Metallic coatings on non-metallic basis materials - Measurement of coating thickness - Micro-resistivity method (ISO 14571:2020)

This document specifies a method for non-destructive measurements of the thickness of conductive coatings on non-conductive base materials. This method is based on the principle of the sheet resistivity measurement and is applicable to any conductive coatings and layers of metal and semiconductor materials. In general, the probe has to be adjusted to the conductivity and the thickness of the respective application. However, this document focuses on metallic coatings on non-conductive base materials (e.g. copper on plastic substrates, printed circuit boards).
This method is also applicable to thickness measurements of conductive coatings on conductive base materials, if the resistivity of the coating and the base material is significantly different. However, this case is not considered in this document.

Metallische Überzüge auf nichtmetallischen Grundwerkstoffen - Schichtdickenmessung - Mikro-Widerstand-Verfahren (ISO 14571:2020)

Dieses Dokument legt ein Verfahren für zerstörungsfreie Messungen der Dicke von elektrisch leitenden Überzügen auf nichtleitenden Grundwerkstoffen fest. Dieses Verfahren beruht auf dem Prinzip der Flächenwiderstandsmessung und ist auf alle leitfähigen Überzügen und Schichten aus metallischen und halbleitenden Materialien anwendbar. Generell muss die Sonde an die Leitfähigkeit und die Schichtdicke des jeweiligen Einsatzfalls angepasst sein. Dieses Dokument befasst sich jedoch ausschließlich mit metallischen Überzügen auf nichtleitenden Grundwerkstoffen (z. B. Kupfer auf Kunststoffsubstraten, Leiterplatten).
Dieses Verfahren ist ebenfalls für die Schichtdickenmessung von leitfähigen Überzügen auf leitfähigen Grundmaterialien anwendbar, wenn sich der spezifische Widerstand vom Grundmaterial von dem des Überzuges unterscheidet. Dieser Fall wird in diesem Dokument nicht berücksichtigt.

Revêtements métalliques sur matériaux non-métalliques - Mesurage de l'épaisseur des revêtements - Méthode utilisant la micro-résistivité (ISO 14571:2020)

Le présent document spécifie une méthode de mesurages non destructifs de l’épaisseur des revêtements conducteurs sur des matériaux de base non conducteurs. Cette méthode repose sur le principe du mesurage de la résistivité d’une plaque et elle est applicable à tous les revêtements conducteurs et couches de métaux et de matériaux semi-conducteurs. En général, le palpeur doit être ajusté à la conductivité et à l’épaisseur de l’application correspondante. Toutefois, le présent document est centré sur les revêtements métalliques appliqués sur des matériaux de base non conducteurs (par exemple, cuivre sur substrats en plastique, cartes de circuits imprimés).
Cette méthode est aussi applicable aux mesurages d’épaisseur des revêtements conducteurs sur des matériaux de base conducteurs, si la résistivité du revêtement et celle du matériau de base sont nettement différentes. Cependant, ce cas n’est pas traité dans le présent document.

Kovinske prevleke na materialih z nekovinsko osnovo - Merjenje debeline prevleke - Metoda mikroupornosti (ISO 14571:2020)

General Information

Status
Published
Publication Date
08-Nov-2022
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
06-Nov-2023
Completion Date
09-Nov-2022

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SLOVENSKI STANDARD
SIST EN ISO 14571:2023
01-januar-2023
Nadomešča:
SIST EN 14571:2005
Kovinske prevleke na materialih z nekovinsko osnovo - Merjenje debeline prevleke
- Metoda mikroupornosti (ISO 14571:2020)

Metallic coatings on non-metallic basis materials - Measurement of coating thickness -

Micro-resistivity method (ISO 14571:2020)

Metallische Überzüge auf nichtmetallischen Grundwerkstoffen - Schichtdickenmessung -

Mikro-Widerstand-Verfahren (ISO 14571:2020)

Revêtements métalliques sur matériaux non-métalliques - Mesurage de l'épaisseur des

revêtements - Méthode utilisant la micro-résistivité (ISO 14571:2020)
Ta slovenski standard je istoveten z: EN ISO 14571:2022
ICS:
17.040.20 Lastnosti površin Properties of surfaces
25.220.40 Kovinske prevleke Metallic coatings
SIST EN ISO 14571:2023 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 14571:2023
---------------------- Page: 2 ----------------------
SIST EN ISO 14571:2023
EN ISO 14571
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2022
EUROPÄISCHE NORM
ICS 25.220.40 Supersedes EN 14571:2005
English Version
Metallic coatings on non-metallic basis materials -
Measurement of coating thickness - Micro-resistivity
method (ISO 14571:2020)

