Intel: Design of Experiment

Objective

Intel and Enthone conducted a joint study to explore the process boundaries of AlphaSTAR immersion silver and to determine process limits for microvoid formation.

Results

Under all conditions of the DOE, the occurrence of planar microvoids was well within the acceptance criteria as established by Intel. No "caves," —defined as small (approximately 1 µm) enclosed cavities found in copper lands directly below the immersion silver—were found. The fabrication suppliers (known to produce microvoids with Silver "C-2") and microetch chemistry (copper roughness) had no statistically significant impact whatsoever. Furthermore, plating rate and silver thickness was not found to generate caves or microvoids. Successful, consecutive production data further validated the DOE results illustrated in the chart above.

Conclusion

The results generated from the DOE confirmed the earlier results of the historical production data to conclude that AlphaSTAR immersion silver is intrinsically resistant to microvoid occurrence.

Source: Intel Corporation approaches, experiments, and tests in a pre-production environment. Intel makes no guarantee of the same of similar results in your pre-production or manufacturing environment.

To view or download the AlphaSTAR Microvoid Study, click here.