Study On Two-sided Lapping Of SrTiO₃Ceramic Substrates And Its Surface Quality

SrTiO3ceramics, with high dielectric constant, low dielectric loss, high temperature stability, and dielectric strength, has been widely used in microelectronics. Now it has become an international hot topic in the study of electronic ceramic materials. However, pressureless sintering of strontium titanate ceramics substrate can’t be used effectively, because of its unflatness, poor uniformity and warpage surface. In ordre to meet the requirements of high surface flatness, small enough surface roughness and less surface and sub-surface damage, we have to process this material properly. In this paper, the flexible loading double-sided lapping process was used. The integrate surface can be obtained through this method. By optimizing the process parameters, the crushing rate was reduced and the lapping efficiency was improved. The main work of this research is as following:Firstly, a series of double-sided lapping experiments of strontium titanate ceramic were carried out to solve these problems. The effects of abrasive, lapping pressure, lapping speed, lapping fluid flow and other process parameters on the processing quality of SrTiO3ceramic substrates were studied systematacially. The relationship between material removal and surface roughness with processing parameters were obtained. By optimizing the process parameters, an efficient and stable process program of double side lapping was achieved.Secondly, the original and after processing morphology of SrTiO3ceramic substrates were studied by scanning electronic telescope (SEM), OLYMPUS4000, KEYENCE VHX-600. By observing the original morphology of SrTiO3ceramic substrates we found that grain size of strontium titanate was very uneven. There wre many irregular shape of porosity on the surface of SrTiO3as well. These pores in the subsequent lapping process cannot be completely removed. By measuring the porosity of strontium titanate ceramic substrate we found that strontium titanate substrate surface porosity was mainly produced in the process of sintering. This is a reflection of poor ceramic density. Thirdly, the effects of abrasive particle size uniformity and the size of the abrasive grain size on the processing quality of SrTiO3ceramic substrates were studied systematacially. Research shows that the size of abrasives plays an important role on the processing effects. The SrTiO3ceramic substrates which processed by uneven size of abrasives exist obvious scratches. Different sizes of abrasives have different ways of material removal. Using W7or bigger particle size of abrasive machining of strontium titanate substrate the Materials were mainly removed by brittle fracture. Using W2.5alumina abrasive machining both brittleness removal and plastic removal were existed.