Title:
Correlation of Flip Chip Underfill Process Parameters and Material Properties with In-Process Stress Generation
Correlation of Flip Chip Underfill Process Parameters and Material Properties with In-Process Stress Generation
Authors
Wong, C. P.
Palaniappan, Prema
Baldwin, Daniel F.
Selman, Paul J.
Wu, Jiali
Palaniappan, Prema
Baldwin, Daniel F.
Selman, Paul J.
Wu, Jiali
Authors
Person
Advisors
Advisors
Associated Organizations
Organizational Unit
Organizational Unit
Series
Collections
Supplementary to
Permanent Link
Abstract
Electronic packaging designs are moving toward
fewer levels of packaging to enable miniaturization and to increase
performance of electronic products. One such package
design is flip chip on board (FCOB). In this method, the chip is attached face down directly to a printed wiring board (PWB). Since
the package is comprised of dissimilar materials, the mechanical
integrity of the flip chip during assembly and operation becomes
an issue due to the coefficient of thermal expansion (CTE)
mismatch between the chip, PWB, and interconnect materials.
To overcome this problem, a rigid encapsulant (underfill) is
introduced between the chip and the substrate. This reduces
the effective CTE mismatch and reduces the effective stresses
experienced by the solder interconnects. The presence of the
underfill significantly improves long term reliability. The underfill
material, however, does introduce a high level of mechanical
stress in the silicon die. The stress in the assembly is a function of
the assembly process, the underfill material, and the underfill cure
process. Therefore, selection and processing of underfill material
is critical to achieving the desired performance and reliability.
The effect of underfill material on the mechanical stress induced
in a flip chip assembly during cure was presented in previous
publications. This paper studies the effect of the cure parameters
on a selected commercial underfill and correlates these properties
with the stress induced in flip chip assemblies during processing.
Sponsor
Date Issued
1999-01
Extent
1301459 bytes
Resource Type
Text
Resource Subtype
Article