u-blox ZED-F9P Integration Manual page 105

Figure 77: Soldering Profile
Modules must not be soldered with a damp heat process.
Optical inspection
After soldering the module, consider an optical inspection step.
Cleaning
No cleaning with water, solvent, ultrasonic cleaner should be carried out:
• 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 modules.
Modules should not be submitted to two reflow cycles on a board populated with components on
both sides in order to avoid upside down orientation during the second reflow cycle. 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 this section.
Repeated reflow soldering processes and soldering the module upside down are not
recommended.
Wave soldering
UBX-18010802 - R02
Advance Information
9 Product handling
ZED-F9P - Integration Manual
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