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Level
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Description
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0
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The level to assign to devices considered to be commercial-grade or reengineered/remanufactured components.
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I
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The level to assign to commercial-grade devices that are procured and used without thorough device qualification or lot-to-lot controls by the equipment manufacturer. The following requirements must be met:
• Steps must have been taken to ensure that the components are compatible with the design application and the manufacturing process; and
• An effective feedback and corrective action program must be in place to identify and resolve problems quickly in manufacture in the field.
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II
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The level assigned to devices that meet the requirements of Quality Level I plus the following:
• Purchase specifications must explicitly identify important characteristics (electrical, mechanical, thermal) and acceptable quality levels (such as AQLs, DPMs) for lot control;
• Devices and vendors must be qualified and identified on approved parts/vendor lists (device qualification must include appropriate life and endurance tests);
• Lot-to-lot controls, either by the equipment manufacturer or the device manufacturer, must be in place at adequate AQLs/DPMs to ensure consistent quality.
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III
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The level assigned to devices that meet the requirements of Quality Levels I and II plus the following:
• Devices must be requalified periodically;
• Lot-to-lot controls must include 100% screening (temperature cycling and burn-in) which, if the results warrant it, may be reduced to a “reliability audit” (such as on a sample basis) or to an acceptable “reliability monitor” with demonstrated and acceptable cumulative early failure values out to 10,000;
• Where burn-in screening is used, the percent defective allowed (PDA) should be specified; and
• An ongoing, continuous reliability improvement program must be implemented by both the device and equipment manufacturer.
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