IEC TR 62878-2-8:2021

IEC TR 62878-2-8 ®
Edition 1.0 2021-07
TECHNICAL
REPORT
colour
inside
Device embedding assembly technology –
Part 2-8: Guidelines – Warpage control of active device embedded substrate
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always
committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 000 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 18 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc

If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC TR 62878-2-8 ®
Edition 1.0 2021-07
TECHNICAL
REPORT
colour
inside
Device embedding assembly technology –

Part 2-8: Guidelines – Warpage control of active device embedded substrate

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.180; 31.190 ISBN 978-2-8322-9953-1

– 2 – IEC TR 62878-2-8:2021 © IEC 2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Warpage driving force and resistance . 6
4.1 General . 6
4.2 Warpage driving force . 6
4.3 Warpage resistance . 6
4.4 Determining parameters . 7
5 Guideline for warpage of active device embedded substrate . 9
5.1 General . 9
5.2 Rigidity . 9
5.3 Neutral axis . 9
5.4 Typical example of low rigidity case . 10
5.5 Typical example of high rigidity case . 11
6 Conclusion . 13
Bibliography . 14

Figure 1 – Warpage behaviour of device embedded substrate during heating and
cooling . 6
Figure 2 – Relationship between warpage and rigidity . 7
Figure 3 – Parameters determining warpage . 7
Figure 4 – Effects of dummy Cu design on warpage . 8
Figure 5 – Neutral axis of device embedded substrate . 9
Figure 6 – Warpage behaviour of active device embedded substrate during heating
and cooling . 10
Figure 7 – Measured and simulated warpage results of die embedded substrates with
low rigidity . 11
Figure 8 – Structure of die embedded package with high rigidity . 12
Figure 9 – Simulated results on effect of die thickness on die embedded package
warpage . 12

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DEVICE EMBEDDING ASSEMBLY TECHNOLOGY –

Part 2-8: Guidelines –
Warpage control of active device embedded substrate

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
in the subject dealt with may participate in this preparatory work. International, governmental and non-
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
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
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
Publications.
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.
IEC TR 62878-2-8, which is a technical report, has been prepared by IEC technical committee
91: Electronics assembly technology.
The text of this Technical Report is based on the following documents:
Draft Report on voting
91/1649/DTR 91/1721/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.

– 4 – IEC TR 62878-2-8:2021 © IEC 2021
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,
available at www.iec.ch/members_experts/refdocs. The main document types developed by
IEC are described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts in the IEC 62878 series, published under the general title Device embedding
assembly technology, 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 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

DEVICE EMBEDDING ASSEMBLY TECHNOLOGY –

Part 2-8: Guidelines –
Warpage control of active device embedded substrate

1 Scope
This part of IEC 62878 describes a warpage control of active device embedded substrate
along with parameters for determining warpage, which are useful during package assembly.
Warpage results are explained using warpage driving force, resistance and neutral axis, for
typical die embedded substrate, where the discrete active dies are placed in the core of
substrate and interconnected to the substrate by direct Cu bonding. The same principles are
applicable in other device embedded substrates. Even though the detailed structure of other
device embedded substrates might be different, the origin and determination of the
parameters of warpage are the same and thus the purpose of this report is to help engineers
improve the warpage behaviours of their products by applying this principle.
2 Normative references
IEC 60194 (all parts), Printed boards design, manufacture and assembly – Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60194 and the
following 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
warpage
deviation from uniform flatness of the substrate for the range of thermal conditions
experienced during the package to board assembly
Note 1 to entry: Warpage during board assembly can cause the device terminals to have open or short circuit
connections after the reflow soldering operation. Certain package types, such as BGAs (ball grid arrays), have
been found to be more susceptible to component warpage [1] .
Note 2 to entry: Package warpage depends on many factors including CTE mismatch between device
constituents, assembly process, package design geometries, top and embedded die, substrate, etc. (x, y, & z). In
addition, it can be related with use of IHS (integrated heat spreader), stiffener, or overmold (geometries and
material choices include sealant/adhesives used), and other technology aspects of embedded design, embedded
and external caps, use of GaA vs. SiO2, etc.
—————————
Numbers in square brackets refer to the Bibliography.

– 6 – IEC TR 62878-2-8:2021 © IEC 2021
4 Warpage driving force and resistance
4.1 General
Warpage of device embedded substrate can be related with many parameters which include
properties, thickness, Cu ratio, routing and process history. The dimensions of embedded die
including t
...