主題瀏覽
- 學位論文
矽基塗層厚度對功率型電阻元件阻值和表面溫度之影響
Effect of Coating Thickness of Silicon Resin on Resistance and Surface Temperature in Power Resistors
摘要
摘 要 矽基塗料於電阻的塗層保護為產業界的應用，一般應用其材料的絕緣性材與不燃性的考量。本研究中利用矽基塗料的熱傳導性質，在陶瓷基材的三氧化二鋁 含量為85﹪的圓柱型陶瓷棒，表面噴濺氧化錫為電導層，經加工程序後，試驗在電導層上塗佈矽基塗料，分別為無塗裝層、及塗層厚度為0.0435㎜、0.155㎜、0.3365㎜等四種厚度。研究中針對不同塗裝方式的樣品，在額定功率下，實際量測元件表面溫度，在塗層較厚元件的表面溫度較低。反之，溫度較高。相對的在塗層厚度較厚者，在相對的冷卻速度也比較慢。 以負荷1000小時實驗的電導層的阻值變化率，也印證使用較厚的矽基塗層時將可獲得比較低的表面溫度。當然，影響元件的溫度除本研究中所討論的塗層厚度外，也包括瓷棒中的三氧化二鋁含量、瓷棒尺寸等。其中影響最大的因素為瓷棒的三氧化二鋁含量(即電阻元件的系統熱阻值)。 本研究中在電導層噴濺的材料特性、噴濺溫度的維持、瓷棒中的三氧化二鋁含量 (85%)、瓷棒尺寸 (φ4.5㎜*14㎜) 等條件相同下，討論在不同的塗層厚度對元件表面溫度的影響。並藉以評估功率型電阻的壽命負荷，於定溫(70℃)中負荷時間為1000小時，依阻值變化率評估負荷壽命實驗的結果。從分析的結果發現： (一). 元件在額定功率下，塗層厚度小於0.3365mm時，表面溫度將隨著塗層厚度的增加而降低。 (二). 陶瓷基材的氧化金屬導電層不同的濺鍍溫度，在相同電壓負荷條件下，元件負荷後阻值變化率，在680℃與800℃的濺鍍溫度下，800℃的阻值變化率小於680℃阻值變化率。 (三). 由表面溫度的降低，元件負荷1000小時的阻值變化量隨著降低。
並列摘要
Abstract Silicon based polymeric coating is widely used for the protective coating of the resistors in the industry. Due to its properties of good insulation and non-flammability. This study is investigating the effect of the heat conduction properties of silicon based polymeric coating on the heat loading of the cylindrical shape ceramic rods system with different thickness of the coating on the surface. The ceramic rods contain 85% of Al2O3 and the surface is spray-coated with tin oxide (SnO2) as the conductive film. This conductive film will go through spiral grove type of cutting process to raise the resistance value of the conductive film to higher values. The surface of the processed filmed rods will be covered either with no silicon coating or different thickness (0.0435㎜、0.155㎜、0.3365㎜) of silicon coating. Under the same rated power applied to the ceramic rods system, the surface temperature of the rods is measured. When the coating is thicker, the surface temperature is lower and the cooling rate is also slower. Based on the percentage change of resistance value of the conductive film in the load same rated power 1000hr test, also indicates the lower surface temperature from a thicker coating. Besides the thickness of the coating that will affect the surface temperature of the system, the concentration of the Al2O3 and the dimension of the ceramic rods will also be important factors. Among them, the most critical one should be the content of Al2O3 which will dominate the heat resistance of the ceramic rod resistor system. In this study, the physical properties of the spray-coated SnO2 film and its process temperature as well the content of the Al2O3 (85%) and dimension of the ceramic rods (φ4.5㎜*14㎜) are fixed, the effect of different thickness of the silicon coating on the surface temperature of the system was studied. This was also been studied about the effect on the reliability property of the power type resistors under load life test (ambient temperature is 70℃and 1,000 hours of duration time). This is based on the percentage change of the resistance value from the load life test. From the analysis, the results can be summarized as follows: (1). Under the same loading power, and coating thickness is smaller than 0.3365mm, the surface temperature of the system is lower when the coating is getting thicker. (2). The different spray-coated temperature with metal oxide (SnO2) as the conductive film based ceramic composition, under the same voltage loading condition, and different pray-coated temperature on 680℃and 800℃, the percentage of change of the resistance value is smaller at 800℃than it at 680℃. (3). By lowering the surface temperature of the system, the percentage of change of the resistance value of the resistor components under load test for 1000 hour is reduced.