Stacking two or more packages that have been fully tested, burned-in and verified as ‘known good devices,’ is now a reality thanks to a new development from Amkor Technology.
Amkor’s Stacked etCSP packages, as they are known, provide flexibility to designers who require the performance of an extremely thin, multiple-chip system, but who lack space on a motherboard.
‘Stacked etCSP designs allow a ‘system in a stack’ approach to mixing different technologies such as memory, logic and mixed signal in a thin or small form factor,’ said David Zoba, Amkor’s etCSP product manager.
A single package has a total height of 0.35 to 0.5 mm, while stacks of two and three packages have mounted heights that range between 0.7 – 1.0 mm and 1.1 – 1.7 mm, respectively. For higher stacks, package thickness depends on the number of printed circuit layers required in the high-density package on the bottom of the stack, according to Zoba.
The initial adoption for the etCSP package was in PCMCIA Type II removable hard disk drives. Stacked etCSP packages are being evaluated for application in MP3 players and memory cards that use high-capacity flash memory devices requiring test and burn-in before stacking to eliminate the risk of device yield loss.
Other areas of interest for the stacked etCSP design include cell phone and personal communication applications where features and functions continue to be added without compromising size and weight reduction roadmaps.
The base etCSP package is constructed from a thin-core organic laminate with full sized 0.3 mm diameter solder balls on a standard 0.5 mm pitch.