IEC 60749-20-1:2009

IEC 60749-20-1 ®
Edition 1.0 2009-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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

Dispositifs à semiconducteurs – Méthodes d'essais mécaniques et climatiques –
Partie 20-1: Manipulation, emballage, étiquetage et transport des composants
pour montage en surface sensibles à l'effet combiné de l'humidité et de la
chaleur de brasage
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IEC 60749-20-1 ®
Edition 1.0 2009-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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

Dispositifs à semiconducteurs – Méthodes d'essais mécaniques et climatiques –
Partie 20-1: Manipulation, emballage, étiquetage et transport des composants
pour montage en surface sensibles à l'effet combiné de l'humidité et de la
chaleur de brasage
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
V
CODE PRIX
ICS 31.080.01 ISBN 978-2-88910-285-3
– 2 – 60749-20-1 © IEC:2009
CONTENTS
FOREWORD.4

INTRODUCTION.6

1 Scope.7

2 Normative references .7

3 Terms and definitions .7

4 General applicability and reliability considerations.9

4.1 Assembly processes.9

4.1.1 Mass reflow .9
4.1.2 Localized heating .9
4.1.3 Socketed components .9
4.1.4 Point-to-point soldering .9
4.2 Reliability .9
5 Dry packing .10
5.1 Requirements.10
5.2 Drying of SMDs and carrier materials before being sealed in MBBs.10
5.2.1 Drying requirements - level A2.10
5.2.2 Drying requirements - levels B2a to B5a.10
5.2.3 Drying requirements - carrier materials .10
5.2.4 Drying requirements - other .11
5.2.5 Excess time between bake and bag.11
5.3 Dry pack.11
5.3.1 Description .11
5.3.2 Materials .11
5.3.3 Labels .13
5.3.4 Shelf life .14
6 Drying .14
6.1 Drying options .14
6.2 Post exposure to factory ambient .16
6.2.1 Floor life clock .16
6.2.2 Any duration exposure.16
6.2.3 Short duration exposure .16
6.3 General considerations for baking .17

6.3.1 High-temperature carriers.17
6.3.2 Low-temperature carriers.17
6.3.3 Paper and plastic container items .17
6.3.4 Bakeout times.17
6.3.5 ESD protection .17
6.3.6 Reuse of carriers .17
6.3.7 Solderability limitations.17
7 Use .18
7.1 Floor life clock start .18
7.2 Incoming bag inspection.18
7.2.1 Upon receipt.18
7.2.2 Component inspection .18
7.3 Floor life.18
7.4 Safe storage.19

60749-20-1 © IEC:2009 – 3 –
7.4.1 Safe storage categories.19

7.4.2 Dry pack.19

7.4.3 Dry atmosphere cabinet.19

7.5 Reflow.19

7.5.1 Reflow categories .19

7.5.2 Opened MBB .19

7.5.3 Reflow temperature extremes .19

7.5.4 Additional thermal profile parameters .20

7.5.5 Multiple reflow passes .20

7.5.6 Maximum reflow passes .20

7.6 Drying indicators .20
7.6.1 Drying requirements .20
7.6.2 Excess humidity in the dry pack.20
7.6.3 Floor life or ambient temperature/humidity exceeded.21
7.6.4 Level B6 SMDs.21
Annex A (normative) Symbol and labels for moisture-sensitive devices.22
Annex B (informative) Board rework.27
Annex C (informative) Derating due to factory environmental conditions .28
Bibliography.31

Figure 1 – Typical dry pack configuration for moisture-sensitive SMDs in shipping
tubes .11
Figure 2a – Example humidity indicator card for level A2 .13
Figure 2b – Example humidity indicator card for levels B2a to B5a .13
Figure 2 – Example humidity indicator cards .13
Figure A.1 – Moisture-sensitive symbol (example) .22
Figure A.2 – MSID label (example) .22
Figure A.3 – Information label for level A1 or B1 (example).23
Figure A.4 – Moisture-sensitive caution label for level A2 (example) .24
Figure A.5 – Moisture-sensitive caution label for levels B2-B5a (example) .25
Figure A.6 – Moisture-sensitive caution label for level B6 (example) .26

