A halin yanzu, akwai nau'ikan PCB guda uku da aka yi amfani da su tare da LED mai ƙarfi don ɓarkewar zafi: allon taɓawa mai gefe biyu na yau da kullun (FR4), alloy na tushen m jan ƙarfe (MPCCB), PCB mai sassauƙa tare da manne akan allon alloy na aluminum.
Sakamakon zafi na zafi yana da alaƙa da Layer na jan karfe da kauri na ƙarfe na ƙarfe da ƙarancin zafi na matsakaicin insulating. MCPCB tare da 35um jan karfe Layer da 1.5mm aluminum gami ana amfani da gabaɗaya. PCB mai sassauƙa yana manne da farantin alloy na aluminum. Tabbas, MCPCBS tare da high thermal conductivity suna da mafi kyawun aikin thermal, amma farashin kuma yana tashi.
Anan, an ɗauki wasu bayanai daga misalin MEASURING TC na Kamfanin NICHIA a matsayin misalan lissafi. Sharuɗɗan sune kamar haka: LED: 3W farin LED, samfurin MCCW022, RJC = 16 ℃ / W. Nau'in K ma'aunin zafi da sanyio na ma'aunin zafi da sanyio mai auna kai wanda aka yi masa walda don nutsewar zafi.
PCB gwajin jirgin: biyu-Layer jan karfe mai rufi jirgin (40×40mm), t = 1.6mm, jan karfe Layer yanki na waldi surface 1180mm2, Tagulla Layer yanki na baya 1600mm2.
Matsayin aiki na LED: IF-500mA, VF = 3.97V
TC=71℃ an auna shi da nau'in K thermocouple point thermometer. Yanayin zafin jiki TA = 25 ℃
1. Ana lissafin TJ
TJ=RJC x PD+TC=RJC (IF x VF)+TC
TJ=16℃/W(500mA×3.97V)
+71℃=103℃
2.RBA ana lissafta
RBA=(TC-TA)/PD
= (71 ℃-25 ℃)/1.99W
= 23.1 ℃/W
3. Ana lissafin RJA
RJA=RJC+RBA
=16℃/W+23.1℃W
= 39.1 ℃W
Idan tsara TJmax ne -90 ℃, da TJ lasafta bisa ga sama yanayi ba zai iya saduwa da zane bukatun. Wajibi ne a canza PCB tare da mafi kyawun zubar da zafi ko ƙara yawan zafin zafi, da gwadawa kuma sake ƙididdigewa har zuwa TJ≤TJmax.
Wata hanya ita ce lokacin da darajar UC na LED ya yi girma, VF = 3.65V lokacin da aka maye gurbin RJC = 9 ℃ / WIF = 500mA, sauran yanayi ba su canzawa, T) za'a iya ƙididdige su kamar:
TJ = 9 ℃ / W + 71 ℃ (500 ma * 3.65V) = 87.4 ℃
Akwai wasu kurakurai a cikin lissafin 71 ℃ a sama, sabon 9 ℃W LED ya kamata a welded don sake gwada TC (ƙimar da aka auna ta ɗan ƙasa da 71 ℃). Ba komai. Bayan amfani da 9 ℃ / W LED, ba ya buƙatar canza kayan PCB da yanki, wanda ya dace da buƙatun ƙira.
Tushen zafi a bayan PCB
Idan TJmax da aka ƙididdige ya fi girma fiye da abin da ake buƙata na ƙira, kuma tsarin ba ya ƙyale ƙarin yanki, yi la'akari da manne PCB zuwa bayanin martabar aluminum mai siffar "U" (ko tambarin aluminium), ko mannewa ga matattarar zafi. Ana amfani da waɗannan hanyoyin guda biyu a cikin ƙirar fitilun LED masu ƙarfi da yawa. Misali, a cikin misalin lissafin da ke sama, ana manna kwandon zafi na 10 ℃/W a bayan PCB tare da TJ = 103 ℃, kuma TJ ɗinsa ya faɗi zuwa kusan 80 ℃.
Ya kamata a lura a nan cewa ana auna TC na sama a dakin da zafin jiki (yawanci 15 ~ 30 ℃). Idan yanayin zafin yanayi na fitilar LED TA ya fi yawan zafin jiki, ainihin TJ ya fi girma fiye da TJ da aka auna a dakin da zafin jiki, don haka ya kamata a yi la'akari da wannan factor a cikin zane. Idan an gudanar da gwajin a cikin ma'aunin zafi da sanyio, yana da kyau a daidaita zafin jiki zuwa mafi girman yanayin yanayi lokacin amfani.
Bugu da ƙari, ko an shigar da PCB a kwance ko a tsaye, yanayin zafi na zafi ya bambanta, wanda ke da wani tasiri akan ma'aunin TC. Kayan harsashi, girman da ramin zubar da zafi na fitilun kuma suna da tasiri akan zubar da zafi. Saboda haka, ya kamata a sami wasu lebe a cikin zane.
Lokacin aikawa: Maris 23-2022
