IEC 62572-3:2011

IEC 62572-3 ®
Edition 1.0 2011-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Fibre optic active components and devices – Reliability standards –
Part 3: Laser modules used for telecommunication

Composants et dispositifs actifs en fibres optiques – Normes de fiabilité –
Partie 3: Modules laser utilisés pour les télécommunications

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IEC 62572-3 ®
Edition 1.0 2011-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Fibre optic active components and devices – Reliability standards –
Part 3: Laser modules used for telecommunication

Composants et dispositifs actifs en fibres optiques – Normes de fiabilité –
Partie 3: Modules laser utilisés pour les télécommunications

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX R
ICS 31.260; 33.180 ISBN 978-2-88912-726-9

– 2 – 62572-3 © IEC:2011
CONTENTS
FOREWORD . 3

INTRODUCTION . 5

1 Scope . 6

2 Normative references . 6

3 Terms, definitions and symbols . 6

3.1 Terms and definitions . 6

3.2 Symbols . 7

4 Laser reliability and quality assurance procedure . 8
4.1 Demonstration of product quality . 8
4.2 Testing responsibilities . 8
4.2.1 General . 8
4.2.2 Recommendation applicable to laser customer/system supplier . 8
4.2.3 Recommendation applicable to system operator . 8
4.3 Quality improvement programmes (QIPs) . 8
5 Tests . 9
5.1 General . 9
5.2 Structural similarity . 9
5.3 Burn-in and screening (when applicable in the specification) . 9
6 Activities. 13
6.1 Analysis of reliability results . 13
6.2 Technical visits to LMMs . 13
6.3 Design/process changes . 14
6.4 Deliveries . 14
6.5 Supplier documentation . 14
Annex A (informative) Guidance on testing in Table 1 and Table 2 . 15

Table 1 – Initial qualification . 10
Table 2 – Maintenance of qualification . 12
Table 3 – Performance for laser module reliability parameters . 13
Table A.1 – Recommended life test conditions for laser modules containing Peltier
coolers . 15

Table A.2 – Recommended life test conditions for uncooled laser modules . 16
Table A.3 – Recommended laser diode life test conditions . 16
Table A.4 – Recommended photodiode life test conditions . 17

62572-3 © IEC:2011 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
FIBRE OPTIC ACTIVE COMPONENTS AND DEVICES –

RELIABILITY STANDARDS –
Part 3: Laser modules used for telecommunication

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62572-3 has been prepared by subcommittee 86C: Fibre optic
systems and active devices of IEC technical committee 86: Fibre optics.
The text of this standard is based on the following documents:
FDIS Report on voting
86C/1022/FDIS 86C/1035/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 62572-3 © IEC:2011
The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be

• reconfirmed,
• withdrawn,
• replaced by a revised edition, or

• amended.
62572-3 © IEC:2011 – 5 –
INTRODUCTION
The laser modules covered by this International Standard are purchased by system suppliers

(SS) to be inserted in equipment which in turn are supplied/sold to a system operator (SO) or

a network operator (see definitions in Clause 3).

For the system operator to act as an informed buyer, knowledge of the potential risks posed

by the use of critical components is required.

Optoelectronic component technology is continuing to develop. Consequently, during product

development phases, many failure mechanisms in laser modules have been identified. These

failure mechanisms, if undetected, could result in very short laser lifetime in system use.

– 6 – 62572-3 © IEC:2011
FIBRE OPTIC ACTIVE COMPONENTS AND DEVICES –

RELIABILITY STANDARDS –
Part 3: Laser modules used for telecommunication

1 Scope
This part of IEC 62572 deals with reliability assessment of laser modules used for
telecommunication.
The aim of this standard is:
– to establish a standard method of assessing the reliability of laser modules in order to
minimize risks and to promote product development and reliability;
– to establish means by which the distribution of failures with time can be determined. This
should enable the determination of equipment failure rates for specified end of life criteria.
In addition, guidance is given in IEC/TR 62752-2:2008.
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.
IEC 60068-2-1, Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-14, Environmental testing – Part 2-14: Tests – Test N: Change of temperature
IEC 60747-1, Semiconductor devices – Part 1: General
IEC 60749-1, Semiconductor devices – Mechanical and climatic test methods – Part 1:
General
IEC/TR 62572-2:2008, Fibre optic active components and devices – Reliability standards –
Part 2: Laser module degradation

