Dust deposition on electronics modules can create unpredictible problems. Here's a method to check its level.

1. DUSTANDITSIMPACTON
ELECTRONICS
ABSTRACT
Indicatorandpreventivemaintenanceutilityfordustdepositedonelectronic/electricaldevicesand
Industrialdevicese.g.Computers.
Dustcanbeconductiveorattractmoisturecausingleakageproblems;caninsulatethedevices
causingittooverheat,cancausepoorcontactinvariouscircuitsorcancausearcingandcarbon
trackinginhighervoltageapplicationsandstillmanymoreconsequencesofdustaccumulationover
electronicscardarethere.
Dustingremainsƒveryvitalpartofpreventivemaintenanceforanykindofdigitalsystems
deployedoverƒvariedrangeandvarioustypesofindustries.Butthequestioniswhento
shutdownthesystemandstartblowingthedustwithƒblowerǤ
Thispaperfocusesononesuchsimplemethodtoindicatethedegreeofdustdepositionand
therequirementforblowingawaythedustǤ

2. INTRODUCTION
AtmosphericDustisoneoftheoldestknownenemiesofelectronicsandelectricaldevices.Over
periodoftime,gradually,dustgetsaccumulatedonthecircuitsdespitethecovered
covering/packing.
Oncontrary,whendealingwithelectronicsandelectricaldevicesthereisƒneedtokeepthedevices
cool,forwhichtherewillbeƒperforationsorgrillkindofthingengravedonthedevice
covering/canopy.Theseperforationsandgrillsonthecoveringbodygiveaneasyaccesstothedust
particletosettleonthecircuitsleadingtounexpectedconsequences.
So,inactualthereisnowayorverylesswaystosaynotodustdeposition.Goodhousekeepingis
veryessentialinensuringtheproperfunctioningofelectronic/electricaldevice.e.g.ƒPC.Thusto
ensureƒgoodproductlifeofsuchelectronicdevicestheuserneedstocarryon“Preventive
Maintenance”onregularbasis.Oneveryessentialandinitialactivityformingthebasicsof
Preventivemaintenanceis‘blowingthedustwithvacuumcleanerorƒsmallsizedairblower’.
Wedoblowinginourpersonalcomputers.Inindustriestheblowingactivityiscarriedonƒlotof
electricalpanels,controlsystem,andallthecomputershostingplantspecificcontrol,measurement
andanalysissoftware’s,duringtheirunitoutageorscheduledunitshutdownformaintenance.
Athometheblowingmaynotbeofmuchsignificancebutinindustrieslikethermalutilities,cement
industriesoroilandgasutilitiesetc...Therewillbelotofcoaldust,limestonedustandoilandgas
fumesetc…sotheneedfordustblowingactivitiesareindispensable.
Oneinterestingfactisthatthe‘rateofdustdepositionisnotinaccordancewithyourpreventive
maintenancescheduleoryourunitoutageplan’.
Now,ƒquestionwhichseemsobviousatthispartofdiscussionhowtodecidethestartofshutdown
thespecificsmallpartorcomponentfordusting/blowinginordertoensuretheavailabilityofthe
biggersystem.
Anotherquestionishowtogetanassessmentofthedegreeofdustdeposition/accumulationor
scaling.
EXISTINGTECHNIQUES
• Coveringtheelectronicscard,e.g.…plasticcoveronram.
• Intuition/experienceofthemaintenancepeople,blowingorvacuumcleaningduringannual
outages/overhaulideaaboutactualneedofit.
• senseofunusualhightemperatureofthecabinetorsystemsetc…

3. THEMETHODTOACCESSTHEDEGREEOF
DUSTONELECTRONICCARDS
Themethodinvolvestheassessmentofdustdepositiononanycircuit/cardofanyparticularsize
basedoncomparisonwithanotherreferencei.e.ƒprototypeofsamedimensionasoftheoriginal
circuit/cardwhichactsasƒreference.
Nowthisprototypeisdeployedinthesameenvironmenti.e.covering/case/canopywherethe
originalcircuit/cardlies.
Assumingthefactthattherewillbeverylittlevariationonquantityofdustdepositiononboth
(originalelectroniccard/PCBandthereferenceprototype)ofthedevicesbeingexposedtosame
environment,thusifyoucanmeasurethelevelofdustdepositiononthereferenceprototype,you
canhaveanideaofhowmuchdustisthereontheoriginaldeviceundertest.
Howtomeasurethedustaccumulationonreferenceprototypeisexplainedinthefollowingfive
stepsintheillustrationshownbelow:
Nowlet’strytocreatedustaccumulationindicatorforthisPCBintheCPUshowninthefigure
below:

4. Step1ǣIdentifythedimensionsoftheCard/PCB/Moduleundertestsothatwecanmakeƒ
referenceprototypewithsamedimensionsformeasurement.

