This specification covers type 58 borosilicate sealing glass for use in electronic applications. The glass material shall conform to the chemical composition requirements prescribed. The material shall conform to the physical and electrical properties prescribed. The glass shall have a finish that ensures smooth, even surfaces and freedom from cracks, checks, bubbles, and other flaws of a character detrimental to the strength or life of the component or device for which its use is intended. The softening point and annealing point shall be tested to meet the requirements prescribed. The thermal expansion coefficient of the glass material shall be determined using the required procedure. The contracting coefficient of the glass material shall be tested to meet the requirements prescribed. The thermal contraction match between the glass and a sealing alloy may be determined by preparing and testing an assembly to meet the requirements prescribed.

1.1 This specification covers Type 58 borosilicate sealing glass for use in electronic applications.

Note 1—This specification is primarily intended to consider glass as most generally used, that is, glass in its transparent form as normally encountered in fabricating electronic devices. X1.3 refers to a sealing alloy that is compatible with this glass. Type 58 glass in other forms such as powdered, crushed, sintered, fibrous, etc., are excluded. The requirements of this specification, as applied to these forms, must be established in the raw glass prior to its conversion.