Emc And Esd Features - Huawei ME936 Hardware Manual

HUAWEI ME936 LTE M.2 Module
Hardware Guide
Item
Groups ≥ 2

5.6 EMC and ESD Features

The following are the EMC design comments:
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The following are the requirements of ESD
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Issue 03 (2017-12-11)
Test Condition
Attention should be paid to static control in the manufacture, assembly,
packaging, handling, and storage process to reduce electrostatic damage to
HUAWEI module.
RSE (Radiated Spurious Emission) may exceed the limit defined by EN301489 if
the antenna port is protected by TVS (Transient Voltage Suppressor), which is
resolved by making some adjustments on RF match circuit.
TVS should be added on the USB port for ESD protection, and the parasitic
capacitance of TVS on D+/D- signal should be less than 2 pF. Common-mode
inductor should be added in parallel on D+/D- signal.
TVS should be added on the SIM interface for ESD protection. The parasitic
capacitance of TVS on SIM signal should be less than 10 pF.
Resistors in parallel and a 10 nF capacitor should be added on RESET# and
Power_On_Off signal to avoid shaking, and the distance between the capacitor
and the related pin should be less than 100 mil.
PCB routing should be V-type rather than T-type for TVS.
An integrated ground plane is necessary for EMC design.
The electrostatic discharge protected area (EPA) must have an ESD floor whose
surface resistance and system resistance are greater than 1 x 10
Ω.
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than 1 x 10
The EPA must have a sound ground system without loose ground wires, and the
ground resistance must be less than 4 Ω.
The workbench for handling ESD sensitive components must be equipped with
common ground points, the wrist strap jack, and ESD pad. The resistance
between the jack and common ground point must be less than 4 Ω. The surface
resistance and system resistance of the ESD pad must be less than 1 x 10
The EPA must use the ESD two-circuit wrist strap, and the wrist strap must be
connected to the dedicated jack. The crocodile clip must not be connected to the
ground.
The ESD sensitive components, the processing equipment, test equipment,
tools, and devices must be connected to the ground properly. The indexes are as
follows:
Hard ground resistance < 4 Ω
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Ω ≤ Soft ground resistance < 1 x 10
5
1 x 10
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Ω ≤ ICT fixture soft ground resistance < 1 x 10
5
1 x 10
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Electrical and Reliability Features
Standard Sample
size
environment control:
Ω
9
11
Results
Ω while less
4
Ω.
9
Ω
66