Abstract

This paper presents a new design architecture for mechanically flexible light-emitting diode (LED) signage modules for applications in digital advertising on curved surfaces. The new design comprises an array of commonly used rigid printed circuit boards (PCBs) but of smaller size with some spacing between them, which is encapsulated by a flexible substrate or potting material, instead of a large single rigid PCB in the entire LED module as in the case of conventional LED signage modules. Commonly used through-hole type red-green-blue (RGB) LEDs are considered. To demonstrate the design, manufacturing, and mechanical flexibility of the design, a prototype LED signage module with a typical industry standard size of 304 mm × 304 mm × 10 mm was designed and fabricated. Experimental testing and finite element simulations were conducted to analyze mechanical flexibility and internal stresses in the module. The results demonstrate that the new design provides flexible LED modules, without altering the conventional LED control system. It is shown that maximum stress occurs in the spacing between the PCBs and is small even for large module deflection. As the curvature of module deflection was decreased, the maximum stress increased, indicating an important design parameter for the module deflection. The proposed design architecture will enable both indoor and outdoor digital advertising using billboards on a wide range of curved surfaces.

References

1.
Grobelny
,
J.
, and
Michalski
,
R.
,
2011
, “
Various Approaches to a Human Preference Analysis in a Digital Signage Display Design
,”
Hum. Factors Ergonom. Manuf. Serv. Ind.
,
21
(
6
), pp.
529
542
.10.1002/hfm.20295
2.
Ravnik
,
R.
, and
Solina
,
F.
,
2013
, “
Audience Measurement of Digital Signage: Quantitative Study in Real-World Environment Using Computer Vision
,”
Interact. Comput.
,
25
(
3
), pp.
218
228
.10.1093/iwc/iws023
3.
Dennis
,
C.
,
Newman
,
A.
,
Michon
,
R.
,
Brakus
,
J. J.
, and
Wright
,
L. T.
,
2010
, “
The Mediating Effects of Perception and Emotion: Digital Signage in Mall Atmospherics
,”
J. Retailing Consum. Serv.
,
17
(
3
), pp.
205
215
.10.1016/j.jretconser.2010.03.009
4.
Bauer
,
C.
, and
Strauss
,
C.
,
2016
, “
Location-Based Advertising on Mobile Devices
,”
Manage. Rev. Q.
,
66
(
3
), pp.
159
194
.10.1007/s11301-015-0118-z
5.
Bauer
,
C.
,
Dohmen
,
P.
, and
Strauss
,
C.
,
2011
, “
Interactive Digital Signage-an Innovative Service and Its Future Strategies
,”
International Conference on Emerging Intelligent Data and Web Technologies
, Tirana, Albania, Sept. 7–9, pp.
137
142
.10.1109/EIDWT.2011.29
6.
Cope
,
R. C.
,
2015
, “Flexible Display,” U.S. Patent No. 9,013,367.
7.
Chu
,
S. C. K.
,
Fatt
,
C. T.
, and
Ling
,
O. S.
,
2014
, “LED Module Design,” U.S. Patent No. 8,721,119.
8.
Quadri
,
P.
, and
Cavenati
,
A.
,
2012
, “LED Screen,” U.S. Patent Application No. 13/228,125.
9.
Tanaka
,
I.
,
Uchida
,
A.
, and
Irie
,
T.
,
1990
, “Sheet Type Large Display Unit,” U.S. Patent No. 4,970,812.
10.
Goodrich
,
F. S.
,
1992
, “Flexible Incasements for LED Display Panels,” U.S. Patent No. 5,162,696.
11.
Martin
,
J. D.
, and
Smith
,
A. W.
,
2013
, “Reinforced Housing Structure for a Lighted Sign or Lighting Fixture,” U.S. Patent No. 8,449,142.
12.
Chen
,
B.
,
Zhou
,
S.
,
Cheng
,
X.
,
Zhang
,
B.
, and
Li
,
S.
,
2008
, “
Luminous Sign With Encapsulated Led Chips
,” U.S. Patent Application No. 11,852,209.
13.
Thompson
,
C.
,
McFerrin
,
D. C.
,
Counts
,
J.
,
Morgan
,
P.
, and
Thomas
,
T. J.
,
2006
, “
LED Signage Device
,” U.S. Patent No. 7,086,769.
14.
Stoll
,
A.
, and
Von Zittwitz
,
P.
,
2013
, “LED Assembly for a Signage Illumination,” U.S. Patent No. 8,610,357.
15.
Meguid
,
S. A.
,
Zhuo
,
C.
, and
Yang
,
F.
,
2014
, “
Effective Mitigation of Shock Loads in Embedded Electronic Packaging Using Bilayered Potting Materials
,”
ASME J. Electron. Packag.
,
136
(
4
), p.
041010
.10.1115/1.4026542
16.
