Patent ID: 8187987

Claim:
An article suitable for housing, enclosing or covering the components of a portable electronic device, the article comprising an ion exchanged alkali-aluminosilicate glass consisting essentially of 64 mol %≦SiO 2 ≦68 mol %; 12 mol %≦Na 2 O≦16 mol %; 8 mol %≦Al 2 O 3 ≦12 mol %; 0 mol % ≦B 2 O 3 ≦3 mol %; 2 mol %≦K 2 O≦5 mol %; 4 mol %≦MgO≦6 mol %; and 0 mol %≦CaO≦5 mol %, wherein: 66 mol %≦SiO 2 +B 2 O 3 +CaO≦69 mol %; Na 2 O+K 2 O +B 2 O 3 +MgO+CaO+SrO>10 mol %; 5 mol %≦MgO+CaO+SrO≦8 mol %; 2 mol %≦Na 2 O−Al 2 O 3 ≦6 mol %; and 4 mol %≦(Na 2 O+K 2 O)−Al 2 O 3 ≦10 mol %, and exhibiting radio and microwave frequency transparency, as defined by a loss tangent of less than 0.03 and at a frequency range of between 15 MHz to 3.0 GHz, infrared transparency, a fracture toughness of greater than 0.60 Mpa·m 1/2 , a 4-point bend strength of greater than 350 MPa, a Vickers hardness of at least 450 kgf/mm 2 , a Vickers median/radial crack initiation threshold of at least 5 kgf, a Young's Modulus ranging between 50 to 100 GPa, a thermal conductivity of less than 2.0 W/m° C. and at least one of the following attributes: (i) a compressive surface layer having a depth of layer (DOL) greater than or equal to 20 μm and a compressive stress greater than 400 MPa, or, (ii) a central tension of more than 20 MPa.