models.heat.surface_mount_package.pdf

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1、SolvedwithCOMSOLMultiphysics4.2aHeatTransferinaSurface-MountPackageforaSiliconChipIntroductionAllintegratedcircuits—especiallyhigh-speeddevices—produceheat.Intoday’sdenseelectronicsystemlayoutsheatsourcesaremanytimesplacedclosetoheat-sensitiveICs.Designersofprinted-circuitboard

2、softenneedtoconsidertherelativeplacementofheat-sensitiveandheat-producingdevices,sothatthesensitiveonesdonotoverheat.Onetypeofheat-generatingdeviceisavoltageregulator,whichcanproduceseveralwattsofheatandreachatemperaturehigherthan70°C.Iftheboarddesignplacessuchadeviceclosetoasu

3、rface-mountedpackagethatcontainsasensitivesiliconchip,theregulator’sheatcouldcausereliabilityproblemsandfailureduetooverheating.QSiliconchipInterconnectCircuitboardGroundplateVoltageregulatorFigure1:Layoutofthesimulatedsilicondevice,itspackage,andavoltageregulator.Thechipandthe

4、voltageregulatorareconnectedthroughagroundplate,apin,andtheinterconnect.Thissimulationinvestigatesthethermalsituationforasiliconchipinasurface-mountpackageplacedonacircuitboardclosetoahotvoltageregulator.Thechipissubjectedtoheatfromtheregulatorandfrominternallygeneratedheat.©20

5、11COMSOL1

6、HEATTRANSFERINASURFACE-MOUNTPACKAGEFORASILICONCHIPSolvedwithCOMSOLMultiphysics4.2aModelDefinitionThemodelisbasedonaSMDICandvoltageregulatorlayoutasinFigure1.Thesiliconchipsitsinthecenterofthepackageanddissipatesitsheattothesurroundingenvironments.Thechipalsoconnectsto

7、agroundplanethroughaninterconnectandoneofthepins.Aheatgeneratingvoltageregulatorisplacedonthesamegroundplane.Thismeansthatthevoltageregulatormayaffectthesiliconchipbytheconductedheatandthismayleadtooverheatingofthechip.Heattransfersthroughthemountedpackagetothesurroundingsthrou

8、ghconductionaccordingto:∇⋅()–k∇T=Q.Theheatsource,Q,isnegligibleinthecircuitboard,pins.andpackage,whileinthechipthismodelsetsthatparametertoavalueequivalentto20mW.Theconductivitiesofthecomponentsarechosentobesimilarto:•silicon,forthechip•aluminum,forthepins•FR4,forthepcboard•cop

9、per,forthegroundplaneandinterconnect•anarbitraryplasti