1、Designation: B845 97 (Reapproved 2013)Standard Guide forMixed Flowing Gas (MFG) Tests for Electrical Contacts1This standard is issued under the fixed designation B845; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 The techniques described in this guide pertain to mixedflowing gas (MFG) tests containing species that are applied toeval
3、uate devices containing electrical contacts such as sliprings, separable connectors, electromechanical relays or switchcontacts. These techniques may be relevant to other devices,but it is the responsibility of the user to determine suitabilityprior to testing.1.2 The MFG tests described in this gui
4、de are designed toaccelerate corrosive degradation processes. These accelera-tions are designed such that the degradation occurs in a muchshorter time period than that expected for such processes in theintended application environment of the device being tested.Application environments can vary cont
5、inuously from benignto aggressively corrosive. Connectors and contacts withinclosed electronic cabinets may be affected by an environmentof different severity than the environment on the outside ofsuch cabinets. In general, indoor environments are differentthan outdoor environments. The MFG tests de
6、scribed herein,being discrete embodiments of specific corrosive conditions,cannot be representative of all possible application environ-ments. It is the responsibility of the test specifier to assure thepertinence of a given test condition to the specifiers applica-tion condition.1.3 The MFG tests d
7、escribed herein are not designed toduplicate the actual intended application environment of thedevice under test. An extended bibliography that providesinformation which is useful to test specifiers to assist them inselecting appropriate test methods is included in this guide.The bibliography covers
8、 the scope from application conditioncharacterization, single and multiple gas effects, and materialand product effects to key application and test variables as wellas discussions of atmospheric corrosion processes.1.4 The values stated in SI units are to be regarded asstandard. No other units of me
9、asurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to become familiarwith all hazards including those identified in the appropriateMaterial Safety Data S
10、heet (MSDS) for this product/materialas provided by the manufacturer, to establish appropriatesafety and health practices, and determine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B542 Terminology Relating to Electrical Contacts and TheirUseB80
11、8 Test Method for Monitoring ofAtmospheric CorrosionChambers by Quartz Crystal MicrobalancesB810 Test Method for Calibration ofAtmospheric CorrosionTest Chambers by Change in Mass of Copper CouponsB825 Test Method for Coulometric Reduction of SurfaceFilms on Metallic Test SamplesB826 Test Method for
12、 Monitoring Atmospheric CorrosionTests by Electrical Resistance ProbesB827 Practice for Conducting Mixed Flowing Gas (MFG)Environmental Tests2.2 Other Documents:EIA-364B-TP65 Mixed Industrial Gas Test Procedure3IEC Standard 68-242 Basic Environmental TestingProcedures, Test KcSulphur Dioxide Test fo
13、r Contacts andConnections4IEC Standard 68-243 Basic Environmental TestingProcedures, Test KdHydrogen Sulfide Test for Contactsand Connections4IEC Technical Trend Document 68-260 TTD Environmen-tal Testing, Corrosion Tests in Artificial Atmosphere atVery Low Concentration of Polluting Gas(es)4IEC 68-
14、260 (second edition) Environmental TestingPart2: Teststest Ke: Flowing mixed gas corrosion test, 19951This guide is under the jurisdiction of ASTM Committee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B02.11 onElectrical Contact Test Methods.Current edition ap
15、proved Aug. 1, 2013. Published August 2013. Originallyapproved in 1993. Last previous edition approved in 2008 as B845 97 (2008)2.DOI: 10.1520/B0845-97R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM
16、Standards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Electronic Industries Alliance (EIA), 2500 Wilson Blvd.,Arlington, VA 22201, http:/www.eia.org.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New Yor
17、k, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1IEEE P1156.1 Environmental Specifications for ComputerModules (Draft 4 June 10, 1992unapproved)53. Terminology3.1 Terms relevant to this guide are defined
18、 in TerminologyB542 except as noted in the following section.3.2 Other term:3.2.1 mixed flowing gas test, na laboratory test conductedin air that flows through a test chamber in which thetemperature, relative humidity, concentrations of gaseouspollutants, and other critical variables are carefully d
