Research And Control Of Organization Change And Oxidation Layer Of Copper During Direct Bonded Copper

The pre-oxidation process in direct bonded copper?DBC?technology has not been elaborated in the domestic and foreign.In this research project,the pre-oxidation process was explored in the context of fully reading the literature and understanding the principle,process conditions of DBC.In the process of researching the subject,means of testing and characterization were used such as measuring weight,metallographic camera,UV-Vis absorption spectroscopy,Raman spectrum and so on.Pre-oxidation conditions were controlled in order to get the information about the oxide film phase,thickness of oxide film and copper organizational change.The main work and achievements can be summarized as the following:?1?Cu₂O was formed on the surface of the copper foil when the oxidation temperature was between 400?and 800?,the oxidation time was 1h,the oxygen partial pressure was controlled at 100×10^-6700×10^-6.Under the condition of excessively high pre-oxidation temperature and oxygen partial pressure,copper foil surface would produce CuO phase.The oxide film thickens,loose surface and local oxide film off were not conducive to the preparation of DBC substrate.?2?With the increase of the oxidation temperature from 400?to 800?,grain recrystallization process occured and the grains grew up and the grain size increased.With the extension of holding time,the grains of different sizes and uneven distribution became into uniform size and grain growth speed was slower.Within a certain range,the effect of temperature on grain size was greater than the effect of holding time on grain size.?3?Gradient experiments showed that the bonding strength of samples which was prepared under 1070?,30min,nitrogen atmosphere reached 13.4MPa.Through the observation of the microstructure and phase analysis of the interlayer,it was found that the copper foil bonded closely with the alumina ceramic substrate with the optimum process parameters.The intermediate layer was CuAlO₂ and scattered in the alumina matrix.?4?When the grain size is 48.23?m,the bonding strength of the composite substrate has a maximum of 13.8MPa.?5?The composite substrate with high bonding strength?>12MPa?can be obtained,when the thickness of the oxide film was in the range of3.4?m⁶.7?m.Comprehensive comparison of various factors,the oxide film thickness to obtain the best adhesive strength was 5.2?m.?6?Based on the influence of copper grain size and oxide film thickness on the adhesion,it can be concluded that the optimum copper foil pre-oxidation process in direct bonded copper technology was 600?,1h,300×10^-6.