1、Designation: B 878 97 (Reapproved 2003)Standard Test Method forNanosecond Event Detection for Electrical Contacts andConnectors1This standard is issued under the fixed designation B 878; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes equipment and techniquesfor detecting contact resistance transients yieldi
3、ng resistancesgreater than a specified value and lasting for at least a specifiedminimum 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 eventdetection in this standard is 10 V.1.4 An ASTM guide for mea
4、suring electrical contact tran-sients of various durations is available as Guide B 854.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices
5、and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:B 542 Terminology Relating to Electrical Contacts andTheir Use2B 854 Guide for Measuring Electrical Contact Intermit-tences22.2 Other Standards:IEC 801-2, ed 2:913EN 50 082-1:9433. Termi
6、nology3.1 Definitions: Many terms used in this standard aredefined in Terminology B 542.3.2 Definitions of Terms Specific to This Standard:3.2.1 eventa condition in which the sample resistanceincreases by more than 10 V for more than a specified timeduration.4. Significance and Use4.1 The tests in t
7、his test method are designed to assess theresistance stability of electrical contacts or connections.4.2 The described procedures are for the detection of eventsthat result from short duration, high-resistance fluctuations, orof voltage variations that may result in improper triggering ofhigh speed
8、digital circuits.4.3 In those procedures, the test currents are 100 mA (620mA) when the test sample has a resistance between 0 and 10 V.Since the minimum resistance change required to produce anevent (defined in 3.2.1) is specified as 10 V (see 1.3), thevoltage increase required to produce this even
9、t must be at least1.0 V.4.4 The detection of nanosecond-duration events is consid-ered necessary when an application is susceptible to noise.However, these procedures are not capable of determining theactual duration of the event detected.4.5 The integrity of nanosecond-duration signals can onlybe m
10、aintained with transmission lines; therefore, contacts inseries are connected to a detector channel through coaxialcable. The detector will indicate when the resistance monitoredexceeds the minimum event resistance for more than thespecified duration.4.6 The test condition designation corresponding
11、to a spe-cific minimum event duration of 1, 10, or 50 ns is listed inTable 1. These shall be specified in the referencing document.5. Apparatus5.1 DetectorThe detector used shall be an AnaTech 64EHD, 32 EHD, or equivalent. The detector shall meet thefollowing requirements:5.1.1 Electromagnetic Inter
12、ference (EMI)The detectorshall pass the European Community (EC) electrostatic dis-charge (ESD) requirement for computers (EN50 082-1:94based on IEC 801-2, ed. 2:91). The performance criteria is “1)normal performance within the specification limits;” that is, nochannel is allowed to trip. Air dischar
13、ge voltages shall include2, 4, 8, and 15 kV. Contact discharge voltages shall include 2,4, 6, and 8 kV. Detector inputs shall be protected with coaxialshorts.1This test method is under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and is the direct responsibility of Subcommit
14、teeB02.11 on Electrical Contact Test Methods.Current edition approved June 10, 2003. Published July 2003. Originallyapproved in 1997. Last previous edition approved in 1997 as B 878 - 97.2Annual Book of ASTM Standards, Vol 02.04.3Available from American National Standards Institute, 11 W. 42nd St.,
15、13thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.1.2 dc CurrentEach channel shall supply 100 6 20 mAwhen the sample being tested has a resistance between 0 and 10V.5.1.3 Input Impedance:5.1.3.1 Direct C
16、urrent (dc)The detector source resistance(impedance) shall be 50 V when the sample resistance isbetween 0 and 10 V.5.1.3.2 RF Input ImpedanceA Time Domain Reflectome-ter (TDR) or Network Analyzer Time Domain Reflectometer(NATDR) shall be used to measure the reflection in percent ofa (simulated) 0.5
17、ns risetime step when the sample directcurrent resistance is 10 V and the detector current is 100 mA.(The 10 V sample resistance is put on the bias port forNATDR.) An acceptable detector shall reflect less than 30 %amplitude.5.1.4 Amplitude SensitivityAmplitude required to trip thedetector with a 1
