Waferlevel

Waferlevel, in the context of semiconductor packaging, refers to processes that occur at the wafer stage rather than after individual dice are separated. The term is most commonly associated with wafer-level packaging (WLP), where interconnections and protective structures are added to the entire wafer through redistribution layers and bumping, enabling chip-scale packages that are close in size to the die itself.

Two widely used forms of wafer-level packaging are wafer-level chip-scale packaging (WLCSP) and fan-out wafer-level packaging (FO-WLP). WLCSP produces packages that mirror the die size, resulting in a very small footprint suitable for compact devices. FO-WLP expands the redistribution layer beyond the die edges and embeds the structure in a molded ring, allowing higher I/O density and greater flexibility for different package geometries.

Key technologies in waferlevel packaging include redistribution layers, copper bumps or solder bumping, and, in some cases, redistribution through silicon vias. The approach can reduce package height, shorten interconnect paths, and simplify assembly, which can lower costs in high-volume production and improve electrical performance for certain applications. However, waferlevel packaging presents design and manufacturing challenges, including tighter process control, yield management, and thermal dissipation considerations for higher-power devices.

Applications of waferlevel packaging are common in mobile devices, consumer electronics, sensors, and other high-volume products where small form factor and cost efficiency are critical. The technology continues to evolve with developments in fan-out formats, integration density, and heterogeneous integration.