Here is the abstract you requested from the wirebond_2008 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|Addressing Challenges of Stacked Die Wire Bonding|
|Keywords: stacked dies, low looping, die with DAF|
|Thermosonic wire bonding has traditionally required surfaces which are sturdy, homogeneous, and well-clamped. However the advent and popularization of stacked die memory modules in recent years has introduced challenges not previously faced by wire bonders. Among these are: suspended die peripheries which literally bend during bonding, ultra thin dies as little as 50 microns diameter, dies laminated with die attach film that changes ultrasonic resonance of the silicon, and constant reduction of package thickness which requires continuous reduction of wire loop heights. Complicating matters further is the usage of copper wire rather than gold wire in some applications, and the constant pressure for enhanced productivity. Solutions to these challenges require first a study of the composition and interactions of the materials systems combined into stacked die modules. Then a fundamental re-analysis of wire bonder design and wire bond processing is needed, which encompasses nearly the full range of machine design from ultrasonic transducer performance, parameter selection, looping algorithms, and bonder Z drive controls. This paper will explore in depth the real world solutions designed and implemented to bring stacked die modules into high volume production with high yields and acceptable productivity. Illustrations, data and text will explain the problem and the solutions.|
|Shinichi Nishiura, Manager of Wire Bond Applications