18、nanosecond duration pulse shall be no morethan 120 % of the direct current trip amplitude. One nanosec-ond pulse duration shall be measured at 90 % of the pulseamplitude, and the rise and fall times shall be less than 0.5 ns.Pulse low level shall be 0 V. These shall be measured with a 1GHz bandwidth
19、 oscilloscope and a pulse generator (see Fig. 1).5.1.4.1 The same requirements shall be met for the 10 and50 ns detector settings, but the pulse rise and fall times can nowbe less than 2 ns.5.1.5 AccuracyIt shall be possible to adjust the detector totrip at 10 6 1 V for all channels in use.5.2 Test
20、SetupRecommended equipment is as shown inFig. 2. A short flexible ground strap directs ground loopcurrents away from the sample (see Fig. 2, Note E). TheRG-223 coaxial cable is well shielded whereas the short 50 Vminiature coaxial cable is flexible. Each EMI loop is connectedto a detector channel an
21、d is used as a control.5.3 Sample and EMI Loop PreparationThe sample circuitshall have a resistance of less than 4 V.5.3.1 Sample Wiring:5.3.1.1 A contact or series-wired contacts (see Fig. 3, NoteA) shall be wired from the center conductor to the braid ofminiature 50-V coaxial cable (see Fig. 2, No
22、te C).5.3.1.2 The sample, as wired to the miniature coaxial cablefor testing, shall be capable of passing short duration pulses. Atime domain reflectometer (TDR) shall be used to measure thetransition time of a fast risetime step (25 mm wide (see 7.3).F Strain relief coaxial cable at these locations
23、.G Physical support for patch panel.H RG-223 double braid coaxial cable.FIG. 2 Ten and Fifty Nanosecond FixturingB 878 97 (2003)2all connections to metal fixturing in this standard may be ignored.5.3.2.2 Large EMI currents in adjacent contacts can couplethrough crosstalk or capacitance to monitored
24、channels. Toreduce this, no conductor of any type may be connected tocontacts not being monitored for the event. It is recommendedthat monitored contacts be evenly distributed around theconnector to minimize crosstalk with other monitored channels(see Fig. 3, Note B).5.3.2.3 The loop area of the sam
25、ple circuits shall be mini-mized to reduce magnetic field coupling.5.3.3 Control Channel(s)Anytime a failure is indicated, itis possible that the real cause was actually electromagneticinterference (EMI), and not the connector-under-test. The goalof the control channel(s) is to detect EMI at levels
26、much lowerthan required to trigger an event on a sample channel. Duringtesting, the control channels shall be monitored with the samedetector values as used on the sample circuits. An eventobserved on a control channel invalidates any other eventsdetected during the polling period. See 7.6 to define
27、 pollingperiod.6. Preliminary Procedures6.1 For Test Conditions B and C (Ten and Fifty nanosec-onds, respectively):6.1.1 A control channel shall consist of a separate loop ofwire with an area of one square meter suspended above thesample(s) and monitored through a miniature coaxial cableattached at
28、the top center of the loop (see Fig. 2, Notes A andB).6.1.2 Find the series wired circuit with the greatest capaci-tance to the fixturing metal, measured without any coaxialcable attached. Instead of connecting this to a miniature coaxialcable, connect it to the center of the control channel loop,op
29、posite the coaxial cable connection (see Fig. 2, Note B). Aseparate sample may be required if the sample has only onecontact.6.2 For Test Condition A (One nanosecond):6.2.1 Three control channels shall be provided, consisting of3 nested, mutually perpendicular loops (see Fig. 5). Each loopshall have
30、 a nominal area of 36 square cm (for example,6 3 66 0.5 cm). These loops shall be suspended over thesample(s).6.2.2 Find the series-wired circuit with the greatest capaci-tance to the fixturing metal, measured without any coaxialcable attached. Instead of connecting this to a miniature coaxialcable,
31、 connect it to the center of one of the control channelloops, opposite the coaxial cable connection. A separate samplemay be required if the sample has only one contact.NOTE 1A Series-wired contacts (see 5.3.1).B Contacts skipped to reduce crosstalk (see 5.3.2.2).C The circuit with maximum capacitan
