1、Designation: B 794 97 (Reapproved 2003)Standard Test Method forDurability Wear Testing of Separable Electrical ConnectorSystems Using Electrical Resistance Measurements1This standard is issued under the fixed designation B 794; the number immediately following the designation indicates the year ofor
2、iginal adoption or, in the case of revision, 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 covers the effects of repeated insertionand
3、 withdrawal of separable electrical connectors which areharmful to the electrical performance of the connector.1.2 This test method is limited to electrical connectorsdesigned for use in applications where the current through anyone connection in the connector does not exceed 5 A, andwhere the conne
4、ctor may be separated a number of timesduring the life of the connector.1.3 This test method is limited to electrical connectorsintended for use in air ambients where the operating tempera-ture is less than 65C.1.4 This standard does not purport to address all of thesafety concerns, if any, associat
5、ed with 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 for this product/material as pro-vided by the manufacturer, to establish appropriate safety andhealth practices, and determ
6、ine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:B 539 Test Methods for Measuring Resistance of ElectricalConnections (Static Contacts)22.2 Military Standard:3MIL-STD-1344A Test Methods for Electrical Connectors3. Summary of Test Method3.1 Sample
7、connectors are wired for precision resistancemeasurements of each test contact. The samples are dividedinto two groups; then resistance measurements are made ofeach test contact. The connectors in one group undergo anumber of insertion/withdrawal cycles appropriate for theparticular connector under
8、test, and the resistances of theseconnectors are measured again. The connectors in the othergroup are not disturbed. All samples are subjected to anaccelerated aging test; then the resistances are measured again.All samples are separated (withdrawn), exposed to an acceler-ated aging test in the unin
9、serted condition, removed from thetest, reinserted, and resistances measured again. The variousresistance measurements are compared to detect effects of thewear and aging on electrical performance.4. Significance and Use4.1 Materials for electrical connector contacts must satisfy anumber of requirem
10、ents in the areas of electrical, mechanical,and economic characteristics. The stability of electrical prop-erties is one of the most important of these characteristics.Wear of contact surfaces may adversely affect these electricalproperties, especially in designs where the contact surfaces arerelati
11、vely thin coatings. This test method provides a means tocompare various material systems on a basis relevant to theirapplication in electrical connector contacts.4.2 Repeated insertion and withdrawal of a connector maycause wear or other mechanical damage to the electricalcontact surfaces, rendering
12、 those surfaces more susceptible toenvironmental degradation. This test method is intended todetect degradation of the electrical properties of the connectorby such processes.4.3 This test method describes procedures for conductingwear and durability testing of electrical connectors; the proce-dures
13、 produce quantitative results. These results may be usedto compare the performance of different connector designs sothat meaningful design choices can be made. Such results mayalso be used to compare the performance of a connector to apreviously established standard to evaluate the quality of thesam
14、ples under test.4.4 The test results obtained from this test method arelimited in their applicability to connector combinations that areequivalent in design and manufacture to those actually tested.4.5 The user is cautioned that the conditions in this testshould be compared to the conditions that th
15、e connector willexperience in the intended application in order to determine therelevance of this test method to the particular needs of the user.For example, the environmental stress in this test method is1This test method is under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Allo
16、ys and is the direct responsibility of SubcommitteeB02.11 on Electrical Contact Test Methods.Current edition approved June 10, 2003. Published July 2003. Originallyapproved in 1988. Last previous edition approved in 1997 as B 794 97.2Annual Book of ASTM Standards, Vol 03.04.3Available from Standardi
17、zation Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.less severe than certain industrial and marine environments andtherefore test r
18、esults are not directly applicable to predict theperformance of product intended for use in such areas.4.6 It is recommended that this test method be used in oneof two ways. First, it may be used to evaluate and report theperformance of a particular connector system. In such a case,it is appropriate
