HE920 Hardware User Guide
1vv0301014 Rev.9 – 2014-01-23
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Page 69 of 84
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).
Holes in pad are allowed only for blind holes and not for through holes.
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 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’s PCB, however in that case it is suggested to use
milled contours and predrilled board breakouts; scoring or v-cut solutions are not
recommended.
