Porosity and glass sputtering in the sealing process of glass to metal

The effects of sealing atmosphere,sealing temperature,sealing time,oxides' type and thickness on porosity and glass sputtering were investigated by measuring the porosity and the maximum diameter of gas bubbles in the glass insulator and observing the glass sputtering state on the surface of kovar alloy under various process conditions.It is indicated that there is a relationship between the porosity of the glass insulator and the glass sputtering grade on the surface of Kovar alloy.The chemical reaction between Fe₃O₄ on the surface of Kovar alloy and SiO₂ in glass is an important source of porosity in the glass insulator,and it is also an influence factor of glass sputtering.Sealing atmosphere and oxides' thickness are the most important factors for porosity and glass sputtering.The recommended conditions are that FeO is formed on the surface of Kovar alloy and its thickness is about 1 μm,the sealing temperature is about from 950 to 980℃ and the sealing time is from 30 to 40 min in the real production atmosphere.