Tam sim no, muaj peb hom PCB siv nrog high-power LED rau tshav kub dissipation: zoo tib yam ob-sided tooj liab coated board (FR4), txhuas alloy raws li rhiab tooj liab board (MCPCB), hloov tau zaj duab xis PCB nrog nplaum ntawm txhuas alloy board.
Lub tshav kub dissipation nyhuv muaj feem xyuam rau cov tooj liab txheej thiab thickness ntawm cov hlau txheej thiab thermal conductivity ntawm insulating nruab nrab. MCPCB nrog 35um tooj liab txheej thiab 1.5mm aluminium alloy feem ntau yog siv. Flexible PCB yog glued rau aluminium alloy phaj. Tau kawg, MCPCBS nrog cov thermal conductivity muaj qhov zoo tshaj plaws thermal kev ua tau zoo, tab sis tus nqi kuj nce.
Ntawm no, qee cov ntaub ntawv raug coj los ntawm qhov piv txwv ntawm MEASURING TC ntawm NICHIA Company ua piv txwv suav. Cov xwm txheej muaj raws li hauv qab no: LED: 3W dawb LED, qauv MCCW022, RJC = 16 ℃ / W. Hom K thermocouple point tus pas ntsuas kub ntsuas lub taub hau welded rau lub dab dej kub.
PCB xeem board: ob txheej tooj liab coated board (40 × 40mm), t = 1.6mm, tooj liab txheej cheeb tsam ntawm vuam nto 1180mm2, tooj liab txheej cheeb tsam ntawm rov qab 1600mm2.
LED ua haujlwm raws li txoj cai: IF-500mA, VF = 3.97V
TC = 71 ℃ yog ntsuas nrog hom K thermocouple point tus pas ntsuas kub. ambient kub TA = 25 ℃
1. TJ yog xam
TJ = RJC x PD + TC = RJC (IF x VF) + TC
TJ = 16 ℃ / W (500mA × 3.97V)
+71 ℃ = 103 ℃
2.RBA yog xam
RBA = (TC-TA)/PD
= (71 ℃ - 25 ℃) / 1.99 W
= 23.1 ℃ / W
3. RJA yog xam
RJA = RJC + RBA
= 16 ℃ / W + 23.1 ℃ W
= 39.1 ℃ W
Yog tias tus tsim TJmax yog -90 ℃, TJ xam raws li cov xwm txheej saum toj no tsis tuaj yeem ua tau raws li cov qauv tsim. Nws yog ib qho tsim nyog los hloov PCB nrog cov cua kub zoo dua los yog ua kom nws cov cua sov ntau dua, thiab sim thiab suav dua kom txog thaum TJ≤TJmax.
Lwm txoj hauv kev yog tias thaum UC tus nqi ntawm LED loj dhau, VF = 3.65V thaum RJC = 9 ℃ / WIF = 500mA hloov, lwm yam kev hloov pauv tsis hloov, T) tuaj yeem suav tau raws li:
TJ = 9 ℃ / W + 71 ℃ (500 ma * 3.65 V) = 87.4 ℃
Muaj qee qhov yuam kev hauv kev suav ntawm 71 ℃ saum toj no, tshiab 9 ℃ W LED yuav tsum tau welded rau rov kuaj TC (tus nqi ntsuas me ntsis tsawg dua 71 ℃). Nws tsis muaj teeb meem tiag tiag. Tom qab siv 9 ℃ / W LED, nws tsis tas yuav hloov cov khoom siv PCB thiab cheeb tsam, uas ua tau raws li cov qauv tsim.
Kub dab dej nyob tom qab ntawm PCB
Yog tias qhov ntsuas TJmax loj dua li qhov tsim nyog, thiab cov qauv tsis tso cai rau thaj tsam ntxiv, xav txog kev ua kom lub PCB rov qab mus rau "U" zoo li txhuas profile (lossis txhuas phaj stamping), los yog ua rau lub dab dej kub. Ob txoj kev no feem ntau yog siv rau hauv kev tsim ntau lub zog LED teeb. Piv txwv li, hauv qhov piv txwv saum toj no, lub dab dej kub 10 ℃ / W tau muab tso rau sab nraum qab ntawm PCB nrog TJ = 103 ℃, thiab nws TJ poob mus txog 80 ℃.
Nws yuav tsum raug sau tseg ntawm no tias TC saum toj no ntsuas ntawm chav tsev kub (feem ntau 15 ~ 30 ℃). Yog tias qhov kub thiab txias ntawm LED teeb TA yog siab dua li chav tsev kub, qhov tseeb TJ siab tshaj qhov ntsuas TJ ntsuas ntawm chav tsev kub, yog li qhov no yuav tsum tau xav txog hauv kev tsim. Yog tias qhov ntsuas tau ua tiav hauv qhov ntsuas kub, nws yog qhov zoo tshaj plaws los kho qhov kub thiab txias mus rau qhov kub siab tshaj plaws thaum siv.
Tsis tas li ntawd, txawm hais tias PCB tau teeb tsa kab rov tav lossis ntsug, nws cov cua sov dissipation yog txawv, uas muaj qee yam cuam tshuam rau TC ntsuas. Cov khoom siv plhaub, qhov loj me thiab qhov kub ntawm lub qhov hluav taws xob ntawm lub teeb kuj muaj kev cuam tshuam rau cov cua sov dissipation. Yog li ntawd, yuav tsum muaj qee qhov leeway hauv kev tsim.
Post lub sij hawm: Mar-23-2022
