Nortel Networks Corporation

Bookham Technology Limited

Timothy J Durrant

Christopher G Tanner

Kenneth Snowdon

Richard Wilmshurst

Christopher Woodend

A glass fixative composition for bonding glass materials to non-glass materials is provided. The fixative composition is selected for its thermal expansion coefficient, its viscosity, its adhesion to glass, melting point, and bond strength. The glass fixative is in particular useful for bonding optical fibers to metallic materials such as Kovar. The low melting point of the glass fixative enables localized heating methods to be used, in particular, as Kovar is a ferromagnetic material, induction heating can be used to form a bond. The bond formed provides a compressive joint which enables the fiber to be hermetically fixed in position.

Glass fiber fixative and fixing process

A glass composition for a seal consists essentially of 70-75 wt % of PbO, 3-7 wt % of PbF , 5-8 wt % of Bi O , 5-7 wt % of B  , 2-5 wt % of ZnO, 1-3 wt % of Fe O , 0-2 wt % of CuO, 0-2% of TeO , and a trace <0.2% of MnO , the composition having a flow temperature of <350&deg; C. Such seals can be flowed at low temperatures, using different and less environmentally damaging constituents to those used before. Damage to temperature sensitive materials near the seals, can be reduced. Low flow temperatures can be achieved without excessive degradation of properties such as low viscosity, low expansion coefficient, good adhesion to glass and metals, low permeability of air, good long term hydrolytic stability. A filler such as a ceramic powder, is added to match the temperature expansion coefficient to the materials being sealed. It can be used to fix silica fiber into electro-optic devices to achieve hermetic joints with high mechanical stability.

Growing community of inventors

Paignton, United Kingdom

Timothy J Durrant