5. Step2ǣTurnthetwooppositeEdgestotoucheachothersuchthatitformsƒcylindricalstructure.
Cylindricalstructurehastheadvantageofconsuminglessspace.

6. Step3ǣReferenceElectricalsignalmeasurement,takeanimperforatedtubeofsamedimensionas
theperforatedtubefordeterminingthemaximumvaluesoftheelectricalsignalreceivedatthe
otherendofthetube.
Step4ǣCreatingperforationsonthecylindricaltubeǤSizeofperforationwillbeinproportionto
theDustparticulatesizethatwillfurtherdependuponenvironmentoftheIndustrytypeinwhich
card/PCBisexposed.Iftheenvironmentisƒthermalutilitythenmostofthedustwillbecoaldustand
perforationsdimensionscanmatchthesizeofcoaldust.Iftheenvironmentisƒcementplantthen
perforationsdimensioncanmatchthatofcementlimestonedustansoon.

7. Step5ǣFinalstep“measurement”,justturnONtheLightsource,andobservethestrengthofthe
measuredelectricalsignalinthemeter.TheelectricalsignalwillIncrease/growwithduecourseof
thetimeasthedustaccumulatesandblocksthepores.
SincethereferenceelectricalsignalisalreadyknownfromSTEP3ǡanyfurtherriseorfallinthe
valueofmeasuredelectricalsignalwillbeƒanassessmentofdustlevel.
Nowplacethiswholeassemblyintothesameenvironmentwheretheactualelectronic
card/moduleorcircuitisplaced.
Note:Inordertoensurethattheamountdustdepositedonthecylindricaltube
1. Remainsuniformoverthecylindricalsurfaceand
2. Veryclosetotheamountofdustdepositedonactualmodule/card
Thiswholecylindricaldevicecanbemovearoundthecentralaxis(alongthelenght)withthehelp
ofƒsmallmotor.
Finallywithduecourseoftime,whengraduallydustwillbebuiltuponthemodules/cards
yourdustmonitoringkitwillassessitandgiveyouanestimationofdegreeofdust
deposition.
RESULTS/BENEFITS
Theresultsorbenefitsemergingaremanysuchasenhancedoverallproductlifeveryless
unexpectedfailuresǡfeweraccidentsduetooverheatingoftheappliancesǡimproved
performanceoftheoveralldevice,lesstripsandalarms,propercontactsisensuredforlonger
periodtimeinrelay,switchesandconnectorsetc…
Theoutputofthisdustmeasurementtransducerasdiscussedabovecanalsobeƒusedasƒtrigger
pointforanyfurtheractionoralarm.
ASSUMPTIONS
1. Dustdistributionisuniforminƒclosedenclosure/container/housinginwhich
PCB/card/moduleismounted.Thusiftwoobjectsofsamesurfaceareaareexposedto
dust/verminthedustaccumulatingonboththeobjectsaresameandsincethewhole
cylindricalassemblyisrotating,dustdistributioncanbeconsideredtobedeposited
uniformly.
2. Themethoddescribedgivesthedustindicationwithcomparisonfromƒreferencerather
anyabsolutescale.

8. 3. Themaximumthenumberofpores/holes/perforationsonthecylindricalsurface,themore
accurateisthedustlevelindication.Thetotalsurfaceareaoccupiedby
pores/holes/perforationscannotbeexactlysameasthesurfaceareaofthe
PCB/Card/Module.
4. Howmuchexactamountofdustcancauseproblemisstillunknown,themethodonly
describesƒreliablewaytoindicatethedegree,‘HI-Lo’levels,ofdustapproximately.
CONCLUSION
Themethodsurelydescribesƒmeasurementtechniquetoassessthedegreeofdustdepositiononƒ
particularmoduleorcard.
ThoughthemethodonlydescribesaboutHIandLowlevelsofdustbut

9. believethatthispaper
opensƒgatewayoffurtherpossibilitiesofanabsolutemeasurementandmorequantitative
measurementofdustdeposition.Alsothereisƒneedtoaccuratelypredicttheconsequencesof
dustǤ
AUTHORSNOTE
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AtulKumarMishra