Reliability of conformal coatings used to mitigate tin whisker growth depends on their ability to contain tin whiskers. Two key material properties required to assess the reliability of a polyurethane coating are documented experimentally: adhesion strength and puncture strength. A modified blister test using a predefined blister area is employed to assess the adhesion strength and a puncture test is employed to evaluate the puncture strength of the coating. After measuring the properties at time zero, the coatings are subjected to accelerated testing conditions (high temperature/humidity storage and temperature cycling) and the degradations of the coating properties are documented.

Issue Section:
Research Papers
Keywords:
tin whisker, conformal coating, blister test, puncture test, adhesion strength, puncture strength, polyurethane coating, accelerated testing
Topics:
Adhesion, Coating processes, Coatings, Testing, Urethane elastomers, Pressure

References

1.
Compton
,
K.
,
Mendizza
,
A.
, and
Arnold
,
S.
,
1951
, “
Filamentary Growths on Metal Surfaces—Whiskers
,”
Corrosion
,
7
(
10
), pp.
327
–
334
.
Google Scholar
Crossref
Search ADS
 
2.
Schroeder
,
V.
,
Bush
,
P.
,
Williams
,
M.
,
Vo
,
N.
, and
Reynolds
,
H. L.
,
2006
, “
Tin Whisker Test Method Development
,”
IEEE Trans. Electron. Packag. Manuf.
,
29
(
4
), pp.
231
–
238
.10.1109/TEPM.2006.887397
Google Scholar
Crossref
Search ADS
 
3.
Galyon
,
G. T.
,
2005
, “
Annotated Tin Whisker Bibliography and Anthology
,”
IEEE Trans. Electron. Packag. Manuf.
,
28
(
1
), pp.
94
–
122
.10.1109/TEPM.2005.847440
Google Scholar
Crossref
Search ADS
 
4.
Osterman
,
M.
,
2002
, “
Mitigation Strategies for Tin Whiskers
,” CALCE EPSC, College Park, MD, http://www.calce.umd.edu/lead-free/tin-whiskers/TINWHISKERMITIGATION.pdf
5.
Fox
,
W.
, and
Woody
,
L.
,
2010
, “
Conformal Coatings for Tin Whisker Risk Management
,”
IPC APEX EXPO Technical Conference
,
Las Vegas, NV, April 6–9
, pp.
890
–
920
.
6.
Kadesch
,
J. S.
, and
Leidecker
,
H.
,
2000
, “
Effects of Conformal Coat on Tin Whisker Growth
,”
37th IMAPS Nordic Annual Conference
, Helsingor, Finland, September 10–13, Paper No. S31-01, pp.
108
–
116
.
7.
Kadesch
,
J. S.
, and
Brusse
,
J.
,
2001
, “
The Continuing Dangers of Tin Whiskers and Attempts to Control Them With Conformal Coating
,” NASA EEE Links Newsletter, July.
8.
Woodrow
,
T. A.
, and
Ledbury
,
E. A.
,
2005
, “
Evaluation of Conformal Coatings as a Tin Whisker Mitigation Strategy
,”
IPC/JEDEC 8th International Conference on Lead-Free Electronic Components and Assemblies
,
San Jose, CA
, April 18–20.
9.
Woodrow
,
T. A.
, and
Ledbury
,
E. A.
,
2006
, “
Evaluation of Conformal Coatings as a Tin Whisker Mitigation Strategy, Part 2
,”
SMTA International Conference
,
Rosemont, IL
, September 24–28.
10.
Gent
,
A. N.
, and
Lewandowski
,
L. H.
,
1987
, “
Blow-Off Pressures for Adhering Layers
,”
J. Appl. Polym. Sci.
,
33
(
5
), pp.
1567
–
1577
.10.1002/app.1987.070330512
Google Scholar
Crossref
Search ADS
 
11.
Shirani
,
A.
, and
Liechti
,
K.
,
1998
, “
A Calibrated Frature Process Zone Model for Thin Film Blistering
,”
Int. J. Fract.
,
93
(
1
), pp.
281
–
314
.10.1023/A:1007548519223
Google Scholar
Crossref
Search ADS
 
12.
Dannenberg
,
H.
,
1961
, “
Measurement of Adhesion by a Blister Method
,”
J. Appl. Polym. Sci.
,
5
(
14
), pp.
125
–
134
.10.1002/app.1961.070051401
Google Scholar
Crossref
Search ADS
 
13.
Williams
,
M.
,
1969
, “
The Continuum Interpretation for Fracture and Adhesion
,”
J. Appl. Polym. Sci.
,
13
(
1
), pp.
29
–
40
.10.1002/app.1969.070130105
Google Scholar
Crossref
Search ADS
 
14.
Fernando
,
M.
, and
Kinloch
,
A.
,
1990
, “
Use of the ‘Inverted-Blister’ Test to Study the Adhesion of Photopolymers
,”
Int. J. Adhes. Adhes.
,
10
(
2
), pp.
69
–
76
.10.1016/0143-7496(90)90145-N
Google Scholar
Crossref
Search ADS
 
15.
Hinkley
,
J. A.
,
1983
, “
A Blister Test for Adhesion of Polymer Films to SiO2
,”
J. Adhes.
,
16
(2), pp.
115
–
126
.10.1080/00218468308074909
Google Scholar
Crossref
Search ADS
 
16.
Hencky
,
H.
,
1915
, “
Über den Spannungszustand in Kreisunden Platten mit Verschwindende
Biegungssteifigkeit,”
Z. Angew. Math. Phys.
,
63
, pp.
311
–
317
.
17.
Anderson
,
T. L.
,
2005
,
Fracture Mechanics: Fundamentals and Applications
,
Taylor & Francis Group
,
Boca Raton
, FL.
18.
Mahan
,
K.
,
Sun
,
Y.
,
Han
,
B.
,
Han
,
S.
, and
Osterman
,
M.
,
2011
, “
PoF Model of Conformal Coating Against Tin Whisker Growth: Performance Evaluation Under Operating and Storage Conditions
,” Center for Advanced Life Cycle Engineering (CALCE), College Park, MD, Paper No. C11-06.
19.
Nguyen
,
C.
, and
Vu-Khanh
,
T.
,
2004
, “
Mechanics and Mechanisms of Puncture of Elastomer Membranes
,”
J. Mater. Sci.
,
39
(
24
), pp.
7361
–
7364
.10.1023/B:JMSC.0000048751.55710.44
Google Scholar
Crossref
Search ADS
 
20.
JESD201
,
2006
,
“Environmental Acceptance Requirements for Tin Whisker Susceptibility of Tin and Tin Alloy Surface Finishes
,”
JEDEC Solid State Technology Association
,
Arlington, VA, JEDEC Standard No. 201
.
21.
IPC Cleaning and Coating Committee
,
2008
, “
Qualification and Performance of Electrical Insulating Compound for Printed Wiring Assemblies
,” IPC Association Connecting Electronics Industries, Bannockburn, IL, Report No. IPC-CC-830B.
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