NOVELTY - A transfer sheet (1a) with joining film (3) having silicon skeleton with leaving group, is provided on a base material (2a). By providing energy to joining film, leaving group is disconnected and adhesiveness is expressed. A temporary assembly is obtained by bonding transfer sheet and transfer component (5a). A transfer sheet with a patterned joining film is left. By providing energy to the patterned film, the leaving group is disconnected and adhesiveness is expressed. An assembly is obtained by bonding the transfer sheet and to-be-adhered component.    USE - Joining of base material and to-be-adhered component. Uses include but are not limited to transistors, diodes, memories, quartz oscillators, reflective mirrors, optical lenses, diffraction gratings, optical filters, solar cell elements, wirings, electrodes, microreactors, pressure sensors, magnetic recording medium, LCD element, organic electroluminescent element, electrophoretic display elements, and fuel-cell components.    ADVANTAGE - The method uses a joining film having excellent weather resistance, chemical resistance, durability, and long-term preservability. The method provides assemblies having excellent dimensional stability.    DETAILED DESCRIPTION - A joining-film transfer sheet consisting of a joining film formed by plasma polymerization, and having a silicon skeleton having an atomic structure including a siloxane bond, and a leaving group consisting of organic groups and bonded with the silicon skeleton, is provided on one surface of a base material. By providing energy to the surface of joining film, the leaving group existing in the surface vicinity of the joining film is disconnected from the silicon skeleton, and adhesiveness is expressed on the surface of joining film. A temporary assembly is obtained by bonding the transfer sheet and a transfer component such that the transfer component which transfers a portion of the joining film is prepared with the joining film and transfer component adhered. The transfer component is made to transfer a portion of joining film by peeling the base material from the temporary assembly. A transfer sheet with a joining film patterned to preset shape, is left in the base material. By providing energy to the surface of the patterned joining film, the leaving group is disconnected from the silicon skeleton and adhesiveness is again expressed on the surface of joining film. An assembly is then obtained by bonding together the transfer sheet and to-be-adhered component by joining through the joining film, such that the joining film and to-be-adhered component contact.    DESCRIPTION OF DRAWING(S) - The drawing shows a longitudinal cross-sectional view explaining the joining method.    Transfer sheet (1a)    Base material (2a)    Joining film (3)    Transfer component (5a)    Recess (51)