ASTM F1263-11(2019)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F1263 − 11 (Reapproved 2019)
Standard Guide for
Analysis of Overtest Data in Radiation Testing of Electronic
Parts
This standard is issued under the fixed designation F1263; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 rejection confidence—the probability, R, that a lot will
be rejected based on destructive tests of selected specimens if
1.1 This guide covers the use of overtesting in order to
more than a specified fraction, P, of the parts in the lot will fail
reduce the required number of parts that must be tested to meet
in actual service.
a given quality acceptance standard. Overtesting is testing a
sample number of parts at a stress level higher than their 3.1.3 Discussion of Preceding Terms—Strictly speaking,
specification stress in order to reduce the amount of necessary most lot acceptance tests (be they testing by attributes or
data taking. This guide discusses when and how overtesting variables) do not guarantee survivability, but rather that infe-
may be applied to forming probabilistic estimates for the rior lots, where the survival probability of the parts is less than
survival of electronic piece parts subjected to radiation stress. probability, P, will be rejected with confidence, C. In order to
Some knowledge of the probability distribution governing the infer a true confidence, it would require a Bayes Theorem
stress-to-failure of the parts is necessary, although exact calculation. In many cases, the distinction between confidence
knowledge may be replaced by over-conservative estimates of and rejection confidence is of little practical importance.
this distribution. However, in other cases (typically when a large number of lots
are rejected) the distinction between these two kinds of
1.2 This international standard was developed in accor-
confidence can be significant. The formulas given in this guide
dance with internationally recognized principles on standard-
apply whether one is dealing with confidence or rejection
ization established in the Decision on Principles for the
confidence.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
4. Summary of Guide
Barriers to Trade (TBT) Committee.
4.1 This guide is intended to primarily apply to sampling by
2. Referenced Documents
attribute plans typified by Lot Tolerance Percent Defective
(LTPD) tables given in MIL-PRF 38535 and MIL-PRF 19500,
2.1 Military Standards:
and contains the following:
MIL-PRF 19500 Semiconductor Devices, General Specifi-
4.1.1 An equation for estimating the effectiveness of over-
cations for
testing in terms of increased probability of survival,
MIL-PRF 38535 Integrated Circuits (Microcircuit Manufac-
4.1.2 An equation for the required amount of overtesting
turing)
given a necessary survival probability, and
3. Terminology 4.1.3 Cautions and limitations on the method.
3.1 Definitions of Terms Specific to This Standard:
5. Significance and Use
3.1.1 confidence—the probability, C, that at least a fraction,
5.1 Overtesting should be done when (a) testing by vari-
P, of the electronic parts from a test lot will survive in actual
ables is impractical because of time and cost considerations or
service; since radiation testing of electronic parts is generally
because the probability distribution of stress to failure cannot
destructive, this probability must be calculated from tests on
be estimated with sufficient accuracy, and (b) an unrealistically
selected specimens from the lot.
large number of parts would have to be tested at the specifi-
cation stress for the necessary confidence and survival prob-
This guide is under the jurisdiction of ASTM Committee E10 on Nuclear
ability.
Technology and Applications and is the direct responsibility of Subcommittee
E10.07 on Radiation Dosimetry for Radiation Effects on Materials and Devices.
6. Interferences
Current edition approved Dec. 1, 2019. Published December 2019. Originally
approved in 1989. Last previous edition approved in 2011 as F1263 – 11. DOI:
6.1 Probability Distributions—In overtesting, a knowledge
10.1520/F1263-11R19.
of the probability distribution governing stress to failure is
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. required, though it need not be specified with the same
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F1263 − 11 (2019)
5 ,6
accuracy necessary for testing by variables. For bipolar tran- 7.2 For neutrons, 0.5 is a good estimate of σ (max).
ln
sistors exposed to neutron radiation, the failure mechanism is
7.2.1 Example—Suppose bipolar transistors are tested at a
usually gain degradation and the stress to failure is known to
neutron fluence three times the specification fluence and it is
follow a lognormal distribution. For bipolar transistors ex-
determined that with 90 % confidence, at least 80 % of the
posed to total dose the use of the lognormal distribution is also
transistors will survive the overtest fluence. Then from Eq 1, at
fairly accurate. For more complex electronics and other kinds
the specification fluence, with 90 % confidence, the survival
of radiation stress, the lognormal distribution is widely used in
probability is as follows:
estimating the failure probabilities of electronic piece parts,
¯
P 5 F@F P 1ln 3 /0.5# 5 F 0.8412.20 5 F 3.04 5 0.999,
~ ! ~ ! @ # @ #
S T
and therefore this standard governs the use of a lognormal
distribution. However, caution should be exercised when the
where we used the following facts governing the normal
probability distribution of stress to failure is not well estab-
distribution:
lished. Nevertheless, even if the lognormal distribution does
Standard probability tables such as those shown in M.G.
not strictly apply, the equations given in Section 7 will hold as
Natrella, “Experimental Stat
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