ASTM B878-97(2003)
(Test Method)Standard Test Method for Nanosecond Event Detection for Electrical Contacts and Connectors
Standard Test Method for Nanosecond Event Detection for Electrical Contacts and Connectors
SIGNIFICANCE AND USE
The tests in this test method are designed to assess the resistance stability of electrical contacts or connections.
The described procedures are for the detection of events that result from short duration, high-resistance fluctuations, or of voltage variations that may result in improper triggering of high speed digital circuits.
In those procedures, the test currents are 100 mA (±20 mA) when the test sample has a resistance between 0 and 10 Ω. Since the minimum resistance change required to produce an event (defined in 3.2.1) is specified as 10 Ω (see 1.3), the voltage increase required to produce this event must be at least 1.0 V.
The detection of nanosecond-duration events is considered necessary when an application is susceptible to noise. However, these procedures are not capable of determining the actual duration of the event detected.
The integrity of nanosecond-duration signals can only be maintained with transmission lines; therefore, contacts in series are connected to a detector channel through coaxial cable. The detector will indicate when the resistance monitored exceeds the minimum event resistance for more than the specified duration.
The test condition designation corresponding to a specific minimum event duration of 1, 10, or 50 ns is listed in Table 1. These shall be specified in the referencing document.
TABLE 1 Test Condition Designations for Specific Minimum Event Durations Test ConditionEvent Duration, min A 1 nanosecond B10 nanoseconds C50 nanoseconds
SCOPE
1.1 This test method describes equipment and techniques for detecting contact resistance transients yielding resistances greater than a specified value and lasting for at least a specified minimum duration.
1.2 The minimum durations specified in this standard are 1, 10, and 50 nanoseconds (ns).
1.3 The minimum sample resistance required for an event detection in this standard is 10 Ω.
1.4 An ASTM guide for measuring electrical contact transients of various durations is available as Guide B 854.
1.5 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.
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Designation: B 878 – 97 (Reapproved 2003)
Standard Test Method for
Nanosecond Event Detection for Electrical Contacts and
Connectors
This standard is issued under the fixed designation B 878; 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 4. Significance and Use
1.1 This test method describes equipment and techniques 4.1 The tests in this test method are designed to assess the
for detecting contact resistance transients yielding resistances resistance stability of electrical contacts or connections.
greater than a specified value and lasting for at least a specified 4.2 The described procedures are for the detection of events
minimum duration. that result from short duration, high-resistance fluctuations, or
1.2 The minimum durations specified in this standard are 1, of voltage variations that may result in improper triggering of
10, and 50 nanoseconds (ns). high speed digital circuits.
1.3 The minimum sample resistance required for an event 4.3 In those procedures, the test currents are 100 mA (620
detection in this standard is 10 V. mA)whenthetestsamplehasaresistancebetween0and10 V.
1.4 An ASTM guide for measuring electrical contact tran- Since the minimum resistance change required to produce an
sients of various durations is available as Guide B 854. event (defined in 3.2.1) is specified as 10 V (see 1.3), the
1.5 This standard does not purport to address all of the voltage increase required to produce this event must be at least
safety concerns, if any, associated with its use. It is the 1.0 V.
responsibility of the user of this standard to establish appro- 4.4 The detection of nanosecond-duration events is consid-
priate safety and health practices and determine the applica- ered necessary when an application is susceptible to noise.
bility of regulatory limitations prior to use. However, these procedures are not capable of determining the
actual duration of the event detected.
2. Referenced Documents
4.5 The integrity of nanosecond-duration signals can only
2.1 ASTM Standards:
be maintained with transmission lines; therefore, contacts in
B 542 Terminology Relating to Electrical Contacts and
series are connected to a detector channel through coaxial
Their Use cable.The detector will indicate when the resistance monitored
B 854 Guide for Measuring Electrical Contact Intermit-
exceeds the minimum event resistance for more than the
tences specified duration.
2.2 Other Standards:
4.6 The test condition designation corresponding to a spe-
IEC 801-2, ed 2:91 cific minimum event duration of 1, 10, or 50 ns is listed in
EN 50 082-1:94
Table 1. These shall be specified in the referencing document.
3. Terminology 5. Apparatus
3.1 Definitions: Many terms used in this standard are
5.1 Detector—The detector used shall be an AnaTech 64
defined in Terminology B 542. EHD, 32 EHD, or equivalent. The detector shall meet the
3.2 Definitions of Terms Specific to This Standard:
following requirements:
3.2.1 event—a condition in which the sample resistance 5.1.1 Electromagnetic Interference (EMI)—The detector
increases by more than 10 V for more than a specified time
shall pass the European Community (EC) electrostatic dis-
duration. charge (ESD) requirement for computers (EN50 082-1:94
based on IEC 801-2, ed. 2:91). The performance criteria is “1)
normal performance within the specification limits;” that is, no
This test method is under the jurisdiction of ASTM Committee B02 on
channel is allowed to trip.Air discharge voltages shall include
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
2, 4, 8, and 15 kV. Contact discharge voltages shall include 2,
B02.11 on Electrical Contact Test Methods.
