In the design of printed circuit boards (PCBs), it is preferable to increase their fundamental frequency so as to reduce the effects of the dynamic loading on them. The dynamic characteristics of a PCB carrying various electronic components and modules are most significantly affected by the geometrical and material properties of the bare board and by the boundary conditions supporting the loaded PCB. In this research, a PCB carrying a heavy CPU cooling fan and supported by six fastening screws is investigated by the modal testing and analyzed by the finite element method. After the finite element model of the PCB is verified by the experimental results, the locations of the six supporting screws are optimized to achieve a maximum fundamental frequency for the loaded PCB. The position of each fastening screw can be determined by two design variables, i.e., x and y coordinates. Two cases are studied: the symmetric case (six design parameters) with the symmetric constraint on the support locations imposed, and the asymmetric case (12 design parameters) without the constraint imposed. Finally, verification experiments are performed on the two PCBs supported by screws located at the optimal positions. Although relatively large differences between the calculated, optimized fundamental frequencies and the experimental values are observed, the experiments confirm a very significant improvement in frequency for both cases.

1.
Barker
,
D. B.
, and
Chen
,
Y. S.
, 1993, “
Modeling the Vibration Restraints of Wedge Lock Card Guides
,”
ASME J. Electron. Packag.
1043-7398,
115
, pp.
189
194
.
2.
Pitarresi
,
J. M.
, and
Di Edwardo
,
A. V.
, 1993, “
A Design Approach for the Systematic Improvement of Support Locations for Vibrating Circuit Cards
,”
ASME J. Electron. Packag.
1043-7398,
115
, pp.
118
123
.
3.
Suhir
,
E.
, 2000, “
Predicted Fundamental Vibration Frequency of a Heavy Electronic Component Mounted on a Printed Circuit Board
,”
ASME J. Electron. Packag.
1043-7398,
122
, pp.
3
5
.
4.
Pitarresi
,
J. M.
,
Caletka
,
D. V.
,
Galdwell
,
R.
, and
Smith
,
D. E.
, 1991, “
The Smeared Property Technique for the FE Vibration Analysis of Printed Circuit Cards
,”
ASME J. Electron. Packag.
1043-7398,
113
, pp.
250
257
.
5.
Pitarresi
,
J. M.
, and
Primavera
,
A. A.
, 1992, “
Comparison of Modeling Techniques for the Vibration Analysis of Printed Circuit Cards
,”
ASME J. Electron. Packag.
1043-7398,
114
, pp.
378
383
.
6.
Ong
,
J. H.
, and
Lim
,
G. H.
, 2000, “
A Simple Technique for Maximizing the Fundamental Frequency of Vibrating Structures
,”
ASME J. Electron. Packag.
1043-7398,
122
, pp.
341
349
.
7.
Ong
,
J. H.
, and
Lim
,
G. H.
, 1999, “
Dynamic Finite Element Model Improvement of a PCB Structure
,”
J. Vib. Control
1077-5463,
5
, pp.
57
74
.
8.
Pitarresi
,
J.
,
Geng
,
P.
,
Beltman
,
W.
, and
Ling
,
Y.
, 2002, “
Dynamic Modeling and Measurement of Personal Computer Motherboards
,”
Proceedings of the 2002 Electronic Components and Technology Conference
,
San Diego
, CA, May 28–31, pp.
597
603
.
9.
Pitarresi
,
J.
,
Roggeman
,
B.
,
Chaparala
,
S.
, and
Geng
,
P.
, 2004, “
Mechanical Shock Testing and Modeling of PC Motherboards
,”
Proceedings of the 2004 Electronic Components and Technology Conference
, Las Vegas, NV, June 1–4, pp.
1047
1054
.
10.
Friswell
,
M. I.
, and
Mottershead
,
J. E.
, 1995,
Finite Element Model Updating in Structural Dynamics
,
Kluwer
, Dordrecht, pp.
1
4
.
11.
Sinha
,
J. K.
, and
Friswell
,
M. I.
, 2002, “
Model Updating: A Tool for Reliable Modeling, Design Modification and Diagnosis
,”
Shock Vib. Dig.
0583-1024,
34
(
1
), pp.
27
35
.
12.
Chen
,
K.-N.
, and
Cheng
,
H.-C.
, 2004, “
Identification of Equivalent Material Constants of a Printed Circuit Board
,”
Proceedings of the 2004 International Conference on Computational & Experimental Engineering & Sciences, ICCES04
,
Madeira, Portugal
, July 26–29,
S. N.
Atluri
et al.
, eds.,
Tech Science
, Forsyth, GA, pp.
1114
1119
.
13.
Chen
,
K.-N.
, and
Cheng
,
H.-C.
, 2005, “
Simulation and Experimental Validation for the Dynamic Characteristics of Printed Circuit Boards
,”
Proceedings of IMAPS Taiwan 2005 International Technical Symposium
, IMAPS Taiwan, Taipei, June 23–25, pp.
294
298
.
14.
ANSYS Inc.
, 2002, “
ANSYS 7.0 Documentation
,” ANSYS Inc., Canonsburg, PA.
15.
Ewins
,
D. J.
, 2000,
Modal Testing: Theory, Practice and Application
,
2nd ed.
,
Research Studies
, Hertfordshire, UK.
You do not currently have access to this content.