Thermistors - Directly heated positive temperature coefficient - Part 1: Generic specification

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.

Direkt geheizte temperaturabhängige Widerstände mit positivem Temperaturkoeffizienten – Teil 1: Fachgrundspezifikation

Thermistances - Coefficient de température positif à chauffage direct - Partie 1: Spécification générique

Termistorji - Neposredno ogrevani s pozitivnim temperaturnim koeficientom - 1. del: Splošna specifikacija

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Status
Not Published
Current Stage
4020 - Enquiry circulated
Due Date
05-Nov-2021
Completion Date
05-Nov-2021

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SLOVENSKI STANDARD
oSIST prEN IEC 60738-1:2022
01-januar-2022
Termistorji - Neposredno ogrevani s pozitivnim temperaturnim koeficientom - 1.
del: Splošna specifikacija
Thermistors - Directly heated positive temperature coefficient - Part 1: Generic
specification

Thermistances - Coefficient de température positif à chauffage direct - Partie 1:

Spécification générique
Ta slovenski standard je istoveten z: prEN IEC 60738-1:2021
ICS:
31.040.30 Termistorji Thermistors
oSIST prEN IEC 60738-1:2022 en

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

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oSIST prEN IEC 60738-1:2022
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oSIST prEN IEC 60738-1:2022
40/2880/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60738-1 ED4
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2021-11-05 2022-01-28
SUPERSEDES DOCUMENTS:
40/2832/CD, 40/2864/CC
IEC TC 40 : CAPACITORS AND RESISTORS FOR ELECTRONIC EQUIPMENT
SECRETARIAT: SECRETARY:
Netherlands Mr Ronald Drenthen
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if any,
in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY

SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING

Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.

This document is still under study and subject to change. It should not be used for reference purposes.

Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they

are aware and to provide supporting documentation.
TITLE:

Thermistors - Directly heated positive temperature coefficient - Part 1: Generic specification

PROPOSED STABILITY DATE: 2030
NOTE FROM TC/SC OFFICERS:

Copyright © 2021 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this

electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.

You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without

permission in writing from IEC.
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oSIST prEN IEC 60738-1:2022
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1 CONTENTS

3 FOREWORD ........................................................................................................................... 7

4 INTRODUCTION ..................................................................................................................... 9

5 1 Scope ............................................................................................................................ 10

6 2 Normative references .................................................................................................... 10

7 3 Terms and definitions .................................................................................................... 11

8 4 General requirements .................................................................................................... 20

9 4.1 Units and symbols................................................................................................. 20

10 4.2 Preferred values ................................................................................................... 20

11 4.2.1 Climatic categories ........................................................................................ 20

12 4.2.2 Spacings ....................................................................................................... 20

13 4.3 Marking ................................................................................................................. 21

14 4.3.1 General ......................................................................................................... 21

15 4.3.2 Coding ........................................................................................................... 21

16 5 General provisions for measurements and test method .................................................. 21

17 5.1 General ................................................................................................................. 21

18 5.2 Standard conditions for testing .............................................................................. 21

19 5.2.1 Standard atmospheric conditions for testing .................................................. 21

20 5.2.2 Error of measurement .................................................................................... 22

21 5.3 Drying and recovery .............................................................................................. 22

22 5.3.1 Drying ............................................................................................................ 22

23 5.3.2 Recovery ....................................................................................................... 22

24 5.3.3 Shock test severities...................................................................................... 22

25 5.3.4 Vibration severities ........................................................................................ 22

26 5.4 Mounting (for surface mount thermistors only) ...................................................... 23

27 5.4.1 General ......................................................................................................... 23

28 5.4.2 Printed wiring board and land pattern ............................................................ 23

29 5.4.3 Wave soldering method ................................................................................. 23

30 5.4.4 Reflow soldering method ............................................................................... 23

31 6 Electrical tests and measurements ................................................................................ 24

