| As the rapid development of advanced material, new process and neoteric technique, microelectronic material got a booming market in the last 20 years. Technique of Low Temperature Co-fired Ceramic will become the top choice of modularization and a new economic growth point, because of its excellent character in electricity, machinery, thermology and craft. The domestic development and industrialization of LTCC lags behind that in developed countries, expecially in integrating module. We are unable to break loose from the high price and control of the foreign offerings for the scarce assortment and bad quality. In this thesis, taking the silver paste of LTCC bluetooth antenna inner electrode as the research objective, we researched the preparation method of high dispersing silver powder by chemical deposition, designed the ingredient and preparation process of glass frits, prepared organic vehicles though adding modifier, and optimized the constitutions of the goal silver paste. With the help of scanning electron microscope, laser scattering particle analyzer, PF-100B vibration solid density spectrometer, Netzsch DTA 449PC DSCmeter and D/Max 2500XRD,we observed and analysed the morphologies, mean grain sizes, tap density of silver powder, and the themal features of glass frits. By Viscometer and Fineness dispersion meter, the viscocity and fineness had been measured. Through SEM, we surveyed the morphology of sintered film. Four point probe meter and forcemeter measured the electroconductibility and adhesion of the sintered film. The results are as follows:(1) Selecting ascorbic acid as reducing agent and gelatine as dispersing agent,we got the fine dispersing silver powder though chemical reduction method. When C(AgNO3):C(Vc)=2:1 and m(gelatin):m(AgNO3)=2:100,the mean grain sizes of fine dispersing silver powder is 2.68μm. When acidity of solution is 2, the drop rate is 200mL/min and temperature is 50℃, we can got crystalline silver powder of which the mean grain sizes is 2.46μm.(2) The viscocity of LTCC paste optimised for inner electron is 120 Pa-s. The paste prepared by silver powder of 2.46μm could get fine screen printing and the resistance of its sinterd film could reach 1.40 mΩ/□. The higher the tap density of silver powder is, the finer the conductivity of sinterd film is. When the tap density of silver powder is 5.1 mΩ/□, the conductivity of its sinterd film was 1.02mΩ/□. When m(Ag):m(glass frits)=82:3, the sintered film obtains the best electronic property,1.22 mΩ/□. From the TG graph of organic vehical,1# vehical is much suitable to the LTCC sinter process and the residul is only 0.03%. When the content of vehical is 15wt%, the resistance of the sinterd film was 1.45 mΩ/□.(3) The soften temperature of glass C which is not devitrification optimized from six kinds glass frits is about 650℃. The TEC of glass C calculated by Turner model can match that of the green tape. In addition, when the content of Li2O is 2wt% in glass, the coordination is fine between sinterd film and substrate with good electroconductivity. The adhesive of the sintered film can reach 16.8N/mm with 8wt% of glass frits in the paste.(4) If the ceramic green tape is added into the silver paste as the addition,it can restrain the mismatch shrinkage and warpage due to the different materials in X and Y directions. With the increase of the green tape addtion content, the efficiency of the bluetooth antenna is first increased and then rapid decreased. When the content of addtion is 0.6wt%, it can approach to the designed velue,2.44GHz. Lecithin and castor oil as the surfactant of paste can improve the levelling property. For enhancing the aspect ratio of sintered film, dibutyl phthalate in the paste can increase the thixotropism. When the content of dibutyl phthalate is 12wt%, the aspect ratio of sintered film can reach 0.32. |
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