I read an article some time ago concerning fine pitch components like QFP 20 mil or less and their yield performance.  It had a table that listed several manufactures and a comparison of BGA vs. QFP.  The table showed how the yield would drop once you started pacing 16 mil QFP components. 

 

I need this data so I can respond to a yield issue we have with one of our assemblies.  The assembly has 20 thousand SMT solder connections, and ~three thousand connections are “twelve QFP184 16 mil pitch parts”.  We also have some 8-pin resistor networks “LLC” that a pin shows evidence of not wetting to the land.  The resistor network accounts for 2,936 solder connections on the board as well.  We usually run ten boards at a time and yield 50% FPY.

 

Any information concerning this issue would be appreciated.

 

Thanks in advance,

 

Scott