IEC TS 62607-2-6:2024

Nanomanufacturing - Key control characteristics - Part 2-6: Carbon nanotube-related products - Thermal diffusivity of vertically-aligned carbon nanotubes: flash method

IEC TS 62607-2-6:2024 which is a technical specification, specifies a protocol for determining the key control characteristic
- thermal diffusivity
for vertically-aligned carbon nanotube (VACNT) films grown on solid substrates by
- flash method.
A light pulse from a flash lamp or a laser is irradiated onto the front surface (substrate side) of the VACNT film on solid substrates. Then, the temperature change of the other side of the specimen is monitored in real time after the pulse irradiation. The thermal diffusivity of the VACNT film can be analysed from the time variation of this temperature change.
- This method is applicable for evaluating the thermal transport properties of the VACNT films that can be used as thermal interface materials in electronics assembly.

General Information

• Status: Published
• Publication Date: 06-Aug-2024
• ICS: 07.120 - Nanotechnologies
• Technical Committee: TC 113 - Nanotechnology for electrotechnical products and systems
• Drafting Committee: WG 8 - TC 113/WG 8
• Current Stage: PPUB - Publication issued
• Start Date: 07-Aug-2024
• Completion Date: 16-Aug-2024

Overview

IEC TS 62607-2-6:2024 is a Technical Specification in the IEC 62607 series on nanomanufacturing. It defines a standardized protocol to determine the thermal diffusivity of vertically‑aligned carbon nanotube (VACNT) films grown on solid substrates using the flash method. The method irradiates a light pulse (flash lamp or laser) onto the substrate side of a VACNT/substrate bilayer and records the transient temperature response on the rear face to extract thermal transport properties relevant to thermal interface materials in electronics.

Key topics and requirements

• Measurement principle: front-side pulse heating with real‑time monitoring of rear-surface temperature; thermal diffusivity derived from the time‑dependent temperature rise.
• Specimen geometry: VACNT film tightly bound to a solid substrate (bilayer configuration), not free‑standing samples.
• Pre-measurement characterization:
  • Thickness (h) and mass density (ρ) of the VACNT film.
  • Surface preparation and optional coating of the substrate side to ensure consistent absorption of the incident pulse.
• Instrumentation and pulse:
  • Use of a flash lamp or laser as the incident light pulse; control of pulse energy, duration and uniformity is required.
• Temperature detection: real‑time measurement of rear-face transient temperature with suitable sensors (e.g., IR detectors), ensuring time resolution and calibration are adequate.
• Measurement environment: control of ambient conditions to reduce convective and radiative artifacts.
• Data analysis:
  • Application of a bilayer analytical model tailored for a VACNT film on substrate to extract film thermal diffusivity (α).
  • Procedures for calculating thermal conductivity (k) from α using volumetric heat capacity where applicable.
• Reporting: standardized reporting format including specimen parameters, measurement conditions, raw transient data, analysis method and uncertainty.
• Informative annexes: case study for VACNT on Si substrates and guidance on estimating thermal conductivity from measured diffusivity.

Applications and who uses this standard

• Designed for research laboratories, materials characterization facilities, and quality control groups in industries developing VACNT-based thermal interface materials (TIMs).
• Useful to electronics manufacturers, thermal management engineers, and nanomaterials producers who need standardized, comparable thermal-property data for integration and performance assessment.
• Valuable for standards bodies and metrology labs establishing interlaboratory comparisons and traceable measurement protocols.

Related standards

• IEC TS 62607-2-5:2022 - Mass density of VACNTs (X‑ray absorption method)
• ISO 18755:2022 - Flash method for thermal diffusivity of monolithic ceramics (methodology reference)

Keywords: IEC TS 62607-2-6:2024, thermal diffusivity, vertically‑aligned carbon nanotubes, VACNT, flash method, thermal interface materials, nanomanufacturing, carbon nanotube products.

Standards Content (Sample)

IEC TS 62607-2-6 ®
Edition 1.0 2024-08
TECHNICAL
SPECIFICATION
colour
inside
Nanomanufacturing – Key control characteristics –
Part 2-6: Carbon nanotube-related products – Thermal diffusivity of vertically-
aligned carbon nanotubes: flash method

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IEC TS 62607-2-6 ®
Edition 1.0 2024-08
TECHNICAL
SPECIFICATION
colour
inside
Nanomanufacturing – Key control characteristics –

Part 2-6: Carbon nanotube-related products – Thermal diffusivity of vertically-

aligned carbon nanotubes: flash method

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 07.120  ISBN 978-2-8322-9455-0

– 2 – IEC TS 62607-2-6:2024 © IEC 2024
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 8
4 Measurement of thermal diffusivity of vertically-aligned carbon nanotubes on solid
substrates with flash method . 8
4.1 General . 8
4.2 Measurement principle . 9
4.3 Thickness and mass density measurement for VACNT film . 10
4.4 Coating substrate surface . 10
4.5 Incident light pulse . 10
4.6 Temperature measurement at the rear surface of sample . 10
4.7 Measurement environment . 11
5 Data analysis . 11
5.1 Bilayer analytical model . 11
5.2 Evaluation of thermal diffusivity of VACNT film . 11
6 Reporting. 11
Annex A (informative) Case study of thermal diffusivity measurements for vertically-
aligned carbon nanotubes grown on Si substrates . 13
A.1 General . 13
A.2 Sample preparation for VACNTs . 13
A.3 Result of flash measurements for VACNT samples . 14
A.4 Analytical solution of transient temperature rise for bilayer sample measured
with flash method . 17
Annex B (informative) Estimating thermal conductivity values of VACNTs . 18
Bibliography . 19