32、ce to fixture (see 6.1.1).D The very short miniature coaxial cable ground (see 5.3.2.1).FIG. 3 Example of Series-Wired SampleNOTE 1Requirement is that Point 2Point 1 minimum event dura-tion from Fig. 1.FIG. 4 TDR Measurement Trace of Sample CircuitFIG. 5 One Nanosecond Fixturing with Nested 6 3 6cmE
33、MILoops (see 6.2.1)B 878 97 (2003)37. Procedure7.1 Prepare samples and measure the fall time per 5.3.1.2,using TDR. If this requirement cannot be met, fewer contactsin series or better fixture wiring may be required.7.2 Place the EMI loop(s) of 5.3.3 over the sample andconnect to the sample circuit
34、with the greatest capacitance.7.3 Assemble the equipment as indicated in Fig. 2 (or Fig. 5for one nanosecond). The 50 V miniature coaxial cable andespecially the ground strap shall be kept as short as practical(see Fig. 2, Note E). Additionally, the miniature coaxial cableground connection to connec
35、tor shell or metal fixturing, orboth, shall be as short as possible and perpendicular to nearbysample conductors (see 5.3.2.1 and Fig. 3).7.4 Turn on the equipment. Set the equipment to deliver 1006 20 mA. Also set the detector to trip at 10 V above the initialresistance. Reset all channels. If the
36、Detail Specificationspecifies using a current less than 80 mA or a thresholdresistance less than 10 V, it may be necessary to add additionalshielding, or to locate the test equipment in a shielded room orbox.7.5 Disconnect each sample from the detector by unmatingthe coaxial connectors. Confirm that
37、 the indicator trips whendisconnected, as a functional check.7.6 Apply the desired environmental stress to the connector-under-test. The test should be broken up into equal-length timeperiods. At the end of each, the status of each channel shouldbe polled. Any events detected during a polling period
38、 whichalso registers an event on a control channel shall be consideredEMI induced (not a connector failure).7.7 At the end of testing, the failure indications at differentpolling times should be analyzed for patterns suggesting EMI,such as simultaneous events in different channels.8. Report8.1 In re
39、porting the results of the test, the following infor-mation shall be given:8.1.1 Contact positions tested on each channel.8.1.2 Connectors tested.8.1.3 Sample lead dress description (for example, how is theconnection made between the coaxial cable and the sampleconductors, or how is the wiring accom
40、plished between sampleconductors in series, etc.) or diagram.8.1.4 EMI event history, detected on the EMI loop.8.1.5 Environmental stresses applied.8.1.6 Detected event history for each channel.8.1.7 TDR results on sample setup verification.8.1.8 Name of operator and date of test.NOTE 2The following
41、 details shall be specified in the referencingdocument:(a) Samples and contacts to be tested.(b) 1, 10, or 50 ns minimum duration.(c) Resistance increase, if other than 10 V.(d) Current, if other than 100 mA.9. Precision and Bias9.1 PrecisionTest precision is determined by detectorperformance. One u
42、nit was evaluated which consisted of 64detectors. In the 50 ns position, the duration sensitivity rangedbetween 45.4 and 51.0 ns (pulse amplitude twice the dc tripvalue). In the 10 ns position, it ranged between 8.5 and 9.7 ns.In the 1 ns position,a1nspulse tripped two detectors whenthey had a peak
43、amplitude equal to the dc trip voltage (otherchannels not tested). Thus, voltage amplitude sensitivity didnot change between dc and the shortest duration of this teststandard. All 64 channels were checked for the same using a1.9 ns duration (90 % amplitude) pulse. The total variation was63%.9.2 Bias
44、This standard requires the detector to have asample current tolerance and a given minimum (voltage)amplitude sensitivity to each event duration (see 5.1). The mostsignificant possible errors will be EMI-produced false failureindications. Since each test location will have a different EMIenvironment,
45、 such errors will be impossible to predict pre-cisely.10. Keywords10.1 event detection; nanosecond events; nanosecondintermittencesASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard
46、are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif no
47、t revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which
48、you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).B 878 97 (2003)4
