Failure mechanisms of pressurized microchannels: model and experiments

Abstract

Microchannels were created by fusion bonding of a Pyrex cover to a thermally oxidized silicon wafer, which contained anisotropically etched grooves. Such channels are frequently used in microfluidic handling systems, for example, in chemical analysis. Since in some of these labs-on-a-chip, in particular those used in liquid chromatography, the channels are subjected to high pressures of up to a few hundred bar, it is important to have information about the mechanical stability of the channel chip, in particular of the wafer bond involved in it. The latter is the subject of this paper. The maximum pressure that can be applied to several different channel chips was investigated experimentally. In order to find the relation among this maximum pressure, channel geometry, materials elasticity, and bond energy, an energy model was developed that is generally applicable to all types of wafer bonds. It was shown that the model is substantiated by the experimental pressure data, from which it could be calculated that the effective bond energy increased from 0.018 to 0.19 J/m 2 for an annealing temperature ranging from 310 to 470 C. [517]Index Terms-Bond energy, fusion bonding, microchannels.

Transparent silicon/glass microreactor for high-pressure and high-temperature reactions

“…The tensile test results indicate that the operating pressure and temperature region of the soldered microfluidic connection is suitable for the proposed operating conditions. The mechanical strength of the Si/glass reaction channel on the other hand can be estimated by beam theory [40]. The maximum applicable pressure is an inverse function of the square of the channel width.…”

Factors affecting silicon membrane burst strength

“…The effect of delamination between the microvalve Pyrex and silicon membrane layers was studied ( Figure 5) [17]. In this instance, membrane fracture per se does not occur.…”

“…These factors include: membrane shape at the intersection between membrane, and structural frames or sidewalls; membrane thickness; membrane surface roughness; membrane mis-orientation to the principal crystallographic axes [9,10]; wafer starting material; membrane stress; and microstructure and shape at the membrane-Pyrex anodic bond interface [17]. Measurements of fracture strength versus these factors are made.…”

“…yre x T hickn e ss (m m ) De la m in a tion P re ssure (M P a ) Modeling the effect of Pyrex-silicon delamination (after[17]). Proc.…”

Morphology and stress at silicon-glass interface in anodic bonding

“…Anodic bonding, as an advanced connection technology invented by Wallis and Pomerantz in 1969 [1], has been widely used in the field of micro-electronic mechanical system (MEMS) for micro-channel package [ 2], pressure sensor [3], accelerometer [ 4], micro energy equipment [5] and so on. In recent years, the main progresses in anodic bonding focused on new applications and new materials of anodic bonding.…”