IEC 60749-13-2018 pdf download.Semiconductor devices – Mechanical and climatic test methods – Part 13: Salt atmosphere.
This part of IEC 60749 describes a salt atmosphere test that determines the resistance of semiconductor devices to corrosion. It is an accelerated test that simulates the effects of severe sea-coast atmosphere on all exposed surfaces. It is only applicable to those devices specified for a marine environment.
The salt atmosphere test is considered destructive.
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.IEC 60749-13 pdf download.