Table 1 – Dry packing requirements.10
Table 2 – Reference conditions for drying mounted or unmounted SMDs (user bake:
floor life begins counting at time = 0 after bake).14
Table 3 – Default baking times used prior to dry-pack that were exposed to conditions
≤60 % RH (supplier bake: MET = 24 h) .
Table 4 – Moisture classification level and floor life .18
Table C.1 – Recommended equivalent total floor life (days) for level A2 at 20 °C, 25 °C,
30 °C and 35 °C for ICs with Novolac, biphenyl and multifunctional epoxies (reflow at
same temperature at which component was classified) .28
Table C.2 – Recommended equivalent total floor life (days) for levels B2a to B5a at
20 °C, 25 °C, 30 °C and 35 °C for ICs with Novolac, biphenyl and multifunctional
epoxies (reflow at same temperature at which component was classified).29

– 4 – 60749-20-1 © IEC:2009
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
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

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
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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 60749-20-1 has been prepared by IEC technical committee 47:
Semiconductor devices.
This standard cancels and replaces IEC/PAS 62168 and IEC/PAS 62169 published in 2000.
IEC/PAS 62169 was based on a Joint (IPC/JEDEC) Industry Standard. This first edition of
IEC 60749-20-1 constitutes a technical revision.

60749-20-1 © IEC:2009 – 5 –
The text of this standard is based on the following documents:

FDIS Report on voting
47/2010/FDIS 47/2013/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 the 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 maintenance result 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.
– 6 – 60749-20-1 © IEC:2009
INTRODUCTION
The advent of surface-mount devices (SMDs) introduced a new class of quality and reliability

concerns regarding package damage ‘‘cracks and delamination’’ from the solder reflow

process. This document describes the standardized levels of floor life exposure for

moisture/reflow-sensitive SMDs along with the handling, packing and shipping requirements

necessary to avoid moisture/reflow-related failures. IEC 60749-20 defines the classification

procedure and Annex A of this document defines the labelling requirements.

Moisture from atmospheric humidity enters permeable packaging materials by diffusion.

Assembly processes used to solder SMDs to printed circuit boards (PCBs) expose the entire

package body to temperatures higher than 200 °C. During solder reflow, the combination of
rapid moisture expansion, materials mismatch, and material interface degradation can result
in package cracking and/or delamination of critical interfaces within the package.
The solder reflow processes of concern are convection, convection/IR, infrared (IR), vapour
phase (VPR) and hot air rework tools. The use of assembly processes that immerse the
component body in molten solder are not recommended for most SMDs.
This first edition of IEC 60749-20-1 is based principally on IPC/JEDEC J-STD-033 and the
permission to use this standard is gratefully acknowledged. It is also based on contributing
documents from various national committees.