Nunziato
,
J. W.
, and
Schuler
,
K. W.
,
1973
, “
Shock Pulse Attenuation in a Nonlinear Viscoelastic Solid
,”
J. Mech. Phys. Solids
,
21
(
6
), pp.
447
457
.10.1016/0022-5096(73)90012-4
17.
Ardebili
,
H.
,
Zhang
,
J.
, and
Pecht
,
M.
,
2018
,
Encapsulation Technologies for Electronic Applications
,
William Andrew
, Cambridge, MA, pp.
57
59
.
18.
Wang
,
H.
,
Zhou
,
H.
,
Zhang
,
Y.
, and
Li
,
D.
,.”
2010
, “
Stabilized Filling Simulation of Microchip Encapsulation Process
,”
Microelectron. Eng.
,
87
(
12
), pp.
2602
2609
.10.1016/j.mee.2010.07.026
19.
Haynes
,
A. S.
,
Cordes
,
J. A.
, and
Krug
,
J.
, ”
2013
, “
Thermomechanical Impact of Polyurethane Potting on Gun Launched Electronics
,”
J. Eng.
,
2013
, pp.
1
11
.10.1155/2013/148362
20.
Moore
,
L.
, and
Barrett
,
J.
,
2012
, “
Board-Folding Method for Fabrication of 3-D System in Package Devices
,”
IEEE Trans. Compon., Packag. Manuf. Technol.
,
2
(
7
), pp.
1209
1216
.10.1109/TCPMT.2012.2196042
21.
Luo
,
X.
,
Hu
,
R.
,
Liu
,
S.
, and
Wang
,
K.
,
2016
, “
Heat and Fluid Flow in High-Power LED Packaging and Applications
,”
Prog. Energy Combust. Sci.
,
56
, pp.
1
32
.10.1016/j.pecs.2016.05.003
22.
Frear
,
D.
,
2017
, “
Packaging Materials
,”
Springer Handbook of Electronic and Photonic Materials
,
Springer
,
Cham, Switzerland
.
23.
Norris
,
A. W.
,
Bahadur
,
M.
, and
Yoshitake
,
M.
,
2005
, “
Novel Silicone Materials for LED Packaging
,”
Fifth International Conference on Solid State Lighting
, Vol.
5941
, San Diego, CA, July 31–Aug. 4, p.
594115
.10.1117/12.617250
24.
Pecht
,
M.
, and
Nguyen
,
L. T.
,
1995
,
Plastic-Encapsulated Microelectronics: Materials, Processes, Quality, Reliability, and Applications
, Wiley, New York, pp.
269
282
.
25.
Singh
,
P.
, and
Viswanadham
,
P.
,
2012
,
Failure Modes and Mechanisms in Electronic Packages
,
Springer Science & Business Media
, Berlin.
26.
Chao
,
N. H.
,
Cordes
,
J. A.
,
Carlucci
,
D.
,
DeAngelis
,
M. E.
, and
Lee
,
J.
,
2011
, “
The Use of Potting Materials for Electronic-Packaging Survivability in Smart Munitions
,”
ASME J. Electron. Packag.
,
133
(
4
), p.
041003
.10.1115/1.4005375
27.
Cheng
,
T.
,
Luo
,
X.
,
Huang
,
S.
, and
Liu
,
S.
,
2010
, “
Thermal Analysis and Optimization of Multiple LED Packaging Based on a General Analytical Solution
,”
Int. J. Therm. Sci.
,
49
(
1
), pp.
196
201
.10.1016/j.ijthermalsci.2009.07.010
28.
Yu
,
X.
,
Shu
,
W.
,
Hu
,
R.
,
Xie
,
B.
,
Ma
,
Y.
, and
Luo
,
X.
,
2017
, “
Dynamic Phosphor Sedimentation Effect on the Optical Performance of White LEDs
,”
IEEE Photonics Technol. Lett.
,
29
(
14
), pp.
1195
1198
.10.1109/LPT.2017.2712280
29.
Hu
,
R.
,
Iwamoto
,
S.
,
Feng
,
L.
,
Ju
,
S.
,
Hu
,
S.
,
Ohnishi
,
M.
,
Nagai
,
N.
,
Hirakawa
,
K.
, and
Shiomi
,
J.
,
2020
, “
Machine-Learning-Optimized Aperiodic Superlattice Minimizes Coherent Phonon Heat Conduction
,”
Phys. Rev. X
,
10
(
2
), p.
021050
.10.1103/PhysRevX.10.021050
30.
Hu
,
R.
,
Liu
,
Y.
,
Shin
,
S.
,
Huang
,
S.
,
Ren
,
X.
,
Shu
,
W.
,
Cheng
,
J.
,
Tao
,
G.
,
Xu
,
W.
,
Chen
,
R.
, and
Luo
,
X.
