SMTA International Conference Proceedings

X-Ray Micro-Computed Tomography Based FE-Models to Capture Realistic Manufacturing Variability in Cu-Al Wirebonds and Solder-Joints in QFNs

Authors: Pradeep Lall, Madhu Kasturi, Nakul Kothari, David Locker
Company: Auburn University and US Army CCDC Aviation & Missile Center
Date Published: 9/22/2019   Conference: SMTA International

Abstract: QFN packages have found extensive applications in automotive and defense electronics. Electronic components comprise many material-interfaces between EMC (Epoxy mold compound), wire bonds, aluminum pads, silver die, die attachment adhesive and lead frame. Making traditional CAD model, mesh and FE models for electronic packages is time-consuming. In addition, nominal modeled geometry may not include manufacturing variabilities from molding and bonding processes. In this paper, a new method to create finite-element models based on x-ray micro-computed tomography data of the actual part assembly has been presented. The method has been applied to assembled QFN parts for assessment of stresses at various interfaces and solder joints during thermal cycling. Effect of EMC properties on the stresses at the various interfaces, Cu-Al wirebond interconnects, and solder joints in the presence of voiding has been studied. Life prediction has been pursued using the inelastic strain energy density based damage relationship. The model has been validated with experimental data.

Key Words: 

Copper wirebonds, Solder Joints, Green EMC, CT technique, QFN

Members download articles for free:

Not a member yet?

What else do you get when you join SMTA? Read about all of the benefits that go along with membership.

Notice: Sharing of articles is restricted to just your immediate work group. Downloaded papers should not be stored on an external network or shared on the internet.


SMTA Headquarters
6600 City West Parkway, Suite 300
Eden Prairie, MN 55344 USA

Phone +1 952.920.7682
Fax +1 952.926.1819