I was talking recently with a fabless semiconductor company whose designers were confused about their foundry's strategy for design-for-yield.  They asked me whether they should follow the foundry's guidelines on yield, or formulate their own yield strategy to complement what the foundry had recommended. 

I asserted that yield is much too important to leave to the foundry.  In most cases, foundries are in the business of selling wafers, not working chips.  Aside from competitive pressure to deliver working silicon, why should foundries care about yield? 

I will be interested to hear from any of you who have anecdotal evidence of foundries' commitment to yield - or othewise!