ISO 9001, Quality management and quality assurance standards
MIL-STD-883, Test methods and Procedures for Microelectronics
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document the following definitions apply.
3.1.1
laser module
packaged assembly containing a laser diode and photodiode

62572-3 © IEC:2011 – 7 –
NOTE The module may also include a cooler and temperature sensor to enable laser temperature to be controlled

and monitored. The optical output is normally via an optical fibre pigtail.

3.1.2
submount
substrate upon which a laser diode or photodiode may be mounted for assembly into the laser

module
NOTE Components on submounts are also subject to qualification testing.

3.1.3
laser module manufacturer
LMM
manufacturer of laser modules who provides devices meeting the requirements of the relevant
specification and the customer’s reliability requirements
3.1.4
system supplier
SS
manufacturer of telecommunications/data transmission equipment containing optoelectronic
semiconductor lasers, i.e. laser module customer
3.1.5
system operator
SO
network operator of telecommunications/data transmission equipment containing opto-
electronic semiconductor lasers in the transmission path
NOTE The system may also be part of other more extensive systems, for example telecommunications, rail, road
vehicles, aerospace or weapons.
3.1.6
capability qualifying components
CQC
components selected to represent critical stages of the process and limiting or boundary
characteristics of mechanical and electro-optic design
NOTE Such components should aid the identification of end product failure mechanisms to enable the
determination of activation energies.
3.2 Symbols
minimum storage temperature
T
A
T  maximum storage temperature
B
T module case temperature
c
T  submount temperature
s
T recommended submount temperature
s nom
T module minimum operating temperature
op min
T module maximum operating temperature
op max
T module minimum storage temperature
stg min
T module maximum storage temperature
stg max
Qc      test for gross leak detection
Qk      test for fine leak detection
p       periodicity (in months)
n      sample size
– 8 – 62572-3 © IEC:2011
4 Laser reliability and quality assurance procedure

4.1 Demonstration of product quality

This standard (where required by the specification) gives the minimum mandatory

requirements and is part of a total laser reliability and quality assurance procedure adopted

by the laser module manufacture.

It also gives guidance on the activities of the system supplier, and the system operator as well

as feedback of field performance, the laser module manufacturer and the system supplier.

The laser module manufacturer shall be able to demonstrate, by means of qualification
approval of devices, technology approval or capability approval of the manufacturing process:
a) a documented and audited manufacturing process including the qualification of purchased
components in accordance with ISO 9001;
b) a performance qualification programme, including for example, accelerated life testing,
burn-in and screening of components and modules;
c) a qualification maintenance programme to ensure continuity of reliability performance;
d) a procedure to feedback reliability issues to development and production.
4.2 Testing responsibilities
4.2.1 General
The testing detailed in Tables 1 and 2 is to be performed by the laser module manufacturer
and component suppliers (where applicable). Additional testing may be specified in the
specification.
4.2.2 Recommendation applicable to laser customer/system supplier
The system supplier is recommended to have a programme to analyse and verify the results
including failure analysis. This programme includes an independent life test of fully packaged
laser modules, see Table 2, Test 1 and/or Test 2 and 3 and/or Test 5 (sample size >10 per
test).
4.2.3 Recommendation applicable to system operator
The system operator is recommended to have a programme to monitor and report field failure
rates in sufficient detail to enable system supplier and laser module manufacturer to initiate
any necessary corrective actions at an early stage in the lifetime of a product.

