hbcu presentation
TRANSCRIPT
A Research Effort to Evaluate the Effectiveness of Conformal Coatings
and to Determine the Probability of Tin Whisker Induced Shorts
By Dr. H. Aglan, Tuskegee University
David Burdick, The Boeing Co.
The Calling of Education at Tuskegee: a holistic approach for performance-ready talent:
� HEAD - requisite knowledge for one’s field (Competence)
� HANDS - ready and willing to translate into practical experience within a specified field (Capability)
� HEART - personal sense of passion and integrity toward one’s work (Character)
Our Philosophy
3
Tuskegee University Overview
¾Independent and state-related institution of higher education ¾The academic programs are organized into five colleges and two schools ¾The 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. ¾Tuskegee enrolls more than 3,000 students and employs approximately 900 faculty and support personnel. ¾Physical facilities include more than 5,000 acres of forestry and a campus on which sits more than 100 major buildings and structures.
Aerospace: experimental aerodynamics, vortex-dominated flows, flight simulation, configuration aerodynamics, human interface.
Chemical: bio-fluidics, corrosion, carbon capture, bio-fuels, electrochemical catalysis, environmental, water & wastewater, nuclear reactor materials, 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, 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/manufacturing of bio materials, performance and nondestructive evaluation, and modeling.
College of Engineering-Core Strengths & Capabilities
5
Summary of College of Engineering-Highlights
¾Number of students: ~650 undergraduate and ~50 graduate ¾ Number of Faculty: 35 ¾Annual Research Awards: ~ $ 12 M
CE 2014-2015 Publications
Departments AE Ch.E EE MSEG ME Refereed
Publications 8 17 10 25 25 85 Book Chapters 0 0 0 2 0 2 Non -Refereed 1 0 2 21 2 26
National Conferences 5 11 4 36 9 65
International Conf. 0 3 10 23 4 40 Total 14 31 26 107 40 218
Additive Manufacturing
� Tuskegee is a member of the Institute for Advanced Composite Manufacturing Innovation (IACMI), a consortium consisting of Oak Ridge National Lab, UTK, Industrial and Academic Institutions.
� Tuskegee 3D Printing Research and Educational Facilities: ¾ 3D printing of antimicrobial packaging films and tissue
scaffolds ¾ Developing of polymeric based filaments with various nano
and micro additives for 3D printing ¾ Tuskegee/Chevron Additive Manufacturing Laboratory (part
design, 3D scanning and reverse engineering, functional models)
8
3D printing head with polymer solution
3D printed anti microbial films with silver nanoparticles for wound healing
3D film Printing for Biomedical Applications
9
Fatigue Crack Propagation Kinetics of Bainitic and Pearlitic Rail Steels
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
0 10 20 30 40 50 60 70Energy Release rate, J* (kJ/m2)
Cra
ck G
row
th r
ate,
da/
dN
(m/c
ycle
)
Bainitic Pearlitic
Fatigue crack propagation kinetics correlation with fracture surface morphology, fast crack region
bainitic
pearlitic
Hypervelocity Impact Analysis of Aerospace Materials
Aluminum Alloy Phenolic Resin Silicon Carbide
Plasma Drag Hypervelocity
Particle Accelerator
Nanostructured Polymeric and Cementitious Materials
Dispersion of Nanoparticles
Well dispersed Acid treated MWCNTs
Mechanical Performance of Nanostructured MWCNT Tetrafunctional Epoxy Systems
020
406080
100120140160
180200
0 0.2 0.4 0.6 0.8 1 1.2Deflection, mm
Fle
xura
l Str
ess,
MP
a
nano
neat
MWCNT dispersed in epoxy matrix A considerable enhancement in the
flexural strength has been achieved with MWCNT reinforcement.
Testing and evaluation of Materials and Components under Extreme Conditions
¾Salt fog &SO2 exposure ¾Salt fog ¾Sand cloud exposure ¾UV aging ¾A combination of the above tests
The European Union’s RoHS (Reduction of Hazardous Substances) legislation banned the use of four hazardous materials one of these materials was Lead. Lead is used in solder alloys
Aerospace, Defense and High Performance Electronics are affected at the component level
Since the RoHS legislation Component terminations are now plated with Tin
Tin Whiskers are electrically conductive single crystalline tin structures that grow from pure tin-plated surfaces
What are Tin Whiskers?
Components are getting smaller and the gap between terminations
is narrowing
Gap spacing is decreasing
So what are the implications when they close the gaps?
Galaxy IV Satellite Failure
What are Conformal Coatings and can they help
Below is a conformal coated circuit board
Above is a circuit board prior to conformal coating
Conformal coatings protect circuits from corrosion on Naval
Vessels
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
The search for Tin Whiskers
The Olympus G5000 Optical Microscope
Students at Tuskegee start the search with an Optical Microscope
The students start their search for whiskers using the Microscope and a
grid
The Test Coupon The Grid
A B C D
1
2
3
4
5
6
7
The they take the Coupon and examine the locations under a Scanning Electron Microscope
Dr. Aglan and graduate students examining a Tin Whisker growth
The Hitachi S3400N Scanning Electron
Microscope
Tuskegee Students uses 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.
Conformal Coated Coupons in a Thermal Chamber
Coupons going through a Thermal
Cycling process to accelerate the
growth of Tin Whiskers.
A coupon half covered with a
conformal coating and the other
half exposed.
Conformal Coated Coupons in a Thermal Chamber
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
The Next Steps ¾ The study to determine if one conformal coating is better at
mitigating the effects of corrosion is still underway.
¾ The study to calculate the probability of a Tin Whisker causing
a short is still underway.
¾ The study to determine if one conformal coating it better at
mitigating the risk of a Tin Whisker short is still underway.
¾ A new effort is being considered to improve the effectiveness
of preventing penetration of conformal coatings by Tin
Whiskers by using nanoparticles.