ASTM B878-97

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.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 878 – 97
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) when the test sample has a resistance between 0 and 10 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
tence 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
1 channel is allowed to trip. Air discharge voltages shall include
This test method is under the jurisdiction of ASTM Committee B-2 on
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.
4, 6, and 8 kV. Detector inputs shall be protected with coaxial
Current edition approved Jan. 10, 1997. Published March 1997.
shorts.
Annual Book of ASTM Standards, Vol 02.04.
5.1.2 dc Current—Each channel shall supply 100 6 20 mA
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.
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 878
TABLE 1 Test Condition Designations for Specific Minimum
Event Durations
Test Condition Event Duration, min
A 1 nanosecond
B 10 nanoseconds
C 50 nanoseconds
when the sample being tested has a resistance between 0 and 10
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—A Time 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
NATDR.) An acceptable detector shall reflect less than 30 %
amplitude.
5.1.4 Amplitude Sensitivity—Amplitude required to trip the NOTE 1—
A One square meter EMI loop monitored at top center (see 6.1).
detector with a 1 nanosecond duration pulse shall be no more
B Connection to series wired sample circuit with the greatest capacitance
than 120 % of the direct current trip amplitude. One nanosec-
ond pulse duration shall be measured at 90 % of the pulse
shell or other metal fixturing (see 6.1).
amplitude, and the rise and fall times shall be less than 0.5 ns.
C Miniature coaxial cable (50 V) (see 5.3.1.1).
Pulse low level shall be 0 V. These shall be measured with a 1
D Patch panel, coaxial through-bulkhead RF connectors in metal panel.
GHz bandwidth oscilloscope and a pulse generator (see Fig. 1).
E Short flexible ground strap, 70 mm long and >25 mm wide (see 7.3).
F Strain relief coaxial cable at these locations.
5.1.4.1 The same requirements shall be met for the 10 and
G Physical support for patch panel.
50 ns detector settings, but the pulse rise and fall times can now
H RG-223 double braid coaxial cable.
be less than 2 ns.
FIG. 2 Ten and Fifty Nanosecond Fixturing
5.1.5 Accuracy—It shall be possible to adjust the detector to
trip at 10 6 1 V for all channels in use.
5.3.1.2 The sample, as wired to the miniature coaxial cable
5.2 Test Setup—Recommended equipment is as shown in
for testing, shall be capable of passing short duration pulses. A
Fig. 2. A short flexible ground strap directs ground loop
time domain reflectometer (TDR) shall be used to measure the
currents away from the sample (see Fig. 2, Note E). The
transition time of a fast risetime step (<60 ps) reflected from
RG-223 coaxial cable is well shielded whereas the short 50 V
the sample under test. On the waveform, find the point
miniature coaxial cable is flexible. Each EMI loop is connected
representing the far end of the miniature 50-V coaxial cable
to a detector channel and is used as a control.
(see Fig. 4, Point 1). Also find the last point on the waveform
5.3 Sample and EMI Loop Preparation—The sample circuit
where the voltage amplitude is 20 % of Point 1 (see Fig. 4,
shall have a resistance of less than 4 V.
Point 2). The time between these points shall be less than the
5.3.1 Sample Wiring:
minimum duration of the event identified in Table 1. Each
5.3.1.1 A contact or series-wired contacts (see Fig. 3, Note
series-wired sample circuit shall be measured.
A) shall be wired from the center conductor to the braid of
5.3.2 Electromagnetic Interference (EMI) Concerns of
miniature 50-V coaxial cable (see Fig. 2, Note C).
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 perpendicular to nearby sample conduc-
tors (see Fig. 3, Note D). This is done for the sample channels
only, not the control channels.
NOTE 1—If ther
...