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BS EN IEC 60738-1:2022:2023 Edition

BS EN IEC 60738-1:2022:2023 Edition

$215.11

Thermistors. Directly heated positive temperature coefficient – Generic specification

Published By Publication Date Number of Pages
BSI 2023 72
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This part of IEC 60738 describes terms and methods of test for positive step-function temperature coefficient thermistors, insulated and non-insulated types typically made from ferro-electric semi-conductor materials. It establishes standard terms, inspection procedures and methods of test for use in detail specifications for Qualification Approval and for Quality Assessment Systems for electronic components.

PDF Catalog

PDF Pages PDF Title
2 undefined
5 Annex ZA (normative)Normative references to international publicationswith their corresponding European publications
7 English
CONTENTS
12 FOREWORD
14 1 Scope
2 Normative references
15 3 Terms and definitions
17 Figures
Figure 1 – Typical resistance-temperature characteristicand definitions for PTC thermistors (at zero power)
18 Figure 2 – Typical R-TNF characteristic for PTC thermistors in sensor applications
19 Figure 3 – Typical current/voltage characteristic for PTC thermistors
22 Figure 4 – Iin against t at Udc
Figure 5 – Iin against t at URMS
24 4 General requirements
4.1 Units and symbols
25 4.2 Preferred values
4.2.1 Climatic categories
4.2.2 Spacings
4.3 Marking
4.3.1 General
Tables
Table 1 – Creepage distances and clearances
26 4.3.2 Coding
5 General provisions for measurements and test method
5.1 General
5.2 Standard conditions for testing
5.2.1 Standard atmospheric conditions for testing
5.2.2 Error of measurement
5.3 Drying and recovery
5.3.1 Drying
27 5.3.2 Recovery
5.3.3 Shock test severities
5.3.4 Vibration severities
5.4 Mounting (for surface mount thermistors only)
5.4.1 General
Table 2 – Test severities of vibration
28 5.4.2 Printed wiring board and land pattern
5.4.3 Wave soldering method
5.4.4 Reflow soldering method
29 6 Electrical tests and measurements
6.1 Zero-power resistance
6.1.1 General
6.1.2 Measurement procedures
30 6.1.3 Requirements
6.2 Temperature coefficient of resistance
6.2.1 General
6.2.2 Requirements
6.3 Insulation resistance (for insulated types only)
6.3.1 General
6.3.2 Test methods
31 6.3.3 Applied voltage
6.3.4 Requirements
6.4 Voltage proof (for insulated types only)
6.4.1 General
6.4.2 Test methods
6.4.3 Test voltage
6.4.4 Requirements
6.5 Resistance/temperature characteristic
6.5.1 Test methods
32 6.5.2 Requirements
6.6 Dissipation factor at Umax (δ)
6.6.1 General
6.6.2 Preconditioning
6.6.3 Test circuit
6.6.4 Test methods
33 6.6.5 Requirements
6.7 Response time by ambient temperature change (ta)
6.7.1 General
6.7.2 Preconditioning
6.7.3 Test procedures
Figure 6 – Dissipation factor test circuit
34 6.7.4 Measurement procedures
6.7.5 Requirements
6.8 Response time by power change (tp)
6.8.1 Mounting
6.8.2 Test methods
Figure 7 – Temperature gradient
35 6.9 Thermal time constant by ambient temperature change (τa)
6.10 Thermal time constant by cooling (τc)
6.10.1 Mounting
6.10.2 Test methods
Figure 8 – Circuit for measurement of thermal time constant by cooling
37 6.10.3 Requirements
6.11 Tripping current and tripping time
6.12 Non-tripping current
6.13 Residual current
38 6.14 Surface temperature
Figure 9 – Circuit for surface temperature measurement
39 6.15 Inrush current
6.15.1 Measuring circuit
6.15.2 Measuring method
Figure 10 – Measuring circuit
40 6.16 Energy by discharge
6.16.1 Measuring circuit
6.16.2 Measuring method
Figure 11 – Measuring circuit
41 7 Mechanical test and measurements
7.1 Visual examination and check of dimensions
7.1.1 Visual examination
7.1.2 Marking
7.1.3 Dimensions (gauging)
7.1.4 Dimensions (detail)
7.2 Robustness of terminations
7.2.1 General
7.2.2 Test Ua1 – Tensile
42 7.2.3 Test Ub – Bending
7.2.4 Test Uc – Torsion
7.2.5 Visual examination
7.2.6 Final measurements and requirements
