Pakali pano, pali mitundu itatu ya PCB ntchito ndi mkulu-mphamvu LED kwa kutentha disipation: wamba awiri mbali mkuwa TACHIMATA bolodi (FR4), zotayidwa aloyi zochokera tcheru mkuwa bolodi (MCPCB), kusintha filimu PCB ndi zomatira pa bolodi zotayidwa aloyi.
Kutentha kwapang'onopang'ono kumagwirizana ndi mkuwa wamkuwa ndi makulidwe a chitsulo chosanjikiza ndi matenthedwe amtundu wa insulating medium. MCPCB yokhala ndi 35um yamkuwa wosanjikiza ndi 1.5mm aluminium alloy imagwiritsidwa ntchito. Flexible PCB imamatira ku mbale ya aluminiyamu aloyi. Zachidziwikire, MCPCBS yokhala ndi matenthedwe apamwamba kwambiri imakhala ndi magwiridwe antchito abwino kwambiri, koma mtengo nawonso ukukwera.
Pano, zina zatengedwa kuchokera ku chitsanzo cha MEASURING TC cha NICHIA Company monga zitsanzo zowerengera. Mikhalidwe ndi motere: LED: 3W woyera LED, chitsanzo MCCW022, RJC = 16 ℃/W. Type K thermocouple point thermometer kuyeza mutu wowotcherera kuti mutsike kutentha.
PCB mayeso gulu: awiri wosanjikiza mkuwa TACHIMATA bolodi (40 × 40mm), T = 1.6mm, mkuwa wosanjikiza dera kuwotcherera pamwamba 1180mm2, mkuwa wosanjikiza dera kumbuyo 1600mm2.
Kugwira ntchito kwa LED: IF-500mA, VF = 3.97V
TC=71℃ idayezedwa ndi mtundu wa K thermocouple point thermometer. Kutentha kozungulira TA = 25 ℃
1. TJ imawerengedwa
TJ=RJC x PD+TC=RJC (IF x VF)+TC
TJ=16℃/W(500mA×3.97V)
+71℃=103℃
2.RBA imawerengedwa
RBA=(TC-TA)/PD
=(71℃-25℃)/1.99W
=23.1℃/W
3. RJA imawerengedwa
RJA=RJC+RBA
=16℃/W+23.1℃W
=39.1℃W
Ngati TJmax yopangidwa ndi -90 ℃, TJ yowerengedwa molingana ndi zomwe zili pamwambazi sizingakwaniritse zofunikira zapangidwe. Ndikofunikira kusintha PCB ndi kutentha kwabwinoko kapena kuonjezera malo ake otenthetsera kutentha, ndikuyesa ndikuwerengeranso mpaka TJ≤TJmax.
Njira ina ndi yakuti pamene mtengo wa UC wa LED ndi waukulu kwambiri, VF = 3.65V pamene RJC = 9 ℃ / WIF = 500mA yasinthidwa, mikhalidwe ina imakhala yosasinthika, T) ikhoza kuwerengedwa monga:
TJ = 9 ℃ / W + 71 ℃ (500 ma * 3.65 V) = 87.4 ℃
Pali zolakwika pakuwerengera 71 ℃ pamwambapa, 9 ℃W LED yatsopano iyenera kuwotcherera kuti iyesenso TC (mtengo woyezedwa ndi wocheperako pang'ono kuposa 71 ℃). Zilibe kanthu. Pambuyo ntchito 9 ℃/W LED, safuna kusintha zinthu PCB ndi dera, amene akukumana ndi zofunika kamangidwe.
Kutentha kwakuya kumbuyo kwa PCB
Ngati TJmax yowerengeka ndi yayikulu kwambiri kuposa momwe zimapangidwira, ndipo mawonekedwewo salola malo owonjezera, ganizirani kumamatira PCB kubwerera ku mbiri ya "U" yopangidwa ndi aluminiyamu (kapena kupondapo mbale ya aluminiyumu), kapena kumamatira kumadzi otentha. Njira ziwirizi zimagwiritsidwa ntchito kwambiri popanga nyali zamphamvu zambiri za LED. Mwachitsanzo, mu chitsanzo chapamwambachi, sinki yotentha ya 10 ℃/W imayikidwa kumbuyo kwa PCB ndi TJ=103 ℃, ndipo TJ yake imatsikira pafupifupi 80 ℃.
Tiyenera kuzindikira apa kuti TC yomwe ili pamwambayi imayezedwa kutentha (nthawi zambiri 15 ~ 30 ℃). Ngati kutentha kozungulira kwa nyali ya LED ya TA ndi yaikulu kuposa kutentha kwa chipinda, TJ yeniyeni ndi yochuluka kuposa TJ yowerengeka yoyezedwa kutentha kutentha, kotero izi ziyenera kuganiziridwa pakupanga. Ngati kuyesa kuchitidwa mu thermostat, ndi bwino kusintha kutentha kwapamwamba kwambiri kozungulira pamene mukugwiritsidwa ntchito.
Kuphatikiza apo, ngati PCB imayikidwa mozungulira kapena molunjika, kutentha kwake kumasiyana, komwe kumakhudza muyeso wa TC. Zida za chipolopolo, kukula ndi dzenje la kutentha kwa nyali zimakhudzanso kutentha kwa kutentha. Chifukwa chake, payenera kukhala njira ina pakupanga.
Nthawi yotumiza: Mar-23-2022
