WL865E4-P Module Hardware User Guide
1VV0301580 Rev. 4
Page
43
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56
2019-08-08
PCB pad dimensions
It is not recommended to place via or micro-via not covered by solder resist in an area of
0.3 mm around the pads unless it carries the same signal of the pad itself (see following
figure).
Figure 5: inhibit area for not solder covered vias
Holes in pad are allowed only for blind holes and not for through holes.
Recommendations for PCB pad surfaces:
Finish
Layer thickness [µm]
Properties
Electro-less Ni /
Immersion Au
3
–7 / 0.03 – 0.15
Good solderability protection,
high shear force values
Table 1910: PSB Finishing recommendation
The PCB must be able to resist the higher temperatures which are occurring at 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.
It is not necessary to panel the application PCB, however in that case it is suggested to use
milled contours and predrilled board breakouts; scoring or v-cut solutions are not
recommended.
Stencil
Stencil’s apertures layout can be the same of the recommended footprint (1:1), we suggest
a thickness of stencil foil ≥ 120 µm.
Solder paste
Lead free
Solder paste
Sn/Ag/Cu
Table 110:Recommended Solder Paste Type
