1、Designation: F2866 11Standard Test Method forFlammability of a Membrane Switch in Defined Assembly1This standard is issued under the fixed designation F2866; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. 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 flam-mability characteristics of a membrane switch.1.2 This test method defines th
3、e MSB rating of a membraneswitch. Each character of the MSB rating represents a discretecharacteristic of a membrane switch performance under de-structive thermal loading.1.3 This test procedure will be destructive, but shouldprovide an insight into the relative performance flame-resistance characte
4、ristics of differing designs or assemblies, orboth.1.4 This test method will focus on the use of convectivecontact (burner flame) method for ignition, though othermethods of ignition are available.1.5 This test method is designed to determine if the mem-brane switch assembly will add (or detract) fr
5、om the flamepropagation from an exterior flame/fire source.1.6 If this test is intended to be used for an internalflammability source then set up the unit under test (UUT)appropriately and note it in the test scope and results.1.7 This standard does not purport to address all of thesafety concerns,
6、if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E906 Test Method for Heat and Visible Smoke R
7、eleaseRates for Materials and Products Using a ThermopileMethod3. Terminology3.1 Definitions:3.1.1 burn damagepercentage of the UUT that is dam-aged due to burn test. This is a visiual observation.3.1.2 flame propagationrefers to patterns in the flamefront that are examined (for example, uniform rat
8、e of advance,spotty ignition or charring, etc.). These observations arequalitative and should be noted in the data field.3.1.3 flame spread rate (FSR)the rate at which a flamefront travels along the surfaces of tested materials/assemblies,typically measured in mm/s or in./min.3.1.4 flame target area
9、refers to the normalized target areaof a UUT that will be used for ignition location.Any variationsshould be noted.3.1.5 flame time (Ftime) or flame enduranceamount oftime, usually in seconds, that a self-sustaining flame willendure after removal of initial ignition source before flame onUUT is exti
10、nguished.3.1.6 flame time of drippings (Ftime,drip)amount of timethat burning drippings, if any, remain burning. Typicallymeasured in seconds.3.1.7 gauze ignitionthis is a verification that UUT ignitesthe gauze.3.1.8 ignition sourcethe source that provides the heat-fluxto begin the flammability test
11、. This test method will recom-mend a convective flame for the ignition source, however, careshould be taken that any comparative tests should use the samemethod of ignition.3.1.9 mass-loss (mloss)the mass from a test specimen itlost to smoke, vaporization and char debris carried away orfallen away,
12、or both, during the flammability test cycle.Typically measured in grams (average).3.1.10 membrane switch assemblythe membrane switchshould not be tested in its unmounted state. The switch sampleshould be mounted onto the final end-use enclosure, panel,bezel, or agreed upon material.3.1.10.1 Discussi
13、onAssembly Specimen: This test methodis trying to provide a practical world analog for the resultsherein obtained. As a result, the unit under test (UUT) must inthe final mounted condition. The test is able to show flame-resistance in the final assembly as it interacts with themembrane switchs const
14、ruction.3.1.11 MSBrating to quantify the burn characteristics of amembrane switch. Each character of the MSB rating representsa discrete characteristic of a membrane switch performanceunder destructive thermal loading. (see Table 1.)1This test method is under the jurisdiction of ASTM Committee F01 o
15、nElectronics and is the direct responsibility of Subcommittee F01.18 on MembraneSwitches.Current edition approved July 1, 2011. Published August 2011. Originallyapproved in 2010. Last previous edition approved in 2010 as F2866-10. DOI:10.1520/F2866-11.2For referenced ASTM standards, visit the ASTM w
16、ebsite, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United S
17、tates.3.1.12 time-to-ignition (tign) the time to ignite UUT underthermal loading (by any ignition source selected) with aself-standing flame front on the UUT (flame on the testspecimen moving away from the thermal load source). Themethod for ignition (source) can be conductive contact (heatedfilamen
18、t), radiant energy (electrical or gas) or convective (freeflame). Typically measured in seconds.3.1.12.1 DiscussionA “perfect” incombustible materialwill have infinite time to ignition; similarly a UUT with nosustained flame within the length of the ignition exposurewould be reported as “no ignition