___________
Refer to Bibliography.
60749-20-1 © IEC:2009 – 7 –
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

1 Scope
This part of IEC 60749 applies to all non-hermetic SMD packages which are subjected to
reflow solder processes and which are exposed to the ambient air.
The purpose of this document is to provide SMD manufacturers and users with standardized
methods for handling, packing, shipping, and use of moisture/reflow sensitive SMDs which
have been classified to the levels defined in IEC 60749-20. These methods are provided to
avoid damage from moisture absorption and exposure to solder reflow temperatures that can
result in yield and reliability degradation. By using these procedures, safe and damage-free
reflow can be achieved, with the dry packing process, providing a minimum shelf life
capability in sealed dry-bags from the seal date.
Two test conditions, method A and method B, are specified in the soldering heat test of
IEC 60749-20. For method A, moisture soak conditions are specified on the assumption that
moisture content inside the moisture barrier bag is less than 30 % RH. For method B,
moisture soaking conditions are specified on the assumption that manufacturer’s exposure
time (MET) does not exceed 24 h and the moisture content inside the moisture barrier bag is
less than 10 % RH. In an actual handling environment, SMDs tested by method A are
permitted to absorb moisture up to 30 % RH, and SMDs tested by method B are permitted to
absorb moisture up to 10 % RH. This standard specifies the handling conditions for SMDs
subjected to the above test conditions.
NOTE Hermetic SMD packages are not moisture sensitive and do not require moisture precautionary handling.
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 60749-20, Semiconductor devices – Mechanical and climatic test methods – Part 20:
Resistance of plastic-encapsulated SMDs to the combined effect of moisture and soldering
heat
IEC 60749-30, Semiconductor devices – Mechanical and climatic test methods – Part 30:
Preconditioning of non-hermetic surface mount devices prior to reliability testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
active desiccant
desiccant that is either fresh (new) or has been baked according to the manufacturer’s
recommendations to renew it to original specifications

– 8 – 60749-20-1 © IEC:2009
3.2
bar code label
a label that gives information in a code consisting of parallel bars and spaces, each of various

specific widths
NOTE For the purposes of this standard, the bar code label is on the lowest level shipping container and includes
information that describes the product, e.g., part number, quantity, lot information, supplier identification, and
moisture-sensitivity level etc.

3.3
mass reflow
reflow of a number of components with simultaneous attachment by an infrared (IR),

convection/IR, convection, or vapour phase reflow (VPR) process
3.4
carrier
container that directly holds components such as a tray, tube, or tape and reel
3.5
desiccant
absorbent material used to maintain a low relative humidity
3.6
floor life
allowable time period for a moisture-sensitive device, after removal from a moisture barrier
bag, dry storage or dry bake and before the solder reflow process
3.7
humidity indicator card
HIC
card on which a moisture-sensitive chemical is applied in such a way that it will make a
significant, perceptible change in colour (hue), typically from blue (dry) to pink (wet) when the
indicated relative humidity is exceeded
NOTE The HIC is packed inside the moisture-barrier bag, along with a desiccant, to aid in determining the level of
moisture to which the moisture-sensitive devices have been subjected.
3.8
manufacturer’s exposure time
MET
maximum time after bake that the component manufacturer requires to process components
prior to bag seal; it also includes the maximum time allowed at the distributor for having the
bag open to split out smaller shipments

3.9
moisture barrier bag
MBB
bag designed to restrict the transmission of water vapour and used to pack moisture-sensitive
devices
3.10
rework
the removal of a component for scrap, reuse, or failure analysis; the replacement of an
attached component; or the heating and repositioning of a previously attached component
3.11
shelf-life
maximum storage period for a dry-packed moisture-sensitive device in an unopened moisture
barrier bag (MBB) to avoid exceeding the specified interior bag ambient humidity

60749-20-1 © IEC:2009 – 9 –
3.12
surface-mount device
SMD
plastic-encapsulated surface-mount devices made with moisture-permeable materials

NOTE For the purposes of this standard, the term SMD is limited as indicated in the definition.

3.13
solder reflow
a solder attachment process in which previously applied solder or solder paste is melted to

attach a component to the printed circuit board

3.14
water vapour transmission rate
WVTR
measure of the permeability of plastic film or metallized plastic film material to moisture
4 General applicability and reliability considerations
4.1 Assembly processes
4.1.1 Mass reflow
This standard applies to mass solder reflow assembly by convection, convection/IR, infrared
(IR), and vapour phase (VPR), processes. It does not apply to mass solder reflow processes
that immerse the component bodies in molten solder (e.g., wave soldering bottom mounted
components). Such processes are not allowed for many SMDs and are not covered by the
component qualifications standards used as a basis for this document.
4.1.2 Localized heating
This standard also applies to moisture sensitive SMDs that are removed or attached singly by
local ambient heating, i.e., ‘‘hot air rework.’’ See Annex B.
4.1.3 Socketed components
This standard does not apply to SMDs that are socketed and not exposed to solder reflow
temperatures. Such SMDs are not at risk and do not require moisture precautionary handling.
4.1.4 Point-to-point soldering
This standard does not apply to SMDs in which only the leads are heated to reflow the solder,

