A technique comprising: providing an assembly temporarily adhered on opposite sides to respective carriers by respective adhesive elements, the assembly including at least one plastic support sheet; heating the assembly while mechanically compressing the assembly between the carriers, wherein the strength of adhesion of one of said adhesive elements to the respective carrier and/or to the assembly is partially reduced during said heating of the assembly under mechanical compression; and wherein the strength of adhesion of the said adhesive element to the carrier and/or to the assembly is further reducible by further heating the said adhesive element after partially or completely relaxing the pressure at which the assembly is mechanically compressed between the two carriers.