Advanced wire bond looping technology for emerging packages

Advanced packaging requirements for emerging semiconductor devices continue to present new challenges to the wire bond process. As an alternative to reducing pad pitch on high I/O applications, multi-tiered pad arrangements are typically found in production today with two, three or even four rows of bond pads. The growth of stacked die packages, and its requirement for a low profile, also challenges the wire bonding process. This paper examines looping advancements in today´s wire bonders that have been developed to meet the unique challenges associated with multi-tied and stacked die applications. Featured looping profiles include both forward and reversed bonding and the newly developed folded forward and lateral looping profiles. The advantages and trade-offs for each profile are outlined in the article. Capabilities including minimal loop height, productivity, fine pitch capability, and wire sweep resistance are compared for the different types of trajectories. In addition to looping trajectories, copper wire advantages are discussed in the context of a 60μm quad-tier demonstration. Driven by the complexity of multi-layered looping applications, a new K&S test device has been designed and produced in collaboration with key customers. The die will be used for developing multi-tiered approaches to ultra-high density packaging with wire bond interconnects.