Electro-optic rearview mirror element with fill port filter and method of manufacturing electro-optic rearview mirror element

A method of manufacturing a variable reflectance vehicular electro-optic rearview mirror reflective element assembly, said method comprising:

• providing a front substrate having a first surface that generally faces a driver of a vehicle equipped with a mirror assembly that incorporates said rearview mirror reflective element assembly, wherein said front substrate has a second surface opposite said first surface and wherein said second surface of said front substrate has a transparent electrically conductive coating disposed thereat;
• providing a rear substrate having a third surface and a fourth surface, wherein said third surface has a conductive coating disposed thereat;
• dispensing a perimeter seal at a perimeter edge region of one of said front and rear substrates, wherein said perimeter seal has a gap between terminal ends of said perimeter seal;
• mating said front and rear substrates together, whereby said perimeter seal spaces said front and rear substrates apart and forms an interpane cavity therebetween, wherein said gap between said terminal ends of said perimeter seal provides a fill port for said mirror reflective element assembly when said front and rear substrates are mated together;
• providing a filter element at said fill port;
• filling said interpane cavity with an electro-optic medium that flows into said interpane cavity through said fill port and through said filter element, said filter element allowing said electro-optic medium to flow therethrough during said cavity filling process and limiting passage of contaminant particles to limit intrusion of contaminant particles into said interpane cavity during said cavity filling process;
• and
• plugging said fill port to substantially seal said electro-optic medium in said interpane cavity.