ISO 25245:2026

• Abstract:

  This document specifies the method of the peel test using a tensile testing machine to evaluate the adhesion strength of metallic coatings on plastic substrates under controlled temperatures. It also specifies the designations of the peel test results. The designation consists of the adhesion of metallic coatings to the substrate and test temperature, as well as the substrate material and the principal component, manufacturing process and thickness of the metallic coatings.

• Status: Published
• Publication Date: 22-Sep-2026
• ICS: 25.220.40 - Metallic coatings
• ICS: 83.080.01 - Plastics in general
• Technical Committee: ISO/TC 107 - Metallic and other inorganic coatings
• Drafting Committee: ISO/TC 107 - Metallic and other inorganic coatings
• Current Stage: 6060 - International Standard published
• Start Date: 23-Sep-2026
• Due Date: 16-Aug-2027
• Completion Date: 23-Sep-2026

ISO 25245:2026 is an International Standard from ISO for measuring the peel strength of metallic coatings on plastic substrates under controlled temperatures. It specifies a tensile-test-machine peel method and a designation system that records the substrate, coating type, coating thickness, test temperature and measured adhesion strength. It is intended for laboratories, manufacturers, quality teams and buyers who need comparable numerical adhesion data for metal-coated plastics.

What does ISO 25245:2026 specify?

ISO 25245:2026 specifies the peel test method for evaluating the adhesion strength of metallic coatings on plastic substrates when the test is carried out under controlled temperatures. It also specifies how to designate the test result so the report identifies the coating system, the substrate, the test temperature and the measured peel strength.

The document is organized into scope, normative references, terms and definitions, test method, designation and test report. It then adds three informative annexes with practical examples and chamber guidance.

Annex	What it covers
Annex A	Thermostatic chamber, including high-temperature and low-temperature arrangements
Annex B	Round-robin examples for peel testing on PBT, including effects of seed layer, coating thickness, strip width and peeling speed
Annex C	Effects of test temperature on peel strength, using PBT specimens

What are the key requirements of ISO 25245:2026?

ISO 25245:2026 requires a controlled peel test setup, defined specimen preparation, fixed test conditions and a structured result designation. In practice, the standard aims to make peel results repeatable and comparable across laboratories and temperature conditions.

Test setup and equipment

ISO 25245:2026 uses a tensile testing machine that continuously records peel force. The specimen holder shall keep the peeling direction at 90°, and the machine shall be integrated with a thermostatic chamber when the test is run under controlled temperature.

That matters because peel angle and temperature both affect the measured adhesion. If either is inconsistent, the result can shift even when the coating is unchanged.

Specimen preparation

ISO 25245:2026 recommends flat specimens cut from the product, with a recommended size of 100 mm by 30 mm and a substrate thickness between 2 mm and 3 mm. Two parallel cuts form the peel strip, which should be centered and have a smooth, straight cut.

The metallic coating thickness should be greater than 20 µm for handling strength. If the coating is thinner, the document allows reinforcement by additional copper plating or other supporting methods, but lead foil tape is not recommended. Thickness is measured with methods from ISO 3882 or ISO 14571, and the measured thickness is part of the designation.

Conditioning and test procedure

ISO 25245:2026 requires specimen conditioning before testing: either heat treatment at 80 °C for at least 1 h or room conditioning for at least 48 h. Before peeling, the specimen is stabilized at the test temperature in the thermostatic chamber for at least 15 min.

The peel strip is pulled vertically at a constant speed of 25 mm/min, with an allowed tolerance of 3 mm/min. This fixed speed is important because the force response depends on how fast the coating is separated from the plastic.

Temperature control

ISO 25245:2026 defines test temperatures from below -100 °C up to 250 °C, plus room temperature. The chamber temperature shall be held within ±2 °C. If no chamber is used, the document points to 23 °C and 50 % relative humidity as the recommended ambient condition, following ISO 527-1.

This matters because the standard is meant for coatings used over wide service temperatures, including cold and hot conditions that can change adhesion.

Data analysis and result expression

ISO 25245:2026 requires force data collection at 2 Hz or higher. The result is the arithmetic mean peel force in the effective region, expressed in kN/m. The document notes that kN/m is numerically the same as N/mm, but it uses kN/m for consistency.

In practice, the user must keep the raw force-displacement curve and calculate the mean from the valid part of the peel.

