MIL-HDBK-280 1985 Edition, February 19, 1985
NEUTRON HARDNESS ASSURANCE GUIDELINES FOR SEMICON
Includes all amendments and changes through Cancellation Notice 1, December 20, 2001
Additional Comments: CNCL S/S BY MIL-HDBK-814
Hardness assurance (HA) for electronic piece parts is the application of methods and procedures during the procurement of an electronic piece part to ensure that the radiation response of the purchased part is within known and acceptable limits. The scope of this handbook is limited to hardness assurance with respect to neutron radiation effects on piece-part semiconductor devices and microcircuits. An assumption underlying the handbook is that the neutron environment which the system must survive is specified.
Systems which must operate in a nuclear environment must be capable of nuclear survivability, which means that they shall be able to complete their mission in spite of nuclear radiation induced stresses. Radiation hardening of a system is the process of making sure that a system is designed to survive a specific set of nuclear threats. Hardness assurance (HA) is the application of methods and procedures during production of a system to make certain that it is produced with the hardness level that was designed into it. Although HA is performed during the production phases of a system, experiences has shown that it must be considered during the design phases if a cost effective system is to be obtained.
An important goal of this handbook is to promote the standardization of hardness assurance procedures, so that the benefits of standardization such as, for example, reduced requirements for documentation and for contractual negotiations, can be realized for radiation hardened systems.
This handbook has been written for those who carry out the HA functions but it will also be a valuable guide for the designers of radiation hardened systems who develop the hardness assurance design documentation (HADD). The designers must keep the costs of HA in mind as they design the system. The HA personnel must on the other hand utilize the requirements and documentation established during design in order to carry out the HA activities. Any HA requirements not provided during the design hardening phase must be determined by the HA personnel on the basis of the design guidelines defined in Paragraph 5.1.
The subject of system hardness assurance is sufficiently complex and dependent upon the details of system mission requirements, time schedules, and costs that substantial standardization of system hardness assurance procedures is clearly a much more difficult problem than it is for piece parts hardness assurance. For this reason this handbook mainly discusses piece part hardness assurance methods and discusses system hardness assurance topics only as they are necessary to complete the discussion for piece parts. Thus the discussion will deal in detail with methods for characterizing the radiation responses of parts and for categorizing them according to certain criteria which will determine how stringently controls will need to be applied during part procurement. Specific activities and functions which may be significantly different for different systems and for different contracting organizations will not be discussed in detail.
Neutron effects are rarely the only consideration for system survivability. Additional effects such as aging, other nuclear radiation effects (for example, total ionizing dose, electromagnetic pulse (EMP), etc.) and other environmental effects (for example, temperature) can also cause system failure. These additional effects impact on the neutron requirements since they often determine how stringent the neutron requirements must be. For example, a part which is highly likely to fail due to temperature variations may require an extra low failure probability from becoming too large. On the other hand, if the part is insensitive to temperature variations, a higher failure probability specifically due to the neutron damage mechanisms may be tolerated. The problem of assigning acceptable risks to other failure mechanisms (reliability budget considerations), and their impact on the neutron hardening considerations are beyond the scope of this document. However, more information and an example of system failure budget considerations may be found in reference 1.