Capsulization


Reading time ( words)

Since lead-free implementation, concerns about tin whiskers have intensified. For the past 12 years, studies and research by various laboratories and organizations have delivered burgeoning reports and papers, and my column has devoted an entire series to this subject. This article aims to capsulize the important areas of the subject. (Note: For expression, “whisker” is used as both noun and verb.)

The tin whisker issue and its potential mishaps have been recognized for more than six decades in electronic, electrical, and industrial applications. Some metals are prone to whiskering, or protruding from the surface of the substrate. In addition to tin, the metals that have exhibited whiskers include zinc, cadmium, silver, gold, aluminum, copper, lead, and others.

The whiskering phenomenon is distinct and unique. It is the result of a process different from other known phenomena (e.g., dendrites). And tin whisker and tin pest are separate metallurgical phenomena (SMT Magazine, May 2013). However, whiskers share commonality with dendrites in two aspects: Both are the result of a physical metallurgical process, thus following the science of physical metallurgy; and both could cause a product failure.

Uncertainty about tin whisker growth is most insidious. Stock markets do not like uncertainty, nor does the electronics industry. Our effort is to alleviate the uncertainty.

Practical Criteria

As some metals can whisker when accommodating conditions are met, the goal should be set with the differentiation between whisker-resistant and whisker-proof.

Overall, for testing or evaluation of the whisker propensity of a system, the key questions to be addressed are, is the system whisker-prone or whisker-resistant (not whisker-proof), and how does the system’s whisker resistance stand in reference to the intended benchmark?

Read the full article here.


Editor's Note: This article originally appeared in the July 2014 issue of SMT Magazine.

Share


Suggested Items

Reliability of ENEPIG by Sequential Thermal Cycling and Aging

11/06/2017 | Reza Ghaffarian, Jet Propulsion Laboratory, California Institute of Technology
Electroless nickel/electroless palladium/immersion gold (ENEPIG) surface finish for PCBs has now become a key surface finish that is used for both tin-lead and lead-free solder assemblies. This article presents the reliability of LGA component packages with 1156 pads assembled with tin-lead solder onto PCBs with an ENEPIG finish and then subjected to thermal cycling and then isothermal aging.

Achieving the Perfect Solder Joint: The Many Perspectives on Soldering

10/30/2017 | Stephen Las Marias, I-Connect007
For this month's issue of SMT Magazine, we brought several experts together to discuss the many aspects of soldering, from solder paste, to automation, inspection, and the challenges in achieving the perfect solder joint. We also talked about the strategies and parameters to consider to ensure reliable, good solder joints.

Is Hybrid Technology Gaining Momentum?

10/02/2017 | Dieter G. Weiss, Weiss Engineering
Over the past 20 years, ceramic hybrids have changed more and more to a backyard living in the European electronics industry, mainly driven by price pressure, specifically from the automotive electronics industry.



Copyright © 2017 I-Connect007. All rights reserved.