e.g., hand-soldering, hot bar attach of gull wing leads, and through hole by wave soldering.
The heat absorbed by the SMD body from such operations is typically much lower than for
mass surface mount reflow or hot air rework, and moisture precautionary measures are
typically not needed.
4.2 Reliability
The methods set forth in this specification ensure that an adequate SMD reliability can be
achieved during and after the PCB assembly operation, when the SMDs are evaluated and
verified by IEC 60749-20 and/or by IEC 60749-30, together with environmental reliability
testing.
This specification does not address or ensure solder joint reliability of attached components.

– 10 – 60749-20-1 © IEC:2009
5 Dry packing
5.1 Requirements
Dry packing requirements for the various moisture sensitivity levels are shown in Table 1. The

levels are determined in accordance with IEC 60749-20 and/or IEC 60749-30, together with

reliability testing. As a minimum all materials used in dry packing should conform to relevant

national packaging material standards for ESD-sensitive items.

Table 1 – Dry packing requirements

Dry before
a
Level MBB Desiccant Caution label
MSID label
bag
A1 or B1 Optional Optional Optional Not required Not required if classified at
220 °C to 225 °C
b
Required if classified at other
than 220 °C to 225 °C
A2 or B2 Optional Required Required Required Required
B2a-B5a Required Required Required Required Required
B6 Optional Optional Optional Required Required

a
MSID = Moisture-sensitive identification label.

b
A ‘‘Caution’’ label is not required if level and reflow temperature are given, in human readable form, on the
barcode label attached to the lowest level shipping container.

5.2 Drying of SMDs and carrier materials before being sealed in MBBs
5.2.1 Drying requirements - level A2
Packing of the SMDs classified as Level A2 into MBBs shall be carried out within one week
under the environmental condition below 30 °C/60 % RH after molding, burn-in, or bake.
MET is not specified for Level A2 SMDs.
MBBs may be opened for a short period of time (less than 1 h) and re-closed provided that
the HIC indicates a humidity of less than 30 % RH and provided that the desiccant is replaced
with fresh desiccant. When the MBB is next opened, as long as the HIC indicates below
30 % RH, the duration time of the previous MBB’s opening may be disregarded. Thus, if the
HIC indicates below 30 % RH when MBB is opened, the floor life is not dependent on the
duration time of MBBs opening, and is 168 h at 30 °C/70 % RH.

5.2.2 Drying requirements - levels B2a to B5a
SMDs classified from Levels B2a through to B5a shall be dried (see Clause 6) prior to being
sealed in MBBs. The period between drying and sealing shall not exceed the MET less the
time allowed for distributors to open the bags and repack parts. If the supplier’s actual MET is
more than the default 24 h, then the actual time shall be used. If the distributor practice is to
repack the MBBs with active desiccant, then this time does not need to be subtracted from the
MET.
5.2.3 Drying requirements - carrier materials
The materials from which carriers (such as trays, tubes, reels, etc.) are made can affect the
moisture level when placed in the MBB. Therefore, the effect of these materials shall be
compensated for by baking or, if required, adding additional desiccant in the MBB to ensure
the shelf life of the SMDs (see 6.3).

60749-20-1 © IEC:2009 – 11 –
5.2.4 Drying requirements - other

Suppliers may use the drying effect of normal in-line processes such as post mould cure,

marking cure, and burn-in to reduce the bake time. An equivalency evaluation is

recommended to ensure that high-temperature processing maintains moisture weight gain to

an acceptable level. The total weight gain for the SMD at the time it is sealed in the MBB shall
not exceed the moisture gain of that SMD starting dry and then being exposed to

30 °C/60 % RH for MET h (less the time for distributors).

