Method of manufacturing a portable electronic device

A method of manufacturing a portable electronic device capable of processing information, the portable electronic device including a body arranged to be securable to a user and at least one electronic assembly for processing information, wherein the body of the portable electronic assembly is formed of a layer of plastic material which gives the portable electronic device a shape and thickness, the method comprising:

• overmoulding the layer of plastic material, which forms the body of the portable electronic device, on an external face of a first impermeable plastic film;
• mounting the electronic assembly for processing information on an inner face side of the first impermeable plastic film;
• and
• securing a second impermeable plastic film to the first impermeable plastic film, so as to delimit, between the first and second impermeable plastic films, an impermeable cavity which houses the electronic assembly for processing information.