7.3 Vibration
Table 3 – Tensile force
43 7.4 Shock
7.5 Shear (adhesion) test
7.5.1 Test conditions
7.5.2 Test methods
7.5.3 Requirements
7.6 Substrate bending test
7.6.1 Mounting
44 7.6.2 Initial measurements
7.6.3 Test procedures
7.6.4 Measurements
7.6.5 Requirements
7.6.6 Final inspection and requirements
8 Environmental and climatic tests
8.1 Rapid change of temperature
8.2 Climatic sequence
8.2.1 General
8.2.2 Initial measurements
45 8.2.3 Dry heat
8.2.4 Damp heat (cyclic), first cycle
8.2.5 Cold
8.2.6 Low air pressure
8.2.7 Damp heat (cyclic), remaining cycles
8.2.8 Final measurements
Table 4 – Number of cycles per climatic category
46 8.3 Damp heat, steady state
8.4 Endurance
8.4.1 Endurance at room temperature (cycling)
47 8.4.2 Endurance at upper category temperature
48 8.4.3 Endurance at maximum operating temperature and maximum voltage
49 8.4.4 Cold environment electrical cycling
Figure 12 – Circuit for endurance at maximum operating temperatureand maximum voltage
50 8.4.5 Thermal runaway
9 Test related to component assembly
9.1 Solderability
9.1.1 General
9.1.2 Thermistors with leads
51 9.1.3 Surface mount thermistors
9.2 Resistance to soldering heat
9.2.1 General
9.2.2 Test conditions
52 9.2.3 The period of recovery
9.2.4 Requirements for except surface mount thermistors
9.2.5 Requirements for surface mount thermistors
10 Quality assessment procedures
53 Annex A (informative)Mounting for electrical measurements
A.1 Mounting for thermistors without wire terminations
A.2 Mounting for thermistors with wire terminations
Figure A.1 – Example of a preferred mounting methodfor thermistors without wire terminations
54 A.3 Mounting for surface mount thermistors
Figure A.2 – Example of a preferred mounting methodfor thermistors with wire terminations
55 Figure A.3 – Example of a preferred mounting method for surface mount thermistors
Table A.1 – Recommended land dimensions
56 Annex B (informative)Mounting for temperature measurements
Figure B.1 – Example of a preferred mounting method for temperature measurementon cylindrical heating elements
57 Annex Q (normative)Quality assessment procedures
Q.1 General
Q.2 Applicability of qualification approval
Q.3 Primary stage of manufacture
Q.4 Subcontracting
Q.5 Structurally similar components
Q.5.1 General
58 Q.5.2 For electrical tests
Q.5.3 For environmental tests
Q.5.4 For visual inspection
Q.5.5 For endurance tests
Q.6 Qualification approval procedures
Q.6.1 Eligibility for qualification approval
Q.6.2 Application for qualification approval
Q.6.3 Test procedure for qualification approval
59 Q.6.4 Qualification approval based on the fixed sample size procedure
61 Table Q.1 – Fixed sample size test schedule for qualification approval of thermistorsfor current limitation – Assessment level EZ
62 Table Q.2 – Fixed sample size test schedule for qualification approval of thermistorsfor use as heating elements – Assessment level EZ
63 Table Q.3 – Fixed sample size test schedule for qualification approval of thermistorsfor inrush current application – Assessment level EZ
64 Q.6.5 Granting of qualification approval
Q.6.6 Maintenance of qualification approval
Table Q.4 – Fixed sample size test schedule for qualification approval of thermistorsfor use as temperature sensing elements – Assessment level EZ
65 Q.6.7 Quality conformance inspection
Table Q.5 – Quality conformance inspection for lot-by-lot inspection
66 Q.7 Rework and repair
Q.7.1 Rework
Q.7.2 Repair
Q.8 Release for delivery
Q.8.1 General
Table Q.6 – Quality conformance inspection for periodic testing
67 Q.8.2 Release for delivery under qualification approval before the completion of group B tests
Q.9 Certified test records of released lots
Q.10 Delayed delivery
Q.11 Alternative test methods
Q.12 Manufacture outside the geographical limits
Q.13 Unchecked parameters
68 Annex X (informative)Cross-references to IEC 60738-1:2009
Table X.1 – Cross-references to the previous edition
70 Bibliography

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