1、Designation: B 845 97 (Reapproved 2003)Standard Guide forMixed Flowing Gas (MFG) Tests for Electrical Contacts1This standard is issued under the fixed designation B 845; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 toe
3、valuate 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
4、guide 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 c
5、ontinuously 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
6、 described 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 test
7、s described herein are not designed toduplicate the actual intended application environmental of thedevice under test. An extended bibliography, Section 10, thatprovides information which is useful to test specifiers to assistthem in selecting appropriate test methods is included in thisguide. The b
8、ibliography covers the scope from applicationcondition characterization, single and multiple gas effects, andmaterial and product effects to key application and test vari-ables as well as discussions of atmospheric corrosion pro-cesses.1.4 This standard does not purport to address all of thesafety c
9、oncerns, 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 Sheet for this product/material as pro-vided by the manufacturer, to establish appropriate safety andhea
10、lth practices, and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:B 542 Terminology Relating to Electrical Contacts andTheir Use2B 808 Test Method for Monitoring of Atmospheric Corro-sion Chambers by Quartz Crystal Microbalances2B 810 Test
11、 Method for Calibration of Atmospheric Corro-sion Test Chambers by Change in Mass of Copper Cou-pons2B 825 Test Method for Coulometric Reduction of SurfaceFilms on Metallic Test Samples2B 826 Test Method for Monitoring Atmospheric CorrosionTests by Electrical Resistance Probes2B 827 Practice for Con
12、ducting Mixed Flowing Gas (MFG)Environmental Tests22.2 Other Documents:EIA-364B-TP65 Mixed Industrial Gas Test Procedure3IEC Standard 68-242 Basic Environmental Testing Proce-dures, Test KcSulphur Dioxide Test for Contacts andConnections4IEC Standard 68-243 Basic Environmental Testing Proce-dures, T
13、est KdHydrogen Sulfide Test for Contacts andConnections4IEC Technical Trend Document 68-260 TTD Environmen-tal Testing, Corrosion Tests in Artificial Atmosphere atVery Low Concentration of Polluting Gas(es)4IEC 68-260 (second edition) Environmental TestingPart2: Teststest Ke: Flowing mixed gas corro
14、sion test, 1995IEEE P1156.1 Environmental Specifications for Computer1This guide is under the jurisdiction of ASTM Committee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B2.11 onElectrical Contact Test Methods.Current edition approved June 10, 2003. Published J
15、uly 2003. Originallyapproved in 1993. Last previous edition approved in 1997 as B 845 - 97.2Annual Book of ASTM Standards, Vol 02.04.3Available from Electronic Industries Association (EIA), 2001 PennsylvaniaAve. N.W., Washington, DC 20006-1813.4Available from American National Standards Institute, 1
16、1 W. 42nd St., 13thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Modules (Draft 4 June 10, 1992unapproved)53. Terminology3.1 Terms relevant to this guide are defined in TerminologyB 542 except as noted in
17、the following section.3.2 Other term:3.2.1 mixed flowing gas testa laboratory test conducted inair that flows through a test chamber in which the temperature,relative humidity, concentrations of gaseous pollutants, andother critical variables are carefully defined, monitored andcontrolled.4. Signifi
18、cance 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 contacts in MFG tests is used to assess t
19、he 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 on a supportingsubstrate, reduced coating
20、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 against each other or againsta set of fixed requ
21、irements. 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 to the contact surfaces. These tests canal
22、so 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 has previouslybeen established.4.6 This guid
23、e provides test conditions which are to beapplied in conjunction with Practice B 827 which defines therequired test operation and certification procedures, tolerances,and reporting requirements. Where the test specifier requirescertifications or tolerances different than those provided inPractice B
24、827, the required certifications or tolerances shall bepart of the test specification. Differences from the specifica-tions in Practice B 827 shall be reported in the test reportprovided by the test operator to the test specifier. Specificationof one of the test conditions defined in this document i
25、n theform of a statement such as, “Parts shall be tested in accor-dance with ASTM B 845 Method Z.”, implicitly requires testcondition, Z, applied according to Practice B 827.5. Procedure5.1 Decide upon a test plan appropriate for the contactsbeing evaluated. Consider test parameters such as precondi
26、-tioning, performance measurement and other evaluation tech-niques, 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 literature. The nextsection provides brief
