ASTM B845-97
(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 corrosive 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, 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 establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: B 845 – 97
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 2. Referenced Documents
1.1 The techniques described in this guide pertain to mixed 2.1 ASTM Standards:
flowing gas (MFG) tests containing species that are applied to B 542 Terminology Relating to Electrical Contacts and
evaluate devices containing electrical contacts such as slip Their Use
rings, separable connectors, electromechanical relays or switch B 808 Test Method for Monitoring of Atmospheric Corro-
contacts. These techniques may be relevant to other devices, sion Chambers by Quartz Crystal Microbalances
but it is the responsibility of the user to determine suitability B 810 Test Method for Calibration of Atmospheric Corro-
prior to testing. sion Test Chambers by Change in Mass of Copper Cou-
1.2 The MFG tests described in this guide are designed to pons
accelerate corrosive degradation processes. These accelera- B 825 Test Method for Coulometric Reduction of Surface
tions are designed such that the degradation occurs in a much Films on Metallic Test Samples
shorter time period than that expected for such processes in the B 826 Test Method for Monitoring Atmospheric Corrosion
intended application environment of the device being tested. Tests by Electrical Resistance Probes
Application environments can vary continuously from benign B 827 Practice for Conducting Mixed Flowing Gas (MFG)
to aggressively corrosive. Connectors and contacts within Environmental Tests
closed electronic cabinets may be affected by an environment 2.2 Other Documents:
of different severity than the environment on the outside of EIA-364B-TP65 Mixed Industrial Gas Test Procedure
such cabinets. In general, indoor environments are different IEC Standard 68-2–42 Basic Environmental Testing Proce-
than outdoor environments. The MFG tests described herein, dures, Test K Sulphur Dioxide Test for Contacts and
c
being discrete embodiments of specific corrosive conditions, Connections
cannot be representative of all possible application environ- IEC Standard 68-2–43 Basic Environmental Testing Proce-
ments. It is the responsibility of the test specifier to assure the dures, Test K Hydrogen Sulfide Test for Contacts and
d
pertinence of a given test condition to the specifier’s applica- Connections
tion condition. IEC Technical Trend Document 68-2–60 TTD Environmen-
1.3 The MFG tests described herein are not designed to tal Testing, Corrosion Tests in Artificial Atmosphere at
duplicate the actual intended application environmental of the Very Low Concentration of Polluting Gas(es)
device under test. An extended bibliography, Section 10, that IEC 68-2–60 (second edition) Environmental Testing—Part
provides information which is useful to test specifiers to assist 2: Tests—test Ke: Flowing mixed gas corrosion test, 1995
them in selecting appropriate test methods is included in this IEEE P1156.1 Environmental Specifications for Computer
guide. The bibliography covers the scope from application Modules (Draft 4 June 10, 1992—unapproved)
condition characterization, single and multiple gas effects, and
3. Terminology
material and product effects to key application and test vari-
3.1 Terms relevant to this guide are defined in Terminology
ables as well as discussions of atmospheric corrosion pro-
cesses. B 542 except as noted in the following section.
3.2 Other term:
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.2.1 mixed flowing gas test—a laboratory test conducted in
air that flows through a test chamber in which the temperature,
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
Annual Book of ASTM Standards, Vol 03.04.
Available from Electronic Industries Association (EIA), 2001 Pennsylvania
Ave. N.W., Washington, DC 20006-1813.
1 4
This guide is under the jurisdiction of ASTM Committee B-2 on Nonferrous Available from American National Standards Institute, 11 W. 42nd St., 13th
Metals and Alloys and is the direct responsibility of Subcommittee B2.11 on Floor, New York, NY 10036.
Electrical Contact Test Methods. Available from the Institute of Electrical and Electronic Engineers, Inc., 345 E.
Current edition approved May 10, 1997. Published December 1997. 47th St., New York, NY 10017.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
B 845
relative humidity, concentrations of gaseous pollutants, and highly accelerated test to stress equipment that might be
other critical variables are carefully defined, monitored and exposed to environments with high levels of air pollution from
controlled. combustion of high sulfur coal (1). The method is included in
this list for completeness. It is generally not considered
4. Significance and Use
realistic for evaluation of electronic equipment for the vast
4.1 Preservation of a conducting surface on electrical con-
majority of applications. Typical exposure time is 4, 10 or 21
tact is vital to the continued functioning of such contacts.
days, depending upon the specification for the product under
Contamination of the surface with insulating layers formed by
test.
corrosion processes is one potential hazard. Laboratory testing
6.2 Method B—Method B was originally developed as a
of contacts in MFG tests is used to assess the effectiveness of
European standard, and has largely been replaced by methods
design features and materials.
with lower levels of sulfur bearing gases (2). The method is
4.2 MFG tests are used in development studies of processes
included in this list for completeness. It is generally not
and materials for contacts. For example, coupon specimens
considered realistic for evaluation of electronic equipment for
may be exposed to MFG tests to evaluate new contact
the vast majority of applications. Typical exposure time is 4, 10
materials, layers of new coating materials on a supporting
or 21 days, depending upon the specification for the product
substrate, reduced coating thicknesses, or protective surface
under test.
treatments.
