ISO 4825-1:2023

Fine ceramics (advanced ceramics, advanced technical ceramics) --Test method for thermal property measurements of metalized ceramic substrates — Part 1: Evaluation of thermal resistance for use in power modules

This document specifies a method for measuring the thermal resistance between a heater chip and a cold plate with the heater chip mounted on a metalized ceramic substrate, imitating a silicon carbide (SiC) high-output power module. This measurement represents an index of the heat dissipation characteristics of a metallized ceramic substrate used in a high-output power module.

Céramiques techniques — Méthode d'essai pour les mesures des propriétés thermiques des substrats céramiques métallisés — Partie 1: Évaluation de la résistance thermique pour utilisation dans les modules d'alimentation

General Information

• Status: Published
• Publication Date: 11-Jan-2023
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: ISO/TC 206 - Fine ceramics
• Drafting Committee: ISO/TC 206/WG 12 - Engineering applications
• Current Stage: 6060 - International Standard published
• Start Date: 12-Jan-2023
• Due Date: 02-Apr-2023
• Completion Date: 12-Jan-2023

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 4825-1
First edition
2023-01
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Test method for thermal property
measurements of metalized ceramic
substrates —
Part 1:
Evaluation of thermal resistance for
use in power modules
Céramiques techniques — Méthode d'essai pour les mesures des
propriétés thermiques des substrats céramiques métallisés —
Partie 1: Évaluation de la résistance thermique pour utilisation dans
les modules d'alimentation
Reference number
ISO 4825-1:2023(E)
© ISO 2023