27、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 fromcombustion of high sulfur coal (1). Th
28、e 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 undertest.6.2 Method BMethod B was origin
29、ally 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 vast majority of applications. Typic
30、al 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-sive environments (3,4). Method C m
31、ay 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 cited in the abovediscussion of Metho
32、d 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 afirst step toward a test containing more than one pollutant gas3,4. Typical exposure time is 4, 10 or 21 days depending uponthe specificati
33、on for the product under test.6.6 Method G, H, and KGeneral InformationThesemethods are often called the Battelle Class II, III, and IV Tests6respectively, since they were developed by the Battelle Colum-bus Laboratories after an extensive study of electronic equip-ment operating conditions (5). The
34、 test conditions were theresult of correlation studies between corrosion products andmechanisms, and test and application conditions, in order toobtain a valid estimate of the corrosion response in theexpected electronic service environments. From this study, itwas concluded that most operating or a
35、pplication environments5Available from the Institute of Electrical and Electronic Engineers, Inc., 345 E.47th St., New York, NY 10017.6It was found that the lack of electrical corrosion failure mechanisms in Class Ienvironments made it unnecessary to develop a Class 1 MFG Test.B 845 97 (2003)2for el
36、ectrical connectors and electronic components can becategorized by a limited number of Severity Classes, which canbe simulated, and 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 ar
37、e as follows: Class I is character-ized by formation of oxides on copper coupons and no visibleattack on porous gold plated, nickel 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 copp
38、er coupons. Class III ischaracterized by pore and tarnish creepage corrosion of Au/Ni/Cu coupons and the formation oxides, sulfides and otherunknown corrosion products on copper coupons. Class IV ischaracterized by tarnish creepage on Au/Ni/Cu coupons andcopper coupon corrosion products similar to C
39、lass III exceptthat sulfide presence greatly exceeds oxide presence whereasfor Class III, the oxide presence is equivalent to the 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 offi
40、ces or control rooms that areassociated with light industrial areas or where environmentalcontrols are not operating effectively 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
41、 as connectors) to this test for 1 to3 weeks.76.6.1.2 Method HMethod H accelerates the effects ofBattelle Class III environments. These correspond to manyindustrial and related locations (including many storage areas)where moderate amounts of pollutants are present in poorlycontrolled environments.
42、These might be found nearer toprimary sources of atmospheric pollutant gases or in industrialenvironments where there are a multiplicity of sources forpollutant gases within a region such that all businesses in suchregions are susceptible. Potential failure mechanisms in thistest include severe pore
43、 corrosion and corrosion productmigration from the pores or from the base-metal edges adjoin-ing the gold finish. Heavy film growth on base metals andaccelerated attack on other susceptible materials are alsopossible (5). Typical industry practice has been to expose testhardware (such as connectors)
44、 to this test for 10 or 20 days.87EIA 364 TP-65 designates these test conditions as Environmental Class II (8).8EIA 364 TP-65 designates these test conditions as 8Environmental Class III(8).TABLE 1 Test Conditions of Mixed Flowing Gas TestsASTMMethodH2S ppbASO2ppbACl2ppbANO2ppb Temp. C RH %AirChange
45、s(# /h)Air Velocity(m/h)Duration(days)Source Ref. NotesA 25,0006500025 6 2B756520-60 4, 10, 21 Kc(1)CB 12,5006250025 6 2B75653-5 20-60 4, 10, 21 Kd(2)C 500610025 6 1B75633-5 60 4, 10, 21 KeMethod A(3,4)D 10062025 6 1B756 33-5 60 4, 10, 21 KeMethod B(3,4)E 100620500610025 6 1B75633-10 60 4, 10, 21 Ke
46、IEC 68-2-60TestMethod 1(3,4)G10+0/410+0/2200625306270623-8 BattelleClass II(5,16,17)(8)DH 1006102065200625306275623-8 BattelleClass III(5,16,17)(8)E,FK 2006105065200625506275623-8 BattelleClass IV(5,8)L4065%35065%3615 %61065%3060.570621832 G1(T) (9)M106 5 200 6 20 10 6 5 200 6 20 25 6 1B75 6 3 3-10
47、10, 21 KeIEC 68-2-60(3,4,11)(12)N10+0/42006 2510+ 0/22006 25306 2706 2perASTMB 827perASTMB 8275-30 Telecomcentraloffice(14,15)O106 5 100 6 20 10 6 3 200 6 50 30 6 1706 2 perASTMB 827perASTMB 82710, 20 Telecomcentraloffice(16,17)P 100 6 20 200 6 50 20 6 5 200 6 50 30 6 1706 2 perASTMB 827perASTMB 827
48、20 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 refrigeration in order to assure compliance with specified temperature and humidity variation limits.CCarbon diox
49、ide, 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 corrosion 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.B
