Infrared heat treatment of plastic film capacitors

A process for manufacturing plastic film capacitors comprising the steps of sprirally winding alternating layers of oriented thermoplastic dielectric film and metallic foil electrodes to form a cylinder having a plurality of turns and applying radiant energy to the cylinder to cause the dielectric film to shrink toward its unoriented state, thereby forming a rigid cylinder, wherein the transmittance of the dielectric film is such that the film will shrink progressively from the inner turns to the outer turns.

A process for manufacturing plastic film capacitors comprising the steps of:

• spirally winding at least two layers of oriented metallized dielectric thermoplastic film to thereby form a cylinder having a plurality of turns;
• and
• applying energy to the cylinder to cause the film to revert toward its unoriented state thus forming a rigid cylinder, wherein the energy is applied so that the film will shrink progressively from the inner turns to the outer turns.

In a process for manufacturing plastic film capacitors in which alternating layers of oriented thermoplastic dielectric film and metallic foil electrodes are spirally wound to form a cylinder and the resulting cylinder is heated to cause shrinkage of the dielectric film to thereby form a stable cylinder, the improvement comprising heating the dielectric windings so that the heating occurs at a progressively slower rate from the inner dielectric turns to the outer dielectric turns.

A process for manufacturing plastic film capacitors comprising the steps of:

• (a) winding alternating layers of thermoplastic dielectric film and metal to form a cylinder, each cylinder having a plurality of turns of dielectric film and metal, respectively;
• (b) applying radiant energy of a predetermined wavelength to the cylinder thereby causing shrinkage of the dielectric film, wherein the metal and dielectric windings transmit a portion of said applied radiant energy sufficient to cause the inner dielectric turns to receive an amount of energy per unit area which will cause shrinkage of the dielectric film to occur progressively from the inner turns to the outer turns.