IEC 60749-34:2010

IEC 60749-34 ®
Edition 2.0 2010-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Semiconductor devices – Mechanical and climatic test methods –
Part 34: Power cycling
Dispositifs à semiconducteurs – Méthodes d’essais mécaniques et climatiques –
Partie 34: Cycles en puissance

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IEC 60749-34 ®
Edition 2.0 2010-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Semiconductor devices – Mechanical and climatic test methods –
Part 34: Power cycling
Dispositifs à semiconducteurs – Méthodes d’essais mécaniques et climatiques –
Partie 34: Cycles en puissance

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
L
CODE PRIX
ICS 31.080.01 ISBN 978-2-88912-232-5
– 2 – 60749-34 © IEC:2010
CONTENTS
FOREWORD.3
1 Scope and object.5
2 Normative references .5
3 Terms and definitions .5
4 Test apparatus .6
5 Procedure .7
6 Test conditions .7
7 Precautions .8
8 Measurements.9
9 Failure criteria .9
10 Summary.9
Bibliography.10

Figure 1 – Typical load power P and temperature cycle test condition 2.8

Table 1 – Test conditions.8

60749-34 © IEC:2010 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SEMICONDUCTOR DEVICES –
MECHANICAL AND CLIMATIC TEST METHODS –

Part 34: Power cycling
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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
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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 60749-34 has been prepared by IEC technical committee 47:
Semiconductor devices.
This second edition cancels and replaces the first edition published in 2004 and constitutes a
technical revision. The significant changes with respect from the previous edition include:
– the specification of tighter conditions for more accelerated power cycling in the wire bond
fatigue mode;
– information that under harsh power cycling conditions high current densities in a thin die
metalization might initiate electromigration effects close to wire bonds.

– 4 – 60749-34 © IEC:2010
The text of this standard is based on the following documents:
FDIS Report on voting
47/2068/FDIS 47/2079/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.
A list of all parts in the IEC 60749 series, under the general title Semiconductor devices –
Mechanical and climatic test methods, can be found on the IEC website.
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.
60749-34 © IEC:2010 – 5 –
SEMICONDUCTOR DEVICES –
MECHANICAL AND CLIMATIC TEST METHODS –

Part 34: Power cycling
1 Scope and object
This part of IEC 60749 describes a test method used to determine the resistance of a
semiconductor device to thermal and mechanical stresses due to cycling the power
dissipation of the internal semiconductor die and internal connectors. This happens when low-
voltage operating biases for forward conduction (load currents) are periodically applied and
removed, causing rapid changes of temperature. The power cycling test is intended to
simulate typical applications in power electronics and is complementary to high temperature
operating life (see IEC 60749-23). Exposure to this test may not induce the same failure
mechanisms as exposure to air-to-air temperature cycling, or to rapid change of temperature
using the two-fluid-baths method. This test causes wear-out and is considered destructive.
NOTE It is not the intention of this specification to provide prediction models for lifetime evaluation.
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 60747-1:2006, Semiconductor devices – Part 1: General
IEC 60747-2:2000, Semiconductor devices – Discrete devices and integrated circuits – Part 2.
Rectifier diodes
IEC 60747-6:2000, Semiconductor devices – Part 6: Thyristors
IEC 60749-3, Semiconductor devices – Mechanical and climatic test methods – Part 3:
External visual examination
IEC 60749-23, Semiconductor devices – Mechanical and climatic test methods – Part 23: High
temperature operating life
3 Terms and definitions
For the purposes of this document the following terms and definitions apply.
NOTE Further terms and definitions concerning semi-conductor devices are contained in the IEC 60747 and
IEC 60748 series.
3.1
load current
current to which the devices are subjected to produce power loss P
3.2
case temperature
T
c
temperature of the base of the device under test facing the heat sink

– 6 – 60749-34 © IEC:2010
3.3
sink temperature
T
s
temperature of the heat sink measured in close proximity to the device under test
3.4
junction temperature excursion
ΔT
vj
difference between maximum and minimum virtual junction temperature of the device under
test during one power cycle
3.5
case temperature excursion
ΔT
c
difference between maximum and minimum case temperature during one power cycle
3.6
on-time
time interval while device under test is conducting load current
3.7
power loss
P
power dissipation of the devices under test as calculated from current waveform during on-
time and from characteristic data in the procurement documents
3.8
off-time
time interval for cooling down
3.9
cycle period
sum of on-time and off-time
4 Test apparatus
The apparatus required for this test shall consist of heat sinking for a group of devices or
alternatively for each individual device under test with the purpose of dissipating the forward
conduction losses and of controlling on- and off-times. The heat sinking can be selected from
natural or forced air convection or liquid cooling. Pre-selected temperature excursions of the
device ground plates and of the die junctions, as well as on- and off-times determine heat
sinking set-up and parameters.
Sockets or other mounting means shall be provided so that reliable electrical contact can be
made without excessive heat transfer to the device terminals. Power supplies shall be
capable of maintaining the specified operating conditions throughout the testing period
despite normal variations in line voltage or ambient temperatures. On- and off-switching of
load currents should be provided by the test circuit independent of any (gate-) control
functions of the devices under test. On- and off-times (cycle period) shall be controlled by
monitoring either heat sink T or case temperature T . Alternatively, the cycle period can also
s c
be controlled by fixed time settings, if appropriate.
The test circuit should also be designed so that the existence of abnormal or failed devices
does not alter the specified conditions for other units on test (e.g. the latter might be
accomplished by exchanging defective units with new ones). Care should be taken to avoid
possible damage from transient voltage spikes or other conditions that might result in
electrical, thermal or mechanical overstress.

