IEC 60738-1 pdf download – Thermistors – Directly heated positive temperature coefficient – Part 1: Generic specification

IEC 60738-1 pdf download – Thermistors – Directly heated positive temperature coefficient – Part 1: Generic specification
1 scope
This part of lEC 60738 describes terms and methods of test for positive step-functiontemperature coefficient thermistors，insulated and non-insulated types typically made fromferro-electric semi-conductor materials.
lt establishes standard terms，inspection procedures and methods of test for use in detailspecifications for Qualification Approval and for Quality Assessment Systems for electroniccomponents.
2Normative references
The following referenced documents are indispensable for the application of this document.For dated references, only the edition cited applies. For undated references, the latest editionof the referenced document (including any amendments) applies.
IEC 60027(all parts),Letter symbols to be used in electrical technologyIEC 60050 (all parts),International Electrotechnical Vocabulary (IEv)IEC 60062,Marking codes for resistors and capacitors
IEC 60068-1:1988,Environmental testing – Part 1: General and guidanceAmendment 1 (1992)
lEC 60068-2-1:1990,Environmental testing – Part 2: Tests -Tests A: ColdAmendment 1 (1993)
Amendment 2 (1994)
IEC 60068-2-2:1974，Environmental testing – Part 2: Tests – Tests B: Dry heatAmendment 1 (1993)
IEC 60068-2-6，Environmental testing – Part 2:Tests – Test Fc: Vibration (sinusoidal)IEC 60068-2-11，Environmental testing – Part 2: Tests – Test Ka: Salt mist
IEC 60068-2-13,Environmental testing – Part 2: Tests – Test M: Low air pressure
IEC 60068-2-14:1984,Environmental testing – Part 2:Tests – Test N: Change of temperatureAmendment 1 (1986)
lEC 60068-2-20:1979,Environmental testing – Part 2:Tests -Test T: SolderingAmendment 2(1987)
IEC 60068-2-21，Environmental testing – Part 2-21: Tests – Test U: Robustness ofterminations and integral mounting devices
IEC 60068-2-27，Environmental testing – Part 2:Tests – Test Ea and guidance: ShocklEC 60068-2-29,Environmental testing – Part 2:Tests – Test Eb and guidance:Bump
IEC 60068-2-30:2005，Environmental testing – Part 2: Tests – Test Db: Damp heat,cyclic(12h + 12-hour cycle)
IEC 60068-2-45:1980，Environmental testing – Part 2: Tests – Test XA and guidance -lmmersion in cleaning solvents
IEC 60068-2-58，Environmental testing – Part 2-58: Tests – Test Td: Test methods forsolderability，resistance to dissolution of metallization and to soldering heat of surfacemounting devices (SMD)
IEC 60068-2-78，Environmental testing – Part 2-78:Tests – Test Cab: Damp heat,steadystate
IEC 60294，Measurement of the dimensions of a cylindrical component having two axialterminations
IEC 60410,Sampling plans and procedures for inspection by attributesIEC 60617(all parts)[DB]1: Graphical symbols for diagrams
IEC 60717,Method for determination of the space required by capacitors and resistors withunidirectional terminations
IEC 61249-2-7,Materials for printed boards and other interconnecting structures – Part 2-7:Reinforced base materials clad and unclad – Epoxide woven E-glass laminated sheet ofdefined flammability (vertical burning test), copper-clad
IEC 61760-1，Surface mounting technology – Part 1: Standard method for the specification ofsurface mounting components (SMDs)
IEC Qc 001002-3，Rules of Procedure of the IEC Quality Assessment System for ElectronicComponents (lEcQ) – Part 3: Approval procedures
ISO 1000，Sl units and recommendations for the use of their multiples and of certain otherunits
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
type
group of components having similar design features and the similarity of whose manufacturingtechniques enables them to be grouped together either for qualification approval or for qualityconformance inspection
They are generally covered by a single detail specification
3.2style
variation within a type having specific nominal dimensions and characteristics
3.3
thermistor
thermally sensitive semiconducting resistor which exhibits a significant change in electricalresistance with a change in body temperature
3.4
positive temperature coefficient thermistor
thermistor，the resistance of which increases with its increasing temperature throughout theuseful part of its characteristic
3.5
positive step-function temperature coefficient thermistorPTC
thermistor which shows a step-like increase in its resistance when the increasing temperaturereaches a specific value
A PTC thermistor will show secondary effects which are to be taken into account
3.6
zero-power resistanceR
value of the resistance of a PTC thermistor, at a given temperature，under conditions suchthat the change in resistance due to the internal generation of heat is negligible with respectto the total error of measurement
NOTE Any resistance value of a PTC thermistor is dependent on the value and the mode of the applied voltage(a.c. or d.c.) and. when an a.c.source is used, on the frequency (see 3.8 and 3.9).
3.7
nominal zero-power resistanceRn
d.c. resistance value of a thermistor measured at a specified temperature, preferably at 25 C,with a power dissipation low enough that any further decrease in power will result only in anegligible change in resistance.Zero-power resistance may also be measured using a.c. ifrequired by the detail specification
3.8
voltage dependency
secondary effect，exhibiting a decreasing resistance with increasing voltage across thethermistor when measured at a constant body temperature
3.9
frequency dependency
secondary effect exhibiting a substantial decrease of the positive temperature coefficient ofthe thermistor with increasing frequency