LGAs (Land Grid Arrays) are increasingly being offered by major vendors.

All appear to have "proven" that these devices are extremely reliable if
the apps notes and websites are taken as evidence. The latest are
appearing with not just peripheral land patterns but multiple rings of
lands, all the way to full arrays. Some have a large heat slug which is
recommended to have thermal vias into PCB for cooling.

Having searched the TechNet archives and found opposing opinion dated
Jan 2006 from Mr. Stadem and Mr. Werner Engelmaier, both trusted
experts, I have some concerns regarding reliability in high-rel, -50 to
+125degC temp cycle spec environments with >4layer and/or >0.062" thick
PCBs, which seems to be what most of the vendors data is based upon.

Has anything changed?

Is this a way for the vendors to avoid balling devices?

Has anyone run some "independent" qualifications of these types of parts
that they could share summaries of?

Some vendors are recommending solder mask defined pads as on the device
giving 2-to-2.5mils standoff, concerned?

Thanks for your responses in advance,

Phil.

 


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