Designation of the coating system

ISO 25245:2026 builds the designation from the test method, temperature, substrate, coating metal and process, coating thickness, mean peel strength and number of specimens. For multilayer coatings, the coating layers are listed from bottom to top.

The temperature code uses At plus a temperature letter or value, and RT means room temperature without chamber control. The substrate code uses PL for plastics, with the plastic name taken from ISO 472. The coating process code uses letters such as VE, SP, EL, EP and OP.

Test report content

ISO 25245:2026 requires the test report to include the standard reference, test date and location, specimen identification and designation, specimen preparation method, equipment details, test conditions, measurement data, operator identification and any deviations with justification.

That gives the reader enough information to trace the result back to the specimen, the chamber conditions and the test machine.

What terms does ISO 25245:2026 define?

ISO 25245:2026 uses a small set of designation terms that matter in daily use.

• Peel strength - the arithmetic mean peel force in the effective region, reported in kN/m.
• Ap - the designation prefix showing that adhesion strength was determined by the peel test method.
• At - the prefix that identifies the test temperature of the thermostatic chamber.
• PL - the substrate code used for plastics; the plastic abbreviation itself is taken from ISO 472.
• RT - room temperature, used when the test is run without a thermostatic chamber.
• EL - electroless plating, a coating process code used in the designation.
• EP - electroplating, the coating process code for electrically deposited metallic coatings.
• Designation - the full code that combines method, temperature, substrate, coating structure, thickness, peel strength and specimen count.

Who uses ISO 25245:2026?

ISO 25245:2026 is used by organizations that make, test or buy metal-coated plastic parts. The introduction points to automotive and transport, electronics and electrical equipment, consumer goods and appliances, telecommunications and information technology, industrial equipment and machinery, medical devices and instrumentation, aerospace, and renewable energy.

In practice, the standard is useful for process development, quality assurance, incoming inspection and product verification. It helps when a team needs to compare adhesion across coating systems, seed layers, coating thicknesses or test temperatures.

Which standards are used with ISO 25245:2026?

ISO 25245:2026 refers to several standards that support its terminology, sampling, thickness measurement and test conditions.

• ISO 472 - supplies plastics vocabulary and the plastic material abbreviations used in the designation.
• ISO 2080 - supplies coating vocabulary, including coating-process terms.
• ISO 3882 - provides methods for measuring coating thickness.
• ISO 4519 - provides sampling procedures when statistically correct sampling is required.
• ISO 14571 - provides a micro-resistivity method for coating thickness measurement on non-metallic basis materials.
• ISO 17450-1 - supports the geometrical product specification concepts used for specimen and cut quality.
• ISO 527-1 - is referenced for recommended ambient temperature and humidity when no chamber is used.
• ISO 7500-1 - is cited in a note on the consistency of kN/m reporting with force-testing practice.

What does the ISO 25245:2026 document contain?

ISO 25245:2026 contains a complete peel-test procedure, from specimen preparation to result reporting. The figures show the specimen holder arrangements, the thermostatic chamber setup, specimen geometry, the thickness-measurement location and an example peel force-displacement curve.

The tables give the temperature designations, substrate material codes and coating process codes. The annexes add practical examples for chamber design, inter-laboratory testing and the effect of temperature on peel strength. The document is therefore not just a short test outline - it also gives the coding system and reporting structure needed to describe metallic coatings on plastics in a consistent way.

International
Standard
ISO 25245
First edition
Peel strength of metallic coatings
2026-09
on plastics — Designation and
test method under controlled
temperatures
Résistance au pelage des revêtements métalliques sur les
plastiques — Désignation et méthode d'essai sous températures
régulées
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
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or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test method . 1
4.1 General .1
4.2 Apparatus .2
4.3 Specimen .3
4.3.1 Sampling .3
4.3.2 Size and peel-strip preparation .4
4.3.3 Metallic coatings and their thickness measurement .4
4.4 Procedures .6
4.4.1 General .6
4.4.2 Conditioning of specimen .6
4.4.3 Peel test .6
4.4.4 Surrounding temperature of specimen .6
4.5 Data analysis .8
5 Designation . 9
5.1 General .9
5.2 Test temperature .10
5.3 Substrate materials .10
5.4 Metallic coatings .11
6 Test report .11
6.1 Minimum information to be included in the test report .11
6.2 Example of designation . 12
Annex A (informative) Thermostatic chamber . 14
Annex B (informative) Examples of adhesion strength measurement of metallic coatings using
peel tests — Round robin test .15
Annex C (informative) Examples of adhesion strength measurement of metallic coatings using
peel test — Effects of test temperature .23
Bibliography .26

iii
Foreword
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The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
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This document was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings.
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.

