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BS EN IEC 62812:2019:2020 Edition

BS EN IEC 62812:2019:2020 Edition

$198.66

Low resistance measurements. Methods and guidance

Published By Publication Date Number of Pages
BSI 2020 52
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Resistance measurements are typically compromised by a variety of phenomena, for example serial resistance in the measurement path, self-heating or non-ohmic properties. Whether the effect of such phenomena on a resistance measurement is acceptable or not depends on the magnitude of each effect in comparison to the resistance and to the required accuracy. Hence, the risk of erroneous resistance measurements increases with decreasing resistance and with a tightening of the permissible tolerance.

This document specifies methods of measurement and associated test conditions that eliminate or reduce the influence of adverse phenomena in order to improve the attainable accuracy of low-resistance measurements.

The methods described in this document are applicable for the individual measurements of the resistance of individual resistors, and also for resistance measurements as part of a test sequence. They are applied if prescribed by a relevant component specification, or if agreed between a customer and a manufacturer.

PDF Catalog

PDF Pages PDF Title
2 undefined
5 Annex ZA(normative)Normative references to international publicationswith their corresponding European publications
8 English
CONTENTS
10 FOREWORD
12 1 Scope
2 Normative references
3 Terms and definitions
13 4 Resistance measurement phenomena
4.1 General
4.2 Lead and contact resistance
14 Figures
Figure 1 ā€“ Resistance measurement using two-wire sensing
15 4.3 Self-heating
16 4.4 Variation of resistance with temperature
Figure 2 ā€“ Variation of resistance with temperature (random example)
17 Figure 3 ā€“ Resistances on a resistor with lead wires
18 4.5 Thermoelectric e.m.f.
Figure 4 ā€“ SMD chip resistor on a PCB
19 Figure 5 ā€“ Thermoelectric e.m.f.
Tables
Table 1 ā€“ Relative Seebeck coefficients of selected metals
20 Figure 6 ā€“ Thermocouples on a resistor with lead wires
21 4.6 Peltier effect
Figure 7 ā€“ Resistance measurement affected by thermoelectric e.m.f.
22 5 Methods of measurement
5.1 General
5.2 Four-wire resistance measurement
23 Figure 8 ā€“ Four-wire resistance measurement
25 5.3 Offset compensation method
Figure 9 ā€“ Offset compensation method for resistance measurement
26 Figure 10 ā€“ Current and voltage in the offset compensation method
28 5.4 Current inversion method
Figure 11 ā€“ Current inversion method for resistance measurement
29 Figure 12 ā€“ Current and voltage in the current inversion method
31 5.5 Differential current inversion method
32 Figure 13 ā€“ Current and voltage in the differential current inversion method
34 5.6 Short-term trigger method
37 Figure 14 ā€“ Example of resistor specimen
38 6 Connecting the specimen
6.1 Resistors with lead wires for soldered assembly
6.1.1 Connecting leaded resistors in a test fixture
Figure 15 ā€“ Connecting leaded resistors in a test fixture
39 6.2 Resistors with solder terminations for surface mount assembly
6.2.1 Connecting SMD resistors on a test substrate
Figure 16 ā€“ Resistance of cylindrical copper lead wires
40 Figure 17 ā€“ Soldering pad of test substrate for Kelvin (four-point) connections
41 6.2.2 Connecting SMD resistors in a test fixture
Figure 18 ā€“ Resistance of PCB conductor tracks with 35 Āµm copper thickness
42 7 Information to be given in the relevant component specification
Figure 19 ā€“ Example for connecting SMD resistors on a test fixture
43 Annex A (normative) Letter symbols and abbreviated terms
A.1 Letter symbols
Table A.1 ā€“ Letter symbols
44 A.2 Abbreviated terms
45 Annex B (informative) Test results of soldering pad with Kelvin connection for surface mount resistors
B.1 General
B.2 Test procedures
B.2.1 Test substrates
46 Figure B.1 ā€“ Lengths of soldering pad
Figure B.2 ā€“ Position of voltage sense conductor
47 B.2.2 Test method
Table B.1 ā€“ Thickness of solder printing screen
48 B.3 Measurement result and studies
Table B.2 ā€“ Table of test conditions
49 Figure B.3 ā€“ Thickness of the solder printing screen and position of sense line
Figure B.4 ā€“ Position of voltage-sensing line
50 Figure B.5 ā€“ Soldering pad length
Figure B.6 ā€“ Recommended soldering pad
51 Bibliography

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BS EN IEC 62812:2019
$198.66