Hi Technos,

I've got an annoying one. I am looking at an assembly for automotive, which
has 100+ SMT resistor and capacitor pads with vias in them, on both sides of
the 9 layer PCB. Now, I know that I will expect solder starvation, since the
solder will flow into the via. I could eventually patch this by plugging the
vias on the opposite sides of the concerned pads and make slightly bigger
apertures in the stencil. Or even charge more and touch-up all the opens.

But what does via in pad mean in terms of reliability?

1. There will be voids, which are going to become even more important on
lead-free (the customer is after the european market). Any reliability
concerns related to that? Once again, I'm talking automotive.

2. PTH reliability. 100+ vias will have totally random quantities of solder
in them. I remember one of Werner's contributions (Entschuldigung Herr
Engelmeier, aber... I lost the e-mail) saying that less than 50% fill
degrades the reliability. Am I right?

A good fix would be, in case they refuse to re-spin the board and move the
vias, to fill the holes. What kind of specification should I issue for
filling, in terms of material and fill percentage?

Any other concerns?

Thanks,
Ioan

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