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基于热电分离式设计理念,将AlN陶瓷片金属化后作为微散热器嵌入FR4材料内形成了复合散热基板。采用电镜扫描、光学显微,通过冷热循环冲击试验对FR4与AlN两相界面处在高低温突变情况下的界面形貌进行了分析。利用ANSYS软件对基板进行了仿真热模拟,研究了AlN嵌入后FR4导热性能的变化规律。利用结温测试仪、功率计和半导体制冷温控台等仪器设备,通过结温测试对比研究了该复合散热结构与金属芯印刷电路板(MCPCB)对大功率LED封装散热效果的影响。结果表明,该复合散热基板在经低温-55℃,高温125℃,1 000个冷热循环后,FR4和AlN界面无剥离现象发生,在环境温度急剧变化的条件下结合力良好。同时,FR4在嵌入AlN之后,导热性能得到了明显改善,且与MCPCB相比,能更有效降低LED芯片结温。
Based on the design concept of thermoelectric separation, the AlN ceramic sheet is metallized and embedded into the FR4 material as a micro heat sink to form a composite heat dissipation substrate. The morphology of the interface between the FR4 and AlN interfaces at high and low temperature was analyzed by scanning electron microscopy and optical microscopy. The thermal simulation of the substrate was carried out by ANSYS software. The thermal conductivity of FR4 after AlN insertion was studied. The effects of the composite cooling structure and MCPCB on the heat dissipation of high power LED package were studied by the junction temperature test using the instruments such as junction temperature tester, power meter and semiconductor refrigeration temperature controller. The results show that there is no stripping of the interface between FR4 and AlN after the low temperature of -55 ℃, high temperature of 125 ℃ and 1000 cycles of cooling and heating. The bonding strength is good under the condition of rapid change of ambient temperature. At the same time, FR4 significantly improved the thermal conductivity after AlN was embedded, and compared with MCPCB, it can effectively reduce the LED chip junction temperature.