32 6.1 Zero-power resistance .......................................................................................... 24

33 6.1.1 General ......................................................................................................... 24

34 6.1.2 Measurement procedures .............................................................................. 24

35 6.1.3 Requirements ................................................................................................ 24

36 6.2 Temperature coefficient of resistance ................................................................... 25

37 6.2.1 General ......................................................................................................... 25

38 6.2.2 Requirements ................................................................................................ 25

39 6.3 Insulation resistance (for insulated types only) ...................................................... 25

40 6.3.1 General ......................................................................................................... 25

41 6.3.2 Test methods ................................................................................................. 25

42 6.3.3 Applied voltage .............................................................................................. 26

43 6.3.4 Requirements ................................................................................................ 26

44 6.4 Voltage proof (for insulated types only) ................................................................. 26

45 6.4.1 General ......................................................................................................... 26

46 6.4.2 Test methods ................................................................................................. 26

47 6.4.3 Test voltage ................................................................................................... 26

48 6.4.4 Requirements ................................................................................................ 26

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49 6.5 Resistance/temperature characteristic .................................................................. 26

50 6.5.1 General ......................................................................................................... 26

51 6.5.2 Test methods ................................................................................................. 26

52 6.5.3 Requirements ................................................................................................ 26

53 6.6 Dissipation factor at U (δ) ............................................................................... 27

max

54 6.6.1 General ......................................................................................................... 27

55 6.6.2 Preconditioning .............................................................................................. 27

56 6.6.3 Test circuit ..................................................................................................... 27

57 6.6.4 Test methods ................................................................................................. 27

58 6.6.5 Requirements ................................................................................................ 28

59 6.7 Response time by ambient temperature change (t ) ............................................. 28

60 6.7.1 General ......................................................................................................... 28

61 6.7.2 Preconditioning .............................................................................................. 28

62 6.7.3 Test procedures............................................................................................. 28

63 6.7.4 Measurement procedures .............................................................................. 28

64 6.7.5 Requirements ................................................................................................ 28

65 6.8 Response time by power change (t ) .................................................................... 29

66 6.8.1 Mounting ....................................................................................................... 29

67 6.8.2 Test methods ................................................................................................. 29

68 6.9 Thermal time constant by ambient temperature change (τ ) .................................. 29

69 6.10 Thermal time constant by cooling (τ ) ................................................................... 29

70 6.10.1 Mounting ....................................................................................................... 29

71 6.10.2 Test methods ................................................................................................. 29

72 6.10.3 Requirements ................................................................................................ 31

73 6.11 Tripping current and tripping time ......................................................................... 31

74 6.12 Non-tripping current .............................................................................................. 31

75 6.13 Residual current ................................................................................................... 32

76 6.14 Surface temperature ............................................................................................. 32

77 6.15 Inrush current ....................................................................................................... 33

78 6.15.1 Measuring circuit ........................................................................................... 33

79 6.15.2 Measuring method ......................................................................................... 33

80 6.16 Energy by discharge ............................................................................................. 34

81 6.16.1 Measuring circuit ........................................................................................... 34

82 6.16.2 Measuring method ......................................................................................... 34

83 7 Mechanical test and measurements ............................................................................... 34

84 7.1 Visual examination and check of dimensions ........................................................ 34

85 7.1.1 Visual examination ........................................................................................ 34

86 7.1.2 Marking ......................................................................................................... 34

87 7.1.3 Dimensions (gauging) .................................................................................... 35

88 7.1.4 Dimensions (detail) ........................................................................................ 35

89 7.2 Robustness of terminations ................................................................................... 35

90 7.2.1 Test Ua – Tensile ........................................................................................ 35

91 7.2.2 Test Ub – Bending (half of the samples) (not applicable to thermistors

92 encapsulated in glass or in envelopes) .......................................................... 35

93 7.2.3 Test Uc – Torsion (remaining samples) .......................................................... 35

94 7.2.4 Visual examination ........................................................................................ 36

