The structural design of a glazed alumina substrate for use in a hybrid IC repeater in the CS-36M submarine cable system is studied. The thickness of the alumina substrate, the thickness of the glaze, and the thermal expansion coefficient of the glass used for the glaze, are theoretically determine for the large (110 mm in diameter) substrate in terms of the load stress when the repeater is installed, the thermal strain when the glaze is formed, and displacement due to lateral pressure. It is found that the desirable thickness of the alumina substrate is approximately 2 mm, the desirable glaze thickness is approximately 65 µm, and the desirable thermal expansion coefficient is (7.77.5)10-6-1. A glazed alumina substrate is fabricated on the basis of these structural design parameters, and it is subjected to the mechanical strength test and form test prescribed for the CS-36M submarine cable system. The results prove that the substrate has sufficient mechanical strength and that there is no deformation problem. The glazed alumina substrate developed in this study is applied in a repeater used in the CS-36M submarine cable system and it contributes to the very high reliability of the repeater.

Ceramic plates and glaze glass are studied as the materials employed in developing a highly reliable glazed ceramic substrate. The glazed ceramic substrate is fabricated by applying a thin coating of glass to a 2 mm thick ceramic plate. The substrate is designed for use in a hybrid IC repeater in the CS-36M submarine cable system. The glazed ceramic substrate must have sufficient mechanical strength to withstand the stress under load occurring during the repeater installation, the surface smoothness and heat resistance required during forming of the repeater circuit, and the high electrical resistance to assure long-term, stable operation of the repeater circuit. A comparative study was made of alumina and beryllia for surface form, mechanical strength, heat resistance, and electrical resistance under required conditions for repeater parts in the CS-36M submarine cable system. As a result, an alumina plate with an Al2O3 content greater than 97% was selected as the ceramic plate in view, especially, of its surface form and mechanical strength. The glass used for glaze must have excellent glass formability, heat resistance which allows no change in form up to 600, and long-term, stable electrical resistance. From this point of view, excellent compositions were developed on the basis of SiO2-Al2O3-CaO and SiO2-Al2O3-BaO systems. A large glazed ceramic substrate, 110 mm in diameter, was fabricated using the ceramic plate and glass selected here and it was applied in a repeater in the CS-36M submarine cable system.