Preparation And Metalization Of The Alumina Ceramic Substrate For SMD

Alumina ceramic substrates with high mechanical strength,excellent insulation and thermal stability are widely used in surface mount device(SMD)packaging.This paper mainly reserched the process for preparation and metallization of alumina ceramic substrate used for SMD.The preparation and metallization of alumina ceramic substrate were reviewed in this paper at home and abroad.The dosage of main material,additives and the process parameters for tape casting were determined by studying the influence of materials,a variety of additives and the process parameters of tape casting on green tapes.Through the analysis of the viscosity and adhesion effect of metallized slurry,binder system was determined.The degreasing temperature-time curve and sintering temperature were ascertained by the thermal analysis of alumina substrate,tungsten film and tungsten powder and SEM images of the samples.In the process of tape casting,the Al2O3 powder with lower specific surface area could reduce the dosage of additives,such as binder.With the azeotropes of ethanol and methyl ethyl ketone as dispersion medium,the uniform and stable slurries for tape casting were preparaed with Al2O3 powders which specific surface area was 6.51 m2/g,lwt%dispersant,0.5wt%inhibitor and 6wt%binder of Al2O3,in addition,0.8 times plasticizer of the binder weight.The contents of slurry solid were between 73wt%and 75wt%,the viscosity between 1.0 and 1.5 Pa·s,the temperature of the slurry or the apparatus at 26±0.5?,and the height of hopper about 20±2mm.The binder for metalized slurry was the composite system of ethyl cellulose(EC 50)and polyvinyl butyral(PVB).The viscosity was 300Pa·s when binder concentration at 7%,and PVB/(EC 50+PVB)at 25%.Under these conditions,the metalized slurry was suitable for screen printing.The degreasing process before 600? was carried out in the wet hydrogen atmosphere,which temperature-time curve was as follows:the heating rate was 1-1.5?/min from 25 ? to 350?,the soaking time set for 15 min respectively in 215? and 35?,the heating rate 1.7?/min from 35? to 600?,and the soaking time set for 15 min at 600?.And the maximum sintering temperature and soaking time were at 1500? for 1.5 hr.Under these conditions,dense Al2O3 substrates,compact tungsten metalline layer,and between which firm interface,were prepared successfully.