scope:

Systems that must operate in a radiation environment have to be designed to be survivable (hard) to radiation stress levels specified for them. In addition to design hardening, a Hardness Assurance (HA) program must also be developed during the system design phase for implementation in the production phase. The HA program consists of the production controls and tests which assure that each end product, i.e., delivered system, meets the hardened design specifications and requirements. This handbook is a revision and combination of the earlier MIL-HDBK-279 (see 6.1) and MIL-HDBK-280 (see 6.2) which in turn were the results of earlier work performed under the auspices of the Defense Nuclear Agency ((DNA) see 6.3 and 6.4).

Many methods and techniques may be employed at the various electronics design levels (system, subsystem, module and part) to achieve system survivability. This handbook provides HA techniques and procedures applicable to neutron fluence and ionizing radiation dose permanent damage effects on electronic pieceparts. (This damage is considered permanent even though some annealing may occur.) Sufficient information is provided to relate part level HA to the overall system's HA program. Complete procedures are provided for the application of two piecepart HA methods, the Design Margin Breakpoint (DMBP) method and the Parts Categorization Criterion (PCC) method. The DMBP method does not provide a mathematical basis from which statistical survivability inferences may be drawn for the individual part types. There is also a risk involved in that the device response dispersion is not taken into account. The PCC method is mathematically rigorous and applies single-sided cumulative distribution statistics with relationship to survivability requirements and sample size. The PCC method is somewhat more difficult to apply than the DMBP method, but is applicable to any system and provides a sound statistical basis for piecepart survivability estimates. Both methods apply defined design margins and categorization procedures for piecepart control and testing.

The intent of this document is to provide the methodology and procedures applicable to the DMBP and PCC electronic pieceparts radiation HA methods. Both methods have been applied to systems currently in production or in the DoD inventory. An important goal of this handbook is to promote the standardization of HA procedures. Standardization is of great benefit in establishing program adequacy and reducing costs in that new and untried procedures need not be developed for each systems program. Having a basic, standardized program is also important to maintenance organizations where numerous systems must be maintained over their operational lifetimes.

This document addresses the piecepart level system engineering approach to the implementation of an HA program applicable to both neutron and ionizing radiation (ionizing dose) permanent damage derived from nuclear weapon or natural space environments. Recommendations are included for systems with low to moderate requirements (DMBP method) and for moderate to severe requirements (PCC method). A system of parts categorization based on design margin is presented which provides consistency in parts qualification procedures and control requirements. Information is provided on sampling and sample sizes, test facilities, qualification and lot acceptance testing, and documentation requirements. Recommendations are made for the use of pieceparts available under the Government sponsored Radiation Hardness Assured (RHA) device program. Information is also included on peripheral subject matter that is necessary or helpful to an understanding of these guidelines.

This handbook is directed primarily toward the systems contractors, Systems Program Offices (SPOs) and Program Executive Offices (PEOs) that are responsible for developing electronic equipment which is hardened to specified radiation environments and has a corresponding HA program.

These guidelines address only permanent or semipermanent damage to electronic pieceparts resulting from ionizing radiation dose or neutron displacement damage. It does not deal with transient effects occurring as a result of highly ionizing, short duration pulses of gamma or x rays, (i.e., prompt dose rate effects).

It should be noted that the DMBP method described herein, though initially based on statistical considerations, is not mathematically rigorous. The method is related to the mean of a sample distribution rather than the dispersion or standard deviation of the particular test sample. Though the recommended breakpoints are generally considered conservative, a risk factor must be assumed since the actual deviation about the mean is not taken into consideration for each device type. The method, however, is particularly useful when the specification requirements (radiation stress levels and survivability and confidence factors) are moderate.