ASTM B845-97(2003)
(Guide)Standard Guide for Mixed Flowing Gas (MFG) Tests for Electrical Contacts
Standard Guide for Mixed Flowing Gas (MFG) Tests for Electrical Contacts
SCOPE
1.1 The techniques described in this guide pertain to mixed flowing gas (MFG) tests containing species that are applied to evaluate devices containing electrical contacts such as slip rings, separable connectors, electromechanical relays or switch contacts. These techniques may be relevant to other devices, but it is the responsibility of the user to determine suitability prior to testing.
1.2 The MFG tests described in this guide are designed to accelerate corrosive degradation processes. These accelerations are designed such that the degradation occurs in a much shorter time period than that expected for such processes in the intended application environment of the device being tested. Application environments can vary continuously from benign to aggressively corrosive. Connectors and contacts within closed electronic cabinets may be affected by an environment of different severity than the environment on the outside of such cabinets. In general, indoor environments are different than outdoor environments. The MFG tests described herein, being discrete embodiments of specific corrosive conditions, cannot be representative of all possible application environments. It is the responsibility of the test specifier to assure the pertinence of a given test condition to the specifier's application condition.
1.3 The MFG tests described herein are not designed to duplicate the actual intended application environmental of the device under test. An extended bibliography, Section 10, that provides information which is useful to test specifiers to assist them in selecting appropriate test methods is included in this guide. The bibliography covers the scope from application condition characterization, single and multiple gas effects, and material and product effects to key application and test variables as well as discussions of atmospheric corrosion processes.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to become familiar with all hazards including those identified in the appropriate Material Safety Data Sheet for this product/material as provided by the manufacturer, to establish appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use.
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Designation:B845–97(Reapproved2003)
Standard Guide for
Mixed Flowing Gas (MFG) Tests for Electrical Contacts
This standard is issued under the fixed designation B 845; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to become familiar
with all hazards including those identified in the appropriate
1.1 The techniques described in this guide pertain to mixed
Material Safety Data Sheet for this product/material as pro-
flowing gas (MFG) tests containing species that are applied to
vided by the manufacturer, to establish appropriate safety and
evaluate devices containing electrical contacts such as slip
health practices, and determine the applicability of regulatory
rings, separable connectors, electromechanical relays or switch
limitations prior to use.
contacts. These techniques may be relevant to other devices,
but it is the responsibility of the user to determine suitability
2. Referenced Documents
prior to testing.
2.1 ASTM Standards:
1.2 The MFG tests described in this guide are designed to
B 542 Terminology Relating to Electrical Contacts and
accelerate corrosive degradation processes. These accelera-
Their Use
tions are designed such that the degradation occurs in a much
B 808 Test Method for Monitoring of Atmospheric Corro-
shorter time period than that expected for such processes in the
sion Chambers by Quartz Crystal Microbalances
intended application environment of the device being tested.
B 810 Test Method for Calibration of Atmospheric Corro-
Application environments can vary continuously from benign
sion Test Chambers by Change in Mass of Copper Cou-
to aggressively corrosive. Connectors and contacts within
pons
closed electronic cabinets may be affected by an environment
B 825 Test Method for Coulometric Reduction of Surface
of different severity than the environment on the outside of
Films on Metallic Test Samples
such cabinets. In general, indoor environments are different
B 826 Test Method for Monitoring Atmospheric Corrosion
than outdoor environments. The MFG tests described herein,
Tests by Electrical Resistance Probes
being discrete embodiments of specific corrosive conditions,
B 827 Practice for Conducting Mixed Flowing Gas (MFG)
cannot be representative of all possible application environ-
Environmental Tests
ments. It is the responsibility of the test specifier to assure the
2.2 Other Documents:
pertinence of a given test condition to the specifier’s applica-
EIA-364B-TP65 Mixed Industrial Gas Test Procedure
tion condition.
IEC Standard 68-2–42 Basic Environmental Testing Proce-
1.3 The MFG tests described herein are not designed to
dures, Test K Sulphur Dioxide Test for Contacts and
c
duplicate the actual intended application environmental of the
Connections
device under test. An extended bibliography, Section 10, that
IEC Standard 68-2–43 Basic Environmental Testing Proce-
provides information which is useful to test specifiers to assist
dures, Test K Hydrogen Sulfide Test for Contacts and
d
them in selecting appropriate test methods is included in this
Connections
guide. The bibliography covers the scope from application
IECTechnicalTrend Document 68-2–60 TTD Environmen-
condition characterization, single and multiple gas effects, and
tal Testing, Corrosion Tests in Artificial Atmosphere at
material and product effects to key application and test vari-
Very Low Concentration of Polluting Gas(es)
ables as well as discussions of atmospheric corrosion pro-
IEC 68-2–60 (second edition) Environmental Testing—Part
cesses.
2: Tests—test Ke: Flowing mixed gas corrosion test, 1995
1.4 This standard does not purport to address all of the
IEEE P1156.1 Environmental Specifications for Computer
safety concerns, if any, associated with its use. It is the
1 2
This guide is under the jurisdiction of ASTM Committee B02 on Nonferrous Annual Book of ASTM Standards, Vol 02.04.
