ASTM B845-97(2013)
(Guide)Standard Guide for Mixed Flowing Gas (MFG) Tests for Electrical Contacts
Standard Guide for Mixed Flowing Gas (MFG) Tests for Electrical Contacts
SIGNIFICANCE AND USE
4.1 Preservation of a conducting surface on electrical contact is vital to the continued functioning of such contacts. Contamination of the surface with insulating layers formed by corrosion processes is one potential hazard. Laboratory testing of contacts in MFG tests is used to assess the effectiveness of design features and materials.
4.2 MFG tests are used in development studies of processes and materials for contacts. For example, coupon specimens may be exposed to MFG tests to evaluate new contact materials, layers of new coating materials on a supporting substrate, reduced coating thicknesses, or protective surface treatments.
4.3 MFG tests are also employed to test the durability of a finished product with respect to atmospheric corrosion. For example, finished connectors may be exposed to a MFG test and their performances compared against each other or against a set of fixed requirements. Relays or switch contacts may be exposed in the operated and non-operated conditions to compare performance.
4.4 MFG tests are useful for determining the effectiveness of connector housings and shrouds as barriers to ingress of atmospheric corrodants to the contact surfaces. These tests can also be used to assess the screening of the metal-to-metal contact areas of mated connectors.
4.5 MFG tests are employed as qualification tests to determine connector failure rates in application environments for which correlation between test and application has previously been established.
4.6 This guide provides test conditions which are to be applied in conjunction with Practice B827 which defines the required test operation and certification procedures, tolerances, and reporting requirements. Where the test specifier requires certifications or tolerances different than those provided in Practice B827, the required certifications or tolerances shall be part of the test specification. Differences from the specifications in Practice B827 shall be reported in the test re...
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 environment of the device under test. An extended bibliography 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 The values stated in SI units are to be regarded as standard. No other uni...
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B845 − 97(Reapproved 2013)
Standard Guide for
Mixed Flowing Gas (MFG) Tests for Electrical Contacts
This standard is issued under the fixed designation B845; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 The techniques described in this guide pertain to mixed
responsibility of the user of this standard to become familiar
flowing gas (MFG) tests containing species that are applied to
with all hazards including those identified in the appropriate
evaluate devices containing electrical contacts such as slip
Material Safety Data Sheet (MSDS) for this product/material
rings, separable connectors, electromechanical relays or switch
as provided by the manufacturer, to establish appropriate
contacts. These techniques may be relevant to other devices,
safety and health practices, and determine the applicability of
but it is the responsibility of the user to determine suitability
regulatory limitations prior to use.
prior to testing.
1.2 The MFG tests described in this guide are designed to
2. Referenced Documents
accelerate corrosive degradation processes. These accelera-
2.1 ASTM Standards:
tions are designed such that the degradation occurs in a much
B542 Terminology Relating to Electrical Contacts and Their
shorter time period than that expected for such processes in the
Use
intended application environment of the device being tested.
B808 TestMethodforMonitoringofAtmosphericCorrosion
Application environments can vary continuously from benign
Chambers by Quartz Crystal Microbalances
to aggressively corrosive. Connectors and contacts within
B810 Test Method for Calibration ofAtmospheric Corrosion
closed electronic cabinets may be affected by an environment
Test Chambers by Change in Mass of Copper Coupons
of different severity than the environment on the outside of
B825 Test Method for Coulometric Reduction of Surface
such cabinets. In general, indoor environments are different
Films on Metallic Test Samples
than outdoor environments. The MFG tests described herein,
B826 Test Method for Monitoring Atmospheric Corrosion
being discrete embodiments of specific corrosive conditions,
Tests by Electrical Resistance Probes
cannot be representative of all possible application environ-
B827 Practice for Conducting Mixed Flowing Gas (MFG)
ments. It is the responsibility of the test specifier to assure the
Environmental Tests
pertinence of a given test condition to the specifier’s applica-
2.2 Other Documents:
tion condition.
EIA-364B-TP65 Mixed Industrial Gas Test Procedure
1.3 The MFG tests described herein are not designed to
IEC Standard 68-2–42 Basic Environmental Testing
duplicate the actual intended application environment of the
Procedures,TestK SulphurDioxideTestforContactsand
c
device under test. An extended bibliography that provides
Connections
information which is useful to test specifiers to assist them in
IEC Standard 68-2–43 Basic Environmental Testing
selecting appropriate test methods is included in this guide.