19、 time observed”.3.1.12.2 DiscussionUsing a convective (free flame) igni-tion source the time to ignition may be difficult to determine(due to the fact that there is interference between the ignitionsource and the ignition of the UUT).4. Significance and Use4.1 There are numerous flammability ratings
20、 and tests.Almost without fail, these standards and tests are focused onvery specific industries or results, many of which are notapplicable to the membrane switch/human machine interfaceassembly. This test is designed to provide relative resultsbetween membrane switches that have been assembled to
21、theunits final enclosure, housing, etc.4.2 In addition to the tests measurement of the rate of burn,a laboratory can also observe the effects of burning materialfalling from the test specimen onto other materials (typically agauze test area) not directly part of the test specimen. Theindirect burnin
22、g is an issue of interest to see if the testspecimen will be able to act as an initiator for a far greater andmore damaging flame event (fire). Observations should benoted, as qualitative descriptions, as appropriate.4.3 This test can measure the flammability via the use ofhigh-speed photographic or
23、 video equipment.4.4 Temperature of the ignition source can be measured viaa calibrated thermocouple pyrometer, calorimeter or IR ther-mometer with an appropriate range.4.5 This test is not designed to provide a PASS or NO PASSstatus for a switch, rather, it is designed to provide a “grade”for the l
24、evel of flammability of a membrane switch assembly(as defined in 3.1.10). The end user should make the finaldetermination if the level of flammability is acceptable for theparticular application.5. Interferences5.1 Method of IgnitionResults compared between differ-ent methods of ignition (radiant ve
25、rsus convective) mayprovide different results for tign. Therefore any comparativesamples should use the same calibrated method of ignition.5.2 Mounted in Final AssemblyMounting the membraneswitch to the end use substrate or enclosure will account for thethermal heat sink effect provided by the mount
26、ing substrate orenclosure.5.3 Rigid Fixture SupportThe membrane switch assemblyshould have rigid fixture support in order to allow remotetesting during the burn cycle. UUT should be mounted toinsure that the parts to do not fall while under test.5.4 Venting of the FPA Test BoothThe type and placemen
27、tof venting and exhausting for airflow in test booth should benoted or documented by photos or drawings, or both. Dupli-cation of test results may be achieved only with the sameamount of air-flow and air-to-fuel mixture in the test booth.5.5 Oxygen ConcentrationThe concentration of the oxy-gen in th
28、e FPA chamber atmosphere (normal air, concentratedO2, pressurized, etc.) during the test or oxidizers, or both,found in the test material(s) will affect the results.5.6 Duration of IgnitionThe longer the ignition burn testthe greater the chance the part will ignite and begin to exhibitflame propagat
29、ion.5.7 Relative Humidity in FPAIt is thought this will havesome effect on the results, however the extent of which is to bedetermined.6. Apparatus6.1 Fire Propagation Apparatus (FPA)Draft-free boothmade of non-flammable material (high-temp Pyrex, ceramic orsteel) rectangular or cylindrical space wi
30、th proper: (1) ventila-tion for exhaust fumes, smoke, etc., (2) free empty area formounting rigs and UUT and (3) appropriate fixings andmounts, as needed for ignition source and (4) vent holes orventilation, or both, for inflow of fresh air.6.1.1 FPAmay also provide oxygen in standard sea-levelnorma
31、l air concentration, 40 % oxygen, air with pure nitrogenor mixtures of gaseous suppression agents. These are alloptional and should be recorded.6.1.1.1 Example FPA Test BoothOhio State University(OSU) rate of release apparatus may be used for radiant fluxignition tests, as described below. This is a
32、 modified version ofthe rate of heat release apparatus standardized by Test MethodE906. See Fig. 1.6.2 Mounting DeviceSteel mount stand to hold measuringprobe securely and provide orthogonal (for horizontal andTABLE 1 MSB RatingModel t(ign)Time to ignition FSR Flame Spread Rate F(time)Continuation o
33、f burn m(loss)Mass loss Burn Damage % Gauze IgnitionThe following 0 = no ignition 0 = no burn 0 = self extinguishing 0 = no loss 0=0%damage 0 = noshould be 1 = 10 s 1=1mm/s 1=1s 1=10%loss 1=10%damageconsidered 2=9s 2=2mm/s 2=2s 2=20%loss 2=20%damagewhen deciding 3=8s 3=3mm/s 3=3s 3=30%loss 3=30%dama
34、geonaswitch 4=7s 4=4mm/s 4=4s 4=40%loss 4=40%damageMSBrating 5=6s 5=5mm/s 5=5s 5=50%loss 5=50%damage6=5s 6=6mm/s 6=6s 6=60%loss 6=60%damage7=4s 7=7mm/s 7=7s 7=70%loss 7=70%damage8=3s 8=8mm/s 8=8s 8=80%loss 8=80%damage9=2sorless 9=veryveryfastburn 9=9s 9=90% 9=90%ormore 9=yesF2866 112vertical) and an
