Tessera Packaging Article

Mobile Handset Design Line: Tessera R&D Director Giles Humpston discusses tips and trics of camera phone module packaging with emphasis on edge vs. TSV contacts. Here is what he says about TSV technology:

"despite many years of endeavour through silicon via (TSV) technology, as it is called, has failed to be widely adopted because of the need for specialist capital equipment to fabricate the via and the reliability of TSV interconnects has not been satisfactorily solved at a competitive cost.

The only wafer-level package solution adopted by industry in high volume is edge contacts."

About Tessera edge contact:

"Edge contacts have a minor drawback in that die on the wafer have to be spaced slightly wider apart than usual to provide access to create the structures. Consequently, the maximum number of die that can fit on a wafer is decreased, slightly increasing unit cost. This issue is circumvented in the latest generation of wafer-level package for image sensors which use a via-through-pad interconnect... The interconnect is still an edge contact, but it is radially symmetric within the area of the bond pad. Not only does this permit the dicing lanes to be as narrow as the silicon design rules allow, but it removes many restrictions on the bond pad size, pitch and location, making this style of wafer-level package directly compatible with the majority of existing CMOS imagers."