Electrothermally deformable levelling pad

Claim 1

An electrically heated alignment pad which comprises at least one flat plate member of thermoplastic resin, and at least one thin flat electric heater having one surface laying against substantially the whole flat surface of said plate member for heating said plate member to soften said plate member, the other surface of said heater adapted to be held in electrically insulated relationship to the surface supporting it and to an article to the aligned, said plate member and heater having a structure the thickness of which is reduced when an external compressive force is applied thereto when said plate member is in the heat softened condition, whereby an object through which the compressive force is applied can be moved by the reduction of thickness of the alignment pad for adjusting the position thereof in the direction of the force being applied to the alignment pad; said plate member having a plurality of apertures therein into which portions of said plate member around said apertures flow laterally upon the softening of said plate member when said compressive force is applied thereto and to be filled up with melted portion of the thermoplastic resin when the latter is heated; said thermoplastic resin being a random copolymerized polyester which comprises an acid component, which contains an aromatic carboxylic acid and an aliphatic dicarboxylic acid having not less than 6 carbon atoms, the mole ratio of the aromatic carboxylic acid residue relative to the aliphatic dicarboxylic acid residue relative to the aliphatic dicarboxylic acid residue in said copolymer being within the range of 40/60 to 95/5, and a glycol component which is at least one compound selected from the group consisting of an aliphatic diol, an aromatic diol and an alicyclic diol.