SU8‐Silver Photosensitive Nanocomposite

Abstract

Composite materials offer a combination of properties and a diversity of applications, which cannot be obtained with metals, ceramics or polymers alone. In particular, the insertion of a conductive phase (metallic or inorganic powders or conductive polymers) in an insulating polymer matrix, can result in an enhancement of its electrical conductivity. Various studies have been focused on such electrically conductive polymer composition (ECPCs), which do not have the disadvantages of the pure metal (high density, low chemical resistance, complex manufacturing process). The powder loaded polymer becomes a functional material with specific properties, and can be used for electrical or electromagnetic applications, etc. [1,2] The case of ECPCs based on epoxy resins, are of particular interest to understand the properties of binary composites (morphology, electrical and thermal conductivity), which are obtained in most cases after a heat treatment to crosslink the ECPCs materials. Their main application is conductive adhesives used in the electronic field for connecting and bonding, but it can also be used for manufacturing sensors. [3±5] In this paper we report a new conductive photosensitive composite material, allowing the direct manufacture of electrically conductive micro-components. It is based on a blend containing silver particles embedded in SU-8, an epoxy photopolymer essentially used for the fabrication of high aspect ratio structures by UV-LIGA. SU-8 components are useful for MEMS, fluidic and packaging applications, [6,7] but also as masters for micro-injection-molding (Fig. 1).Nanocomposite characterizations: Formulations containing up to 40 vol.% of silver filler were produced to evaluate the effect of the insertion of silver particles in the photopolymer matrix, both on the photo-polymerization phenomenon and on electrical conductivity of the resulting photo-patterned structures.

Effect of filler behavior on nanocomposite SU8 photoresist for moving micro-parts

“…The polymerization is effectuated by Mask Aligner, either in front side or backside mode. At last post exposure bake of 15 min is done followed the development of the structure by appropriate developer [8].…”

Free-standing nanocomposites with high conductivity and extensibility

“…The percolation thresholds of pure CNTs and pure Ag nanoparticles in a SIS polymer matrix were about 1 and 37 wt%, respectively. In general, the metallic continuum in a dielectric matrix can be achieved with high Ag loadings in the range of 30~80 wt% [27,28]. Above the percolation threshold, the adjacent Ag fillers coalesce inducing the formation of larger nanoclusters [27].…”

Design and fabrication of an ac-electro-osmosis micropump with 3D high-aspect-ratio electrodes using only SU-8

“…Lastly, this type of processing is expensive and time consuming. Although using conductive polymer such as conductive SU-8 [12,13] to make 3D electrodes' structures represents a plausible solution, the thickness and resolution remain a problem in addition to the difficulty of making small structures (<20 μm).…”