5.2.5 Excess time between bake and bag

If the allowable time between bake and bag is exceeded, the SMDs shall be redried in

accordance with Clause 6.
5.3 Dry pack
5.3.1 Description
Dry pack consists of desiccant material and a humidity indicator card (HIC) sealed with the
SMDs and their carriers inside a moisture barrier bag (MBB). A representative dry pack
configuration is shown in Figure 1.

Moisture
barrier bag
Dessiccant
pouches
Humidity
Foam
indicator card
end cap
IEC  461/09
Figure 1 – Typical dry pack configuration for moisture-sensitive
SMDs in shipping tubes
5.3.2 Materials
5.3.2.1 Moisture barrier bag (MBB)
The moisture barrier bag shall meet relevant national standard requirements for flexibility,
ESD protection, mechanical strength, and puncture resistance. The bags shall be heat
sealable. The water vapour transmission rate (WVTR) shall be ≤0,03 g/m in 24 h at 40 °C
after flex testing in accordance with relevant national standards governing flex durability of
flexible barrier materials. The WVTR is measured using relevant national standards governing
water vapour transmission rate through plastic film and sheeting using a modulated infrared
sensor.
5.3.2.2 Desiccant
The desiccant material shall comply with relevant national standards governing activated
desiccants used for the static dehumidification of packaging bags. Desiccant shall be dustless,
non-corrosive, and absorbent to amounts specified in the standard. The desiccant shall be

– 12 – 60749-20-1 © IEC:2009
packaged in moisture permeable bags. The amount of desiccant used, per moisture barrier

bag, shall be based on the bag surface area and WVTR in order to maintain an interior

relative humidity in the MBB of less than 30 % at 25 °C for SMD classification A2 and less

than 10 % at 25 °C for SMDs classified from Levels B2a through to B5a.

For comparison between various desiccant types, certain specifications adopted the ‘‘UNIT’’

as the basic unit of measure of quantity for desiccant material. A UNIT of desiccant is defined

as the amount that will absorb a minimum of 2,85 g of water vapour at 20 % RH and 25 °C. To

meet the dry pack requirements of this standard the amount of water vapour that a UNIT of

desiccant can absorb at 10 % RH and 25 °C must be known.

When the desiccant capacity at 10 % RH and 25 °C is known, the following equation should
be used.
U = (0,003 × M × WVTR × A)/D (1)
where
U = amount of desiccant in UNITS;
M = shelf life desired in months;
WVTR = water vapour transmission rate in g/m in 24 h;
A = total surface area of the MBB in m ;
D = amount of water in grams, that a UNIT of desiccant will absorb at 10 % RH and 25 °C.
When the desiccant capacity at 10 % RH and 25 °C is not known, the quantity needed can be
estimated using the following simplified equation.
U = 8 × A (2)
where
U = amount of desiccant in UNITS;
A = total surface area of the MBB in m .
NOTE If trays, tubes, reels, foam end caps, etc., are placed in the bag without baking, additional desiccant will be
required to absorb the moisture contained in these materials.
5.3.2.3 Humidity indicator card (HIC)
The HIC shall comply with relevant national standards governing chemically impregnated
humidity indicator cards. For level A2 the HIC shall have a sensitivity value of 30 % RH which

may be indicated by colour dots with sensitivity values of 20 % RH, 30 % RH, 40 % RH. For
SMDs classified from Levels B2a through to B5a, as a minimum, the HIC shall have 3 colour
dots with sensitivity values of 5 % RH, 10 % RH, 60 % RH. Example HIC are shown in Figure
2a and Figure 2b.
60749-20-1 © IEC:2009 – 13 –
Humidity Indicator
20 % 30 % 40 %
Read at lavender
IEC  462/09
Below 30% RH can be confirmed by comparison of a color (lavender).
Figure 2a – Example humidity indicator card for level A2

