IEC 62435-4:2018

IEC 62435-4 ®
Edition 1.0 2018-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electronic components – Long-term storage of electronic semiconductor
devices –
Part 4: Storage
Composants électroniques — Stockage de longue durée des dispositifs
électroniques à semiconducteurs
Partie 4: Stockage
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IEC 62435-4 ®
Edition 1.0 2018-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electronic components – Long-term storage of electronic semiconductor

devices –
Part 4: Storage
Composants électroniques — Stockage de longue durée des dispositifs

électroniques à semiconducteurs

Partie 4: Stockage
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.020 ISBN 978-2-8322-6237-5

– 2 – IEC 62435-4:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Purpose of storage (facility) . 10
4.1 General . 10
4.2 Cost of ownership . 10
4.3 Security . 10
4.4 Location and ambient environment . 10
4.5 Incorrect control of reliability during storage . 10
5 Storage . 10
5.1 General . 10
5.2 Type of environment . 11
5.3 Storage identification – traceability . 11
5.4 Initial packaging . 11
5.5 Storage conditions . 12
5.5.1 General . 12
5.5.2 Storage area . 12
5.6 Maintaining storage conditions . 13
6 Periodic check of the components . 13
6.1 Objectives . 13
6.2 Periodicity . 13
6.3 Tests during periodic check . 14
7 Removal from storage . 14
7.1 Precautions . 14
7.2 Electrostatic discharges . 14
8 Materials used in storage regimes . 14
8.1 General . 14
8.2 Moisture barrier bags (MBB) . 14
8.3 Desiccant . 15
8.4 Humidity indicator card (HIC) . 15
8.5 Dry nitrogen atmosphere . 15
8.6 High purity dry air atmosphere . 15
8.7 Storage containers . 16
8.8 Foams, packing material and protective cushioning . 16
9 General storage environment . 16
10 LTS methods . 16
10.1 General . 16
10.2 Dry cabinet storage . 17
10.2.1 General . 17
10.2.2 Humidity controlled storage . 17
10.2.3 Oxygen (O )-controlled storage . 17
10.2.4 Outgassing-controlled storage . 17
10.3 MBB storage . 17
10.3.1 General . 17

10.3.2 Humidity-controlled storage . 17
10.3.3 Oxygen (O )-voided storage . 17
10.3.4 Outgassing controlled storage . 18
10.3.5 Nitrogen (N ) positive-pressure MBB storage . 18
11 LTS double containment redundancy . 18
Annex A (normative) Example checklist for long-term storage facilities . 19
Bibliography . 20

Table A.1 – Example checklist for storage facilities . 19

– 4 – IEC 62435-4:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC COMPONENTS – LONG-TERM STORAGE
OF ELECTRONIC SEMICONDUCTOR DEVICES –

Part 4: Storage
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,
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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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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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 62435-4 has been prepared by IEC technical committee 47:
Semiconductor devices.
This bilingual version (2018-11) corresponds to the monolingual English version, published in
2018-06.
The text of this International Standard is based on the following documents:
FDIS Report on voting
47/2469/FDIS 47/2486/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.

