u-blox SARA-R4 Series System Integration Manual

Contents

SARA-R4 series - System Integration ManualUBX-16029218 - R06 Handling and solderingPage 81 of 102To 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 ofsoldering paste, size, thickness and properties of the base board, etc.Exceeding the maximum soldering temperature and the maximum liquidus time limit in therecommended soldering profile may permanently damage the module.Preheat Heating Cooling[°C] Peak Temp. 245°C [°C]250 250Liquidus Temperature217 217200 20040 - 60 sEnd Temp. max 4°C/s150 - 200°C150 150max 3°C/s 60 - 120 s100 Typical Leadfree 100Soldering Profile50 50Elapsed time [s]Figure 43: Recommended soldering profileThe modules must not be soldered with a damp heat process.3.3.3 Optical inspectionAfter soldering the SARA-R4 series modules, inspect the modules optically to verify that the module is properlyaligned and centered.3.3.4 CleaningCleaning the modules is not recommended. Residues underneath the modules cannot be easily removed with awashing process. Cleaning with water will lead to capillary effects where water is absorbed in the gap between the baseboardand the module. The combination of residues of soldering flux and encapsulated water leads to short circuitsor 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 twohousings, areas that are not accessible for post-wash inspections. The solvent will also damage the stickerand 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.