ASTM B845-97(2024)
(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
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B845 − 97 (Reapproved 2024)
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
Safety Data Sheet (SDS) for this product/material as provided
rings, separable connectors, electromechanical relays or switch
by the manufacturer, to establish appropriate safety, health,
contacts. These techniques may be relevant to other devices,
and environmental practices, and determine the applicability
but it is the responsibility of the user to determine suitability
of regulatory limitations prior to use.
prior to testing.
1.6 This international standard was developed in accor-
1.2 The MFG tests described in this guide are designed to
dance with internationally recognized principles on standard-
accelerate corrosive degradation processes. These accelera-
ization established in the Decision on Principles for the
tions are designed such that the degradation occurs in a much
Development of International Standards, Guides and Recom-
shorter time period than that expected for such processes in the
mendations issued by the World Trade Organization Technical
intended application environment of the device being tested.
Barriers to Trade (TBT) Committee.
Application environments can vary continuously from benign
to aggressively corrosive. Connectors and contacts within
2. Referenced Documents
closed electronic cabinets may be affected by an environment
2.1 ASTM Standards:
of different severity than the environment on the outside of
B542 Terminology Relating to Electrical Contacts and Their
such cabinets. In general, indoor environments are different
Use
than outdoor environments. The MFG tests described herein,
B808 Test Method for Monitoring of Atmospheric Corrosion
being discrete embodiments of specific corrosive conditions,
Chambers by Quartz Crystal Microbalances
cannot be representative of all possible application environ-
B810 Test Method for Calibration of Atmospheric Corrosion
ments. It is the responsibility of the test specifier to assure the
Test Chambers by Change in Mass of Copper Coupons
pertinence of a given test condition to the specifier’s applica-
B825 Test Method for Coulometric Reduction of Surface
tion condition.
Films on Metallic Test Samples
1.3 The MFG tests described herein are not designed to
B826 Test Method for Monitoring Atmospheric Corrosion
duplicate the actual intended application environment of the
Tests by Electrical Resistance Probes
device under test. An extended bibliography that provides
B827 Practice for Conducting Mixed Flowing Gas (MFG)
information which is useful to test specifiers to assist them in
Environmental Tests
selecting appropriate test methods is included in this guide.
2.2 Other Documents:
The bibliography covers the scope from application condition
EIA-364B-TP65 Mixed Industrial Gas Test Procedure
characterization, single and multiple gas effects, and material
IEC Standard 68-2–42 Basic Environmental Testing
and product effects to key application and test variables as well
Procedures, Test K Sulphur Dioxide Test for Contacts and
c
as discussions of atmospheric corrosion processes.
Connections
1.4 The values stated in SI units are to be regarded as
IEC Standard 68-2–43 Basic Environmental Testing
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 B02.05 on the ASTM website.
Precious Metals and Electrical Contact Materials and Test Methods. Available from IHS, 15 Inverness Way East, Englewood, CO 80112, http://
Current edition approved April 1, 2024. Published April 2024. Originally www.global.ihs.com.
approved in 1993. Last previous edition approved in 2018 as B845 – 97 (2018). Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
DOI: 10.1520/B0845-97R24. 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 (2024)
Procedures, Test K Hydrogen Sulfide Test for Contacts certifications or tolerances different than those provided in
d
and Connections Practice B827, the required certifications or tolerances shall be
IEC Technical Trend Document 68-2–60 TTD Environmen- part of the test specification. Differences from the specifica-
tal Testing, Corrosion Tests in Artificial Atmosphere at tions in Practice B827 shall be reported in the test report
Very Low Concentration of Polluting Gas(es) provided by the test operator to the test specifier. Specification
IEC 68-2–60 (second edition) Environmental Testing—Part of one of the test conditions defined in this document in the
2: Tests—test Ke: Flowing mixed gas corrosion test, 1995 form of a statement such as, “Parts shall be tested in accor-
IEEE P1156.1 Environmental Specifications for Computer dance with ASTM B845 Method Z.”, implicitly requires test
Modules (Draft 4 Approved June 17, 1993.) 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
6. Abstracts of Methods
4.1 Preservation of a conducting surface on electrical con-
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
realistic for evaluation of electronic equipment for the vast
4.2 MFG tests are used in development studies of processes
majority of applications. Typical exposure time is 4, 10 or 21
and materials for contacts. For example, coupon specimens
days, depending upon the specification for the product under
may be exposed to MFG tests to evaluate new contact
test.
materials, layers of new coating materials on a supporting
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
with lower levels of sulfur bearing gases (2). The method is
4.3 MFG tests are also employed to test the durability of a
included in this list for completeness. It is generally not
finished product with respect to atmospheric corrosion. For
considered realistic for evaluation of electronic equipment for
example, finished connectors may be exposed to a MFG test
the vast majority of applications. Typical exposure time is 4, 10
and their performances compared against each other or against
or 21 days, depending upon the specification for the product
a set of fixed requirements. Relays or switch contacts may be
under test.
exposed in the operated and non-operated conditions to com-
pare performance.
