Hi!

Due to the wave soldering process for PTH components, our assembly
process guideline
indicate to cover vias with soldermask in those areas.
But as you know, Plated thru hole vias covered with soldermask on both
sides with HASL 
solder or other manufacturing chemicals might be clogged in the vias and
out-gas (blow out) 
during assembly or remain in the hole and corroid the copping in the
via.

There are two suggestions from our PCB suppliers:

 Resolution1: PCB supplier to add a clearance to the soldermask: (drill
size plus.15mm). 
	With this option, we are not going to have the via covered, but
I am not sure if this is enough
	to avoid problems (pearls, solder passing through the via...)
during wave soldering process.

Resolution2: PCB supplier will tent the vias on both sides by adding a
barrel relief to prevent their 
	assembly problems.

In your opinion, what would be the best option? Is there an alternative
option you may see?

Thank you very much in advance,

Erika E. Sanchez
Siemens VDO 
Guadalajara Development Center
E-Mail: [log in to unmask]
Internet: http://www.siemensvdo.com

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