Another category of microwave materials are glasses. Glass in any form, including glass fiber, is a dielectric, or very low conductor of electrical current. Borosilicate glass is used because of its unique sealing properties. Glass composites can be engineered to provide specific dielectric properties.
| MATERIAL |
Symbol or formula |
Relative Dielectric Constant
 |
Dissipation Factor tan
|
Mass Density
(gr/cc) |
Melting Point
°C |
Melting Point
°F |
Temp Coefficientof Expansion
(ppm/°C) |
| Corning 0080 |
soda lime |
|
|
2.47 |
696 |
1285 |
9.4 |
| Corning 0088 |
|
|
|
|
|
|
|
| Corning 7050 |
soda borosilicate |
|
|
2.24 |
703 |
1297 |
4.6 |
| Corning 7052 |
alkali barium borosilicate |
4.9 |
|
2.28 |
712 |
1314 |
4.7 |
| Corning 7056 |
alkali borosilicate |
5.7 |
|
2.29 |
718 |
1324 |
5.2 |
| Corning 7070 |
lithia potash borosilicate |
4.1 |
|
2.13 |
|
|
3.2 |
| Corning 7740 |
borosilicate Pyrex |
5.1 |
|
2.23 |
821 |
1510 |
3.3 |
| Corning 7913 |
96% Silica, Vycor |
3.8 |
|
2.18 |
1530 |
2786 |
7.5 |
| Corning 9010 |
alkali barium |
|
|
2.64 |
646 |
1195 |
8.9 |
| Corning 9013 |
alkali barium |
|
|
2.64 |
656 |
1213 |
8.9 |
| Schott 8250 |
borosilicate |
4.9 |
0.0022 |
2.28 |
720 |
1328 |
5 |