Ublox M8 Series Quick setup guide

NEO-M8L
u-blox M8 automotive dead reckoning modules
including 3D sensors
Hardware integration manual
Abstract
This document describes the features and specifications of NEO-M8L, a high-performance
automotive dead reckoning (ADR) module with 3D sensors. The module includes the u-blox M8
concurrent GNSS engine with reception of GPS, GLONASS, BeiDou, Galileo and QZSS signals.
www.u-blox.com
UBX-16010549 - R08

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Early Production Information
Document information
Title
NEO-M8L
Subtitle
u-blox M8 automotive dead reckoning modules including 3D sensors
Document type
Hardware integration manual
Document number
UBX-16010549
Revision and date
R08
23-Jun-2020
Document status
Early Production Information
Disclosure restriction
C1-Public
Product status
Corresponding content status
In Development /
Prototype
Objective Specification
Target values. Revised and supplementary data will be published later.
Engineering Sample
Advance Information
Data based on early testing. Revised and supplementary data will be published later.
Initial Production
Early Production Information
Data from product verification. Revised and supplementary data may be published later.
Mass Production /
End of Life
Production Information
Document contains the final product specification.
This document applies to the following products:
Product name
Type number
ROM/FLASH version
PCN/IN reference
NEO-M8L
NEO-M8L-0-12
Flash FW3.01 ADR 4.11
UBX-17049965
NEO-M8L
NEO-M8L-01A-10
Flash FW3.01 ADR 4.03
N/A
NEO-M8L-04B
NEO-M8L-04B-00
Flash FW3.01 ADR 4.21
N/A
NEO-M8L-05B
NEO-M8L-05B-00
Flash FW3.01 ADR 4.31
UBX-20014805
u-blox or third parties may hold intellectual property rights in the products, names, logos and designs included in this
document. Copying, reproduction, modification or disclosure to third parties of this document or any part thereof is only
permitted with the express written permission of u-blox.
The information contained herein is provided “as is” and u-blox assumes no liability for its use. No warranty, either express or
implied, is given, including but not limited to, with respect to the accuracy, correctness, reliability and fitness for a particular
purpose of the information. This document may be revised by u-blox at any time without notice. For the most recent
documents, visit www.u-blox.com.
Copyright © u-blox AG.

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Contents
Document information................................................................................................................................2
Contents ..........................................................................................................................................................3
1Hardware description...........................................................................................................................5
1.1 Overview........................................................................................................................................................5
1.2 Configuration ............................................................................................................................................... 5
1.3 Connecting power .......................................................................................................................................5
1.3.1 VCC: Main supply voltage .................................................................................................................5
1.3.2 V_BCKP: Backup supply voltage ......................................................................................................5
1.3.3 VDD_USB: USB interface power supply ......................................................................................... 6
1.3.4 VCC_RF: Output voltage RF ............................................................................................................. 6
1.4 Interfaces...................................................................................................................................................... 6
1.4.1 UART .....................................................................................................................................................6
1.4.2 USB ........................................................................................................................................................6
1.4.3 Display Data Channel (DDC) .............................................................................................................7
1.4.4 SPI ..........................................................................................................................................................7
1.4.5 TX Ready signal ...................................................................................................................................8
1.5 I/O pins........................................................................................................................................................... 8
1.5.1 RESET_N: Reset input ....................................................................................................................... 8
1.5.2 WHEELTICK: Wheel tick input ......................................................................................................... 8
1.5.3 FWD: Forward/reverse input ............................................................................................................8
1.5.4 D_SEL: Interface select ..................................................................................................................... 9
1.5.5 LNA_EN: LNA enable..........................................................................................................................9
1.5.6 TIMEPULSE..........................................................................................................................................9
1.6 Electromagnetic interference on I/O lines .............................................................................................9
2Design..................................................................................................................................................... 10
2.1 Pin description ...........................................................................................................................................10
2.1.1 Pin name changes.............................................................................................................................10
2.2 Minimal design...........................................................................................................................................11
2.3 Layout: Footprint and paste mask ........................................................................................................11
2.4 Antenna.......................................................................................................................................................12
2.4.1 Antenna design with passive antenna .........................................................................................12
2.4.2 Active antenna design .....................................................................................................................13
3Automotive dead reckoning............................................................................................................ 14
3.1 Implementation .........................................................................................................................................14
3.2 Sensor calibration .....................................................................................................................................14
3.3 Software migration...................................................................................................................................14
4Product handling................................................................................................................................. 15
4.1 Packaging, shipping, storage and moisture preconditioning ..........................................................15
4.2 Soldering .....................................................................................................................................................15
4.3 EOS/ESD/EMI precautions......................................................................................................................19
4.4 Safety precautions ...................................................................................................................................21

