IEC 60749-13:2018 pdf download – Semiconductor devices – Mechanical and climatic test methods – Part 13: Salt atmosphere.
2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements 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 60749-1 4, Semiconductor devices – Mechanical and climatic test methods – Part 14: Robustness of terminations (lead integrity) 3 Terms and definitions No terms and definitions are listed in this document. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp 4 Test apparatus The following items are required for performing the salt atmosphere test. a) Temperature-controlled chamber with suitable non-corrodible rack for supporting devices. All parts within the test chamber which come in contact with test specimens shall be of materials that will not cause electrolytic corrosion. The chamber shall be properly vented to prevent pressure build-up and allow uniform distribution of salt fog. b) Salt solution reservoir adequately protected from the surrounding ambient. The salt concentration shall be 0,5 % to 3,0 % by weight in deionized or distilled water as required to achieve the deposition rates required by 5.4. The salt used shall be sodium chloride containing on the dry basis not more than 0,1 % by weight of sodium iodide and not more than 0,3 % by weight total impurities. The pH of the salt solution shall be maintained between 6,5 and 7,2 when measured at 35 °C ± 3 °C. Only CP grade (dilute solution) hydrochloric acid or sodium hydroxide shall be used to adjust the pH.c) Means for atomizing the salt solution, including suitable nozzles and compressed air supply or a 20 % oxygen, 80 % nitrogen mixture (the gas entering the atomizers shall be free from all impurities such as oil and dirt). d) Means for humidifying the air at a temperature above the chamber temperature. e) Air or inert gas dryer. f) Magnifier(s), 1 × to 3×, 1 0× to 20× and 30× to 60×. 5 Procedure 5.1 Conditioning and maintenance of test chamber The purpose of the cleaning cycle is to assure that all materials which could adversely affect the results of the subsequent tests are removed from the chamber. The chamber shall be cleaned by operating it at 35 °C ± 3 °C with deionized or distilled water as long as necessary. The chamber shall be cleaned each time the salt solution in the reservoir has been used up. Several test runs therefore could be run before cleaning, depending on the size of the reservoir and the specified test condition (see 5.5). When long duration conditions (test conditions C and D, see 5.5) are required, the reservoir may be refilled via auxiliary reservoirs so that the test cycle does not need to be interrupted. After the cleaning cycle, on restarting the chamber, the reservoir shall be filled with salt solution and the chamber shall be stabilized by operating it until the temperature comes to equilibrium, see 5.4. If operation of the chamber is discontinued for more than one week, the remaining salt solution, if any, shall be discarded. Cleaning shall then be performed prior to restarting the test chamber. Intermittent operation of the chamber is acceptable provided the pH and concentration of the salt solution are kept within the limits defined in item b) of Clause 4.5.2 Initial preconditioning of leads Unless otherwise specified, the test specimens shall not be preconditioned. When initial conditioning is specified, the device terminals shall be subjected to a stress in accordance with test condition B of the method specified in IEC 60749-1 4 before the specimens are mounted for the salt atmosphere test. When the sample devices being subjected to the salt atmosphere have already received the required initial conditioning, as part of another test employing the same sample devices, the terminal bend need not be repeated. 5.3 Mounting of test specimens Test specimens shall be positioned so that they do not contact each other, so that they do not shield each other from the freely settling fog, and so that corrosion products and condensate from one specimen does not fall on another. In cases where two orientations are required for testing, the specified sample size shall be divided in half (or as close to one-half as possible). In all cases, inspections following the test in accordance with 5.7 shall be performed on all package surfaces.