iv
Introduction
Metallic coatings on plastic substrates are widely used across many industries.
This document describes a quantitative peel test method and associated test apparatus for evaluating the
adhesion of metallic coatings to plastics under controlled temperatures. The method is intended for use
across a broad range of sectors where metal-coated plastics are employed, including, but not limited to:
— automotive and transport (electrical connectors, decorative and functional coatings);
— electronics and electrical equipment (semiconductor chip packages, printed wiring boards, components,
housings, electromagnetic interference shielding);
— consumer goods and appliances (decorative plating, functional metallization);
— telecommunications and information technology (connector housings, shielding components);
— industrial equipment and machinery (protective and functional coatings on plastic parts);
— medical devices and instrumentation (metalized surfaces on plastic components where adhesion is
critical);
— aerospace (functional and protective metal coatings on polymer components);
— renewable energy (components for solar, wind and related systems where metallized plastics are used).
The examples given in the annexes illustrate the method applied to a variety of coating systems and
specimen types and are informative only; they do not limit the scope of application of this method.
Monitoring of the adhesion performance of these coatings is essential for product reliability and quality
assurance. Conventional methods for evaluating adhesion, such as thermal cycle testing (as specified in
ISO 4525 and JIS H 8630), cross-cut tests and tape peel tests, are commonly used. However, these methods
generally yield qualitative or semi-quantitative results and do not provide direct numerical values of bond
strength.
In contrast, peel testing provides quantitative and reproducible data directly related to the interfacial bond
strength. It is specified in several national and industry standards, such as JIS H 8630, ASTM B533, and
IPC–TM–650 Method 2.4.8, and is widely applied for characterizing adhesion of metallic coatings on plastic
substrates and copper-clad laminates.
Of particular importance is the application of peel testing to multilayer metallic coatings (e.g. Cu/Ni/
Cr), where the adhesion of the upper layers is influenced by the condition of the underlying copper layer.
Peel testing is thus essential not only for process development (e.g. surface roughening or pretreatment
optimization), but also for evaluating the mechanical integrity of the full coating system.
Although thermal cycle tests remain suitable for evaluating environmental durability and detecting defects
such as blistering, they serve a different purpose from peel tests. The two test methods are complementary
and may be used together depending on the evaluation objective.
However, existing standards define peel test procedures only at room temperature, despite the fact that
coated plastic components are often used in wide temperature ranges, including conditions below 0 °C and
above 100 °C, particularly in automotive and electronics applications.
Therefore, there is a need for a standardized method for conducting peel tests under controlled temperature
conditions, to enable consistent and reliable evaluation of adhesion strength across relevant temperature
ranges.
This document specifies a quantitative peel test method for evaluating the adhesion of metallic coatings on
plastic substrates under defined temperature conditions. It contributes to the global harmonization of test
methods for metallic coatings on plastics.

v
International Standard ISO 25245:2026(en)
Peel strength of metallic coatings on plastics — Designation
and test method under controlled temperatures
1 Scope
This document specifies the method of the peel test using a tensile testing machine to evaluate the
adhesion strength of metallic coatings on plastic substrates under controlled temperatures. It also specifies
the designations of the peel test results. The designation consists of the adhesion of metallic coatings
to the substrate and test temperature, as well as the substrate material and the principal component,
manufacturing process and thickness of the metallic coatings.
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.
ISO 472, Plastics — Vocabulary
ISO 2080, Metallic and other inorganic coatings — Surface treatment, metallic and other inorganic coatings —
Vocabulary
ISO 3882, Metallic and other inorganic coatings — Review of methods of measurement of thickness
ISO 4519, Electrodeposited metallic coatings and related finishes — Sampling procedures for inspection by
attributes
ISO 14571, Metallic coatings on non-metallic basis materials — Measurement of coating thickness — Micro-
resistivity method
ISO 17450-1, Geometrical product specifications (GPS) — General concepts — Part 1: Model for geometrical
specification and verification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472, ISO 2080 and ISO 17450-1
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/
4 Test method
4.1 General
The adhesion of electroplated metallic coatings on plastic substrates is evaluated by a peel test. The test
specimen consists of a plastic substrate with metallic coatings. The coatings are peeled vertically from the
substrate under controlled temperature conditions using a tensile testing machine. The required peeling
force is recorded. The procedure for the peel test is described in Reference [1] and Reference [2].

