eWLCSP™ (a FIWLP Technology)

encapsulated Wafer Level Chip Scale Package (eWLCSP™)


The combined benefits of superior quality, lower cost structure and low risk, seamless conversion path make this innovative encapsulated WLCSP technology a compelling value proposition over standard WLCSP.

The eWLCSP™ Advantage

  • Innovative FlexLine™ manufacturing approach delivers compelling cost reductions over standard WLCSP
  • Seamless conversion between fan-in and fan-out designs with the same basic package platform
  • Unique WLP manufacturing approach independent of incoming silicon wafer diameter
  • Quality built in by design delivers robust, reliable WLCSP solution

A Robust WLP Technology: eWLCSP™

Utilizing our FlexLine™ manufacturing approach, STATS ChipPAC offers an innovative encapsulated WLCSP technology called eWLCSP™. The FlexLine approach can deliver compelling cost reductions over standard WLCSP, enabling a unique WLCSP package that offers significant structural advantages over traditional WLCSP designs. eWLCSP provides a measurable increase in overall component break strength of more than 50% over traditional bare die WLCSP structures which are regularly exposed to potential cracking, chipping and handling issues that can occur before or during the SMT assembly process, especially in advanced node products where the die is very thin and dielectric layers are extremely fragile.

eWLCSP’s improved mechanical structure enables quality to be built in by design versus relying on costly inspection to weed out defects. The encapsulation material that is intrinsic to the FlexLine process forms a thin protective polymer casing on the back and four sidewalls of the die, providing mechanical robustness and resistance to chipping, cracking and handling damage, and enabling improved long term reliability over traditional bare die WLCSP.

Ease of Conversion, Lower Costs

An additional benefit is the ease of conversion from a standard WLCSP to an eWLCSP design. Customers can seamlessly transition from a fan-in to fan-out design within the same basic package platform. A product currently using a conventional WLCSP process can be converted to eWLCSP without a silicon design change, regardless of the current silicon wafer diameter. 300mm devices transitioning to advanced silicon nodes with fragile dielectric layers will especially benefit from conversion to eWLCSP. The FlexLine method can reduce WLCSP costs by 15-30% when using the optimum design requirements for WLCSP devices; e.g., 200mm incoming wafers can be reconstituted into 300mm or larger panel sizes, providing customers with the advantage of panel size scaling. Further per-unit cost reductions are achieved as the panel size increases.

FlexLine Process Flow

eWLCSP Features

  • Wafer agnostic process normalises wafer diameter to uniform processing size making incoming wafer size irrelevant
  • All processing performed in wafer form before dicing
  • eWLCSP structure identical to conventional WLCSP with exception of protective sidewall coating
  • Final back grind thins the package to desired thickness
  • Backside surface can be covered with mold compound, exposed with grind process or laminated with protective film
  • Spin-on low temp curable polymers
  • Standard photolithography; Plated Cu RDL, Plated Cu UBM
  • At least 30um routing space at package edge compared to Si WLCSP
  • Typical body thickness: ~300um
  • Same body sizes available as WLCSP (qualified up to 6x6mm); eWLCSP die size can be scaled beyond 6x6mm
  • Ball pitch 0.50mm, 0.40mm, 0.35mm
  • Fan-out panel/wafer level test before dicing
  • Package singulation without touching Si after testing

  • Polymer sidewall offers mechanical protection from die chipping, cracking and other handling issues
  • Greater than 50% increase in die strength over traditional WLCSP structures
  • Advanced dielectrics provide equal/better reliability and performance
  • Benefits optimal for larger WLCSP die sizes
  • Passes standard CLR, BLR, temperature cycle on board (TCoB) and drop test (equivalent to WLCSP)

  • Drop-in replacement offers low risk, seamless conversion path from standard WLCSP
  • Increased savings as panel sizes increase
  • FlexLine process qualified at advanced silicon nodes down to 22/20nm

eWLCSP Market Applications & Drivers

eWLCSP is a compelling solution for space constrained mobile devices and new applications such as wearable technology and automotive markets. Effective transition to eWLCSP is optimal for the following applications:
  • 200mm WLCSP migration to FlexLine for PMIC and MCU applications
  • 300mm WLCSP migration to eWLCSP for amplifiers, MCU, PMIC and RFIC applications