AFM indentation method used for elastic modulus characterization of interfaces and thin layers |
| |
Authors: | M A Monclus T J Young D Di Maio |
| |
Affiliation: | (1) National Physical Laboratory (NPL), Hampton Road, Teddington, TW11 0LW, UK;(2) The University of Surrey, Guildford, Surrey, GU2 7XH, UK |
| |
Abstract: | Atomic force microscopy (AFM) is increasingly being used as a nanoindentation tool to measure local elastic properties of
surfaces. In this article, a method based on AFM in force volume (force curve mapping) mode is employed to measure the elastic
modulus distribution at the interface of a glass flake-reinforced polypropylene sample and at a lead-free Cu–solder joint.
Indentation arrays are performed using a diamond AFM tip. The processing of experimental AFM indentation data is automated
by customized software that can analyse and calibrate multiple force curves. The analysis algorithm corrects the obtained
force curves by selecting the contact point, discarding the non-contact region and subtracting the cantilever deflection from
the measured force curve in order to obtain true indentation curves. A Hertzian model is then applied to the resulting AFM
indentation data. Reference materials are used to estimate the tip radius needed to extract the elastic modulus values. With
the proposed AFM measurement method, we are able to obtain high-resolution maps showing elastic modulus variations around
a composite interface and a Cu–solder joint. No distinct interphase region is detected in the composite case, whereas a separate
intermetallic layer (1–2 μm thick) of much higher Young’s modulus (~131 GPa) than Cu and solder material is identified in
the Cu–solder joint. Elastic modulus results obtained for the Cu (~72 GPa), solder (~50 GPa) and glass (~65 GPa) materials
are comparable to the results obtained by instrumented indentation ~73, ~46 and ~61 GPa], which accentuates the potential
of this method for applications requiring high lateral resolution. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|