IEC 60539-2-2003 pdf – Directly heated negative temperature coefficient thermistors – Part 2: Sectional specification – Surface mount negative temperature coefficient thermistors.
1 General 1.1 Scope This part of IEC 60539 is applicable to surface mount directly heated negative temperature coefficient thermistors, typically made from transition metal oxide materials with semiconducting properties. These thermistors have metallized connecting pads or soldering strips and are intended to be mounted directly on to substrates for hybrid circuits or on to printed boards. 1.2 Normative 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 edition of the referenced document (including any amendments) applies. IEC 60068-2-2:1974, Environmental testing – Part 2: Tests – Tests B: Dry heat Amendment 1 (1993) Amendment 2 (1994) IEC 60068-2-14:1984, Environmental testing – Part 2: Tests – Test N: Change of temperature Amendment 1 (1986) IEC 60068-2-30:1980, Environmental testing – Part 2: Tests – Test Db and guidance: Damp heat, cyclic (12 + 12-hour cycle) Amendment 1 (1985) IEC 60068-2-58:1999, Environmental testing – Part 2-58: Tests – Test Td: Test methods for solderability, resistance to dissolution of metallization and to soldering heat of surface mounting devices (SMD) IEC 60068-2-78: Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady state IEC 60410:1973, Sampling plans and procedures for inspection by attributes IEC 60539-1:2002, Directly heated negative temperature coefficient thermistors – Part 1: Generic specification
NOTE The information given in 1.3.1 may for convenience, be presented in tabular form. The following information shall be given in each detail specification and the values quoted shall preferably be selected from those given in the appropriate clause of this sectional specification. 1.3.1 Outline drawing and dimensions There shall be an illustration of the thermistor as an aid to easy recognition and for comparison with others. Dimensions and their associated tolerances, which affect inter- changeability and mounting, shall be given in the detail specification. All dimensions shall preferably be stated in millimetres; however, when the original dimensions are given in inches, the converted metric dimensions in millimetres shall be added. Normally, the numerical values shall be given for the length, width and height of the body. When necessary, for example when a number of items are covered by a detail specification, the dimensions and their associated tolerances shall be placed in a table below the drawing. When the configuration is other than described above, the detail specification shall state such dimensional information as will adequately describe the thermistor. 1.3.2 Mounting The detail specification shall give guidance on methods of mounting for normal use. Mounting for test and measurement purposes (when required) shall be in accordance with 4.27 of IEC 60539-1. 1.3.3 Ratings and characteristics 188.8.131.52 Particular characteristics Additional characteristics may be listed when they are considered necessary to specify the component adequately for design and application purposes. 184.108.40.206 Marking See 2.4 of IEC 60539-1. 1.4 Terminology See 2.2 of IEC 60539-1.
3 Quality assessment procedures 3.1 Primary stage of manufacture The primary stage of manufacture is defined as the initial mixing process of ingredients. 3.2 Structurally similar components Surface mount thermistors may be grouped as structurally similar for the purpose of forming inspection lots provided that the requirements of 3.1 of IEC 60539-1 are met, with the following addition. For the shear test and the substrate bending test, devices may be grouped if they have been made on the same production line, have the same dimensions, internal structure and external finish. 3.3 Qualification approval procedures 3.3.1 The manufacturer shall comply with 3.4 of IEC 60539-1. 3.4 Quality conformance inspection Blank detail specifications associated with this specification shall prescribe the test schedule for quality conformance inspection. This schedule shall also specify the grouping, sampling and periodicity for the lot-by-lot and periodic inspection. Inspection levels and sampling plans shall be selected from those given in IEC 60410. If required, more then one test schedule may be specified. 3.4.1 Qualification approval on the basis of the fixed sample size procedure a) Sampling The sample shall be representative of the range of thermistors for which approval is sought. This may or may not be the complete range covered by the detail specification. The sample shall consist of specimens having the lowest, highest and middle-rated zero- power resistance of each case size.