IEC TR 62878-2-8:2021

Device embedding assembly technology - Part 2-8: Guidelines - Warpage control of active device embedded substrate

IEC TR 62878-2-8:2021(E) 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.

General Information

• Status: Published
• Publication Date: 06-Jul-2021
• ICS: 31.180 - Printed circuits and boards
• ICS: 31.190 - Electronic component assemblies
• Technical Committee: TC 91 - Electronics assembly technology
• Drafting Committee: WG 6 - TC 91/WG 6
• Current Stage: PPUB - Publication issued
• Start Date: 26-Jul-2021
• Completion Date: 07-Jul-2021

Standards Content (Sample)

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
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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
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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.
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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
...