Abstract
As fluidic microelectromechanical devices are developing and often attached to, or embedded in, large, complex, and expensive systems, the issues of modularity, maintenance, and subsystem replacement arise. In this work, a robust silicon connector suitable for high-pressure applications—likely with harsh fluids—in the temperature range of +100 to [Formula: see text] C is demonstrated and tested together with a stainless steel nipple representing a simple and typical macropart. With a micromachined circular membrane equipped with a 5 μm high ridge, this connector is able to maintain a leak rate below [Formula: see text] scc/s of gaseous helium with a pressure of up to 9.7 bar. Degradation of the sealing performance on reassembly is associated with the indentation of the ridge. However, the ridge makes the sealing interface less sensitive to particles in comparison with a flat reference. Most evaluation is made through the so-called heat-until-leak tests conducted to determine the maximum working temperature and the sealing mechanism of the connector. A couple of these are followed by cryogenic testing. The effect of thermal mismatch of the components is discussed and utilized as an early warning mechanism.
Highlights
Introduction and BackgroundIt almost follows from its definition that interfaces are challenging
In the finite element method (FEM) calculation of the Fax and Pridge, the ridge surface was displaced to the plane of the solid part of the samples, so that no indentation of the ridge in the nipple was taken into account
Isolation of the test chamber in a cabinet constantly flushed with gaseous nitrogen, and as an additional measure, exchange of the aluminium gasket to one of leads resulted in a leak rate below 2.0 × 10−8 scc/s GHe, as shown in Figures 10 and 12, respectively
Summary
It almost follows from its definition that interfaces are challenging. Neglecting the specific operating conditions, gluing [1, 2], bonding [3], welding [4], and interfacing by means of o-rings, flexible tubes [2, 5,6,7], or polymer casting [8, 9] have been successful approaches. A permanent interface is leak tight, and requires similar thermal expansion of the material involved, while a dismountable interface often admits use of material with different thermal expansion, supports the need of exchange of devices, but may exhibit significant leakage. Elastomeric o-rings and gaskets in dismountable connectors suffer from compression set, hysteretic recovering, and thermal degradation [10,11,12,13]
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