19、 to report the results in a table in the formatshown in Fig. 1 and to state “The results shown in the tablewere obtained for (insert connector designation or description)when tested in accordance with ASTM Standard B 794,Method _ , Procedure _ .” Second, it may be used to imposerequirements for acce
20、ptance of product. In this case, limits forthe values shown in Fig. 1 must be established prior to productacceptance testing. Such limits may be established by variousmethods such as by evaluation of product which is known to beacceptable or by application of appropriate experience. Theselimits must
21、 be documented in a manner that the entityperforming the product test can refer to the limits to determineif the test product conforms to such limits. A purchaser maywish to supply a table of limits and include on the purchaseorder a statement similar to: “The product, when tested inaccordance with
22、ASTM Standard B 794, Method _ , Proce-dure _ , shall meet the limits in the supplied table.” This tablesupplied by the purchaser may set limits on all of the values inFig. 1, or only on a subset of those values that the purchaserdeems adequate to ensure the performance of the product.5. Apparatus5.1
23、 Environmental Test Chamber, capable of controlling thetest ambient in accordance with the sequence shown in Table 1.The test chamber shall be sufficiently large that each testsample shall be positioned with at least 100 mm separating itfrom the nearest wall of the test chamber. The test chamberdesi
24、gn and operation procedure shall conform to the require-ments contained in MIL-STD-1344A, Method 1002.2.5.2 An instrument is required for measuring resistance bythe four-wire method. This instrument shall operate within thelimits on current and open-circuit voltage set forth in TestMethods B 539, Te
25、st Method C. The instrument shall becapable of measuring a resistance less than 0.100 V with aresolution of 0.0001 V. For a resistance 0.100 V or larger, theinstrument shall be capable of measuring it with a resolution of0.1 % of the resistance value.6. Sampling and Test Specimens6.1 Selection of Sa
26、mple ConnectorsObtain sufficientsample connectors so that the electrical resistance of at least200 contacts contained in at least 20 separate connectors willbe measured in the test. Obtain sample connectors that arerepresentative of those that will be used in the intendedapplication. Recognize that
27、a connector consists of two halvesand both halves must be representative of the product to beused. In some cases one half will be a conductive area or padon a printed wiring-board surface, therefore printed wiringboards must be obtained that have representative conductivepads. Specifically, the cond
28、uctive pads shall be manufacturedto the same requirements as those that will be required of partsto be used in the system application. These requirements willnormally cover the manufacturing process, thickness, compo-sition, hardness, and roughness of both the finish coating and ofany underplating o
29、r undercoating. Protective treatments, ifused, shall also be specified. For the purpose of connectortesting, such printed wiring boards are generally fabricatedwith appropriate circuitry to permit four-wire resistance mea-surements.6.2 Selection of Sample ContactsIn the case where thesamples are mul
30、ticontact connectors and electrical measure-ments are performed only on a fraction of the total number ofcontacts, the contacts measured shall be distributed throughoutthe field of contacts. Measure the corresponding contacts ineach sample connector.7. Conditioning7.1 An electrical measurement labor
31、atory is required inwhich the ambient temperature is controlled to 23 6 5C andthe relative humidity is held below 60 %. This laboratory neednot be dedicated to this test program to the exclusion of otherFIG. 1 Sample Format for Reporting ResultsTABLE 1 Environmental Test SequenceNOTE 1Tolerance on t
32、emperature control is 62.Step Elapsed Time,hTemperature,CRelative Humidity,%1 02.5 ascending, 2565 92 6 32 2.55.5 65 92 6 33 5.58 descending, 6525 87 6 84 810.5 ascending, 2565 92 6 35 10.513.5 65 92 6 36 13.516 descending, 6525 87 6 87 1624 25 92 6 3B 794 97 (2003)2uses so long as those other uses
33、do not degrade the quality ofdata obtained on the connector test samples.8. Procedure8.1 Selection of Test MethodSelect a test method from thefollowing table which is appropriate for connector design andapplication.Method Number of InsertionsA5B10C25D5E 100F 200G 400H (number selected per agreementb
34、etween producer and user)8.2 Sample Preparation:8.2.1 Assemble the connectors into mounting plates, guides,fixtures, racks, or similar apparatus if such apparatus isgenerally used in the actual application of the connector.Perform such assembly at the time in the sample wiring processthat best simul