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4.5 Applications with cellular modules........................................................................................................22
Appendix ....................................................................................................................................................... 24
ARecommended parts ......................................................................................................................... 24
BRecommended antennas ................................................................................................................. 25
Related documents ................................................................................................................................... 26
Revision history.......................................................................................................................................... 27
Contact.......................................................................................................................................................... 28

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1Hardware description
1.1 Overview
The NEO-M8L modules are 3D dead reckoning GNSS receivers for automotive applications using a
built-in 6-axis sensor (3-axis gyroscope and 3-axis accelerometer) and featuring the high performance
u-blox M8 concurrent positioning engine. Available in the NEO industry standard leadless chip carrier
(LCC) package, they are easy to integrate and combine exceptional positioning performance with
highly flexible power, design, and connectivity options. SMT pads allow fully automated assembly with
standard pick & place and reflow-soldering equipment for cost-efficient, high-volume production
enabling short time-to-market.
☞For more information about the product features, see the corresponding product data sheet [1],
[2], or [3] in the Related documents section.
☞To determine which u-blox product best meets your needs, see the product selector tables on the
u-blox website www.u-blox.com.
1.2 Configuration
The configuration settings can be modified using UBX protocol configuration messages (see the u-
blox 8 / u-blox M8 Receiver Description Including Protocol Specification [4]). The modified settings
remain effective until power-down or reset. If these settings have been stored in battery-backed RAM
(BBR), then the modified configuration will be retained, as long as the backup battery supply is not
interrupted.
For NEO-M8L modules, the configuration can be saved permanently in SQI flash.
1.3 Connecting power
The NEO-M8L positioning modules have up to three power supply pins: VCC, V_BCKP and VDD_USB.
1.3.1 VCC: Main supply voltage
The VCC pin provides the main supply voltage. During operation, the current drawn by the module can
vary by some orders of magnitude, especially if enabling low-power operation modes. For this reason,
it is important that the supply circuitry be able to support the peak power for a short time (see the
corresponding product data sheet in the Related documents section for the specifications).
☞When switching from backup mode to normal operation or at start-up, the NEO-M8L modules
must charge the internal capacitors in the core domain. In certain situations, this can result in a
significant current draw. For low power applications using power save and backup modes, it is
important that the power supply or low ESR capacitors at the module input can deliver this
current/charge.
☞Use a proper GND concept. Do not use any resistors or coils in the power line.
1.3.2 V_BCKP: Backup supply voltage
If the module supply has a power failure, the V_BCKP pin supplies the real-time clock (RTC) and
battery-backed RAM (BBR). Use of valid time and the GNSS orbit data at startup will improve the
GNSS performance, as with hot starts, warm starts, AssistNow Autonomous and AssistNow Offline.
If no backup battery is connected, the module performs a cold start at power up.
☞A backup supply voltage should be provided to the NEO-M8L to enable navigation by dead
reckoning before the first GNSS fix.

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☞Avoid high resistance on the V_BCKP line: During the switch from main supply to backup supply,
a short current adjustment peak can cause high voltage drop on the pin with possible
malfunctions.
☞If no backup supply voltage is available, connect the V_BCKP pin to VCC.
☞As long as power is supplied to the NEO-M8L modules through the VCC pin, the backup battery is
disconnected from the RTC and the BBR to avoid unnecessary battery drain (see Figure 1). In this
case, VCC supplies power to the RTC and BBR.
Figure 1: Backup battery and voltage (for exact pin orientation, see the corresponding product Data sheet)
1.3.3 VDD_USB: USB interface power supply
VDD_USB supplies the USB interface. If the USB interface is not used, the VDD_USB pin must be
connected to GND. For more information about correctly handling the VDD_USB pin, see section 1.4.
1.3.4 VCC_RF: Output voltage RF
The VCC_RF pin can supply an active antenna or external LNA. For more information, see section 2.4.
1.4 Interfaces
For more information about the interfaces (baud rates, bandwidth, speed and clock frequency, and so
on), see the corresponding product data sheet [1], [2], or [3] in the Related documents section.
1.4.1 UART
NEO-M8L 3D dead reckoning modules include a Universal Asynchronous Receiver Transmitter
(UART) serial interface RXD/TXD supporting configurable baud rates.
The signal output and input levels are 0 V to VCC. An interface based on RS232 standard levels (+/-
12 V) can be implemented using level shifters such as Maxim MAX3232. Hardware handshake signals
and synchronous operation are not supported.
1.4.2 USB
A USB version 2.0 FS (full speed, 12 Mb/s) compatible interface is available for communication as an
alternative to the UART. The USB_DP integrates a pull-up resistor to signal a full-speed device to the
host. The VDD_USB pin supplies the USB interface.
u-blox provides Microsoft® certified USB drivers for Windows Vista, Windows 7, Windows 8 and
Windows 10. These drivers are available at our website, www.u-blox.com.
USB external components
The USB interface requires some external components to implement the physical characteristics
required by the USB 2.0 specification. These external components are shown in Figure 2 and listed in

