Abstract
In addition to being used for pattern transfer, the negative photoresist SU-8 is widely used as a structural material in microelectromechanical systems (MEMS). Due to its good photopatternability, SU-8 has lower manufacturing costs than many other materials, but its mechanical properties are relatively weak to some extent, which limits its performance. The mechanical properties of epoxy-like SU-8 can be enhanced by adding micro- or nano-fillers such as carbon nanotube, clay, and SiC nanowire, which have superior elastic modulus. In this study, SiC nanowires were used to improve the mechanical properties of SU-8 while the SU-8 retains its photopatternability. The SiC nanowires were uniformly dispersed in SU-8 by stirring and ultrasonication. SU-8 materials with different SiC nanowire contents were fabricated into dog bone samples by lithography. The elastic modulus, storage modulus, and damping factor of the samples were measured by the Dynamic mechanical analysis (DMA) Q800. The experiment result shows that the rigidity and toughness increased, and the damping reduced. The 2 wt% SiC nanowires-reinforced SU-8 had a 73.88% increase in elastic modulus and a 103.4% increase in elongation at break. Furthermore, a spring component made by SiC-doped SU-8 could withstand greater acceleration. The SiC nanowires-reinforced SU-8 has the potential to meet higher requirements in the design and manufacture of MEMS and greatly reduce the manufacturing costs of MEMS devices.
Highlights
As a negative photoresist, SU-8 is increasingly used as a structural material for microelectromechanical systems (MEMS) and microfluidics in addition to being used for pattern transfer.[1]
The effect of SiC nanowires addition on the elastic modulus and elongation at break of the SU-8 is illustrated in Table 1 and Fig. 8, respectively
To study the mechanism of pure SU-8 and SiC-reinforced SU-8, the fracture surfaces of broken samples were comparatively observed by scanning electron microscopy (SEM)
Summary
SU-8 is increasingly used as a structural material for microelectromechanical systems (MEMS) and microfluidics in addition to being used for pattern transfer.[1] Because of its low manufacturing cost, good chemical stability, and thermomechanical properties,[2] SU-8 has advantages over other materials in some cases. The mechanical properties of epoxy resin have been improved to some extent by adding micro- or nano-fillers.[4,5,6] many studies have improved the mechanical properties of SU-8 by adding fillers such as GO,[7] single-wall carbon nanotubes, gold nanospheres[8] and multiwalled carbon nanotubes.[9,10] the improvement is small, and the addition of these materials will greatly affect the electrical insulation of SU-8. It has been found that the nano-sized SiC incorporated into the epoxy significantly improves the glass transition temperature and elastic modulus of the epoxy.[15] In Ref. The SU-8 negative photoresist was purchased from MicroChem (USA)
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