Dynamic mechanical properties of photo resist thin films

Abstract

Photo resist thin films have mainly been used and investigated for versatile applications of micro electronic mechanical systems because of its outstanding aspect ratio and attainable film thickness. An accurate structure properties derived from validated material characterization is required in engineering applications. In this work, dynamic responses of photo resist thin films are tested by a nanoindentation in association with a dynamic mechanical analysis, where the thin film is coated on a silicon wafer by spin coating. The results show that the storage modulus of the photo resist thin film remains constant at the beginning and then increases as the indentation depth increases. Meanwhile, the loss modulus increases as the indentation depth increases. Varying the film thickness shows that the substrate effect plays an important role in determining the dynamic properties of thin films. However, the results agree well with the bulk material when the amplitude of nanoindentation is relatively small. It illustrates the dynamic mechanical analysis can be an efficient method to characterize the viscoelastic properties of thin films, but proper attention on the test parameters is needed.

Towards quantitative modelling of surface deformation of polymer micro-structures under tactile scanning measurement

“…Let the contact strain ε c and the contact stress σ c be calculated according to equations ( 6) and (7), figure 4 can then be redrawn as figure 5 so as to demonstrate the experimental relationship between ε c and σ c .…”

“…In the past years various efforts have been made to determine the mechanical properties of polymers, and photoresists in particular [6][7][8][9][10], yielding comprehensive knowledge about the material properties of thermoplastic polymers used in micro-system technology, e.g. PMMA, SU-8, Ormocomp and so on.…”

A practical method for simultaneous determination of Poisson’s ratio and Young’s modulus of elasticity of thin films

“…Thin films have found increasing applications in many advancing technologies [1][2][3][4][5][6]. To increase the reliability, lifespan and structural stability of functional thin films and thin film structures, a better characterization of mechanical properties such as Poisson's ratio and Young's modulus of elasticity, which play an important role in the mechanical performance of thin films, is often found to be necessary.…”

Bi-directional homogenization equivalent modeling for the prediction of thermo-mechanical properties of a multi-layered printed circuit board (PCB)

“…It was also found that the viscoelasticity of the transverse line, grid, and square patterns as a function of the frequency increased significantly at higher temperatures because of the enhanced viscoelastic characteristics of the surrounding layers, such as the BT core and PSR. However, the longitudinal line pattern showed little change with frequency even at 90 °C, because the analytical equation of this pattern is independent of the surrounding layers (see equation (13)).…”

“…Therefore, to simulate the warpage of PCB simply and accurately, equivalent modeling of Cu micro-patterns for each shape, including the effect of surrounding layers such as BT core and PSR layers, is necessary. Furthermore, raw materials for PCB such as woven glass fabric/ BT (bismaleimide triazine), composite laminate (BT core), and photoimageable solder resist (PSR) have thermo-viscoelasticity properties that change the modulus depending on time and temper ature [13,14]. For this reason, analysis of the viscoelastic thermo-mechanical deformation behavior of multi-layered PCB under the reflow process (the maximum temperature is 260 °C) is essential for the accurate prediction of the warpage in a multi-layered PCB.…”