User's Manual

LE920A4 HW User Guide Mounting the Module on Your Board
Doc#: 1VV0301261 Solder Paste
Rev. 4.3 Page 101 of 123 2017-12-07
Table 46: Recommendations for PCB Pad Surfaces
Finish
Layer Thickness
(um)
Properties
Electro-less Ni / Immersion
Au
3 –7 / 0.05 – 0.15
Good solder ability protection,
high shear force values
The PCB must be able to resist the higher temperatures that occur during the lead-free
process. This issue should be discussed with the PCB supplier. Generally, the wettability
of tin-lead solder paste on the described surface plating is better compared to lead-free
solder paste.
Solder Paste
It is recommended to use only “no clean” solder paste to avoid cleaning of the modules
after assembly.
10.7.1. Solder Reflow
Figure 28 shows the recommended solder reflow profile.
Figure 28: Solder Reflow Profile
Table 47: Solder Profile Characteristics
Profile Feature Pb-Free Assembly
Average ramp-up rate (T
L
to T
P
) 3°C/second max