Suppliers may have different approaches (i.e. to reliability concepts) during the development
of product maturity and resource limitations may dictate testing strategies.
Alternative tests and activities to those specified are permitted provided the LMM/SS/SO can
show intent to remove end-product failures and the associated failure mechanisms. However,
this will require significant data to substantiate compliance.
4.3 Quality improvement programmes (QIPs)
Quality improvement programmes (QIPs) shall be initiated with component suppliers and
customers (SOs, SSs and LMMs) to address non-compliances (including quality and reliability
problems identified during subsequent service life of the laser). The correction of non-
compliances and subsequent QIPs are a required strategy to minimize reliability risks. The
operation of QIPs should be stated in the quality approval (QA) generic and capability
approval documents.
62572-3 © IEC:2011 – 9 –
5 Tests
5.1 General
The tests described in Tables 1 and 2 are designed to accelerate the main failure

mechanisms known to be reliability hazards in laser modules (see IEC/TR 62752-2:2008).

Where appropriate, the CQC shall demonstrate an ability to reduce end product failure

mechanisms. Final product validation is required to demonstrate that CQCs are operating at

the boundaries of the process or technology. These tests will reduce the risk of unreliable
components entering system use and will enable estimates to be made of the distribution of
laser lifetimes and hence the laser failure rates.

The sample size and level of testing may vary depending on the business volume between the
laser customer/system supplier (SS) and laser module manufacturer (LMM). This information
will be given in the capability approval (CA) document and the specification where appropriate.
NOTE It is essential that the lasers evaluated are entirely representative of standard production devices, and
have passed all the production and/or specified (where applicable in the specification) burn-in and screening
procedures.
Table 1 – Initial qualification
These tests will normally be performed by the laser manufacturer as part of an initial
qualification programme.
Table 2 – Maintenance of qualification
These tests cover periodic monitoring performed on production devices to ensure that the
quality and reliability performance established during initial qualification is maintained or
improved.
5.2 Structural similarity
Where a range of laser modules is produced by a laser manufacturer, there may be some
significant structural similarity between different type codes. A combination of results from
different test programmes, where appropriate, is therefore permitted.
Consideration should be given to the fact that minor differences in technology or processing
can have a major impact on reliability, whilst not being apparent during quality assessment.
Evidence shall be presented which demonstrates that all results are directly relevant.

5.3 Burn-in and screening (when applicable in the specification)
NOTE See IEC/TR 62572-2:2008.
The screening test should be designed by the laser module manufacturer specifically for his
particular technology. Any approach based on similarity to that which is performed by other
manufacturers, is good for comparison purposes, but can be ineffective in achieving the
actual screening goal. This is particularly true for fibre optic components whose technology is
not yet mature and varies significantly from supplier to supplier.
Where a manufacturer can demonstrate component and process stability, screening pro-
cedures may be revised.
– 10 – 62572-3 © IEC:2011
Table 1 – Initial qualification

Test
Test IEC references Conditions n

No.
1 Initial endurance
test
1.1 a) Module with Φ specified, constant power 25
e
thermoelectric Temperature: T = T
c op max
cooler
T = T
s s nom
a
Duration: 5 000 h
1.2 b) Module without
Φ specified, constant power
e
thermoelectric 25
Temperature: T = T
c op max
a
cooler Duration: 5 000 h
1.3 Laser diode Temperature: at least two 200
(submount) test temperatures:
Φ specified, constant power
e
d
T = T   See
s1 s max
d
T = s2 s1
Duration: >5 000 h
1.4 Photodiode  Temperature: at least two 200
(in representative test temperatures:
package)
V or l specified
r r
b d
T = 125 °C min See
s1
d
T = <(T –30 °C) See
s2 s1
Duration: >1 000 h
1.5 High temperature T = T of the cooler 25
stg max
storage of the
Duration: 1 000 h
thermoelectric
cooler
1.6 Power cycle tests Number of cycles: 20 K 25
cooled devices
T = T
c op max
T = T to (T – ∆T )
s c c max
1.7 High temperature T= T of the sensor 25
stg max
storage of the
thermal sensor
2 Fibre test
d
2.1 Fibre proof test Proof test see 10
d
Duration        see
d
Min. bend radius see
2.2 Fibre retention 60749
d
2.2.1 Fibre pull Fibre pull       see 10
d
2.2.2 Side pull Side pull        see

