Abstract: A printed circuit element in which the outer conductor layers of the electrical components arranged on the outer conductor layers are provided with a cover layer. The cover layer includes a heat-sealable high-temperature adhesive joined to a layer of intractable fully aromatic polyimide.The described circuit elements show very good mechanical, thermal and electrical properties and may be used advantageously inter alia in electronics, radio technology, computer technology, electric motors, aircraft and aerospace and telecommunications.

Abstract: A multilayer laminate having at least one layer of a no longer formable fully aromatic polyimide and at least one layer of substrate material, the layer of no longer formable polyimide adhering directly on one side to the layer of substrate material with a peel strength of at least 4.0 N.cm. The layer of no longer also formable polyimide is also insoluble in phenolic solvents, has a tensile strength of from 100 to 150 N.mm.sup.2, a breaking elongation of from 15 to 100%, a dielectric dissipation factor of from 1.5.times.10.sup.-3 at 1 Khz. Additionally, a layer of heat-sealable high-temperature adhesive selected from the class of polyacrylates, polysulfone resins, epoxy resins, fluoropolymer resins, silicone resins or butyl rubbers is joined to that side of the polyimide layer which is remote from the substrate material.

Abstract: A multilayer laminate having at least one layer of a no longer formable fully aromatic polyimide and at least one layer of substrate material, the layer of no longer formable polyimide adhering directly on one side to the layer of substrate material with a peel strength of at least 4.0 N/cm. The layer of no longer also formable polyimide is also insoluble in phenolic solvents, has a tensile strength of from 100 to 150 N/mm.sup.2, a breaking elongation of from 15 to 100%, a dielectric dissipation factor of from 1.5.times.10.sup.-3 to 5.times.10.sup.-3 at 1 kHz. Additionally, a layer of heat-sealable high-temperature adhesive selected from the class of polyacrylates, polysulfone resins, epoxy resins, fluoropolymer resins, silicone resins or butyl rubbers is joined to that side of the polyimide layer which is remote from the substrate material.

Abstract: The invention relates to laminates comprising at least one layer of an intractable, fully aromatic polyimide which, on one side, is directly bonded to a layer of a substrate and, on the other side, to a layer of a heat-sealable polyimide. The basic elements thus produced may be bonded to one another on the heat-sealable polyimide sides or one basic element may be bonded to another layer of substrate. Further layers may be bonded to one or both outside(s) of the laminates. The laminates may be produced by a novel temperature-controlled process. The substrates are preferably foils of metals or alloys. The multilayer laminates obtained are distinguished by outstanding mechanical, thermal and electrical properties. They may be used as reinforcing materials or for printed electrical circuits.