HUMIDITY INDICATOR
Complies with IEC 60749-20-1
LEVEL
B2 PARTS
60 %
Bake parts
if 60 % is
NOT blue
LEVEL
B2A-B5A
10 %
PARTS
Bake parts
if 10 % is
NOT blue
5 %
and 5 %
is pink
Initial use: Do not put this card into a bag
if 60 % is pink
IEC  463/09
Figure 2b – Example humidity indicator card for levels B2a to B5a
Figure 2 – Example humidity indicator cards
5.3.3 Labels
5.3.3.1 Labels - Moisture sensitive identification
Labels relevant to the dry pack process are the moisture-sensitive identification (MSID) label
and the caution label as specified in Annex A (see Figures A.2 to A.5). The MSID label shall
be affixed to the lowest-level shipping container that contains the MBB. The Caution label
shall be affixed to the outside surface of the MBB.
5.3.3.2 Labels - Level B6 requirements
Level B6 parts not shipped in MBBs shall have both an MSID label and the appropriate
caution label affixed to the lowest level shipping container.
Manufacturer’s
Lot number
identification
– 14 – 60749-20-1 © IEC:2009
5.3.3.3 Labels - Level A1 and B1 requirements

Level A1 and B1 parts classified for other than from 220 °C to 225 °C maximum reflow

temperature shall have a caution label with the maximum reflow temperature specified. The

caution label shall be affixed to the MBB (if used) or to the lowest-level shipping container.

The caution label will not be required if a bar code label includes the level A1 or B1
classification and maximum reflow temperature information in human readable form. Level A1

and B1 parts classified at from 220 °C to 225 °C maximum reflow temperature do not require

any moisture related labels.
5.3.4 Shelf life
The calculated shelf life for dry packed SMDs shall be a minimum of 12 months from the bag
seal date, when stored in a non-condensing atmospheric environment of <40 °C/90 % RH.
6 Drying
6.1 Drying options
Component drying options for various moisture sensitivity levels and ambient humidity
exposures of ≤60 % RH are given in Tables 2 and 3. Drying using an allowable option resets
the floor life clock. If dried and sealed in an MBB with fresh desiccant, the shelf life is reset.
Tables 2 and 3 give reference conditions for drying SMDs. Table 2 gives conditions for re-
bake of SMDs at a user site after the floor life has expired or other conditions have occurred
to indicate excess moisture exposure. Table 3 gives conditions for bake prior to dry pack at a
supplier and/or distributor and allows for a maximum total of 24 h MET. The supplier shall
formally communicate to the distributor the maximum time that the product may be left
unsealed (at the distributor) before re-baking is required.
Table 2 – Reference conditions for drying mounted or unmounted SMDs (user bake:
floor life begins counting at time = 0 after bake)
Table 2(a) – Level A2
SMD body Bake at 90 °C Bake at 40 °C
Level
Bake at 125 °C
thickness
A2
≤5 % HR ≤5 % HR
Saturated at At limit of floor Saturated at At limit of floor Saturated at At limit of floor
30 °C/85 %RH life + 72 h at 30 °C/85 %RH life + 72 h at 30 °C/85 % life + 72 h at
30 °C/70 % RH 30 °C/70 % RH RH 30 °C/70 % RH
9 h 7 h 33 23 h 13 days 9 days
≤1,4 mm
27 h 17 h 4 days 2 days 37 days 23 days
≤2,0 mm
≤4,5 mm 48 h 48 h 10 days 8 days 79 days 67 days
BGA package 96 h As above per Not applicable As above per Not As above per
>17 mm x 17 mm package package applicable package
or any stacked die thickness and thickness and thickness and
package (See moisture level moisture level moisture level
Note 2)
60749-20-1 © IEC:2009 – 15 –
Table 2(b) – Levels B2a to B5a

