A Study of Underfill Dispensing Process

Abstract

The underfill dispensing process has been studied through material characterization and application of statistical tools. Coefficient of Planar Penetrance (COPP) introduced by Schwiebert and Leong 3 was used to evaluate the flow performance of three types of underfills. It is dependent on the viscosity, the surface tension, and the wetting angles of the underfill / substrate materials. In addition, the estimated flow times for that underfill can be calculated using Schwiebert and Leong's model with know die size. With the underfill material selected based on COPP, the temperature setting of various heating stations of a dispensing machine was evaluated using the statistical method targeting to setup the mass production equipment at the optimum operating point. The C-Mode Scanning Acoustics Microscopy (C-SAM) was used to assess the ability of the setup to provide a void free process. The results show that the actual flow times obtained are about 30 % higher than the predicted ones. It was also observed that void formation occurred when there was insufficient underfill filling in the gap between the die and the substrate.

14 Figures and Tables

Showing 1-8 of 8 references

Impact of Underfill Filler Particles on Reliability of Flip Chip Interconnects

  • Krishna Darbha, Juscelino Hozumi Okura, Abhijit Dasgupta
  • 1998

The Role of Microscopy in Semiconductor Failure Analysis

  • B Richards, P K Footner
  • 1992

Introduction to Colloid and Surface Chemistry

  • J S Duncan
  • 1986

Mechanics of Fluids

  • B S Messey
  • 1983

Handbook of Adhesive

  • S Irving
  • 1977

Number4, Fourth Quarter 1999 (ISSN 1063-1674) Intl. Journal of Microcircuits and Electronic Packaging