This tool implements the MIL-HDBK-217F, Notice 2 (Reliability Prediction of Electronic Equipment), parts count reliability prediction procedure (ref. 1). Application notes are as follows:1. The part quantity column (last column) defaults to 1 if nothing is entered into this field.2. Selecting defaults for part quality and/or environmental factors will override all entries in the larger input matrix for these factors. Selecting the "industrial" default for part quality will default the microcircuitquality levels to a value of 3 and will select one level better than worse case for all other part types. See references 3 and 4 for other industry standard approaches.3. The part quality factor selected (third input column) must be consistent with the part type selected in the second column.4. If anything is entered into the user defined column (e.g., a part number), then this column will appear in the output, otherwise it is omitted.5. The first row is used for column labels initially; however, this row is available for use by deleting/overriding the labels.6. The tool simplifies the microcircuit portion of the MIL-HDBK-217 parts count method by defaulting the learning factor to 1.0 and not providing the quality factor calculations for custom part screening regimes, as both of these arerarely used in practice. If needed, export to Excel to perform these custom calculations.7. Most browsers remember user input settings when the back button is used allowing easy modification of inputs; however, this may not be true with some versions of Internet Explorer.8. The "omit part type reference numbers" checkbox eliminates the prefix numbers (1-208) shown in the second column from the output results.9. See references 3 - 4 for ANSI/VITA recommendations on more favorable part quality factors, essentially 0.1 for chip resistors and capacitors, and a value of 1.0 for most other part types. Export to Excel to make these adjustments. 10. MIL-HDBK-217F, Notice 2, Environmental Descriptions and Assumed Default Operating Temperatures11. Reliability Adjustment Factors for Electronic Equipment
This new specification provides standard defaults and methods to adjust the models in Mil-hdbk-217-F2 (M217F2). This is not a revision of M217F2 but a standardization of the inputs to the M217F2 calculations to give more consistent results.When planning military or high reliability applications, knowledge is needed regarding the potential life of electronic components involved in that system. More and more of the electronic components used in such systems are Commercial Off-The-Shelf (COTS) items. As such, the military program has very little control of the design, development, and availability of these modules. A reliable method to predict the failure rate of these systems is essential for planning sparing. Reliability is considered to be an important aspect of any electronic system, especially when utilizing COTS products. Reliability assurance is a very critical element in the acquisition and life-cycle management of military systems and especially challenging with the broad use of COTS items. In 1961, the first edition of M217F2 was published, providing a basic failure rate prediction methodology that is still in widespread use today, despite problems, limitations and inaccuracies that have been identified with the M217F2 methodology. Manufacturers and electronic reliability engineers use different methods to adjust the models in M217F2 for newer technologies, use different defaults for unknown stress conditions, and make differing assumptions of quality and complexity factors for COTS items. These differing methods yield results that are not comparable. The new standard is intended to provide a standard method for reliability engineers to perform failure rate predictions for COTS items used in military or high reliability applications.
Reliability engineers in the government and industry sectors continue to use M217F2 to perform failure rate predictions. Because M217F2 has not been updated recently, there are many new developments in electronics that are not accounted for, thus, reliability engineers must make changes to the M217F2 methodology to make their failure rate predictions more realistic. This specification provides a standard method of performing reliability predictions on COTS modules using M217F2. This is not a revision or a modification of M217F2 but a standardization of the inputs to the M217F2 calculations to give more consistent MTBF numbers. This specification will assist the user in determining the credibility of published failure rate information and outline the techniques necessary for developing and applying this information to military or high reliability applications. 2b1af7f3a8