6.3 Method C—Method C was developed in Europe as an
alternative to Method A in response to requests for a less
4.4 MFG tests are useful for determining the effectiveness
aggressive test that would simulate exposures in less aggres-
of connector housings and shrouds as barriers to ingress of
sive environments (3,4). Method C may simulate the majority
atmospheric corrodants to the contact surfaces. These tests can
of usage environments better than Method A. Typical exposure
also be used to assess the screening of the metal-to-metal
time is 4, 10 or 21 days depending upon the specification for
contact areas of mated connectors.
the product under test.
4.5 MFG tests are employed as qualification tests to deter-
6.4 Method D—Method D was developed in Europe as an
mine connector failure rates in application environments for
alternative to Method B for the same reasons cited in the above
which correlation between test and application has previously
discussion of Method C (3,4). Typical exposure time is 4, 10 or
been established.
21 days, depending upon the specification for the product
4.6 This guide provides test conditions which are to be
under test.
applied in conjunction with Practice B827 which defines the
6.5 Method E—Method E was developed in Europe as a first
required test operation and certification procedures, tolerances,
step toward a test containing more than one pollutant gas (3,4).
and reporting requirements. Where the test specifier requires
5 6
Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE), The boldface numbers in parentheses refer to a list of references at the end of
445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http://www.ieee.org. this guide.
B845 − 97 (2024)
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
G 10 10 200 30 70 3-8 Battelle (5,6,7)
D
+0/−4 +0/−2 ±25 ±2 ±2 Class II (8)
H 100 20 200 30 75 3-8 Battelle (5,6,7)
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
L 40 350 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 (3,4,10)
e
IEC 68-2-60 (11)
N 10 200 10 200 30 70 in in accor- 5-30 Telecom (12,13)
+0/−4 ± 25 + 0/−2 ± 25 ± 2 ± 2 accordance dance with central
with ASTM office
ASTM B827
B827
O 10 ± 5 100 ± 20 10 ± 3 200 ± 50 30 ± 1 70 ± 2 in accor- in accor- 10, 20 Telecom (6,7)
dance with dance with central
ASTM ASTM office
B827 B827
P 100 ± 20 200 ± 50 20 ± 5 200 ± 50 30 ± 1 70 ± 2 in accor- in accor- 20 Telecom (6,7)
dance with dance with uncontrolled
ASTM ASTM environment
B827 B827
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 (6 and 7) 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 (6 and 7)) 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.
Typical exposure time is 4, 10 or 21 days depending upon the 6.6.1 The descriptions in reference (5) of operating environ-
specification for the product under test.
ment Classes I through IV are as follows: Class I is character-
ized by formation of oxides on copper coupons and no visible
6.6 Method G, H, and K—General Information—These
attack on porous gold plated, nickel underplated, copper
methods are often called the Battelle Class II, III, and IV Tests
coupons (Au/Ni/Cu). Class II is characterized by pore corro-
respectively, since they were developed by the Battelle Colum-
sion of Au/Ni/Cu coupons and formation of oxides and
bus Laboratories after an extensive study of electronic equip-
complex copper hydroxy chlorides on copper coupons. Class
ment operating conditions (5). The test conditions were the
result of correlation studies between corrosion products and III is characterized by pore and tarnish creepage corrosion of
Au/Ni/Cu coupons and the formation of oxides, sulfides, and
mechanisms, and test and application conditions, in order to
obtain a valid estimate of the corrosion response in the other unknown corrosion products on copper coupons. Class
expected electronic service environments. From this study, it IV is characterized by tarnish creepage on Au/Ni/Cu coupons
was concluded that most operating or application environments
and copper coupon corrosion products similar to Class III,
for electrical connectors and electronic components can be
except that sulfide presence greatly exceeds oxide presence
categorized by a limited number of Severity Classes, which can
whereas for Class III the oxide presence is equivalent to the
be simulated, and the
...
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