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US 5,635,301 AGranted
Multilayered glass substrate
AssigneeNgk Spark Plug Co., Ltd.
InventorsKazuo Kondo, Asao Morikawa
Life of this patent
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Abstract
A multilayered substrate is disclosed comprising a first layer of relatively dense crystalline glass, and a second layer of a porous crystalline glass characterized by a relatively low dielectric constant bonded to the first layer. The crystalline glass in both layers is of substantially the same composition.
Claims5
A multilayered substrate comprising:
- a first layer of a crystalline glass having a porosity of less than 5% and a thickness of 10 to 20 .mu.m;
- a second layer of a crystalline glass having a closed uniform porosity therein of 30% to about 60% and a thickness of 150 to 250 .mu.m bonded to said first layer, such that said second layer has a dielectric constant of 4.0 or less;
- wherein said glass of said first layer and of said second layer has a composition of RO--Al.sub.2 O.sub.3 --SiO.sub.2 where RO is an oxide selected from the group consisting of CaO, ZnO, MgO, Li.sub.2 O, ZrO.sub.2, B.sub.2 O.sub.3, P.sub.2 O.sub.5, Y.sub.2 O.sub.3, and BaO, and wherein the average pore size of said first layer and said second layer is 10 .mu.m or less.
Dependencies are inferred from the claim text.