ultra chip-scale package (Maxim) (UCSP)
Ultra Chip-ScalePackage (UCSP) is a designation used by the Maxim company for a WLCSP package. The Maxim UCSP is built directly on the wafer, so it is a wafer level packaging(WLP).
The UCSP package is covered by a thin protective film designed to reduce mechanical stress when connecting the contacts and to electrically insulate the substrate surface. Like the CSP package, the UCSP package is no larger than the actual chip. The connections from the UCSP package are arranged as an array, as with the BGA package. There are versions with 2 x 2, 2 x 3, 3 x 3, 4 x 3, 4 x 4, 5 x 4, 5 x 5, 6 x 5 and 6 x 6 connections. Package sizes range from 1 mm x 1mm up to 3 mm x 3 mm.