Figure 1 – Schematic diagram of flash method for VACNT film on substrate . 9
Figure 2 – Typical transient temperature curve for VACNT film on substrate . 9
Figure A.1 – Cross-sectional scanning electron microscope images of vertically-aligned
carbon nanotube films on Si substrates. 14
Figure A.2 – Normalized transient temperature curves measured for vertically-aligned
carbon nanotube films on Si substrates. 16

Table 1 – Example table format for reporting . 12
Table A.1 – Physical parameters obtained from VACNT samples . 17

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NANOMANUFACTURING –
KEY CONTROL CHARACTERISTICS –
Part 2-6: Carbon nanotube-related products –
Thermal diffusivity of vertically-aligned carbon nanotubes: flash method

FOREWORD
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IEC TS 62607-2-6 has been prepared by IEC technical committee 113: Nanotechnology for
electrotechnical products and systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
113/823/DTS 113/845/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
– 4 – IEC TS 62607-2-6:2024 © IEC 2024
The language used for the development of this Technical Specification is English.
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/publications.
A list of all parts in the IEC 62607 series, published under the general title Nanomanufacturing
– Key control characteristics, 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, or
• revised.
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INTRODUCTION
Vertically-aligned carbon nanotubes (VACNTs) possess array structures, in which nanotubes
are oriented in the perpendicular direction to a substrate surface. Chemical vapour deposition
(CVD) is one of the common methods for the synthesis of VACNTs, where CNTs can be grown
in the presence of metal catalysts, via thermal decomposition of hydrocarbon sources such as
methane, ethylene, acetylene, ethanol, and so on. VACNTs are promising as thermal interface
materials in electronics assembly owing to their high thermal conductivity, desirable mechanical
properties, and good stability. Thermal transport properties in VACNT films really depend on
their distribution and alignment behaviours of individual nanotubes, disorders such as defects
and impurities.
Thermal diffusivity is one of the key parameters that govern thermal transport properties in solid
materials. Flash method is a well-established, standard technique for measuring the thermal
diffusivity. Originally, flash method was applicable to homogeneous monolithic (single layer)
samples. In fact, some previous works reported thermal diffusivity measurements for self-
standing VACNTs that were peeled off from the substrates after the CNT growth. However,
VACNT films will be tightly connected to solid substrates in possible practical applications such
as thermal interface materials. This means that flash method can not be simply applied to
VACNT films grown on solid substrates. Hence, there is a need for new reliable protocols based
on flash method for evaluating thermal diffusivity of VACNT films on solid substrates. This
document specifies standardized protocols for measuring thermal diffusivity of VACNTs grown
on solid substrates with flash method, where the specimen is a bilayer of the VACNT film and
the substrate.
– 6 – IEC TS 62607-2-6:2024 © IEC 2024
NANOMANUFACTURING –
KEY CONTROL CHARACTERISTICS –
Part 2-6: Carbon nanotube-related products –
Thermal diffusivity of vertically-aligned carbon nanotubes: flash method

1 Scope
This part of IEC 62607 specifies a protocol for determining the key control characteristic
• thermal diffusivity
for vertically-aligned carbon nanotube (VACNT) films grown on solid substrates by
• flash method.
A light pulse from a flash lamp or a laser is irradiated onto the front surface (substrate side) of
the VACNT film on solid substrates. Then, the temperature change of the other side of the
specimen is monitored in real time after the pulse irradiation. The thermal diffusivity of the
VACNT film can be analysed from the time variation of this temperature change.
– This method is applicable for evaluating the thermal transport properties of the VACNT films
that can be used as thermal interface materials in electronics assembly.
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 TS 62607-2-5:2022, Nanomanufacturing – Key control characteristics – Carbon nanotube
materials – Mass density of vertically-aligned carbon nanotubes: X-ray absorption method
ISO 18755:2022, Fine ceramics (advanced ceramics, advanced technical ceramics) –
Determination of thermal diffusivity of monolithic ceramics by flash method
3 Terms, definitions and abbreviated terms
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 Terms and definitions
3.1.1
carbon nanotube
CNT
nanotube composed of carbon
[SOURCE: ISO/TS 80004-3:2020, 3.3.3, modified – Note 1 to entry has been deleted.]
3.1.2
vertically-aligned carbon nanotubes
VACNTs
carbon nanotube bundle grown in the perpendicular direction to a substrate surface
[SOURCE: IEC TS 62607-2-5:2022, 3.1.4]
3.1.3
thickness
h
dimension of the test specimen in the direction of heat transfer measurement
[SOURCE: ISO 19629:2018, 3.3]
3.1.4
mass density
ρ
at a given point within a three-dimensional domain of quasi-infinitesimal volume dV, scalar
quantity equal to the mass dm within the domain divided by the volume dV
ρ = dm/dV
[SOURCE: IEC 60050-113:2011, 113-03-07, modified – The formula has been moved to a new
line.]
3.1.5
specific heat capacity
C
heat capacity divided by mass
[SOURCE: IEC 60050-113:2011, 113-04-48, modified – The formula and Notes have been
deleted.]
3.1.6
volumetric heat capacity
heat capacity divided by volume
3.1.7
thermal diffusivity
α
thermal conductivity divided by the volumetric heat capacity

– 8 – IEC TS 62607-2-6:2024 © IEC 2024
3.1.8
thermal conductivity
k
density of heat flow rate divided by temperature gradient under steady state condition
Note 1 to entry: Thermal conductivity is calculated by using the equation k = αρC.
[SOURCE: ISO 18755:2005, 3.2, modified – Note 1 to entry has been added.]
3.1.9
thermal effusivity
b
heat transport property given by the product of volumetric heat capacity and square root of
thermal diffusivity
3.1.10
thermal diffusion time
...