Mixed Flowing Gas Testing Introduction and CALCE MFG Capability
Mixed Flowing Gas (MFG) test is a laboratory test in which the temperature (ºC), relative humidity (%RH), concentration of gaous pollutants (ppb level), and other critical variables (such as volume exchange rate and airflow rate) are carefully defined, monitored and controlled. The purpo of this test is to simulate corrosion phenomenon due to atmospheric exposure [1].
潘金莲武松Test samples that have been expod to MFG testing have ranged from bare metal surfaces, to electrical connectors, and to complete asmblies. In regards to noble metal plated connector applications, MFG testing has been widely accepted as a qualification test method to evaluate the performance of the connectors.
In the 1980’s, rearchers at Battelle Labs (Columbus, OH), Telcordia (previously Bellcore), and IBM, carried out tests on the u of MFG to accelerate atmospheric corrosion and its effect on electronic applications. In early 1990’s, professional organizations, including American Society for Testing and Material (ASTM), Electronic Industries Association (EIA), International Electrotechnical Commission (IEC), and Telcordia, began to standardize the test methods and published corresponding documents as guidelines. Among them, ASTM provided the most comprehensive list of documents, covering almost every aspect to perform a well-controlled MFG testing. The documents included:
ASTM B827-97—Standard Practice for Conducting Mixed Flowing Gas Environmental Tests
ASTM B845-97—Standard Guide for Mixed Flowing Gas Tests for Electrical Contacts
ASTM B810-01a—Standard Method for Calibration of Atmospheric Corrosion Test Chambers by Change in Mass of Copper Coupons
ASTM B825-97—Standard Test Method for Coulometric Reduction of Surface Films on Metallic Test Samples ASTM B826-97—Standard Test Method for Monitoring Corrosion Tests by Electrical Resistance Probes
ASTM B808-97—Standard Test Method for Monitoring of Atmospheric Corrosion Chambers by Quartz Crystal Microbalances
The nature of ASTM is to publish voluntary connsus standards for materials, products, systems, and rvices. Therefore, ASTM standards are more likely a review of existing
MFG practices, rather than a mandatory procedure for individual situations. For industrial applications, Battelle Labs MFG Test Methods [2], EIA-364-TP65A [3], IEC 68-2-60 Part 2 [4], and Telcordia GR-63-CORE ction 5.5 Indoor/Outdoor MFG Test Methods [5], are more specific and ap
plication-oriented. Each MFG test method is reviewed below.
To make things clear, it is necessary to understand the background or the industrial coverage of the above-mentioned organization. ASTM International, which grows from US industry, is a non-profit organization that provides a global forum for the development and publication of voluntary connsus standards for materials, products, systems, and rvices [6]. The Electronic Industries Alliance (EIA) is a US national trade organization that includes the full spectrum of U.S. electronic products manufacturers [7]. The International Electrotechnical Commission (IEC), primarily bad on European electronic industry, is the international standards and conformity asssment body for all electrical, electronic and related technologies [8].
Battelle Labs MFG Test Methods
The classification and parameters for the Battelle Labs MFG Test Methods are listed in Table 1. The operational environments for electronic equipments in atmosphere are divided into four class, from least corrosive (Class I) to most corrosive (Class IV). Class I means well-controlled office environment with continuous adjustment. Class II means light industrial environment, such as business offices without effective or continuous environment control. Class III means moderate indus
trial environment, such as storage areas with poor environment control. Class IV means heavy industrial environment, such as locations adjacent to primary sources of atmospheric pollutant gas.
Since available data for Class I indicate no precedent for environmental effects on reliability, there is no accelerated testing for Class I. The other three class u a combination of three corrosive gas, NO2, HS2, Cl2, to accelerate corrosion. Most other standards also u a fourth gas SO2. The reason is that some rearchers believe that H2S
and SO2 have the synergistic effects on metal corrosion and SO2 is necessary to stress nickel in corrosive environments [9].
Table 1: MFG Test Methods Developed by Battelle Labs
香姜Class Temp (ºC) RH (%) H2S (ppb) Cl2 (ppb) NO2 (ppb)
I ---- ---- ---- ---- ----
II 30±2 70±2 10+0/-4 10+0/-2 200±25 III 30±2 75±2 100±10 20±5 200±25 IV 50±2 75±2 200±10 50±5 200±25
Since mixed flowing gas environment is an accelerated testing method, the determination of acceleration factor would be helpful to understand the durability or reliability of “device-under-test”. In another words, if samples can survive certain days in the testing chamber, it will be great to approximately estimate how many years it can last without corrosion problem in the field. Until now, there is no connsus over this factor in a typical mixed flowing gas testing process. However, particular to Battelle classified environment, an acceleration factor of 2 days in the chamber for 1 year in the field was mentioned [10].范曾
EIA MFG Test Methods: EIA-364-TP65A
朋友用英语怎么读EIA published its own specifications for MFG testing as en in Table 2. The latest version was approved on Nov 6, 1997. Class II, III and IV p arameters come directly from Battelle rearch. Class IIA and IIIA are adaptation to Class II and III by adding SO2 along with the other three corrosive gas.
