TO257TPackage Design And Preparation Of Metallization Layer On 95%Al₂O₃ Used For Electronic Packaging

Semiconductor devices catch more and more attention since the emergence of electronic manufacturing.With the continuous increase of the circuit density and improvement function,higher reliability packaging technology required for a better support of the electronic components.Electronic packaging materials upgrade from thermosetting plastics,silicone plastics and other organic materials to ceramics and metal materials.Packaging reliability directly determines the safety performance of electronic devices,especially in aviation and military industry.The improvement of the reliability of packaging is of great significance for the development of the semiconductor industry.This paper aims to improve the packeging technology of T0257T and sealing ability alumina ceramics use for electro-vacuum devices by preparing metallization layer.Explore the feasibility of chip protection improving by replacing the heat sink material,border and baseplate.Gass tightness and thermal resistant will be test to measure the package quality.At the same time,in order to improve the sealing ability between ceramic insulator and metal frame used in tube,the paper research the preparation of metallization layer on 95%Al₂O₃ ceramics.The metallization layer prepared by high temperature sintered method.On the basis of Mo-Mn method,the process of ceramic metallization is improved.This paper discusses the influence of MnO-SiO₂-Al₂O₃ and MnO-TiO₂ activator systems on the metallization layer and welding ablity and optimizes the metalized process of the two activation systems.The test results show that the reliability of chip protection can be improved without affecting the thermal resistance performance by replacing the material of the heatsink plate,the baseplate and the border.Each component assembled by silver-copper barzing at 800℃ last for 3min.All the conponents connected with average and smooth weld joint.Good package gained between Cu baseplate and 80WCu frame,which can afford 1000 times temperture follow and show high performance gas tight.Gas tightness detection shows that the leakage rate is less than the smallest display leakage rate,which means the tube reaches the aerospace level standard.Bidirection migration exists when metallization layer（with MnO-SiO₂-Al₂O₃ or MnO-TiO₂ as activator）stinterd on ceramic substrate.In the process of metal sintering,Mo particles happen to inadequacy densification at high temperatures.Oxides form high temperature liquid wet Mo particles and fill in the clearance of Mo particles.Liquid will react with the surface of Mo particles and form complex compounds such as 3CaO · MoO3 and 2MnO · 3MoO₂.These compounds form a good connection between Mo and the cooling liquid.The reaction between Mo particles and the oxide liquid improves the wettability beteen the liquid and Mo,which benefits the bonding strength of the metallized layer and the ceramic substrate.When preparing the metallization layer with MnO-TiO₂ as activator,both the interfacial chemical reaction and the migration of the liquid phase happened at the same time.MnO react with alumina ceramic substrate and form MnO·Al₂O₃.Good adhesion achieved at reaction zone between ceramics and metallization layer.The sintering temperature and activator content have great influence on the quality of metallization layer.In the specific temperature range,the density of metallization layer increases with the rise of sintering temperature.Meanwhile the porosity decreases and the mechanical properties of metallization layer improved.When using MnO-SiO₂-Al₂O₃ as activator with the proportion of 50:35:15,and three times Mo applied for preparation of metallization layer sintered at 1400℃,high compactness and better mechanical properties were gained.The bonding strength between the metallization layer and ceramics is high.After the tensile test,the failure can be found both in metalized layer and in ceramic substrate.When preparing the metallization layer with MnO-TiO₂ as activator,the MnO:TiO₂ were 63:37,MnO-TiO₂:Mo powder is 1:3,and sintered at 1450℃,the densification of the metallization layer is the best,the tensile rupture strength reaches the maximum.