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ISO 4825-1:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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ISO 4825-1:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Procedure .5
6.1 Set-up. 5
6.2 Test environments . 7
6.3 Measurement . 7
7 Calculation . 8
8 Test report . 8
Annex A (informative) Example of set-up apparatus . 9
Annex B (informative) Interlaboratory evaluation of thermal resistance measurements .10
Bibliography .12
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ISO 4825-1:2023(E)
Foreword
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electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
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Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
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on the ISO list of patent declarations received (see www.iso.org/patents).
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 206, Fine ceramics.
A list of all parts in the ISO 4825 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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ISO 4825-1:2023(E)
Introduction
Electrical energy is predicted to become an increasingly major modality of energy usage in the future,
and power conversion technologies play a crucial role in its generation, transmission, storage and
use. Against this backdrop, power modules that use semiconductor devices to provide high-efficiency
conversion and control of electric power are becoming an extremely important technology. While
silicon has long been used as the primary material for power semiconductor devices, wide bandgap
semiconductors using SiC, GaN and other such materials as next-generation power semiconductors
are drawing increasing expectations for their prospects of greater energy conservation, higher output
and high-speed operation. Power modules using next-generation power semiconductors of this type
are also anticipated to provide higher output and higher energy density, and likewise to capitalize
on the characteristics of these materials for high-temperature operation (in the near future, junction
temperatures are anticipated to reach 250 °C), thus heat-dissipating technologies are becoming more
important than ever before.
In high-output power modules, an insulating substrate serving as an electrical insulator is one of the
most important component materials. As power semiconductor devices increase in power output and
energy density, the amount and density of heat dissipated by these devices are also increasing, creating
a demand for higher thermal conductivity in substrate. For this reason, ceramics are generally used as
insulating substrates because of their high thermal conductivity. In addition, to minimize interfacial
thermal resistance between constituent materials, metallic conductor circuit layers are also joined
to ceramic substrates at high temperature. Heat-dissipating structures of this nature are termed
metallized ceramic substrates.
Techniques are available to measure the thermal conductivity of the individual materials comprising
metallized ceramic substrates; however, there are no established methods to evaluate the thermal
characteristics of metallized ceramic substrates per se, or the thermal characteristics of power
semiconductor devices in mounted form, which are key issues in the design of power modules with a
high heat-dissipating efficiency.
This document provides a technique for bonding a metallized ceramic substrate equipped with a heater
chip to a cold plate and for using the amount of heat dissipated by the heater chip and the temperature
differential between the heater chip and the cold plate to measure the thermal resistance of a system
including a metallized ceramic substrate. Manufacturers of ceramic elements, modules and other such
devices can use this standard to evaluate the heat-dissipating characteristics of metallized ceramic
substrates under common conditions.
The International Organization for Standardization (ISO) draws attention to the fact that it is claimed
that compliance with this document may involve the use of a patent.
ISO takes no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured ISO that he/she is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In
this respect, the statement of the holder of this patent right is registered with ISO. Information may be
obtained from the patent database available at www.iso.org/patents.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights other than those in the patent database. ISO shall not be held responsible for identifying
any or all such patent rights.
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INTERNATIONAL STANDARD ISO 4825-1:2023(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for thermal property
measurements of metalized ceramic substrates —
Part 1:
Evaluation of thermal resistance for use in power modules
1 Scope
This document specifies a method for measuring the thermal resistance between a heater chip and a
cold plate with the heater chip mounted on a metalized ceramic substrate, imitating a silicon carbide
(SiC) high-output power module. This measurement represents an index of the heat dissipation
characteristics of a metallized ceramic substrate used in a high-output power module.
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.
ISO 554, Standard atmospheres for conditioning and/or testing — Specifications
IEC 60584-1, Thermocouples — Part 1: EMF specifications and tolerances
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
metalized ceramic substrate
component in which metallic circuit layers are joined to a ceramic substrate
3.2
thermal resistance
thermal property representing resistance to heat flow from a higher temperature area to a lower
temperature area in a structure
Note 1 to entry: In this document thermal resistance is expressed as the temperature difference in the structure
across a thickness when a unit of heat energy flows through it in unit time. The SI unit of thermal resistance is
K/W.
[SOURCE: IEC 60747-15:2010, 3.1, modified — Definition revised and note to entry added.]
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ISO 4825-1:2023(E)
3.3
thermal conductivity
quotient of the amount of heat flow per unit of time through a unit of surface area perpendicular to
the heat flow in a solid material, divided by the temperature difference per unit length (temperature
gradient)
Note 1 to entry: The SI unit of thermal conductivity is W/(m·K).
3.4
thermal interface material
TIM
material which fills small gaps or irregularities between components and has the function of efficiently
transferring heat produced by a device to a heat-dissipating component
EXAMPLE Thermally conductive greases, silicone sheets, graphite sheets.
4 Principle
The thermal resistance between a heater chip and a cold plate in a direction perpendicular to the
substrate is calculated by dividing the temperature difference between the heater chip and the cold
plate by the amount of heat radiated from the heater chip in a structure where a metalized ceramic
substrate bearing the heater chip is bonded to the cold plate. The cold plate is temperature-controlled
by a chiller. This calculation method minimizes the error in thermal resistance value that develops
as the aforementioned temperature difference increases. An interlaboratory comparison study
(interlaboratory test) project on this method is described in Annex B.
5 Apparatus
Figure 1 presents a schematic of the test apparatus, which is composed of the following main elements.
Note See Annex A for an example of a detailed set-up for thermal resistance measurement.
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ISO 4825-1:2023(E)
Key
1 metalized ceramic substrate 7 thermocouple
2 heater chip 8 temperature sensor
3 cold plate 9 supply of electricity
4 chiller 10 recording voltage and electric current
5 power supply 11 turning on/off power
6 controller and recorder
Figure 1 — Illustration of thermal resistance measurement apparatus
5.1 Metalized ceramic substrate. Unless otherwise specified, use a metalized ceramic substrate
with a configuration as shown in Figure 2. The metallic pattern on the front of the metallized ceramic
substrate shall include an installation area for bonding the heater chip and at least four electrode pads
electrically insulated from this area. The entire back of the metallized ceramic substrate shall comprise
a metal layer. The thickness of the metallized ceramic substrate and the metal layer are not stipulated
specifically.
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ISO 4825-1:2023(E)
Dimensions in millimetres
a) Schematic from the top b) Schematic from the back
c) Schematic from the side
Key
1 electrode pad (metal) 4 ceramic substrate
2 metal layer (front) 5 adhesion location for heater chip
3 metal layer (back)
Figure 2 — Configuration of metalized cera
...