Attach Photosensitive Film.
After PTH,FPC PCB will be bonded with dry film by hot press roll.The dry film will be laminated on pretreated boards as the etching resist.Since the dry film is sensitive to ultraviolet light,the operation need to be proceeded in a yellow light cleanroom for preventing polymerization before the image exposure
Roll-to-roll mode is used to mass-produced FPC.This film laminating operation is different from panel-to-panel mode and needs different laminating equipment.