Metals and Alloys and is the direct responsibility of Subcommittee B2.11 on Available from Electronic Industries Association (EIA), 2001 Pennsylvania
Electrical Contact Test Methods. Ave. N.W., Washington, DC 20006-1813.
Current edition approved June 10, 2003. Published July 2003. Originally Available from American National Standards Institute, 11 W. 42nd St., 13th
approved in 1993. Last previous edition approved in 1997 as B 845 - 97. Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B845–97 (2003)
Modules (Draft 4 June 10, 1992—unapproved) 5. Procedure
5.1 Decide upon a test plan appropriate for the contacts
3. Terminology
being evaluated. Consider test parameters such as precondi-
3.1 Terms relevant to this guide are defined in Terminology tioning, performance measurement and other evaluation tech-
B 542 except as noted in the following section. niques, and experimental controls.
3.2 Other term:
5.2 Select a MFG test and exposure length appropriate for
3.2.1 mixed flowing gas test—a laboratory test conducted in the parts being evaluated. Table 1 lists a number of such tests
air that flows through a test chamber in which the temperature,
that have been documented in the technical literature. The next
relative humidity, concentrations of gaseous pollutants, and section provides brief discussions of the origins and intended
other critical variables are carefully defined, monitored and
purpose of each of the methods.
controlled.
6. Abstracts of Methods
4. Significance and Use 6.1 Method A—Method A was originally developed as a
highly accelerated test to stress equipment that might be
4.1 Preservation of a conducting surface on electrical con-
exposed to environments with high levels of air pollution from
tact is vital to the continued functioning of such contacts.
combustion of high sulfur coal (1). The method is included in
Contamination of the surface with insulating layers formed by
this list for completeness. It is generally not considered
corrosion processes is one potential hazard. Laboratory testing
realistic for evaluation of electronic equipment for the vast
of contacts in MFG tests is used to assess the effectiveness of
majority of applications. Typical exposure time is 4, 10 or 21
design features and materials.
days, depending upon the specification for the product under
4.2 MFG tests are used in development studies of processes
test.
and materials for contacts. For example, coupon specimens
6.2 Method B—Method B was originally developed as a
may be exposed to MFG tests to evaluate new contact
European standard, and has largely been replaced by methods
materials, layers of new coating materials on a supporting
with lower levels of sulfur bearing gases (2). The method is
substrate, reduced coating thicknesses, or protective surface
included in this list for completeness. It is generally not
treatments.
considered realistic for evaluation of electronic equipment for
4.3 MFG tests are also employed to test the durability of a
thevastmajorityofapplications.Typicalexposuretimeis4,10
finished product with respect to atmospheric corrosion. For
or 21 days, depending upon the specification for the product
example, finished connectors may be exposed to a MFG test
under test.
and their performances compared against each other or against
6.3 Method C—Method C was developed in Europe as an
a set of fixed requirements. Relays or switch contacts may be
alternative to Method A in response to requests for a less
exposed in the operated and non-operated conditions to com-
aggressive test that would simulate exposures in less aggres-
pare performance.
sive environments (3,4). Method C may simulate the majority
4.4 MFG tests are useful for determining the effectiveness
of usage environments better than MethodA.Typical exposure
of connector housings and shrouds as barriers to ingress of
time is 4, 10 or 21 days depending upon the specification for
atmospheric corrodants to the contact surfaces. These tests can
the product under test.
also be used to assess the screening of the metal-to-metal
6.4 Method D—Method D was developed in Europe as an
contact areas of mated connectors.
alternative to Method B for the same reasons cited in the above
4.5 MFG tests are employed as qualification tests to deter-
discussion of Method C (3,4).Typical exposure time is 4, 10 or
mine connector failure rates in application environments for
21 days, depending upon the specification for the product
which correlation between test and application has previously
under test.
been established.
6.5 Method E—Method E was developed in Europe as a
4.6 This guide provides test conditions which are to be
first step toward a test containing more than one pollutant gas
applied in conjunction with Practice B 827 which defines the
[3,4].Typicalexposuretimeis4,10or21daysdependingupon
required test operation and certification procedures, tolerances,
the specification for the product under test.
and reporting requirements. Where the test specifier requires
6.6 Method G, H, and K—General Information—These
certifications or tolerances different than those provided in
methodsareoftencalledtheBattelleClassII,III,andIVTests
PracticeB 827,therequiredcertificationsortolerancesshallbe
respectively, since they were developed by the Battelle Colum-
part of the test specification. Differences from the specifica-
bus Laboratories after an extensive study of electronic equip-
tions in Practice B 827 shall be reported in the test report
ment operating conditions (5). The test conditions were the
provided by the test operator to the test specifier. Specification
result of correlation studies between corrosion products and
of one of the test conditions defined in this document in the
mechanisms, and test and application conditions, in order to
form of a statement such as, “Parts shall be tested in accor-
obtain a valid estimate of the corrosion response in the
dance with ASTM B 845 Method Z.”, implicitly requires test
expected electronic service environments. From this study, it
condition, Z, applied according to Practice B 827.
wasconcludedthatmostoperatingorapplicationenvironments
5 6
Available from the Institute of Electrical and Electronic Engineers, Inc., 345 E. It was found that the lack of electrical corrosion failure mechanisms in Class I
47th St., New York, NY 10017. environments made it unnecessary to develop a Class 1 MFG Test.
