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Using self-assembling monolayers to study crack initiation in epoxy/silicon joints

Published online by Cambridge University Press:  03 March 2011

M.S. Kent ,
E.D. Reedy ,
H. Yim ,
A. Matheson ,
J. Sorenson ,
J. Hall ,
K. Schubert ,
D. Tallant ,
M. Garcia  and
T. Ohlhausen
...Show all authors
M.S. Kent*
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
E.D. Reedy
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
H. Yim
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
A. Matheson
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
J. Sorenson
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
J. Hall
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
K. Schubert
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
D. Tallant
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
M. Garcia
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
T. Ohlhausen
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
R. Assink
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

The effect of the density and in-plane distribution of interfacial interactions on crack initiation in an epoxy-silicon joint was studied in nominally pure shear loading. Well-defined combinations of strong (specific) and weak (nonspecific) interactions were created using self-assembling monolayers. The in-plane distribution of strong and weak interactions was varied by employing two deposition methods: depositing mixtures of molecules with different terminal groups resulting in a nominally random distribution, and depositing methyl-terminated molecules in domains defined lithographically with the remaining area interacting through strong acid-base interactions. The two distributions lead to very different fracture behavior. For the case of the methyl-terminated domains (50 μm on a side) fabricated lithographically, the joint shear strength varies almost linearly with the area fraction of strongly interacting sites. From this we infer that cracks nucleate on or near the interface over nearly the entire range of bonded area fraction and do so at nearly the same value of local stress (load/bonded area). We postulate that the imposed heterogeneity in interfacial interactions results in heterogeneous stress and strain fields within the epoxy in close proximity to the interface. Simply, the bonded areas carry load while the methyl terminated domains carry negligible load. Stress is amplified adjacent to the well-bonded regions (and reduced adjacent to the poorly bonded regions), and this leads to crack initiation by plastic deformation and chain scission within the epoxy near the interface. For the case of mixed monolayers, the dependence is entirely different. At low areal density of strongly interacting sites, the joint shear strength is below the detection limit of our transducer for a significant range of mixed monolayer composition. With increasing density of strongly interacting sites, a sharp increase in joint shear strength occurs at a methyl terminated area fraction of roughly 0.90. We postulate that this coincides with the onset of yielding in the epoxy. For methyl-terminated area fractions less than 0.85, the joint shear strength becomes independent of the interfacial interactions. This indicates that fracture no longer initiates on the interface but away from the interface by a competing mechanism, likely plastic deformation and chain scission within the bulk epoxy. The data demonstrate that the in-plane distribution of interaction sites alone can affect the location of crack nucleation and the far-field stress required.

Keywords

PolymerAdhesionFracture
Type
Articles
Information
Journal of Materials Research , Volume 19 , Issue 6 , June 2004 , pp. 1682 - 1695
Copyright
Copyright © Materials Research Society 2004

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References

REFERENCES

1Kinloch, A.J. and Young, R.J., Fracture Behavior of Polymers (Elsevier Applied Science, New York, NY, 1983).Google Scholar
2Pocius, A.V., Adhesion and Adhesives Technology (Hanser, Cincinnati, OH, 1997).Google Scholar
3Zhuk, A.V., Evans, A.G., Hutchinson, J.W. and Whitesides, G.M.: The adhesion energy between polymer thin films and self-assembled monolayers. J. Mater. Res. 13 3555 (1998).CrossRefGoogle Scholar
4de Bruyne, N.A., in Adhesion and Cohesion, edited by Weiss, P. (Elsevier, New York, NY, 1962) pp. 47–64.Google Scholar
5McCarvill, W.T. and Bell, J.P.: Torsional test method for adhesive joints. J. Adhesion 6 185 (1974).CrossRefGoogle Scholar
6Sheller, N.B., Petrash, S. and Foster, M.D.: Variation in tenacity of protein adsorption on self-assembled monolayers with monolayer order as observed by x-ray reflectivity. Langmuir 13 1881 (1997).Google Scholar
7Carraro, C., Yauw, O.W., Sung, M.M. and Maboudian, R.: Observation of three growth mechanisms in self-assembled monolayers. J. Phys. Chem. B 102 4441 (1998).CrossRefGoogle Scholar
8Goldmann, M., Davidovits, J.V. and Silberzan, P.: Kinetics of self-assembled silane monolayers at various temperatures: Evidence of 2D foam. Thin Solid Films 329 166 (1998).CrossRefGoogle Scholar
9Heise, A., Menzel, H., Yim, H., Foster, M.D., Wieringa, R.H., Schouten, A.J., Erb, V. and Stamm, M.: Grafting of polypeptides on solid substrates by initiation of N-carboxyanhydride polymerization by amino-terminated self-assembled monolayers. Langmuir 13 723 (1997).CrossRefGoogle Scholar
10Heise, A., Stamm, M., Rauscher, M., Menzel, H. and Duschner, H.: Mixed silane self-assembled monolayers and their in situ modification. Thin Solid Films 327–329, 199 (1998).CrossRefGoogle Scholar
11Yang, J.Y.M. and Frank, C.W.: Composition of binary self-assembled monolayers of alkyltrichlorosilanes. ACS Symposium Series 695, 67 (1998).CrossRefGoogle Scholar
12Russell, T.P.: X-ray and neutron reflectivity for the investigation of polymers. Mater. Sci. Rep. 5 171 (1990).CrossRefGoogle Scholar
13Chai, H.: Deformation and failure of adhesive bonds under shear loading. J. Mater. Sci. 28 4944 (1993).CrossRefGoogle Scholar
14Adams, R.D. and Wake, W.C.: Structural Adhesive Joints In Engineering, (Elsevier Applied Science, New York, NY, 1984).CrossRefGoogle Scholar
15Kent, M.S., Yim, H., Matheson, A., Cogdill, C., Nelson, G. and Reedy, E.D.: Use of self-assembled monolayers at variable coverage to control interface bonding in a model study of interfacial fracture: Pure shear loading. J. Adhesion 75 267 (2001).CrossRefGoogle Scholar
16Yamada, S. and Israclachvili, J.: Friction and adhesion hysteresis of fluorocarbon sufactant monolayer-coated surfaces measured with the surface forces apparatus. J. Phys. Chem. B 102 234 (1998).CrossRefGoogle Scholar
17Yoshizawa, H., McGuiggan, P., and pIsraclachvili, J.: Identification of a second dynamic state during stick-slip motion. Science 259, 1305 (1993).CrossRefGoogle ScholarPubMed
18Burns, A.R., Houston, J.E., Carpick, R.W. and Michalski, T.A.: Molecular level friction as revealed with a novel scanning probe. Langmuir 15 2922 (1999).CrossRefGoogle Scholar
19Grandbois, M., Beyer, M., Rief, M., Clausen-Schaumann, H. and Gaub, H.E.: How strong is a covalent bond? Science 283 172 (1999).CrossRefGoogle ScholarPubMed
20Stevens, M.J.: Interfacial fracture between highly cross-linked polymer networks and a solid surface: Effect of interfacial bond density. Macromolecules 34 2710 (2001).CrossRefGoogle Scholar
21Lenhart, J.L. and Wu, W.L.: Deviations in the thermal properties of ultrathin polymer network films. Macromolecules 35 5145 (2002).CrossRefGoogle Scholar