4.2 Apparatus
4.2.1 Tensile testing machine, which shall be used to continuously record the peel force. The
recommended accuracy classes of the force sensors are specified in Reference [1].
4.2.2 Specimen holder, equipped with a device to maintain the peeling direction at 90 ° during the test
shall be used. Figure 1 shows an example of a specimen holder with rollers to maintain the 90 ° peeling
angle. Figure 2 shows an example of a specimen holder with pulleys and a wire to achieve the same.
Key
1 chuck
2 coating of specimen
3 substrate of specimen
4 specimen holder
5 roller
Figure 1 — Example of a specimen holder with rollers

Key
1 chuck
2 coating of specimen
3 substrate of specimen
4 sliding table
5 pulley
6 wire
Figure 2 — Example of a specimen holder with pulley, wire and sliding table
4.2.3 Thermostatic chamber, integrated with the tensile testing machine shall be used for tests
conducted under controlled temperature conditions. See Annex A for a descriptive example of a thermostatic
chamber.
4.3 Specimen
4.3.1 Sampling
Specimens shall be cut from the flat portions of the products.
Following the standards for statistically correct sampling can lead to large sample sizes, which are usually
not tested in daily laboratory routine for economic reasons. For routine testing, users should consider
pragmatic sampling plans. Where statistically correct sampling is required, users shall follow the methods
given in ISO 4519.
When specimens are prepared as an alternative to cutting directly from the product (e.g. when a sufficiently
wide flat region cannot be obtained), the test report should include:
a) a description of the specimen preparation method, including substrate and coating materials used and
full details of the coating procedures;

b) justification for the use of prepared specimens rather than specimens taken directly from the product
(e.g. absence of suitable flat area, safety or processing constraints);
c) any known differences between the prepared specimens and the product (e.g. dimensional differences,
cure conditions, surface finish) and an assessment of their potential impact on the test results;
d) any limitations on the interpretation of results arising from the use of prepared specimens.
4.3.2 Size and peel-strip preparation
Specimens with dimensions of 100 ± 2 mm × 30 ± 2 mm and a substrate thickness between 2 mm and 3 mm,
as shown in Figure 3, are recommended.
Specimens with larger surface areas, such as those described in Reference [2], can also be used. If the
substrate thickness exceeds the recommended range, sufficient time shall be allowed for temperature
uniformity within the substrate.
Two parallel cuts shall be made to form one peel strip. The metallic coating shall be cut through to the
substrate. The width of the peel strip shall be between 10 mm and 25 mm; the recommended width is
10 ± 0,1 mm.
The cut slits shall have straight and smooth surfaces. The parallelism not exceeding 0,1 mm (the method
can be carried out according to ISO 17450-1). The peel strip shall be located at the central portion of the
specimen.
The peel strip shall be initially lifted by approximately 5 mm from the specimen edge. A tab of approximately
30 mm in length shall be formed for attachment to the testing machine.
Dimensions in millimetres
Key
A start point of peel test
B cut slit
NOTE Symbols showing the geometrical specifications are according to ISO 17450-1.
Figure 3 — Specimen size
4.3.3 Metallic coatings and their thickness measurement
The total thickness of the metallic coatings on the specimen should be greater than 20 µm to ensure
sufficient mechanical strength for specimen handling.
If the total coating thickness is 20 µm or less, additional copper electroplating should be applied to increase
the total thickness above 20 µm.