B845–97 (2003)
TABLE 1 Test Conditions of Mixed Flowing Gas Tests
Air
ASTM Air Velocity Duration
A A A
H S ppb SO ppb Cl ppb NO ppb Temp. °C RH % Changes Source Ref. Notes
2 2 2 2
Method (m/h) (days)
(# /h)
B C
A 25,000 25 6 2 75 20-60 4, 10, 21 K (1)
c
65000 65
B
B 12,500 25 6 2 75 3-5 20-60 4, 10, 21 K (2)
d
62500 65
B
C 500 25 6 1 75 3-5 60 4, 10, 21 K (3,4)
e
6100 63 Method A
B
D 100 25 6 1 75 3-5 60 4, 10, 21 K (3,4)
e
620 6 3 Method B
B
E 100 500 25 6 1 75 3-10 60 4, 10, 21 K (3,4)
e
620 6100 63 IEC 68-2-60
Test
Method 1
D
G10 10 200 30 70 3-8 Battelle (5,16,17)
+0/−4 +0/−2 625 62 62 Class II (8)
E,F
H 100 20 200 30 75 3-8 Battelle (5,16,17)
610 65 625 62 62 Class III (8)
K 200 50 200 50 75 3-8 Battelle (5,8)
610 65 625 62 62 Class IV
L40 350 3 610 30 70 1832 G1(T) (9)
65% 65% 615 % 65% 60.5 62
B
M10 6 5 200 6 20 10 6 5 200 6 20 25 6 1 75 6 3 3-10 10, 21 K (3,4,11)
e
IEC 68-2-60 (12)
N10 200 10 200 30 70 per per 5-30 Telecom (14,15)
+0/−4 6 25 + 0/−2 6 25 6 2 6 2 ASTM ASTM central
B 827 B 827 office
O10 6 5 100 6 20 10 6 3 200 6 50 30 6170 6 2 per per 10, 20 Telecom (16,17)
ASTM ASTM central
B 827 B 827 office
P 100 6 20 200 6 50 20 6 5 200 6 50 30 6170 6 2 per per 20 Telecom (16,17)
ASTM ASTM uncontrolled
B 827 B 827 environment
Notes:
A 9
Gas concentrations in ppb refer to parts per billion (1 in 10 ) volume per volume (vol/vol) in air.
B
The test temperature of 25°C may require refrigeration in order to assure compliance with specified temperature and humidity variation limits.
C
Carbon dioxide, 4500 parts per million (vol/vol) maximum.
D
References (16 and 17) show NO level as 100 ppb and temperature as 25°C while reference (5) shows the values in the table above; difference in corrosion of copper
is minor between the two sets of conditions per private communication dated April 26, 1991, W. H. Abbott to E. Sproles.
E
Relative 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.
F
Test conditions are defined in purchase contract.
for electrical connectors and electronic components can be Light tarnish creepage corrosion has been reported to be found
categorizedbyalimitednumberofSeverityClasses,whichcan in Class II gas tests. Typical industry practice has been to
be simulated, and their effects accelerated, by adjusting the expose test hardware (such as connectors) to this test for 1 to
critical parameters of the MFG test. 3 weeks.
6.6.1 The descriptions in reference (5) of operating environ- 6.6.1.2 Method H—Method H accelerates the effects of
ment Classes I through IV are as follows: Class I is character- Battelle Class III environments. These correspond to many
ized by formation of oxides on copper coupons and no visible industrial and related locations (including many storage areas)
attack on porous gold plated, nickel underplated, copper where moderate amounts of pollutants are present in poorly
coupons(Au/Ni/Cu)ClassIIischaracterizedbyporecorrosion controlled environments. These might be found nearer to
of Au/Ni/Cu coupons and formation of oxides and complex primary sources of atmospheric pollutant gases or in industrial
copper hydroxy chlorides on copper coupons. Class III is environments where there are a multiplicity of sources for
characterized by pore and tarnish creepage corrosion of Au/ pollutant gases within a region such that all businesses in such
Ni/Cu coupons and the formation oxides, sulfides and other regions are susceptible. Potential failure mechanisms in this
unknown corrosion products on copper coupons. Class IV is test include severe pore corrosion and corrosion product
characterized by tarnish creepage on Au/Ni/Cu coupons and migration from the pores or from the base-metal edges adjoin-
copper coupon corrosion products similar to Class III except ing the gold finish. Heavy film growth on base metals and
that sulfide presence greatly exceeds oxide presence whereas accelerated attack on other susceptible materials are also
for Class III, the oxide
...
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