热分析的基本参数与概念

1、ProjectnameProjectnumberAuthorReleaseDepartmentFilenameCreationdateExecutiveSummaryTableofContents1 Introduction31.1 基本参数介绍32 Activities42.1 Theta-ja(Junction-to-Ambient42.1.1 测量方法42.1.2 节温计算公式62.2 Theta-jc(qc)Junction-to-Case62.2.1 测量方法62.2.2 节温计算公式62.2.3 亚与ja的关系72.3 Theta-jb(qb)Junction-to-Board72

2、.3.1 测量方法82.3.2 节温计算公式82.3.3 .与ja的关系82.4 W的含义92.4.1 Wjb92.4.2 Wjc92.5 各种封装的散热效果92.5.1 TIPowerPAD封装的使用注意事项103 Results123.1 关于.ejcJ乎jt使用问题124 Discussion124.1 热仿真软件的使用125 Conclusions125.1 126 Abbreviations,Definitiones,Glossary136.1 137 Version131Introduction1.1基本参数介绍般包括三个参数0ja.jC,Qb,三种参数所指的散热图示如下Ta,Tb

3、,Tc的测试点如下：TIteFiH汨and丁丫加加HeatF/owSolder-80%ofheatLorTpTa(ambientair)Tc。L一L1%ofheat/-20%ofheattV。已5andTtpicmHeatF加hSolderdivide。bvtctllhentiiippower佛)：applicabletoannYed-comecticpackagesTtietbeniin)e-ironmentniustbespecified.氏Rej：Jiuicrion-toCaseThenrulResistance8rsMK7WJunction-To-CaseThcnnEResistanc

4、ewithheatflowThioufhpAcknzeborrom6JrtopSjCwpKWJunction-to-CaseThenmlResiEitanctwithheatflowthroughpackagetop肌KWJuncticn-toTluidThenralResistance牝KLMJunction-to-LeadThemnRehitanice由KWJuncticn-to-LeadThenmCfcaractezarionParmieterAthem疝metrederivedfrsrntjiedfferefleeinjunctiontemperitixpe(Tj)lendTl)div

5、idertr，tetaihetinpover(Pn);applkablemostly邨kadtddevicepackage;.Tlwthemialtnusigtp?cifidSjMARsthaK7WJiuictioQ-to-lIoiigAirTherm】ResistanceG;rReJtKM，Juuctica-lo-RcfcrcnccTiiciuialRjcsaitaiiccsKNJimction-to-TapThermalClaaractenzaticmParameter.AthmnalmetncdnnTtlfioinIlirddGfeicnceinjunctiontcmpnatuzE(Tj

6、)andpackagetoptenipm.cure(Tj)-ividecbvtctalheatingpower(Ph)-Thethemudriivircmmentmustbespccifird.陛rxKMJimctiGQ-to-defmedpoin(X)TheirnaKesistance2Activities2.1 Theta-ja(Qa)Junction-to-Ambientpn节到空气的热阻。单位c2.1.1测量方法/WoThemeasurementof6isperformedusingthefollowingsteps(summarizedfromEIA/JESD51=1):Step1A

7、partusuallyaninteiiratedcircuitdCpackagecontainingathermaltestchipthatcanbothdissipatepowerandmeasurethernaximumchiptemperature,ismountedonatestbo白rdStepZThetemperaturesensingcomponentofthetestchipiscalibrated.Step3一Thepackage/testboardsystemisplacedineitherastiIairormovingairIaJenvironment.Step4.Ak

8、nownpowerisdissipatedinthetestchip.Step5、AftersteadystateIsreached,thejunctiontemperatureismeasured.Step6ThedifferenceinmeasuredambianttemperaturecomparedtothemeasuredjunctiontemperatureiscalculatedandIsdividedbythedissipatedpov.ergivingavaluefore,incCjW.DTItoaMkctevl器件说明书中的JA是根据JESD51标准给出的，其标准环境是指将

9、器件安装在较大的印刷电路板上，并置于1立方英尺的静止空气中。&与PCB叠层结构、芯片焊盘大小、高度等均有关系，故因此说明书中的数值（实验室数据）没有太大的参考价值。但目前只能如此计算。2.1,2节温计算公式TjunctionTambient:Tjunction:Power:=Tambient+(ja*Power)；环境温度芯片PN节温度芯片消耗功率2.2 Theta-jc(9=)Junction-to-Case0jc是结到管壳的热阻，管壳可以看作是封装外表面的一个特定点。此参数最是为预估有散热器的器件设计的。2.2.1 测量方法Summarized,theprocedureis:StepLAn

10、ICpackagenormallycontainingathermaltestchipismountedonateslPCB.whichisnormallyihe1sJEDECdefinedtestboardStep2.ThepackageispressurefitinadeadbugconfigurationtnaCjcoldplate(aCublock.vithcircuitingconstanttemperaturefluid；whenthetopofthecaseistobemeasured.Otherwise,3Cucoldplatecontacttothebottomofthepa

11、ckageisprovidedthroughthePCBwhentheprimarycoolingpathofthepackageisthrough口solderedplateintothePCB.Step3.Siliconethermalgreaseorotherthermalinterlacematsnalprovidesthermalcouplingbet/jeenthecoldplateandpackage.Step4InsulationisprovkiedaroundtheteslcoupontcminimizeparasiticheatkssStep5.Powerisapplied

