LEA-M8F - Hardware Integration Manual
UBX-14000034 - R03
Early Production
Information
Product
handling
Page 21 of 30
Cooling phase
A controlled cooling avoids negative metallurgical effects (solder becomes more brittle) of the solder 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
To avoid falling off, the u-blox M8 GNSS 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, etc. Exceeding the maximum soldering
temperature in the recommended soldering profile may permanently damage the module.
Figure 15: Recommended soldering profile
u-blox M8 modules
must not
be soldered with a damp heat process.
Optical inspection
After soldering the u-blox M8 module, 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
easily be 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.
