Integration Manual
SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R13 Handling and soldering Page 91 of 119
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To avoid falling off, modules should be placed on the topside of the motherboard during soldering.
The soldering temperature profile chosen at the factory depends on additional external factors like choice of soldering
paste, size, thickness and properties of the base board, etc.
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Exceeding the maximum soldering temperature and the maximum liquidus time limit in the recommended soldering
profile may permanently damage the module.
Preheat Heating Cooling
[°C] Peak Temp. 245°C [°C]
250 250
Liquidus Temperature
217 217
200 200
40 - 60 s
End Temp. max 4°C/s
150 - 200°C
150 150
max 3°C/s 60 - 120 s
100
Typical Leadfree
100
Soldering Profile
50 50
Elapsed time [s]
Figure 56: Recommended soldering profile
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The modules must not be soldered with a damp heat process.
3.3.3 Optical inspection
After soldering the module, inspect it optically to verify that it is correctly aligned and centered.
3.3.4 Cleaning
Cleaning the modules is not recommended. 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. Water will also damage the sticker and the ink-jet printed text.
• 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.
For best results, use a "no clean" soldering paste and eliminate the cleaning step after the soldering.
3.3.5 Repeated reflow soldering
Repeated reflow soldering processes and soldering the module upside-down are not recommended.
Boards with components on both sides may require two reflow cycles. In this case, the module should always be placed
on the side of the board that 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.