Low dielectric glass and fiber glass for electronic applications
Glass compositions are provided that are useful in electronic applications, e.g., as reinforcements in printed circuit board substrates. Reduced dielectric constants are provided relative to E-glass, and fiber forming properties are provided that are more commercially practical than D-glass.
1. A glass composition suitable for fiber forming comprising:
SiO 2
60-68
weight percent;
B 2 O 3
7-12
weight percent;
Al 2 O 3
9-14
weight percent;
MgO
8-14
weight percent;
CaO
0-4
weight percent;
Li 2 O
0-2
weight percent;
Na 2 O
0-1
weight percent;
K 2 O
0-1
weight percent;
Fe 2 O 3
0-1
weight percent;
F 2
0-2
weight percent;
TiO 2
0-2
weight percent; and
other constituents
0-5
weight percent total;
wherein the (Li 2 O+Na 2 O+K 2 O) content is no more than 2 weight percent and wherein the MgO content is at least twice the content of CaO on a weight percent basis.
2. The composition of claim 1 wherein the CaO content is 0-3 weight percent.
3. The composition of claim 1 wherein the MgO content is 8-13 weight percent.
4. The composition of claim 1 wherein the MgO content is 9-12 weight percent.
5. The composition of claim 1 wherein the B 2 O 3 content is no more than 11 weight percent.
6. The composition of claim 1 wherein the Al 2 O 3 content is 10-13 weight percent.
7. The composition of claim 1 wherein the constituents are selected to provide a glass having a dielectric constant (D k ) less than 6.7 at 1 MHz frequency.
8. The composition of claim 1 wherein the constituents are selected to provide a glass having a dielectric constant (D k ) less than 6 at 1 MHz frequency.
9. The composition of claim 1 wherein the constituents are selected to provide a glass having a dielectric constant (D k ) less than 5.8 at 1 MHz frequency.
10. The composition of claim 1 wherein the constituents are selected to provide a glass having a dielectric constant (D k ) less than 5.6 at 1 MHz frequency.
11. The composition of claim 1 wherein the constituents are selected to provide a forming temperature T F at 1000 poise viscosity no greater than 1370° C.
12. The composition of claim 11 wherein the constituents are selected to provide a liquidus temperature T L at least 55° C. below the forming temperature.
13. The composition of claim 1 wherein the constituents are selected to provide a forming temperature T F at 1000 poise viscosity no greater than 1320° C.
14. The composition of claim 13 wherein the constituents are selected to provide a liquidus temperature T L at least 55° C. below the forming temperature.
15. The composition of claim 1 wherein the composition comprises 0-1 weight percent of BaO and 0-2 weight percent ZnO.
16. The composition of claim 1 wherein the composition comprises essentially no BaO and essentially no ZnO.
17. The composition of claim 1 wherein other constituents, if any, are present in a total amount of 0-2 weight percent.
18. The composition of claim 1 wherein other constituents, if any, are present in a total amount of 0-1 weight percent.
19. A glass composition suitable for fiber forming comprising:
B 2 O 3
less than 12
weight percent;
Al 2 O 3
9-14
weight percent;
MgO
8-14
weight percent;
CaO
0-4
weight percent;
SiO 2
60-68
weight percent;
Li 2 O
0-2
weight percent;
Na 2 O
0-1
weight percent;
K 2 O
0-1
weight percent;
Fe 2 O 3
0-1
weight percent;
F 2
0-2
weight percent; and
TiO 2
0-2
weight percent;
wherein the (Li 2 O+Na 2 O+K 2 O) content is no more than 2 weight percent, wherein the MgO content is at least twice the content of CaO on a weight percent basis, and wherein the glass exhibits a dielectric constant (D k ) less than 6.7 and forming temperature (T F ) at 1000 poise viscosity no greater than 1370° C.
20. A glass composition suitable for fiber forming comprising:
SiO 2
60-68
weight percent;
B 2 O 3
7-12
weight percent;
Al 2 O 3
9-14
weight percent;
MgO
8-14
weight percent;
CaO
0-3
weight percent;
Li 2 O
0-2
weight percent;
Na 2 O
0-1
weight percent;
K 2 O
0-1
weight percent;
Fe 2 O 3
0-1
weight percent;
F 2
0-2
weight percent; and
TiO 2
0-2
weight percent;
wherein the (Li 2 O+Na 2 O+K 2 O) content is no more than 2 weight percent, wherein the MgO content is at least twice the content of CaO on a weight percent basis, and wherein the glass exhibits a dielectric constant (D k ) less than 5.9 and forming temperature (T F ) at 1000 poise viscosity no greater than 1320° C.