Njengamanje, kunezinhlobo ezintathu ze-PCB ezisetshenziswa nge-LED enamandla amakhulu okukhipha ukushisa: ibhodi elenziwe ngethusi elinohlangothi oluphindwe kabili (FR4), ibhodi le-aluminium esekelwe ku-aluminiyamu ebucayi yethusi (MCPCB), i-PCB yefilimu eguquguqukayo ene-adhesive ebhodini le-aluminium alloy.
Umphumela wokukhipha ukushisa uhlobene nongqimba lwethusi kanye nobukhulu besendlalelo sensimbi kanye ne-thermal conductivity ye-insulating medium. I-MCPCB enongqimba lwethusi ongu-35um kanye nengxubevange ye-aluminium engu-1.5mm ngokuvamile isetshenziswa. I-PCB eguquguqukayo inamathiselwe epuleti le-aluminium alloy. Vele, i-MCPCBS ene-thermal conductivity ephezulu inokusebenza okushisayo okuhle kakhulu, kodwa intengo nayo iyenyuka.
Lapha, enye idatha ithathwe esibonelweni se-MEASURING TC yeNkampani ye-NICHIA njengezibonelo zokubala. Izimo zimi kanje: I-LED:3W i-LED emhlophe, imodeli MCCW022, RJC=16℃/W. Thayipha ikhanda lokulinganisa lephoyinti le-thermocouple elingu-K elishiselwe kusinki wokushisa.
Ibhodi lokuhlola le-PCB: ibhodi elinezingqimba ezimbili zethusi (40 × 40mm), t = 1.6mm, indawo yongqimba yethusi yendawo yokushisela engu-1180mm2, indawo ye-copper layer of back 1600mm2.
Isimo sokusebenza se-LED: IF-500mA, VF=3.97V
I-TC=71℃ ikalwe ngohlobo lwe-thermocouple point thermometer. Izinga lokushisa le-ambient TA=25℃
1. I-TJ ibalwa
TJ=RJC x PD+TC=RJC (IF x VF)+TC
TJ=16℃/W(500mA×3.97V)
+71℃=103℃
2.RBA ibalwa
I-RBA=(TC-TA)/PD
=(71℃-25℃)/1.99W
=23.1℃/W
3. I-RJA ibalwa
I-RJA=RJC+RBA
=16℃/W+23.1℃W
=39.1℃W
Uma i-TJmax eklanyelwe ingu-90℃, i-TJ ebalwa ngokuvumelana nezimo ezingenhla ayikwazi ukuhlangabezana nezidingo zokuklama. Kuyadingeka ukushintsha i-PCB ngokukhipha ukushisa okungcono noma ukhuphule indawo yayo yokukhipha ukushisa, futhi uhlole futhi ubale futhi kuze kube i-TJ≤TJmax.
Enye indlela ukuthi uma inani le-UC le-LED likhulu kakhulu, i-VF=3.65V uma i-RJC=9℃/WIF=500mA ishintshwa, ezinye izimo zihlala zingashintshiwe, T) ingabalwa ngokuthi:
TJ = 9 ℃ / W + 71 ℃ (500 ma * 3.65 V) = 87.4 ℃
Kunephutha elithile ekubalweni okungu-71℃ ngenhla, i-9℃W LED entsha kufanele ishiselwe ukuze kuhlolwe kabusha i-TC(inani elilinganiselwe lincane kuno-71℃). Akunandaba ngempela. Ngemuva kokusebenzisa i-9℃/W LED, ayidingi ukushintsha impahla ye-PCB nendawo, ehlangabezana nezidingo zokuklama.
Usinki wokushisa ngemuva kwe-PCB
Uma i-TJmax ebaliwe inkulu kakhulu kunemfuneko yomklamo, futhi isakhiwo singavumeli indawo eyengeziwe, cabanga ukunamathisela i-PCB emuva kuphrofayela ye-aluminium enomumo othi "U" (noma isitembu sepuleti le-aluminium), noma ukunamathela kusinki wokushisa. Lezi zindlela ezimbili zivame ukusetshenziswa ekwakhiweni kwezibani ze-LED ezinamandla amaningi. Isibonelo, esibonelweni sesibalo esingenhla, usinki wokushisa ongu-10℃/W unamathiselwe ngemuva kwe-PCB nge-TJ=103℃, futhi i-TJ yayo yehla cishe ku-80℃.
Kumele kuqashelwe lapha ukuthi i-TC engenhla ilinganiswa ekamelweni lokushisa (ngokuvamile 15 ~ 30℃). Uma izinga lokushisa le-ambient lesibani se-LED TA likhulu kunezinga lokushisa legumbi, i-TJ yangempela iphakeme kune-TJ ebaliwe elinganiswa ekamelweni lokushisa, ngakho lesi sici kufanele sicatshangelwe ekuklanyweni. Uma ukuhlolwa kwenziwa ku-thermostat, kungcono ukulungisa izinga lokushisa liye ezingeni lokushisa eliphakeme kakhulu le-ambient lapho lisetshenziswa.
Ngaphezu kwalokho, noma ngabe i-PCB ifakwe ivundlile noma iqondile, izimo zayo zokukhipha ukushisa zihlukile, okunomthelela othile esilinganisweni se-TC. Izinto zegobolondo, usayizi kanye nomgodi wokushisa ukushisa kwesibani nakho kunomthelela ekushiseni kokushisa. Ngakho-ke, kufanele kube nokukhululeka okuthile ekuklanyweni.
Isikhathi sokuthumela: Mar-23-2022
