u-blox M8 Series Hardware Integration Manual page 17

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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
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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.
UBX-16010549 - R08
C1-Public
NEO-M8L - Hardware integration manual
Product handling
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Page 17 of 28