SMD body Bake at 90 °C Bake at 40 °C

Level Bake at 125 °C
thickness
≤5 % HR ≤5 % HR
Saturated at At limit of floor Saturated at At limit of floor Saturated at At limit of floor

30 °C/85 %RH life + 72 h at 30 °C/85 %RH life + 72 h at 30 °C/85 % life + 72 h at
30 °C/60 % RH 30 °C/60 % RH RH 30 °C/60 % RH

B2a 7 h 5 h 23 h 13 h 9 days 7 days

B3 9 h 7 h 33 h 23 h 13 days 9 days
≤1,4 mm
B4 11 h 7 h 37 h 23 h 15 days 9 days
B5 12 h 7 h 41 h 24 h 17 days 10 days
B5a 16 h 10 h 54 h 24 h 22 days 10 days
B2a 21 h 16 h 3 days 2 days 29 days 22 days
B3 27 h 17 h 4 days 2 days 37 days 23 days
≤2,0 mm B4 34 h 20 h 5 days 3 days 47 days 28 days
B5 40 h 25 h 6 days 4 days 57 days 35 days
B5a 48 h 40 h 8 days 6 days 79 days 56 days
B2a 48 h 48 h 10 days 7 days 79 days 67 days
B3 48 h 48 h 10 days 8 days 79 days 67 days
B4 48 h 48 h 10 days 10 days 79 days 67 days
≤4,5 mm
B5 48 h 48 h 10 days 10 days 79 days 67 days
B5a 48 h 48 h 10 days 10 days 79 days 67 days
BGA package 2-6 96 h As above per Not applicable As above per Not As above per
package package applicable package
> 17 mm × 17 mm
thickness and thickness and thickness and
or any stacked die
moisture level moisture level moisture level
package (See
Note 2)
NOTE 1 Tables 2(a) and 2(b) are based on worst-case moulded lead frame SMDs. Users may reduce the actual bake time if
technically justified (e.g., absorption/desorption data, etc.). In most cases it is applicable to other non-hermetic SMDs.
NOTE 2 BGA packages >17 mm x 17 mm, that do not have internal planes that block the moisture diffusion path in the substrate, may
use bake times based on the thickness/moisture level portion of the table.

– 16 – 60749-20-1 © IEC:2009
Table 3 – Default baking times used prior to dry-pack that were exposed
to conditions ≤60 % RH (supplier bake: MET = 24 h)

SMD body thickness Level Bake at 125 °C Bake at 150 °C

B2a 8 h 4 h
B3 16 h 8 h
≤ 1,4 mm B4 21 h 10 h
B5 24 h 12 h
B5a 28 h 14 h
B2a 23 h 11 h
B3 43 h 21 h
≤ 2,0 mm B4 48 h 24 h
B5 48 h 24 h
B5a 48 h 24 h
B2a 48 h 24 h
B3 48 h 24 h
≤ 4,5 mm B4 48 h 24 h
B5 48 h 24 h
B5a 48 h 24 h
NOTE The bake times specified are based on worst case conditions and are conditions for a supplier and/or
distributor. Oxidation may occur. Suppliers may reduce the actual bake time if technically justified (e.g., absorption/
desorption data, etc.).
6.2 Post exposure to factory ambient
6.2.1 Floor life clock
Placing SMDs, which have been exposed to factory ambient conditions for greater than 1 h, in
a dry cabinet or dry pack does NOT necessarily stop/pause the floor life clock. However, if the
conditions of 6.2.3 are met the floor life clock can be stopped or reset.
6.2.2 Any duration exposure
Moisture sensitive SMDs which have been exposed only to ambient conditions of ≤60 % RH
for any length of time may be adequately dried by high or low temperature baking according
to Table 2 for rebake prior to reflow or Table 3 for drying prior to dry pack.
6.2.3 Short duration exposure
6.2.3.1 General considerations for short duration exposure

Previously dry SMDs, which have been exposed only to ambient conditions not exceeding
30 °
...