The French version of this standard has not been voted upon.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62435 series, published under the general title Electronic
components – Long-term storage of electronic semiconductor devices, can be found on the
IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 62435-4:2018 © IEC 2018
INTRODUCTION
This standard applies to the long-term storage of electronic components.
This is a standard for long-term storage (LTS) of electronic devices drawing on the best long-
term storage practices currently known. For the purposes of this document, LTS is defined as
any device storage whose duration may be more than 12 months for products scheduled for
long duration storage. While intended to address the storage of unpackaged semiconductors
and packaged electronic devices, nothing in this document precludes the storage of other
items under the storage levels defined herein.
Although it has always existed to some extent, obsolescence of electronic components and
particularly of integrated circuits, has become increasingly intense over the last few years.
Indeed, with the existing technological boom, the commercial life of a component has become
very short compared with the life of industrial equipment such as that encountered in the
aeronautical field, the railway industry or the energy sector.
The many solutions enabling obsolescence to be resolved are now identified. However,
selection of one of these solutions should be preceded by a case-by-case technical and
economic feasibility study, depending on whether storage is envisaged for field service or
production, for example:
• remedial storage as soon as components are no longer marketed;
• preventative storage anticipating declaration of obsolescence.
Taking into account the expected life of some installations, sometimes covering several
decades, the qualification times and the unavailability costs, which can also be very high, the
solution to be adopted to resolve obsolescence should often be rapidly implemented. This is
why the solution retained in most cases consists in systematically storing components which
are in the process of becoming obsolescent.
The technical risks of this solution are, a priori, fairly low. However, it requires perfect mastery
of the implemented process and especially of the storage environment, although this mastery
becomes critical when it comes to long-term storage.
All handling, protection, storage and test operations are recommended to be performed
according to the state of the art.
The application of the approach proposed in this document in no way guarantees that the
stored components are in perfect operating condition at the end of this storage. It only
comprises a means of minimizing potential and probable degradation factors.
Some electronic device users have the need to store electronic devices for long periods of
time. Lifetime buys are commonly made to support production runs of assemblies that well
exceed the production timeframe of their individual parts. This puts the user in a situation
requiring careful and adequate storage of such parts to maintain the as-received solderability
and to minimize any degradation effects to the part over time. Major degradation concerns are
moisture, electrostatic fields, ultra-violet light, large variations in temperature, air-borne
contaminants and outgassing.
Warranties and sparing also present a challenge for the user or repair agency, as some
systems have been designated to be used for long periods of time, in some cases for up to
40 years or more. Some of the devices needed for repair of these systems will not be
available from the original supplier for the lifetime of the system, or the spare assembly can
be built with the original production run but then require long-term storage. This document
was developed to provide a standard for storing electronic devices for long periods of time.

The storage of devices that are moisture sensitive but that do not need to be stored for long
periods of time is dealt with in IEC TR 62258-3.
Long-term storage assumes that the device is going to be placed in uninterrupted storage for
a number of years. It is essential that it be useable after storage. It is important that storage
media and the local environment are considered together.
These guidelines do not imply any warranty of product or guarantee of operation beyond the
storage time given by the manufacturer.
The IEC 62435 series is intended to ensure that adequate reliability is achieved for devices in
user applications after long-term storage. Users are encouraged to request data from
suppliers to applicable specifications to demonstrate a successful storage life as requested by
the user. These standards are not intended to address built-in failure mechanisms that would
take place regardless of storage conditions.
These standards are intended to give practical guidance on methods of long-duration storage
of electronic components, where this is intentional or involves planned storage of a product
for a number of years. Storage regimes for work-in-progress production are managed
according to company internal process requirements and are not detailed in this series of
standards.
The overall standard series is split into a number of parts. Parts 1 to 4 apply to any long-term
storage and contain general requirements and guidance, whereas Parts 5 to 9 are specific to
the type of product being stored.
Electronic components requiring different storage conditions are covered separately starting
with Part 5.
The structure of the IEC 62435 series as currently planned consists of the following:
Part 1 – General
Part 2 – Deterioration mechanisms
Part 3 – Data
Part 4 – Storage
Part 5 – Die and wafer devices
Part 6 – Packaged or finished devices
Part 7 – MEMS
Part 8 – Passive electronic devices
Part 9 – Special cases
– 8 – IEC 62435-4:2018 © IEC 2018
ELECTRONIC COMPONENTS – LONG-TERM STORAGE
OF ELECTRONIC SEMICONDUCTOR DEVICES –

