1.1 This practice covers the preparation and testing of a reference glass-metal sandwich seal for determining stress in the glass or for determining the degree of thermal expansion (or contraction) mismatch between the glass and metal. Tests are in accordance with Test Method F218 (Section 2).

1.2 This practice applies to all glass and metal (or alloy) combinations normally sealed together in the production of electronic components.

1.3 The practical limit of the test in deriving mismatch is approximately 300 ppm, above which the glass is likely to fracture.

1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.