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Table 1. To comply with USB specifications, VBUS must be connected through an LDO (U1) to pin
VDD_USB on the module.
In USB self-powered mode, the power supply (VCC) can be turned off and the digital block is not
powered. In this case, since VBUS is still available, the USB host would still receive the signal indicating
that the device is present and ready to communicate. This should be avoided by disabling the LDO
(U1) using the enable signal (EN) of the VCC-LDO or the output of a voltage supervisor. Depending on
the characteristics of the LDO (U1), it is recommended to add a pull-down resistor (R11) at its output
to ensure VDD_USB is not floating if the LDO (U1) is disabled or the USB cable is not connected, that
is, VBUS is not supplied.
☞USB bus-powered mode is not supported.
Module
VDD_USB
LDO
VDD_USB
R4
USB_DP
USB_DM
R5
C24 C23
D2
VBUS
DP
DM
GND
USB Device Connector
U1
EN R11
EN
Figure 2: USB Interface
Name
Component
Function
Comments
U1
LDO
Regulates VBUS (4.4 …5.25 V)
down to a voltage of 3.3 V.
Almost no current requirement (~1 mA) if the GNSS receiver is
operated as a USB self-powered device.
C23,
C24
Capacitors
Required according to the specification of LDO U1.
D2
Protection diodes
Protect circuit from overvoltage /
ESD when connecting.
Use low-capacitance ESD protection such as ST
Microelectronics USBLC6-2.
R4, R5
Serial termination
resistors
Establish a full-speed driver
impedance of 28…44 
A value of 27 is recommended.
R11
Resistor
100 kis recommended for USB self-powered setup.
Table 1: Summary of USB external components
1.4.3 Display Data Channel (DDC)
An I2C-compatible Display Data Channel (DDC) interface is available with a NEO-M8L module for serial
communication with an external host CPU. The interface only supports operation in slave mode
(master mode is not supported). The DDC protocol and electrical interface are fully compatible with
the fast mode of the I2C industry standard. DDC pins SDA and SCL have internal pull-up resistors.
For more information about the DDC implementation, see the u-blox 8 / u-blox M8 Receiver
Description Including Protocol Specification [4]. For timing, parameters consult the I2C-bus
specification [9].
☞The NEO-M8L DDC interface supports serial communication with u-blox cellular modules. See the
specification of the applicable cellular module to confirm compatibility.
1.4.4 SPI
An SPI interface is available for communication to a host CPU.

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☞SPI is not available in the default configuration, because its pins are shared with the UART and
DDC interfaces. The SPI interface can be enabled by connecting D_SEL to ground. For speed and
clock frequency, see the corresponding product data sheet in the Related documents section.
1.4.5 TX Ready signal
The TX Ready signal indicates that the receiver has data to transmit. A listener can wait on the TX
Ready signal instead of polling the DDC or SPI interfaces. The UBX-CFG-PRT message lets you
configure the polarity and the number of bytes in the buffer before the TX Ready signal goes active.
The TX Ready signal can be mapped to UART TXD (PIO 06). The TX Ready function is disabled by
default.
☞The TX Ready functionality can be enabled and configured by AT commands sent to the u-blox
cellular module supporting the feature. For more information, see the GPS Implementation and
Aiding Features in u-blox wireless modules [10].
1.5 I/O pins
1.5.1 RESET_N: Reset input
Driving RESET_N low activates a hardware reset of the system. Use this pin to reset the module only.
Do not use RESET_N to turn the module on and off, since the reset state increases power
consumption. With the NEO-M8L modules the RESET_N pin is an input only.
☞Use RESET_N in critical situations only to recover the system. RESET_N also resets the real-time
clock which means that the receiver cannot perform hot start immediately after RESET_N.
1.5.2 WHEELTICK: Wheel tick input
The wheel tick input, also known as the HW interface, is used to provide speed pulse (wheel tick)
information to the NEO-M8L modules. By default the wheel tick count is based on the rising edge of
the wheel tick pulse signal. To improve performance with lower rate mechanically derived wheel-tick
signals, the receiver may be configured to use both the rising and falling edges of the wheel tick signal
on the condition that the wheel tick pulses have approximately 1:1 mark:space ratio regardless of
speed. The minimum recommended pulse width is 10 us.
The pulse interval (WT resolution) should be less than 40 cm per tick over distance travelled. For best
performance, less than 2 cm/tick is recommended. The wheel tick pulse output shall change linearly
with the change in speed (navigation filter estimates only the linear scale factor). If the vehicle is
standing still, there should be no wheel tick pulses. This is particularly important at system shut down
and power up. If there is a dead-band (wheel tick pulse does not change or is not output below a certain
speed), performance will be affected at low speed.
If the speed pulse is available from the host processor, then the information can also be provided by
SW interface using the UBX-ESF-MEAS message. In this particular case, the wheel-tick pin can be
configured as EXTINT1 and used to provide a time mark for the message. For more information, see
the u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [4].
☞Do not exceed the maximum voltage of 3.6 V at the input when using the HW interface.
1.5.3 FWD: Forward/reverse input
The forward/reverse input is used to indicate the moving direction by an external signal (HW
interface). By default the wheel-tick direction pin polarity is automatically initialized once the vehicle
has reached required minimum speed of 30 km/h. The forward/reverse input polarity can also be set
manually. If the forward/reverse information is available from the host processor, the UBX-ESF-MEAS

