1、Designation: F1681 07aF1681 14Standard Test Method forDetermining Current Carrying Capacity of a Conductor asPart of a Membrane Switch Circuit1This standard is issued under the fixed designation F1681; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case of revision, 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 covers the determination of the current carrying capacity of a conduct
3、or as part of a membrane switch.1.2 This test method may be used to test a circuit to destruction, that is, to determine its maximum current carrying capacity,or it may be used to test the ability of a circuit to withstand a desired current level.1.3 This test method applies only to static condition
4、s, and does not apply to contact closure cycling of a membrane switch undercurrent load (test method forthcoming).1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate s
5、afety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2F1578 Test Method for Contact Closure Cycling of a Membrane SwitchF1680 Test Method for Determining Circuit Resistance of a Membrane Switch3. Terminology3.1 Def
6、initions:3.1.1 conductor resistancethe measured electrical resistance through a circuit loop between two test points.3.1.2 DiscussionWhen a switch is included in that loop, it shall be closed” in accordance with Test Method F1680.3.1.3 current carrying capacity (CCC)the maximum level of electrical c
7、urrent that a circuit can conduct without sustainingdamage.3.1.4 membrane switcha momentary switching device in which at least one contact is on, or made of, a flexible substrate.3.1.5 power capacityelectrical power is defined as current voltage = V I (watts).3.1.6 test pointstwo preselected conduct
8、ive points in a circuit loop, possibly including a switch.4. Significance and Use4.1 Current carrying capacity is used by designers and manufacturers of electronic interface circuitry to ensure that themembrane switch can reliably handle the loads occurring in normal use and under extreme circumstan
9、ces. A thoroughunderstanding of CCC allows manufacturers to take it into account when developing design rules for membrane switches.4.2 Failures due to exceeding the CCC of a circuit may take the form of a significant change in conductor resistance, insulationbreakdown (shorts), or conductor breakdo
10、wn (opens).4.3 Since a number of design parameters, such as trace width, ink film thickness, etc. and heat transfer (mounting substrates,active cooling such as fans) affect the final test results, any conclusions should only be applied to specific designs, rather than toa general combination of mate
11、rials.1 This test method is under the jurisdiction of ASTM Committee F01 on Electronics and is the direct responsibility of Subcommittee F01.18 on Membrane Switches.Current edition approved Dec. 1, 2007Jan. 1, 2014. Published December 2007January 2014. Originally approved in 1996. Last previous edit
12、ion approved in 2007 asF168107.07a. DOI: 10.1520/F1681-07A.10.1520/F1681-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on th
13、e ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users co
14、nsult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.4 Current carrying capacity tes
15、ts may be destructive and units that have been tested should be considered unreliable for futureuse.4.5 Current carrying capacity may be significantly different for static loads and dynamic (that is, cycling) loads. Failure modesare also generally different.4.6 The use of a thermocouple to monitor t
16、he temperature of the UUT may be helpful to monitor the progress of the test.4.7 Initial expected starting current should be calculated in advance to prevent damage to test equipment.5. Interferences5.1 The following parameters may affect the results of this test:5.1.1 Temperature,5.1.2 Relative hum
17、idity, and5.1.3 Barometric pressure.Heat transfer characteristics of mounting substrates,5.1.4 Active cooling,5.1.5 Imperfection or variation in conductor deposition,5.1.6 Inconsistencies in the homogeneity of the conductor.6. Hazard6.1 The user must be aware of the operating range of their equipmen
18、t to prevent damage to the device from overload duringtesting. For example, the current should be adjusted starting from a minimum setting, and a decade box should start on the highestrating.7. Apparatus7.1 Controlled current and voltage source, capable of supplying sufficient current for the range
19、in question.7.2 Suitable Meter(s), capable of measuring current and resistance (with range appropriate to the test). Do not apply a voltagegreater than the intended operating range of the circuit under test.7.3 Suitable Device, to apply a consistent, repeatable force with an elastomeric probe in acc
20、ordance with Test Method F1578to close the switch (if a switch is part of the conductor circuit being tested).7.3.1 Since the switch may heat up during the test it is advisable to use a mechanical device instead of a human finger to closethe switch.8. Procedure8.1 Pre-Test Setup:8.1.1 Turn on the po
21、wer supply; set the power supply voltage to the specified operating level and the current to the initial zerotest level.8.2 In Process Test:8.2.1 With the power supply turned off connect the test specimen to the power supply.8.2.1.1 If the specimen includes a switch close the switch in accordance wi
22、th F1680.8.2.2 Turn on the power supply and adjust the current to the initial test level. After 1 min record the actual current through thecircuit and record the applied voltage. If a thermocouple is used record the temperature at the end of each level. Record visualobservations. Record the resistan
23、ce value of the specimen (with the power supply off) or by calculation (using a volt meter acrossthe specimen).8.2.3 Adjust the power supply to the next current level, dwell for 1 min and record the current, voltage and visual observations(and temperature when applicable) as in 8.2.2. Repeat for eac
24、h additional current level.8.2.4 If the test is intended to go to destruction, and no degradation occurs at the maximum level, the test may be repeated usinga higher power (voltage and current) level, a change in the voltage range is permissible.8.2.5 At the conclusion of testing record the final re
25、sults as in 8.2.2.9. Calculations9.1 Calculate power capacity (in watts) from CCC and test voltage V as follows:P 5 CCC3V.10. Report10.1 Report the following information:10.1.1 Description and specifications of all apparatus,10.1.2 Date of test,F1681 14210.1.3 Person performing test,10.1.4 Ambient T
26、emperature,10.1.5 Relative humidity,10.1.6 Barometric pressure,10.1.7 Test voltage (dc, ac, ac-r/min, etc.),10.1.8 Test type (destructive or specified range),10.1.9 Part number, revision level and description of part under test,10.1.10 Description of test points and connection,10.1.11 Description of
27、 device and method used to close switch (if applicable),10.1.12 For each test cycle at a different current level, report the following:10.1.12.1 Current and voltage values,10.1.12.2 Description of any visual or resistance changes observed, and10.1.12.3 The user interface temperature (thermocouple),
28、if measured.10.1.13 At the conclusion of the test, report either the CCC (that is, the maximum) or whether the circuit was able to maintainthe current without discoloration or change of resistance less than the specified amount (at the desired voltage and current level)or without exceeding a tempera
29、ture of 60C at the user interface.11. Precision and Bias11.1 The precision and bias of this test method are under investigation.12. Keywords12.1 circuit resistance; current carrying capacity; membrane switch; power capacityF1681 143ASTM International takes no position respecting the validity of any
30、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 revis
31、ion at any time by the responsible technical committee and must be reviewed every five years andif not 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 co
32、mments will receive careful consideration at a meeting of theresponsible technical committee, which 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 copyrigh
33、ted 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).F1681 144
