Integration Manual

LISA-U2 series - System Integration Manual
UBX-13001118 - R25 Handling and soldering Page 159 of 182
Preheat phase
Initial heating of component leads and balls. Residual humidity will be dried out. This preheat phase
will not replace prior baking procedures.
 Temperature rise rate: max 3 °C/s – If the temperature rise is too rapid in the preheat phase, it may
cause excessive slumping.
 Time: 60 – 120 s – If the preheat is insufficient, rather large solder balls tend to be generated.
Conversely, if performed excessively, fine balls and large balls will be generated in clusters.
 End Temperature: 150 - 200 °C – If the temperature is too low, non-melting tends to be caused in
areas containing large heat capacity.
Heating/ reflow phase
The temperature rises above the liquidus temperature of +217 °C. Avoid a sudden rise in temperature
as the slump of the paste could become worse.
 Limit time above +217 °C liquidus temperature: 40 - 60 seconds
 Peak reflow temperature: +245 °C
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, 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.
⚠ 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 74: Recommended soldering profile
☞ LISA-U2 modules must not be soldered with a damp heat process.