Abstract: Perfluoropolyethers having an average molecular weight higher than 390 and respectively having a kinematic viscosity lower than 8.5 cSt (at 20.degree. C.), and such as to distill by not more than 10% at temperatures lower than 140.degree. C., and by at least 90% at temperatures not higher than 260.degree. C., or, in the case in which the perfluoropolyether does not contain CF (CF.sub.3) CF.sub.2 O units, having a viscosity lowr than 18 cSt (at 20.degree. C.), and such as to distill by not more than 10% at temperatures lower than 140.degree.C., and by at elast 90% at temperatures not higher than 280.degree. C., are used as the only high-temperature and low-temperature working fluid in the Thermal Shock Tests to which the electronic components are submitted, and at the same time are advantageously used in other tests used in the electronic industry, such as the Gross Leak Test and the Burn in Test, allowing the operators in this field to use only single fluid for a whole set of uses.

Abstract: The cross-linking or curing of thermosetting resins and of hot curable elastomers is carried out by heating the material or the article comprising the resin (or the elastomer) by saturated vapor of the commercial perfluoropolyether having an average boiling point corresponding to the temperature necessary for the cross-linking and having a point range not exceeding 12.degree. C. (measured according to ASTM D 1078) in the presence of a chlorofluorohydrocarbon secondary vapor.

Abstract: Perfluoropolyethers having an average molecular weight higher than 390 and respectively having a kinematic viscosity lower than 8.5 cSt (at 20.degree. C.), and such as to distill by not more than 10% at temperatures lower than 140.degree. C., and by at least 90% at temperatures not higher than 260.degree. C., or, in the case in which the perfluoropolyether does not contain CF(CF.sub.3)CF.sub.2 O units, having a viscosity lower than 18 cSt (at 20.degree. C.), and such as to distill by not more than 10% at temperatures lower than 140.degree. C., and by at least 90% at temperatures not higher than 280.degree. C., are used as the only high-temperature and low-temperature working fluid in the Thermal Shock Tests to which the electronic components are submitted, and at the same time are advantageously used in other tests used in the electronic industry, such as the Gross Leak Test and the Burn in Test, allowing the operators in this field to use one single fluid for a whole set of uses.

Abstract: Electronic components are welded or soldered or bonded to a support by arranging said components on the surface of the support and/or in holes piercing the support, in the presence of soldering materials having binding properties, and by then putting the thus-obtained assembly in contact with a perfluoropolyether in the liquid state, said perfluoropolyether having a temperature at least equal to that at which the soldering material develops its binding properties.

Abstract: Oxetane-structure fluids of well-defined composition and free from not completely fluorinated compounds, characterized in that they have at least a perfluoroether chain bound to an oxetane ring, having improved characteristics for special applications, being liquid up to temperatures of at least -70.degree. C., having boiling temperatures in the range of from 50.degree. to 270.degree. C. or higher, and a very high range between the boiling temperature and the pour point.

Abstract: Elastomeric compositions vulcanizable with peroxides, consisting of a fluoroelastomer based on vinylidene fluoride and containing small quantities of brominated or iodinated olefine as comonomer, admixed with from 1% to 25% by weight of perfluoropolyether or polycondensation derivatives thereof such as perfluoropolyamides.