Sponsor

Plan Ahead for BGA Device Upgrades
BGA Socket Adapter Systems convert surface mount device packages to through-hole (pinned) assemblies, making it easy to plug and unplug SMT devices in the field or the test lab.
Advanced Interconnections Corp.

Rentals and Rent to Purchase x-ray Systems

Sponsor

Maybe it's the thermocouple connection
If your thermal profiling readings seem inconsistent, the culprit could be your thermocouple attachment method. A recently conducted study revealed some interesting findings.
ECD

What is the Reliability of Reballed BGAs?

Will the process of re-balling lead-free BGA components with tin-lead solder balls yield quality connections better or worse than soldering using tin-lead paste?

DOWNLOAD

Authored By:

M.H. Biglari, A. Nazarian, R. Denteneer, M. Biglari, Jr.
Mat-Tech BV, The Netherlands

A.A. Kodentsov
Laboratory of Materials and Interface Chemistry, Eindhoven University of Technology, The Netherlands

Summary

Due to the obsolescence of SnPb BGA components, electronics manufacturers that use SnPb solder paste either have to use lead-free BGAs and adjust the reflow process or re-ball these components with SnPb balls. The reliability of Lead-Free and Lead-Containing solder joints for BGA's has been investigated after re-balling using optimal microscopy. The goal was to compare the quality of the connections for both options. For the lead-free BGA, voids produced by the release of volatile species in flux during soldering were present. Large voids have been observed at the interface component/solder.

Using components that were re-balled did not show the amount of voiding observed for the lead-free BGA. Kirkendall voiding has been observed for the lead-free component at the component/solder interface. It has been therefore concluded that the use of the reballed components is to be preferred to adjusting the reflow profile and using lead-free components.

Conclusions

The reliability of a SAC ball/SnPb solder BGA connection has been investigated and compared with the reliability of a re-balled SnPb ball/SnPb solder BGA connection.

Large voids are observed for the mixed connection
Kirkendall voids are present at the component/solder interface of the mixed connection
A thoroughly mixed connection was achieved for the mixed connection (i.e. there was no visible distinction between a SAC region and SnPb region of the solder connection)
The thickness of intermetallic layer between solder and component is comparable for both samples
The thickness of intermetallic layer between solder and PCB is comparable for both samples
The re-balled sample was of good quality

It can therefore be concluded that re-balling lead-free BGAs with SnPb balls, if done properly, should yield better quality connections than soldering lead-free BGAs with SnPb solder paste.

Initially Published in the IPC Proceedings

Free Newsletter Subscription
Circuitnet is built for professionals who bear the responsibility of looking ahead, imagining the future, and preparing for it.

Insert Your Email Address

Sponsor

RAIG Minimizes Corrosion, Allows Higher Gold on ENEPIG
Paper describes a mixed reaction RAIG electrolyte that minimizes galvanic corrosion and allows higher ENEPIG gold thicknesses, enabling robust designs and world-class quality on target with minimal variation.
Uyemura