Part 4: Storage
1 Scope
This part of IEC 62435 specifies long-term storage methods and recommended conditions for
long-term storage of electronic components including logistics, controls and security related to
the storage facility. Long-term storage refers to a duration that may be more than 12 months
for products scheduled for long duration storage. The philosophy of such storage, good
working practices and general means to facilitate the successful long-term storage of
electronic components are also addressed.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60749-20-1, Semiconductor devices – Mechanical and climatic test methods – Part 20-1:
Handling, packing, labelling and shipping of surface-mount devices sensitive to the combined
effect of moisture and soldering heat
IEC TR 62258-3, Semiconductor die products – Part 3: Recommendations for good practice in
handling, packing and storage
IEC 61340-5-2, Electrostatics – Part 5-2: Protection of electronic devices from electrostatic
phenomena – User guide
JEDEC J-STD-033, Standard for handling, packing, shipping, and use of moisture/reflow
sensitive surface mount devices
MIL-PRF-27401, Propellant pressurizing agent nitrogen
MIL-PRF-81705, ESD Materials, Bags and Performance Specification
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
storage environment
specially controlled storage area, with particular control of temperature, humidity, atmosphere
and any other conditions depending on the product requirements

3.2
moisture sensitivity level
MSL
rated and verified moisture sensitivity level assigned to a component that defines the
maximum safe equilibrium moisture exposure for a specific encapsulated device prior to
reflow assembly or rework
3.3
long-term storage
LTS
planned storage of components to extend the life-cycle for a duration with the intention of
supporting future use
3.4
LTS storeroom
area containing components that have additional packaging for storage to protect from
moisture or from mechanical impact or for ease of identification or handling
3.5
moisture-sensitive device
MSD
device that has moisture absorption or moisture retention and whose quality or reliability is
affected by moisture
3.6
electronic device
packaged electrical, electronic, electro-mechanical (EEE) item, or assemblies using such
items
[SOURCE: IEC 60050-551:1998, 551-14-01, modified]
3.7
desiccant
hygroscopic substance used to remove moisture from an atmosphere
3.8
moisture barrier bag
MBB
storage bag manufactured with a flexible laminated vapour barrier film that restricts the
transmission of water vapour
Note 1 to entry: Refer to IEC 60749-20-1 for packaging of moisture sensitive products.
3.9
humidity indicator card
HIC
card printed with a moisture sensitive chemical that changes from blue to pink in the presence
of water vapour
3.10
water vapour transmission rate
WVTR
measure of permeability of MBBs to water vapour
3.11
electrostatic discharge
ESD
transfer of electric charge between bodies of different electrostatic potentials in proximity or
through direct contact
[SOURCE: IEC 60050-561:2014, 561-03-06]

