Capacitor and method of making same
A capacitor having a dielectric consisting of a glass layer with an alkali metal oxide content of at most 2 wt % and a thickness of at most 50 μm is provided. The capacitor includes at least two metal layers which are separated by the glass layer. The glass layer is preferably produced by a down-draw method or by an overflow down-draw fusion method.
1. A capacitor comprising:
at least two metal layers; and
a dielectric layer separating said at least two metal layers, said dielectric layer being configured as a glass layer having a fire-polished surface, said glass layer having an alkali metal oxide content of at most 0.5 wt % and having a thickness of at least 5 μm and at most 30 μm,
wherein said glass layer glass comprises the following components in weight percent based on oxide:
SiO 2
45-70;
Al 2 O 3
5-25;
B 2 O 3
1-16;
alkaline-earth metal oxides
1-30; and
alkali metal oxides
0-1.
2. The capacitor of claim 1 , wherein said glass layer consists of a glass having an electrical conductivity of at most 10 −15 S/cm.
3. The capacitor of claim 1 , wherein said glass layer consists of a glass having a dielectric loss angle of at most 0.001 at 1 kHz.
4. The capacitor of claim 1 , wherein said dielectric layer has a thickness of at most 30 μm.
5. A capacitor comprising:
at least two metal layers; and
a dielectric layer separating said at least two metal layers, said dielectric layer being configured as a glass layer having a fire-polished surface, said glass layer being essentially free of alkali metal oxides and having a thickness of at most 50 μm,
wherein said glass layer consists of a glass comprising the following components in weight percent based on oxide:
SiO 2
40-75,
Al 2 O 3
1-25,
B 2 O 3
0-16,
alkaline-earth metal oxides
0-30, and
alkali metal oxides
0-2.
6. The capacitor of claim 5 , wherein said glass layer has a thickness of at least 5 μm.
7. The capacitor of claim 5 , wherein said at least two metal layers and said glass layer are wound to form a layer unit and said at least two metal layers are respectively electrically connected to terminals.
8. The capacitor of claim 5 , wherein said glass layer consists of a glass having an alkali metal oxide content of at most 0.1 wt %.
9. The capacitor of claim 5 , wherein said glass layer consists of a glass having an electrical conductivity of at most 10 −15 S/cm.
10. The capacitor of claim 5 , wherein said glass layer consists of a glass having a dielectric loss angle of at most 0.001 at 1 kHz.
11. The capacitor of claim 5 , wherein said glass comprises the following components in weight percent based on oxide:
SiO 2
45-70;
Al 2 O 3
5-25;
B 2 O 3
1-16;
alkaline-earth metal oxides
1-30; and
alkali metal oxides
0-1.
12. The capacitor of claim 5 , wherein said glass layer has a maximum mean roughness depth of at most 1 nanometer.
13. The capacitor of claim 5 , wherein said glass layer has a quality of at least 20·10 12 V/mm 3 , said quality being defined as a ratio of a breakdown field strength to a product of a thickness and a roughness of a surface of said glass layer.
14. A capacitor comprising:
at least two metal layers; and
a dielectric layer separating said at least two metal layers, said dielectric layer being a glass layer having a fire-polished surface with a maximum mean roughness depth RMS of at most 1 nanometer, said glass layer being essentially free of alkali metal oxides and having a thickness of at most 50 μm,
wherein said glass layer consists of a glass which comprises the following components in weight percent based on oxide:
SiO 2
45-70,
Al 2 P 3
5-25,
B 2 O 3
1-16,
alkaline-earth metal oxides
1-30, and
alkali metal oxides
0-1.
15. The capacitor of claim 1 , wherein said glass layer has laser cut edges forming a fire-polished surface on the laser cut edges.
16. The capacitor of claim 5 , wherein said glass layer has laser cut edges forming a fire-polished surface on the laser cut edges.
17. The capacitor of claim 14 , wherein said glass layer has laser cut edges forming a fire-polished surface on the laser cut edges.