35、ates the typical manner in which the connectorsare assembled into a system.8.2.2 Wire samples for evaluation by this test method forelectrical resistance measurements before the two connectorhalves are plugged together. The wiring and resistance mea-suring circuitry shall be of the four-wire type as
36、 described inTest Methods B 539. Do the wiring in a manner that is typicalof the way the connector would be wired in service, andespecially in a manner that does not introduce unrealisticcontaminants or mechanical stresses on the connector. Do notperform cleaning, lubrication, or other treatments of
37、 theconnector unless such treatments are specified by the connectormanufacturer or user as the required procedure for the appli-cation of the particular connector under test.8.2.3 Wire at least one reference resistor for resistancemeasurements in such a manner that its resistance may bemeasured usin
38、g the same instrumentation and procedures as areused for the test contacts. It is suggested that this referenceresistor be a length of wire or a path on a printed wiring boardwith a resistance of the same order of magnitude as that oftypical test contacts. Measure and record the resistance of thisre
39、ference resistor each time that the test contacts are measured.Expose this reference resistor to the same test environments asthe test contacts and generally treat the resistor in the samemanner as the test contacts.8.2.4 Label the connectors and individual contacts therein insuch a manner that each
40、 test contact is uniquely identified.Randomly select one half of the connectors (10 connectors if20 connectors is the total sample size) to undergo wear testing,and refer to these as the “wear test samples.” Insert the otherhalf of the connectors only once at the beginning of the test andrefer to th
41、ese as the “control samples.”8.3 Methods and Procedures for Resistance Measurements:8.3.1 Prepare data sheets such that all information shown inthe sample data sheet illustrated in Fig. 2 may be recorded foreach test contact.8.3.2 Perform all electrical measurements and wear tests inthe electrical m
42、easurements laboratory discussed in Section 7.Test samples must be allowed to come to equilibrium in thisambient for a minimum of 1 h before electrical measurementsor connector insertion/withdrawal operations begin. All con-nector insertion/withdrawal operations are done with the con-nector disconne
43、cted from any power source.8.3.3 Perform all resistance measurements under dry-circuitconditions as specified in Test Methods B 539, Test Method C.In addition, use a suitable method to cancel small potentialsthat may be present in the measurement circuit. Suitablemethods are (1) measuring the resist
44、ance with the currentflowing one direction through the test contact, reversing thecurrent flow and remeasuring resistance, and averaging the tworesistance measurements; (2) measuring voltage drop acrossthe test contact with a constant d-c current flowing, measuringvoltage across the contact with no
45、impressed current, andsubtracting the second voltage from the first and using theresult to calculate resistance; or (3) measuring resistance usingan a-c method. The user shall select one method and use itthroughout the experiment.8.3.4 Make all resistance measurements in such a mannerthat the value
46、is recorded with the resolution meeting thefollowing requirements: For contacts with a measured resis-tance less than 0.100 V, record the resistance with a resolutionof 0.0001 V or better. For contacts with resistance of 0.100 Vor greater, record the resistance measurement with a resolutionof 0.1 %
47、or better. If the resistance changes during theFIG. 2 Sample Data SheetB 794 97 (2003)3measurement such that after about5sastable value of therequired resolution cannot be determined, record an estimateand note that the resistance is unstable.8.3.5 After each measurement of the reference resistor,co
48、mpare the new measured value to the initial value. If thevalues differ by more than 2 %, check the calibration of theresistance measurement instrumentation. If repair or recalibra-tion, or both, of the instrumentation is required, discard anymeasurements of test contacts made since the precedingmeas
49、urement of the reference resistor and repeat the measure-ments. If new measurements are not feasible, mark the suspectmeasurements on the data sheets.8.3.6 If the measured resistance of a contact appears unrea-sonable, appropriate investigation of possible causes is recom-mended so long as the investigation does not affect theexperiment. If the resistance in question can be traced to acause unrelated to the contact under test, the data for thatcontact may be deleted from the data set. If the cause isrepairable without affecting the experiment, repair and remea-