35、gled (45 or defined angle from vertical)mounting of UUT with respect to ignition source. See 5.3 ifneeded.6.3 Ignition SourceTo provide the heat flux needed toinitiate flame propagation. The source may be conductive,convective or radiant and should be mounted on a swing-outstand so that the ignition
36、 source (such as a burner) may beswung out of position for warm up prior to the test under theUUT.6.3.1 Conductive Ignition SourceExample: Tungsten wirefilament, AWG #20 or greater, with proper electrical input toachieve a 3000K (4940.3F) surface temperature.6.3.2 Convective Ignition SourceExample:
37、Bunsen burnerwith a nominal 0.375 in. (9.5 mm) inside diameter tubeadjusted to give a free-standing flame 1.5 in. (38.1 mm) high.The minimum flame temperature measured by a calibratedthermocouple pyrometer in the center of the flame must be1120K (1556F).6.3.3 Radiant Ignition SourceExample: A radian
38、t heatsource incorporating four (4) Type LLsilicon carbide elements,20 in. (508 mm) long by 0.63 in. (16 mm) outside diameter.The heat source should have a nominal resistance of 1.4 V andbe capable of generating a radiant flux of $100 kW/m2,oratungsten-quartz external isolated heat element that can
39、providea radiant flux of $65 kW/m2.6.4 Photographic / Video Monitoring Equipment capableof making visual recording of the burn test. A calibration stripor grid should be mounted in the visual focal plane so that therate of flame advance or flame spread-rate, (flammability) canbe measured in mm/s or
40、in./min.6.5 Timing DeviceStop watch or other timing device inseconds or minutes of elapsed test time for UUT. It must beused to measure the time of application of burner flame to UUTand self-extinguishing time or test duration, or both.6.6 Temperature Measuring Device, radiant flux meter,calorimeter
41、, thermocouple pyrometer or IR pyrometer of suit-able ranges, as required depending on ignition source set upused.6.6.1 Thermocouple PyrometersThermocouples suitablefor testing the thermal output of the ignition flame. Theseshould be 0.0625 in. (1.6 mm) to 0.125 in. (3.18 mm) metalsheathed, ceramic
42、packed, type K, grounded thermocoupleswith a nominal 22 to 30 AWG conductors.6.6.2 CalorimeterCalorimeter must be a 0-17.0 W/cm2(0-15.0 BTU/ft2-s) calorimeter, accurate to within 63%.6.7 Data RecordingSuitable calibrated instrument with anappropriate range to measure and record the outputs of thecal
43、orimeter and thermocouples.6.8 Weight ScaleWeighing device, capable of measuringthe mass (weight) of the UUT. The part may be weighed beforeand after flammability test or a continual weighing system maybe used to provide real-time mass changes during test. Thescale should be accurate to 61g.6.9 Gauz
44、eCotton, a supply of (absorbent) 100 % un-treated cotton. First Aid Steri Pad (4 by 4 in. 12 ply sterile 100% cotton pad constructed of fine mesh USP Type VII gauze).7. Procedure7.1 Pre-Test Setup:7.1.1 Precondition membrane switch assembly until ap-proximation of steady-state condition is achieved.
45、 UTT mustbe conditioned at 77 6 20F (25 6 10C) 55 % 6 10relative humidity for a minimum of 24 h before testing. UUTshall remain in this conditioned state up to being placed in FPAfor flammability testing.7.1.2 Weigh UUT just prior to test.7.1.3 Calibrate ignition source with NIST traceable measur-in
46、g devices, as appropriate: radiant flux meter, calorimeter,thermocouple pyrometer or IR pyrometer.7.1.4 Ensure that the test specimen (unit under test, UUT) ismounted securely onto the rigid substrate or enclosure usingthe same manner and material(s) of attachment representativeof the final product.
47、 The entire assembly should then besecurely fixed into position by means of nonflammable clampsor spring grips.7.1.4.1 Vertical TestUUT should be mounted verticallyabove ignition source; see Fig. 2.7.1.4.2 Horizontal TestUUT should be mounted horizon-tally (90 orthogonal plane) directly above igniti
48、on source; seeFig. 3.FIG. 1 Typical FPA Test BoothF2866 1137.1.4.3 Angle TestUUT should be mounted at the definedangle from the direction of the ignition source; see Fig. 4. Allangles are approximate.7.1.5 Clamp UUT in test fixture and position desired.7.1.6 Position test Bunsen burner under center
49、of the des-ignated flame target area of UUT switch assembly (X-Ylocation). Burner is in “off” (cold) state.7.1.7 Position Bunsen burner at the appropriate height(Z-direction) under flame target area of the UUT. Burner is in“off” (cold) state.7.1.8 Swing the Bunsen burner out of position from underUUT and ignite. Burn for approximately 2 min to allow it tocome up to steady state.NOTE 1Calorimeter should read 11.9 6 0.6 W/cm2(10.5 6 0.5BTU/ft2-s). Thermocouple should read 1556 6 36F.7.1.9 Position clean white gauze below UUT for t