– 10 – IEC 62435-4:2018 © IEC 2018
4 Purpose of storage (facility)
4.1 General
Successful long-term storage is dependent upon sustained control of the environment and its
physical and data security. Costs associated with handling, maintaining traceability, physical
accounting and environmental conditions should be accounted for from the outset of long-term
storage.
4.2 Cost of ownership
Cost will be determined by type of storage facility, cabinet, continuous nitrogen flow or inert
gas flow and periodical examination on a representative sample.
4.3 Security
Access to controlled areas should be limited to a small number of persons to ensure adequate
security. Controlled areas shall be secure from theft, tampering and environmental
disturbances.
4.4 Location and ambient environment
The LTS storeroom should be located away from any vibration, electromagnetic fields,
ultraviolet rays and other strong light. Consideration should be given to any catastrophic
events likely to occur near or at the physical locale of the storage facility. For example,
seismically active locations may have building safety and control mitigation measures in place.
4.5 Incorrect control of reliability during storage
Storage conditions should be precisely defined and controlled, to ensure the reliability of the
components (see Clause 5).
Component integrity may be reduced by improper storage conditions. Potential causes of
storage risk are related to poor control of environmental conditions. Proper control should
consider temperature, humidity, moisture, pressure, atmospheric gases, electrostatic field
charge, applied physical forces, handling (shock, vibration, impacts, etc.), contamination or
other applied stress factors. Degradation mechanisms that are induced with moisture may
occur if the integrity of the dry storage (cabinet or MBB) is violated. Verification of moisture
exposure includes, but is not limited to, examination of the HIC for any change in colour,
chamber humidity monitoring and the use of recording devices that indicate moisture
exposure. Different materials can absorb moisture at different rates and should be evaluated
based upon exposure time. For other degradation mechanisms that require oxygen, radiation,
electrical exposure or mechanical impact, the LTS environment should be evaluated to
prevent contributing to failure concerns.
Packing materials used in LTS should be evaluated for moisture absorption and release. The
packing requirements of IEC 60749-20-1 or J-STD-033 should be followed for LTS unless
otherwise indicated in this publication.
5 Storage
5.1 General
The following 5.2 to 5.6 describe storage environments and practices within the storage
facility.
5.2 Type of environment
Various types of storage environments exist, such as:
– air without any monitoring;
– “dry”-air (relative humidity lower than 7 % – 25 %), with or without active desiccant, which
may be in a sealed moisture barrier bag;
– low-oxygen; typically nitrogen (racks, bags, tubes, etc.) where a nitrogen or oxygen
detector is recommended;
– vacuum in fully evacuated chamber (with precautions to prevent part-crushing damage or
bag foil damage if used).
The selection of a solution shall be made on the basis of the intended storage time, the
application of the technology and the accepted risks. For long-term storage, a dry-air, nitrogen
or vacuum solution is recommended.
5.3 Storage identification – traceability
Storage of part manufacturing data, unit level traceability and various other data that is
recorded during storage should be maintained and archived. Data storage practices and
. Data to be stored coincident with
requirements are planned to be addressed in IEC 62435-3
the environment should include:
– the component manufacturer's name and part number;
– the procurement source;
– the date-code;
– the storage history;
– the validation test identification or program version performed.
The purpose of this data is to accurately identify the components stored, to ensure the
traceability and enable tracking of components.
When there are periodic checks, the following data should be recorded and compared to the
previous checks: date, nature of the checks, components tested, results.
5.4 Initial packaging
Initial packaging may not be suitable for long-term storage, and consideration should be made
as to the method of packing for storage, in particular, re-packing devices in special protective
material that will not degrade or out-gas during storage. ESD controls and protection
guidelines are found in IEC TR 61340-5-2 and recommendations for ESD protective materials
are found in IEC 61340-5-3.
If packaging fails, the components should be assessed for further handling and additional
storage, and if necessary the components should be repackaged. This type of operation can
only be performed in exceptional circumstances during storage because the components
could be degraded or damaged.
Re-package all devices in accordance with the specified storage environment. Parts should
be exposed to ambient air for as limited a time as possible. If re-packing is required it should
be completed within 8 h or less. Care should be taken to avoid part contamination through
foreign material by segregating component bag opening and storage preparation areas.
Containers may be reused, as long as they are visibly inspected and show no damage. Where
desiccant is required, fresh or refreshed desiccant should be used for initial storage and for
every subsequent re-packaging.
_____________
Under preparation. Stage at the time of publication: IEC/PCC 62435-3:2018.