19、efined,monitored and controlled.4. Significance and Use4.1 Preservation of a conducting surface on electrical con-tact is vital to the continued functioning of such contacts.Contamination of the surface with insulating layers formed bycorrosion processes is one potential hazard. Laboratory testingof
20、 contacts in MFG tests is used to assess the effectiveness ofdesign features and materials.4.2 MFG tests are used in development studies of processesand materials for contacts. For example, coupon specimensmay be exposed to MFG tests to evaluate new contactmaterials, layers of new coating materials
21、on a supportingsubstrate, reduced coating thicknesses, or protective surfacetreatments.4.3 MFG tests are also employed to test the durability of afinished product with respect to atmospheric corrosion. Forexample, finished connectors may be exposed to a MFG testand their performances compared agains
22、t each other or againsta set of fixed requirements. Relays or switch contacts may beexposed in the operated and non-operated conditions to com-pare performance.4.4 MFG tests are useful for determining the effectivenessof connector housings and shrouds as barriers to ingress ofatmospheric corrodants
23、to the contact surfaces. These tests canalso be used to assess the screening of the metal-to-metalcontact areas of mated connectors.4.5 MFG tests are employed as qualification tests to deter-mine connector failure rates in application environments forwhich correlation between test and application ha
24、s previouslybeen established.4.6 This guide provides test conditions which are to beapplied in conjunction with Practice B827 which defines therequired test operation and certification procedures, tolerances,and reporting requirements. Where the test specifier requirescertifications or tolerances di
25、fferent than those provided inPractice B827, the required certifications or tolerances shall bepart of the test specification. Differences from the specifica-tions in Practice B827 shall be reported in the test reportprovided by the test operator to the test specifier. Specificationof one of the tes
26、t conditions defined in this document in theform of a statement such as, “Parts shall be tested in accor-dance with ASTM B845 Method Z.”, implicitly requires testcondition, Z, applied according to Practice B827.5. Procedure5.1 Decide upon a test plan appropriate for the contactsbeing evaluated. Cons
27、ider test parameters such aspreconditioning, performance measurement and other evalua-tion techniques, and experimental controls.5.2 Select a MFG test and exposure length appropriate forthe parts being evaluated. Table 1 lists a number of such teststhat have been documented in the technical literatu
28、re. The nextsection provides brief discussions of the origins and intendedpurpose of each of the methods.6. Abstracts of Methods6.1 Method AMethod A was originally developed as ahighly accelerated test to stress equipment that might beexposed to environments with high levels of air pollution fromcom
29、bustion of high sulfur coal (1).6The method is included inthis list for completeness. It is generally not consideredrealistic for evaluation of electronic equipment for the vastmajority of applications. Typical exposure time is 4, 10 or 21days, depending upon the specification for the product undert
30、est.6.2 Method BMethod B was originally developed as aEuropean standard, and has largely been replaced by methodswith lower levels of sulfur bearing gases (2). The method isincluded in this list for completeness. It is generally notconsidered realistic for evaluation of electronic equipment forthe v
31、ast majority of applications. Typical exposure time is 4, 10or 21 days, depending upon the specification for the productunder test.6.3 Method CMethod C was developed in Europe as analternative to Method A in response to requests for a lessaggressive test that would simulate exposures in less aggres-
32、sive environments (3,4). Method C may simulate the majorityof usage environments better than Method A. Typical exposuretime is 4, 10 or 21 days depending upon the specification forthe product under test.6.4 Method DMethod D was developed in Europe as analternative to Method B for the same reasons ci
33、ted in the abovediscussion of Method C (3,4). Typical exposure time is 4, 10 or21 days, depending upon the specification for the productunder test.6.5 Method EMethod E was developed in Europe as a firststep toward a test containing more than one pollutant gas (3,4).Typical exposure time is 4, 10 or
34、21 days depending upon thespecification for the product under test.6.6 Method G, H, and KGeneral InformationThesemethods are often called the Battelle Class II, III, and IV Tests75Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),445 Hoes Ln., P.O. Box 1331, Piscataway, N
35、J 08854-1331, http:/www.ieee.org.6The boldface numbers in parentheses refer to a list of references at the end ofthis guide.7It was found that the lack of electrical corrosion failure mechanisms in Class Ienvironments made it unnecessary to develop a Class 1 MFG Test.B845 97 (2013)2respectively, sin
36、ce they were developed by the Battelle Colum-bus Laboratories after an extensive study of electronic equip-ment operating conditions (5). The test conditions were theresult of correlation studies between corrosion products andmechanisms, and test and application conditions, in order toobtain a valid
37、 estimate of the corrosion response in theexpected electronic service environments. From this study, itwas concluded that most operating or application environmentsfor electrical connectors and electronic components can becategorized by a limited number of Severity Classes, which canbe simulated, an
38、d their effects accelerated, by adjusting thecritical parameters of the MFG test.6.6.1 The descriptions in reference (5) of operating environ-ment Classes I through IV are as follows: Class I is character-ized by formation of oxides on copper coupons and no visibleattack on porous gold plated, nicke
39、l underplated, coppercoupons (Au/Ni/Cu) Class II is characterized by pore corrosionof Au/Ni/Cu coupons and formation of oxides and complexcopper hydroxy chlorides on copper coupons. Class III ischaracterized by pore and tarnish creepage corrosion of Au/Ni/Cu coupons and the formation of oxides, sulf
40、ides and otherunknown corrosion products on copper coupons. Class IV ischaracterized by tarnish creepage on Au/Ni/Cu coupons andcopper coupon corrosion products similar to Class III exceptthat sulfide presence greatly exceeds oxide presence whereasfor Class III, the oxide presence is equivalent to t
41、he sulfidepresence (5).6.6.1.1 Method GMethod G accelerates the effects ofBattelle Class II environments. These correspond to conditionsthat are often found in business offices or control rooms that areassociated with light industrial areas or where environmentalcontrols are not operating effectivel
42、y and continuously (5,6).Light tarnish creepage corrosion has been reported to be foundin Class II gas tests. Typical industry practice has been toexpose test hardware (such as connectors) to this test for 1 to3 weeks.86.6.1.2 Method HMethod H accelerates the effects ofBattelle Class III environment
43、s. These correspond to manyindustrial and related locations (including many storage areas)where moderate amounts of pollutants are present in poorlycontrolled environments. These might be found nearer toprimary sources of atmospheric pollutant gases or in industrialenvironments where there are a mul
44、tiplicity of sources for8EIA 364 TP-65 designates these test conditions as Environmental Class II (8).TABLE 1 Test Conditions of Mixed Flowing Gas TestsASTMMethodH2S ppbASO2ppbACl2ppbANO2ppb Temp. C RH %AirChanges(# /h)Air Velocity(m/h)Duration(days)Source Ref. NotesA 25,0005000252B75520-60 4, 10, 2
45、1 Kc(1)CB 12,5002500252B7553-5 20-60 4, 10, 21 Kd(2)C 500100251B7533-5 60 4, 10, 21 KeMethod A(3,4)D 10020251B7533-5 60 4, 10, 21 KeMethod B(3,4)E 10020500100251B7533-10 60 4, 10, 21 KeIEC 68-2-60TestMethod 1(3,4)G10+0/410+0/2200253027023-8 BattelleClass II(5,16,17)(8)DH 10010205200253027523-8 Batte
46、lleClass III(5,16,17)(8)E,FK 20010505200255027523-8 BattelleClass IV(5,8)L405 %3505 %315 %6105 %300.57021832 G1(T) (9)M 105 20020 105 20020 251B75 3 3-10 10, 21 KeIEC 68-2-60(3,4,11)(12)N10+0/42002510+ 0/220025302702perASTMB827perASTMB8275-30 Telecomcentraloffice(14,15)O 105 10020 103 20050 301 702
47、perASTMB827perASTMB82710, 20 Telecomcentraloffice(16,17)P 10020 20050 205 20050 301 702 perASTMB827perASTMB82720 Telecomuncontrolledenvironment(16,17)Notes:AGas concentrations in ppb refer to parts per billion (1 in 109) volume per volume (vol/vol) in air.BThe test temperature of 25C may require ref
48、rigeration in order to assure compliance with specified temperature and humidity variation limits.CCarbon dioxide, 4500 parts per million (vol/vol) maximum.DReferences (16 and 17) show NO2level as 100 ppb and temperature as 25C while reference (5) shows the values in the table above; difference in c
49、orrosion of copperis minor between the two sets of conditions per private communication dated April 26, 1991, W. H. Abbott to E. Sproles.ERelative humidity of 75 % (as shown in References (16 and 17) is the recommended test condition for Class III per private communication dated April 26, 1991, W. H.Abbott to E. Sproles.FTest conditions are defined in purchase contract.B845 97 (2013)3pollutant gases within a region such that all businesses in suchregions are susceptible. Potential failure mec