62572-3 © IEC:2011 – 11 –
Table 1 (continued)
Test
Test IEC references Conditions n
No.
c d
3 Change of See and 10
temperature
Rapid change
3.1 60749 Temperature:
of temperature
TA = Tstg min
T = T
B stg max
Number of cycles = 50
3.2 60749 Temperature:
Temperature cycling
60068-2-14 T = T 10
A stg min
T = T
B stg max
°C/min
> 1
Number of cycles = 500
d
4 Sealing 60749 See  10
Test Qk followed by Test Qc
c d
See and and A.6
5 Shock and vibration 60749 See A.7 10
5.1 Shock 500 G, 1 ms with Thermoelectric cooler,

1500 G, 0,5 ms without Thermoelectric
cooler,
6-direction, 5 times each
5.2 Vibration 20 – 2000 Hz, 20 G, 10
3-direction, 30 min each
6 High temperature 60749 Temperature: T = T 10
stg max
storage (not appli-
Duration: >2 000 h
cable if module life
test performed at
(See Table 5, IEC/TR 62752-2:2008)
equivalent case
temperature and
submount
temperature)
7 ESDS, modules 60747-1 Human body model, see A.9 5 per wafer
a) Lasers MIL-STD-883, 5 discharges/test voltage,
Method 3015
b) Photodiodes
charge-discharge cycle > 0,1 s
d
8 Residual gas MIL-STD-883, See 6
analysis Method 1018
See A.10
9 Low temperature 60068-2-1 T = Tstg min 10
storage
Duration: >1 000 h
a
Provided data about the distribution of wear-out lifetime is accumulated with sufficient accuracy. Provisional
approval for product shipment shall be granted at 2 000 h. It is also recommended to continue the test until
accurate extrapolation of lifetime is possible with an upper limit of 10 000 h. Durations up to 5 000 h may be
needed for accurate lifetime prediction.
b
Or as limited by technology.
c
Results from Tests 1.1 and 1.2 shall be supplemented by a laser customer/SS independent test of fully packaged
modules in accordance with Table 2, Test 2 and/or Test 3 (sample size ≥ 10 per test) see also 4.2.
d
Number of samples and conditions shall be determined by a laser customer/SS and LMM.

– 12 – 62572-3 © IEC:2011
Table 2 – Maintenance of qualification

Test
Test IEC references Conditions n p

No.
1 Ongoing reliability test Periodic testing: See NOTES 6

a) Module (cooled) Test 1.1 10

b) Module (uncooled) Test 1.2 10
a
c) Laser diode (submount) Test 1.3   25
a
d) Photodiode Test 1.4   25

2 Temperature cycling 60749 Temperature: 10
60068-2-14 T = T
A stg min
T = T
B stg max
° C/min
> 1
Periodic testing: Number of
cycles = 200 (see NOTE 1 )
3 Sealing 60749 see NOTE 2 10
Test Qk followed by Test Qc
See NOTES and A.6
4 Shock and vibration 60749 See NOTES and A.7
4.1 Shock 500 G, 1 ms with 10
thermoelectric cooler,
1500 G, 0,5 ms without
thermoelectric cooler,
6-direction, 5 times each
20 – 2000 Hz, 20 G,
4.2 Vibration 10
3-direction, 30 min each
5 High temperature 60749 Temperature: 10
storage (not applicable
T = T
stg max
if module life test
performed at equivalent
Duration: >2 000 h
case temperature and
submount temperature) Periodic testing: see NOTES
(See Clause 5 and Table 5,
IEC/TR 62752-2)
6 ESDS, modules Periodic testing: see NOTES 5 per wafer
and A.9
a) Lasers MIL-STD-883,
Method 3015 Human body model
b) Photodiodes
5 discharges/test voltage,
Charge-discharge cycle >
0,1 s
7 Residual gas analysis MIL-STD-883, See NOTE 2 See NOTE 2
Method 1018
Periodic testing: see NOTES
and A.10
a
Out of different wafers.
NOTE 1 Results of Test 2 are supplemented by a laser customer/system supplier (SS) independent test of fully
packaged modules in accordance with Table 2, Test 2 and/or Test 3 and/or Test 5 (sample size ≥ 10 per test). See
also 4.2.
NOTE 2 Number of samples and conditions are determined by a laser customer/SS and LMM.