– 12 – IEC 62435-4:2018 © IEC 2018
5.5 Storage conditions
5.5.1 General
To ensure the integrity of the components during LTS, the conditions of the storage
environment should be maintained.
5.5.2 Storage area
5.5.2.1 General
The stock shall be stored in clean premises or LTS storeroom, in compliance with the
requirements of 5.5.2.2 to 5.5.2.9.
5.5.2.2 Temperature
Many aging mechanisms are accelerated by temperature. The temperature should be
maintained between 5 °C and 40 °C condition, environment description 1K21, as prescribed
by IEC 61760-2, IEC 60721-3-1 and JEDEC JEP-160.
5.5.2.3 Temperature variations
Generally, temperature variations provoke the premature aging of assemblies made of
different materials. The temperature ranges given in 5.5.2.2 describe only the minimum and
maximum possible over a given year and not the daily temperature or seasonal temperature
variation.
5.5.2.4 Relative humidity – chemical attacks – contamination
In addition to “popcorning” of MSDs during surface mount, humidity, as well as any form of
chemical attack or contamination, creates a corrosion hazard for electronic components.
By reducing all contamination sources and by maintaining a relative humidity lower than 50 %,
these risks are significantly reduced. It is worth pointing out, however, that a relative humidity
lower than 20 % will favour the development of electrostatic discharges.
Dry nitrogen storage practically eliminates all corrosion and contamination problems.
5.5.2.5 Pressure
The possible pressure variation between the storage environment and the outside atmosphere
should be taken into account.
5.5.2.6 Electrostatic discharges
Electrostatic discharges (ESDs) are an important cause of failure in electronic components.
Specific measures to reduce failures to a minimum shall be taken (see IEC 61340-5-2), for
instance:
– component storage in anti-static protections (bags, strips, conductive foams);
– metallic racks connected to earth;
– component storage in antistatic containers;
– protection of the work stations (straps, working surfaces, dissipaters, etc.);
– raising awareness of ESD problems to the operators and managers responsible for
storage of the components; maintenance of relative humidity at greater than 7 % to avoid
charge build-up and discharge;
– use of air ionizers.
Antistatic protection equipment (bags, strips) generally have a limited useable life-time, either
because of surface treatment abrasion phenomena or under the impact of ultraviolet rays.
5.5.2.7 Vibration – mechanical impacts
Stored components should be kept away from any constant vibration source. The
maintenance and destocking operations concerning components and other elements should
be performed in such a way as to keep to a minimum the risks of mechanical damage to the
stock.
Effectiveness of antistatic protection of strips should be maximized by careful surface
treatment (except for carbon-charged strips). This treatment can be highly damaged by
abrasion due to friction of the component leads in the strip. Components should, therefore, be
blocked in the strips. Stored component handling should be kept to a minimum, in order to
avoid the premature aging of the strips.
5.5.2.8 Electromagnetic field – radiations
Stored components should be kept away from any high intensity or constant exposure to
greater than supplier-specified radiation and electromagnetic fields.
5.5.2.9 Light
Light, especially ultraviolet rays, can lead to a degradation of organic materials (packing bags,
antistatic strips, etc.). The components should be stored away from light.
5.6 Maintaining storage conditions
The role of the equipment is to ensure that storage conditions are maintained within the limits
defined to ensure the best integrity of the component properties. Equipment should be
regularly checked and adjusted or repaired if required: heating, air conditioning, temperature
and relative humidity measurement systems, ionizers, protections against ESDs
(see IEC 61340-5-1), etc.
Checking and maintenance operations are recorded.
6 Periodic check of the components
6.1 Objectives
The most important stresses electronic components may suffer during storage are of the
mechanical, thermal and chemical types. These stresses may be internal or external to the
component.
The risks to quality and reliability justify
– an environmental check;
– a periodic component conformity check;
– a component check during de-stocking.
Depending on the risk versus cost compromise decision, the periodic check may be replaced
by a check during de-stocking.
6.2 Periodicity
If the stock is not used regularly, it is necessary to carry out a check, the periodicity of which
depends on:
– 14 – IEC 62435-4:2018 © IEC 2018
– the level of risk envisaged;
– the findings of the initial evaluation tests;
– the findings of previous periodic checks.
6.3 Tests during periodic check
Generally, the tests or measurements will be made
– on a representative sample of the components stored;
– on the same samples, in order to avoid stresses caused by handling and test operations;
– in compliance with the specifications and quality levels used during procurement;
– following the electrical parameters identified as critical;
– following the expected risk versus cost compromise parameters.
7 Removal from storage
7.1 Precautions
It is important not to interrupt the chain of precautions taken against certain effects of storage,
such as temperature variations, relative humidity, aggression, contaminations, electrostatic
discharges, radiation and light.
Any component removed from storage can only be stored again if the storage rules provided
for this type of component are adhered to again. However, the initial storage period shall be
taken into account and any required pre-storage routines should be adhered to.
If any packaged electronic device (part) or unpackaged semiconductor is removed from
storage (exposed), it shall be handled in accordance with the manufacturer's
recommendations for ESD and (if moisture sensitive) moisture control. Unless otherwise
allowed by the device's storage temperature, the temperature shall be maintained between
5 °C and 40 °C. Unpackaged semiconductors shall not be removed from their sealed
packaging unless the facility has cleanliness, environmental controls and properly
documented processes to assure that, when exposed, the unpackaged semiconductors will
not be degraded due to contamination. Unpackaged semiconductors shall be kept in the
original sealed packaging to the maximum extent practical.
Stock should be controlled by a first-in/first-out distribution industrial practice to avoid
accumulation of vintage components.
7.2 Electrostatic discharges
It is mandatory to perform destocking maintaining the continuity of the conditions. See
IEC 61340-5-2.
8 Materials used in storage regimes
8.1 General
Packing materials that deteriorate with age should not be used, since outgassing of chemicals
and decomposition products could contaminate the product. Use of specific materials for LTS
should be identified and utilized (e.g., closed-cell foams with nitrogen filling).
8.2 Moisture barrier bags (MBB)
Utilization of MBBs with desiccant and HICs for LTS is not limited to MSD hardware. The use
of MBBs is good practice for device protection during LTS. Dry packing has a finite effective
life for moisture protection due to the limited absorption capability of the desiccant and

