Heat sealing is the process of sealing one thermoplastic to another similar thermoplastic using heat and pressure.[1] The direct contact method of heat sealing utilizes a constantly heated die or sealing bar to apply heat to a specific contact area or path to seal or weld the thermoplastics together. Heat sealing is used for many applications, including heat seal connectors, thermally activated adhesives, film media, plastic ports or foil sealing.

Heat seal connectors are used to join LCDs to PCBs in many consumer electronics, as well as in medical and telecommunication devices.

Heat sealing of products with thermal adhesives is used to hold clear display screens onto consumer electronic products and for other sealed thermo-plastic assemblies or devices where heat staking or ultrasonic welding are not an option due to part design requirements or other assembly considerations.