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1、如何计算散热器的散热功率CalculationCornerEstimatingParallelPlate-FinHeatSinkThermalResistanceRobertE.Simons,AssociateEditor,IBMCorporationAsnotedpreviouslyinthiscolumn,thetrendofincreasingelectronicmodulepowerismakingitmoreandmoredifficulttocoolelectronicpackageswithair.Asaresultthereareanincreasingnumb
2、erofapplicationsthatrequiretheuseofforcedconvectionair-cooledheatsinkstocontrolmoduletemperature.AnexampleofawidelyusedtypeofheatsinkistheparallelplateconfigurationshowninFigure1.Figure1.Parallelplatefinheatsinkconfiguration. Inordertoselecttheappropriateheatsink,thethermaldesignermustfi
3、rstdeterminethemaximumallowableheatsinkthermalresistance.Todothisitisnecessarytoknowthemaximumallowablemodulecasetemperature,Tcase,themodulepowerdissipation,Pmod,andthethermalresistanceatthemodule-to-heatsinkinterface,Rint.Themaximumallowabletemperatureattheheatsinkattachmentsurface,Tbase,is
4、givenbyThemaximumallowableheatsinkresistance,Rmax,isthengivenbywhereTair-in,isthetemperatureofthecoolingairattheinlettothe heatsinkpassages.Atthispointmanythermalengineerswillstartlookingatheatsinkvendorcatalogs(ormorelikelytodaystartsearchingvendorsontheinternet)tofindaheatsinkthatwillfitin
5、theallowablespaceandprovideaheatsinkthermalresistance,Rhs,lessthanRmaxatsomespecifiedflowrate.Insomecases,itmaybeusefultodoasizingtoestimateRhsforvariousplate-finheatsinkdesignstodetermineifafeasibledesignconfigurationispossible.Theremainderofthisarticlewillprovidethebasicequationstodothis.T
6、hethermalresistanceoftheheatsinkisgivenbywherehistheconvectiveheattransfercoefficient,Abaseistheexposedbasesurfaceareabetweenfins,Nfinisthenumberoffins,finisthefinefficiency,andAfinisthesurfaceareaperfintakingintoaccountbothsidesofthefin. Toproceedfurtheritisnecessarytoestablishthemaximu
7、mallowableheatsinkvolumeintermsofwidth,W,height,H,andlengthintheflowdirection,L.Itisalsonecessarytospecifyafinthickness,tfin.Usingtheseparametersthegap,b,betweenthefinsmaybedeterminedfromTheexposedbasesurfaceareamaythenbedeterminedfromandtheheattra
