SIST ISO 18927:2011

INTERNATIONAL ISO
STANDARD 18927
Second edition
2008-10-15
Imaging materials — Recordable compact
disc systems — Method for estimating
the life expectancy based on the effects
of temperature and relative humidity
Matériaux pour image — Systèmes de CD enregistrables — Méthode
d'estimation de l'espérance de vie basée sur les effets de la
température et de l'humidité relative

Reference number
©
ISO 2008
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ii © ISO 2008 – All rights reserved

Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Purpose and assumptions.4
4.1 Purpose .4
4.2 Assumptions.4
5 Measurements .4
5.1 Summary .4
5.2 Block error rate (BLER).5
5.3 Test equipment .5
5.4 Test specimen.5
6 Accelerated stress test plan.6
6.1 General .6
6.2 Stress conditions .7
6.3 Accelerated test cell sample population.10
6.4 Time intervals .10
6.5 Test plan.10
6.6 Measurement conditions .11
7 Data evaluation .11
7.1 Lognormal distribution model.11
7.2 Eyring acceleration model.11
7.3 Acceleration factors .12
7.4 Survivor analysis.12
7.5 Aids.13
8 Disclaimer .13
Annex A (informative) Step analysis outline .14
Annex B (informative) Example of test plan and data analysis.15
Bibliography.27

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 18927 was prepared by Technical Committee ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 18927:2002), of which it constitutes a minor
revision.
The following changes have been made to the first edition:
⎯ modification of definition 3.10 (life expectancy);
⎯ modification of 5.2 on block error rate;
⎯ updating of normative and bibliographical references;
⎯ removal of the original Annex A.
iv © ISO 2008 – All rights reserved

INTERNATIONAL STANDARD ISO 18927:2008(E)

Imaging materials — Recordable compact disc systems —
Method for estimating the life expectancy based on the effects
of temperature and relative humidity
1 Scope
This International Standard specifies a test method for estimating the life expectancy of information stored on
recordable compact disc systems. Only the effects of temperature and relative humidity on the media are
considered.
This International Standard does not cover the effects of light, air pollution, or time-dependent flow
phenomena.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
1)
ISO/IEC 10149 , Information technology — Data interchange on read-only 120 mm optical data disks
(CD-ROM)
IEC 60908:1999, Audio recording — Compact disc digital audio system
Experimental statistics, U.S. National Bureau of Standards Handbook 91, 1963
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
baseline
condition representing the disc at time of manufacture
NOTE This is customarily the initial parameter measurement taken prior to any application of stress. The designation
is usually t = 0 for a stress time equal to zero hours.
3.2
block error rate
BLER
ratio of erroneous blocks to total blocks measured at the input of the first (C1) decoder (before any error
correction is applied)
1) Equivalent to ECMA 130.
NOTE The more commonly reported value for BLER is the number of erroneous blocks per second measured at the
input of the C1-decoder during playback at the standard (1X) data rate.
[IEC 60908:1999]
3.2.1
maximum block error rate
max BLER
maximum BLER measured anywhere on a disc
3.3
compact disc-recordable
CD-R
recordable optical disc in which information can be recorded to certain areas in compact disc format
NOTE 1 Information can be recorded once and read many times.
NOTE 2 The term “compact disc-write once” (CD-WO) has also been used to describe this type of disc.
3.4
cumulative distribution function
F()t
probability that a random unit drawn from the population fails by time t, or the fraction of all units in the
population which fails by time t
3.4.1
lognormal cumulative distribution function
F()t
cumulative distribution function in which the logarithm of the relevant parameter, in this International Standard
the disc lifetime, has a normal distribution and is defined by the following equation:
t ln( x)−µ
1l
−()
2 σ
l
F()tx= e d
∫
σ x
2π
l
where
t is the time;
x is a variable representing disc lifetime;
σ is the log standard deviation;
l
µ is the log mean;
l
ln(x) is the natural logarithm of x
µ
NOTE When t = e , the lognormal cumulative distribution function evaluates to 0,5. In other words, the model
predicts that half the samples have failed at that time.
3.5
disc-at-once recording
method of recording a CD-R disc whereby the entire CD is recorded in one pass without turning off the laser
3.6
end-of-life
occurrence of any loss of information
2 © ISO 2008 – All rights reserved

3.7
extended-term storage conditions
storage conditions suitable for the preservation of recorded information having permanent value
3.8
glass transition
reversible change in an amorphous polymer from, or to, a viscous or rubber condition to, or from, a hard and
relatively brittle one
3.8.1
glass transition temperature
T
g
approximate mid-point of the temperature range over which glass transition takes place
NOTE 1 T can be determined readily only by observing the temperature at which a significant change takes place in a
g
specific electrical, mechanical, or other physical property.
NOTE 2 T can also be sensitive to the moisture content of the polymer.
g
3.9
information
signal or image recorded using the system
3.10
life expectancy
LE
length of time that information is predicted to be acceptable in a system after dark storage at 23 °C and 50 %
relative humidity (RH)
3.10.1
standardized life expectancy
SLE
minimum life span, predicted with 95 % confidence, of 95 % of the product stored at a temperature not
exceeding 25 °C and a relative humidity (RH) not exceeding 50 % RH
3.11
retrievability
ability to access information as recorded
3.12
stress
experimental variable to which the specimen is exposed for the duration of the test interval
NOTE In this International Standard, the stress variables are confined to temperature and relative humidity.
3.13
survivor function
R()t
probability that a random unit drawn from the population survives at least time t, or the fraction of all units in
the population which survive at least time t
NOTE R()tF=−1 (t).
3.14
system
combination of material, hardware, software and documentation necessary for recording and/or retrieving
information
3.15
test cell
device that controls the stress to which the specimen is exposed
3.16
track-at-once recording
method of recording a CD-R disc whereby each track is recorded individually with 150 empty sectors
immediately preceding it and two run-out sectors immediately following
3.17
uncorrectable error
error in the playback data that is not correctable by the cross interleave Reed-Solomon code defined in
IEC 60908 as implemented in a system
4 Purpose and assumptions
4.1 Purpose
The purpose of this International Standard is to establish a methodology for estimating the life expectancy of
information stored on recordable compact disc systems. This methodology provides a technically and
statistically sound procedure for obtaining and evaluating accelerated test data.
The methodology deals only with the effects of temperature and humidity on the retrievability of stored
information. For this reason, this International Standard is primarily directed to those storage applications, e.g.
libraries and archives, in which exposure to other influences potentially detrimental to information life
expectan
...