u-blox ODIN-W260 System Integration Manual

u-blox ODIN-W260 System Integration Manual Manual pdf 21 page image

ODIN-W2 series - System Integration ManualUBX-14040040 - R03 Advance Information Handling and solderingPage 21 of 33Soldering Paste OM338 SAC405 / Nr.143714 (Cookson Electronics)Alloy specification 95.5% Sn / 3.9% Ag / 0.6% Cu (95.5% Tin / 3.9 % Silver / 0.6% Copper)95.5% Sn / 4.0% Ag / 0.5% Cu (95.5% Tin / 4.0% Silver / 0.5% Copper)Melting Temperature 217°CStencil Thickness 150 μm for base boardsTable 7: Soldering paste informationThe final choice of the solder paste depends on the approved manufacturing procedures. The paste-maskgeometry for applying solder paste should meet the recommendations in Module footprint and paste masksection.The quality of the solder joints on the connectors (’half vias’) should meet the appropriate IPCspecification.3.3.2 Reflow solderingA convection type-soldering oven is strongly recommended over the infrared type radiation oven. The convectionheated ovens allow precise control of the temperature and all parts will be heated up evenly regardless ofmaterial properties, thickness of components, and surface color.Consider the "IPC-7530 Guidelines for temperature profiling for mass soldering (reflow and wave) processes",published during 2001. Select the reflow profiles as per the following recommendations:Failure to observe these recommendations can result in severe damage to the device!Preheat phaseInitial heating of component leads and balls. Residual humidity will be dried out. Note that this preheat phasewill not replace prior baking procedures.• Temperature rise rate: maximum 3°C/s.If the temperature rise is too rapid in the preheat phase it may cause excessive slumping.• Time: 60 to 120 seconds:If the preheat is insufficient, rather large solder balls could be generated. Conversely, if performedexcessively, fine balls and large balls will be generated in clusters.• End Temperature: 150 to 200°C:If the temperature is too low, non-melting tends to be caused in areas containing large heat capacity.Heating and reflow phaseThe temperature rises above the liquidus temperature of 217°C. Avoid a sudden rise in temperature as the slumpof the paste could become worse.• Limit time above 217°C liquidus temperature: 40 to 60 s• Peak reflow temperature: 245°CCooling phaseA controlled cooling avoids negative metallurgical effects (solder becomes more brittle) of the solder andpossible mechanical tension in the products. Controlled cooling helps to achieve bright solder fillets with a goodshape and low contact angle.• Temperature fall rate: max 4°C/sThe modules should be placed on the topside of the motherboard during soldering to avoid falling off.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 and so on.Exceeding the maximum soldering temperature and the maximum liquidus time limit in therecommended soldering profile can permanently damage the module.