1. Dr. H. Aglan, Tuskegee University
David Burdick, The Boeing Co.
Investigation into the
Mechanisms of Initiation and
Growth of Tin Whiskers and
the Risk Mitigation of
Occurrence of Induced Shorts

2. Tuskegee University:
Collaborative Research with the Boeing Company
Heshmat Aglan, Dean, College of Engineering
David Burdick, Associate Technical Fellow, the Boeing Company

3. TUSKEGEE
UNIVERSITY
1881
Overview

4. Tuskegee University Overview
The University
➢ Independent - State-related and Land Grant institution of higher
education
➢ The academic programs are organized into five colleges and two
schools
➢ The curricula for these colleges and schools currently offer over 50
degrees including 39 Bachelor's, 13 Master's, 3 Doctor's of
Philosophy: Materials Science and Engineering, Integrative Bio-
Sciences, Interdisciplinary Pathobiology and the Doctor of
Veterinary Medicine.
➢ Tuskegee enrolls more than 3,000 students and employs
approximately 800 faculty and support personnel.
➢ Physical facilities include more than 5,000 acres of forestry and a
campus on which sits more than 100 major buildings and structures

5. ➢ The university is the largest producer of African-Americans with baccalaureate
degrees in math, science and engineering in Alabama.
➢ Tuskegee’s Materials Science and Engineering Program graduates the largest number
of black PhD students in the U.S.
➢ Tuskegee University is the No. 1 producer of African-American aerospace engineers
in the nation.
➢ Tuskegee University is the only HBCU with a fully accredited College of Veterinary
Medicine that produces over 75 percent of the African-American Veterinarians.
➢ Tuskegee is the only college or university campus in the nation to be designated a
National Historic Site by the U.S. Congress.
➢ More U.S. presidents have visited Tuskegee University than any other HBCU.
➢ The Tuskegee Airman, who trained at the Tuskegee Air Field in July 1941, were the
first African-American fighter pilots in the U.S. Army Air Corps.
➢ The ROTC program at Tuskegee has produced more African-American general
officers in the military than any other institution, including the service academies.
➢ Tuskegee University is the only HBCU in the nation designated as the location for
National Center for Bioethics in Research and Health Care.
Points of Distinction

6. Aerospace: experimental aerodynamics, vortex-dominated flows, flight
simulation, configuration aerodynamics, human interface.
Chemical: microfluidics, corrosion, carbon capture, bio-fuels, adsorption,
water & wastewater treatment, smart manufacturing, bio-chemical
engineering, chemical process modeling.
Electrical: electronic warfare and technology; systems engineering; control
systems, wireless sensors and data gathering networks, information
assurance; integrated circuits; cyber; power/energy.
Mechanical: fracture and fatigue evaluation, additive manufacturing, proton
and ion conductive membranes, corrosion and coatings, environmental
aging of materials, dislocation dynamics in materials, fuel cells.
Materials Science & Engineering: synthesis and chemical analysis of
materials, processing of bio materials, performance and nondestructive
evaluation, and modeling.
6
Core Strengths and Capabilities
College of Engineering

7. Degrees Offered by the College of Engineering
➢Bachelor of Science in Aerospace Science Engineering
➢Bachelor of Science in Chemical Engineering
➢Bachelor of Science in Electrical Engineering
➢Bachelor of Science in Mechanical Engineering
➢Master of Science in Chemical Engineering
➢Master of Science in Electrical Engineering
➢Master of Science in Electrical Engineering with concentration in
Systems Engineering
➢Master of Science in Materials Science and Engineering
➢Master of Science in Mechanical Engineering
➢Doctor of Philosophy in Materials Science and Engineering
7

8. Tuskegee University’s Centers of Excellence
Center for Biomedical
Research
(NIH-RCMI)
Directors : Drs. Yates & Samuel
National Center for Bioethics
in Research and Healthcare
(NIH)
Director : Dr. Rueben Warren
Center for Advanced
Materials (T-CAM)
Director : Dr. Shaik Jeelani
Center for Research
Excellence in Science and
Technology (NSF-CREST)
Director : Mahesh Hosur
Carver Integrative
Sustainability Center
Director : Dr. Raymon Shange
Tuskegee
University’s
Centers of Excellence
Carver Agricultural Experiment
Station (Land Grant-USDA)
Director : Dr. Walter Hill
Center of Information
Assurance Education (DHS)
Director : Dr. Hira Narang
TU Center for Academic
Excellence & Innovative
Learning (T-CAEL)
Director : Ms. Sherry King
NUCOR Education and
Research Center (NERC)
Director : Dr. Heshmat Aglan
Chevron - Additive
Manufacturing Center
Directors: Drs. Akasheh & Aglan

9. Nucor Education and Research Center of Excellence (NERC)
Focuses on industry based research in the latest trends in steel technologies
including dual phase microstructure, HSLAS, weathering and corrosion
resistance and high impact resistant steels, etc.
9

11. Railroad rail head repair
Date of Patent: June 17, 2016
Patent No. US 20140166766 A1
Assignee: Tuskegee University
ABSTRACT
A multi-pass gas metal arc weld (“GMAW”)
approach is used for in-situ repair of railhead
defects. A defect is removed via machining a
perpendicular slot or grove in the railhead leaving
the web and base unaltered. A sufficient number of
GMAW passes are used to fill the slot using a weld
material suitable for the particular type of parent
steel, and excess weldment can be removed.
Optionally, for pearlitic steel rails post-weld heat
treatment can be used to cause austenization and/or
quenching of the weld. The weld heat inputs and
other parameters are controlled to avoid ductile and
brittle fracture related morphologies.
Railroad Rail Head Repair
Gauge Corner Spalling

