifications and reflow profile
• Insertion guidelines
• Storage specifications

Screw assembly

The M.2 SoM requires a screw to hold the SoM in place because the M.2 connector does not have integrated locks and the SoM will pop up if not attached to the base board. The screw also provides better vibration resistance than locking clips.

• This is one style of standoff.

• An alternative design uses a JAE SM3ZS067U410-NUT1-R1200 standoff. It's reflow soldered to your base board and has a threaded hole for a M2*3 screw to hold down the SoM. This may be easier to obtain.
• The screw should be connected to the ground plane on your base board.

Thumbscrew

For products in the field, a M2 or M2.5 screw is typically used to match the standoff that you have selected.

For prototyping, such as with the M.2 SoM breakout board, a thumbscrew can be used.

You can purchase a similar thumbscrew from these suppliers. The diameter will depend on the standoff you have used on your board, which is typically M2 or M2.5.

From Amazon:

• M2.5 x 4mm thumb screw
• M2.0 x 4mm thumb screw

From McMaster-Carr:

• M2.5 x 4mm Stainless Steel Flared-Collar Knurled-Head Thumb Screw
• M2.0 x 4mm Stainless Steel Flared-Collar Knurled-Head Thumb Screw

Design considerations

We strongly recommend against placing components under the SOM board because there is not enough height.

You can have traces underneath the SoM, on all board layers.

3D models

3D models of SoM modules are available in the hardware-libraries Github in the CAD folder, typically in formats including step, iges, stl, and f3d.

Vibration sensitivity

To validate the proper operation of M.2 SoM devices in conditions with vibration, a test based on EIA-364-28E, Test Condition I, was employed.

The sine sweep frequency vibration test uses a vibration table with an amplitude of 1.5mm. The frequency of vibration sweeps from 10 Hz to 55 Hz, then returns to 10 Hz. Each cycle takes 6 minutes and is repeated 4 times.

Additionally the test is repeated with the boards in X, Y, and Z orientation:

This is an operational test. By using a combination of MCU-internal pull-up resistors and an external pull-down resistor, interruptions in the connectivity through the M.2 connector can be detected:

PWM is also tested.

GPIO are tested using a combination of internal pull-up and external pull-down with an interrupt on change. This allows any interruption in the connectivity through the M.2 socket to be detected through software.

The test also includes tests of the internal QSPI flash, and communication with the cellular modem module during the vibration test.

All tests completed successfully.

M.2 SoM devices

The following are M.2 SoM device SKUs: