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BS EN 60738-1:2022

BS EN 60738-1:2022

$198.66

Thermistors. Directly heated positive temperature coefficient – Generic specification

Published By Publication Date Number of Pages
BSI 2022 68
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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.

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PDF Pages PDF Title
2 undefined
3 English
CONTENTS
8 FOREWORD
10 1 Scope
2 Normative references
11 3 Terms and definitions
13 Figures
Figure 1 – Typical resistance-temperature characteristicand definitions for PTC thermistors (at zero power)
14 Figure 2 – Typical R-TNF characteristic for PTC thermistors in sensor applications
15 Figure 3 – Typical current/voltage characteristic for PTC thermistors
18 Figure 4 – Iin against t at Udc
Figure 5 – Iin against t at URMS
20 4 General requirements
4.1 Units and symbols
21 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
22 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
23 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
24 5.4.2 Printed wiring board and land pattern
5.4.3 Wave soldering method
5.4.4 Reflow soldering method
25 6 Electrical tests and measurements
6.1 Zero-power resistance
6.1.1 General
6.1.2 Measurement procedures
26 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
27 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
28 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
29 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
30 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
31 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
33 6.10.3 Requirements
6.11 Tripping current and tripping time
6.12 Non-tripping current
6.13 Residual current
34 6.14 Surface temperature
Figure 9 – Circuit for surface temperature measurement
35 6.15 Inrush current
6.15.1 Measuring circuit
6.15.2 Measuring method
Figure 10 – Measuring circuit
36 6.16 Energy by discharge
6.16.1 Measuring circuit
6.16.2 Measuring method
Figure 11 – Measuring circuit
37 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
38 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
39 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
40 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
41 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
42 8.3 Damp heat, steady state
8.4 Endurance
8.4.1 Endurance at room temperature (cycling)
43 8.4.2 Endurance at upper category temperature
44 8.4.3 Endurance at maximum operating temperature and maximum voltage
45 8.4.4 Cold environment electrical cycling
Figure 12 – Circuit for endurance at maximum operating temperatureand maximum voltage
46 8.4.5 Thermal runaway
9 Test related to component assembly
9.1 Solderability
9.1.1 General
9.1.2 Thermistors with leads
47 9.1.3 Surface mount thermistors
9.2 Resistance to soldering heat
9.2.1 General
9.2.2 Test conditions
48 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
49 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
50 A.3 Mounting for surface mount thermistors
Figure A.2 – Example of a preferred mounting methodfor thermistors with wire terminations
51 Figure A.3 – Example of a preferred mounting method for surface mount thermistors
Table A.1 – Recommended land dimensions
52 Annex B (informative)Mounting for temperature measurements
Figure B.1 – Example of a preferred mounting method for temperature measurementon cylindrical heating elements
53 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
54 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
55 Q.6.4 Qualification approval based on the fixed sample size procedure
57 Table Q.1 – Fixed sample size test schedule for qualification approval of thermistorsfor current limitation – Assessment level EZ
58 Table Q.2 – Fixed sample size test schedule for qualification approval of thermistorsfor use as heating elements – Assessment level EZ
59 Table Q.3 – Fixed sample size test schedule for qualification approval of thermistorsfor inrush current application – Assessment level EZ
60 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
61 Q.6.7 Quality conformance inspection
Table Q.5 – Quality conformance inspection for lot-by-lot inspection
62 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
63 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
64 Annex X (informative)Cross-references to IEC 60738-1:2009
Table X.1 – Cross-references to the previous edition
66 Bibliography

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BS EN 60738-1:2022
$198.66