Study On Low Temperature Co-Fired Composites Of Calcium Boroaluminosilicate Glass/Alumina

With the prosperity and rapid development of modern information technology,electronic devices are developing in the direction of high integration and transmission efficiency,which puts forward higher requirements for the performance of packaging substrates.Low temperature co-fired ceramic（LTCC）materials have superior performance,low sintering temperature,and easy mass production.All aspects performance of LTCC materials perfectly meet the needs of packaging substrate materials,and are gradually replacing traditional substrate materials.The domestic LTCC industry is still in its infancy,and the localization of materials is an important issue currently facing.In order to solve issue,meet the development needs of small size and modularity of electronic component,the development of high-strength LTCC materials has become a current research hotspot.This paper takes Ca O-B₂O₃-Al₂O₃-Si O₂（CBAS）glass/alumina composite system LTCC material as the research object,and studied the effects of Ca O and Ba O content in glass components,glass/ceramic ratio and sintering temperature on the sintering,structure and properties of the materials.The experiment prepared the material with the flexural strength of 210 MPa and the coefficient of thermal expansion of 6.00×10^-6 K^-1（30～500℃）,and the performance of LTCC material was improved.The main research results of this paper are as follows:（1）The increasing of Ca O content in the glass gradually decreased the degree of polymerization of the glass network,which can significantly reduce the viscosity of the glass and promote the densification of liquid phase sintering,and also improve the crystallization tendency of the materials,reduce the crystallization temperature,cause anorthite to be more easily precipitated.CBAS glass and alumina filler have good wettability,and the system sintering is reactive liquid phase sintering.Alumina can dissolve in the glass to promote the precipitation of anorthite.The precipitation of anorthite can reduce the sintering shrinkage and bulk density,an appropriate amount of anorthite can improve the flexural strength of the material by more than 190 MPa,and reduce the coefficient of thermal expansion of the material to in the range of 5.71～6.26×10^-6 K^-1（30～500℃）.（2）The equal mass fraction replacement of Ca O by Ba O in glass increased the degree of polymerization of the glass network,and Ba²⁺has weaker attraction to anionic groups than Ca²⁺,which resulted the viscosity of the glass first increases and then decreases.When the Ba O content in the glass exceeds 6.0 wt.%,in addition to anorthite,barium feldspar is also precipitated in the sample,and with the increase of sintering temperature,barium feldspar changes from hexagonal to monoclinic,which helps to reduce the coefficient of thermal expansion.The material properties were affected by the sintering densification and the precipitation crystal phase.The bulk density and flexural strength of material first increases,then decreases and finally increases.The coefficient of thermal expansion of B series samples is in the range of 5.44～6.10×10^-6 K^-1（30～500℃）.（3）The increase of the proportion of parent glass doesn’t change the crystallization temperature,but can improve the crystallization ability.Increasing the proportion of glass can cause the sintered densification of the material to increase first and then decrease.When the proportion of parent glass is low,the precipitation of anorthite can improve the flexural strength.The particle size of fused silica powder is smaller than that of parent glass powder,and adding fused silica powder helps to increase the heaped density of particles,thereby improving the sintering compactness.When the mass ratio of parent glass,fused silica powder and micron alumina balls is 40:5:55,the material obtained by sintering at 900℃has the best properties,the flexural strength is 210 MPa,and the thermal expansion coefficient is 6.00×10^-6 K^-1（30～500℃）,suitable for LTCC substrate package.