12. Nanostructured Thin Films and Coatings
Aluminum substrates without and
with nanostructured coatings
NANOSTRUCTURED
THERMOPLASTIC
POLYIMIDE FILMS
Date of Patent: May 19, 2015
Assignee: Tuskegee University
Proton Conductive Membrane
Sand-Jet Edge Erosion for Uncoated and
Coated Graphite Epoxy Composites

13. Challenging Pre-Engineering and Pipeline Programs
NAME OF SUMMER PROGRAM GRADE PERIOD
Freshman Accelerated Start-up
Training for Retention in Engineering
Curricula (FASTREC)
Pre-
freshman
12th Grade
Eight weeks
(8 College level credits)
(Boarding Program)
Minority Introduction to Engineering
(MITE)
11th Grade One week
(Boarding Program)
National Summer Transportation
Institute (NSTI)
9th &10th
Grade
Two weeks
(Day Camp)
Fly High Your Math & Science Skills 9th Grade One week
(Day Camp)
Camp Drone Zone 8th Grade One week
(Day Camp)
Research Experience for
Undergraduate (REU)
College
Sophomore
&Junior
Eight weeks
(Boarding Program)
13

14. The European Union’s Reduction of Hazardous
Substances
The European Union’s RoHS legislation banned the use of four
hazardous materials one of these materials was Lead. Lead is used in
solder alloys and is the connecting medium in electronic circuits

15. Aerospace, Defense & High Performance Electronics are
affected by this legislation

16. Aerospace, Defense and High Performance Electronics are
affected at the component level
Since the RoHS
legislation
Commercial
Component
terminations are
now plated with
Tin

17. Tin plating material has a long history of growing
Tin whiskers

18. What are Tin Whiskers?
Tin Whiskers are
electrically
conductive
single crystalline
tin structures
that grow from
tin-plated
surfaces

19. Tin Whiskers are very small

20. Components are getting smaller and the gap
between terminations is narrowing
Gap spacing
between the
electrical leads on
components is
decreasing

21. Tin Whiskers are closing the gap

22. What are Conformal Coatings and can they help?
Below is a conformal coated
circuit board
Above is a circuit board prior to
conformal coating

23. Tin Whiskers versus Conformal Coatings
Tin Whiskers
will grow
through
conformal
coatings, so
how can
conformal
coatings
help?

24. Growing out is easy growing in is more difficult
Once out it is
a long trip to
the other
termination.

25. Because of Tin Whiskers Bad things have
happened
Galaxy IV Satellite
Galaxy VII Satellite
Solidaridad 1 Satellite
Galaxy IIIR Satellite
Dominion Millstone
Duane Arnold
Dresden
South Texas Project
Nuclear Reactors
Toyota Accelerator
Heart Pacemaker
Recall
Patriot
Missile
Phoenix Missile
Aircraft Relay
Aircraft Radar

26. If Conformal coatings can protect circuits from
corrosion on Naval Vessels, can they prevent
circuits from shorts?
Tin plated brass coupons
coated with Epoxy,
Acrylic, Urethane and
silicon conformal coatings
are submerged in a salt
solution waiting for the
growth of Tin Whiskers

27. However to study Tin
Whiskers you we
must be able to find
them. Students at
Tuskegee start their
search with an
Optical Microscope
The search for Tin Whiskers

28. The students start their search for whiskers using
the Microscope and a grid
The Grid
A B C D
1234567
The Test Coupon

29. The they take the Coupon and examine the locations under
a Scanning Electron Microscope
The Hitachi S3400N
Scanning Electron
Microscope
Dr. Aglan and graduate students
examining a Tin Whisker

30. Tuskegee Students use a Scanning Electron Microscope
and XRD to confirm it is a Tin Whisker
SEM micrograph showing salt crystals on
acrylic coating from scratched flat coupon
after 9500 hour exposure to corrosive
environment (aqueous NaCl);
magnification is 400X (a); XRD is shown
on right (b). The percentages of tin and
oxygen are 4.38% and 11.08%,
respectively.
SEM micrograph showing conjoined
whiskers from scratched flat coupon after
7000 hours of exposure to corrosive
environment (aqueous NaCl);
magnification is 4000X. The percentages
of tin and oxygen are 56.34% and 34.61%
respectively.

31. With patience and a lot of searching students at Tuskegee
are growing and finding Tin Whiskers

32. Conformal Coated Coupons in a Thermal
Chamber
A coupon half covered with a
conformal coating and the other
half exposed.
Coupons going through a Thermal
Cycling process to accelerate the
growth of Tin Whiskers.

33. A coupon half covered with a conformal coating and the other half
exposed. Determining the effectiveness of the various conformal
coatings to inhibit the growth of Tin Whiskers
Conformal Coated Coupons in a Thermal
Chamber

34. Probability of a Tin Whisker Shorting
between two Adjacent Leads

35. David Burdick and graduate students reviewing
the progress and the next steps

36. The Next Steps
➢ The study to determine if one conformal coating is better at
mitigating the effects of corrosion is still on going.
➢ The study to calculate the probability of a Tin Whisker causing
a short is on going.
➢ The study to determine if one conformal coating it better at
mitigating the risk of a Tin Whisker short is on going.
➢ A new effort is being considered to improve the effectiveness of
preventing penetration of conformal coatings by Tin Whiskers
by using nanoparticles.
➢ A new project is being considered to studying the reliability of
various Pb-free solder alloys.

37. Questions?