Huawei MC509 Hardware Manual page 40

HUAWEI MC509 CDMA Mini PCIe Module
Hardware Guide
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 RUIM interface for ESD protection. The parasitic

capacitance of TVS on RUIM signal should be less than 10 pF.
Resistors in parallel and a 10 nF capacitor should be added on RESIN_N 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 following are the requirements of ESD
The electrostatic discharge protected area (EPA) must have an ESD floor whose

surface resistance and system resistance are greater than 1 x 10
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:
−
−
−
−
The parts of the equipment, devices, and tools that touch the ESD sensitive

components and moving parts that are close to the ESD sensitive components
must be made of ESD materials and have sound ground connection. The parts
that are not made of ESD materials must be handled with ESD treatment, such
as painting the ESD coating or ionization treatment (check that the friction voltage
is less than 100 V).
Key parts in the production equipment (parts that touch the ESD sensitive

components or parts that are within 30 cm away from the ESD sensitive
components), including the conveyor belt, conveyor chain, guide wheel, and SMT
nozzle, must all be made of ESD materials and be connected to the ground
properly (check that the friction voltage is less than 100 V).
Engineers that touch IC chips, boards, modules, and other ESD sensitive

components and assemblies must wear ESD wrist straps, ESD gloves, or ESD
finger cots properly. Engineers that sit when handling the components must all
wear ESD wrist straps.
Noticeable ESD warning signs must be attached to the packages and placement

areas of ESD sensitive components and assemblies.
Issue 03 (2014-12-26)
9
Ω.
Hard ground resistance < 4 Ω
5
1 x 10 Ω ≤ Soft ground resistance < 1 x 10
5
1 x 10 Ω ≤ ICT fixture soft ground resistance < 1 x 10
The electronic screwdriver and electronic soldering iron can be easily oxidized.
Their ground resistance must be less than 20 Ω.
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Copyright © Huawei Technologies Co., Ltd.
Electrical and Reliability Features
environment control:
9
Ω
11
Ω
4
Ω while less
9
Ω.
40