moisture penetration through the packing material and the moisture barrier bag. Humidity
indicator cards may not be required for non-MSD hardware.
The moisture barrier bag shall be in accordance with MILPRF-81705, TYPE I. Dry pack for
moisture sensitive devices (MSDs) is required in accordance with IEC 60749-20-1 and
J-STD-033.
8.3 Desiccant
The desiccant material shall be capable of removing sources of corrosion and deterioration of
product caused by oxidation, sulfurization, and other processes. The required levels of control
are as follows:
a) Oxygen: < 0,1%
-6
b) Hydrogen sulphide: < 10
-6
c) Sulphur dioxide: < 10
-6
d) Hydrogen chloride: < 10
-6
e) Ammonia: < 10
The desiccant shall be packaged in moisture permeable bags or pouches as determined using
the procedure detailed in IEC 60749-20-1. The MBB rated water vapour transmission rate
(WVTR), bag size and moisture level of non-components that are placed into the MBB are
required for successful calculation of the desiccant required.
8.4 Humidity indicator card (HIC)
Assurance should be made by periodical check of HIC or continuous humidity sensors during
LTS to avoid degradation of components. At the time of this publication JEDEC has
determined that certain bromine-free HICs are useable just over five years. HIC suppliers
should be able to specify the useable life-time. Refer to IEC 60749-20-1 for guidance on the
use of the HIC for storage.
8.5 Dry nitrogen atmosphere
Nitrogen environments of 5 % RH or less shall be in accordance with MIL-PRF-27401, Type 1
Gas, Grade C (99,995 %) and IEC 62258-3. The use of other atmospheric conditions should
be evaluated to ensure performance to LTS requirements.
Nitrogen gas environments shall be in accordance with MIL-PRF-27401, Type 1 Gas, Grade C
(99,995 %).
NOTE Other sources of dry nitrogen are not sufficiently contaminant-free to provide reliable storage.
8.6 High purity dry air atmosphere
Wafer and die may be stored at lower relative humidity while packaged products may be
stored at a minimum relative humidity of greater than 7 % to protect against charge build up
and ESD events.
For wafer and die, dry air meeting the following parameters can be used: 5 % RH 0,04 % CO2,
0,001 % Cl2, 0,001 % S, 0,001 % P. The use of other atmospheric conditions should be
evaluated to ensure performance to LTS requirements.
Dry cabinet storage at 5 % – 10 % RH nominal in dry cabinets may be considered equivalent
to storage in a MBB. Note that open and closing operations result in transient temperature
and humidity excursion that have an associated recovery time to re-establish equilibrium.
Care should be taken to segregate long term storage areas from short term storage areas to
avoid excessive transient humidity exposure that may go as high as 25 %. Finished
components should be stored at greater than 7 % RH to avoid static charge build-up.

– 16 – IEC 62435-4:2018 © IEC 2018
8.7 Storage containers
Packaging materials used and in contact with or in close proximity to the device surface shal
...