RF (radio frequency) welding or RF heat-sealing are often used interchangeably with HF (high frequency) or di-electric heat sealing or welding. When a di-electric material comes into contact with an electromagnetic field, some portion of the electromagnetic energy will go through a change of state and be dissipated as heat with the di-electric. The degree to which this conversion of energy will occur is dependent on the atomic and molecular structure of the material, the frequency of the electromagnetic field and the field strength.
The term di-electric heating correctly describes this phenomenon at any frequency, while RF or HF heating describes this process over the limited frequency range (1 to 200 megahertz).
In the case of RF or HF welding of thermoplastics, the effective mechanisms producing heat in the di-electric are dipolar and interfacial polarization.