Research On Fabrication Of Metallic Pattern Based On Alumina Ceramics Surface And Its Application

Surface metallized ceramics with excellent electrical conductivity,thermal conductivity and stability characteristics,can be widely applied in electronic information,aerospace,automotive and other fields.At present,the commonly used methods of metallization on the ceramics are mainly of screen printing,magnetron sputtering,direct bonding copper,and electroless plating,which exists of some problems such as the process cumbersome,environment pollution and mass production difficulty.Based on this,the thesis proposed a method of fabrication of graphical metal conductive layer by means of inkjet printing and selective electroless plating on alumina ceramics.The method had the advantages of simple process,highly efficiency and environmental-friendly,which provides an effective way to expand the application of metalized-ceramics.The main research contents are as follows:Study on pretreatment of ceramic surface,through discussion of the effect of its surface with microstructure,contact angle,and roughness,the results showed that the adhesion strength of the conductive layer and the ceramic substrate was enhanced effectively.The physical and chemical properties of the catalytic functional ink were studied,which indicated that the ink had good storage stability and printing adaptability,and had good wetting and spreading characteristics on the ceramic surface.By adjusting the parameters of the inkjet printing technology,a pre-set pattern can be formed on the ceramic substrates,and the seed layer which can catalyze the growth of the subsequent metal copper layer can be obtained after curing at low temperature.On the ceramic substrates with catalytic seed layer,the growth of the copper layer was realized by selective electroless plating.The influence of different parameters on the morphology,square resistance,crystal structure and deposition rate of copper layer was studied.Eventually,the optimized technical parameters of copper layer growth were: 24 g/L C₄H₄O₆ KNa,3 g/L EDTA·2Na,8 g/L CuSO₄·5H2O,2 g/L NiSO₄·6H2O,15 mg/L K4Fe?CN?6,1.0 mg/L 2-MBT,14 mL/L HCHO,the pH is 13.0,the deposition temperature and time were 45 °C and 30 min,respectively.With an analysis and characterization of the prepared copper metal layer on alumina ceramics,the results shown that the copper layer was homogeneous and compact,only copper elements was observed in the copper layer and the copper layer had excellent crystallinity.The copper layer had excellent electrical conductivity and its resistivity as low as 2.42 ??·cm,which was only about 1.4 times higher than that of bulk copper.The resistance change rate of the metallic copper layer was measured at 0-125 °C and room temperature.The results showed that it had good environmental adaptability and storage reliability.The solderability and adhesion test results shown that the copper layer had excellent solderability and reliable adhesion,and the bonding strength of the substrate is 6.4 N/mm².In the as-prepared copper conductive patterns,the copper layers were thickened by electroplating.Under the current density of 2 A/dm² and the plated time of 30 min,the copper layers of thickness were achieved about of 14 ?m.The metal-patterned ceramic substrate was applied to high-power LED heat-dissipation substrate.The voltage-temperature coefficient of the LED was-0.87 mV/°C when the LED was operated by the forward voltage method.The junction temperature was about 67 °C and the thermal resistance was 17.5 K/W,indicating that the prepared metallized ceramic substrate can be used for high power LED ceramic package substrate.