95 7.2.5 Final measurements and requirements .......................................................... 36

96 7.3 Vibration ............................................................................................................... 36

97 7.4 Shock ................................................................................................................... 36

98 7.5 Shear (adhesion) test............................................................................................ 37

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99 7.5.1 Test conditions .............................................................................................. 37

100 7.5.2 Test methods ................................................................................................. 37

101 7.5.3 Requirements ................................................................................................ 37

102 7.6 Substrate bending test .......................................................................................... 37

103 7.6.1 Mounting ....................................................................................................... 37

104 7.6.2 Initial measurements ..................................................................................... 37

105 7.6.3 Test procedures............................................................................................. 37

106 7.6.4 Measurements ............................................................................................... 37

107 7.6.5 Requirements ................................................................................................ 37

108 7.6.6 Final inspection and requirements ................................................................. 37

109 8 Environmental and climatic tests ................................................................................... 37

110 8.1 Rapid change of temperature ................................................................................ 37

111 8.2 Climatic sequence................................................................................................. 38

112 8.2.1 Initial measurements ..................................................................................... 38

113 8.2.2 Dry heat ........................................................................................................ 38

114 8.2.3 Damp heat (cyclic), first cycle ........................................................................ 38

115 8.2.4 Cold .............................................................................................................. 38

116 8.2.5 Low air pressure ............................................................................................ 38

117 8.2.6 Damp heat (cyclic), remaining cycles ............................................................. 38

118 8.2.7 Final measurements ...................................................................................... 39

119 8.3 Damp heat, steady state ....................................................................................... 39

120 8.4 Endurance ............................................................................................................ 39

121 8.4.1 Endurance at room temperature (cycling) ...................................................... 39

122 8.4.2 Endurance at upper category temperature ..................................................... 40

123 8.4.3 Endurance at maximum operating temperature and maximum voltage ........... 41

124 8.4.4 Cold environment electrical cycling ................................................................ 42

125 8.4.5 Thermal runaway ........................................................................................... 43

126 9 Test related to component assembly.............................................................................. 43

127 9.1 Solderability .......................................................................................................... 43

128 9.1.1 General ......................................................................................................... 43

129 9.1.2 Thermistors with leads ................................................................................... 43

130 9.1.3 Surface mount thermistors ............................................................................. 44

131 9.2 Resistance to soldering heat ................................................................................. 44

132 9.2.1 General ......................................................................................................... 44

133 10 Quality assessment procedures ..................................................................................... 45

134 10.1 General ................................................................................................................. 45

135 10.1.1 Applicability of qualification approval ............................................................. 45

136 10.2 Primary stage of manufacture ............................................................................... 46

137 10.3 Subcontracting ...................................................................................................... 46

138 10.4 Structurally similar components ............................................................................ 46

139 10.4.1 For electrical tests ......................................................................................... 46

140 10.4.2 For environmental tests ................................................................................. 46

141 10.4.3 For visual inspection ...................................................................................... 46

142 10.4.4 For endurance tests ....................................................................................... 46

143 10.5 Qualification approval procedures ......................................................................... 46

144 10.5.1 Eligibility for qualification approval ................................................................. 46

145 10.5.2 Application for qualification approval ............................................................. 46

146 10.5.3 Test procedure for qualification approval ....................................................... 47

147 10.5.4 Qualification approval based on the fixed sample size procedure................... 47

148 10.5.5 Granting of qualification approval .................................................................. 53

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149 10.5.6 Maintenance of qualification approval ............................................................ 53

150 10.5.7 Quality conformance inspection ..................................................................... 53

151 10.6 Rework and repair................................................................................................. 54

152 10.6.1 Rework .......................................................................................................... 54

153 10.6.2 Repair ........................................................................................................... 54

154 10.7 Release for delivery .............................................................................................. 54

155 10.7.1 General ......................................................................................................... 54