12、tothedevice.Step6.Thejunctiontemperatureofthetestchipismeasured.Slep1Thelemperatureofthepackagesurfaceinconlactwiththecoldp匕悔&measuredbyathermocoupleorothertemperaturesensorpre-ssedagainstthissurfaceStep88、iscalculatedbydividingtfiemeasuredtemperaturedeltabyttiedissipatedpow&r.IPiermoccupteFigure4.C

13、uColdPlateMeasurementProcess2.2.2 节温计算公式Tjunction=Tcase+(c*Power)Tcase:芯片外壳温度Tjunction：芯片PN节温度Power:芯片消耗功率一般有散热片的情况下计算公式：Tjunction=Tambient+i1也+联+隹a)*Power)s:芯片外壳到散热片的热阻也a：散热片到空气的热阻Tambient：环境温度Tjunction:芯片PN节温度Power:芯片消耗功率其中Qs的计算公式如下：2.3 丁仃日制YS用JThebestrTititliudfuitdlculalirigR”isioJLtLiallyrnidsu

14、ieIlievauebulifIhisisnotpussible.tqjJhji.LJI】。一uj1t:；，一n、二t已Ty.Nl：l山工tIf二i二fe七、-nL.mjte匚1匚tilth.：rnamtu-fjxulresistanceihatcanbdevelopedbetweendruytwosurfdcisisneglected.UgktAWhereT=Thethicknessofinterfacelayerbetweenpackageandheaisinkk二ThebulkthermalconductivityofthetiiermalinterfacenateralA-Theare

15、aoverwhicfithedermalinteifacematerialts洋plied2.2.3%与9a的关系亦可认为存在如下公式生19c+Qa)2.3Theta-jb(00Junction-to-Board是指从结到电路板的热阻，它对结到电路板的热通路进行了量化。备通常的测量位置在电路板上靠近封装处，即L1节图表所示。2.3.1测量方法4.1曳Measurenient期的。dTheprimarymethodtomeasuna与isasfollowsSl/p1.Alest(JMkgeoonlainiityaDermaltestdisisinauntedwimleslbu/d.Slep2At

16、mewirethermocouple(36-40gauge)isgluedorsolderedtothedevicep(ndosesitothediip.Intriecm/ofBGApiKkdgts,山匕thefiTiocuupnitsolderfdcrglu旬to(tieli冥号exlinfromnricrrhepar匕力gedgetti甫i$ctoscsttothechipStep3.Theboardisclampedinabpet.iddoubkcoldplait?fixturewithirmJdliixibt?tweenthepackage由府rhecoldplatesurfacesr

17、butwithihcrmalconmdbetweenthe8klptaieandtheboard.TheeddplalehealsinkstiePCB.Step4,Powerisdissipatedmmedie.Slep5.Theteriperalur&sofIbedieand尸。aremonitored.SipnWhen工tntf1与nrbiipvprtthpdetrbeTwrrnthenrtinnandpin，产eymturm*iqdividedbythelotlpowerThisptocedureisdefinedmorepredselvinEIA/JESD51SGootaminCooh

18、nlOutLeadTlermocDUpleFigurt7.fltMeasurementMethod2.3.2 节温计算公式Tjunction=Tpcb+(fjb*Power)TPCB:PCB处温度Tjunction:芯片PN节温度Power:芯片消耗功率2.3.3 %与格的关系亦可认为存在如下公式如寸jc+ebb+eba)ThemalPathr.AmbientLTCase(topofpackage二JunctionTJ-1(Heatgeneration)JAaOjRBoardbottomofpackage)BOZd(edgeofboard)AmbientNote:Intheequivalent

19、electricalcircuitPower(W)=Currant(ATemperature(CorK)=VoltageDrop(V)ThermalResistance(C/W)=Resistance(1)AT=PistheequivalentofAV=IR1.4 的含义乎和e之定义类似，但不同之处是于是指在大部分的热量传递的状况下，而e是指全部的热量传递。在实际的电子系统散热时，热会由封装的上下甚至周围传出，而不一定会由单一方向传递，因此于之定义比较符合实际系统的量测状况。1.4.1 咖TJ配结到电路板的热特性参数，单位是/Wo热特性参数与热阻是不同的。与热阻ejb测量中的直接单通路不同，T

20、JB测量的元件功率通量是基于多条热通路的。由于这些WJB的热通路中包括封装顶部的热对流，因此更加便于用户的应用。Tjunction=Tpcb+(阴b*Power)1.4.2 WjcTjunction=Tcase+(Wjc*Power)(此时不能加散热片)1.5 各种封装的散热效果PeiibnnanceofTypicalThennalSolutionsThermalSolutions由图可见，BGA封装的散热效果最佳。2.5.1TIPowerPAD封装的使用注意事项IntorUkilofJFrPlanoG7bormal晒口Area。&JnoAB-lcnodMQd心熊京，一一eOAunnE-n6=QUR-l加，fflun-PZB切切flMuedkn&二切In兽善一/*禽7一！uhtp，jaq石s*舌/q_!q9uLJa,JBFH-1立昌FE2恪二金七3G0s口瞿Dmuto_XI=L6(QJ到ONa邑工duao电KIF&L-CEL:ggQ%.JiddnQ.口石EQKO$OJUXJUlJEdBlm$ul.QJLDrw-口加0E&GD仁而但WDlqal邑=5-E6pusdapXJX&E-:-;MU二-:-,.二二L至Bp息8言七。15LIJ9+po_i01kc-bl-HLE50,雷旨LI.口R*urMdc-rd上d寸ll_JEDEC2-LAYERBOARDTHERMALRESI