Encapsulated wafer level package technology (eWLCS)

This paper introduces a new encapsulated WLCSP product (eWLCS). The new product has a thin protective coating applied to all exposed silicon surfaces on the die. The applied coating protects the silicon and fragile dielectrics and prevents handling damage during dicing and assembly operations, effectively providing a durable packaged part in the form factor of a WLCSP. The manufacturing process leverages existing high volume manufacturing methods with exceptionally high process yields. In this process the silicon wafer is diced prior to the wafer level packaging process. The dice are then reconstituted into a new wafer form with adequate distance between the die to allow for a thin layer of protective coating to remain after final singulation. Standard methods are used to apply dielectrics, thin film metals, and solder bumps. The resulting structure is identical to a conventional WLCSP product with the addition of the protective sidewall coating. This paper discusses the key attributes of the new package as well as the manufacturing process used to create it. Reliability data will be presented and compared to conventional WLCSP products and improvements in package durability will be discussed and compared to conventional WLCSP.