6.3 Method C—Method C was developed in Europe as an
4.3 MFG tests are also employed to test the durability of a
alternative to Method A in response to requests for a less
finished product with respect to atmospheric corrosion. For
aggressive test that would simulate exposures in less aggres-
example, finished connectors may be exposed to a MFG test
sive environments (3,4). Method C may simulate the majority
and their performances compared against each other or against
of usage environments better than Method A. Typical exposure
a set of fixed requirements. Relays or switch contacts may be
time is 4, 10 or 21 days depending upon the specification for
exposed in the operated and non-operated conditions to com-
the product under test.
pare performance.
6.4 Method D—Method D was developed in Europe as an
4.4 MFG tests are useful for determining the effectiveness
alternative to Method B for the same reasons cited in the above
of connector housings and shrouds as barriers to ingress of
discussion of Method C (3,4). Typical exposure time is 4, 10 or
atmospheric corrodants to the contact surfaces. These tests can
21 days, depending upon the specification for the product
also be used to assess the screening of the metal-to-metal
under test.
contact areas of mated connectors.
6.5 Method E—Method E was developed in Europe as a
4.5 MFG tests are employed as qualification tests to deter-
first step toward a test containing more than one pollutant gas
mine connector failure rates in application environments for
[3,4]. Typical exposure time is 4, 10 or 21 days depending upon
which correlation between test and application has previously
the specification for the product under test.
been established.
6.6 Method G, H, and K—General Information—These
4.6 This guide provides test conditions which are to be
methods are often called the Battelle Class II, III, and IV Tests
applied in conjunction with Practice B 827 which defines the
respectively, since they were developed by the Battelle Colum-
required test operation and certification procedures, tolerances,
bus Laboratories after an extensive study of electronic equip-
and reporting requirements. Where the test specifier requires
ment operating conditions (5). The test conditions were the
certifications or tolerances different than those provided in
result of correlation studies between corrosion products and
Practice B 827, the required certifications or tolerances shall be
mechanisms, and test and application conditions, in order to
part of the test specification. Differences from the specifica-
obtain a valid estimate of the corrosion response in the
tions in Practice B 827 shall be reported in the test report
expected electronic service environments. From this study, it
provided by the test operator to the test specifier. Specification
was concluded that most operating or application environments
of one of the test conditions defined in this document in the
for electrical connectors and electronic components can be
form of a statement such as, “Parts shall be tested in accor-
categorized by a limited number of Severity Classes, which can
dance with ASTM B 845 Method Z.”, implicitly requires test
be simulated, and their effects accelerated, by adjusting the
condition, Z, applied according to Practice B 827.
critical parameters of the MFG test.
5. Procedure 6.6.1 The descriptions in reference (5) of operating environ-
ment Classes I through IV are as follows: Class I is character-
5.1 Decide upon a test plan appropriate for the contacts
ized by formation of oxides on copper coupons and no visible
being evaluated. Consider test parameters such as precondi-
attack on porous gold plated, nickel underplated, copper
tioning, performance measurement and other evaluation tech-
coupons (Au/Ni/Cu) Class II is characterized by pore corrosion
niques, and experimental controls.
of Au/Ni/Cu coupons and formation of oxides and complex
5.2 Select a MFG test and exposure length appropriate for
copper hydroxy chlorides on copper coupons. Class III is
the parts being evaluated. Table 1 lists a number of such tests
characterized by pore and tarnish creepage corrosion of Au/
that have been documented in the technical literature. The next
Ni/Cu coupons and the formation oxides, sulfides and other
section provides brief discussions of the origins and intended
purpose of each of the methods.
6. Abstracts of Methods
It was found that the lack of electrical corrosion failure mechanisms in Class I
6.1 Method A—Method A was originally developed as a environments made it unnecessary to develop a Class 1 MFG Test.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
B 845
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.
unknown corrosion products on copper coupons. Class IV is environments where there are a multiplicity of sources for
characterized by tarnish creepage on Au/Ni/Cu coupons and pollutant gases within a region such that all businesses in such
copper coupon corrosion products similar to Class III except regions are susceptible. Potential failure mechanisms in this
that sulfide presence greatly exceeds oxide presence whereas test include severe pore corrosion and corrosion product
for Class III, the oxide presence is equivalent to the sulfide migration from the pores or from the base-metal edges adjoin-
presence (5). ing the gold finish. Heavy film growth on base metals and
6.6.1.1 Method G—Method G accelerates the effects of accelerated attack on other susceptible materials are also
Battelle Class II environments. These correspond to conditions possible (5). Typical industry practice has been to expose test
that are often found in business offices or control rooms that are hardware (such as connectors) to this test for 10 or 20 days.
associated with light industrial areas or where environm
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.