Current edition approved June 10, 2003. Published July 2003. Originally
4, 6, and 8 kV. Detector inputs shall be protected with coaxial
approved in 1997. Last previous edition approved in 1997 as B 878 - 97.
shorts.
Annual Book of ASTM Standards, Vol 02.04.
Available from American National Standards Institute, 11 W. 42nd St., 13th
Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B 878 – 97 (2003)
TABLE 1 Test Condition Designations for Specific Minimum
Event Durations
Test Condition Event Duration, min
A 1 nanosecond
B 10 nanoseconds
C 50 nanoseconds
5.1.2 dc Current—Each channel shall supply 100 6 20 mA
whenthesamplebeingtestedhasaresistancebetween0and10
V.
5.1.3 Input Impedance:
5.1.3.1 Direct Current (dc)—The detector source resistance
(impedance) shall be 50 V when the sample resistance is
between 0 and 10 V.
5.1.3.2 RF Input Impedance—ATime Domain Reflectome-
ter (TDR) or Network Analyzer Time Domain Reflectometer
(NATDR) shall be used to measure the reflection in percent of
a (simulated) 0.5 ns risetime step when the sample direct
current resistance is 10 V and the detector current is 100 mA.
(The 10 V sample resistance is put on the bias port for
NOTE 1—
NATDR.) An acceptable detector shall reflect less than 30 %
A One square meter EMI loop monitored at top center (see 6.1).
amplitude.
B Connection to series wired sample circuit with the greatest capacitance
5.1.4 Amplitude Sensitivity—Amplitude required to trip the
detector with a 1 nanosecond duration pulse shall be no more
shell or other metal fixturing (see 6.1).
than 120 % of the direct current trip amplitude. One nanosec-
C Miniature coaxial cable (50 V) (see 5.3.1.1).
ond pulse duration shall be measured at 90 % of the pulse
D Patch panel, coaxial through-bulkhead RF connectors in metal panel.
amplitude, and the rise and fall times shall be less than 0.5 ns.
E Short flexible ground strap, 70 mm long and >25 mm wide (see 7.3).
F Strain relief coaxial cable at these locations.
Pulse low level shall be 0 V. These shall be measured with a 1
G Physical support for patch panel.
GHzbandwidthoscilloscopeandapulsegenerator(seeFig.1).
H RG-223 double braid coaxial cable.
5.1.4.1 The same requirements shall be met for the 10 and
FIG. 2 Ten and Fifty Nanosecond Fixturing
50nsdetectorsettings,butthepulseriseandfalltimescannow
be less than 2 ns.
5.3.1.1 A contact or series-wired contacts (see Fig. 3, Note
5.1.5 Accuracy—Itshallbepossibletoadjustthedetectorto
A) shall be wired from the center conductor to the braid of
trip at 10 6 1 V for all channels in use.
miniature 50-V coaxial cable (see Fig. 2, Note C).
5.2 Test Setup—Recommended equipment is as shown in
5.3.1.2 The sample, as wired to the miniature coaxial cable
Fig. 2. A short flexible ground strap directs ground loop
for testing, shall be capable of passing short duration pulses.A
currents away from the sample (see Fig. 2, Note E). The
time domain reflectometer (TDR) shall be used to measure the
RG-223 coaxial cable is well shielded whereas the short 50 V
transition time of a fast risetime step (<60 ps) reflected from
miniaturecoaxialcableisflexible.EachEMIloopisconnected
the sample under test. On the waveform, find the point
to a detector channel and is used as a control.
representing the far end of the miniature 50-V coaxial cable
5.3 Sample and EMI Loop Preparation—Thesamplecircuit
(see Fig. 4, Point 1). Also find the last point on the waveform
shall have a resistance of less than 4 V.
where the voltage amplitude is 20 % of Point 1 (see Fig. 4,
5.3.1 Sample Wiring:
Point 2). The time between these points shall be less than the
minimum duration of the event identified in Table 1. Each
series-wired sample circuit shall be measured.
5.3.2 Electromagnetic Interference (EMI) Concerns of
Sample Wiring—At least three major paths for EMI can be
identified in the sample fixturing.
5.3.2.1 EMI couples to the sample through the parasitic
capacitance between the sample and any metal fixturing. To
greatly reduce this coupling, the miniature coaxial cable shield
shall be connected to the metal fixturing as close to the
connector-under-test as possible. This connection shall be as
short as possible and p
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