62572-3 © IEC:2011 – 13 –
6 Activities
6.1 Analysis of reliability results

The laser module customer/system supplier (SS) shall have a programme to analyse and

verify a laser manufacturer’s reliability claims. In particular:

– life test data for the complete laser module;

– life test data for initial components, for example laser diode and photodiode;

– environmental test result, i.e. inspection requirements group B, C of the detail

specification;
– where appropriate, see Clause 5, the data and test results of appropriate CQCs.
The analysis of results should lead to reporting of the laser module reliability parameters for
each of the laser module types. Minimum reliability parameters are presented as in Table 3.
Where data reveals more than one wear-out mechanism, median life and dispersion in each
case shall be stated.
The failure criteria used to derive these reliability parameters shall be agreed between the
laser customer/system suppliers (SS) and laser module manufacturer (LMM). The criteria will
be stated in the detail specification, see IEC/ TR 61752-2
Table 3 – Performance for laser module reliability parameters
Parameter Measured value
Median life (ML) at 25 °C: Years
see NOTE 3
Dispersion(s)
Wear-out failure rate
at 5 years (λ) FITs
FITs
at 10 years (λ)
FITs
at 20 years (λ)
Wear-out activation energy eV
Random failure rate
(λ FITs
a) @ 25 °C: see NOTE 3
%
Confidence limits used:
Random failure activation energy eV
NOTE 1 This table assumes a log-normal distribution of times to failure. The dispersion parameter is the
standard deviation of the logarithm to the base ‘e’ of the times to failure. See IEC/TR 62752-2:2.
NOTE 2 The reference temperature used for all parameters in this table is 25 °C. An alternative reference
temperature (50 °C) may be used provided activation energies are given.
NOTE 3 Special attention should be paid to all extrapolation models used and the justification for activation
energies employed in reliability predictions is to be stated
Guidance on these activities is given in IEC/TR 62752-2.

6.2 Technical visits to LMMs
Laser module designs continue to evolve and a LMM may introduce significant changes which
impinge on reliability. Under the negotiation between customer and manufacturer, technical
visits should be performed until there is sufficient evidence of a maturing technology and

– 14 – 62572-3 © IEC:2011
production stability. These technical meetings/visits shall contain an item on the agenda that

concerns quality and reliability. Where a LMM holds a capability approval, the frequency of

these technical visits may be reduced provided the manufacturer can demonstrate:

a) that the CQCs fully represent any relevant design, process updates and reliability issues;

b) satisfactory self-audit of the quality system.

6.3 Design/process changes
The customer/system supplier (SS) shall be informed by the laser module manufacturer (LMM)

of any design or process change which may affect the form, fit or function of the end product.

6.4 Deliveries
Laser module designs will continue to evolve and therefore each delivered lot shall be
manufactured according to a stated technology and production process.
This should be verified by the supplier/ and customer before delivery.
6.5 Supplier documentation
The laser customer/system supplier (SS) and component manufacturer or LMM shall
incorporate, wherever possible, the tests and activities described in this standard into their in-
house component qualification, or where appropriate, capability approval procedures and
purchasing specifications. This documentation will be used in reliability/technical
presentations, tender submission, marketing briefs to customers.

62572-3 © IEC:2011 – 15 –
Annex A
(informative)
Guidance on testing in Table 1 and Table 2

A.1 Laser module life tests containing thermoelectric coolers (for example,

Peltier, Test 1.1, Table 1)
With laser modules containing thermoelectric coolers it is difficult to provide a significant

degree of overstress to all key components simultaneously. During “normal operation”, the
laser submount temperature is usually controlled at T = 25 °C. However, for a life test with a
s
case temperature of T = T , a useful stress can be obtained for the laser diode, fibre
c op max
fixing, photodiode and thermal sensor if the cooler is operated at a relatively high current to
maintain a submount temperature of T = T . The conditions in Table A.1 are
s s nom
recommended.
Some additional testing of the cooler is recommended, for example T = T and T = T – 10 °C.
c op max s s
Table A.1 – Recommended life test conditions for laser modules
containing Peltier coolers
Case temperature T
op max
Laser submount temperature T = T
s s nom
Fibre output set to P at start of life test
Optical power
max
(using monitor circuit)
Laser current To maintain constant monitor output
Monitor current Normal bias
Thermal sensor current Normal bias
Cooler current To maintain constant thermistor resistance
(or sensor conditions)
Duration
> 5 000 h
A.2 Laser module life tests – Uncooled module (Test 1.2, Table 1)
For modules without thermoelectric coolers (for example Peltier), life tests can be readily

