Authors: P-T Lin and Y-W Lu
Affilation: Rutgers University, United States
Pages: 190 - 193
Keywords: PDMS bonding, blister test, line force model, delaminating force
Bonding is an important technique in microelectronics and Microelectromechanical Systems (MEMS). Especially, bonding two pieces of polydimethylsiloxane (PDMS) to make micro devices was widely used in micro actuators and BioMEMS. The PDMS bonding, however, lacked appropriate methods of quantifying its resultant strength. Our bonding strength measurements utilized a generalized blister test, which consisted of a PDMS membrane bonded to a PDMS substrate except for a circular region acting as a blister. When the blister was pressurized, a line force (i.e. force/length) normal to the substrate pulled the membrane and intended to delaminate from the substrate defining the bonding strength. The blister deformation was recorded and the blister boundary was calibrated by the least square approximation to determine the blister diameter. 5% increment of the original diameter was employed as the criteria to define the beginning of delamination and the corresponding critical pressure. The critical pressures were size dependent and inversely proportional to blister diameters, while the line forces were size independent. In other words, the critical pressures only described the device performances at particular dimensions, as the line force represented the bonding strengths and only related to the bonding conditions. In addition, SEM images revealed the fracture mechanisms and verified our line force model.
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