Table 2: MFG Test Methods Developed by EIA
Class Temp (ºC) RH (%) H2S (ppb) Cl2 (ppb) NO2 (ppb) SO2 (ppb)
I ---- ---- ---- ---- ---- ----
II 30±2 70±2 10±5 10±3 200±50 ---- IIA 30±1 70±2 10±5 10±3 200±50 100±20 III 30±2 75±2 100±20 20±5 200±50 ---- IIIA 30±1 70±2 100±20 20±5 200±50 200±50 IV 40±2 75±2 200±20 30±5 200±50 ----
IEC MFG Test Methods: IEC 68-2-60 Part 2
The latest version of IEC 68-2-60 Part 2 about MFG testing was published in Dec 1995. Table 3 shows the parameters for MFG testing by IEC 68-2-60. Test method 1 can be ud as a pore corrosion test on gold coatings. Test method 1 is for testing of contacts with gold-plated surfaces to be ud in mild environments. Methods 2 and 4 are appropriate for electronic products to be ud in moderate corrosive environments. Such environments may be found in telecommunication centers, most office environments and some industrial instrument rooms. Test method 3 is appropriate for more corrosive environments. Such environments may be found in some industrial locations.
Table 3: MFG Test Methods Developed by IEC
Method Temp (ºC) RH (%) H2S (ppb) Cl2 (ppb) NO2 (ppb) SO2 (ppb)
1 25±1 75±3 100±20 ---- ---- 500±100
2 30±1 70±
3 10±5 10±5 200±50 ----
3 30±1 75±3 100±20 20±5 200±50 ----
4 25±1 75±3 10±曹雪芹是男的女的
5 10±5 200±20 200±20
Telcordia MFG Test Methods: Telcordia GR-63-CORE Section 5.5
Telcordia, previously known as Bellcore, is a center for technological experti and innovation that provides the driving force for standardization within the tele-communication industry. Bad on this nature, the MFG test methods developed by Telcordia focus on electronic equipment in Telecommunication applications. Since the kinds of equipments may operate inside or outside the room, two MFG test methods are available from Telcordia, which are known as indoor and outdoor. The parameters for the two methods are listed in Table 4.
Table 4: MFG Test Methods Developed by Telcordia
Method Temp (ºC) RH (%) H2S (ppb) Cl2 (ppb) NO2 (ppb) SO2 (ppb) Indoor 30±1 70±2 10±1.5 10±1.5 200±30 100±15 Outdoor 30±1 70±2 100±15 20±3 200±30 200±30
IBM MFG Test Methods: G1(T)
IBM has worked on accelerated corrosive gas testing extensively since the late 1960’s. They divided the working conditions for electrical equipments into three class, which are G1 (business office), G2 (industrial) and G3 (harsh industrial). In order to simulate the accelerated corrosive effect of equipment in G1 environment, IBM designed and verified the G1 (T) MFG test environment, where they ud four corrosive gas. Unlike other test methods, IBM’s recommended gas concentrations are very different from that of Battelle (e Table 5) [11]. As far as we know, the IBM MFG test method does n ot gain much popularity in the industry. In the last 10 years, almost no paper is available concerning or citing the application of IBM G1(T) method.
Table 5 G1(T) MFG Test Method Developed by IBM
Temp (ºC) RH (%) H2S (ppb) Cl2 (ppb) NO2 (ppb) SO2 (ppb) 30±0.5 70±2 40±5% 3±15% 610±5% 350±5%
CALCE MFG Chamber Capability
Table 6 lists the capability of the MFG chamber located in CALCE rearch center at the University of Maryland. It is capable of 3 or 4 corrosive-gas-testing. The CALCE center provides quality rvices to electronic applications that require qualification test by MFG chamber. Figure 1 shows the photo of this Mixed Flowing Gas testing system.
Figure 1: MFG Chamber Located in CALCE Center at the University of Maryland
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Table 6: CALCE MFG Chamber Capability
Corrosive Gas Concentrations (ppb) Temp. Range (ºC) RH (%) NO x
张莹莹
SO 2 H 2S Cl 2 Interior Dimensions (inches) 25~50 20~95 10~1000
10~1000
10~1000
10~1000
29X30X38
References:
羊水指数正常范围
[1] American Society for Testing and Material, ASTM Designation B845-97: Standard Guide for
Mixed Flowing Gas (MFG) Tests for Electrical Contacts, 1997.
[2] Abbott, W.H., “The development and performance characteristics of flowing mixed gas test
environments,” IEEE Transactions on Components, Hybrids, and Manufacturing Technology, vol.1l, no.1, pp.22-35, Mar 1988.
[3] International Electro-technical Commission, IEC Standard 68-2-60 (cond edition)
Environmental Testing-Part 2: Tests-Flowing mixed gas corrosion test, 1995.
[4] Electronic Industries Association, EIA Standard TP-65A: Mixed Flowing Gas, Jan. 1998. [5] Telcordia GR-63-CORE Issue 2, Section 5.5, “Airborne Contaminants Test Methods”, Nov. 2000. [6] www.astm [7] www.eia [8]
www.iec.ch
[9] Gore, R.R., Witska, R., Kirby, J.R., and Chao, J.L., “Corrosive Gas Environmental Testing for
Electrical Contacts”, IEEE Transactions on Components, Packaging, and Manufacturing Technology, vol.13, Issue 1, pp.27-32, March 1990.
[10] Williams, D.W.; "The Effect of Test Environment on the Creep of Ba Metal Surface Films over
Precious Metal Inlays"; IEEE Transactions on Components, Hybrids and Manufacturing Technology; vol.11, no.1, pp.36-42, Mar. 1988.
[11] Chao, J.G., Gore, R.R., “Evaluation of a mixed flowing gas test,” 1991 Proceedings of the Thirty
Seventh IEEE Holm Conference on Electrical Contacts, pp.216-228, Piscataway, NJ: IEEE, 1991.
