The present disclosure provides systems and methods for assembling a subassembly for use in manufacturing an implantable device header. A method includes placing a first split web into a top platen, placing a second split web into a bottom platen, placing a conductor assembly and an antenna assembly in the bottom platen on top of the second split web, compressing the top and bottom platens together, heating the top and bottom platens until a predetermined temperature and a predetermined pressure are reached, such that first split web is fused to the second split web to form the subassembly, separating the top and bottom platens, and removing the formed subassembly.