Procedures, Test K Hydrogen Sulfide Test for Contacts
d
The bibliography covers the scope from application condition
and Connections
characterization, single and multiple gas effects, and material
IEC Technical Trend Document 68-2–60 TTD Environmen-
and product effects to key application and test variables as well
tal Testing, Corrosion Tests in Artificial Atmosphere at
as discussions of atmospheric corrosion processes.
Very Low Concentration of Polluting Gas(es)
IEC 68-2–60 (second edition) Environmental Testing—Part
1.4 The values stated in SI units are to be regarded as
2: Tests—test Ke: Flowing mixed gas corrosion test, 1995
standard. No other units of measurement are included in this
standard.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
This guide is under the jurisdiction of ASTM Committee B02 on Nonferrous Standards volume information, refer to the standard’s Document Summary page on
Metals and Alloys and is the direct responsibility of Subcommittee B02.11 on the ASTM website.
Electrical Contact Test Methods. Available from Electronic Industries Alliance (EIA), 2500 Wilson Blvd.,
Current edition approved Aug. 1, 2013. Published August 2013. Originally Arlington, VA 22201, http://www.eia.org.
ε2 4
approved in 1993. Last previous edition approved in 2008 as B845 – 97 (2008) . Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
DOI: 10.1520/B0845-97R13. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B845 − 97 (2013)
IEEE P1156.1 Environmental Specifications for Computer dance with ASTM B845 Method Z.”, implicitly requires test
Modules (Draft 4 June 10, 1992—unapproved) condition, Z, applied according to Practice B827.
3. Terminology
5. Procedure
3.1 Terms relevant to this guide are defined in Terminology
5.1 Decide upon a test plan appropriate for the contacts
B542 except as noted in the following section.
being evaluated. Consider test parameters such as
preconditioning, performance measurement and other evalua-
3.2 Other term:
tion techniques, and experimental controls.
3.2.1 mixed flowing gas test, n—a laboratory test conducted
in air that flows through a test chamber in which the
5.2 Select a MFG test and exposure length appropriate for
temperature, relative humidity, concentrations of gaseous
the parts being evaluated. Table 1 lists a number of such tests
pollutants, and other critical variables are carefully defined,
that have been documented in the technical literature.The next
monitored and controlled.
section provides brief discussions of the origins and intended
purpose of each of the methods.
4. Significance and Use
4.1 Preservation of a conducting surface on electrical con-
6. Abstracts of Methods
tact is vital to the continued functioning of such contacts.
6.1 Method A—Method A was originally developed as a
Contamination of the surface with insulating layers formed by
highly accelerated test to stress equipment that might be
corrosion processes is one potential hazard. Laboratory testing
exposed to environments with high levels of air pollution from
of contacts in MFG tests is used to assess the effectiveness of
combustion of high sulfur coal (1). The method is included in
design features and materials.
this list for completeness. It is generally not considered
4.2 MFG tests are used in development studies of processes
realistic for evaluation of electronic equipment for the vast
and materials for contacts. For example, coupon specimens
majority of applications. Typical exposure time is 4, 10 or 21
may be exposed to MFG tests to evaluate new contact
days, depending upon the specification for the product under
materials, layers of new coating materials on a supporting
test.
substrate, reduced coating thicknesses, or protective surface
6.2 Method B—Method B was originally developed as a
treatments.
European standard, and has largely been replaced by methods
4.3 MFG tests are also employed to test the durability of a
with lower levels of sulfur bearing gases (2). The method is
finished product with respect to atmospheric corrosion. For
included in this list for completeness. It is generally not
example, finished connectors may be exposed to a MFG test
considered realistic for evaluation of electronic equipment for
and their performances compared against each other or against
thevastmajorityofapplications.Typicalexposuretimeis4,10
a set of fixed requirements. Relays or switch contacts may be
or 21 days, depending upon the specification for the product
exposed in the operated and non-operated conditions to com-
under test.
pare performance.
6.3 Method C—Method C was developed in Europe as an
4.4 MFG tests are useful for determining the effectiveness
alternative to Method A in response to requests for a less
of connector housings and shrouds as barriers to ingress of
aggressive test that would simulate exposures in less aggres-
atmospheric corrodants to the contact surfaces. These tests can
sive environments (3,4). Method C may simulate the majority
also be used to assess the screening of the metal-to-metal
of usage environments better than MethodA.Typical exposure
contact areas of mated connectors.
time is 4, 10 or 21 days depending upon the specification for
the product under test.
