METHOD FOR PRODUCING WATERPROOF SOUND-TRANSMITTING FILM, WATERPROOF SOUND-TRANSMITTING FILM, AND ELECTRONIC DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a waterproof sound-transmitting film suitable for improvement of waterproofness and securement of a sound-transmitting property.SOLUTION: The waterproof sound-transmitting film 10 includes a polytetrafluoroethylene (PTFE) film 20. The PTFE film 20 is obtained either by applying pressure on only a part of a main surface of a PTFE porous film in a thickness direction of the PTFE porous film, the PTFE porous film having a pore structure obtained by stretching a PTFE sheet and including a plurality of fibrils and a space between the plurality of fibrils, or by applying pressure on a part of the main surface of the PTFE porous film more strongly than on a remaining part of the main surface other than this part in the thickness direction of the PTFE porous film. The PTFE 20 includes a low density part 21 having a pore structure and a high density part 22 having less porosity than the low density part 21.