MIL-HBDK-217 Quality Levels
The quality screening level used in the manufacturing of the device. The choices for the quality level of a device are based on the model. In the specification, you can find the screening levels and Pi Q values assigned to each device. For example, the following table describes the accepted quality levels for microcircuits in MIL-HDBK-217 FN1. For more information, see Pi Q Values.
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Level
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Description
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S
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1. Procured in full accordance with MIL-M-38510, Class S requirements.
2. Procured in full accordance with MIL-I-38535 and Appendix B thereto (Class U).
3. Hybrids:- Procured to Class S requirements (Quality Level K) of MIL-H-38534.
The Pi Q value for a Microcircuit screened to an S quality level is 0.25.
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B
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1. Procured in full accordance with MIL-M-38510, Class B requirements.
2. Procured in full accordance with MIL-I-38535, (Class Q).
3. Hybrids:— Procured to Class B requirements (Quality Level H) of MIL-H-38534.
The Pi Q value for a Microcircuit screened to a B quality level is 1.0.
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B-1
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Fully compliant with all requirements of paragraph 1.2.1 of MIL-STD-883 and procured to a MIL drawing, DESC drawing, or other government approved documentation. (Does not include hybrids.) For hybrids, use custom screening factors.
The Pi Q value for a Microcircuit screened to a B-1 quality level is 2.0.
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Other devices have different quality levels and Pi Q values. To review the accepted quality levels, descriptions, and Pi Q values, see the specification in use.
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When Mil-Spec parts are purchased, the quality levels of the parts are known. Because of the great improvement in the quality of commercial parts over the past 10 to 15 years, many companies now use commercial parts. Because MIL-HDBK-217 models have different quality scales for different part types, determining the quality levels of commercial parts is not as easy.
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