Research On Manufacturing Technology Of Multilayer Ceramic Substrates

Ceramics have comprehensive characteristics of electrical,thermal,mechanical and dimensional stability,which are unsurpassed by any other materials.The multilayer substrates or shells for integrated circuit packaging are one of the most prominent applications for ceramics within the microelectronics sector.Currently,the mainstream manufacturing methods for multilayer ceramic substrates include HTCC technology and LTCC technology,both of which have reached a peak as product needs continuous updating and iteration.In recent years,multi-material 3D printing technology has gradually transferred from achieving entity structures with high shape accuracy to achieving entity structures with mechanical,electronic,optical,chemical and biological properties,and there have been many successful cases of multimaterial 3D printing of functional ceramic parts.In this paper,the following researches focus on highly reliable multilayer ceramic substrates and their advanced manufacturing processes have been carried out using a combination of theory,numerical simulations and experiments:(1)The histories,principles and application characteristics of HTCC/LTCC technologies as well as four major types of multi-material 3D printing techniques,namely Material Jetting,Direct Ink Writing,Fused Deposition Modeling and Vat Photopolymerization,are reviewed,and the latest advances in multi-material 3D printing of functional ceramic devices such as capacitors,substrates and microstrip antennas at home and abroad are investigated to establish the foundation for the relevant research in this field.(2)The general principles for the design of multilayer ceramic substrates are described.Special considerations,failure mechanisms,and test items are discussed in terms of manufacturability,heat dissipation,and reliability.The specific design flow of the multilayer ceramic substrate for a CMOS image sensor is provided,including type selection,structural design and electrical design.(3)The detailed study was carried out on the manufacturing process of high temperature co-fired ceramic technology,including drilling,filling,printing,stacking,lamination,thermal cutting,co-firing,Ni/Au electroplating,and separation.The finished multilayer ceramic substrates satisfy the use requirements.(4)With regard to drop-on-demand piezoelectric inkjet printing,the working mechanism of the piezoelectric printhead and the ink flow within the chamber are firstly analyzed based on piezoelectric actuation and wave propagation theory,and the ink droplet formation process and its dominant factors are elaborated.Secondly,a two-phase flow model of the orifice is established based on the level set method,and the effects of viscosity,surface tension,density,inlet velocity waveform and orifice diameter on the ink droplet formation process,including equivalent length,equivalent diameter,velocity,volume and satellite droplets,are investigated.Finally,a multisoftware integrated intelligent optimization system for inkjet printing was built and the automatic sampling,population information writing and calculation processes were demonstrated.(5)The inkjet printing scheme is proposed according to the structural characteristics of the multilayer ceramic substrate,and the influence of the wetting and spreading of ink droplets on the substrate or printing layer on the morphology of the dots and lines is theoretically analyzed.The feasibility of the inkjet printing scheme was demonstrated.