氮化铝—铝复合封装基板

发布时间：2018-07-11 09:53

  本文选题：LED散热 + COB封装　； 参考：《湖北大学》2014年硕士论文

【摘要】：应用于照明领域的LED功率不断提高,其散热问题日益突出,开发新的封装方式与散热材料成为LED照明技术的核心问题。Chip on Board (COB)封装因具有更小的热阻而成为一种极具潜力的封装形式。高可靠性的COB封装基板必须具有高热导率、高绝缘性及与芯片匹配的热膨胀系数TEC；当应用于LED封装时,为了获得高出光率,封装基板需兼具高反射率。 目前应用于封装的基板材料主要有金属与陶瓷。金属基板中镜面铝虽具有高热导率与高反射率,然而其TEC失配与绝缘性问题导致其可靠性较差。陶瓷材料中氮化铝(A1N)各方面性能优越,但成本高,加工困难。基于陶瓷绝缘层的金属基板(IMS)因结合了金属与陶瓷的优点而受到关注,例如Al-AIN基板：高热导率、绝缘性与反射率。然而由于与A1N之间热膨胀系数差异大,结合强度不高,高速率沉积A1N困难,而使得该技术未能有效应用。为了获得高绝缘、高导热、热膨胀系数匹配及高反射率的铝基封装基板,本文主要做了以下几项工作： 1)利用磁控溅射制备A1N薄膜。在真空环境下,磁控溅射法能够高速率沉积A1N薄膜,在现有数据资料的条件下,通过多次的实验,并对薄膜的电学性能,膜厚、结晶态进行了测试、分析,最终寻找到了最佳的实验条件：工作气压0.2Pa,氮氩比为1：1,溅射功率200W。 2)为了解决A1N与金属铝基结合强度差的问题,对金属铝进行阳极氧化预处理。在对氧化膜的膜厚、电学性能分析后,得到了阳极氧化膜膜厚、电阻率、击穿电压与氧化时间与环境温度的关系。 3)为了制备高绝缘、高导热、热膨胀系数匹配及高反射率的金属基板,在对金属铝基预处理后,利用磁控溅射在铝基上沉积氮化铝薄膜。在不同实验参数下制得的金属基板在结合力、电阻率、击穿电压、抗热冲击等方面的性能存在差异。为了能够应用在实际生产,需要在低成本的前提下,选择性能最佳的实验参数：金属铝基底阳极氧化4h后,在工作气压0.2Pa,氮氩比为1：1,溅射功率200W的条件下溅射氮化铝30min。 本文通过磁控溅射制备高抗电强度的A1N薄膜,在非晶薄膜中抗电强度达到700V/um。在铝基底上沉积A1N之前,采用阳极氧化对镜面抛光的铝基底进行预处理,有效缓解了由A1N与A1之间TEC失配导致的A1N膜破裂的问题,同时提高了A1N薄膜与Al基底的结合强度。 实验制得的复合基板阳极氧化铝膜厚度为10um,氮化铝膜lum时,耐压值超过1350V,绝缘电阻率为1.7x106AIN薄膜与基底结合强度大于8Mpa；在260℃热冲击下,基板未发生形变,氮化铝膜未破裂,电学特性无明显变化。
[Abstract]:The power of LED used in lighting field is increasing, and the problem of heat dissipation is becoming more and more serious. The development of new packaging methods and heat dissipation materials has become the core problem of LED lighting technology. Chip on Board (COB) packaging has become a potential packaging form because of its smaller thermal resistance. The high reliability COB packaging substrate must have high thermal conductivity, high insulation and thermal expansion coefficient matching with the chip. When used in LED packaging, the packaging substrate must have high reflectivity in order to obtain high luminous rate. At present, the main substrate materials used in packaging are metals and ceramics. Although the mirror aluminum in the metal substrate has high thermal conductivity and high reflectivity, its TEC mismatch and insulation lead to poor reliability. Aluminum nitride (A1N) has excellent properties in ceramic materials, but its cost is high and it is difficult to process. Metal substrate (IMS) based on ceramic insulator has attracted much attention because of its advantages of combining metal with ceramics, such as Al-AIN substrate: high thermal conductivity, insulation and reflectivity. However, due to the large difference of thermal expansion coefficient with A1N, the low binding strength and the difficulty of high rate deposition of A1N, the technology can not be applied effectively. In order to obtain high insulation, high thermal conductivity, thermal expansion coefficient matching and high reflectivity aluminum based packaging substrate, the main work of this paper is as follows: 1) A1N thin films are prepared by magnetron sputtering. In vacuum environment, magnetron sputtering can deposit A1N thin films at a high rate. Under the condition of available data, the electrical properties, film thickness and crystalline state of the films are tested and analyzed through many experiments. Finally, the optimum experimental conditions were found: working pressure 0.2 Pa, ratio of nitrogen to argon 1: 1, sputtering power 200W.2) in order to solve the problem of poor bonding strength between A1N and aluminum, anodic oxidation pretreatment of metal aluminum was carried out. After analyzing the film thickness and electrical properties of the oxide film, the relationship between the thickness, resistivity, breakdown voltage and oxidation time and ambient temperature of the anodic oxide film is obtained. 3) in order to prepare high insulation and high heat conduction, the anodic oxide film thickness, resistivity, breakdown voltage and oxidation time are obtained. Aluminum nitride thin films were deposited on aluminum substrates by magnetron sputtering after pretreatment of metal substrates with matching thermal expansion coefficient and high reflectivity. The properties of the metal substrate fabricated under different experimental parameters are different in terms of adhesion, resistivity, breakdown voltage, thermal shock resistance and so on. In order to be used in practical production, the best experimental parameters should be selected on the premise of low cost: after anodizing of metal aluminum substrate for 4 hours, the working pressure is 0.2 Pa, the ratio of nitrogen to argon is 1: 1, the sputtering power is 200 W, and the sputtering power is 200 W for 30 min. A1N thin films with high electrical resistance were prepared by magnetron sputtering. The electrical resistance of A1N thin films in amorphous films was 700 V / m ~ (um). Before the deposition of A1N on the aluminum substrate, anodic oxidation was used to pretreat the mirror-polished aluminum substrate, which effectively alleviated the rupture of the A1N film caused by the mismatch between A1N and A1, and improved the bonding strength between A1N film and Al substrate. The thickness of anodic alumina film of the composite substrate is 10 um.When the aluminum nitride film lum, the voltage resistance is more than 1350V, the insulation resistivity is 1.7x106AIN film and the bonding strength between the substrate and the substrate is more than 8Mpa.The substrate is not deformed and the aluminum nitride film is not broken under the thermal shock at 260 鈩，

本文编号：2114712