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message can also be used to provide the direction of motion (SW interface). For more information,
see the u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [4].
☞Do not exceed the maximum voltage of 3.6 V at the input when using the HW interface. When
using a SW interface this pin is not used and can be left open.
☞No forward or reverse input will cause incorrect operation.
1.5.4 D_SEL: Interface select
The D_SEL pin selects the available interfaces. SPI cannot be used simultaneously with the
UART/DDC. If open, UART and DDC are available. If pulled low, the SPI interface is available.
1.5.5 LNA_EN: LNA enable
In power save mode, the system can turn on/off an optional external LNA using the LNA_EN signal in
order to optimize power consumption.
1.5.6 TIMEPULSE
A configurable time pulse signal is available with the NEO-M8L modules. It generates pulse trains
synchronized with GPS or UTC time grid with intervals configurable over a wide frequency range. For
more information, see the u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification
[4].
☞The NEO-M8L time-pulse output is configured using messages for “TIMEPULSE2”.
☞The time-pulse output must not be held LOW during start-up.
1.6 Electromagnetic interference on I/O lines
Any I/O signal line with a length greater than approximately 3 mm can act as an antenna and may pick
up arbitrary RF signals transferring them as noise into the GNSS receiver. This specifically applies to
unshielded lines, in which the corresponding GND layer is remote or missing entirely, and lines close
to the edges of the printed circuit board.
If, for example, a cellular signal radiates into an unshielded high-impedance line, it is possible to
generate noise in the order of volts and not only distort receiver operation but also damage it
permanently.
On the other hand, noise generated at the I/O pins will emit from unshielded I/O lines. Receiver
performance may be degraded when this noise is coupled into the GNSS antenna (see Figure 16).
To avoid interference by improperly shielded lines, it is recommended to use resistors (for example,
R>20 ), ferrite beads (for example, BLM15HD102SN1) or inductors (for example, LQG15HS47NJ02)
on the I/O lines in series. Choose these components carefully because they also affect the signal rise
times.
Figure 3 shows an example of EMI protection measures on the RX/TX line using a ferrite bead.
Figure 3: EMI precautions
More information is available in section 4.3.
TX
RX
GNSS
Receiver
FB
FB
BLM15HD102SN1
>10mm

