Note: Underneath the text are three "related stories," all dated today (Apr 17). EETimes allows two free views a day (from each computer). So I can tell you the third story ("TSMC's Chang: 'The worst is behind us' on 28-nm") quotes Mr Chang as saying that the difficulty with 28 nm was never about yield--but about capacity, which was resolved when TSMC bought more tools a year ago.