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Spheron WLCSP

Flip Chip's newest product offering for Wafer Level Chip Scale Packaging (WLCSP) utilizes a new dielectric material, which offers improved capacitance, reliability, and better compatibility to polyimide passivation verses BCB. In addition to the advanced polymer, Spheron WLPTM incorporates a new metal structure, which offers improved strength and electrical performance. Benefits of Spheron WLP include:

  • Improved electrical performance
  • Reduced capacitive coupling between UBM/Solder and the underlying IC circuitry
  • Improved solder joint reliability
  • Significant improvement in TC performance due to die planarization/polymer film characteristics
  • Elimination of incoming wafer topology issues.
Wafer Level Packaging

In addition, the planarized polymer film ensures proper UBM step coverage, even over non-planarized devices. Spheron is compatible with all device passivations; nitrides, oxides and polyimides.

As with UltraCSP, pre-formed solder balls of 250µm to 500µm are placed on the wafer and reflowed for final bump heights of 200µm to 400µm. In this process, the bumps can be placed directly on the device I/O's or the signal may be redistributed to a more desirable die location. Typically, the number of bumps per die is 4-100. Die bumped with Spheron WLP do not require underfill.

The Spheron WLP process may be used to bump directly on I/O or may be used to redistribute bumps to a more desirable die location. View an example of the redistributed process.