Wiring substrate
A component (capacitor) of the high-frequency circuit provided on a first surface of the glass substrate, and the bottom of the through hole in the glass substrate on the first surface have an overlapping part on the first surface. As a result, the capacitor is formed directly above the via, that is, the through hole, thereby eliminating the need for conductive wiring from the via to the capacitor. In addition, by forming a capacitor on a very flat glass substrate before forming the through hole, and forming the through hole after that, it is possible to stably form the capacitor.
1 . A wiring substrate comprising a glass substrate having a through hole and a capacitor on a first surface of the glass substrate,
wherein a bottom of the through hole on the first surface and the component forming the high-frequency circuit have an overlapping part on the first surface;
the capacitor comprises (a) a first conductive layer in direct contact with the first surface of the glass substrate over the through hole, (b) an insulator layer over and in direct contact with the first conductive layer and (c) a second conductive layer over and in direct contact with the insulator layer, the first conductive layer being flush and parallel with the first surface of the glass substrate.
2 . The wiring substrate according to claim 1 , wherein the through hole is filled with a material having a coefficient of thermal expansion (CTE) of 40 ppm/K or lower.
3 . The wiring substrate of claim 1 , wherein a diameter of an opening of the through hole on the first surface is smaller than a diameter of an opening of the through hole on a second surface opposite to the first surface.
4 . The wiring substrate of claim 1 , wherein the first conductive layer has a part with a greater thickness at the bottom of the through hole than at a part of the first conductive layer that does not overlap with the through hole.
5 . The wiring substrate according to claim 1 , further comprising (i) a third conductive layer on a side wall of the through hole and (ii) a dielectric material in a central part of the through hole, the dielectric material being surrounded by the third conductive layer and in direct contact with the third conductive layer.
6 . A wiring substrate comprising (ii) a glass substrate having a through hole; (ii) a component forming a high-frequency circuit on a first surface of the glass substrate, (iii) a first conductive layer on a side wall of the through hole and (iv) a dielectric material in a central part of the through hole, the dielectric material being surrounded by the first conductive layer and in direct contact with the first conductive layer
wherein a bottom of the through hole on the first surface and the component forming the high-frequency circuit have an overlapping part on the first surface.
7 . The wiring substrate according to claim 6 , wherein the through hole is filled with a material having a coefficient of thermal expansion (CTE) of 40 ppm/K or lower.
8 . The wiring substrate of claim 6 , wherein a diameter of an opening of the through hole on the first surface is smaller than a diameter of an opening of the through hole on a second surface opposite to the first surface.
9 . The wiring substrate of claim 6 , wherein a second conductive layer of the component forming the high-frequency circuit in contact with the first surface has a part with a greater thickness at the bottom of the through hole than at a part of the second conductive layer that does not overlap with the through hole.
10 . The wiring substrate of claim 6 , wherein the component forming the high-frequency circuit is a capacitor.