A brittle thin film bonded to a substrate is common in MEMS components. At the edge of the interface, high stress gradients exist. It has been observed that mechanical strengthening of the thin film with decreasing film size occurs due to two constraints, namely, the microstructural constraint and the geometrical constraint. Consideration of both these constraints is required to properly predict the size effect impact on the strength of a brittle thin film. In this paper, a statistical approach is developed to predict the size effect of a brittle thin film on a substrate.

1.
Andersens
J., J.
,
2005
, “
Advanced fragmentation stage of oxide coating on polymer substrate under biaxial tension
,”
Thin Solid Films
,
471
(
1)
, pp.
209
217
.
2.
Wisnom
M. R.
,
1999
, “
Size effects in the testing of fibre-composite materials
,”
Compos. Sci. Technol.
,
59
(
13)
, pp.
1937
1957
.
3.
Haque
M. A.
, and
Saif
M. T. A.
,
2003
, “
Strain gradient effect in nanoscale thin films
,”
Acta Materialia
,
51
(
11)
, pp.
3053
3061
.
4.
Arzt
E.
,
1998
, “
Size effects in materials due to microstructural and dimensional constraints: A comparative review
,”
Acta Materialia
,
46
(
16)
, pp.
5611
5626
.
5.
Tsuchiya
T.
,
Tabata
O.
,
Sakata
J.
, and
Taga
Y.
,
1998
, “
Specimen size effect of tensile strength of surface- micromachined polycrystalline silicon thin films
,”
J. Microelectromech. Syst.
,
7
(
1)
, pp.
106
113
.
6.
Pugno, N.M., and Ruoff, R.S., 2006, “Nanoscale weibull statistics,” J. Appl. Phys., 99(2).
7.
Morquio, A.A., and Riera, J.D., 2003, “Size and strain rate effects in the mechanical properties of materials,” 17th International Conference on Structural Mechanics in Reactor Technology, Prague, Czech Republic, August 17–22.
8.
Bru¨ckner-Foit, A., Hu¨lsmeier, P., Sckuhr, M., and Riesch-Oppermann, H., 2000, “Limitations of the weibull theory in stress fields with pronounced stress gradients,” Proceedings of ASME Turbo Expo, Munich, Germany, pp. 1–5.
9.
Xiang
Y.
,
Chen
X.
, and
Vlassak
J. J.
,
2005
, “
Plane-strain bulge test for thin films
,”
Journal of Materials Research
,
20
(
9)
, pp.
2360
2370
.
10.
Goyal
A.
,
Cheong
J.
, and
Tadigadapa
S.
,
2004
, “
Tin-based solder bonding for mems fabrication and packaging applications
,”
J. Micromech. Microeng.
,
14
(
6)
, pp.
819
825
.
11.
Ko¨hler
J.
,
Jonsson
K.
,
Greek
S.
, and
Stenmark
L.
,
2000
, “
Weibull fracture probability for silicon wafer bond evaluation
,”
J. Electrochem. Soc.
,
147
(
12)
, pp.
4683
4687
.
12.
Fett
T.
,
Ernst
E.
,
Munz
D.
,
Badenheim
D.
, and
Oberacker
R.
,
2003
, “
Weibull analysis of ceramics under high stress gradients
,”
J. Eur. Ceram. Soc.
,
23
(
12)
, pp.
2031
2037
.
13.
Fett
T.
,
1996
, “
Weight functions for cracks at sharp notches and notch intensity factors
,”
Int. J. Fracture
,
77
(
2)
, pp.
R27–R33
R27–R33
.
14.
Fett, T., and Munz, D., 1997, Stress intensity factors and weight functions, Computational Mechanics Publications, Southampton, UK.
15.
Ekwaro-Osire, S., Khandaker, M., and Gautam, K., 2006, “Accounting for high stress gradient by a modified weibull failure theory,” submitted to Journal of Engineering Materials and Technology - Transactions of the ASME.
16.
Gleich
D. M.
,
Van Tooren
M. J. L.
, and
Beukers
A.
,
2001
, “
A stress singularity approach to failure initiation in a bonded joint with varying bondline thickness
,”
J. Adhes. Sci. Technol.
,
15
(
10)
, pp.
1247
1259
.
17.
Akisanya
A. R.
,
1997
, “
On the singular stress field near the edge of bonded joints
,”
J. Strain Anal. Eng.
Des.,
32
(
4)
, pp.
301
311
.
18.
Bru¨ckner-Foit, A., Diegele, E., Hulsmeier, P., Rettig, U., and Hohmann, C., 2002, “Prediction of the failure probability of high strength ceramics subject to thermal shock loading,” 26th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A, Jan 13–18 2002, Cocoa Beach, FL, 23, pp. 141–148.
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