Revêtements métalliques sur matériaux non- Metallische Überzüge auf nichtmetallischen

métalliques - Mesurage de l'épaisseur des revêtements Grundwerkstoffen - Schichtdickenmessung - Mikro-

- Méthode utilisant la micro-résistivité (ISO Widerstand-Verfahren (ISO 14571:2020)

14571:2020)
This European Standard was approved by CEN on 30 October 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14571:2022 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 14571:2023
EN ISO 14571:2022 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

---------------------- Page: 4 ----------------------
SIST EN ISO 14571:2023
EN ISO 14571:2022 (E)
European foreword

The text of ISO 14571:2020 has been prepared by Technical Committee ISO/TC 107 "Metallic and other

inorganic coatings” of the International Organization for Standardization (ISO) and has been taken over

as EN ISO 14571:2022 by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings,

including for corrosion protection and corrosion testing of metals and alloys” the secretariat of which is

held by BSI.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by May 2023, and conflicting national standards shall be

withdrawn at the latest by May 2023.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 14571:2005.

Any feedback and questions on this document should be directed to the users’ national standards body.

A complete listing of these bodies can be found on the CEN website.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the

United Kingdom.
Endorsement notice

The text of ISO 14571:2020 has been approved by CEN as EN ISO 14571:2022 without any modification.

---------------------- Page: 5 ----------------------
SIST EN ISO 14571:2023
---------------------- Page: 6 ----------------------
SIST EN ISO 14571:2023
INTERNATIONAL ISO
STANDARD 14571
First edition
2020-11
Metallic coatings on non-metallic basis
materials — Measurement of coating
thickness — Micro-resistivity method
Revêtements métalliques sur matériaux non-métalliques — Mesurage
de l'épaisseur des revêtements — Méthode utilisant la micro-
résistivité
Reference number
ISO 14571:2020(E)
ISO 2020
---------------------- Page: 7 ----------------------
SIST EN ISO 14571:2023
ISO 14571:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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 the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 14571:2023
ISO 14571:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Measurement principle ................................................................................................................................................................................. 1

5 Factors affecting measurement uncertainty ........................................................................................................................... 4

5.1 Range of measurement .................................................................................................................................................................... 4

5.2 Coating resistivity ................................................................................................................................................................................. 4

5.3 Width of the sample............................................................................................................................................................................ 4

5.4 Curvature ..................................................................................................................................................................................................... 5

5.5 Surface roughness ................................................................................................................................................................................ 5

5.6 Temperature .............................................................................................................................................................................................. 5

5.7 Probe contact pressure .................................................................................................................................................................... 5

6 Calibration of instruments ......................................................................................................................................................................... 5

6.1 General ........................................................................................................................................................................................................... 5

6.2 Calibration standards ........................................................................................................................................................................ 6

6.3 Verification ................................................................................................................................................................................................. 6

7 Procedure..................................................................................................................................................................................................................... 6

7.1 General ........................................................................................................................................................................................................... 6

7.2 Width of the sample............................................................................................................................................................................ 6

7.3 Curvature ..................................................................................................................................................................................................... 6

7.4 Number of measurements ............................................................................................................................................................ 6

7.5 Surface cleanliness .............................................................................................................................................................................. 7

8 Accuracy requirements.................................................................................................................................................................................. 7

9 Test report ................................................................................................................................................................................................................... 7

Annex A (informative) Method for determining the critical current path width ...................................................8

Bibliography ................................................................................................................................................................................................................................ 9

© ISO 2020 – All rights reserved iii
---------------------- Page: 9 ----------------------
SIST EN ISO 14571:2023
ISO 14571:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

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 documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings,

in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/

TC 262, Metallic and other inorganic coatings, including for corrosion protection and corrosion testing of

metals and alloys, in accordance with the Agreement on technical cooperation between ISO and CEN

(Vienna Agreement).

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 © ISO 2020 – All rights reserved
---------------------- Page: 10 ----------------------
SIST EN ISO 14571:2023
INTERNATIONAL STANDARD ISO 14571:2020(E)
Metallic coatings on non-metallic basis materials —
Measurement of coating thickness — Micro-resistivity
method
1 Scope

This document specifies a method for non-destructive measurements of the thickness of conductive

coatings on non-conductive base materials. This method is based on the principle of the sheet resistivity

measurement and is applicable to any conductive coatings and layers of metal and semiconductor

materials. In general, the probe has to be adjusted to the conductivity and the thickness of the respective

application. However, this document focuses on metallic coatings on non-conductive base materials

(e.g. copper on plastic substrates, printed circuit boards).

