ISO 25245:2026

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
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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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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
...