,
2020
, “
Emerging Materials and Strategies for Personal Thermal Management
,”
Adv. Energy Mater.
,
10
(
17
), p.
1903921
.10.1002/aenm.201903921
31.
Leissa
,
A. W.
, and
Niedenfuhr
,
F. W.
,
1962
, “
A Study of the Cantilevered Square Plate Subjected to a Uniform Loading
,”
J. Aerosp. Sci.
,
29
(
2
), pp.
162
169
.10.2514/8.9357
32.
Callister
,
W. D.
, and
Rethwisch
,
D. G.
,
2007
,
Materials Science and Engineering: An Introduction
, Vol.
7
,
John Wiley & Sons
,
New York
.
33.
Epic Resins
, 2019, “RM2018—Technical Datasheet,” Epic Resins, Palmyra, PA.
34.
Cree
,
2019
, “
Product Family Data Sheet—Cree® Screen Master® 4-mm Oval LEDS4SMS
,”
Cree
, Durham, NC.
35.
Wu
,
C. H.
, and
Chuang
,
H. J.
,
2000
, “LED Power Supply with Temperature Compensation,” U.S. Patent No. 6,111,739.
36.
Grajcar
,
Z.
,
2011
, “Apparatus and Methods for the Thermal Regulation of Light Emitting Diodes in Signage,” U.S. Patent No. 7,948,190.
37.
Yao
,
Y.
,
Lu
,
G. Q.
,
Boroyevich
,
D.
, and
Ngo
,
K. D.
,
2015
, “
Survey of High-Temperature Polymeric Encapsulants for Power Electronics Packaging
,”
IEEE Trans. Compon., Packag. Manuf. Technol.
,
5
(
2
), pp.
168
181
.10.1109/TCPMT.2014.2337300
38.
ANSYS,
2018
, “
ANSYS® Academic Research—Mechanical, Release 18.1
,”
ANSYS
, Canonsburg, PA.
39.
Mills
,
N. J.
, and
Gilchrist
,
A.
,
2000
, “
Modelling the Indentation of Low Density Polymer Foams
,”
Cell. Polym.
,
19
(
6
), pp.
389
412
.http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=877284
40.
Ogden
,
R. W.
,
1972
, “
Large Deformation Isotropic Elasticity-on the Correlation of Theory and Experiment for Incompressible Rubberlike Solids
,”
Proc. R. Soc. London. A.
,
326
(
1567
), pp.
565
584
.10.1098/rspa.1972.0026
41.
Hill
,
R.
,
1979
, “
Aspects of Invariance in Solid Mechanics
,”
Advances in Applied Mechanics
, Vol.
18
,
Elsevier
, pp.
1
75
.
42.
Widdle
,
R. D.
, Jr.
,
2005
, “
Measurement and Modeling of the Mechanical Properties of Polyurethane Foam
,”
Ph.D. thesis
,
Purdue University
, West Lafayette, IN.https://www.researchgate.net/publication/27233895_Measurement_and_modeling_of_the_mechanical_properties_of_flexible_polyurethane_foam
43.
Widdle
,
R. D.
, Jr.
,
Bajaj
,
A. K.
, and
Davies
,
P.
,
2008
, “
Measurement of the Poisson's Ratio of Flexible Polyurethane Foam and Its Influence on a Uniaxial Compression Model
,”
Int. J. Eng. Sci.
,
46
(
1
), pp.
31
49
.10.1016/j.ijengsci.2007.09.002
44.
Cook
,
R. D.
,
2007
,
Concepts and Applications of Finite Element Analysis
,
Wiley
, New York.
45.
ANSYS, Inc.
, 2019, “
Academic Research Mechanical, Release 18.1, Help System, Finite Element Analysis Guide
,”
ANSYS
, Canonsburg, PA.
46.
Li
,
M.
,
Tudor
,
J.
,
Liu
,
J.
,
Torah
,
R.
,
Komolafe
,
A.
, and
Beeby
,
S.
,
2019
, “
Novel Electronic Packaging Method for Functional Electronic Textiles
,”
IEEE Trans. Compon., Packag. Manuf. Technol.
,
9
(
2
), pp.
216
225
.10.1109/TCPMT.2019.2892404
47.
M.
Szycher
, ed.,
2012
,
Szycher's Handbook of Polyurethanes
,
CRC Press
, Boca Raton, FL.
48.
Wang
,
Y. Q.
,
Low
,
K. H.
,
Che
,
F. X.
,
Pang
,
H. L. J.
, and
Yeo
,
S. P.
,
2003
, “
Modeling and Simulation of Printed Circuit Board Drop Test
,” Proceedings of the Fifth Electronics Packaging Technology Conference (
EPTC 2003
), Singapore, Dec. 12, pp.
263
268
.10.1109/EPTC.2003.1271526
You do not currently have access to this content.