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2Design
2.1 Pin description
No
Name
I/O
Description
1
SAFEBOOT_N
I
SAFEBOOT_N, test-point for service use (leave OPEN)
2
D_SEL
I
Interface select
3
TIMEPULSE
I/O
Time pulse (disabled by default). Do not pull low during reset.
Note: configured using TIMEPULSE2 messages (see u-blox 8 / u-blox M8
Receiver Description Including Protocol Specification [4])
4
WHEELTICK
I
Wheel tick input
5
USB_DM
I/O
USB data
6
USB_DP
I/O
USB data
7
VDD_USB
I
USB supply
8
RESET_N
I
RESET_N
9
VCC_RF
O
Output voltage RF section
10
GND
I
Ground
11
RF_IN
I
GNSS signal input
12
GND
I
Ground
13
GND
I
Ground
14
LNA_EN
O
LNA enable
15
FWD
I
Forward/reverse input for speed pulse
16
RESERVED
-
Reserved
17
RESERVED
-
Reserved
18
SDA / SPI CS_N
I/O
DDC data if D_SEL =1 (or open) / SPI chip select if D_SEL = 0
19
SCL / SPI CLK
I/O
DDC clock if D_SEL =1(or open) / SPI clock if D_SEL = 0
20
TXD / SPI MISO
O
Serial port if D_SEL =1(or open) / SPI MISO if D_SEL = 0
21
RXD / SPI MOSI
I
Serial port if D_SEL =1(or open) / SPI MOSI if D_SEL = 0
22
V_BCKP
I
Backup voltage supply
23
VCC
I
Supply voltage
24
GND
I
Ground
Table 2: Pinout of NEO-M8L modules
2.1.1 Pin name changes
Selected pin names have been updated to agree with a common naming convention across u-blox
modules. The pins have not changed their operation and are the same physical hardware, but with
updated names. The table below lists the pins that have a changed name along with their old and new
names.
No
Previous name
New name
14
ANT_ON
LNA_EN
16
NC
RESERVED
17
NC
RESERVED
20
TxD / SPI MISO
TXD / SPI MISO
21
RxD / SPI MOSI
RXD / SPI MOSI
Table 3: Pin name changes in NEO-M8L-0 (Professional grade)

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2.2 Minimal design
This is a minimal design for a NEO-M8L GNSS receiver.
Figure 4: NEO-M8L passive antenna design
2.3 Layout: Footprint and paste mask
Figure 5 describes the footprint and provides recommendations for the paste mask for NEO-M8L
modules. These are recommendations only and not specifications. Note that the copper and solder
masks have the same size and position.
To improve the wetting of the half vias, reduce the amount of solder paste under the module and
increase the volume outside of the module by defining the dimensions of the paste mask to form a T-
shape (or equivalent) extending beyond the copper mask. For the stencil thickness, see section 4.2.
☞Consider the paste mask outline when defining the minimal distance to the next component. The
exact geometry, distances, stencil thicknesses and solder paste volumes must be adapted to the
specific production processes (e.g. soldering) of the customer.
Figure 5: NEO-M8L paste mask / footprint

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2.4 Antenna
2.4.1 Antenna design with passive antenna
A design using a passive antenna requires more attention to the layout of the RF section. Typically, a
passive antenna is located near electronic components; therefore, care should be taken to reduce
electrical noise that may interfere with the antenna performance. Passive antennas do not require a
DC bias voltage and can be directly connected to the RF input pin RF_IN. Sometimes, they may also
need a passive matching network to match the impedance to 50 .
Figure 6 shows a minimal setup for a design with a good GNSS patch antenna. For exact pin
orientation, see the Appendix and the corresponding product Data sheet [1], [2], or [3] in the Related
documents section.
Figure 6: Module design with passive antenna
☞Use an antenna that has sufficient bandwidth to receive all GNSS constellations. For more
information, see and the GPS Antenna Application Note [6].
Figure 7 shows a design using an external LNA and SAW to increase the sensitivity for best
performance with passive antenna.
Figure 7: Module design with passive antenna and an external LNA and SAW
The LNA_EN pin (LNA enable) can be used to turn an optional external LNA on and off.
The VCC_RF output can be used to supply the LNA with a filtered supply voltage.
☞A standard GNSS LNA has enough bandwidth to amplify GPS/GLONASS/BeiDou/Galileo signals.

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☞An external LNA is only required if the passive antenna is placed far away from the module. In that
case the LNA has to be placed directly to the passive antenna.
2.4.2 Active antenna design
An active antenna makes use of an integrated low-noise amplifier, which requires a power supply that
will contribute to the total GNSS system power consumption budget with additional 5 to 20 mA
typically.
If the supply voltage of the NEO-M8L module matches the supply voltage of the active antenna (for
example, 3.0 V), use the filtered supply voltage available at pin VCC_RF as shown in Figure 8.
Active antenna design using VCC_RF pin to supply the active antenna
Figure 8: Active antenna design, external supply from VCC_RF
If the VCC_RF voltage does not match with the supply voltage of the active antenna, use a filtered
external supply as shown in Figure 9.
For exact pin orientation, see the corresponding product Data sheet [1], [2], or [3] in the Related
documents section.
Active antenna design powered from an external supply
Figure 9: Active antenna design, direct external supply
☞The circuit shown in Figure 9 works with all u-blox M8 modules, also with modules without VCC_RF
output.