performed over a range of temperatures up to the recommended maximum operating
temperature for the module. During initial qualification, service life tests at two or more
temperatures, for example T = T and T 40 °C to 50 °C, are recommended. Here, the
c op max c
accuracy of lifetime estimation becomes high in proportion to the number of test levels.
An additional life test at low temperature (duration > 2 000 h at T ) may be required for
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modules containing epoxies or organic materials.
If only a single life test is to be performed, for example during maintenance of qualification
testing, the conditions in Table A.2 are recommended:

– 16 – 62572-3 © IEC:2011
Table A.2 – Recommended life test conditions for uncooled laser modules

Case temperature T
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Optical power Fibre output set to P at start of life test
max
(using monitor circuit)
Laser current To maintain constant monitor photocurrent

Monitor photocurrent Normal bias

Duration
> 5 000 h
A.3 Laser diode life tests on submounts (Test 1.3, Table 1)
The laser life test shall be performed with the laser operating at constant light output, as it
would be in normal operation, unless otherwise agreed with the ONS. Temperatures in the
range T = 50 °C to 80 °C are often used. The acceleration in the rate of degradation, relative
s
to normal operation, is therefore relatively small. The maximum temperature at which life tests
can be performed under lasing operating conditions is usually in the range T = 70 °C to
s
100 °C. However, constant current/life tests at temperatures up to T = 150 °C can be useful
s
in studying the reliability of contact metallizations. Actual failures do not often occur in well
screened laser diodes tested at temperatures T < 90 °C. In order to estimate the laser life
s
some extrapolation is required to predict when the threshold or operating current will exceed
the pre-determined failure criterion. To obtain a reasonable increase in operating current, a
life test duration greater than 5 000 h is required.
If a single life test is to be performed, for example during maintenance of qualification testing,
the conditions in Table A.3 are recommended:
Table A.3 – Recommended laser diode life test conditions
Temperature T = 70 °C
s
Optical power Maximum specified
Bias To maintain constant monitor output
Duration
> 5 000 h
A.4 Monitor photodiode life tests (Test 1.4, Table 1)

Photodiode life tests are best performed with the devices under reverse bias if the
susceptibility to increased dark current is to be assessed. To obtain failures in a reasonable
timescale, temperatures in the range T = 125 °C to 200 °C are usually required. Devices with
s
organic passivations should be tested at temperatures below the curing temperature of the
passivation.
Increased bias voltage can also be used to accelerate failure, but the dependence of lifetime
on voltage would then need to be determined before a prediction of operating lifetime could
be made.
It is necessary for measurements of photodiode dark currents to include measurement at the
normal operating temperature. Measurements made at only the life test temperature may not
detect increased surface leakage, because bulk dark currents dominate at high temperatures.
Failed photodiodes with increased dark currents (as a result of the accumulation of mobile
charge) will often recover quickly if stored at high temperatures without bias. It is essential,
that at the end of the test duration, the reverse bias conditions shall be maintained until the

62572-3 © IEC:2011 – 17 –
temperature is below 30 °C. The post test measurements shall be completed within 3 h. The

increase in dark current of photodiodes with exposed junctions (for example unpassivated

mesa devices) is very sensitive to the package atmosphere, and small traces of oxygen or

water vapour can result in decreased lifetimes. Life tests should therefore be performed with

the photodiodes sealed in representative hermetic packages, and not on open submounts.

