GB/T 2423.19-2013 Environmental testing - Part 2 : Test methods - Test Kc : Sulphur dioxide test for contacts and connections
1 Scope and object
This test:
- is intended to provide accelerated means to assess the corrosive effects of atmospheres polluted with sulphur dioxide on contacts and connections;
- is particularly suitable for giving information on a comparative basis;
- is not suitable as a general corrosion test, i.e. it may not predict the behaviour of contacts and connections in industrial atmospheres.
Note: In view of the limited information to be obtained from accelerated corrosion tests, particular attention shall be paid to the guidance on this test given in IEC GB/T 2424.11. Reference should also be made to GB/T 2424.10.
The object of this test is:
a) to determine the influence of atmospheres containing sulphur dioxide on the contact properties of precious metal or precious metal-covered contacts and connections, excluding contacts consisting of silver and some of its alloys;
b) to check solderless connections with regard to their tightness or effectiveness. In all tests, the major criterion of performance will be the change in contact resistance caused by exposure to the sulphur dioxide test atmosphere.
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 60512-2-1:2002 Connectors for electronic equipment - Tests and measurements - Part 2-1: Electrical continuity and contact resistance tests - Test 2a: Contact resistance - Millivolt level method
3 Test apparatus
3.1 General
The test apparatus consists of a climatic system, test enclosures, a gas delivery system and means for measuring gas concentration, detailed in Annex A.
3.2 Test chamber
The test chamber and its auxiliary parts shall be made of materials that do not react with or absorb sulphur dioxide and which do not influence the corrosive effects of the test atmosphere. The mixture of air and sulphur dioxide may enter and leave the chamber through tubes with sufficiently large diameters such that the total flow through the chamber is at least three, but not more than five, changes of the atmosphere per hour. The exhaust from the chamber shall not be allowed to enter the laboratory.
The detailed construction of the chamber including the method of producing the test atmosphere is optional, provided that:
a) the conditions in that part of the chamber occupied by the specimens are within the specified limits;
b) the specimens under test are protected from direct exposure to the incoming gas flow;
c) arrangements are made to move the specimens through the atmosphere at an average rate of 20 m/h to 60 m/h (approximately 6 mm/s to 17 mm/s) or alternatively to gently stir the atmosphere, obtaining a similar relative velocity between atmosphere and specimens;
d) condensation does not occur inside the test chamber;
e) the test chamber is not exposed to direct sunlight and the level of illumination (provided by daylight or by incandescent or fluorescent lamps) measured within the test chamber at the site of any exposed surface is 50 lx to 300 lx.
An example of a suitable test chamber is given in Annex A.
4 Test gas
The test gas within the chamber shall satisfy the following conditions:
- sulphur dioxide: 25×10⁻⁶ ±5×10⁻⁶ vol/vol. This shall be taken as the total oxides of sulphur expressed as SO₂. Small concentrations of sulphur oxides other than SO₂ (such as SO3) are permitted to be present to a maximum concentration of 1 % of the total sulphur oxides;
Contents
Foreword I
1 Scope and object
2 Normative references
3 Test apparatus
4 Test gas
5 Preconditioning
6 Method
7 Details to be specified
Annex A (Informative) Generation of the test atmosphere by direct mixing of sulphur dioxide with air
Annex NA (Informative) Components of GB/T 2423
Bibliography