This method is also applicable to thickness measurements of conductive coatings on conductive base

materials, if the resistivity of the coating and the base material is significantly different. However, this

case is not considered in this document.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Measurement principle

The sheet resistivity method uses the so-called “four-point probe” as shown in Figure 1. A row of

four spring-loaded metal tips are placed in contact with the surface of the conductive coating. The tip

distances between the outer and inner tips, S and S , are equal. Usually, a constant current is passed

1 3

through the two outer contacts (labelled as 1). The introduced current penetrates the conductive

material of the coating with the resistivity ρ. The resulting voltage drop is measured across the two

inner contacts (labelled as 2).

In general, the flow of the introduced current is non-uniformly distributed over the cross-section of the

coating and is not parallel to the coating (see Figure 2). The current density decreases with increasing

distance from the direct line between the outer contacts labelled as 1 (with depth and width). If the

current is effectively limited by the thickness of the coating, the voltage drop between the inner

contacts labelled as 2 is a measure of the thickness.
© ISO 2020 – All rights reserved 1
---------------------- Page: 11 ----------------------
SIST EN ISO 14571:2023
ISO 14571:2020(E)
Key
1 outer contacts of the probe
2 inner contacts of the probe
3 conductive coating
4 non-conductive base material
t coating thickness
Figure 1 — Schematic re
...

SLOVENSKI STANDARD
oSIST prEN ISO 14571:2022
01-september-2022
Kovinske prevleke na materialih z nekovinsko osnovo - Merjenje debeline prevleke
- Metoda mikroupornosti (ISO 14571:2020)

Metallic coatings on non-metallic basis materials - Measurement of coating thickness -

Micro-resistivity method (ISO 14571:2020)

Metallische Überzüge auf nichtmetallischen Grundwerkstoffen - Schichtdickenmessung -

Mikro-Widerstand-Verfahren (ISO 14571:2020)

Revêtements métalliques sur matériaux non-métalliques - Mesurage de l'épaisseur des

revêtements - Méthode utilisant la micro-résistivité (ISO 14571:2020)
Ta slovenski standard je istoveten z: prEN ISO 14571
ICS:
17.040.20 Lastnosti površin Properties of surfaces
25.220.40 Kovinske prevleke Metallic coatings
oSIST prEN ISO 14571:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 14571:2022
---------------------- Page: 2 ----------------------
oSIST prEN ISO 14571:2022
INTERNATIONAL ISO
STANDARD 14571
First edition
2020-11
Metallic coatings on non-metallic basis
materials — Measurement of coating
thickness — Micro-resistivity method
Revêtements métalliques sur matériaux non-métalliques — Mesurage
de l'épaisseur des revêtements — Méthode utilisant la micro-
résistivité
Reference number
ISO 14571:2020(E)
ISO 2020
---------------------- Page: 3 ----------------------
oSIST prEN ISO 14571:2022
ISO 14571:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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 the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 14571:2022
ISO 14571:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Measurement principle ................................................................................................................................................................................. 1

5 Factors affecting measurement uncertainty ........................................................................................................................... 4

5.1 Range of measurement .................................................................................................................................................................... 4

5.2 Coating resistivity ................................................................................................................................................................................. 4

5.3 Width of the sample............................................................................................................................................................................ 4

5.4 Curvature ..................................................................................................................................................................................................... 5

5.5 Surface roughness ................................................................................................................................................................................ 5

5.6 Temperature .............................................................................................................................................................................................. 5

5.7 Probe contact pressure .................................................................................................................................................................... 5

6 Calibration of instruments ......................................................................................................................................................................... 5

6.1 General ........................................................................................................................................................................................................... 5

6.2 Calibration standards ........................................................................................................................................................................ 6

6.3 Verification ................................................................................................................................................................................................. 6

7 Procedure..................................................................................................................................................................................................................... 6

7.1 General ........................................................................................................................................................................................................... 6

7.2 Width of the sample............................................................................................................................................................................ 6

7.3 Curvature ..................................................................................................................................................................................................... 6

7.4 Number of measurements ............................................................................................................................................................ 6

7.5 Surface cleanliness .............................................................................................................................................................................. 7

8 Accuracy requirements.................................................................................................................................................................................. 7

9 Test report ................................................................................................................................................................................................................... 7

Annex A (informative) Method for determining the critical current path width ...................................................8

Bibliography ................................................................................................................................................................................................................................ 9

© ISO 2020 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST prEN ISO 14571:2022
ISO 14571:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

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 documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings,

in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/

TC 262, Metallic and other inorganic coatings, including for corrosion protection and corrosion testing of

metals and alloys, in accordance with the Agreement on technical cooperation between ISO and CEN

(Vienna Agreement).

