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Osiander / MEMS and microstructures in Aerospace applications  DK3181_c015 Final Proof page 340 1.9.2005 12:53pm




                   340                       MEMS and Microstructures in Aerospace Applications



                   TABLE 15.3
                   Environmental Effects and the Principal Failures Induced on MEMS Devices —
                   Continued

                   Environment             Principal Effects      Typical Failures Induced
                   Low pressure     Expansion                 Fractures
                                                              Explosive expansion
                                    Outgassing                Alteration of electrical properties
                                                              Loss of mechanical strength
                                    Reduced dielectric strength of air  Insulation breakdown and arc-over
                                                              Corona and ozone formation
                   Solar radiation  Actinic and physicochemical reactions  Surface deterioration
                                                              Alteration of electrical properties
                                    Embrittlement
                                                              Discoloration of materials
                                                              Ozone formation
                   Particulate      Abrasion                  Increased wear
                                    Clogging                  Interference with function
                                                              Alteration of electrical properties
                   High air or gas  Force application         Structural collapse
                     pressure
                                                              Interference with function
                                                              Loss of mechanical strength
                                    Deposition of materials   Mechanical interference and
                                                                clogging
                                                              Abrasion accelerated
                                    Heat loss (low velocity)  Accelerates low-temperature effects
                                    Heat gain (high velocity)  Accelerates high-temperature effects
                   Temperature shock  Mechanical stress       Structural collapse or weakening
                                                              Seal damage
                   High-speed particles  Heating              Thermal aging
                     (nuclear irradiation)
                                                              Oxidation
                                    Transmutation and ionization  Alteration of chemical, physical, and
                                                                electrical properties
                                                              Production of gases and secondary
                                                                particles
                   Zero gravity     Mechanical stress         Interruption of gravity-dependent
                                                                functions
                                    Absence of convection cooling  Aggravation of high-temperature
                                                                effects
                   Ozone            Chemical reactions        Rapid oxidation
                                    Crazing, cracking         Alteration of electrical properties
                                    Embrittlement             Loss of mechanical strength
                                    Granulation               Interference with function
                                    Reduced dielectric strength of air  Insulation breakdown and arc-over
                   Explosive        Severe mechanical stress  Rupture and cracking
                     decompression                            Structural collapse



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