SMTA International Conference Proceedings


RELIABILITY AND FAILURE MODE ANALYSIS OF A VOID FREE HYBRID NO-FLOW UNDERFILL PROCESS

Authors: Daniel F. Baldwin, Ph.D. and Michael Colella
Company: Engent, Inc. and Intel Corporation
Date Published: 10/11/2007   Conference: SMTA International


Abstract: The formation of underfill voids is an area of concern in the low cost, high throughput, or “no-flow” flip chip assembly process. A novel hybrid process has been developed that combines a capillary underfill flow dynamic with no-flow fluxing underfills to result in near void-free assemblies. This new hybrid no-flow process is reviewed in this work. Systematic reliability testing and the associated failure analysis has been conducted for the new hybrid process. The results presented in this paper compare conventional no flow underfill process with the new hybrid process. Flip chip test vehicles were assembled according to an optimal process developed for four commercially available no-flow underfills. Two reliability tests were used to evaluate the new process. Accelerated reliability tests performed included air/air thermal cycling and autoclave testing. The newly developed edge patterned hybrid no-flow process has resulted in near void-free assemblies capable of passing 2000 cycles without failure for the -40 to 125 °C thermal cycle reliability test. The results and failure analysis for this reliability testing is detailed. The new process has potential to avoid the problem of early solder extrusion into underfill voids during thermal and thermomechanical stressing of the assemblies. The overall reliability performance for the new process is exceptional relative to conventional no flow processing techniques.

Key words: flip chip, reliability, no flow underfill, failure analysis



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.


Back


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

Phone +1 952.920.7682
Fax +1 952.926.1819