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 © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST prEN ISO 14571:2022
INTERNATIONAL STANDARD ISO 14571:2020(E)
Metallic coatings on non-metallic basis materials —
Measurement of coating thickness — Micro-resistivity
method
1 Scope

This document specifies a method for non-destructive measurements of the thickness of conductive

coatings on non-conductive base materials. This method is based on the principle of the sheet resistivity

measurement and is applicable to any conductive coatings and layers of metal and semiconductor

materials. In general, the probe has to be adjusted to the conductivity and the thickness of the respective

application. However, this document focuses on metallic coatings on non-conductive base materials

(e.g. copper on plastic substrates, printed circuit boards).

This method is also applicable to thickness measurements of conductive coatings on conductive base

materials, if the resistivity of the coating and the base material is significantly different. However, this

case is not considered in this document.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Measurement principle

The sheet resistivity method uses the so-called “four-point probe” as shown in Figure 1. A row of

four spring-loaded metal tips are placed in contact with the surface of the conductive coating. The tip

distances between the outer and inner tips, S and S , are equal. Usually, a constant current is passed

1 3

through the two outer contacts (labelled as 1). The introduced current penetrates the conductive

material of the coating with the resistivity ρ. The resulting voltage drop is measured across the two

inner contacts (labelled as 2).

In general, the flow of the introduced current is non-uniformly distributed over the cross-section of the

coating and is not parallel to the coating (see Figure 2). The current density decreases with increasing

distance from the direct line between the outer contacts labelled as 1 (with depth and width). If the

current is effectively limited by the thickness of the coating, the voltage drop between the inner

contacts labelled as 2 is a measure of the thickness.
© ISO 2020 – All rights reserved 1
---------------------- Page: 7 ----------------------
oSIST prEN ISO 14571:2022
ISO 14571:2020(E)
Key
1 outer contacts of the probe
2 inner contacts of the probe
3 conductive coating
4 non-conductive base material
t coating thickness
Figure 1 — Schematic representation of the sheet resistivity method
2 © ISO 2020 – All rights reserved
---------------------- Page: 8 ----------------------
oSIST prEN ISO 14571:2022
ISO 14571:2020(E)
Key
1 outer contacts of the probe
2 inner contacts of the probe
3 conductive coating
4 non-conductive base material
t coating thickness

Figure 2 — Schematic representation of the non-uniformly distributed current within the coating

The measured voltage drop depends on the resistivity of the metallic coating, on the probe geometry

(distance of the four probe contacts S , S , S ), the applied current and the thickness of the coating. If

1 2 3

the resistivity of the coating can be expected to be homogenous and the thickness is sufficiently small,

the measured voltage drop is determined only by the unknown thickness and the applied current.

In general, there is no simple and practical equation to calculate the thickness as a function of the

material resistivity, the probe geometry and the measured voltage and current. However, there are

some well-known approximations for practical use in certain cases. Particularly in the case of equal tip

distances (S = S = S = S) and for a thickness to probe spacing ratio t/S < 0,5, the coating thickness, t, in

1 2 3
micrometres, can be calculated using Formula (1), when t/S < 0,5:
ln 2
I ()
t=ρ (1)
V π
where
ρ is the resistivity of the coating, in μΩ⋅m;
V is the potential difference across the inner probe tips, in volts;
I is the current passed through the outer probe tips, in amperes;
S is the equal probe tip spacing (S = S = S = S ).
1 2 3
© ISO 2020 – All rights reserved 3
---------------------- Page: 9 ----------------------
oSIST prEN ISO 14571:2022
ISO 14571:2020(E)

Usually the supplied current I is held constant. Therefore, the coating thickness is inversely proportional

to the measured voltage:
t= (2)
where C is a constant 0,221 ρI.

Formula (2) is the basis for many applications in the above case. In general, suitable correction functions

for Formula (2) are necessary if the prerequisite of a ratio t/S < 0,5 or an equal probe tip spacing is not

satisfied.
Because the introduced current decreases with increas
...

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