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3Automotive dead reckoning
3.1 Implementation
The NEO-M8L 3D dead reckoning modules make use of an internal 6-axis sensor (3-axis gyroscope
and 3-axis accelerometer), meaning that only speed pulse and forward/reverse information must be
provided externally. This can be done by applying speed pulse and forward/reverse signals directly at
the dedicated HW interface pins of the NEO-M8L (see section 1.5) or by transmitting the same
information to the module in UBX-ESF-MEAS messages (SW interface) sent from a host processor to
the module. Where the software interface is used, the customer can re-configure the hardware wheel
tick pin (as EXTINT) to indicate the reference time of the speed and forward/reverse information in
the following UBX message from the processor. Figure 10 shows the orientation of the IMU frame.
Figure 10: NEO-M8L with IMU sensor frame
☞More information about the ADR functionality can be found in the u-blox 8 / u-blox M8 Receiver
Description Including Protocol Specification [4].
3.2 Sensor calibration
The availability of “Sensor Fusion Mode” dead reckoning depends on the configuration of some
mandatory sensor characteristic data and optional parameter refinements. If only the mandatory
data are provided at installation, the navigation quality may be degraded on first use. The receiver
continuously refines sensor calibration to account for tire wear, temperature and aging. Data from
continuous calibration are stored for future use in non-volatile memory.
☞For more information about mandatory, calibration and optional configuration parameters, refer
to the ADR configuration section of u-blox 8 / u-blox M8 Receiver Description Including Protocol
Specification [4].
☞Note that the performance of the ADR solution relies on stable sensor location and orientation
with respect to the vehicle frame. The module must be mounted securely within the vehicle.
3.3 Software migration
☞For an overall description of the module software operation, see the u-blox 8 / u-blox M8 Receiver
Description Including Protocol [4].

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4Product handling
4.1 Packaging, shipping, storage and moisture preconditioning
For information pertaining to reels and tapes, Moisture Sensitivity levels (MSL), shipment and
storage information, as well as drying for preconditioning, see the corresponding product data sheet
[1], [2], or [3] or the u-blox Package Information guide [5] in the Related documents section.
Population of modules
☞When populating the modules, make sure that the pick and place machine is aligned to the copper
pins of the module and not on the module edge. Note that a MEMS device is present internally.
4.2 Soldering
Soldering paste
Use of "No Clean" soldering paste is highly recommended, as it does not require cleaning after the
soldering process has taken place. The paste listed in the example below meets these criteria.
Soldering paste: OM338 SAC405 / Nr.143714 (Cookson Electronics)
Alloy specification: Sn 95.5/ Ag 4/ Cu 0.5 (95.5% Tin/ 4% Silver/ 0.5% Copper)
Melting temperature: 217 °C
Stencil thickness: see section 2.3
The final choice of the soldering paste depends on the approved manufacturing procedures.
The paste-mask geometry for applying soldering paste should meet the recommendations.
☞The quality of the solder joints on the connectors (’half vias’) should meet the appropriate IPC
specification.
Reflow soldering
A convection type-soldering oven is highly recommended over the infrared type radiation oven.
Convection-heated ovens allow precise control of the temperature, and all parts will heat up evenly,
regardless of material properties, thickness of components and surface color.
As a reference for the professional grade NEO-M8L, see the IPC-7530 Guidelines for temperature
profiling for mass soldering (reflow and wave) processes, published in 2001. For the Automotive Grade
NEO-M8L-01A module, see the IPC/JEDEC J-STD-020E, December 2014.
Preheat phase
During the initial heating of component leads and balls, residual humidity will be dried out. Note that
this preheat phase will not replace prior baking procedures.
Temperature rise rate: max 3 °C/s. If the temperature rise is too rapid in the preheat phase it may
cause excessive slumping.
Time: 60 - 120 s. If the preheat is insufficient, rather large solder balls tend to be generated.
Conversely, if performed excessively, fine balls and large balls will be generated in clusters.
End temperature: 150 - 200 °C. If the temperature is too low, non-melting tends to be caused in
areas containing large heat capacity.
Heating/ Reflow phase
The temperature rises above the liquidus temperature of 217°C. Avoid a sudden rise in temperature
as the slump of the paste could become worse.

