IWLPC (Wafer-Level Packaging) Conference Proceedings

Wafer Spray Coating For Pre-Applied Underfill

Authors: Akira Morita and James Klocke
Company: Nordson ASYMTEK
Date Published: 11/5/2012   Conference: IWLPC (Wafer-Level Packaging)

Abstract: Recently, the process of pre-applying underfill onto a wafer is getting attention in 3D packaging. The pre-applied underfill material is placed on the bumped side of the wafer before dicing. Then the dies (with underfill) are stacked on another chip or wafer after dicing. There are a few ways to apply underfill onto the wafer: vacuum lamination, spin coating, and spray coating. Each of them has different challenges.

  • Vacuum lamination needs expensive vacuum lamination equipment.
  • Spin coating has material wastage.
  • Spray coating must make consistent coating thickness over wafer.

    This paper will demonstrate that using our experience with conformal coating and jet dispensing, we have evaluated wafer spray coating for pre-applied underfill application. This paper will present how we address the thickness consistency and wastage reduction challenges when using wafer spray coating.

  • Key Words: 

    3D package, underfill, pre-applied, wafer coating, spray coating, material wastage

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