1、Designation: B878 97 (Reapproved 2014)Standard Test Method forNanosecond Event Detection for Electrical Contacts andConnectors1This standard is issued under the fixed designation B878; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes equipment and techniquesfor detecting contact resistance transients yielding
3、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 .1.4 An ASTM guide for measuri
4、ng electrical contact tran-sients of various durations is available as Guide B854.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated wi
5、th its use. It is theresponsibility of the user of this standard to become familiarwith all hazards including those identified in the appropriateMaterial Safety Data Sheet (MSDS) for this product/materialas provided by the manufacturer, to establish appropriatesafety and health practices, and determ
6、ine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B542 Terminology Relating to Electrical Contacts and TheirUseB854 Guide for Measuring Electrical Contact Intermittences2.2 Other Standards:IEC 801-2 ed 2:913EN 50 082-1:9433. Terminology3.1 Definit
7、ionsMany terms used in this standard are de-fined in Terminology B542.3.2 Definitions of Terms Specific to This Standard:3.2.1 event, na condition in which the sample resistanceincreases by more than 10 for more than a specified timeduration.4. Significance and Use4.1 The tests in this test method a
8、re 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 digital circuits.
9、4.3 In those procedures, the test currents are 100 mA (620mA) when the test sample has a resistance between 0 and 10.Since the minimum resistance change required to produce anevent (defined in 3.2.1) is specified as 10 (see 1.3), thevoltage increase required to produce this event must be at least1.0
10、 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 maintained with transm
11、ission 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 to a spe-cific minimu
12、m event duration of 1, 10, or 50 ns is listed inTable 1. These shall be specified in the referencing document.1This test method is under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and is the direct responsibility of SubcommitteeB02.11 on Electrical Contact Test Methods.Cur
13、rent edition approved Oct. 1, 2014. Published October 2014. Originallyapproved in 1997. Last previous edition approved in 2009 as B878 97 (2009).DOI: 10.1520/B0878-97R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annu
14、al Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700
15、, West Conshohocken, PA 19428-2959. United States15. Apparatus5.1 DetectorThe detector used shall be an AnaTech 64EHD, 32 EHD, or equivalent. The detector shall meet thefollowing requirements:5.1.1 Electromagnetic Interference (EMI)The detectorshall pass the European Community (EC) electrostatic dis
16、-charge (ESD) requirement for computers (EN 50 082-1:94based 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 discharge voltages shall include2, 4, 8, and 15 kV. Contact discharge voltages shall in
17、clude 2,4, 6, and 8 kV. Detector inputs shall be protected with coaxialshorts.5.1.2 dc CurrentEach channel shall supply 100 6 20 mAwhen the sample being tested has a resistance between 0 and 10.5.1.3 Input Impedance:5.1.3.1 Direct Current (dc)The detector source resistance(impedance) shall be 50 whe
18、n the sample resistance isbetween 0 and 10 .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 ns risetime step when the sample directcurrent resistance is 10 and the
19、 detector current is 100 mA.(The 10 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 nanosecond duration pulse shall be no morethan 120 % of the direct current
20、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 oscilloscope and a pulse generator (see Fig. 1).5.1.4.1 The same requireme
21、nts 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 for all channels in use.5.2 Test SetupRecommended equipment is as shown inFig. 2. A short flexible ground stra
22、p directs ground loopcurrents away from the sample (see Fig. 2, Note E). TheRG-223 coaxial cable is well shielded whereas the short 50 miniature coaxial cable is flexible. Each EMI loop is connectedto a detector channel and is used as a control.5.3 Sample and EMI Loop PreparationThe sample circuitsh
23、all have a resistance of less than 4 .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- coaxial cable (see Fig. 2, Note C).5.3.1.2 The sample, as wired to the miniature coaxial cablefor testing, sh
24、all 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.G Physical support for patch panel.H RG-223 double braid coaxial cable.FIG. 2 T
25、en and Fifty Nanosecond FixturingB878 97 (2014)2minimum duration of the event identified in Table 1. Eachseries-wired sample circuit shall be measured.5.3.2 Electromagnetic Interference (EMI) Concerns ofSample WiringAt least three major paths for EMI can beidentified in the sample fixturing.5.3.2.1
26、EMI couples to the sample through the parasiticcapacitance between the sample and any metal fixturing. Togreatly reduce this coupling, the miniature coaxial cable shieldshall be connected to the metal fixturing as close to theconnector-under-test as possible. This connection shall be asshort as poss
27、ible and perpendicular to nearby sample conduc-tors (see Fig. 3, Note D). This is done for the sample channelsonly, not the control channels.NOTE 1If there is no metal fixturing within 5 cm of the sample circuit,all connections to metal fixturing in this standard may be ignored.5.3.2.2 Large EMI cur
28、rents in adjacent contacts can couplethrough crosstalk or capacitance to monitored 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
29、 with other monitored channels(see Fig. 3, Note B).5.3.2.3 The loop area of the sample 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
30、connector-under-test. The goalof the control channel(s) is to detect EMI at levels 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 channe
31、l invalidates any other eventsdetected during the polling period. See 7.6 to define pollingperiod.6. Preliminary Procedures6.1 For Test Conditions B and C (Ten and Fiftynanoseconds, respectively):6.1.1 A control channel shall consist of a separate loop ofwire with an area of one square meter suspend
32、ed above thesample(s) and monitored through a miniature coaxial cableattached at 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
33、a miniature coaxialcable, connect it to the center of the control channel loop,opposite 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, cons
34、isting of3 nested, mutually perpendicular loops (see Fig. 5). Each loopshall have a nominal area of 36 square cm (for example, 6 66 0.5 cm). These loops shall be suspended over the sample(s).6.2.2 Find the series-wired circuit with the greatest capaci-tance to the fixturing metal, measured without a
35、ny coaxialcable attached. Instead of connecting this to a miniature coaxialcable, connect it to the center of one of the control channelloops, opposite the coaxial cable connection.Aseparate samplemay be required if the sample has only one contact.7. Procedure7.1 Prepare samples and measure the fall
36、 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 with the greatest capacitance.7.3 Assemble the equipment as indicated in Fig. 2 (or Fig
37、. 5for one nanosecond). The 50 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 connector shell or metal fixturing, orNOTE 1A Series-wired contacts (see 5.3.1).B Contacts skip
38、ped to reduce crosstalk (see 5.3.2.2).C The circuit with maximum capacitance 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 durationfrom Fig. 1.FIG. 4 TDR Measurement Tra
39、ce of Sample CircuitB878 97 (2014)3both, 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 above the initialresistance. Reset all channels. If the
40、Detail Specificationspecifies using a current less than 80 mA or a thresholdresistance less than 10, 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 t
41、he 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 w
42、hichalso 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 repo
43、rting 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 accompl
44、ished 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 d
45、etails 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 .(d) Current, if other than 100 mA.9. Precision and Bias9.1 PrecisionTest precision is determined by detectorperformance. One unit
46、 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 amp
47、litude 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 BiasThi
48、s 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, su
49、ch errors will be impossible to predict pre-cisely.10. Keywords10.1 event detection; nanosecond events; nanosecond inter-mittencesASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard 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 techni
