LEXI-R422 - System integration manual
UBX-23007449 - R02
Handling and soldering
Page 88 of 108
C1-Public
3.3
Soldering
3.3.1
Soldering paste
"No Clean" soldering paste is strongly recommended for LEXI-R422 modules, as it does not require
cleaning after the soldering process has taken place. The paste listed in the example below meets
these criteria.
Soldering 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 °C
Stencil Thickness:
130 µm for base boards
The final choice of the soldering paste depends on the approved manufacturing procedures.
The paste-mask geometry for applying soldering paste should meet the recommendations in
section
☞
The quality of the solder joints should meet the appropriate IPC specification.
3.3.2
Reflow soldering
A convection type soldering oven is strongly recommended
for LEXI-R422 modules over the infrared
type radiation oven. Convection heated ovens allow precise control of the temperature and all parts
will be heated up evenly, regardless of material properties, thickness of components and surface color.
Consider the
“
IPC-7530A Guidelines for temperature profiling for mass soldering (reflow and wave)
processes”.
Reflow profiles are to be selected according to the following recommendations.
⚠
Failure to observe these recommendations can result in severe damage to the device!
Preheat phase
Initial heating of component leads and balls. Residual humidity will be dried out. Note that 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 s
•
Peak reflow temperature: +245 °C