Alternatively, strength reinforcement can be provided by using fibreglass-reinforced adhesive tape,
solder coating or lead foil tape, instead of additional copper plating (see Reference [2], Reference [4] and
Reference [5]).
The use of lead foil tape is not recommended because of health, safety and regulatory considerations.
In the case of multilayer coatings (e.g. Cu/Ni/Cr), the peel test can be performed either on intermediate
coatings (e.g. copper alone) or on the entire multilayer structure, depending on the objective of the
evaluation.
If the primary purpose is process development (e.g. optimization of surface roughening or chemical
pretreatment), copper-only samples are recommended.
However, if the goal is to assess the adhesion performance of the final product, the test should be carried out
on the finished multilayer structure, as the adhesion of upper layers (e.g. Ni and Cr) is strongly influenced by
the underlying copper layer and overall interface integrity.
Peel strength testing and thermal cycle testing serve different purposes and evaluate different physical
aspects of adhesion. While thermal cycle tests are suitable for assessing environmental durability (e.g.
blistering), peel tests provide quantitative values for interfacial adhesion strength and enable statistical
quality control.
The coating thickness of the specimens shall be measured using the methods specified in ISO 3882 or
ISO 14571.
The measured thickness of the coatings shall be indicated in the designation (see 5.4).
Measurements should be taken at three or more points in the peel strip test area, as shown in Figure 4.
The arithmetic mean of the measured values shall be used as the representative thickness in the designation.
If measurement at three points is not feasible, a single measurement shall be taken at a point 50 mm from
the end of the specimen.
Dimensions in millimetres
Key
A region to be discarded
B test area (40 mm or longer)
C tab to attach the testing machine
D effective data area
E pulled-off start point
Figure 4 — Location of coating thickness measurement

4.4 Procedures
4.4.1 General
Peel strength testing and thermal cycle testing serve different purposes and evaluate different physical
aspects of adhesion. While thermal cycle tests are suitable for assessing environmental durability (e.g.
blistering), peel tests provide quantitative values for interfacial adhesion strength and enable statistical
quality control.
4.4.2 Conditioning of specimen
Specimens shall be heat-treated at 80 °C for at least 1 h or conditioned at room temperature for at least 48 h
prior to the peel test.
NOTE Peel strength of unconditioned specimens can change over time (see Reference [1] and Reference [2]).
4.4.3 Peel test
The peel test shall be conducted in the following sequence:
a) The specimen shall be secured in the specimen holder. The holder shall be mounted on the testing
machine as shown in Figure 1, Figure 2 and Figure 5.
b) The specimen shall be placed in a thermostatic chamber for at least 15 min, until its surrounding
temperature is stabilized at the test temperature. If the test is conducted at room temperature, this step
may be omitted.
c) The peel strip shall be vertically separated from the substrate at a constant speed of (25 ± 3) mm/min.
The force shall be recorded continuously.
Examples of adhesion strength measurements using peel tests are given in Annex B.
4.4.4 Surrounding temperature of specimen
The surrounding temperatures to be applied to specimens are shown in Table 1 and shall be maintained
within ±2 °C using a thermostatic chamber.
If a thermostatic chamber is not used, the recommended ambient temperature and relative humidity are
23 ± 2 °C and 50 ± 10 %, respectively, as specified in ISO 527-1.
Unless the specimen material is sensitive to humidity, humidity control is not essential.
Examples of adhesion strength measurements using peel tests at controlled temperatures are given in
Annex C.
a) Image of specimen holder and tensile testing machine

b) Diagram of specimen holder and tensile testing machine
Key
1 tensile testing machine
2 thermostatic chamber
3 specimen equipped in specimen holder
Figure 5 — Specimen mounted in a specimen holder installed in a tensile testing machine with a
thermostatic chamber
4.5 Data analysis
Figure 6 shows an example of raw data obtained from a peel test, i.e. a peel force–displacement curve.
Data should be collected at a sampling frequency of 2 Hz or higher.
The arithmetic mean of the peel force within the effective region shall be determined and expressed in
kilonewtons per metre (kN/m) as the test result.
NOTE Numerical values expressed in kN/m are identical to those expressed in N/mm, which is also commonly
used in industry. The use of kN/m is consistent with ISO 7500-1 and with SI base units.

Key
A region to be discarded (10 mm)
B test area (40 mm or longer)
C tab to attach the testing machine (30 mm or shorter)
D effective data area (30 mm)
E arithmetic mean value of effective data
X displacement expressed in mm
F peel force expressed in kN/m
Figure 6 — Example of raw data from a peel test
5 Designation
5.1 General
The designation of the adhesion strength of metallic coatings shall be constructed using the following
components:
a) the letters "Ap" to indicate that the adhesion strength was determined by the peel test method, followed
by a solidus ("/");
b) the letters "At" followed by a letter indicating the test temperature in a thermostatic chamber (see 5.3),
followed by a solidus (/);
c) letters indicating the substrate material (see 5.4), followed by a solidus (/);
d) the chemical symbol of the principal metallic element of the coating, followed by lower-case letters
indicating the coating process used for the specimen (see 5.4);
e) a number indicating the coating thickness in micrometres, as determined in 4.3.3, followed by a space if
ano
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