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For the professional grade NEO-M8L, limit time above 217 °C liquidus temperature to 40 - 60 s.
For the NEO-M8L-01A (automotive grade), the time above 217 °C should be limited to 60-150
seconds.
Peak reflow temperature for professional grade NEO-M8L is 245 °C, and for NEO-M8L-01A it is
250 °C.
Cooling phase
A controlled cooling avoids negative metallurgical effects of the solder (solder becomes more brittle)
and possible mechanical tensions in the products. Controlled cooling helps to achieve bright solder
fillets with a good shape and low contact angle.
Temperature fall rate: max 4 °C/s for the NEO-M8L, max 6 °C/s for the NEO-M8L-01A
☞To avoid falling off, the NEO-M8L module should be placed on the topside of the motherboard
during soldering.
The final soldering temperature chosen at the factory depends on additional external factors like
choice of soldering paste, size, thickness and properties of the base board, and so on. Exceeding the
maximum soldering temperature in the recommended soldering profile may permanently damage the
module.
Figure 11: Recommended soldering profile for the professional grade NEO-M8L
Figure 12: Recommended soldering profile for the automotive grade NEO-M8L-01A

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☞NEO-M8L modules must not be soldered with a damp heat process.
Optical inspection
After soldering the NEO-M8L modules, consider an optical inspection step to check whether:
The module is properly aligned and centered over the pads
All pads are properly soldered
No excess solder has created contacts to neighboring pads, or possibly to pad stacks and vias
nearby
Cleaning
In general, cleaning the populated modules is strongly discouraged. Residues underneath the
modules cannot be easily removed with a washing process.
Cleaning with water will lead to capillary effects where water is absorbed in the gap between the
baseboard and the module. The combination of residues of soldering flux and encapsulated water
leads to short circuits or resistor-like interconnections between neighboring pads.
Cleaning with alcohol or other organic solvents can result in soldering flux residues flooding into
the two housings, areas that are not accessible for post-wash inspections. The solvent will also
damage the sticker and the ink-jet printed text.
Ultrasonic cleaning will permanently damage the module, in particular the quartz oscillators.
The best approach is to use a "no clean" soldering paste and eliminate the cleaning step after the
soldering.
Repeated reflow soldering
Only single reflow soldering processes are recommended for boards populated with NEO-M8L
modules. To avoid upside down orientation during the second reflow cycle, the NEO-M8L module
should not be submitted to two reflow cycles on a board populated with components on both sides. In
this case, the module should always be placed on that side of the board, which is submitted into the
last reflow cycle. The reason for this (besides others) is the risk of the module falling off due to the
significantly higher weight in relation to other components.
Two reflow cycles can be considered by excluding the above described upside down scenario and
taking into account the rework conditions described in section 4 .
☞Repeated reflow soldering processes and soldering the module upside down are not
recommended.
Wave soldering
Base boards with combined through-hole technology (THT) components and surface-mount
technology (SMT) devices require wave soldering to solder the THT components. Only a single wave
soldering process is encouraged for boards populated with NEO-M8L modules.
Hand soldering
Hand soldering is allowed. Use a soldering iron temperature setting equivalent to 350 °C. Place the
module precisely on the pads. Start with a cross-diagonal fixture soldering (for example, pins 1 and
15), and then continue from left to right.
Rework
The NEO-M8L modules can be unsoldered from the baseboard using a hot air gun. When using a hot
air gun for unsoldering the module, a maximum of one reflow cycle is allowed. In general, using a hot
air gun is not recommended because this is an uncontrolled process and might damage the module.

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⚠Attention: use of a hot air gun can lead to overheating and severely damage the module. Always
avoid overheating the module.
After the module is removed, clean the pads before placing and hand soldering a new module.
⚠Never attempt a rework on the module itself, for example, replacing individual components. Such
actions immediately terminate the warranty.
In addition to the two reflow cycles, manual rework on particular pins by using a soldering iron is
allowed. Manual rework steps on the module can be done several times.
Conformal coating
Certain applications employ a conformal coating of the PCB using HumiSeal®or other related coating
products. These materials affect the HF properties of the NEO-M8L modules and it is important to
prevent them from flowing into the module. The RF shields do not provide 100% protection for the
module from coating liquids with low viscosity; therefore, care is required in applying the coating.
☞Conformal coating of the module will void the warranty.
Casting
If casting is required, use viscose or another type of silicon potant. The OEM is strongly advised to
qualify such processes in combination with the NEO-M8L modules before implementing this in the
production.
☞Casting will void the warranty.
Grounding metal covers
Attempts to improve grounding by soldering ground cables, wick or other forms of metal strips
directly onto the EMI covers is done at the customer's own risk. The numerous ground pins should be
sufficient to provide optimum immunity to interferences and noise.
☞u-blox makes no warranty for damages to the NEO-M8L modules caused by soldering metal cables
or any other forms of metal strips directly onto the EMI covers.
Use of ultrasonic processes
Some components on the u-blox M8 module are sensitive to ultrasonic waves. Use of any ultrasonic
processes (cleaning, welding etc.) may cause damage to the GNSS receiver.
☞u-blox offers no warranty against damages to the NEO-M8L modules caused by any ultrasonic
processes.