4.5 MFG tests are employed as qualification tests to deter-
mine connector failure rates in application environments for
6.4 Method D—Method D was developed in Europe as an
which correlation between test and application has previously
alternative to Method B for the same reasons cited in the above
been established.
discussion of Method C (3,4).Typical exposure time is 4, 10 or
21 days, depending upon the specification for the product
4.6 This guide provides test conditions which are to be
applied in conjunction with Practice B827 which defines the under test.
required test operation and certification procedures, tolerances,
6.5 MethodE—MethodEwasdevelopedinEuropeasafirst
and reporting requirements. Where the test specifier requires
step toward a test containing more than one pollutant gas (3,4).
certifications or tolerances different than those provided in
Typical exposure time is 4, 10 or 21 days depending upon the
Practice B827, the required certifications or tolerances shall be
specification for the product under test.
part of the test specification. Differences from the specifica-
6.6 Method G, H, and K—General Information—These
tions in Practice B827 shall be reported in the test report
methodsareoftencalledtheBattelleClassII,III,andIVTests
provided by the test operator to the test specifier. Specification
of one of the test conditions defined in this document in the
form of a statement such as, “Parts shall be tested in accor-
The boldface numbers in parentheses refer to a list of references at the end of
this guide.
5 7
Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE), It was found that the lack of electrical corrosion failure mechanisms in Class I
445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http://www.ieee.org. environments made it unnecessary to develop a Class 1 MFG Test.
B845 − 97 (2013)
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
A 25,000 25±2 75 20-60 4, 10, 21 K (1)
c C
±5000 ±5
B
B 12,500 25±2 75 3-5 20-60 4, 10, 21 K (2)
d
±2500 ±5
B
C 500 25±1 75 3-5 60 4, 10, 21 K (3,4)
e
±100 ±3 Method A
B
D 100 25±1 75 3-5 60 4, 10, 21 K (3,4)
e
±20 ±3 Method B
B
E 100 500 25±1 75 3-10 60 4, 10, 21 K (3,4)
e
±20 ±100 ±3 IEC 68-2-60
Test
Method 1
G10 10 200 30 70 3-8 Battelle (5,16,17)
D
+0/−4 +0/−2 ±25 ±2 ±2 Class II (8)
H 100 20 200 30 75 3-8 Battelle (5,16,17)
E,F
±10 ±5 ±25 ±2 ±2 Class III (8)
K 200 50 200 50 75 3-8 Battelle (5,8)
±10 ±5 ±25 ±2 ±2 Class IV
L40 350 3 610 30 70 1832 G1(T) (9)
±5 % ±5 % ±15 % ±5 % ±0.5 ±2
B
M 10±5 200±20 10±5 200±20 25±1 75 ± 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 ±25 + 0/−2 ±25 ±2 ±2 ASTM ASTM central
B827 B827 office
O 10±5 100±20 10±3 200±50 30±1 70±2 per per 10, 20 Telecom (16,17)
ASTM ASTM central
B827 B827 office
P 100±20 200±50 20±5 200±50 30±1 70±2 per per 20 Telecom (16,17)
ASTM ASTM uncontrolled
B827 B827 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.
respectively, since they were developed by the Battelle Colum- copper coupon corrosion products similar to Class III except
bus Laboratories after an extensive study of electronic equip- that sulfide presence greatly exceeds oxide presence whereas
ment operating conditions (5). The test conditions were the for Class III, the oxide presence is equivalent to the sulfide
result of correlation studies between corrosion products and presence (5).
mechanisms, and test and application conditions, in order to 6.6.1.1 Method G—Method G accelerates the effects of
obtain a valid estimate of the corrosion response in the Battelle Class II environments. These correspond to conditions
expected electronic service environments. From this study, it thatareoftenfoundinbusinessofficesorcontrolroomsthatare
wasconcludedthatmostoperatingorapplicationenvironments associated with light industrial areas or where environmental
for electrical connectors and electronic components can be controls are not operating effectively and continuously (5,6).
categorizedbyalimitednumberofSeverityClasses,whichcan Light tarnish creepage corrosion has been reported to be found
be simulated, and their effects accelerated, by adjusting the in Class II gas tests. Typical industry practice has been to
critical parameters of the MFG test. expose test hardware (such as connectors) to this test for 1 to
6.6.1 The descriptions in reference (5) of operating environ- 3 weeks.
ment Classes I through IV are as follows: Class I is character- 6.6.1.2 Method H—Method H accelerates the effects of
ized by formation of oxides on copper coupons and no visible Battelle Class III environments. These correspond to many
attack on porous gold plated, nickel underplated, copper industrial and related locations (including many storage areas)
coupons(Au/Ni/Cu)ClassIIischaracterizedbyporecorrosion where moderate amounts of pollutants are present in poorly
of Au/Ni/Cu coupons and formation of oxides and complex controlled environments. These might
...
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