ASTM E1249-00

1.1 This practice covers recommended procedures for the use of dosimeters, such as thermoluminescent dosimeters (TLD's), to determine the absorbed dose in a region of interest within an electronic device irradiated using a Co-60 source. Co-60 sources are commonly used for the absorbed dose testing of silicon electronic devices.

1.2 The principal potential error for the measurement of absorbed dose in electronic devices arises from non-equilibrium energy deposition effects in the vicinity of material interfaces.

1.3 Information is given about absorbed-dose enhancement effects in the vicinity of material interfaces. The sensitivity of such effects to low energy components in the Co-60 photon energy spectrum is emphasized.

1.4 A brief description is given of typical Co-60 sources with special emphasis on the presence of low energy components in the photon energy spectrum output from such sources.

1.5 Procedures are given for minimizing the low energy components of the photon energy spectrum from Co-60 sources, using filtration. The use of a filter box to achieve such filtration is recommended.

1.6 Information is given on absorbed-dose enhancement effects that are dependent on the device orientation with respect to the Co-60 source.

1.7 The use of spectrum filtration and appropriate device orientation provides a radiation environment whereby the absorbed dose in the sensitive region of an electronic device can be calculated within defined error limits without detailed knowledge of either the device structure or of the photon energy spectrum of the source, and hence, without knowing the details of the absorbed-dose enhancement effects.

1.8 The recommendations of this practice are primarily applicable to piece-part testing of electronic devices. Electronic circuit board and electronic system testing may introduce problems that are not adequately treated by the methods recommended here.

1.9 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.