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4.3 EOS/ESD/EMI precautions
When integrating GNSS positioning modules into wireless systems, careful consideration must be
given to electromagnetic and voltage susceptibility issues. Wireless systems include components
that can produce Electrical Overstress (EOS) and Electro-Magnetic Interference (EMI). CMOS devices
are more sensitive to such influences because their failure mechanism is defined by the applied
voltage, whereas bipolar semiconductors are more susceptible to thermal overstress. The following
design guidelines are provided to help in designing robust yet cost-effective solutions.
⚠Only Separated or Safety Extra-Low Voltage (SELV) circuits are to be connected to the module
including interfaces and antennas.
⚠To avoid overstress damage during production or in the field it is essential to observe strict
EOS/ESD/EMI handling and protection measures.
⚠To prevent overstress damage at the receiver RF_IN, never exceed the maximum input power.
Electrostatic discharge (ESD)
Electrostatic discharge (ESD) is the sudden and momentary electric current that flows
between two objects at different electrical potentials caused by direct contact or
induced by an electrostatic field. The term is usually used in the electronics and other
industries to describe momentary unwanted currents that may cause damage to
electronic equipment.
ESD handling precautions
ESD prevention is based on establishing an Electrostatic Protective Area (EPA). The EPA can be a
small working station or a large manufacturing area. The main principle of an EPA is that there are no
highly charging materials near ESD sensitive electronics, all conductive materials are grounded,
workers are grounded, and charge build-up on ESD sensitive electronics is prevented. International
standards are used to define typical EPA and can be obtained for example from International
Electrotechnical Commission (IEC) or American National Standards Institute (ANSI).
GNSS positioning modules are sensitive to ESD and require special precautions when handling.
Particular care must be exercised when handling patch antennas, due to the risk of electrostatic
charges. In addition to standard ESD safety practices, the following measures should be taken into
account whenever handling the receiver.
Unless there is a galvanic coupling between the local GND (that is,
the work table) and the PCB GND, then the first point of contact
when handling the PCB must always be between the local GND and
PCB GND.
Before mounting an antenna patch, connect ground of the device.
When handling the RF pin, do not come into contact with any
charged capacitors and be careful when contacting materials that
can develop charges (e.g. patch antenna ~10 pF, coax cable ~50 -
80 pF/m, soldering iron).
To prevent electrostatic discharge through the RF input, do not
touch any exposed antenna area. If there is any risk that such
exposed antenna area is touched in non-ESD protected work area,
implement proper ESD protection measures in the design.

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When soldering RF connectors and patch antennas to the
receiver’s RF pin, be sure to use an ESD-safe soldering iron (tip).
⚠Failure to observe these precautions can result in severe damage to the GNSS module!
ESD protection measures
⚠GNSS positioning modules are sensitive to Electrostatic Discharge (ESD). Special precautions are
required when handling.
☞For more robust designs, employ additional ESD protection measures. Using an LNA with
appropriate ESD rating can provide enhanced GNSS performance with passive antennas and
increases ESD protection.
Most defects caused by ESD can be prevented by following strict ESD protection rules for production
and handling. When implementing passive antenna patches or external antenna connection points,
then additional ESD measures can also avoid failures in the field as shown in Figure 13.
Small passive antennas (<2 dBic and
performance critical)
Passive antennas (>2 dBic or
performance sufficient)
Active antennas
A
RF_IN
GNSS
Receiver
LNA
B
L
RF_IN
GNSS
Receiver
C
D
RF_IN
GNSS
Receiver
LNA with appropriate ESD rating
Figure 13: ESD precautions
☞Protection measure A is preferred because it offers the best GNSS performance and best level of
ESD protection.
Electrical Overstress (EOS)
Electrical Overstress (EOS) usually describes situations when the maximum input power exceeds the
maximum specified ratings. EOS failure can happen if RF emitters are close to a GNSS receiver or its
antenna. EOS causes damage to the chip structures. If the RF_IN is damaged by EOS, it is hard to
determine whether the chip structures have been damaged by ESD or EOS.
EOS protection measures
☞For designs with GNSS positioning modules and wireless (e.g. GSM/GPRS) transceivers in close
proximity, ensure sufficient isolation between the wireless and GNSS antennas. If wireless power
output causes the specified maximum power input at the GNSS RF_IN to be exceeded, employ
EOS protection measures to prevent overstress damage.
For robustness, EOS protection measures as shown in Figure 14 are recommended for designs
combining wireless communication transceivers (e.g. GSM, GPRS) and GNSS in the same design or in
close proximity.