Polycrystalline insulating material seals between spaced members such as a terminal pin and a ferrule

In combination,

• a first member,
• a second member spaced from the first member, and
• electrically insulating material hermetically sealing the first and second members and including the following in its original composition:
• a first flux consisting of lead oxide, boric oxide and silicon dioxide and having a first melting temperature, and
• a second flux consisting of lead oxide and boric oxide and having a higher melting temperature than the first flux,
• a polycrystalline stuffing including oxides of zirconium and zinc and silicon and having properties of providing in a random distribution first crystals having a first size and shape and second crystals having a second size and shape different from the first size and shape, the first and second crystals being primarily disposed in a layer adjacent to at least a particular one of the first and second members to provide a flexibility resisting thermal and mechanical shock, the first and second members and the first and second fluxes and the polycrystalline stuffing being hermetically sealed by the application of heat at a temperature less than 1300.degree. F. for a limited period of time and by subsequent cooling in air.

In combination in a heart pacemaker,

• a terminal pin made from a noble metal,
• a ferrule made from a material selected from the group consisting of titanium and an alloy of titanium, and
• a material hermetically sealing the terminal pin and the ferrule and having insulating properties,
• the insulating material being partially amorphous and partially crystalline and being particularly crystalline at the boundary with the ferrule,
• oxides of lead, boron and silicon being included in the insulating material in a first flux and oxides of lead and boron being included in the insulating material in a second flux having a higher melting temperature than the first flux and oxides of lead, zinc, antimony and zirconium being included in the insulating material in a crystalline stuffing and the first flux being included in the insulating material with a weight of approximately 15% to 25% and the second flux being included in the insulating material with a weight of approximately 40% to 55% and the crystalline stuffing constituting the remainder of the insulating material.

In combination,

• a first member,
• a second member spaced from the first member, and
• an insulating material disposed between the first and second members and hermetically sealing the first and second members and formed from:
• (a) a first flux consisting of lead oxide, silicon dioxide and boric ocide and having a first melting temperature,
• (b) a second flux consisting of lead oxide and boric oxide and having a higher melting temperature than the first flux, and
• (c) a crystalline stuffing including oxides of zirconium and zinc and silicon and having properties of providing crystals in a layer adjacent to at least a particular one of the first and second members,
• the insulating material being formed at temperatures below about 1300.degree. F. and the first member being made form a noble metal and the second member being made from a material selected from the group consisting of titanium and a titanium alloy and the insulating material being provided with a coefficient of thermal expansion slightly greater than that of the second member.

In combination,

• a first member,
• a second member separated from the first member, and
• insulating material hermetically sealing the first and second members and having self-correcting properties of providing a hermetic seal between the first and second members by the application of heat to the combination of the first and second members and the insulating material when a hermetic seal does not exist,
• the insulating material being primarily polycrystalline at the boundary between the second member and the insulating material and the polycrystals having a random orientation of different sizes and shapes to provide a flexibility in withstanding thermal and mechanical shocks and the insulating material being progressively amorphous from the boundary between the second member and the insulating material,
• the surface of the first member being etched and the insulating material being locked in the etched surface of the first member,
• the insulating material including first and second fluxes each including boric oxide, the first and second fluxes forming eutectics to effectively decrease the melting temperature of the boric oxide in the fluxes.