156 10.7.2 Release for delivery under qualification approval before the completion

157 of group B tests ............................................................................................. 54

158 10.8 Certified test records of released lots .................................................................... 55

159 10.9 Delayed delivery ................................................................................................... 55

160 10.10 Alternative test methods ....................................................................................... 55

161 10.11 Manufacture outside the geographical limits of IECQ NSIs .................................... 55

162 10.12 Unchecked parameters ......................................................................................... 55

163

164 Annex A (informative) Mounting for electrical measurements ............................................... 56

165 A.1 Mounting for thermistors without wire terminations ................................................ 56

166 A.2 Mounting for thermistors with wire terminations ..................................................... 57

167 A.3 Mounting for surface mount thermistors ................................................................ 57

168 Annex B (informative) Mounting for temperature measurements .......................................... 59

169 Annex X (informative) Cross references to the prior revision of this standard ...................... 60

170

171 Figure 1 – Typical resistance-temperature characteristic and definitions for PTC

172 thermistors (at zero power) ................................................................................................... 13

173 Figure 2 – Typical R-TNF characteristic for PTC thermistors in sensor applications .............. 14

174 Figure 3 – Typical current/voltage characteristic for PTC thermistors .................................... 14

175 Figure 4 – I against t at U ............................................................................................... 17

in dc

176 Figure 5 – I against t at U ........................................................................................... 18

in RMS

177 Figure 6 – Dissipation factor test circuit ................................................................................ 27

178 Figure 7 – Temperature gradient ........................................................................................... 28

179 Figure 8 – Circuit for measurement of thermal time constant by cooling ................................ 30

180 Figure 9 – Circuit for surface temperature measurement ....................................................... 33

181 Figure 10 – Measuring circuit ................................................................................................ 33

182 Figure 11 – Measuring circuit ................................................................................................ 34

183 Figure 12 – Circuit for endurance at maximum operating temperature and maximum

184 voltage .................................................................................................................................. 42

185 Figure A.1 – Example of a preferred mounting method for thermistors without wire

186 terminations .......................................................................................................................... 56

187 Figure A.2 – Example of a preferred mounting method for thermistors with wire

188 terminations .......................................................................................................................... 57

189 Figure A.3 – Example of a preferred mounting method for surface mount thermistors ........... 58

190 Figure B.1 – Example of a preferred mounting method for temperature measurement

191 on cylindrical heating elements ............................................................................................. 59

192

193 Table 1 – Creepage distances and clearances ...................................................................... 20

194 Table 2 – Test severities of Vibration .................................................................................... 22

195 Table 3 – Tensile force ......................................................................................................... 35

196 Table 4 – Number of cycles per climatic category ................................................................. 38

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197 Table 5 – Fixed sample size test schedule for qualification approval of thermistors for

198 current limitation – Assessment level EZ ............................................................................... 49

199 Table 6 – Fixed sample size test schedule for qualification approval of thermistors for

200 use as heating elements – Assessment level EZ ................................................................... 50

201 Table 7 – Fixed sample size test schedule for qualification approval of thermistors for

202 inrush current application – Assessment level EZ ................................................................. 51

203 Table 8 – Fixed sample size test schedule for qualification approval of thermistors for

204 use as temperature sensing elements – Assessment level EZ ............................................... 52

205 Table 9 – Quality conformance inspection for lot-by-lot inspection ........................................ 53

206 Table 10 – Quality conformance inspection for periodic testing ............................................. 54

207 Table A.1 – Recommendation land dimensions ..................................................................... 58

208 Table X.1 – Reference to IEC 60738-1 for clause/subclause or annex .................................. 60

209
210
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211 INTERNATIONAL ELECTROTECHNICAL COMMISSION
212 ____________
213
214 THERMISTORS – DIRECTLY HEATED POSITIVE
215 TEMPERATURE COEFFICIENT –
216
217 Part 1: Generic specification
218
219
220 FOREWORD

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239 tr
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