Tests in flowing (nominally dry) nitrogen can produce variable results. The conditions in Table

A.4 are recommended.
Table A.4 – Recommended photodiode life test conditions

Temperature In the range T = 125 °C to 200 °C
s
Bias Specified maximum reverse bias voltage.
Bias to be maintained during cool down prior to
measurements
Duration 1 000 h
Atmosphere Photodiode in representative hermetic package

A.5 Temperature cycling and thermal shock (Test 3, Table 1 and Test 2,
Table 2)
It is difficult to quantify the acceleration (with respect to normal operation) obtained from a
temperature cycling test. Nevertheless, it has been clearly demonstrated that temperature
cycling from T = –40 °C to +70 °C can reveal potentially serious hazards in laser modules
c
associated with fibre instability, thermal mismatch between piece parts (for example coolers
and submounts), and with fibre breaks.
For initial qualification, number of cycles = 500 from T to T are required. For
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periodic testing (3 and/or 6 monthly), number of cycles = 100. The temperature cycling
procedure should follow either:
a) IEC 60068-2-14, Test Na: two-chamber method;
b) IEC 60068-2-14, Test Nb: single-chamber method, rate of change equal to 1, 3, or 5 °C/min.
Well designed and constructed modules should be able to withstand such a test with
negligible changes in module performance.
A.6 Sealing/hermeticity (Test 4, Table 1 and Test 3, Table 2)

The post-test assessment for Test 4, Table 1 and Test 3, Table2 shall be fine-leak testing,
Test Qk, followed by the gross-leak Test Qa. Suitable precautions shall be taken to eliminate
absorption of helium by the fibre coating to avoid measurement errors.
A.7 Shock and vibration (Test 5, Table 1 and Test 4, Table 2)
These tests are designed to simulate conditions involving vibration and shock that a
component may be subjected to in service or during transportation. For a module with
thermoelectric cooler the cooler is the limiting device, so the shock test should be limited to
500 G.
A.8 High-temperature storage (Test 6, Table 1 and Test 5, Table 2)
Temperature storage testing has the advantage of being relatively inexpensive because no
bias circuitry is required. Provided the test is performed at or below the maximum storage

– 18 – 62572-3 © IEC:2011
≤ T , it can be regarded as non-destructive. Storage at
temperature for the module T
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high temperatures (for example T = 70 °C, duration = 1 000 h) will, although the stress is
c
relatively small, provide useful protection against major problems with fibre alignment

instability and will identify some potential metallization and solder failure mechanisms, for

example thermoelectric cooler or thermistor failures.

A.9 Electrostatic discharge sensitivity (ESD) (Test 7, Table 1 and Test 6,

Table 2)
Optoelectronic components are sensitive to damage by electrostatic discharge (ESD) at all

stages during manufacture, testing, assembly into equipment and operation. Exposure to ESD

can result in sudden failure, parametric shifts, or even latent damage leading to a reduced
lifetime during subsequent operation. The sensitivity of the laser and monitor photodiode to
ESD damage should be determined so that the appropriate level of precautions can be taken
to avoid damage.
The minimum recommended testing for modules is to subject six laser diodes and six monitor
photodiodes on a wafer basis, to the “human body model” test described in MIL-STD-883,
method 3015. However, rather than applying a single go-no-go test condition, transients of
increasing voltage should be applied to determine the threshold at which failures occur.
Failure should be defined as a parametric change in:
– photodiode dark current or in laser threshold current;
– slope efficiency;
– forward voltage;
– reverse leakage current or light output spectrum.
The criteria are given in IEC/TR 62752-2:2008, Table 3.
A.10 Residual gas analysis (RGA) (Test 8, Table 1 and Test 7, Table 2)
Certain laser module reliability hazards associated with high package water content are
unlikely to be detected with the testing described in Tables 1 and 2. Hermeticity testing and
residual gas analysis of transmitter modules is necessary to demonstrate that the module
package contains a dry, inert atmosphere throughout its operating life. High-temperature life
testing alone is not likely to detect reliability hazards associated with high package water
content. See also A.2 and Tables 1 and 2, Test 7.

Caution: the pre-bake temperature for RGA in MIL-STD-883, method 1018 is 120 °C. This
may be greater than the storage temperature T of most optoelectronic components. A
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lower pre-bake temperature of T = T for a longer period is therefore recommended until
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the background level of RGA remains constant. This level can then be eliminated from the
results.
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