Hi all,
One of the designers came with an idea: he has a high power component.
The space he has for a heat sink is small, so he wants to dissipate the
heat through the power layers. The component is a BGA, so the idea is to
put it on a metallic-capped via-in-pad by designing pad diameter of 24
mils, then define the solder area to 18 mils by solder mask.
Two questions:
1.      Provided the temperature may rise to 120 degC, and the laminate
is high Tg low cost FR4 - are there any potential risks to the long term
reliability?

2.      Are there any restrictions/hazards on deployment of defined
pads?

Regards
Ofer Cohen
Manager - Quality Assurance and Reliability
SIEMENS COM FN A SB

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