Not a problem Colin,
No real difference if SMD or NSMD. Still need thermal relief for good
soldering characteristics.
Just that the SMD type pads tend to be larger. You'll start another
discussion on the pros and cons of SMD and NSMD pads for BGAs..... There is
a view that the solder mask defined pads tend to interrupt the smooth solder
fillet, creating an area in the solder joint where stresses can concentrate.
I've had no problems using the partial tenting method. Liquid solder masks
will not 'tent' reliably by their nature.
If you don't want holes under the BGA, perhaps your manufacturer can plug
the vias. (I've never asked for this and don't know of any manufacturers
here who could do it.)
Blind vias under the BGA would be another option.

regards,

Phil.

-----Original Message-----
From: Colin Weber [mailto:[EMAIL PROTECTED]]
Sent: Friday, 8 February 2002 08:51
To: Protel EDA Forum
Subject: Re: [PEDA] Thermal relief / Tenting


Thanks for the clarification Phil. Sorry if I misquoted you. That wasn't
my intention. Just to raise a debate. That worked :-)

Does the approach you take differ for SMD or NSMD pads, or is their
little difference for the case you cited below?

Also, as a side issue, what success/spec have you had with PBGA
Via tenting, partial or full? We cannot get full tenting guaranteed by
our manufacturer, in fact the results are quite poor, and I'm still
contemplating whether partial is satisfactory.

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