60749-34 © IEC:2010 – 7 –
5 Procedure
When special mounting or heat sinking is required, the details shall be specified in the
applicable procurement documents. Load current and waveforms shall be selected close to
the preferred application of the devices under test, as outlined below.
Rectifier devices such as diodes or SCRs that are normally used as a.c. lines converters
should be connected to 50 Hz or 60 Hz a.c. power supplies; bridge rectifiers should be
operated as such, i.e. a.c. line voltages applied to the a.c. input terminals and output
terminals shorted via shunt resistors to monitor load current.
MOS-controlled devices such as power MOSFETs or IGBTs should be connected to d.c.
power supplies.
Modules with multiple functions can be operated stepwise and separate according to their
internal circuits.
Gate-controllable devices such as SCRs, IGBTs and MOSFETs should be set into a
continuous forward conductive state by appropriate gate controls throughout the entire test
duration.
The power should be applied and suitable checks made to assure that all devices are properly
biased. During the test, the power applied to the devices shall be alternately cycled as given
in Table 1, unless otherwise specified in the relevant specification. The devices shall
concurrently be cycled between temperature extremes for the specified number of cycles.
The power cycling test shall be continuous except when parts are removed from the test
fixtures for interim electrical measurements. If the test is interrupted as a result of device,
power or equipment failure, the test shall restart from the point of stoppage.
6 Test conditions
The test condition shall be selected from those outlined in Table 1. The relationship of on-time
to off-time shall be the same for all devices under test. It is sufficient that T or T is
s c
monitored closely below the centre of one device under test, provided that load and heat
sinking conditions are properly controlled for all other devices.
Junction temperatures T , junction temperature excursions ΔT and case temperature
vj vj
excursions ΔT , shall be kept within the same range for all devices, as given in Table 1 below.
c
+5
Off-time shall be adjusted until T has approached T within °C before a new cycle starts,
vj c
as illustrated in Figure 1.
(and case temperatures T if applicable) shall be calculated from
Junction temperatures T
vj c
the given thermal impedances in the applicable procurement documents and from the power
loss P of the devices under test, taking into account load current waveforms.
The number of cycles N to be performed shall be selected in integer multiples of
c
– 100 000 for test condition 1,
– 1 000 for test conditions 2 and 3.
No minimum requirements for N are defined since this figure is very dependent on the
c
application; N might be millions of cycles in traction applications under test condition 1.
c
– 8 – 60749-34 © IEC:2010
Table 1 – Test conditions
Temperature extremes
Test Cycle ΔT Example of
vj
ΔT T
condition period °C failure mode

c vj
°C °C
45 (±5) to
1a
0 60 ± 5
125 ( )
−10
Sensitive to wire
a
1 s to 15 s
< 30
b
bond fatigue
45 (±5) to
1b 0 80 ± 5
150 ( )
−10
45 (±5) to
2 75 ± 5
50 (±20) 0
125 ( )
−10
Sensitive to soft
1 min to
c
solder and
15 min
45 (±5) to
wire bond fatigue
3 60 (±20) 0 95 ± 5
150 ( )
−10
a
ΔT might be very small because the device is normally operated in transient regime during short cycling.

c
b
See [1] . Under harsh power cycling conditions high current densities in a thin die metalization might initiate
electromigration effects close to wire bonds.
c
See [2].
T
vj
T  °C
T
c
P
P
Time
IEC  135/04
Figure 1 – Typical load power P and temperature cycle test condition 2
7 Precautions
Load currents and total power loss shall not exceed specified maximum values per device.
The circuit should be structured so that the maximum rated case or junction temperatures
shall not be exceeded. Precautions should be taken to avoid electrical damage and thermal
runaway. The test set-up should be monitored initially and at the conclusion of a test interval
to establish that all devices are being stressed to the specified requirements. Deviations shall
be corrected after initial monitoring to assure the validity of the qualification data.
___________
1)
Figures in square brackets refer to the Bibliography.

60749-34 © IEC:2010 – 9 –
8 Measurements
The electrical measurements and visual inspections shall be made at intervals in accordance
with the relevant specification.
9 Failure criteria
After exposure to the test, or during the course of the test, a device shall be defined as a failure,
if failure-defining characteristics exceed the limits given in 7.2 of IEC 60747-1:2006, with further
reference to Table 2 of IEC 60747-2:2000 and Table 3 of IEC 60747-6:2000. Mechanical
damage, such as cracking, chipping or breaking of the package (as defined in IEC 60749-3)
shall be considered a failure, provided that fixing or handling did not induce such damage.
10 Summary
The following details shall be specified in the relevant specification:
a) special mounting if applicable (see Clause 5);
b) test conditions from Table 1;
c) load current and shape of current (see Clause 7);
d) switch-on time, switch-off time or cycle time
...